Menin and TGF-beta superfamily member signaling via the Smad pathway in pituitary, parathyroid and osteoblast.
PITUITARY: Menin is a Smad3-interacting protein; inactivation of menin blocks transforming growth factor (TGF)-beta and activin signaling, antagonizing their growth-inhibitory properties in anterior pituitary cells. Menin is also required for the activin-induced inhibition of prolactin expression mediated by the Smads and the transcription factor, Pit-1. The interaction between menin and Smad3 is direct. PARATHYROID: In cultured parathyroid cells from uremic hemodialysis patients, in which the menin signaling pathways are probably still intact, menin inactivation achieved by menin antisense oligonucleotides leads to loss of TGF-beta inhibition of parathyroid cell proliferation and parathyroid hormone (PTH) secretion. Moreover, TGF-beta does not affect the proliferation and PTH production of parathyroid cells from multiple endocrine neoplasia type 1 (MEN1) patients. OSTEOBLAST: Men1-null mouse fetuses that die at day 12 or earlier have cranial/facial hypoplasias implicating menin in bone development. Menin is required for the commitment of multipotential mesenchymal stem cells into the osteoblast lineage. This is achieved by menin interacting physically and functionally with bone morphogenetic protein (BMP)-2 regulated Smads, such as Smad1 and Smad5, and the key osteoblast regulator, Runx2. These interactions are lost as the committed osteoblasts differentiate further at which time menin interacts with Smad3, mediating the negative regulation of Runx2 by TGF-beta. Menin also suppresses osteoblast maturation, partly by inhibiting the differentiation actions of JunD.
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Department of Medicine, Physiology and Human Genetics, McGill University, and Calcium Research Laboratory and Hormones and Cancer Research Unit, Royal Victoria Hospital, 687 Pine Avenue West, Montreal, Quebec, Canada H3A 1A1. geoffrey.hendy@mcgill.ca
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D000818:Animals; D002454:Cell Differentiation / Q000235:genetics; D002478:Cells, Cultured; D004268:DNA-Binding Proteins / Q000378:metabolism*; D006801:Humans; D051379:Mice; D008817:Mice, Mutant Strains; D018761:Multiple Endocrine Neoplasia Type 1 / Q000235:genetics / Q000378:metabolism; D010006:Osteoblasts / Q000378:metabolism*; D010902:Pituitary Gland / Q000378:metabolism*; D011518:Proto-Oncogene Proteins / Q000235:genetics; D015398:Signal Transduction; D051785:Smad Proteins; D051898:Smad1 Protein; D013961:Thyroid Gland / Q000166:cytology / Q000378:metabolism*; D015534:Trans-Activators / Q000378:metabolism*; D016212:Transforming Growth Factor beta / Q000378:metabolism*
D004268:DNA-Binding Proteins; C484898:Men1 protein, mouse; D011518:Proto-Oncogene Proteins; C497399:SMAD1 protein, human; D051785:Smad Proteins; D051898:Smad1 Protein; C497401:Smad1 protein, mouse; D015534:Trans-Activators; D016212:Transforming Growth Factor beta