Patent Application
20220026447
The present disclosure relates to a marker for diagnosing a neurodegenerative disease and a use thereof, and more particularly, to a marker composition for diagnosing a neurodegenerative disease, which includes a glutathionylated FUS protein, a composition for diagnosing a neurodegenerative disease, which includes a preparation of measuring a glutathionylation level of a FUS protein, a kit for diagnosing a neurodegenerative disease, which includes the composition, and a method of providing information on diagnosis of a neurodegenerative disease using the same.
In addition, the present disclosure relates to a composition for treating a neurodegenerative disease, which includes GstO2, and more particularly, to a composition for preventing or treating a neurodegenerative disease, which includes GstO2 inducing deglutathionylation of a FUS protein.
Amyotrophic lateral sclerosis (ALS) is a fatal adult-onset neurodegenerative disease which is characterized by the gradual degeneration of motoneurons. ALS causes progressive muscle weakness, leading to fatal muscle atrophy and paralysis, and death within 3 to 5 years after the onset of the disease. ALS may be classified into sporadic ALS whose cause is not known, and familial ALS due to genetic defects in proteins directly related to pathology, such as superoxide dismutase1 (SOD1), transactive response DNA-binding protein-43 (TDP-43), fused in sarcoma (FUS) or TATA-binding protein-associated factor15 (TAF15). It was revealed that mutant-type TDP-43 has toxicity in neurons, and mislocalization of the protein is associated with the onset of ALS.
In addition, protein aggregates are characteristically found in age-related neurodegenerative diseases (NDs) for example, Parkinson's disease (PD), Alzheimer's disease (AD), Huntington's disease (HD) and amyotrophic lateral sclerosis (ALS, also called Lou Gehrig's disease).
Fused-in-Sarcoma (FUS) is a RNA and DNA-binding protein, and it is known that the N-terminus of the FUS protein is associated with transcriptional activity, and the C-terminus thereof is associated with protein and RNA binding. The FUS protein includes recognition sites for AP2, GCF and Sp1, which are transcription factors, and in a recent study, various types of mutant FUS proteins have been identified in patients with ALS or frontotemporal dementia. It was revealed that the mutant FUS protein escaped from its original position in the nucleus and then was located in a stress granule, thereby forming an aggregate.
Meanwhile, FUS mutations were shown in most ALS patients (Mackenzie et al., 2010), a FUSP525L mutation indicates mislocalization in the cytoplasm and is associated with acute FUS-induced ALS (Sun et al., 2011), and wild-type FUS and its variant, FUSP525L, are known to exhibit the same phenotype, such as rough eyes, and reduced locomotive activity in Drosophila (Chen et al., 2016; Jackel et al., 2015).
Although ALS cannot be diagnosed with magnetic resonance imaging (MRI) or a blood test, it can be diagnosed through a physical examination based on a patient's symptoms and a physical examination by experienced medical personnel. Studies on a method for diagnosing ALS by measuring the expression level of MARCH5 and MFN2 genes or protein activity have been attempted (Korean Patent No. 10-1674920), and there is still a lack of research on a marker or composition for ALS diagnosis related to a FUS protein and an aggregate of the FUS protein.
In addition, little is known about the mechanisms involved in the abnormal location of FUS mutant proteins and aggregate accumulation, which are found in ALS patients or frontotemporal dementia patients, and there are no therapeutic methods based thereon. As described above, various studies have been attempted to develop therapeutic drugs by confirming the formation of FUS aggregates and their action mechanisms (Korean Patent No. 10-1576602), but are still insufficient.
Therefore, the inventors found that a FUS protein that should usually be located in the nucleus is located in the form of a glutathionylated FUS protein aggregate in the cytoplasm while searching for a novel marker for diagnosing a neurodegenerative disease, and confirmed that the glutathionylated FUS protein can be a novel marker that is able to diagnose a neurodegenerative disease, and thus the present disclosure was completed.
In addition, the present disclosure is devised to solve the above-described problem, and as a result of various studies, it was confirmed that the formation of a protein aggregate by the glutathionylation of a FUS protein known as an ALS-induced protein and its deposition in the cytoplasm of brain neurons cause ALS, and the glutathionylation inhibitory activity of a FUS protein of omega class glutathione transferase (GSTO) was confirmed. Based on this, the present disclosure was completed.
The present disclosure is directed to providing a marker composition for diagnosing a neurodegenerative disease, which includes a glutathionylated FUS protein.
The present disclosure is also directed to providing a composition for diagnosing a neurodegenerative disease, which includes a preparation for measuring the glutathionylation level of a FUS protein and a kit for diagnosing a neurodegenerative disease, which includes the composition.
The present disclosure is also directed to providing a method of providing information for diagnosing a neurodegenerative disease, which includes measuring the glutathionylation level of a FUS protein in a subject-derived biological sample and comparing the glutathionylation level with that of a normal person.
The present disclosure is also directed to providing a pharmaceutical composition for preventing or treating a neurodegenerative disease, which includes GSTO1 or omega class glutathione transferase 2 (GstO2) gene or a protein encoding the gene as an active ingredient.
However, technical problems to be solved in the present disclosure are not limited to the above-described problems, and other problems which are not described herein will be fully understood by those of ordinary skill in the art from the following descriptions.
To attain the above-described objects, the present disclosure provides a marker composition for diagnosing a neurodegenerative disease, which includes a glutathionylated FUS protein.
In one embodiment of the present disclosure, the neurodegenerative disease may be amyotrophic lateral sclerosis (ALS).
In another embodiment of the present disclosure, the FUS protein may be glutathionylated at a Cys-447 residue.
In addition, the present disclosure provides a composition for diagnosing a neurodegenerative disease, which includes a preparation for measuring the glutathionylation level of a FUS protein.
In one embodiment of the present disclosure, the FUS protein may consist of the amino acid sequence represented by SEQ ID NO: 1.
In one embodiment of the present disclosure, the neurodegenerative disease may be ALS.
In addition, the present disclosure provides a kit for diagnosing a neurodegenerative disease, which includes the composition.
In addition, the present disclosure provides a method for providing information on diagnosis of a neurodegenerative disease, which includes: a) measuring a glutathionylation level of a FUS protein from a subject-derived biological sample and b) comparing the glutathionylation level of the FUS protein with a glutathionylation level of a FUS protein of a normal control sample.
In addition, the present disclosure provides a pharmaceutical composition for preventing or treating a neurodegenerative disease, which includes a GSTO1 or GstO2 gene or a protein encoding the same as an active ingredient.
In one embodiment of the present disclosure, the GSTO1 gene may consist of the base sequence represented by SEQ ID NO: 2.
In another embodiment of the present disclosure, the GSTO1 protein may consist of the amino acid sequence represented by SEQ ID NO: 3.
In still another embodiment of the present disclosure, the GstO2 gene may consist of the base sequence represented by SEQ ID NO: 4.
