Mitochondria-associated endoplasmic reticulum membrane (MAM): roles in innate immunity dysregulation

Mitochondria-associated endoplasmic reticulum membrane (MAM), which serves as a signaling hub for interactions between the endoplasmic reticulum (ER) and mitochondria, dynamically coordinates innate immune processes by regulating calcium homeostasis, lipid metabolism, mitochondrial dynamics, mitochondrial protein modifications, and autophagy. MAM regulates calcium homeostasis to govern mitochondrial energy metabolism and inflammasome activation; maintains lipid metabolism for membrane integrity to support antiviral signaling pathways; controls mitochondrial fission and fusion dynamics, processes that are closely associated with mitochondrial DNA (mtDNA) release; regulates mitochondrial protein modifications to fine-tune the function of proteins localized at MAM; and facilitates the clearance of damaged mitochondria and leaked mtDNA through autophagy. Most critically, MAM dysfunction and innate immune dysregulation form a vicious cycle: immune activation disrupts MAM integrity, and MAM abnormalities exacerbate the release of mitochondrial damage-associated molecules, continuously driving overactivation of pathways such as inflammasomes and the cyclic GMP-AMP synthase (cGAS)-stimulator of interferon genes (STING) pathway, thereby promoting the development of autoimmune diseases. This review synthesizes current literature on the molecular mechanisms by which MAM regulates innate immunity. We summarize how disruptions in MAM-mediated mitochondrial homeostasis contribute to innate immune imbalance. By integrating these findings, we highlight potential intervention nodes. This underscores the clinical relevance of targeting MAM in immune-related pathological conditions.