Comprehensive alpha, beta and delta cell transcriptomes reveal that ghrelin selectively activates delta cells and promotes somatostatin release from pancreatic islets.
Comprehensive alpha, beta and delta cell transcriptomes reveal that ghrelin selectively activates delta cells and promotes somatostatin release from pancreatic islets.
复制标题
DOI：
10.1016/j.molmet.2016.04.007
复制
发表时间：
2016-07
影响因子：
8.1
通讯作者：
Huising MO
中科院分区：
文献类型：
--
作者：
DiGruccio MR;Mawla AM;Donaldson CJ;Noguchi GM;Vaughan J;Cowing-Zitron C;van der Meulen T;Huising MO
胰岛内的内分泌细胞之间的复杂局部串扰确保了它们的内分泌输出的紧密协调。最近的研究表明，胰岛内δ细胞的负反馈控制决定了小鼠出生后发育期间血糖的稳态设定点。然而，促进旁分泌串扰的胰岛内分泌细胞的密切联系也使直接介导的β细胞效应与通过局部中间体介导的间接效应之间的区别复杂化，例如来自δ细胞的生长抑素。为了解决这个问题，我们产生了报告小鼠，其允许从相同的胰岛收集纯的胰腺δ细胞沿着α和β细胞，并产生了每种胰岛内分泌细胞类型的综合转录组。这些转录组提供了由δ、α和β细胞表达的受体的无与伦比的视图，并且允许以非常准确的方式预测哪些信号靶向哪些内分泌细胞类型。从这些转录组中，我们发现生长素释放肽受体仅由胰岛内的δ细胞表达，这通过荧光原位杂交和qPCR证实。事实上，生长素释放肽增加完整小鼠胰岛中δ细胞的细胞内钙，通过GCaMP6测量，并且在静态和灌注测定中强烈增强小鼠和人胰岛上葡萄糖刺激的生长抑素分泌。相反，相同剂量的去酰基ghrelin对生长抑素分泌没有影响，也没有阻断ghrelin的作用。这些结果为众所周知的生长激素释放肽的胰岛素抑制作用提供了一个简单的解释。生长激素释放肽不是直接与β细胞结合，而是与δ细胞结合，以促进局部抑制性反馈，从而减弱胰岛素释放。这些发现说明了我们的方法解决一些长期存在的难题的力量，这些难题与胰岛内发生的丰富反馈有关，这些反馈是胰岛生理学不可或缺的，因此与糖尿病高度相关。
Complex local crosstalk amongst endocrine cells within the islet ensures tight coordination of their endocrine output. This is illustrated by the recent demonstration that the negative feedback control by delta cells within pancreatic islets determines the homeostatic set-point for plasma glucose during mouse postnatal development. However, the close association of islet endocrine cells that facilitates paracrine crosstalk also complicates the distinction between effects mediated directly on beta cells from indirect effects mediated via local intermediates, such as somatostatin from delta cells. To resolve this problem, we generated reporter mice that allow collection of pure pancreatic delta cells along with alpha and beta cells from the same islets and generated comprehensive transcriptomes for each islet endocrine cell type. These transcriptomes afford an unparalleled view of the receptors expressed by delta, alpha and beta cells, and allow the prediction of which signal targets which endocrine cell type with great accuracy. From these transcriptomes, we discovered that the ghrelin receptor is expressed exclusively by delta cells within the islet, which was confirmed by fluorescent in situ hybridization and qPCR. Indeed, ghrelin increases intracellular calcium in delta cells in intact mouse islets, measured by GCaMP6 and robustly potentiates glucose-stimulated somatostatin secretion on mouse and human islets in both static and perfusion assays. In contrast, des-acyl-ghrelin at the same dose had no effect on somatostatin secretion and did not block the actions of ghrelin. These results offer a straightforward explanation for the well-known insulinostatic actions of ghrelin. Rather than engaging beta cells directly, ghrelin engages delta cells to promote local inhibitory feedback that attenuates insulin release. These findings illustrate the power of our approach to resolve some of the long-standing conundrums with regard to the rich feedback that occurs within the islet that is integral to islet physiology and therefore highly relevant to diabetes.