Department of Pediatrics and.
Departments of Medicine and Physiology, University of California, San Francisco, San Francisco, California, USA.
JCI Insight. 2021 Jun 8;6(11):e147699. doi: 10.1172/jci.insight.147699.
SLC26A6 (also known as putative anion transporter 1 [PAT1]) is a Cl-/HCO3- exchanger expressed at the luminal membrane of enterocytes where it facilitates intestinal Cl- and fluid absorption. Here, high-throughput screening of 50,000 synthetic small molecules in cells expressing PAT1 and a halide-sensing fluorescent protein identified several classes of inhibitors. The most potent compound, the pyrazolo-pyrido-pyrimidinone PAT1inh-B01, fully inhibited PAT1-mediated anion exchange (IC50 ~350 nM), without inhibition of the related intestinal transporter SLC26A3 (also known as DRA). In closed midjejunal loops in mice, PAT1inh-B01 inhibited fluid absorption by 50%, which increased to >90% when coadministered with DRA inhibitor DRAinh-A270. In ileal loops, PAT1inh-B01 blocked fluid absorption by >80%, whereas DRAinh-A270 was without effect. In colonic loops, PAT1inh-B01 was without effect, whereas DRAinh-A270 completely blocked fluid absorption. In a loperamide constipation model, coadministration of PAT1inh-B01 with DRAinh-A270 increased stool output compared with DRAinh-A270 alone. These results provide functional evidence for complementary and region-specific roles of PAT1 and DRA in intestinal fluid absorption, with PAT1 as the predominant anion exchanger in mouse ileum. We believe that PAT1inh-B01 is a novel tool to study intestinal ion and fluid transport and perhaps a drug candidate for small intestinal hyposecretory disorders such as cystic fibrosis-related meconium ileus and distal intestinal obstruction syndrome.
SLC26A6（也称为假定阴离子转运体 1 [PAT1]）是一种在肠上皮细胞的腔膜上表达的 Cl--HCO3-交换器，它促进肠道 Cl-和液体吸收。在这里，在表达 PAT1 和卤化物感应荧光蛋白的细胞中对 50,000 种合成小分子进行高通量筛选，鉴定出几类抑制剂。最有效的化合物是吡唑并吡啶嘧啶酮 PAT1inh-B01，它完全抑制了 PAT1 介导的阴离子交换（IC50~350 nM），而不抑制相关的肠道转运体 SLC26A3（也称为 DRA）。在小鼠的闭合中肠环中，PAT1inh-B01 抑制了 50%的液体吸收，当与 DRA 抑制剂 DRAinh-A270 共同给药时，增加到>90%。在回肠环中，PAT1inh-B01 阻断了>80%的液体吸收，而 DRAinh-A270 则没有效果。在结肠环中，PAT1inh-B01 没有效果，而 DRAinh-A270 则完全阻断了液体吸收。在洛哌丁胺便秘模型中，与 DRAinh-A270 共同给药 PAT1inh-B01 与单独使用 DRAinh-A270 相比增加了粪便排出量。这些结果为 PAT1 和 DRA 在肠道液体吸收中的互补和区域特异性作用提供了功能证据，PAT1 是小鼠回肠中主要的阴离子交换器。我们相信，PAT1inh-B01 是研究肠道离子和液体转运的一种新工具，也许是囊性纤维化相关胎粪性肠梗阻和远端肠梗阻综合征等小肠低分泌性疾病的候选药物。
