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J Am Soc Nephrol. 2015 Nov;26(11):2704-15. doi: 10.1681/ASN.2014080759. Epub 2015 Mar 18.

A Grainyhead-Like 2/Ovo-Like 2 Pathway Regulates Renal Epithelial Barrier Function and Lumen Expansion.

Author information

1
Max Delbrueck Center for Molecular Medicine, Berlin, Germany; Experimental and Clinical Research Center, and.
2
Max Delbrueck Center for Molecular Medicine, Berlin, Germany; Departments of Nephrology.
3
Max Delbrueck Center for Molecular Medicine, Berlin, Germany;
4
Max Delbrueck Center for Molecular Medicine, Berlin, Germany; Urology, Berlin Institute of Urologic Research, Berlin, Germany.
5
Urology, Berlin Institute of Urologic Research, Berlin, Germany.
6
Pathology, and.
7
Gastroenterology, Charité Medical University, Berlin, Germany; and.
8
Max Delbrueck Center for Molecular Medicine, Berlin, Germany; Experimental and Clinical Research Center, and Departments of Nephrology, kai.schmidt-ott@charite.de.

Abstract

Grainyhead transcription factors control epithelial barriers, tissue morphogenesis, and differentiation, but their role in the kidney is poorly understood. Here, we report that nephric duct, ureteric bud, and collecting duct epithelia express high levels of grainyhead-like homolog 2 (Grhl2) and that nephric duct lumen expansion is defective in Grhl2-deficient mice. In collecting duct epithelial cells, Grhl2 inactivation impaired epithelial barrier formation and inhibited lumen expansion. Molecular analyses showed that GRHL2 acts as a transcriptional activator and strongly associates with histone H3 lysine 4 trimethylation. Integrating genome-wide GRHL2 binding as well as H3 lysine 4 trimethylation chromatin immunoprecipitation sequencing and gene expression data allowed us to derive a high-confidence GRHL2 target set. GRHL2 transactivated a group of genes including Ovol2, encoding the ovo-like 2 zinc finger transcription factor, as well as E-cadherin, claudin 4 (Cldn4), and the small GTPase Rab25. Ovol2 induction alone was sufficient to bypass the requirement of Grhl2 for E-cadherin, Cldn4, and Rab25 expression. Re-expression of either Ovol2 or a combination of Cldn4 and Rab25 was sufficient to rescue lumen expansion and barrier formation in Grhl2-deficient collecting duct cells. Hence, we identified a Grhl2/Ovol2 network controlling Cldn4 and Rab25 expression that facilitates lumen expansion and barrier formation in subtypes of renal epithelia.

KEYWORDS:

Grainyhead transcription factors; Grainyhead-like 2; barrier; collecting duct; formation; lumen expansion; nephric duct

PMID:
25788534
PMCID:
PMC4625669
DOI:
10.1681/ASN.2014080759
[Indexed for MEDLINE]
Free PMC Article

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