Hauke S, Dutta A K, Eisenbeis V B, Bezold D, Bittner T, Wittwer C, Thakor D, Pavlovic I, Schultz C, Jessen H J
EMBL, Heidelberg , 69117 Heidelberg , Germany . Email:
University of Freiburg , Institute of Organic Chemistry , 79104 Freiburg , Germany . Email:
Chem Sci. 2019 Jan 10;10(9):2687-2692. doi: 10.1039/c8sc03479f. eCollection 2019 Mar 7.
Among many cellular functions, inositol pyrophosphates (PP-InsPs) are metabolic messengers involved in the regulation of glucose uptake, insulin sensitivity, and weight gain. However, their mechanisms of action are still poorly understood. So far, the influence of PP-InsPs on cellular metabolism has been studied by overexpression or knockout/inhibition of relevant metabolizing kinases (IP6Ks, PPIP5Ks). These approaches are, , limited by time-resolution and potential compensation mechanisms. Here, we describe the synthesis of cell-permeant caged PP-InsPs as tools to rapidly modulate intracellular levels of defined isomers of PP-InsPs in a genetically non-perturbed cellular environment. We show that caged prometabolites readily enter live cells where they are enzymatically converted into still inactive, metabolically stable, photocaged PP-InsPs. Upon light-triggered release of 5-PP-InsP, the major cellular inositol pyrophosphate, oscillations of intracellular Ca levels in MIN6 cells were transiently reduced to spontaneously recover again. In contrast, uncaging of 1-PP-InsP, a minor cellular isomer, was without effect. These results provide evidence that PP-InsPs play an active role in regulating [Ca] oscillations, a key element in triggering exocytosis and secretion in β-cells.
在众多细胞功能中，肌醇焦磷酸（PP-InsPs）是参与调节葡萄糖摄取、胰岛素敏感性和体重增加的代谢信使。然而，它们的作用机制仍知之甚少。到目前为止，PP-InsPs对细胞代谢的影响已通过相关代谢激酶（IP6Ks、PPIP5Ks）的过表达或敲除/抑制进行了研究。然而，这些方法受到时间分辨率和潜在补偿机制的限制。在这里，我们描述了细胞渗透性笼形PP-InsPs的合成，作为在基因未受干扰的细胞环境中快速调节特定PP-InsP异构体细胞内水平的工具。我们表明，笼形前体代谢物很容易进入活细胞，在那里它们被酶转化为仍然无活性、代谢稳定的光笼形PP-InsPs。在光触发释放主要的细胞肌醇焦磷酸5-PP-InsP后，MIN6细胞内Ca水平的振荡短暂降低，随后又自发恢复。相比之下，释放次要的细胞异构体1-PP-InsP则没有效果。这些结果证明，PP-InsPs在调节[Ca]振荡中发挥积极作用，[Ca]振荡是触发β细胞胞吐作用和分泌的关键因素。
