Kidney intercalated cells and the transcription factor FOXi1 drive cystogenesis in tuberous sclerosis complex.

Abstract

Tuberous sclerosis complex (TSC) is caused by mutations in either TSC1 or TSC2 genes and affects multiple organs, including kidney, lung, and brain. In the kidney, TSC presents with the enlargement of benign tumors (angiomyolipomata) and cysts, which eventually leads to kidney failure. The factors promoting cyst formation and tumor growth in TSC are incompletely understood. Here, we report that mice with principal cell-specific inactivation of Tsc1 develop numerous cortical cysts, which are overwhelmingly composed of hyperproliferating A-intercalated (A-IC) cells. RNA sequencing and confirmatory expression studies demonstrated robust expression of Forkhead Transcription Factor 1 (Foxi1) and its downstream targets, apical H+-ATPase and cytoplasmic carbonic anhydrase 2 (CAII), in cyst epithelia in Tsc1 knockout (KO) mice but not in Pkd1 mutant mice. In addition, the electrogenic 2Cl-/H+ exchanger (CLC-5) is significantly up-regulated and shows remarkable colocalization with H+-ATPase on the apical membrane of cyst epithelia in Tsc1 KO mice. Deletion of Foxi1, which is vital to intercalated cells viability and H+-ATPase expression, completely abrogated the cyst burden in Tsc1 KO mice, as indicated by MRI images and histological analysis in kidneys of Foxi1/Tsc1 double-knockout (dKO) mice. Deletion of CAII, which is critical to H+-ATPase activation, caused significant reduction in cyst burden and increased life expectancy in CAII/Tsc1 dKO mice vs. Tsc1 KO mice. We propose that intercalated cells and their acid/base/electrolyte transport machinery (H+-ATPase/CAII/CLC-5) are critical to cystogenesis, and their inhibition or inactivation is associated with significant protection against cyst generation and/or enlargement in TSC.

• Authors: Sharon Barone, Kamyar Zahedi, Marybeth Brooks, Elizabeth P Henske, Yirong Yang, Erik Zhang, John J Bissler, Jane J Yu, Manoocher Soleimani
• Journal: Proceedings of the National Academy of Sciences of the United States of America (Proc Natl Acad Sci U S A) Vol. 118 Issue 6 (02 09 2021) ISSN: 1091-6490 [Electronic] United States
• PMID: 33536341 (Publication Type: Journal Article, Research Support, N.I.H., Extramural, Research Support, Non-U.S. Gov't, Research Support, U.S. Gov't, Non-P.H.S.)
• Copyright: Copyright © 2021 the Author(s). Published by PNAS.

Chemical References

• Forkhead Transcription Factors
• Foxi1 protein, mouse
• TRPP Cation Channels
• Tsc1 protein, mouse
• Tuberous Sclerosis Complex 1 Protein
• polycystic kidney disease 1 protein
• Proton-Translocating ATPases
• Carbonic Anhydrase II
• CA2 protein, human

Topics

• Animals
• Carbonic Anhydrase II (genetics)
• Cysts (genetics, pathology)
• Disease Models, Animal
• Forkhead Transcription Factors (genetics)
• Humans
• Kidney (metabolism, pathology)
• Mice
• Mutation (genetics)
• Proton-Translocating ATPases (genetics)
• Renal Insufficiency (genetics, pathology)
• TRPP Cation Channels (genetics)
• Tuberous Sclerosis
• Tuberous Sclerosis Complex 1 Protein (genetics)