Tuberous sclerosis complex subunit 1 (TSC1)

Tuberous sclerosis complex subunit 1 (TSC1), also known as hamartin, is a tumor suppressor protein that forms a regulatory complex with TSC2 (tuberin) and TBC1D7. The TSC protein complex acts mainly as a negative regulator of the mechanistic target of rapamycin complex 1 (mTORC1) signaling pathway, which controls cell growth, proliferation, and metabolism. TSC1 serves as a scaffold, stabilizing TSC2 and enabling its GTPase-activating protein (GAP) activity towards Rheb, thereby suppressing mTORC1 signaling. Mutations or loss of function in TSC1 lead to the genetic disease tuberous sclerosis complex, characterized by benign tumors in multiple organ systems and, in some contexts, involvement in cancer pathogenesis[1][2][3]. TSC1 is encoded by the TSC1 gene and produces the hamartin protein[3]. Hamartin (TSC1) interacts directly with tuberin (TSC2); both are essential for the formation and function of the TSC protein complex[1][2]. The TSC complex serves as a central hub in the regulation of cell growth signals, acting upstream of mTORC1[1][2]. Loss of TSC1 function can deregulate mTORC1 activity, leading to abnormal cell growth and the formation of benign tumors called hamartomas, especially in tuberous sclerosis complex[3]. While TSC1 itself is not a direct drug target, the pathway it regulates (the mTORC1 pathway) is targetable, with mTOR inhibitors like sirolimus (rapamycin) and everolimus used to treat TSC-related tumors[1][2]. There are currently no drugs that directly target TSC1; therapies target downstream effectors in the mTOR pathway. Loss of TSC1 function serves as an important biomarker for tuberous sclerosis complex diagnosis and for predicting response to mTOR inhibitors.

Other names

HamartinKIAA0243TSCLAMtuberous sclerosis 1 protein