Mitochondrial division and fusion in metabolism

Abstract

Mitochondria govern many metabolic processes. In addition, mitochondria sense the status of metabolism and change their functions to regulate energy production, cell death, and thermogenesis. Recent studies have revealed that mitochondrial structural remodeling through division and fusion is critical to the organelle's function. It has also become clear that abnormalities in mitochondrial division and fusion are linked to the pathophysiology of metabolic diseases such as diabetes and obesity. Here, we discuss the current understanding of the mechanisms of mitochondrial dynamics and their role in cellular and organismal metabolism.

Figure 1. Mitochondrial morphology is regulated by division and fusion

Mitochondria continuously divide and fuse and control their morphology. Mitochondrial division is initiated by recruitment of cytosolic Drp1 to the mitochondrial outer membrane by Drp1 receptors. On mitochondria, Drp1 assembles into helical filaments, wrapping around mitochondrial tubules. Drp1 filaments constrict and divide mitochondria, working together with ER tubules and actomyosin filaments. Mitochondrial fusion consists of outer membrane fusion and inner membrane fusion. Outer membrane fusion is mediated by mitofusin while inner membrane fusion is mediated by Opa1. Mitochondrial fusion is regulated by proteosomal degradation of mitofusins, proteolytic processing of Opa1 and production of GTP.