In yet another embodiment of the present disclosure, the GstO2 protein may consist of the amino acid sequence represented by SEQ ID NO: 5.
In yet another embodiment of the present disclosure, the neurodegenerative disease may be ALS.
In yet another embodiment of the present disclosure, the composition may inhibit the glutathionylation of a FUS protein.
In yet another embodiment of the present disclosure, the glutathionylation of the FUS protein may be glutathionylation at the Cys-447 residue of FUS.
In addition, the present disclosure provides a method of preventing or treating a neurodegenerative disease, which includes administering the composition to a subject.
In addition, the present disclosure provides a use of the composition for preventing or treating a neurodegenerative disease.
The inventors identified that a glutathionylated FUS protein serves as a marker for diagnosing a neurodegenerative disease, and thus a composition for diagnosing a neurodegenerative disease according to the present disclosure will contribute to early diagnosis of a neurodegenerative disease.
In addition, the inventors identified that the glutathionylation of FUS known as an ALS-inducing protein is the ALS pathogenesis mechanism that increases aggregation in the cytoplasm and neurotoxicity, and confirmed that a composition for preventing or treating a neurodegenerative disease according to the present disclosure includes GSTO1 or GstO2, which induces the deglutathionylation of a FUS protein, has an effect of inhibiting brain cytoplasm aggregation and neurocytotoxicity. Therefore, it is expected to be effectively used in preventing, treating or alleviating a neurodegenerative disease.
Hereinafter, the present disclosure will be described in detail.
As a result of various studies on neurodegenerative diseases, the inventors found that the glutathionylation of a FUS protein, which is known as one of the causes of ALS, results in formation of a FUS protein aggregate, and identified that the FUS protein aggregate serves as a marker for diagnosing ALS, and thus the invention was completed.
Therefore, the present disclosure provides a marker composition for diagnosing a neurodegenerative disease, which includes a glutathionylated FUS protein, a composition for diagnosing a neurodegenerative disease, which includes a preparation of measuring a glutathionylation level of a FUS protein, and a kit for diagnosing a neurodegenerative disease, which includes the composition.
The gene encoding a FUS protein according to the present disclosure may consist of the base sequence represented by SEQ ID NO: 1, or the amino acid sequence represented by SEQ ID NO: 2. Here, the gene encoding a FUS protein may include a base sequence having 70% or more, preferably 80% or more, more preferably 90% or more, and most preferably 95% or more sequence homology with the base sequence represented by SEQ ID NO: 1.
The target disease of the present disclosure, “neurodegenerative disease” refers to the generic term for diseases leading to the death of neurons in one or various part(s) of the nervous system. Types of neuron death include necrosis or apoptosis. The target disease includes preferably Alzheimer's disease, mild cognitive impairment, stroke, vascular dementia, frontotemporal dementia, Lewy body dementia, Creutzfeldt-Jacob disease, traumatic head injuries, syphilis, acquired immunodeficiency syndrome, other viral infections, brain abscesses, brain tumors, multiple sclerosis, Parkinson's disease, Huntington's disease, Pick's disease, ALS, epilepsy, and ischemia, and more preferably ALS, but the present disclosure is not limited thereto.
The “fused in sarcoma (FUS) protein” known as one of the causes of a neurodegenerative disease in the present disclosure is a RNA and DNA-binding protein, and here, it is known that the N-terminus of FUS is associated with transcriptional activity, and the C-terminus thereof is associated with protein and RNA binding.
The term “glutathionylation” used herein refers to the formation of a disulfide bond between a cysteine and a reduced glutathione (GSH). The glutathionylation of a protein induces changes in the structure and function of a protein.
As it was described that the formation of a FUS protein aggregate caused by the glutathionylation of a FUS protein known as an ALS-inducing protein and the deposition of the aggregate in the cytoplasm are the causes of ALS, in one embodiment of the present disclosure, by a western blotting analysis using an anti-GSH antibody and an anti-myc antibody, it was confirmed that the glutathionylation of a FUS protein occurs depending on the concentration of an oxidized glutathione (glutathione disulfide; GSSH) in vitro (see Example 2), and a glutathionylated FUS protein aggregate was confirmed in the cytoplasm of a neuron by performing an experiment for confirming whether the glutathionylation of a FUS protein occurs in vivo (see Example 3).
In another embodiment of the present disclosure, an experiment for expressing a human FUS protein and a mutant FUSP525L protein in Neuron2a (N2a) was performed, confirming that the glutathionylation of a human wild-type FUS protein and a mutant FUSP525L protein occurs in mammalian systems in the same manner as described above (see Example 4).
In still another embodiment of the present disclosure, MALDI-mass spectroscopy and sequencing of the RanBP2 zinc-finger domain were performed to confirm that GSSH-induced glutathionylation occurs at Cys-447 of the RanBP2 zinc-finger domain in a FUS protein (see Example 5).
In yet another embodiment of the present disclosure, the analysis of the solubility of a glutathionylated FUS protein and the analysis of the three-dimensional homology model of the RanBP2 zinc-finger domain of a FUS protein were performed to confirm that the glutathionylation of the FUS protein induces the formation of the protein aggregate (see Example 6).
The above results show that glutathionylation occurs at Cys-447 of the RanBP2 zinc-finger domain in the FUS protein, and a glutathionylated FUS protein aggregate is formed, and the aggregate is deposited in the cytoplasm due to low solubility, shown in
The term “diagnosis” used herein refers to, in a broad sense, judgment of the condition of a patient's disease in all aspects. The contents of the judgment include the name of a disease, etiology, a disease type, severity, the details of pathology and the presence of complications. The diagnosis in the present disclosure is determination of the occurrence and stage of progression of a neurodegenerative disease.
Another aspect of the present disclosure provides a method of providing information on diagnosis of a neurodegenerative disease, which includes measuring a glutathionylation level of a FUS protein from a subject-derived biological sample and comparing the glutathionylation level of the FUS protein with a glutathionylation level of a FUS protein in a normal control sample.
The term “method of providing information on diagnosis of a neurodegenerative disease” used herein refers to providing objective basic information required for diagnosis of a neurodegenerative disease as a preliminary step for diagnosis or predicting prognosis, but excluding a doctor's clinical judgment or opinion. The subject-derived biological sample may be, for example, tissue or a cell, but the present disclosure is not limited thereto.
In addition, as a result of various studies on treatment of a neurodegenerative disease, it was confirmed that the formation of a protein aggregate due to the glutathionylation of a FUS protein known as an ALS-inducing protein and the deposition thereof in the cytoplasm of brain neurons cause ALS, and the activity of omega class glutathione transferase (GSTO) for inhibiting the glutathionylation of a FUS protein was confirmed. Therefore, the present disclosure was completed.
Therefore, the present disclosure provides a pharmaceutical composition for preventing or treating a neurodegenerative disease, which includes GSTO1 or omega class glutathione transferase 2 (GstO2) gene or a protein encoding the gene as an active ingredient.
