NSF Award
2329634
Cells are the building blocks of tissues and must communicate effectively in order for tissues and organisms to form and function. One compartment of vertebrate cells critical for cell communication is the primary cilium, a slender projection on almost all cells that functions as a cellular antenna. While it is clear that primary cilia are critical for cellular communication, how cilia participate in cellular communication is not well understood. The cilium is challenging to functionally or physically isolate. The complete loss of cilia results in a loss of all ciliary signaling; a complete loss of proteins enriched in cilia leads to a loss of the cellular and ciliary pools of that protein. Thus, deciphering what is happening within the cilium versus the cell body is murky. The Caspary Lab developed genetic tools to isolate function of one ciliary protein specifically within cilia; the Mick and Wachten labs have complementary expertise in defining the protein composition within the cilium and manipulating signaling specifically within cilia, respectively. This collaborative research will combine the skills of the 3 labs to train and exchange students in investigating the signaling within cilia. At Emory, this project will involve students in cohort-based, structured research experiences that will train the students in research along with ethics and scientific presentation. This project will benefit society by providing bona fide research experiences to a broad swath of students and, through exchange, expose them to a diverse array of techniques to address the fundamental question of how cilia mediate cell communication.<br/><br/>Cyclic AMP (cAMP) signaling is a central messenger for ciliary signaling. Components of the cAMP signaling cascade are enriched in primary cilia, generating a functionally separate cAMP compartment. Recent reports demonstrate that aberrant localization of ciliary cAMP signaling components alters ciliary signaling. However, how the cell distinguishes between ciliary and cytoplasmic cAMP signaling outputs and which signaling pathways and cellular cues are specifically engaged by ciliary versus cytoplasmic cAMP signaling is not known. ARL13B is a regulatory GTPase highly enriched in cilia. The Caspary Lab engineered a cilia-excluded variant of ARL13B and showed that it retains its known biochemical activities to enable the isolation of ciliary ARL13B function. In this research, the Caspary, Mick, and Wachten labs will investigate whether loss of ARL13B in the primary cilium controls ciliary cAMP signaling in a kidney epithelial cell line. Aim 1 will unravel the ciliary cAMP “signature” in cells expressing only cilia-excluded ARL13B. Aim 2 will optogenetically stimulate cAMP signaling within normal and Arl13B-excluded cilia to define the common RNA and protein composition. Aim 3 will investigate the role of ciliary cAMP signaling in remodeling morphology of cells lacking ciliary ARL13B through use of 3D cultures. Finally, Aim 4 will manipulate the phospholipid composition of the ciliary membrane to determine whether it regulates ciliary cAMP/ARL13B-signaling within cilia. Through this research, the role of signaling within the primary cilium will be deciphered at unprecedented resolution.<br/><br/>This collaborative US/Germany project is supported by the US National Science Foundation and the Deutsche Forschungsgemeinschaft (DFG).<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.
