Mitochondria and Endoplasmic Reticulum Contact Site as a Regulator of Proteostatic Stress Responses in Neurodegenerative Diseases

ABSTRACT Recent evidence indicates that the mitochondria–endoplasmic reticulum (ER) contact site is a novel microdomain essential for cellular homeostasis. Various proteins are accumulated at the mitochondria‐associated membrane (MAM), an ER subcomponent closely associated with the mitochondria, contributing to Ca2+ transfer to the mitochondria, lipid synthesis, mitochondrial fission/fusion, and autophagy. These functions are disrupted in the diseases, particularly in neurodegenerative diseases such as amyotrophic lateral sclerosis (ALS) and Alzheimer's disease. In this review, we summarize the disruption of protein homeostasis in various neurodegenerative diseases, present recent works on the mechanisms of MAM aberration, including ours mainly focused on ALS, and then discuss challenges and prospects for future MAM‐targeted therapies in neurodegenerative diseases.