The GSTO1 gene according to the present disclosure may consist of the base sequence represented by SEQ ID NO: 2 (Human GSTO1 NCBI Accession: NM_004832.2), or the amino acid sequence represented by SEQ ID NO: 3 (Human GSTO1 NCBI Accession: NP_004823.1). Here, the GSTO1 gene may include a base sequence having 70% or more, preferably 80% or more, more preferably 90% or more, and most preferably 95% or more sequence homology with the base sequence represented by SEQ ID NO: 2.
In addition, the GstO2 gene according to the present disclosure may consist of the base sequence represented by SEQ ID NO: 4 (Drosophila GstO2 NCBI Accession: NM_168277.2), or the amino acid sequence represented by SEQ ID NO: 5 (Drosophila GstO2 NCBI Accession: NP_729388.1). Here, the GstO2 gene may include a base sequence having 70% or more, preferably 80% or more, more preferably 90% or more, and most preferably 95% or more sequence homology with the base sequence represented by SEQ ID NO: 4.
The term “glutathionylation” used herein is the result of a disulfide bond between a cysteine and a reduced glutathione (GSH), which is known to bring about changes in the structure and function of a protein.
As described above in the present disclosure, it was confirmed that the formation of a protein aggregate by the glutathionylation of a FUS protein known as an ALS-inducing protein and the deposition thereof in the cytoplasm of brain neurons cause ALS. Therefore, in one embodiment of the present disclosure, as a result of culturing FUS in the presence of GSSG, it was confirmed that, as the GSH content increases, not only does the content of glutathionylated FUS increase, but also FUS is glutathionylated at Cys-447 (see Example 7), and due to the FUS glutathionylation, the formation of a FUS aggregate was specifically confirmed (see Example 8).
In another embodiment of the present disclosure, as a protein capable of regulating pathology due to glutathionylated FUS, GstO was identified, and it was confirmed that GstO2 has an effect of alleviating phenotypic defects and mitochondrial division and a functional disorder due to FUS overexpression in Drosophila (see Examples 9 and 10).
In still another embodiment of the present disclosure, not only the GstO2-induced effect of inhibiting the formation of a FUS aggregate in Drosophila neurons was confirmed, but also GstO2-induced regulation of FUS glutathionylation in Drosophila neurons was specifically confirmed (see Examples 11 and 12). In addition, it was confirmed that flies exhibiting an ALS phenotype due to the expression of FUS mutant FUSP525L also show the same effects as the GstO2-overexpressing FUS (see Example 13). Finally, the inventors confirmed the neurocytotoxicity inhibitory effect of GSTO1, which is a human homologous chromosome of GstO2 in order to confirm whether the recovery effect of GstO2 on FUS-induced neurocytotoxicity is also applied to a mammalian system, demonstrating that the effect of improving FUS insolubility and FUS-induced apoptosis is also specifically confirmed in a mammalian neuron model with ALS (see Example 14).
From these results, it can be inferred that GSTO1 or GstO2 induces FUS deglutathionylation, and exhibits an inhibitory effect on cytoplasmic FUS aggregation and neurotoxicity, indicating that GSTO1 or GstO2 can be effectively used as a therapeutic agent for a neurodegenerative disease.
The pharmaceutical composition according to the present disclosure may include a GSTO1 or GstO2 gene or a protein encoding the gene as an active ingredient, and may also include a pharmaceutically acceptable carrier. The pharmaceutically acceptable carrier is generally used in formulation, and includes saline, distilled water, Ringer's solution, buffered saline, cyclodextrin, a dextrose solution, a maltodextrin solution, glycerol, ethanol, liposomes, etc., but the present disclosure is not limited thereto. If needed, the pharmaceutically composition may further include other conventional additives including an antioxidant, a buffer, etc. In addition, by additionally adding a diluent, a dispersant, a surfactant, a binder or a lubricant, the pharmaceutical composition may be formulated as an injectable form such as an aqueous solution, an emulsion or a suspension, a pill, a capsule, a granule or a tablet. Suitable pharmaceutically acceptable carriers and their formulations may be formulated according to each ingredient using a method disclosed in the Remington's Pharmaceutical Science. The pharmaceutical composition of the present disclosure is not limited in dosage form, and thus may be formulated as an injection, an inhalant, a dermal preparation for external use, or an oral preparation.
The pharmaceutical composition of the present disclosure may be administered orally or non-orally (e.g., intravenously, subcutaneously, percutaneously, nasally or intratracheally) according to a desired method, and a dose of the pharmaceutical composition of the present disclosure may be selected according to a patient's condition and body weight, severity of a disease, a dosage form, an administration route and duration by those of ordinary skill in the art.
The pharmaceutical composition of the present disclosure is administered at a pharmaceutically effective amount. The “pharmaceutically effective amount” used herein refers to an amount sufficient for treating a disease at a reasonable benefit/risk ratio applicable for medical treatment, and an effective dosage may be determined by parameters including a type of a patient's disease, severity, drug activity, sensitivity to a drug, administration time, an administration route and an excretion rate, the duration of treatment and drugs simultaneously used, and other parameters well known in the medical field. The pharmaceutical composition of the present disclosure may be administered separately or in combination with other therapeutic agents, and may be sequentially or simultaneously administered with a conventional therapeutic agent, or administered in a single or multiple dose(s). In consideration of all of the above-mentioned parameters, it is important to achieve the maximum effect with the minimum dose without a side effect, and such a dose may be easily determined by one of ordinary skill in the art.
Specifically, the effective amount of the composition according to the present disclosure may vary according to a patient's age, sex or body weight, and generally, 0.001 to 150 mg, and preferably 0.01 to 100 mg per kg of body weight may be administered daily or every other day, or one to three times a day. However, the effective amount may be increased or decreased depending on the route of administration, the severity of obesity, sex, a body weight or age, and thus it does not limit the scope of the present disclosure in any way.
Meanwhile, as another aspect of the present disclosure, the present disclosure provides a method of preventing, regulating or treating a neurodegenerative disease, which includes administering the pharmaceutical composition to a subject.
The term “prevention” used herein refers to all actions that inhibit a neurodegenerative disease or delay the onset thereof by administration of the pharmaceutical composition according to the present disclosure.
The term “treatment” used herein refers to all actions involved in alleviating or beneficially changing symptoms of neurodegenerative disease by administration of the pharmaceutical composition according to the present disclosure.
The term “subject” used herein refers to a target in need of a prevention, regulation or treatment of a disease, and more specifically, a mammal such as a human or a non-human primate, a mouse, a rat, a dog, a cat, a horse, or a cow.
Hereinafter, to help in understanding the present disclosure, exemplary examples will be suggested. However, the following examples are merely provided to more easily understand the present disclosure, and not to limit the present disclosure.
