The Cellular Stress Response Interactome and Extracellular Matrix Cross-Talk during Fibrosis: A Stressed Extra-Matrix Affair

Abstract

Diverse internal and external pathologic stimuli can trigger cellular stress response pathways (CSRPs) that are usually counteracted by intrinsic homeostatic machinery, which responds to stress by initiating complex signaling mechanisms to eliminate either the stressor or the damaged cells. There is growing evidence that CSRPs can have context-dependent homeostatic or pathologic functions that may result in tissue fibrosis under persistence of stress. CSRPs can drive intercellular communications through exosomes (trafficking and secretory pathway determinants) secreted in response to stress-induced proteostasis rebalancing. The injured tissue environment upon sensing the stress turns on a precisely orchestrated network of immune responses by regulating cytokine-chemokine production, recruitment of immune cells, and modulating fibrogenic niche and extracellular matrix (ECM) cross-talk during fibrotic pathologies like cardiac fibrosis, liver fibrosis, laryngotracheal stenosis, systemic scleroderma, interstitial lung disease and inflammatory bowel disease. Immunostimulatory RNAs (like double stranded RNAs) generated through deregulated RNA processing pathways along with RNA binding proteins (RBPs) of RNA helicase (RNA sensors) family are emerging as important components of immune response pathways during sterile inflammation. The paradigm-shift in RNA metabolism associated interactome has begun to offer new therapeutic windows by unravelling the novel RBPs and splicing factors in context of developmental and fibrotic pathways. We would like to review emerging regulatory nodes and their interaction with CSRPs, and tissue remodeling with major focus on cardiac fibrosis, and inflammatory responses underlying upper airway fibrosis.