mTOR

mTOR (mechanistic target of rapamycin) is a conserved serine/threonine kinase that functions as a central regulator of cell growth, metabolism, protein synthesis, and autophagy by integrating nutrient availability, growth factor signaling, and cellular energy status^[1][2]. Mechanistically, mTOR assembles into two distinct signaling complexes, mTORC1 and mTORC2, which coordinate anabolic and catabolic processes through partially non-overlapping downstream pathways^[2][3][4]. mTORC1 primarily responds to nutrients and growth factors to promote protein synthesis, biomass accumulation, and metabolic reprogramming while suppressing autophagy, thereby controlling cellular growth and metabolic homeostasis^[1][5]. In contrast, mTORC2 regulates cell survival, proliferation, cytoskeletal organization, and metabolism through signaling networks that include AKT, PKC, and SGK family proteins^[2][4]. Dysregulation of mTOR signaling is strongly associated with cancer, metabolic disorders, aging-related pathologies, and immune dysfunction, highlighting its importance in both physiological regulation and disease progression^[1][6]. In experimental systems, genetic or pharmacological manipulation of mTOR complexes has demonstrated distinct and non-redundant functions of mTORC1 and mTORC2 in cellular differentiation, immune-cell maturation, and tissue development^[4][7][8]. Compared with the related isoform complex mTORC1, mTORC2 exhibits unique regulatory roles in cell survival and autophagy-associated signaling, emphasizing the necessity of complex-specific investigation in mechanistic studies^[4]. For experimental applications, rapamycin and related mTOR inhibitors remain widely used tools for dissecting pathway function, although increasing attention has focused on next-generation inhibitors with improved selectivity toward specific mTOR complexes^[9].