Beta cell Notch activity in Type 2 Diabetes

项目摘要 β细胞质量和功能适应机体对胰岛素的需求，以在整个生命周期内维持正常血糖 广泛的病理生理学，如肥胖、怀孕或衰老引起的胰岛素抵抗。虽然 使β细胞适应这些应激源的分子机制还没有完全了解，还不够充分 随着2型糖尿病(T2D)的发作，功能适应在临床上变得明显。随着持续的 肥胖增加，寻求调节β细胞适应的新的治疗易处理的途径 逆转T2D的β细胞功能障碍。 Noch是一个高度保守的蛋白质家族，对细胞命运的决定至关重要；在发育中的内分泌中 胰腺，Notch信号调节β细胞分化，但对Notch在成熟细胞中的作用知之甚少 组织。我们最近发现，Notch信号在完全发育的β细胞中存在于低水平，但 在高糖培养的胰岛或肥胖小鼠分离的胰岛中增加。持续的β信元陷阱信令 似乎对功能有害，因为我们观察到β细胞的遗传抑制改善了葡萄糖耐量 开槽动作。相反，强制激活Notch会损害葡萄糖刺激的胰岛素分泌(GSIS) 分离小鼠或人的胰岛，并诱导β细胞特异性Notch功能增益小鼠的葡萄糖耐量增加。 在目标1中，我们利用显示β细胞缺口增加的数据来研究β细胞缺口活性增加的机制 Notch配体Jagged1的表达与Notch活性密切相关。我们测试β细胞Jagged1是否 肥胖症中非适应性β细胞切迹反应的充要条件。在目标2中，我们解决了 缺口诱发GSIS缺陷的机理。在关键的初步数据中，我们发现Notch会导致降解 β细胞成熟度的关键调控因子MafA的表达在T2D中被干扰。我们还观察到新的Mafa乙酰化，被阻止 按凹槽活动。我们现在研究Mafa的稳定性和活性是否依赖于乙酰化，并阐明 这些翻译后修饰背后的分子机制。我们还测试了Notch是否会影响 密切相关的转录因子MafB的稳定性和乙酰化。最后，在目标3中，我们测试其含义 我们已确定的Noch-MAFA/B轴在人β细胞对葡萄糖的转录和功能反应中的作用 AS对人胰岛β细胞异质性的影响。实现此应用程序的目标将决定 Notch激活的上游信号，Notch诱导的β细胞功能障碍的下游效应因子，以及 有可能为T2D患者的护理开发新的治疗方向。

Project Abstract β cell mass and function adapts to the insulin requirements of the organism to maintain euglycemia across a wide range of pathophysiology, such as insulin resistance induced by obesity, pregnancy or aging. Although molecular mechanisms that enable β cell adaptation to these stressors are not yet fully understood, insufficient functional adaptation becomes clinically apparent with the onset of Type 2 Diabetes (T2D). With the continued increase in obesity, novel therapeutically-tractable pathways that regulate β cell adaptation are sought to reverse β cell dysfunction in T2D. Notch is a highly conserved family of proteins critical for cell fate decision-making; in the developing endocrine pancreas, Notch signaling regulates β cell differentiation, but less is known about Notch action in mature tissue. We have recently shown that Notch signaling is present at low levels in fully developed β cells, but increased in islets cultured in high glucose or isolated from obese mice. Persistent β cell Notch signaling appears detrimental to function, as we observed improved glucose tolerance with genetic inhibition of β cell Notch action. Conversely, forced Notch activation impaired glucose-stimulated insulin secretion (GSIS) in isolated mouse or human islets, and induced glucose intolerance in β cell-specific Notch gain-of-function mice. In Aim 1, we investigate mechanism of increased β cell Notch activity, leveraging data showing that β cell expression of the Notch ligand, Jagged1, tracks with Notch activity. We test whether β cell Jagged1 is necessary and sufficient for the maladaptive β cell Notch response in obesity. In Aim 2, we address mechanism of Notch-induced GSIS defects. In key preliminary data, we found that Notch induces degradation of MafA, a key regulator of β cell maturity disrupted in T2D. We also observe novel MafA acetylations, blocked by Notch activity. We now study whether MafA stability and activity is dependent on acetylations, and elucidate the molecular machinery underlying these post-translational modifications. We also test whether Notch impacts stability and acetylation of the closely related transcription factor, MafB. Finally, in Aim 3, we test implications of our identified NOTCH-MAFA/B axis in human β cell transcriptional and function response to glucose, as well as effects on β cell heterogeneity in human islets. Achieving the goals of this application will determine upstream signals for Notch activation, downstream effectors of Notch-induced β cell dysfunction, and potentially develop novel therapeutic directions for the care of patients with T2D.