Stress Induced Mitochondrial Hyperfusion (SIMH)

A Concise Review on SIMH in Neurodegenerative Disorders and Other Diseases

Abstract

Mitochondria are critical for cell health, and damaged or dysfunctional mitochondria have been strongly linked to various human diseases, particularly neurodegenerative disorders. Mitochondrial function is regulated by several mechanisms, including the regulation of mitochondrial shape, size, number, and morphology. Mitochondria constantly fuse together and separate apart, and this fusion and fission process is known as mitochondrial dynamics. These mitochondrial dynamics are modulated in response to various stimuli, and recent reports have demonstrated that mitochondria undergo hyperfusion under mild to moderate stress conditions, resulting in the formation of elongated filaments. This phenomenon is referred to as stress induced mitochondrial hyperfusion (SIMH). SIMH is associated with enhanced protection of mitochondria and improved cell viability under stress conditions. The induction of hyperfusion can be triggered by diverse stressors, each with distinct and unique mechanisms. This mini review will focus on these stressors and their corresponding mechanisms, as well as the subsequent effects on mitochondrial and cell health. Additionally, disease models which demonstrate a correlation between specific disease-related stress conditions and mitochondrial hyperfusion are discussed.