受体相互作用蛋白激酶 1 (RIPK1) 响应肿瘤坏死因子 (TNF) 和其他细胞因子，协调细胞生存和细胞死亡之间的决定。虽然 RIPK1 的支架功能对于防止 TNF 诱导的细胞凋亡和坏死性凋亡至关重要，但其激酶活性是坏死性凋亡所必需的，并且部分是细胞凋亡所必需的。尽管 TNF 是一种与糖尿病中 β 细胞损失相关的促炎细胞因子，但 TNF 诱导 β 细胞死亡的机制仍不清楚。在这里，我们使用缺乏 RIPK1 的小鼠剖析了 RIPK1 支架与激酶功能对 β 细胞死亡调节的贡献特别是在 β 细胞（Ripk1β-KO 小鼠）或表达激酶死亡版本的 RIPK1（Ripk1D138N 小鼠）中。这些小鼠接受了链脲佐菌素（一种自身免疫性糖尿病模型）的攻击。此外，Ripk1β-KO 小鼠进一步受到高脂肪饮食的挑战以诱导高血糖。为了进行机制研究，胰岛接受了各种杀伤剂和敏化剂。抑制 RIPK1 激酶活性（Ripk1D138N 小鼠）不会影响 1 型糖尿病模型中高血糖的发生和进展。此外，β细胞中RIPK1表达的缺失并不影响基础条件下的正常血糖或糖尿病挑战下的高血糖。在体外，在没有 RIPK1 的情况下，原代胰岛对 TNF 诱导的细胞凋亡和坏死性凋亡不敏感。有趣的是，我们发现胰岛表现出高水平的抗凋亡细胞 FLICE 抑制蛋白 (cFLIP) 和低水平的细胞凋亡 (Caspase-8) 和坏死性凋亡 (RIPK3) 成分。环己酰亚胺治疗导致 cFLIP 水平降低，使原代胰岛对 TNF 诱导的细胞死亡敏感，这种死亡可通过 caspase 抑制完全阻断。与许多其他细胞类型（例如上皮细胞和免疫细胞）不同，RIPK1 不需要生理条件或糖尿病挑战下β细胞的细胞死亡调节。此外，体内和体外证据表明，胰腺β细胞不会发生坏死性凋亡，而主要是响应TNF而发生半胱天冬酶依赖性死亡。最后，我们的结果表明，β 细胞具有独特的 TNF 细胞毒性调节模式，该模式独立于 RIPK1，并且可能高度依赖于 cFLIP。版权所有 © 2024 作者。由 Elsevier GmbH 出版。保留所有权利。

Receptor-interacting protein kinase 1 (RIPK1) orchestrates the decision between cell survival and cell death in response to tumor necrosis factor (TNF) and other cytokines. Whereas the scaffolding function of RIPK1 is crucial to prevent TNF-induced apoptosis and necroptosis, its kinase activity is required for necroptosis and partially for apoptosis. Although TNF is a proinflammatory cytokine associated with β-cell loss in diabetes, the mechanism by which TNF induces β-cell demise remains unclear.Here, we dissected the contribution of RIPK1 scaffold versus kinase functions to β-cell death regulation using mice lacking RIPK1 specifically in β-cells (Ripk1β-KO mice) or expressing a kinase-dead version of RIPK1 (Ripk1D138N mice), respectively. These mice were challenged with streptozotocin, a model of autoimmune diabetes. Moreover, Ripk1β-KO mice were further challenged with a high-fat diet to induce hyperglycemia. For mechanistic studies, pancreatic islets were subjected to various killing and sensitising agents.Inhibition of RIPK1 kinase activity (Ripk1D138N mice) did not affect the onset and progression of hyperglycemia in a type 1 diabetes model. Moreover, the absence of RIPK1 expression in β-cells did not affect normoglycemia under basal conditions or hyperglycemia under diabetic challenges. Ex vivo, primary pancreatic islets are not sensitised to TNF-induced apoptosis and necroptosis in the absence of RIPK1. Intriguingly, we found that pancreatic islets display high levels of the antiapoptotic cellular FLICE-inhibitory protein (cFLIP) and low levels of apoptosis (Caspase-8) and necroptosis (RIPK3) components. Cycloheximide treatment, which led to a reduction in cFLIP levels, rendered primary islets sensitive to TNF-induced cell death which was fully blocked by caspase inhibition.Unlike in many other cell types (e.g., epithelial, and immune), RIPK1 is not required for cell death regulation in β-cells under physiological conditions or diabetic challenges. Moreover, in vivo and in vitro evidence suggest that pancreatic β-cells do not undergo necroptosis but mainly caspase-dependent death in response to TNF. Last, our results show that β-cells have a distinct mode of regulation of TNF-cytotoxicity that is independent of RIPK1 and that may be highly dependent on cFLIP.Copyright © 2024 The Author(s). Published by Elsevier GmbH.. All rights reserved.