SLC26A6-selective inhibitor identified in a small-molecule screen blocks fluid absorption in small intestine.

Abstract

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.

• Authors: Onur Cil, Peter M Haggie, Joseph-Anthony Tapia Tan, Amber A Rivera, Alan S Verkman
• Journal: JCI insight (JCI Insight) Vol. 6 Issue 11 (06 08 2021) ISSN: 2379-3708 [Electronic] United States
• PMID: 34100381 (Publication Type: Journal Article, Research Support, N.I.H., Extramural, Research Support, Non-U.S. Gov't)

Chemical References

• Antidiarrheals
• Antiporters
• Dopamine Plasma Membrane Transport Proteins
• Slc26a6 protein, mouse
• Small Molecule Libraries
• Sulfate Transporters
• Loperamide

Topics

• Animals
• Antidiarrheals (pharmacology)
• Antiporters (antagonists & inhibitors, metabolism)
• Colon (drug effects, metabolism)
• Constipation (chemically induced, metabolism)
• Dopamine Plasma Membrane Transport Proteins (drug effects)
• Drug Evaluation, Preclinical
• HEK293 Cells
• Humans
• Ileum (drug effects, metabolism)
• Intestinal Absorption (drug effects)
• Intestine, Small (drug effects, metabolism)
• Jejunum (drug effects, metabolism)
• Loperamide (pharmacology)
• Mice
• Small Molecule Libraries
• Sulfate Transporters (antagonists & inhibitors, metabolism)