Rictor beyond the TORC: linking the proliferation, migration and FcεRI-mediated degranulation of human mast cells

Rictor is a cytosolic protein that was originally recognized as a specific component of the mammalian target of rapamycin (mTOR) complex 2 (mTORC2). This complex integrates nutrient- and growth factor-induced signaling cascades to regulate cell proliferation and metabolism. An increasing body of evidence however shows that rictor may also function independently of mTORC2 through association with other proteins and complexes. Recent studies on mast cells demonstrated that in the context of mTORC2 rictor positively regulates proliferation of immature and migration of mature mast cells whereas by itself rictor independently functions as a molecular relay that sets the sensitivity of high affinity receptor for IgE (FceRI) for activating mast cell degranulation. These novel findings suggest that rictor is a multifunctional protein that plays a role in synchronization of multiple cellular functions in mast cells.