The nuclear factor of activated T cells 5 (NFAT5) contributes to the renal corticomedullary differences in gene expression

Abstract

The corticomedullary osmotic gradient between renal cortex and medulla induces a specific spatial gene expression pattern. The factors that controls these differences are not fully addressed. Adaptation to hypertonic environment is mediated by the actions of the nuclear factor of activated T-cells 5 (NFAT5). NFAT5 induces the expression of genes that lead to intracellular accumulation of organic osmolytes. However, a systematical analysis of the NFAT5-dependent gene expression in the kidneys was missing. We used primary cultivated inner medullary collecting duct (IMCD) cells from control and NFAT5 deficient mice as well as renal cortex and inner medulla from principal cell specific NFAT5 deficient mice for gene expression profiling. In primary NFAT5 deficient IMCD cells, hyperosmolality induced changes in gene expression were abolished. The majority of the hyperosmolality induced transcripts in primary IMCD culture were determined to have the greatest expression in the inner medulla. Loss of NFAT5 altered the expression of more than 3000 genes in the renal cortex and more than 5000 genes in the inner medulla. Gene enrichment analysis indicated that loss of NFAT5 is associated with renal inflammation and increased expression of kidney injury marker genes, like lipocalin-2 or kidney injury molecule-1. In conclusion we show that NFAT5 is a master regulator of gene expression in the kidney collecting duct and in vivo loss of NFAT function induces a kidney injury like phenotype.

Differences in chromatin accessibility between renal cortex and inner medulla correlate with spatial differences in gene expression and are modulated by NFAT5 function

“…The factors that control these changes are not fully understood. There is plenty of evidence that the unique hypertonic environment in the renal inner medulla mediates a specific gene expression pattern 12, 29, 52 31 . With this study, we provide evidences that the differences in the chromatin accessibility contribute to the observed changes.…”

“…Surprisingly the analysis of TF motifs did not show a significant enrichment of NFAT5 motifs in the IM for DAR regions. Loss of NFAT5 in the induced a diabetes insipidus like phenotype and this was associated with massive changes in gene expression 29, 32 . The changes in gene expression are also associated with differences in chromatin accessibility.…”

“…Several studies using cell lines and native tissue have shown, that hypertonicity and NFAT5 are master regulators of Aqp2 expression 29, 32, 52, 65 . Here we showed that the increased Aqp2 expression in the IM is associated with a gain of accessibility of Aqp2 at the promotor region.…”

“…The loss of NFAT5 is linked to renal inflammation and an up-regulation of kidney injury marker genes 29 . The underlying mechanism for this increased expression of immune-related genes is likely due to an increased infiltration of immune cells, indicated by the elevated expression of Cd4 , Cd8, or Cd14 29 . Higher gene expression depends on the condition of enhanced accessibility of these genes.…”

“…Additionally, NFAT5 is implicated in the regulation of urea transporters 26 and the water channel aquaporin-2 (AQP2) 27 , These genes were also found to have hypertonicity-induced increase of gene expression 28,29 . Despite the established role of NFAT5 in response to hypertonicity, its functions independent of hypertonic challenge and its comprehensive impact on renal gene expression profiles remain poorly understood.…”