Jacovetti Cécile, Jimenez Veronica, Ayuso Eduard, Laybutt Ross, Peyot Marie-Line, Prentki Marc, Bosch Fatima, Regazzi Romano
Department of Fundamental Neurosciences (C.J., R.R.), University of Lausanne, 1005 Lausanne, Switzerland; Center of Animal Biotechnology and Gene Therapy and Department of Biochemistry and Molecular Biology (V.J., E.A., F.B.), School of Veterinary Medicine, Universitat Autònoma de Barcelona, 08193 Bellaterra, Centro de Investigación Biomédica en Red de Diabetes y Enfermedades Metabólicas Asociadas, Barcelona, Spain; Diabetes and Obesity Research Program (R.L.), Garvan Institute of Medical Research, St. Vincent's Hospital, Sydney, 2010 New South Wales, Australia; and Montreal Diabetes Research Center and Centre de Recherche du Centre Hospitalier de l'Université de Montréal (M.-L.P., M.P.), and Departments of Nutrition, Biochemistry and Molecular Medicine, University of Montreal, Quebec, H2X 0A9 Canada.
Mol Endocrinol. 2015 May;29(5):693-702. doi: 10.1210/me.2014-1299. Epub 2015 Mar 9.
The elucidation of the mechanisms directing β-cell mass regeneration and maintenance is of interest, because the deficit of β-cell mass contributes to diabetes onset and progression. We previously found that the level of the microRNA (miRNA) miR-338-3p is decreased in pancreatic islets from rodent models displaying insulin resistance and compensatory β-cell mass expansion, including pregnant rats, diet-induced obese mice, and db/db mice. Transfection of rat islet cells with oligonucleotides that specifically block miR-338-3p activity increased the fraction of proliferating β-cells in vitro and promoted survival under proapoptotic conditions without affecting the capacity of β-cells to release insulin in response to glucose. Here, we evaluated the role of miR-338-3p in vivo by injecting mice with an adeno-associated viral vector permitting specific sequestration of this miRNA in β-cells. We found that the adeno-associated viral construct increased the fraction of proliferating β-cells confirming the data obtained in vitro. miR-338-3p is generated from an intron of the gene coding for apoptosis-associated tyrosine kinase (AATK). Similarly to miR-338-3p, we found that AATK is down-regulated in rat and human islets and INS832/13 β-cells in the presence of the cAMP-raising agents exendin-4, estradiol, and a G-protein-coupled Receptor 30 agonist. Moreover, AATK expression is reduced in islets of insulin resistant animal models and selective silencing of AATK in INS832/13 cells by RNA interference promoted β-cell proliferation. The results point to a coordinated reduction of miR-338-3p and AATK under insulin resistance conditions and provide evidence for a cooperative action of the miRNA and its hosting gene in compensatory β-cell mass expansion.
阐明指导β细胞质量再生和维持的机制备受关注，因为β细胞质量不足会导致糖尿病的发生和发展。我们之前发现，在显示胰岛素抵抗和代偿性β细胞质量扩张的啮齿动物模型（包括妊娠大鼠、饮食诱导肥胖小鼠和db/db小鼠）的胰岛中，微小RNA（miRNA）miR-338-3p的水平降低。用特异性阻断miR-338-3p活性的寡核苷酸转染大鼠胰岛细胞，可增加体外增殖β细胞的比例，并在促凋亡条件下促进细胞存活，而不影响β细胞对葡萄糖刺激释放胰岛素的能力。在此，我们通过向小鼠注射腺相关病毒载体，使该miRNA在β细胞中特异性隔离，从而评估miR-338-3p在体内的作用。我们发现，腺相关病毒构建体增加了增殖β细胞的比例，证实了体外实验获得的数据。miR-338-3p由编码凋亡相关酪氨酸激酶（AATK）的基因内含子产生。与miR-338-3p类似，我们发现，在存在升高cAMP的药物艾塞那肽-4、雌二醇和G蛋白偶联受体30激动剂的情况下，大鼠和人类胰岛以及INS832/13β细胞中的AATK表达下调。此外，在胰岛素抵抗动物模型的胰岛中，AATK表达降低，通过RNA干扰在INS832/13细胞中选择性沉默AATK可促进β细胞增殖。结果表明，在胰岛素抵抗条件下，miR-338-3p和AATK协同下调，并为该miRNA及其宿主基因在代偿性β细胞质量扩张中的协同作用提供了证据。
