AIMS/HYPOTHESIS ZBED6 (zinc finger, BED-type containing 6) is known to regulate muscle mass by suppression of Igf2 gene transcription. In insulin-producing cell lines, ZBED6 maintains proliferative capacity at the expense of differentiation and beta cell function. The aim was to study the impact of Zbed6 knockout on beta cell function and glucose tolerance in C57BL/6 mice. METHODS Beta cell area and proliferation were determined in Zbed6 knockout mice using immunohistochemical analysis. Muscle and fat distribution were assessed using micro-computed tomography. Islet gene expression was assessed by RNA sequencing. Effects of a high-fat diet were analysed by glucose tolerance and insulin tolerance tests. ZBED6 was overexpressed in EndoC-βH1 cells and human islet cells using an adenoviral vector. Beta cell cell-cycle analysis, insulin release and mitochondrial function were studied in vitro using propidium iodide staining and flow cytometry, ELISA, the Seahorse technique, and the fluorescent probes JC-1 and MitoSox. RESULTS Islets from Zbed6 knockout mice showed lowered expression of the cell cycle gene Pttg1, decreased beta cell proliferation and decreased beta cell area, which occurred independently from ZBED6 effects on Igf2 gene expression. Zbed6 knockout mice, but not wild-type mice, developed glucose intolerance when given a high-fat diet. The high-fat diet Zbed6 knockout islets displayed upregulated expression of oxidative phosphorylation genes and genes associated with beta cell differentiation. In vitro, ZBED6 overexpression resulted in increased EndoC-βH1 cell proliferation and a reduced glucose-stimulated insulin release in human islets. ZBED6 also reduced mitochondrial JC-1 J-aggregate formation, mitochondrial oxygen consumption rates (OCR) and mitochondrial reactive oxygen species (ROS) production, both at basal and palmitate + high glucose-stimulated conditions. ZBED6-induced inhibition of OCR was not rescued by IGF2 addition. ZBED6 reduced levels of the mitochondrial regulator PPAR-γ related coactivator 1 protein (PRC) and bound its promoter/enhancer region. Knockdown of PRC resulted in a lowered OCR. CONCLUSIONS/INTERPRETATION It is concluded that ZBED6 is required for normal beta cell replication and also limits excessive beta cell mitochondrial activation in response to an increased functional demand. ZBED6 may act, at least in part, by restricting PRC-mediated mitochondrial activation/ROS production, which may lead to protection against beta cell dysfunction and glucose intolerance in vivo.

中文翻译：

---

ZBED6 通过维持 β 细胞面积和减少线粒体过度活化来抵消高脂饮食诱导的葡萄糖耐受不良。

目的/假设 ZBED6（锌指，含有 6 的 BED 型）已知通过抑制 Igf2 基因转录来调节肌肉质量。在产生胰岛素的细胞系中，ZBED6 以牺牲分化和 β 细胞功能为代价来维持增殖能力。目的是研究 Zbed6 敲除对 C57BL/6 小鼠 β 细胞功能和葡萄糖耐量的影响。方法 使用免疫组织化学分析测定 Zbed6 基因敲除小鼠的 β 细胞面积和增殖情况。使用微型计算机断层扫描评估肌肉和脂肪分布。通过 RNA 测序评估胰岛基因表达。通过葡萄糖耐量和胰岛素耐量试验分析高脂肪饮食的影响。ZBED6 使用腺病毒载体在 EndoC-βH1 细胞和人胰岛细胞中过表达。β细胞细胞周期分析，使用碘化丙啶染色和流式细胞术、ELISA、Seahorse 技术以及荧光探针 JC-1 和 MitoSox 在体外研究胰岛素释放和线粒体功能。结果 Zbed6基因敲除小鼠的胰岛细胞周期基因Pttg1表达降低，β细胞增殖减少，β细胞面积减少，这与ZBED6对Igf2基因表达的影响无关。Zbed6 基因敲除小鼠，但不是野生型小鼠，在给予高脂肪饮食时会出现葡萄糖不耐受。高脂肪饮食 Zbed6 敲除胰岛显示出上调的氧化磷酸化基因和与 β 细胞分化相关的基因的表达。在体外，ZBED6 过表达导致人类胰岛中 EndoC-βH1 细胞增殖增加和葡萄糖刺激的胰岛素释放减少。ZBED6 还降低了线粒体 JC-1 J 聚集体的形成、线粒体耗氧率 (OCR) 和线粒体活性氧 (ROS) 的产生，无论是在基础和棕榈酸酯 + 高葡萄糖刺激的条件下。ZBED6 诱导的 OCR 抑制并没有通过添加 IGF2 来挽救。ZBED6 降低了线粒体调节因子 PPAR-γ 相关的辅激活因子 1 蛋白 (PRC) 的水平，并结合了其启动子/增强子区域。击倒PRC导致OCR降低。结论/解释 结论是 ZBED6 是正常 β 细胞复制所必需的，并且还限制了响应增加的功能需求的过度 β 细胞线粒体激活。ZBED6 可能至少部分地通过限制 PRC 介导的线粒体激活/ROS 产生来起作用，