Organelle Contact Sites

Mitsuo Tagaya, Kohei Arasaki, Tagaya, Mitsuo, Arasaki, Kohei

Mitochondria are powerhouses and central to metabolism in cells. They are highly dynamic organelles that continuously fuse, divide, and move along the cytoskeleton to form the mitochondrial network. The fusion and fission are catalyzed by four dynamin-related GTPases in mammals that are controlled by a variety of protein-protein interactions and posttranslational modifications. Mitochondrial dynamics and metabolism are linked and regulate each other. Starvation induces mitochondrial elongation, which enables the mitochondria to produce energy more efficiently and to escape from autophagic degradation. Damaged portions of mitochondria are removed from the healthy parts by division, and subsequently degraded via a specific mode of autophagy termed mitophagy. Recent studies shed light on the contribution of the endoplasmic reticulum to mitochondrial dynamics and the cooperation of the two organelles for the progression of autophagy including mitophagy. A subdomain of the endoplasmic reticulum apposed to mitochondria is called the mitochondria-associated membrane (MAM), which comprises a unique set of proteins that interact with mitochondrial proteins. Here we review our current understanding of the molecular mechanisms of mitochondrial dynamics and mitochondria-related processes in the context of the interaction with the endoplasmic reticulum.