Division of Endocrinology, the University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA.
Diabetes. 2010 Aug;59(8):1926-36. doi: 10.2337/db09-1776.
Most knowledge on human beta-cell cycle control derives from immunoblots of whole human islets, mixtures of beta-cells and non-beta-cells. We explored the presence, subcellular localization, and function of five early G1/S phase molecules-cyclins D1-3 and cdk 4 and 6-in the adult human beta-cell.
Immunocytochemistry for the five molecules and their relative abilities to drive human beta-cell replication were examined. Human beta-cell replication, cell death, and islet function in vivo were studied in the diabetic NOD-SCID mouse.
Human beta-cells contain easily detectable cdks 4 and 6 and cyclin D3 but variable cyclin D1. Cyclin D2 was only marginally detectable. All five were principally cytoplasmic, not nuclear. Overexpression of the five, alone or in combination, led to variable increases in human beta-cell replication, with the cdk6/cyclin D3 combination being the most robust (15% versus 0.3% in control beta-cells). A single molecule, cdk6, proved to be capable of driving human beta-cell replication in vitro and enhancing human islet engraftment/proliferation in vivo, superior to normal islets and as effectively as the combination of cdk6 plus a D-cyclin.
Human beta-cells contain abundant cdk4, cdk6, and cyclin D3, but variable amounts of cyclin D1. In contrast to rodent beta-cells, they contain little or no detectable cyclin D2. They are primarily cytoplasmic and likely ineffective in basal beta-cell replication. Unexpectedly, cyclin D3 and cdk6 overexpression drives human beta-cell replication most effectively. Most importantly, a single molecule, cdk6, supports robust human beta-cell proliferation and function in vivo.
关于人类β细胞周期控制的大多数知识来源于整个胰岛的免疫印迹，这是β细胞和非β细胞的混合物。我们探索了五种早期 G1/S 期分子（细胞周期蛋白 D1-3 和 CDK4 和 6）在成人β细胞中的存在、亚细胞定位和功能。
检测了这五种分子及其相对驱动人类β细胞复制的能力的免疫细胞化学。研究了体内糖尿病 NOD-SCID 小鼠中的人类β细胞复制、细胞死亡和胰岛功能。
人类β细胞含有可检测到的 CDK4 和 6 和细胞周期蛋白 D3，但细胞周期蛋白 D1 可变。细胞周期蛋白 D2 仅略有检测到。所有这五种物质主要是细胞质的，而不是核的。单独或组合过表达这五种物质，导致人类β细胞复制的可变增加，其中 CDK6/细胞周期蛋白 D3 组合最为有效（15%比对照β细胞中的 0.3%）。单个分子 CDK6 被证明能够在体外驱动人类β细胞复制，并增强体内人胰岛的植入/增殖，优于正常胰岛，与 CDK6 加 D 型细胞周期蛋白的组合一样有效。
人类β细胞含有丰富的 CDK4、CDK6 和细胞周期蛋白 D3，但细胞周期蛋白 D1 的含量可变。与啮齿动物β细胞不同，它们几乎检测不到或检测不到细胞周期蛋白 D2。它们主要是细胞质的，在基础β细胞复制中可能无效。出乎意料的是，细胞周期蛋白 D3 和 CDK6 的过表达最有效地驱动人类β细胞复制。最重要的是，单个分子 CDK6 支持体内强大的人类β细胞增殖和功能。
