Neurofibromin (NF1)

Neurofibromin is a large, multifunctional tumor suppressor protein encoded by the NF1 gene on chromosome 17. It acts primarily as a GTPase-activating protein (GAP) for Ras, accelerating the inactivation of Ras by facilitating the conversion of Ras-bound GTP to GDP. This central function keeps Ras-mediated cell growth and proliferation in check. Neurofibromin contains several functional domains: a GAP-related domain (GRD) essential for Ras regulation, as well as Sec14 and pleckstrin homology (PH) domains implicated in lipid signaling and membrane interactions. Direct mutations or deletions of NF1 lead to loss of neurofibromin function, resulting in neurofibromatosis type 1—a common inherited cancer predisposition disorder characterized by cutaneous neurofibromas, café-au-lait spots, learning disabilities, and a high risk for malignant tumors such as malignant peripheral nerve sheath tumors (MPNST) and juvenile myelomonocytic leukemia. Neurofibromin is also involved in a broad range of cellular and neurological functions via modulation of multiple signaling pathways, including PI3K/Akt/mTOR, cAMP/PKA, and cytoskeletal regulation pathways. The protein is widely expressed in neurons, Schwann cells, and cells of the central and peripheral nervous system. Pharmacological targeting usually involves downstream effectors (MEK, mTOR), as direct restoration of neurofibromin activity is not yet clinically available. Loss of neurofibromin has pleiotropic and sometimes severe developmental consequences.

Other names

Neurofibromin 1NF1Neurofibromatosis-related protein NF-1neurofibromatosisvon Recklinghausen diseaseWatson diseaseNFNSVRNFWSS

MEK inhibitors block downstream Ras/MAPK pathway signaling, which is hyperactivated in the absence or dysfunction of neurofibromin. mTOR inhibitors reduce cell proliferation and tumor growth by blocking mTOR signaling, which may be upregulated in NF1-mutated cells. Other mechanisms focus on restoring neurofibromin function or targeting compensatory pathways.