Tmem63c, a member of the TMEM63 family proteins, functions as a calcium-permeable channel preferentially activated by hypo-osmolality [1]. It has been implicated in multiple physiological functions and is associated with pathways related to osmoregulation, cell viability, and organelle morphology regulation. Its importance lies in its role in maintaining normal physiological states and preventing diseases [1,2,3]. Genetic models, such as mouse models, are valuable for studying Tmem63c.

Biallelic variants in the Tmem63c gene cause mitochondrial morphology defects and underlie hereditary spastic paraplegias, with some cases associated with mild intellectual disability. Biochemical and microscopy analyses show that Tmem63c is an endoplasmic reticulum-localized protein, enriched at mitochondria-endoplasmic reticulum contact sites, indicating its role in regulating endoplasmic reticulum and mitochondrial morphologies [2]. In human podocytes, siRNA-mediated down-regulation of Tmem63c diminishes cell viability, protein kinase B (Akt) signaling, and increases apoptosis, suggesting it is a potential pro-survival factor [3]. Also, miR-564 reduces Tmem63c expression in human embryonic kidney 293 cells (HEK 293) and human podocytes, and TGF-β treatment increases its expression. Reduced Tmem63c expression is associated with changes in epithelial-mesenchymal transition (EMT) marker proteins in HEK 293 and decreased nephrin expression in human podocytes, along with reduced cell viability in HEK 293 [4].

In conclusion, Tmem63c is crucial for maintaining cell viability, regulating organelle morphologies, and may be involved in EMT processes. Mouse models and in-cellula studies have revealed its role in hereditary spastic paraplegia and podocyte function, contributing to our understanding of motor neuron degenerative diseases and renal diseases [2,3,4].

References:

1. Qin, Yuqi, Yu, Daqi, Wu, Dan, Shi, Yun Stone, Dang, Shangyu. 2023. Cryo-EM structure of TMEM63C suggests it functions as a monomer. In Nature communications, 14, 7265. doi:10.1038/s41467-023-42956-2. https://pubmed.ncbi.nlm.nih.gov/37945568/

2. Tábara, Luis Carlos, Al-Salmi, Fatema, Maroofian, Reza, Prudent, Julien, Baple, Emma L. . TMEM63C mutations cause mitochondrial morphology defects and underlie hereditary spastic paraplegia. In Brain : a journal of neurology, 145, 3095-3107. doi:10.1093/brain/awac123. https://pubmed.ncbi.nlm.nih.gov/35718349/

3. Eisenreich, Andreas, Orphal, Miriam, Böhme, Karen, Kreutz, Reinhold. 2020. Tmem63c is a potential pro-survival factor in angiotensin II-treated human podocytes. In Life sciences, 258, 118175. doi:10.1016/j.lfs.2020.118175. https://pubmed.ncbi.nlm.nih.gov/32750436/

4. Orphal, Miriam, Gillespie, Allan, Böhme, Karen, Eisenreich, Andreas, Kreutz, Reinhold. 2020. TMEM63C, a Potential Novel Target for Albuminuria Development, Is Regulated by MicroRNA-564 and Transforming Growth Factor beta in Human Renal Cells. In Kidney & blood pressure research, 45, 850-862. doi:10.1159/000508477. https://pubmed.ncbi.nlm.nih.gov/33080601/