Compartmentalized cAMP signaling in reactive astrocytes

PROJECT SUMMARY Glaucoma is the leading cause of irreversible blindness and along with other optic neuropathies is characterized by the loss of retinal ganglion cells (RGCs). Increased intraocular pressure (IOP) management is the current standard of care for glaucoma patients, but fails to stop the irreversible loss of RGCs and progressive visual dysfunction. Glaucomatous RGC death was recently found to be driven by reactive optic nerve head (ONH) astrocytes, suggesting targeting these (and other) glial populations in the retina may be a viable strategy to protect RGCs. We recently discovered nuclear and cytoplasmic pools of cAMP, dependent on expression of soluble adenylyl cyclase (sAC), and associated with the stress-induced cell cycle inhibitor p21Cip, differentially regulate reactive astrocyte proliferation, microglial/macrophage activation, and RGC survival after traumatic optic nerve injury. Here, using a newly developed and reversible model of glaucoma in mice, we will establish the molecular, cellular, and transcriptional mechanisms that confer specificity to neurotoxic and protective astrocyte reactivity regulated by compartmented cAMP, sAC, and p21Cip in ONH astrocytes and Muller glia. An exciting element of our proposal is the use of state-of-the-art single cell RNA sequencing and cut-and-tag assays to identify the transcriptional and (epi)genetic changes induced by compartmented cAMP manipulation, and link those changes to reactive phenotypes in astrocytes and downstream effects on RGC survival and microglial/macrophage infiltration. All of this will be accomplished using novel AAV viral vectors to specifically target ONH astrocytes and Muller glia. These experiments will lead to the discovery of new biological pathways that regulate glial reactivity in neurodegenerative disease, and serve in the development of gliotheraputics for the treatment of glaucoma and other optic neuropathies.