1-1. Preparation of Drosophila melanogaster
All Drosophila stocks were stored under a standard food condition, a normal temperature (25° C.) and a normal humidity condition (60%), and Drosophila crossing was carried out according to standard procedures, and all offspring were raised at 25° C.
1-2. Cell Culture
Mouse neuroblastoma, Neuro2a cells, were cultured in DMEM (Life Technologies) containing 10% fetal bovine serum (FBS; Gibco) and a penicillin-streptomycin solution (50 mg/mL; Gibco) at 37° C. and 5% CO2/95% air conditions.
1-3. In Vitro Glutathionylation Assay
The full-length protein of myc-tag human FUS (0.51 μg) purified from HEK293 (OriGene) cells was incubated in 50 mM Tris-HCl (pH 7.5) in the presence of various concentrations of an oxidized glutathione (glutathione disulfide, GSSG) at 25° C., and one hour after incubation, the sample was placed on ice, and 3× non-reducing LDS sample buffer (Invitrogen) was added. Afterward, the sample was isolated by 12% SDS-PAGE and subjected to western blotting analysis using mouse anti-GSH (1:1,000; ViroGen Corp.) and mouse anti-myc (1:1,000; Millipore) antibodies.
1-4. Transformed Flies
UAS-FUS and UAS-FUSP525L cell lines were obtained from Nancy M. Bonini (University of Pennsylvania), and a UAS-GstO2 cell line was obtained according to a previous document (Kim et al., 2012; Kim and Yim, 2013). In addition, UAS-GSTO1 RNAi (BL34727, v26711), UAS-GstO2 RNAi (v109255), and UAS-GstO3 RNAi (v105274) cell lines were obtained from the Bloomington Drosophila Stock Center and the Vienna Drosophila RNAi Center, a UAS-mitoGFP cell line was obtained from H. J. Bellen (Baylor College of Medicine), and a pan-neuronal driver, elav-Gal4, muscle-specific driver, mhc-Gal4, motoneuron-specific driver and D42-Gal4 cell lines were also obtained from the Bloomington Drosophila Stock Center and the Vienna Drosophila RNAi Center. Here, W1118 flies were used as a control according to a genetic background.
1-5. Transfection
N2a cells were plated in a 6-well plate, and transfected with 4 μg of pCMV6-FUS-green fluorescent protein (GFP)-labeled human wild-type FUS or pCMV6-FUSP525L-GFP-labeled mutant FUSP525L using a Lipofectamine 3000 reagent (Invitrogen) according to the manufacturer's manual. Here, an empty pCMV6-AC-GFP plasmid was used as a negative control.
1-6. Generation of Stable Cell Line
N2a cells in a 24-well plate were transfected with 1 μg of human GSTO1 cDNA using a Lipofectamine 3000 reagent (Invitrogen), and for 2 days after transfection, stable transformants were selected in the presence of G418 (600 μg/mL). Here, the overexpression of a GSTO1 protein in the stable transformant was confirmed through an immunoblotting assay.
1-7. Total Brain Immunostaining
The adult brain of a 7-day-old adult male fly was fixed with 4% formaldehyde in a fixation buffer (100 mM PIPES, 1 mM EGTA, 1% Triton X-100, 2 mM MgSO4, pH 6.9), blocked with a washing buffer (50 mM Tris-HCl, 150 mM NaCl, 0.1% Triton X-100 and 0.5 mg/mL BSA, pH 6.8) containing 10 mg/mL BSA, and then incubated with primary antibodies diluted with a blocking buffer at 4° C. for 12 hours, and here, the used antibodies are as follows:
Rabbit anti-FUS (1:100, Bethyl Laboratories), mouse anti-FUS (1:50, Santa Cruz Biotechnology), rabbit anti-GstO2 (1:20), and mouse anti-GSH.
Afterward, the sample was incubated with an Alexa 488-conjugated secondary antibody (1:200, Invitrogen), a Cy3-conjugated secondary antibody (1:200, Jackson Immuno Research Laboratories) and DAPI (1:500, Sigma-Aldrich), and the brain was washed three times for 10 minutes with a washing buffer, and fixed with a SlowFade™ Gold antifade reagent (Invitrogen). Here, all images were obtained using a Carl Zeiss confocal microscope LSM710).
1-8. Immunohistochemistry
Cells were fixed with 4% paraformaldehyde in phosphate-buffered saline (PBS) for 30 minutes, and washed three times for 10 minutes with PBS containing 0.3% Triton X-100 (PBST). Afterward, the cells were incubated for 1 hour at 25° C. with a blocking buffer (PBST containing 5% normal goat serum (NGS)) and primary antibodies diluted with a blocking buffer at 4° C. for 12 hours. Here, the used antibodies are as follows:
Mouse anti-GSH (1:100; ViroGen Corp.), rabbit anti-FUS (1:100; Bethyl Laboratories), mouse anti-GFP (1:200; Roche) and rabbit anti-cleaved caspase-3 (1:500, Cell Signaling).
After incubation with primary antibodies, the cells were washed three times for 10 minutes with PBST, and incubated with secondary antibodies diluted in PBST at 1:2000 at 25° C. for 1 hour. Here, the used secondary antibodies are as follows:
Alexa-594-conjugated goat anti-rabbit IgG, Alexa-488-conjugated goat anti-rabbit IgG, Alexa 594-conjugated goat anti-mouse IgM and Alexa-488-conjugated goat anti-mouse IgG (Jackson Immuno Research Laboratories).
Afterward, the samples were observed using a Leica confocal microscope.
Afterward, for analysis of a neuromuscular junction (NMJ) in Drosophila, 3rd instar larvae were dissected, and fixed with 4% formaldehyde in PBS for 15 minutes. Subsequently, the samples were washed with 0.1% Triton X-100-containing PBS three times for 10 minutes, blocked with 5% BSA in PBST, and incubated with primary antibodies at 4° C. for 12 hours. Here, FITC-conjugated anti-HRP (Jackson Immuno Research Laboratories) was used at 1:150, and fixed by treating SlowFade™ Gold antifade reagent (Invitrogen), and all images were obtained using a Leica TCS SP5 AOBS confocal microscope.
1-9. Homology Modeling
The 3D structure of the FUS ZnF domain (32 amino acid residues, 422-RAGDWKCPNPTCENMNFSWRNECNQCKAPKPD-453) was predicted and created in order to predict the structure and function of a protein using I-TASSER server based on Molegro Molecular Viewer 2.5.0 (Molegro ApS, Aarhus C, Denmark).
1-10. In Vitro Protein Aggregation Assay
After in vitro glutathionylation, a sample was subjected to heat-block at 37° C., centrifuged at 4° C. for 30 minutes under a condition of 20,000×g, thereby being divided into supernatant and pellet fractions. The pellet was washed with 50 mM Tris-HCl (pH 7.5) five times for 10 minutes, and lysed with a reducing agent in an LDS sample buffer (2% SDS; Invitrogen). In both fractions, FUS was detected with rabbit anti-FUS (1:1000; Bethyl Laboratories) antibodies by western blotting analysis.
