Bicarbonate-based peritoneal dialysis (PD) fluids enhance the migratory capacity and damage-repair ability of human peritoneal mesothelial cells by upregulating AQP1. However, little is known about the underlying molecular mechanisms. Here we used HEK-293T cells to investigate the effect of pH on AQP1 gene transcription levels. We found that AQP1 mRNA levels increases with pH. Transfection of HEK-293T cells with luciferase reporter vectors containing different regions of the AQP1 promoter identified an upstream region in the AQP1 gene between − 2200 and – 2300 bp as an enhancer required for pH-mediated regulation of AQP1 expression. Site-directed mutagenesis of this specific promoter region revealed a critical region between − 2257 and − 2251 bp, and gene knock-down experiments and ChIP assays suggested that the Spi-B transcription factor SPIB is involved in pH-mediated regulation of AQP1 expression. We identified an upstream region in the AQP1 gene and the transcription factor SPIB that are critically involved in pH-mediated regulation of AQP1 expression. These findings provide the basis for further studies on the pH- and buffer-dependent effects of PD fluids on peritoneal membrane integrity and function.

中文翻译：

---

pH值通过Spi-B转录因子介导的AQP1基因表达上调。

基于碳酸氢盐的腹膜透析（PD）液通过上调AQP1增强人腹膜间皮细胞的迁移能力和损伤修复能力。但是，对潜在的分子机制知之甚少。在这里，我们使用HEK-293T细胞来研究pH对AQP1基因转录水平的影响。我们发现AQP1 mRNA水平随pH升高而增加。用含有AQP1启动子不同区域的荧光素酶报告载体转染HEK-293T细胞，发现AQP1基因的上游区域介于-2200和-2300 bp之间，是pH介导的调节AQP1表达所需的增强子。此特定启动子区域的定点诱变显示在-2257和-2251 bp之间的关键区域，基因敲除实验和ChIP分析表明，Spi-B转录因子SPIB参与pH介导的AQP1表达调节。我们在AQP1基因和转录因子SPIB中鉴定了一个上游区域，这些区域在pH介导的AQP1表达调节中至关重要。这些发现为进一步研究PD液对腹膜完整性和功能的pH和缓冲液依赖性作用提供了基础。