TMEM127, a transmembrane protein-encoding gene, functions as a tumor suppressor. It is involved in multiple biological processes, such as being part of the mTORC1 lysosomal nutrient-sensing complex, regulating insulin sensitivity, and participating in receptor tyrosine kinase (RTK) trafficking [6,3,2]. Its dysfunction is associated with diseases like pheochromocytoma and paraganglioma [1,2,4,5,7].

In TMEM127-mutant pheochromocytomas, human cells, and mouse knockout models, there is an accumulation of RET and increased RET signaling due to TMEM127's role in RET cellular positioning, trafficking, and lysosome-mediated degradation [2]. Whole-body Tmem127 knockout mice show decreased adiposity and maintain insulin sensitivity, low hepatic fat deposition, and peripheral glucose clearance after a high-fat diet. Liver-specific and adipose-specific Tmem127 deletion also reveals tissue-specific effects on insulin-related metabolism [3]. Loss of TMEM127 in cell models causes wild-type RET protein accumulation on the cell surface, driving cell proliferation, and also leads to global defects in surface protein activity and function [4].

In conclusion, TMEM127 plays essential roles in tumor suppression, insulin sensitivity regulation, and membrane protein trafficking. Studies using knockout mouse models have been crucial in revealing its role in pheochromocytoma development and metabolic regulation, providing insights into the underlying disease mechanisms and potential therapeutic targets.