1-11. External Eye Microscopy
An eye image of adult Drosophila was taken with a digital camera by fixing the head on a slide glass. Here, 5-day-old male Drosophilae were used for an experiment. Meanwhile, the image was taken using a Leica MZ10 F stereomicroscope and a Leica DFC450 camera system.
1-12. Locomotive Activity and Lifespan Assays
For larval crawling assay, to remove food waste remaining on 3rd instar larvae, the larvae were washed with PBS, dried on a clean filter, and placed on a 2% grape juice-agar petri dish to allow the larvae to crawl for 90 seconds. Here, to quantify larval crawling behavior, the larvae were tracked and distance was measured using Image J software, and the results for at least 10 larvae were averaged for each transgenic line.
Afterward, for a climbing assay, ten male Drosophilae in each age group were anesthetized with carbon dioxide, put into column vials, and then transferred to empty vials to be incubated at room temperature for 1 hour and acclimated to the environment, and the number of Drosophilae climbing up to the top of the vial within 10 seconds was counted. Here, the experiment was independently repeated four times for each transgenic line every five minutes, and all of the climbing experiments were performed at 25° C.
Finally, for a lifespan assay, twenty male Drosophilae of each genotype (>150 Drosophilae) were put into respective vials and maintained at 25° C., and then all groups were transferred into new vials, followed by counting the number of dead Drosophilae.
1-13. Immunoblot Analysis
A protein extract for western blotting analysis was prepared by homogenizing heads of ten 14-day-old male Drosophilae in an LDS sample buffer (Invitrogen), and the total protein extract was isolated using a 4% to 12% gradient SDS-PAGE gel and transferred to a PVDF membrane (Millipore), and the membrane was blocked with Tris-buffered saline containing 4% skim milk or 4% bovine serum albumin (BSA) for 1 hour, and incubated with primary antibodies at 4° C. for 12 hours.
Here, the primary antibodies used herein are as follows:
Rabbit anti-FUS (1:1000, Bethyl Laboratories), rabbit anti-Drosophila Marf (1:1000, Leo Pallanck, a gift from the University of Washington, Seattle, Wash.), mouse anti-Opa1 (1:1000; mouse anti-UQCRC2 (1:1000, Abcam), mouse anti-ATP5A (1:10000, Abcam), mouse anti-Drosophila GstO2 (1:1000), rabbit anti-lamin C (Developmental Studies Hybrodoma Bank, DSHB), rabbit anti-α-tubulin (1:2000, Sigma), and rabbit anti β-actin (1:4000, Cell Signaling).
Blots were washed in TBS containing 0.1% Tween-20 (TBST) and incubated with secondary antibodies, and primary antibodies were detected with HRP-conjugated secondary antibodies using a goat anti-rabbit IgG HRP conjugate and a goat anti-mouse IgG HRP conjugate (1:2000, Millipore). Here, detection was carried out suing an ECL-Plus kit (Amersham).
Subsequently, the protein extract was homogenized in an RIPA buffer (Cell Signaling) containing a protease-phosphatase inhibitor cocktail (Roche), and mixed with a LDS sample buffer (Invitrogen) in combination with a reducing agent. Afterward, a protein sample was separated with a 4% to 12% Bis-Tris gel (Novex), transferred to a PVDF membrane (Novex), and subjected to western blotting analysis using rabbit anti-TurboGFP (1:2000, OriGene), mouse anti-GSTO1 (1:1000, Proteintech), rabbit anti-DDK (1:1000, OriGene) and rabbit anti-α-tubulin (1:2000, Sigma) primary antibodies.
1-14. Image and Morphology of Mitochondria
To confirm the image of mitochondria in muscle tissue of the chest, 7-day-old adult male Drosophilae were dissected in PBS, fixed with 3% formaldehyde in a fixation buffer (100 mM PIPES, 1 mM EGTA, 1% Triton X-100 and 2 mM MgSO4, pH 6.9) for 25 minutes, and washed with a washing buffer (50 mM Tris-HCl, 150 mM NaCl, 0.1% Triton X-100 and 0.5 mg/mL BSA, pH 6.8). Afterward, the resulting sample was fixed with a SlowFade™ Gold antifade reagent (Invitrogen), and photographed using a CarlZeiss confocal microscope (LSM710).
Afterward, to confirm the image of mitochondria in the motoneurons of a limb, 7-day-old adult male Drosophilae were dissected in PBS, and a front limb was fixed with 4% formaldehyde in a fixation buffer (100 mM PIPES, 1 mM EGTA, 1% Triton X-100 and 2 mM MgSO4, pH 6.9) for 25 minutes, washed with PBST, fixed with a SlowFade™ Gold antifade reagent (Invitrogen), followed by acquiring an image using a CarlZeiss confocal microscope (LSM710).
1-15. Blue Native Polyacrylamide Gel Electrophoresis (BN-PAGE)
Mitochondria were isolated from 14-day-old male adult Drosophilae using a mitochondrial isolation kit (Pierce) according to the manufacturer's protocols, and the purified mitochondria extract was resuspended in 60 μL of 1× Native PAGE sample buffer (Invitrogen) containing 2% n-dodecyl-β-D-maltoside (DDM), 1% Digitonin and a protease inhibitor (Halt). Subsequently, the sample was incubated on ice for 15 minutes and centrifuged at 12,000×g. A mitochondrial protein concentration in a supernatant was detected, and the supernatant (20 μg) was mixed with a 0.5% G-250 sample additive, followed by BN-PAGE using a 3% to 12% Native PAGE Bis-Tris gel (Invitrogen) at 4° C. Here, an anode running buffer was used for the outside of a gel, and a cathode running buffer was used for the inside of a gel. After PAGE, western blotting analysis was carried out with mouse anti-NDUFS3 (1:5000, Abcam), mouse anti-UQCRC2 (1:1000, Abcam), and mouse anti-ATP5A (1:10000, Abcam) antibodies.
1-16. Measurement of Mitochondrial Superoxide
Mitochondrial ROS generation in Drosophila was detected using a mitochondrial oxygen free radical indicator, mitoSOX-Red (Invitrogen), according to the manufacturer's protocol. More specifically, muscle tissue cut from the chest of 11-day-old Drosophila in cold PBS was incubated with 5 μM MitoSOX-Red in DMSO at 25° C. for 20 minutes, washed with cold PBS three times, the muscle tissue sample was rapidly fixed with a SlowFade™ Gold antifade reagent (Invitrogen), and then observed using a Carl Zeiss confocal microscope (LSM710) within 15 minutes. Here, fluorescence intensity was quantified using Image J software.
