Transmembrane protein 127 (TMEM127)

Transmembrane protein 127 (TMEM127) is a highly conserved, multi-pass transmembrane protein identified as a tumor suppressor mutated in familial and sporadic cases of pheochromocytoma and paraganglioma, and rarely in renal cancers[1][2][3][4]. TMEM127 localizes primarily to lysosomal and endosomal membranes where it interacts with the Rag GTPases, the ragulator (LAMTOR) complex, and vATPase—key regulators of amino acid-mediated mTORC1 activation[1][2][3]. Under normal conditions, TMEM127 restrains mTORC1 signaling, impacting cell growth, proliferation, and metabolic homeostasis[1][3][4]. Mutations or loss of TMEM127 result in hyperactivation of mTORC1 and drive tumor formation, establishing it as a central negative regulator in the mTOR pathway[1][3][4]. TMEM127 also modulates nutrient sensing, glucose/insulin homeostasis, immune processes (emerging evidence), and receptor tyrosine kinase signaling (by promoting RET degradation)[2][3]. There are currently no approved drugs targeting TMEM127 directly, but its role in mTOR pathway regulation links it to therapeutic strategies using mTOR inhibitors in cancer[1][4]. TMEM127 gene mutations are a recognized biomarker for adrenal tumor patient selection[4].

mTOR inhibitors act by inhibiting mTOR kinase activity that is dysregulated when TMEM127 is mutated or lost. Drugs modulating lysosomal function or endocytosis may potentially affect TMEM127-related processes (inferred; not directly established).