Figure 1.

Higd1a, as a mitochondrial inner protein, plays important roles in various physiological and pathophysiological processes. Higd1a has two transmembrane domains with a loop-like structure inside of mitochondrial inner membrane and both its N-terminal and C-terminal are presented outside of mitochondrial inner membrane. Higd1a is involved in multiple physiological processes, such as inhibiting apoptosis of the cells, facilitating electron transport chain (ETC) assembly, maintaining mitochondrial homeostasis, regulating the function of reproduction system and the development of nervous system. In pathophysiological processes, Higd1a exhibits diverse roles in regulating tumor growth, displays protective roles against hepatic lipotoxicity, diabetes and mitochondrial diseases. It is known that the roles of Higd1a in the processes of hepatic lipotoxicity, tumor growth and diabetes are hypoxia-dependent, which have been labeled by “∗”. However, whether the functions of Higd1a in other processes, which are not labeled with “∗”, are hypoxia-dependent or not needs further investigation. MOM: mitochondria outer membrane; MIM: mitochondria inner membrane.