Cell Biology & Biophysics Unit, European Molecular Biology Laboratory (EMBL), Heidelberg, Germany.
Department of Chemical Physiology and Biochemistry, Oregon Health & Science University (OHSU), Portland, Oregon, USA.
Physiol Rep. 2022 Jan;10(1):e15159. doi: 10.14814/phy2.15159.
ATP has been previously identified as an autocrine signaling factor that is co-released with insulin to modulate and propagate β-cell activity within islets of Langerhans. Here, we show that β-cell activity and insulin secretion essentially rely on the presence of extracellular ATP. For this, we monitored changes of the intracellular Ca concentration ([Ca ] oscillations) as an immediate read-out for insulin secretion in live cell experiments. Extensive washing of cells or depletion of extracellular ATP levels by recombinant apyrase reduced [Ca ] oscillations and insulin secretion in pancreatic cell lines and primary β-cells. Following ATP depletion, [Ca ] oscillations were stimulated by the replenishment of ATP in a concentration-dependent manner. Inhibition of endogenous ecto-ATP nucleotidases increased extracellular ATP levels, along with [Ca ] oscillations and insulin secretion, indicating that there is a constant supply of ATP to the extracellular space. Our combined results demonstrate that extracellular ATP is essential for β-cell activity. The presented work suggests extracellular ATPases as potential drug targets for the modulation of insulin release. We further found that exogenous fatty acids compensated for depleted extracellular ATP levels by the recovery of [Ca ] oscillations, indicating that autocrine factors mutually compensate for the loss of others. Thereby, our results contribute to a more detailed and complete understanding of the general role of autocrine signaling factors as a fundamental regulatory mechanism of β-cell activity and insulin secretion.
ATP 先前被鉴定为一种自分泌信号因子,与胰岛素一起被共同释放,以调节和传播胰岛内的β细胞活性。在这里,我们表明β细胞活性和胰岛素分泌主要依赖于细胞外 ATP 的存在。为此,我们在活细胞实验中监测细胞内 Ca2+浓度的变化([Ca2+] 振荡),作为胰岛素分泌的直接读出。细胞的广泛洗涤或通过重组 apyrase 耗尽细胞外 ATP 水平会减少胰腺细胞系和原代β细胞中的[Ca2+]振荡和胰岛素分泌。在 ATP 耗尽后,[Ca2+] 振荡通过 ATP 的补充以浓度依赖的方式被刺激。内源性细胞外 ATP 核苷酸酶的抑制增加了细胞外 ATP 水平,以及[Ca2+] 振荡和胰岛素分泌,表明存在持续的 ATP 供应到细胞外空间。我们的综合结果表明细胞外 ATP 对β细胞活性至关重要。所呈现的工作表明细胞外 ATP 酶是调节胰岛素释放的潜在药物靶点。我们还发现,外源性脂肪酸通过恢复[Ca2+]振荡来补偿耗尽的细胞外 ATP 水平,表明自分泌因子相互补偿彼此的损失。因此,我们的结果有助于更详细和完整地理解自分泌信号因子作为β细胞活性和胰岛素分泌的基本调节机制的一般作用。