Short title: Hnf4a in proximal tubule developmentWord count for abstract: 235 words Word count for text: 3387 wordsThe authors declare no conflict of interest.
ABSTRACTBackground Hnf4a is a major regulator of renal proximal tubule (PT) development. In humans, a mutation in HNF4A is associated with Fanconi renotubular syndrome (FRTS), which is caused by defective PT functions. In mice, mosaic deletion of Hnf4a in the developing kidney causes a paucity of PT cells, leading to FRTS-like symptoms.The molecular mechanisms underlying the role of Hnf4a in PT development remain unclear.
MethodsWe generated a new Hnf4a mutant mouse model employing Osr2Cre, which effectively deletes Hnf4a in developing nephrons. We characterized the mutant phenotype by immunofluorescence analysis. We performed lineage analysis to test if Cdh6+ cells are PT progenitors. We also performed genome-wide mapping of Hnf4a binding sites and differential gene analysis of Hnf4a mutant kidneys to identify direct target genes of Hnf4a.Results Deletion of Hnf4a with Osr2Cre led to complete loss of mature PT cells, causing lethality in the Hnf4a mutant mice. We found that Cdh6 high , LTL low cells serve as PT progenitors and that they show higher proliferation than Cdh6 low , LTL high differentiated PT cells. We also found that Hnf4a is required for PT progenitors to develop into differentiated PT cells. Our genomic analyses revealed that Hnf4a directly regulates the expression of genes involved in transmembrane transport and metabolism.