1-17. ATP Assay
To inhibit ATPase enzyme activity, the chests of 28-day-old Drosophilae were homogenized in 100 μL of an extraction buffer (6M Guanidine-HCl, 100 mM Tris, 4 mM EDTA, pH 7.8), an extract was immediately lyophilized in liquid nitrogen, and heated to denature an ATP synthase. Afterward, the sample was centrifuged at 20,000×g for 15 minutes, a supernatant was transferred to a new tube and diluted with an extraction buffer (1/100), the sample was added to each well of a 96-well plate and mixed with a luminescent solution of an Enliten ATP assay kit (Promega), and luminescence was measured using a Glomax microplate reader (Promega) every ten seconds. Afterward, a supernatant was diluted with an extraction buffer (1/2), and a protein concentration was measured using a BCA protein assay kit (Pierce). Afterward, the measured concentration was divided by the total protein concentration, thereby measuring a relative ATP level compared to the standard.
1-18. Protein Oxidation Assay
Protein oxidation detection was detected using an OxyBlot protein oxidation detection kit (Millipore) according to the manufacture's protocols. Specifically, the chests of 28-day-old Drosophilae were homogenized in a lysis buffer containing 6% SDS-containing 2% β-mercaptoethanol, the homogenate was centrifuged at 20,000×g for 30 minutes, followed by discarding pellet debris, and a denatured protein was derivatized with 2, 4-dinitrophenylhydrazine (DNPH) at 25° C. and neutralized with a neutralization solution. The DNPH-labeled protein was then subjected to SDS-PAGE, and transferred to a PVDF membrane (Millipore), and then the membrane was analyzed with an anti-DNP antibody (1:150, Millipore), a signal was detected using a goat anti-rabbit IgG HRP-conjugated secondary antibody (1:300; Millipore). Here, detection was carried out using an ECL-Plus kit (Amersham), and a band density was measured using the Image J software.
1-19. Nuclear/Cytoplasmic Fractionation Assay
Twenty heads of male Drosophilae were lysed in a nuclear extract kit reagent (Active Motif) according to the manufacturer's protocols, and protein extracts obtained from different cell fractions were mixed with a SDS loading buffer and heated, followed by western blotting analysis through SDS-PAGE.
1-20. Protein Solubility Assay
Total proteins were fractionated according to solubility using several modified protocols previously disclosed (Woo et al., 2017), and 20 heads of 7 to 14-day-old Drosophilae were homogenized in a lysis buffer without SDS (50 mM Tris-HCl, 150 mM NaCl, 5 mM EDTA, 0.1% NP-40, and 10% glycerol, pH 7.5). Subsequently, the homogenized sample was centrifuged at 100,000×g and 4° C. for 30 minutes, and a supernatant, as a soluble fraction, was obtained. In addition, the remaining pellet was additionally extracted with 50 μL of a 2× buffer containing 2% SDS and sonicated, followed by heating at 95° C. for 10 minutes. In this process, a supernatant was obtained into insoluble fractions.
1-21. GSH/GSSG Contents
The oxidized form (glutathione sulfide, GSSG) and reduced form of glutathione (GSH) were quantified using a glutathione assay kit (Cayman Chemical) according to the manufacturer's protocols, and more specifically, the total glutathione from 10 heads of 10-day-old Drosophilae was homogenized in 50 μL of 50 mM MES buffer, the sample was centrifuged at 10,000×g for 15 minutes, and a supernatant was transferred to a new tube. Afterward, the same amount of MPA reagent was added to the sample, and then the mixture was maintained at room temperature for 5 minutes. The mixture was centrifuged at 2,000×g for 2 minutes, and then vortexed as soon as 2.5 μL of TEAM reagent was added. Subsequently, the resultant was put into each well of a 96-well plate, and an MES buffer, a cofactor mixture, an enzyme mixture and a DTNB mixture were added. Afterward, 405 nm absorbance was measured using a Glomax microplate reader (Promega), 2.5 μL of TEAM reagent was added, an oxidized glutathione (GSSG) was measured using the same method as the total glutathione assay. In addition, 2-vinylpyridine was added, followed by incubation at 25° C. for 1 hour, and a supernatant was diluted in an extraction buffer (1/10) and then a protein concentration was measured using a BCA protein assay kit (Pierce) through the same method as the total glutathione assay. To obtain values obtained by calculating levels of the oxidized glutathione (GSSG) and the reduced glutathione (GSH), compared to the standard level, the obtained protein concentration was divided by a total protein concentration.
In this example, to confirm whether in vitro glutathionylation of a FUS protein occurs, the oxidized glutathione (glutathione disulfide, GSSH) was added to a myc-labeled human FUS recombinant full-length protein and incubated, separation through sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) was performed, and western blotting analysis was performed using a mouse anti-GSH antibody and a mouse anti-myc antibody.
As a result, as shown in
To confirm whether the glutathionylation of FUS protein occurs in vivo, a human FUS protein specifically expressed in neurons was expressed in Drosophila neurons using an elav-Gal4 driver. Specifically, a pCMV6-FUS-GFP-labeled human wild-type FUS protein was transfected into Drosophila. A region stained with DAPI represents the location of the nucleus.
As a result, the human wild-type FUS protein is located mainly in the nucleus of neurons of the brain of Drosophila, but as indicated by the arrows of
In this example, to confirm whether the glutathionylation of a human wild-type FUS protein and a human mutant FUSP525L protein occurs in a mammalian system, a human wild-type FUS protein and a human mutant FUSP525L protein were expressed (transfected) in a mouse neuroblastoma cell line Neuron2a (N2a). The region stained with DAPI represents the location of the nucleus.
As a result, as indicated by the arrows of
5-1. Confirmation of Location at which Glutathionylation of FUS Protein by Mass Spectrometry
In this example, to confirm a location at which glutathionylation in a human FUS protein occurs, in vitro glutathionylation of a myc-labeled human FUS protein was induced, and the glutathionylated human FUS protein was detected using a Coomassie stained gel. Afterward, a human FUS protein band was cut from the gel and digested with trypsin, followed by performing Matrix Assisted Laser Desorption/Ionization (MALDI)-mass spectrometry.
As a result, as shown in
5-2. Confirmation Whether of Sequence of RanBP2 Zinc-Finger Domain in FUS Protein is Conserved Between Species s
The RanBP2 zinc-finger domain of a FUS protein includes four cysteines. To confirm whether the cysteine sequence among the sequence of the RanBP2 zinc-finger domain is conserved in eukaryotes, the sequences of the RanBP2 zinc-finger domains of D. melanogaster, X. laevis, a zebrafish (D. rerio), a mouse (M. musculus) and a human (H. sapiens) were analyzed.
As a result, as shown in
6-1. Analysis of Solubility of Glutathionylated FUS
As confirmed in Examples 1 to 3, the glutathionylated human FUS protein aggregate is observed in the cytoplasm of neurons of the Drosophila brain, as confirmed in Example 5, glutathionylation occurs at Cys-447 of the RanBP2 zinc-finger domain in FUS proteins. Based on this example, to confirm whether the glutathionylation of FUS proteins affects the formation of FUS protein aggregates, an experiment of measuring the solubility of a glutathionylated FUS protein was carried out. Specifically, as shown in
As a result, as shown in
In addition, as a result of measuring the solubility of the soluble fraction of the glutathionylated human FUS protein under the above-described conditions by adding the oxidized glutathione (glutathione disulfide, GSSH), it was confirmed that the degree of solubility dramatically decreased from 90% to 20%.
