PHLPP1/2 phosphatases as new target for beta-cell-directed therapy in diabetes

PHLPP1/2 磷酸酶作为 β 细胞定向治疗糖尿病的新靶点

• 批准号: 260745940
• 负责人: Dr. Amin Ardestani, Ph.D.
• 金额: --
• 依托单位: Zentrum für Biomolekulare Interaktionen (CBIB)
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2014
• 资助国家: 德国
• 起止时间: 2013-12-31 至 2021-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/260745940?language=en
• 关键词: PHLPP1; phosphatases; new; target; beta

Both type 1 diabetes (T1D) and type 2 diabetes (T2D) result from a decline in pancreatic beta-cell function and/or mass. There is a critical need to develop therapeutic approaches to restore beta-cell mass in patients with diabetes. Apoptosis as well as impaired function of insulin producing beta-cell are hallmarks of beta-cell failure and the fundamental cause of diabetes. Modulation of beta-cell apoptosis and/or enhancement of regenerative capacity represent an attractive therapeutic approach to the treatment of diabetes. Serine-threonine phosphatases (STPs) such as PHLPP1/2 (PH domain leucine-rich repeat protein phosphatase-1/2) regulate cell death and serve as potential targets for drug development. Our understanding of the function of PHLPPs in beta-cell death regulation has important biological and clinical significance. We show that PHLPP1 and PHLPP2 are highly up-regulated in beta-cells under diabetogenic conditions in vitro, in human T1D and T2D and in mouse models of diabetes. PHLPP1/2 overexpression impairs beta-cell survival and function. PHLPP1/2 induced beta-apoptosis is mediated through the inactivation of AKT pro-survival signaling and the activation of pro-apoptotic MST1 kinase, two well-established PHLPP substrates. During the initial DFG-funded period, we have found: (i) PHLPP, AKT and MST1 form an auto-inhibitory triangle that controls beta-cell apoptosis. (ii) mTORC1 hyper-activation regulates PHLPPs up-regulation, MST1 activation and beta-cell death under diabetic conditions. (iii) Genetic and pharmacological inhibition of PHLPP restores beta-cell survival and insulin secretion in vitro and in in vivo mouse models of diabetes.In the present proposal, we continue to fully discover the mechanism of PHLPP upregulation under diabetic conditions by assessing how PHLPP is upregulated in the -cell and whether mTORC1 controls PHLPPs at the translation level. We will also perform islet transplantation studies; islets from PHLPP1-KO mice and wild-type controls are transplanted into diabetic mice in order to uncover and distinguish an islet specific action and a systemic metabolic benefit of PHLPP1 deletion in vivo. Ultimately, we will investigate the utility, pharmacokinetics and MALDI-based drug localization of specific chemical PHLPP inhibitors available in the lab, and subsequently test their efficacy to restore beta-cell survival and function in vitro and to normalize glycemia, beta-cell survival and function in vivo in a mouse model of diabetes within a preclinical study. The purpose of this application is to further elucidate the cellular and molecular mechanisms of PHLPP regulation and action in pancreatic islets in order to move our initial highly promising results forward into translational research; to establish the previously uncharacterized PHLPP1/2 signaling pathway as a novel target for beta-cell curative pharmacological intervention to restore a functional pancreatic beta-cell mass in diabetes.

1 型糖尿病 (T1D) 和 2 型糖尿病 (T2D) 都是由胰腺 β 细胞功能和/或质量下降引起的。迫切需要开发恢复糖尿病患者β细胞质量的治疗方法。 细胞凋亡以及产生胰岛素的β细胞功能受损是β细胞衰竭的标志，也是糖尿病的根本原因。 β细胞凋亡的调节和/或再生能力的增强代表了治疗糖尿病的有吸引力的治疗方法。丝氨酸-苏氨酸磷酸酶 (STP)，例如 PHLPP1/2（PH 结构域富含亮氨酸重复蛋白磷酸酶-1/2）可调节细胞死亡，并可作为药物开发的潜在靶标。我们对 PHLPPs 在 β 细胞死亡调节中的功能的理解具有重要的生物学和临床意义。我们发现，在体外糖尿病条件下、人类 T1D 和 T2D 以及小鼠糖尿病模型中，PHLPP1 和 PHLPP2 在 β 细胞中高度上调。 PHLPP1/2 过度表达会损害 β 细胞的存活和功能。 PHLPP1/2 诱导的 β 细胞凋亡是通过 AKT 促生存信号传导的失活和促凋亡 MST1 激酶（两种成熟的 PHLPP 底物）的激活来介导的。在 DFG 资助的最初阶段，我们发现：（i）PHLPP、AKT 和 MST1 形成一个控制 β 细胞凋亡的自抑制三角。 (ii) mTORC1 过度激活可调节糖尿病条件下 PHLPPs 上调、MST1 激活和 β 细胞死亡。 (iii) PHLPP 的遗传和药理学抑制可在体外和体内糖尿病小鼠模型中恢复 β 细胞存活和胰岛素分泌。在本提案中，我们通过评估 PHLPP 在  细胞中如何上调以及 mTORC1 是否在翻译水平控制 PHLPP，继续充分发现糖尿病条件下 PHLPP 上调的机制。我们还将进行胰岛移植研究；将来自 PHLPP1-KO 小鼠和野生型对照的胰岛移植到糖尿病小鼠体内，以揭示和区分 PHLPP1 缺失的胰岛特异性作用和体内系统代谢益处。最终，我们将研究实验室中可用的特定化学 PHLPP 抑制剂的效用、药代动力学和基于 MALDI 的药物定位，并随后在临床前研究中测试其在体外恢复 β 细胞存活和功能以及在糖尿病小鼠模型中体内使血糖、β 细胞存活和功能正常化的功效。本申请的目的是进一步阐明 PHLPP 在胰岛中调节和作用的细胞和分子机制，以便将我们最初非常有希望的结果推进到转化研究中；建立以前未表征的 PHLPP1/2 信号通路作为 β 细胞治疗药理学干预的新靶点，以恢复糖尿病患者的功能性胰腺 β 细胞群。

项目成果

Neratinib protects pancreatic beta cells in diabetes

• DOI: 10.1038/s41467-019-12880-5
• 发表时间: 2019-11-01
• 期刊: NATURE COMMUNICATIONS
• 影响因子: 16.6
• 作者: Ardestani, Amin;Li, Sijia;Maedler, Kathrin
• 通讯作者: Maedler, Kathrin

Reciprocal regulation of mTOR complexes in pancreatic islets from humans with type 2 diabetes

• DOI: 10.1007/s00125-016-4188-9
• 发表时间: 2017-04
• 期刊: Diabetologia
• 影响因子: 8.2
• 作者: T. Yuan;Sahar Rafizadeh;K. D. D. Gorrepati-K.-D.-D.-Gorrepati-6370876;Blaz Lupse;J. Oberholzer;K. Maedler;A. Ardestani