Menin

Class

Covalent menin inhibitor (beta-cell regeneration)

Menin is a scaffold protein encoded by the MEN1 gene. It does not act as an enzyme itself but organizes a multiprotein complex built around the histone methyltransferase KMT2A (also called MLL1), which places activating marks on chromatin to switch on specific genes. This menin–KMT2A complex has two disease-relevant roles. In certain leukemias, particularly those with KMT2A gene rearrangements or NPM1 mutations, the complex is hijacked to keep a self-renewal gene program (including HOXA9 and MEIS1) switched on, blocking normal blood cell maturation and sustaining leukemic stem cells. Blocking the menin–KMT2A interaction shuts this program off and allows the abnormal cells to differentiate. Separately, in pancreatic beta cells, menin normally restrains cell division by keeping certain cell-cycle inhibitor genes active. Inhibiting menin in this context can release that brake and promote beta-cell proliferation, a strategy being explored to regenerate insulin-producing tissue in diabetes. Small-molecule menin inhibitors, including covalent ones that bind more durably, are designed to disrupt the menin–KMT2A interface, with the specific therapeutic effect depending on the tissue and disease context in which the pathway is engaged.