Background In patients with diabetic microvascular complications, decreased perfusion or vascular occlusion, caused by reduced vascular diameter, is a common characteristic that will lead to insufficient blood supply. Yet, the regulatory mechanism and effective treatment approach remain elusive. Methods and Results Our initial findings revealed a notable decrease in the expression of human AQP1 in both diabetic human retina samples (49 healthy vs. 54 diabetic samples) and high-glucose-treated human retinal microvascular endothelial cells. Subsequently, our investigations unveiled a reduction in vascular diameter and compromised perfusion within zebrafish embryos subjected to high glucose treatment. Further analysis indicated a significant downregulation of two aquaporins, aqp1a.1 and aqp8a.1, which are highly enriched in ECs and are notably responsive to hyperglycemic conditions. Intriguingly, the loss of function of aqp1a.1 and/or aqp8a.1 resulted in a reduction of intersegmental vessel diameters, effectively mirroring the phenotype observed in the hyperglycemic zebrafish model. The overexpression of aqp1a.1/aqp8a.1 in zebrafish ECs led to notable enlargement of microvascular diameters. Moreover, the reduced vessel diameters resulting from high-glucose treatment were effectively rescued by the overexpression of these aquaporins. Additionally, both aqp1a.1 and apq8a.1 were localized in the intracellular vacuoles in cultured ECs as well as the ECs of sprouting ISVs, and the loss of Aqps caused the reduction of those vacuoles, which was required for lumenization. Notably, while the loss of AQP1 did not impact EC differentiation from human stem cells, it significantly inhibited vascular formation in differentiated ECs. Conclusion EC-enriched aquaporins regulate the diameter of blood vessels through an intracellular vacuole-mediated process under hyperglycemic conditions. These findings collectively suggest that aquaporins expressed in ECs hold significant promise as potential targets for gene therapy aimed at addressing vascular perfusion defects associated with diabetes.

中文翻译：

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内皮液泡膜中富集的水通道蛋白调节高血糖时微血管的直径

背景 对于患有糖尿病微血管并发症的患者来说，由于血管直径减小而引起的灌注减少或血管闭塞是导致血液供应不足的常见特征。然而，监管机制和有效的治疗方法仍然难以捉摸。方法和结果我们的初步研究结果显示，糖尿病人视网膜样本（49 个健康样本与 54 个糖尿病样本）和高糖处理的人视网膜微血管内皮细胞中，人 AQP1 的表达显着下降。随后，我们的研究发现，经过高葡萄糖处理的斑马鱼胚胎中血管直径减小，灌注受损。进一步分析表明，两种水通道蛋白 aqp1a.1 和 aqp8a.1 显着下调，这两种水通道蛋白在 EC 中高度富集，并且对高血糖条件特别敏感。有趣的是，aqp1a.1 和/或 aqp8a.1 功能的丧失导致节间血管直径减小，有效地反映了在高血糖斑马鱼模型中观察到的表型。斑马鱼 EC 中 aqp1a.1/aqp8a.1 的过度表达导致微血管直径显着增大。此外，这些水通道蛋白的过度表达可以有效挽救高葡萄糖治疗导致的血管直径减小。此外，aqp1a.1和apq8a.1都位于培养的EC以及萌芽ISV的EC的细胞内液泡中，并且Aqps的损失导致这些液泡的减少，这是腔化所需的。值得注意的是，虽然 AQP1 的缺失不会影响人类干细胞向 EC 的分化，但它会显着抑制分化 EC 中的血管形成。结论富含EC的水通道蛋白在高血糖条件下通过细胞内液泡介导的过程调节血管直径。这些发现共同表明，EC 中表达的水通道蛋白有望成为旨在解决与糖尿病相关的血管灌注缺陷的基因治疗的潜在靶点。