NSF Award
2321487
This Mid-Career Advancement (MCA) award investigates the physiological mechanisms behind the crustacean growth process referred to as molting. The molting process allows growth in crustaceans (a group that includes crabs and shrimp), and is an intricately regulated process involving coordinated signals between at least two endocrine glands, the crustacean sinus gland/X-organ in the eyestalk and the Y-organ. The endocrine signals work through changes in gene expression, resulting in specific tissues being transformed into different cellular phenotypes, expressed through the resulting protein complement or proteome. In this project, the proteome of these tissues at different stages of molting will be characterized in two crab species to understand the complex signaling and endocrine control processes involved. The proteome is only accessible through a multi-step analytical pathway, requiring advanced mass spectrometry. The award provides protected time for the principal investigator to expand his skills to operate an advanced mass spectrometer and subsequently teach undergraduate and master’s level graduate students how to operate it. The application of mass spectrometers to analyze the proteomes of a wide range of organisms is advancing our knowledge of how the changing environment affects multiple economically important organisms. For example, the results from this work will advance understanding of the growth process of crustaceans and insects, because the molecular processes are similar in these two organismal groups, which are important for aquaculture and agriculture. The PI will apply his expertise to train other investigators and a new generation of students to extend proteomic analyses to a wide range of organisms and to build new collaborations. <br/><br/>Crustacean molting is a cyclical event which replaces the carapace with a new exoskeleton that expands before it hardens, allowing the animal to grow. This process is suppressed during intermolt by the inhibition of ecdysteroidogenesis in the Y-organ (YO) by molt inhibiting hormone (MIH), which is produced by the sinus gland/X-organ in the eyestalk. Decreasing levels of MIH shift the YO from intermolt to premolt and increase its capacity to synthesize ecdysteroids to initiate the molt (ecdysis). The investigators hypothesize that this shift is controlled through mechanistic Target Of Rapamycin (mTOR), a Serine/Threonine-specific protein kinase, via a cyclic GMP-activated protein kinase (PKG). Using recombinant MIH on YOs in vitro with and without a PKG inhibitor, the research will test whether MIH signaling via PKG affects mTOR activity. When it is not inhibited, mTOR affects the transforming growth factor beta family of transcription factors, which shift the YO towards the committed state when it is refractory to MIH. Finally, the expression of ecdysteroid receptors and ecdysteroid responsive genes in the YO itself suggests that it is autoregulated by ecdysteroidogenesis when it shifts towards the repressed state. The investigators will also use the removal of the sinus gland/X-organ, which stops MIH secretion, and multiple leg autotomy, which initiates ecdysis, to experimentally manipulate molting. The principal investigator will characterize how the manipulations will affect the proteome of the Y-organ with the help of mass spectrometry.<br/><br/>This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.
