| First Author | Chen H | Year | 2009 |
| Journal | Genes Dev | Volume | 23 |
| Issue | 8 | Pages | 975-85 |
| PubMed ID | 19390090 | Mgi Jnum | J:147942 |
| Mgi Id | MGI:3843078 | Doi | 10.1101/gad.1742509 |
| Citation | Chen H, et al. (2009) Polycomb protein Ezh2 regulates pancreatic beta-cell Ink4a/Arf expression and regeneration in diabetes mellitus. Genes Dev 23(8):975-85 |
| abstractText | Proliferation of pancreatic islet beta cells is an important mechanism for self-renewal and for adaptive islet expansion. Increased expression of the Ink4a/Arf locus, which encodes the cyclin-dependent kinase inhibitor p16(INK4a) and tumor suppressor p19(Arf), limits beta-cell regeneration in aging mice, but the basis of beta-cell Ink4a/Arf regulation is poorly understood. Here we show that Enhancer of zeste homolog 2 (Ezh2), a histone methyltransferase and component of a Polycomb group (PcG) protein complex, represses Ink4a/Arf in islet beta cells. Ezh2 levels decline in aging islet beta cells, and this attrition coincides with reduced histone H3 trimethylation at Ink4a/Arf, and increased levels of p16(INK4a) and p19(Arf). Conditional deletion of beta-cell Ezh2 in juvenile mice also reduced H3 trimethylation at the Ink4a/Arf locus, leading to precocious increases of p16(INK4a) and p19(Arf). These mutant mice had reduced beta-cell proliferation and mass, hypoinsulinemia, and mild diabetes, phenotypes rescued by germline deletion of Ink4a/Arf. beta-Cell destruction with streptozotocin in controls led to increased Ezh2 expression that accompanied adaptive beta-cell proliferation and re-establishment of beta-cell mass; in contrast, mutant mice treated similarly failed to regenerate beta cells, resulting in lethal diabetes. Our discovery of Ezh2-dependent beta-cell proliferation revealed unique epigenetic mechanisms underlying normal beta-cell expansion and beta-cell regenerative failure in diabetes pathogenesis. |