Summarizing the above result and the result of Example 5, it was confirmed that the glutathionylation of a FUS protein induces the formation of a FUS protein aggregate.
6-2. Analysis of Three-Dimensional Homologous Model of RanBP2 Zinc-Finger Domain of FUS
To obtain the structural basis for the relative location of the Cys-447 residue, the three-dimensional homology model of the RanBP2 zinc-finger domain in a human FUS protein was created using an I-TASSER server, and the RanBP2 zinc-finger domain model was used to search for a protein having a structurally homologous region in the protein database bank (PDB).
As a result, as shown in
Glutathionylation is a result of a disulfide bond between a cysteine and reduced glutathione (GSH), which is known to lead to changes in the structure and function of a protein.
To confirm whether FUS glutathionylation occurs, as a result of analyzing in vitro glutathionylation, as shown in
In addition, to confirm in vivo FUS glutathionylation, human FUS specifically expressed in neurons were expressed in Drosophila neurons using an elav-Gal4 driver.
As a result, as indicated by the white arrows of
Subsequently, to confirm whether the glutathionylation of FUS and its mutant FUSP252L also shows the above-described result in a mammalian system, as a result of expressing human FUS and FUSP525L in a mouse neuroblastoma cell line, Neuron2a (N2a), as shown in
Therefore, it was confirmed that FUS and FUSP525L are glutathionylated both in vitro and in vivo.
Finally, to identify a glutathionylation site, the glutathionylation of myc-tagged human FUS was induced in vitro, and a band was detected using a Coomassie stained gel. The FUS protein band was cut from the gel, digested with trypsin and subjected to analysis through MALDI-mass spectrometry.
As a result, as shown in
In addition, the FUS sequence relating to cysteine conservation in eukaryotes was investigated, confirming that all four cysteines are well conserved from flies to humans, and among these, a glutathionylation site in the RanBP2-type ZnF domain, Cys-447, (
Therefore, it was confirmed that human FUS is specifically glutathionylated at the Cys-447 residue
Post-translational modification is known as a main mediator in pathogenic protein aggregation in various neurodegenerative diseases including amyotrophic lateral sclerosis (ALS). As shown in
To confirm whether FUS glutathionylation at the Cys-477 residue regulates the aggregation of a FUS protein, a solubility test for FUS was carried out.
More specifically, glutathionylation was induced by addition and incubation of the myc-tagged human FUS protein purified from HEK293 cells along with GSSG, and exposed to heat shock to give protein toxic stress (see
FUS solubility was evaluated by quantifying FUS proteins in fractions of the supernatant and pellet of each sample through western blotting analysis at different points of time.
As a result, as shown in
This shows that FUS glutathionylation significantly induces the formation of an aggregate, and the FUS glutathionylation of the Cys-447 residue induces protein aggregation, and as a main determinant for the formation of FUS aggregates, a hypothesis that can support cysteine glutathionylation can be proven.
In addition, to further evaluate the structural basis on the relative location of Cys-447 residue, a three-dimensional homology model of the human FUS ZnF domain was created using I-TASSER server, and the FUS ZnF domain model was used to search for a protein having a structurally homologous region in the PDB.
As a result, as shown in
To reduce pathology caused by glutathionylated FUS, an exact molecular mechanism and a protein, which can regulate a glutathionylation process was intended to be identified, and omega class glutathione transferase (GSTO) was selected as a potential candidate.
According to previous reports, human GSTO1 is known to serve as a deglutathionylation enzyme, and the inventors reported previously that GstO2, which is a Drosophila homologous chromosome of the human GSTO1, inhibits neurotoxicity by regulating the glutathionylation of the 13 subunit of ATP synthase in a Drosophila PD model (Kim et al., 2012).
Based on the above background knowledge, the inventors used Drosophila as a genetic tool to identify a novel role and regulatory factor for glutathionylation in the pathogenesis of ALS induced by FUS. First, it was intended to confirm whether increased GstO2 can reduce phenotypes caused by the overexpression of human FUS in Drosophila.
More specifically, to evaluate the functional relationship between GstO2 and FUS in Drosophila, transformed Drosophila exhibiting GstO2 overexpression and eye-specific Gal4 or GMR-Gal4-induced FUS expression was produced.
Meanwhile, according to a recent study using a Drosophila genetic approach, FUS expression in the eyes of an adult insect is known to exhibit a rough eye phenotype, and like a previous report, FUS expression showed a rough eye phenomenon, and it was confirmed that ommatidial tissue was disrupted.
However, it was confirmed that coexpression of FUS and GstO2 significantly recovers a rough eye phenotype, and a change in disrupted eyes was not found in a fly only expressing GstO2 (
Next, to confirm the locomotive activity defect mechanism by FUS expression using pan-neuronal Gal4 and elav-Gla4, a larval crawling assay was performed to investigate the locomotive activity of larvae expressing FUS in neurons.
As a result, as shown in
From these results, the inventors investigated the number of synaptic boutons at a neuron muscular junction (NMJ) to confirm whether a larval locomotive activity defect results from a defect in the NMJ.
As a result, as shown in
In addition, as shown in
Meanwhile, a negative geotaxis assay is an assay for evaluating the dysfunction of the nervous system in research on various neurodegenerative diseases including ALS, and as a result of applying it to the Drosophila model system according to the present disclosure, as shown in
Therefore, from the data, it was confirmed that FUS-induced neurotoxicity can be remarkably inhibited or reinforced through the regulation of GstO2 expression.
It is known that abnormal mitochondria are consistently observed in animal models of ALS (Dal Canto and Gurney, 1994; Magrane et al., 2014). In addition, the overexpression of mutant FUS in motoneurons led to mitochondrial division (Tradewell et al., 2012), the expression of wild-type and mutant FUS in NSC34 motoneurons reduced mitochondrial ATP production (Stoica et al., 2016). Although mitochondrial dysfunction remains a common feature of ALS in various previous studies, it has not yet been proven that, in FUS-induced proteinopathy, mitochondrial dynamics and the dysfunction of the oxidative phosphorylation (OXPHOS) system are the major causes for ALS pathology. Therefore, the inventors confirmed in previous research that mitochondrial division is reinforced in muscles or motoneurons in FUS-expressing flies, and Mail instability caused by a mitochondrial fusion protein results in unbalanced mitochondrial dynamics (Altanbyek et al., 2016).
On the basis of the above research results, it was intended to confirm whether GstO2 expression induces mitochondrial division in FUS-expressing flies, and to this end, the GstO2 effect on thoracic muscles in FUS-expressing flies was characterized.
