Development of Tissue-Specific Properties in Central Nervous System Mural Cells - PROJECT SUMMARY/ABSTRACT Mural cells, encompassing pericytes and vascular smooth muscle cells, line blood vessels and regulate vessel development, stability, and tone. In the central nervous system (CNS), mural cells have additional, specialized functions: they regulate the blood-brain barrier, mediate neurovascular coupling, produce neurotrophic factors, and contribute to molecular transport and metabolism. CNS mural cells are dysfunctional in neurological disorders including Alzheimer’s disease, cerebral small vessel diseases, and diabetic retinopathy. Reflective of their functional specializations, CNS mural cells have gene expression profiles distinct from mural cells of other organs, a phenomenon termed organotypicity. Despite their importance to CNS homeostasis, we have virtually no knowledge of how these specialized properties arise during CNS mural cell development. CNS mural cells have two distinct developmental origins (neural crest in retina and forebrain, mesoderm in other regions), but converge on a remarkably similar molecular profile. This observation suggests that extrinsic signals from neural tissue control the development of organotypic properties. Further, a novel analysis of transcriptional and epigenomic data suggest that Wnt/β-catenin signaling and the transcription factors ZIC1 and ZIC4 are key regulators of this process. Therefore, the proposed project will test the hypothesis that neural tissue-derived Wnt/β-catenin signaling drives expression of ZIC transcription factors, which activates a CNS-specific gene regulatory network in mural cells that mediates their specialization. In Aim 1, genetic mouse models will be used to test whether Wnt/β-catenin signaling is necessary and sufficient to achieve CNS-specific molecular and functional properties in mural cells. Similarly, in Aim 2, genetic mouse models will be used to evaluate whether ZIC1 and ZIC4 are required for development of organotypic properties in CNS mural cells. In Aim 3, transcription factor CUT&RUN and chromatin accessibility profiling will be used to define the gene regulatory network and cis-regulatory elements controlling CNS mural organotypicity. Together, the proposed work will advance our understanding of the molecules and signaling networks that govern CNS mural cell development, which could ultimately be leveraged to develop therapeutic strategies facilitating CNS mural cell survival or regeneration in pathological conditions. The proposed research project also serves as the basis for a postdoctoral fellowship training plan, through which Dr. Benjamin Gastfriend (applicant) will receive mentored training from Dr. Richard Daneman (sponsor) and Dr. Christopher Glass (co-sponsor) at the University of California, San Diego. Training in rigorous research using genetic mouse models, epigenomic techniques, and in skills necessary to lead research in an academic setting will synergize with the applicant’s graduate research and training, and prepare Dr. Gastfriend to make future contributions to biomedical research.
