Novel roles of C1q tumor necrosis factor-related proteins (CTRPs) in relaxin receptor biology

点击翻译按钮获取中文摘要

I study the role of relaxin receptor and binding partners on cell differentiation. My lab established relaxin (RLX) and INSL3 as novel mediators of cell motility and extracellular matrix (ECM) invasion. We also demonstrated a new function of Insl5, another relaxin-like peptide, in glucose homeostasis in mice and identified enteroendocrine cells of the human and mouse large intestine as specific producers of INSL5. Recently, my lab discovered a new binding partner to relaxin receptor RXFP1. The secreted C1qTNF-related peptide CTRP8 protein is structurally distinct from RLX. CTRP8 binds to RXFP1 and activates signaling pathways resulting in enhanced cell migration and matrix invasion. This proposal is a continuation of my pioneering CTRP8-RXFP1 work and uses molecular modelling and targeted mutagenesis to identify specific CTRP8 residues important for the binding of RXFP1. I use in-vivo labeling to capture novel binding factors to intracellular domains of RXFP1 that trigger CTRP8-induced signaling events. We were the first to show a novel role of CTRP8-RXFP1 in the protection against DNA damage by increased expression and activity of defined DNA repair proteins. I will expand on this finding and determine the impact of CTRP8-RXFP1 on oxidative stress responses which occur frequently in cells. I will measure mitochondrial production of reactive oxidative radicals (ROS), assess mitochondrial genes, and quantify ROS-induced oxidative DNA base lesions using 3D nuclear imaging, mitochondrial gene expression profiling and protein analysis. I showed that CTRP8-RXFP1 engages STAT3 signaling and increases the expression of key proteins promoting DNA repair and cell survival. I will study the molecular mechanisms by which CTRP8-RXFP1 promotes cell survival and mutagenic DNA damage repair. My lab has compelling evidence implicating CTRP1, a close relative of CTRP8, as a new RXFP1 agonist. CTRP1 and CTRP8 share the RXFP1 binding domain and we showed that CTRP1 requires RXFP1 to enhance cell motility and activate specific signaling pathways. The broad tissue expression of CTRP1 may have important implications for RXFP1 signaling in tissues. Like for CTRP8-RXFP1, we will demonstrate the physical CTRP1-RXFP1 interaction and identify the role of CTRP1 in cell motility, matrix invasion and DNA protection. We use new Ctrp1 mouse strains (overexpressing and KO) to assess the protective functions of Ctrp1-Rxfp1 in bleomycin-induced lung fibrosis. We employ our ocular wound healing mouse model and determine the ability of CTRP1 and CTRP8 to repair ocular surface lesions. My proposal will generate key advances in this exciting emerging field of RXFP research and, for the tenure of this grant, will provide training opportunities for a total of three graduate students and up to five summer/COOP students.