To characterize the GstO2 effect, a FUS-expressing Drosophila line were crossed with muscle-specific Gal4 and Mhc-Gal4, and then the mitochondria were visualized by expression of mitochondria-targeted GFP (mitoGFP).
As a result, as shown in
Subsequently, to confirm whether GstO2 restores mitochondrial morphology in motoneurons, GstO2 was overexpressed using motoneuron-specific Gal4 and D42-Gal4, along with mitoGFP.
As a result, as shown in
In addition, it was investigated whether mitochondrial division was caused by the dysfunction of a protein that regulates mitochondrial dynamics. The inventors confirmed in previous research that Marf expression reduced in FUS-expressing flies induces excessive division of mitochondria (Altanbyek et al., 2016), and evaluated whether the Marf expression is changed by GstO2.
As a result, as shown in
Subsequently, to confirm whether the morphological change of the mitochondria in FUS overexpression affects the OXPHOS system, the functional relevance of unbalanced mitochondrial dynamics in FUS-induced ALS was evaluated. More specifically, the content of a mitochondria complex was measured in the electron transport chain (ETC) indirectly measured by analyzing levels of various complex subunits of the FUS-expressing flies.
As a result, as shown in
To further research a complex assembly, blue native gel electrophoresis (BN-PAGE) was performed on the mitochondria purified from thoracic tissue in adult flies.
As a result, as shown in
Subsequently, to confirm whether GstO2 can restore mitochondrial functionality, the mitochondrial production of reactive oxygen species (ROS) FUS-expressing flies was measured using mitoSOX.
As a result, as shown in
In addition, the mitochondria produce cellular energy in the form of ATP, and it was confirmed that the ATP level is remarkably reduced in the FUS-expressing flies compared to the control (
The amount of an oxidized protein in the cytoplasm was measured to confirm whether GstO2 can reduce an increase in oxidative stress in the cytoplasm.
As a result, as shown in
Therefore, it was confirmed that FUS-induced oxidative stress in the cytoplasm and unbalanced dynamics and the dysfunction of the mitochondria are remarkably prevented by GstO2.
The above results that confirm that all defective phenotypes caused by FUS expression in Drosophila are suppressed by GstO2 overexpression show that GstO2 can promote a decrease in FUS, which is a pathogen, in neurons.
Therefore, to confirm the effect of inhibiting the formation of a FUS aggregate in GstO2-mediated Drosophila neurons, according to the immunoblotting result for the brain extract of a FUS-expressing adult fly, it was confirmed that coexpression of GstO2 does not affect a FUS level (see
Subsequently, to confirm whether GstO2 expression inhibits FUS mislocalization in brain tissue, nuclear/cytoplasmic fraction analyses were performed to measure FUS levels in the cytoplasm and nucleus.
As a result, as shown in
To further examine the effect of GstO2 on FUS aggregation in transgenic flies, fly heads of various genotypes were collected, and after dissolution in a modified lysis buffer, they were separated into detergent-soluble and insoluble fractions.
As a result, as shown in FIG.
On the other hand, as shown in
Therefore, it is shown that GstO2 in the GstO family has a protective function in FUS-induced ALS by regulating the formation of a FUS aggregate in the cytoplasm.
The increased FUS expression in the cytoplasm is known to promote the binding of FUS and the mitochondria, and induce mitochondrial dysfunction (Deng et al., 2015), and to confirm whether GstO2 regulates the FUS level of the mitochondria, after coexpression of FUS and GstO2 in fly muscle tissue, the FUS level from the purified mitochondria was assessed by western blotting.
As a result, as shown in
GstO2-mediated recovery of phenotypes of FUS-expressing flies may be involved in FUS glutathionylation, and therefore, the inventors hypothesized that GstO2 can regulate FUS glutathionylation and aggregation in the Drosophila brain, and to confirm this, the following experiments were performed.
First, as a result of a double immunofluorescence assay on the brain tissue of a FUS-expressing adult fly, as shown in
From the above, it was predicted that GstO2-mediated deglutathionylation of FUS inhibits the formation of FUS aggregates in the cytoplasm of neurons, and is effectively used to delay FUS-mediated neurotoxicity.
Subsequently, it was investigated whether endogenous GstO2 interacts with FUS in neurons. As a result, as shown in
According to previous research, FUS mutations have been identified in most ALS patients (Mackenzie et al., 2010), the FUSP525L variant shows cytoplasmic mislocalization and involvement in acute FUS-induced-ALS (Sun et al., 2011), FUS wild type and its variant FUSP525L are known to exhibit the same phenotypes such as rough eyes and decreased locomotive activity in Drosophila (Chen et al., 2016; Jackel et al., 2015).
Based on the result of confirming FUSP525L glutathionylation in the cytoplasm of neuro2a in
More specifically, to confirm whether GstO2 expression can inhibit FUSP525L-induced locomotive defects, a FUS mutant type FUSP525L was expressed in neurons using elav-Gal4, and an experiment of confirming larval locomotive activity was performed. Here, the FUSP525L mutation did not exhibit higher toxicity than wild-type FUS.
As a result, as shown in
Subsequently, the effect of GstO2 on FUSP525L solubility was intended to be confirmed. As a result, as shown in
Overall, it was confirmed that GstO2 regulates FUSP525L toxicity through the formation of a protein aggregate.
To confirm that the recovery effect of GstO2 on FUS-induced neurotoxicity is also applied to a mammalian system, a stable N2a cell line expressing a Myc-DDK-GSTO1 fusion protein for GSTO1, which is a human homologous chromosome of GstO2, was developed (see
As a result, as shown in
Subsequently, based on previous research results showing that the increased expression of FUS promotes apoptosis in mammalian neurons (Deng et al., 2015), to investigate the effect of GSTO 1 on FUS-induced apoptosis, N2a cells were identified by staining with an anti-cleaved caspase-3 antibody.
As a result, as shown in
Therefore, it was confirmed that the expression of GSTO1, which is a human homologous chromosome of GstO2, also improves FUS insolubility and FUS-induced cell apoptosis in mammalian neuron models of ALS.
It should be understood by those of ordinary skill in the art that the above description of the present disclosure is exemplary, and the exemplary embodiments disclosed herein can be easily modified into other specific forms without departing from the technical spirit or essential features of the present disclosure. Therefore, the exemplary embodiments described above should be interpreted as illustrative and not limited in any aspect.
ALS can be early diagnosed using a marker composition for diagnosing a neurodegenerative disease, which includes a glutathionylated FUS protein, according to the present disclosure, and a pharmaceutical composition for preventing or treating a neurodegenerative disease, which includes a GSTO gene or a protein encoding the gene as an active ingredient, may be used in treatment of ALS.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10-2018-0137289 | Nov 2018 | KR | national |
| 10-2018-0137404 | Nov 2018 | KR | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/KR2018/013820 | 11/13/2018 | WO | 00 |
