TFAP2A orchestrates gene regulatory networks and tubular architecture in kidney outer medullary collecting ducts
Janna Leiz, Karen I. López-Cayuqueo, Shuang Cao, Louisa M.S. Gerhardt, Christian Hinze, Kai M. Schmidt-Ott
Janna Leiz, Karen I. López-Cayuqueo, Shuang Cao, Louisa M.S. Gerhardt, Christian Hinze, Kai M. Schmidt-Ott
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Research Article Cell biology Nephrology

TFAP2A orchestrates gene regulatory networks and tubular architecture in kidney outer medullary collecting ducts

Abstract

Mutations in the transcription factor TFAP2A are linked to congenital anomalies of the kidney and urinary tract in humans. While Tfap2a knockout (KO) in mouse collecting ducts leads to tubular epithelial abnormalities, its precise molecular functions in kidney tubules remain unclear. To investigate Tfap2a-dependent gene regulatory networks in the mouse kidney collecting ducts, we employed conditional KO (Hoxb7-Cre; Tfap2afl/fl) models combined with transcriptomics. Histomorphological and physiological assessments of Tfap2a-KO mice revealed progressive postnatal dilation of the outer medullary collecting ducts. Integrating bulk and single-nucleus RNA sequencing with in silico motif mapping in ATAC-seq datasets demonstrated that Tfap2a is highly expressed and active in normal collecting duct principal cells. Comparative transcriptomics between 3-month-old Tfap2a-KO and control mice identified dysregulated genes associated with cell adhesion and WNT signaling, including Alcam and Wnt9b. These changes were confirmed by in situ hybridization. Our findings reveal that Tfap2a regulates medullary collecting duct diameter by orchestrating a transcriptional network involving Wnt9b and Alcam, providing insights into its role in kidney structural integrity.

Authors

Janna Leiz, Karen I. López-Cayuqueo, Shuang Cao, Louisa M.S. Gerhardt, Christian Hinze, Kai M. Schmidt-Ott

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Figure 2

Transcription factor Tfap2a shows increased regulatory activity in collecting duct principal cells and is associated with pathways related to kidney development.

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Transcription factor Tfap2a shows increased regulatory activity in colle...
(A) Motif enrichment analysis on the differentially accessible regions (DARs) in collecting duct principal cells (CD-PCs). The top 20 motifs with the highest observed frequency are shown (Padj < 0.05). The Tfap2a motif MA0810.1 [TFAP2A(var.2)] is highlighted (red box). Dot size indicates the fold enrichment in comparison to the background dataset. (B) Tfap2a chromVAR motif activity plotted against Tfap2a gene expression. Significant differential chromVAR activity and transcription factor expression (determined by the Seurat FindMarkers function) were observed in the proximal tubule (PT), thick ascending limb (TAL), distal convoluted tubule (DCT), connecting tubule (CNT), collecting duct principal cells (CD-PCs), and interstitial cells (IntCs). (C) Tfap2b chromVAR motif activity plotted against Tfap2b gene expression. Significant differential chromVAR activity and transcription factor expression (determined by the Seurat FindMarkers function) were observed in the PT, TAL, DCT, CNT, CD-PCs, collecting duct intercalated cells (CD-ICs), endothelial cells (ECs), and IntCs. Cell types without significant activity or expression were not included in the plots (B and C). (D) Highly enriched biological processes identified for gene set of 546 genes associated with Tfap2a motif–containing peaks. Colors represent the q value for the depicted process; dot size the number of putative target genes associated with the process. The gene ratio (x axis) represents the number of putative target genes divided by the total number of genes associated with the respective pathway.