Tuberous sclerosis complex 2 (TSC2) (TSC2)

Tuberous sclerosis complex 2 (TSC2), also known as tuberin, is a critical tumor suppressor protein that forms a functional complex with TSC1 (hamartin) and TBC1D7 to regulate the mechanistic target of rapamycin complex 1 (mTORC1) signaling pathway. TSC2 functions as a GTPase-activating protein (GAP) for Rheb, a direct activator of mTORC1; by stimulating the hydrolysis of Rheb-GTP to Rheb-GDP, TSC2 effectively keeps mTORC1 in an inactive state under conditions of low nutrients or energy stress. Loss-of-function mutations in the TSC2 gene lead to constitutive hyperactivation of mTORC1, resulting in uncontrolled cell growth, proliferation, and the development of benign tumors (hamartomas) across multiple organ systems, including the brain, kidneys, heart, and lungs. In clinical practice, TSC2 is the primary driver of Tuberous Sclerosis Complex (TSC) and Lymphangioleiomyomatosis (LAM). While there are currently no approved drugs that directly bind and restore TSC2 function, the pathway is therapeutically targeted using mTOR inhibitors such as everolimus and sirolimus, which provide a downstream bypass to suppress the overactive signaling caused by TSC2 deficiency. These treatments have proven effective in shrinking TSC-related tumors and managing associated symptoms like epilepsy, although they require long-term administration as their effects are often reversible. Emerging research is also exploring gene therapy approaches to restore functional tuberin expression in affected tissues.

Other names

TuberinTSC complex subunit 2Protein phosphatase 1 regulatory subunit 160PPP1R160TSC4LAMTuberous sclerosis 2 protein

TSC2 acts as a GTPase-activating protein (GAP) for the small GTPase Rheb, converting it from an active GTP-bound state to an inactive GDP-bound state, thereby inhibiting the mTORC1 pathway. Therapeutic strategies primarily involve the use of mTOR inhibitors (e.g., Everolimus, Sirolimus) to pharmacologically compensate for the loss of TSC2-mediated inhibition of mTORC1 in patients with TSC2 mutations.