Glucocorticoid Receptor Maintains Vasopressin Responses in Kidney Collecting Duct Cells

Abstract

Water permeability of the kidney collecting ducts is regulated in part by the amount of the molecular water channel protein aquaporin-2 (AQP2), whose expression, in turn, is regulated by the pituitary peptide hormone vasopressin. We previously showed that stable glucocorticoid receptor knockdown diminished the vasopressin-induced Aqp2 gene expression in the collecting duct cell model mpkCCD. Here, we investigated the pathways regulated by the glucocorticoid receptor by comparing transcriptomes of the mpkCCD cells with or without stable glucocorticoid receptor knockdown. Glucocorticoid receptor knockdown downregulated 5,394 transcripts associated with 55 KEGG pathways including “vasopressin-regulated water reabsorption,” indicative of positive regulatory roles of these pathways in the vasopressin-induced Aqp2 gene expression. Quantitative RT-PCR confirmed the downregulation of the vasopressin V2 receptor transcript upon glucocorticoid receptor knockdown. Glucocorticoid receptor knockdown upregulated 3,785 transcripts associated with 42 KEGG pathways including the “TNF signaling pathway” and “TGFβ signaling pathway,” suggesting the negative regulatory roles of these pathways in the vasopressin-induced Aqp2 gene expression. Quantitative RT-PCR confirmed the upregulation of TNF and TGFβ receptor transcripts upon glucocorticoid receptor knockdown. TNF or TGFβ inhibitor alone, in the absence of vasopressin, did not induce Aqp2 gene transcription. However, TNF or TGFβ blunted the vasopressin-induced Aqp2 gene expression. In particular, TGFβ reduced vasopressin-induced increases in Akt phosphorylation without inducing epithelial-to-mesenchymal transition or interfering with vasopressin-induced apical AQP2 trafficking. In summary, our RNA-seq transcriptomic comparison revealed positive and negative regulatory pathways maintained by the glucocorticoid receptor for the vasopressin-induced Aqp2 gene expression.

Differentiated mouse kidney tubuloids as a novel in vitro model to study collecting duct physiology

“…Our current knowledge of kidney (patho)physiology is mainly derived from conventional research models that remain insufficient to fully elucidate certain mechanisms of kidney (patho)physiology ( Jung and Kwon, 2016 ; Edwards and Crambert, 2017 ; Kleyman and Eaton, 2019 ). And even though many models have been described, they often lack endogenous expression of relevant ion channels and transporters that are subject to physiological regulation ( Yang et al, 2022 ). Therefore, we have created tubuloids derived from mouse kidney tissue that are differentiated towards the CD, show physiological channel regulation and functional ion uptake.…”

Epac induces ryanodine receptor-dependent intracellular and inter-organellar calcium mobilization in mpkCCD cells

“…Epac-dependent Ca 2+ mobilization was associated with AVP-induced apical exocytosis in perfused IMCD. mpkCCD cells have been used as the cell model for transcriptomic and phosphoproteomic studies of AVP-signaling in the collecting duct ( Rinschen et al, 2010 ; Huling et al, 2012 ; Sandoval et al, 2013 ; Yang et al, 2022 ; Park et al, 2023 ). We have demonstrated that mpkCCD cells retain the characteristics of Epac-dependent Ca 2+ mobilization as in intact IMCD cells.…”

“…Murine principal kidney cortical collecting duct (mpkCCD) cells are commonly used cell model used for transcriptomic and phosphoproteomic studies of AVP-signaling in kidney collecting ducts ( Rinschen et al, 2010 ; Huling et al, 2012 ; Sandoval et al, 2013 ; Yang et al, 2022 ; Park et al, 2023 ). It is assumed that mpkCCD cell retains the feature of intact collecting duct cell in AVP-induced signaling events of AQP2 trafficking.…”

Glucocorticoids and Water Balance: Implications for Hyponatremia Management and Pituitary Surgery

“…Peripheral actions of glucocorticoids also affect water balance. In vitro studies of collecting duct cells suggest that glucocorticoids enhance AVP-dependent transcription of aquaporin-2 (AQP2) [26], likely due to a glucocorticoid-responsive element in the AQP2 gene promotor region [27]. In contrast, in vivo studies have demonstrated that AQP2 expression is elevated in states of glucocorticoid deficiency [28, 29].…”