Men1 Conditional Knockout mouse models

Endocrine tumor suppression centers on Men1, the mouse ortholog of human MEN1, encoding menin, a nuclear scaffold with no intrinsic enzymatic activity that binds the N-terminal fragment of KMT2A and KMT2B to direct H3K4 trimethylation at targets including Cdkn2c and Cdkn1b, while also restraining JUND-dependent transcription and engaging the SMAD3 and beta-catenin axes. Germline heterozygous loss-of-function alleles followed by somatic second hits produce multiple endocrine neoplasia type 1, with parathyroid hyperplasia, gastroenteropancreatic neuroendocrine tumors, and anterior pituitary adenomas, a textbook two-hit mechanism. Homozygous germline deletion is embryonic lethal in midgestation, so heterozygotes supply spontaneous multiendocrine tumor cohorts while conditional nulls driven by Rip-cre, Pdx1-cre, or Gcg-cre restrict loss to beta or alpha cells, shortening latency with clean cell of origin attribution. Because menin also physically gates MLL fusion oncoprotein chromatin occupancy, menin-MLL inhibitor pharmacology is best interrogated with humanized or interface point mutant alleles rather than nulls.

Tissue restricted knockout of Men1 keeps wild type function everywhere else. Breeding is often more robust, and the setup mirrors patient biology where mutations arise in a subset of cells.