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Na/K-ATPase/src complex mediates regulation of CD40 in renal parenchyma.

ABSTRACT: Background:Recent studies have highlighted a critical role for CD40 in the pathogenesis of renal injury and fibrosis. However, little is currently understood about the regulation of CD40 in this setting. Methods:We use novel Na/K-ATPase cell lines and inhibitors in order to demonstrate the regulatory function of Na/K-ATPase with regards to CD40 expression and function. We utilize 5/6 partial nephrectomy as well as direct infusion of a Na/K-ATPase ligand to demonstrate this mechanism exists in vivo. Results:We demonstrate that knockdown of the ?1 isoform of Na/K-ATPase causes a reduction in CD40 while rescue of the ?1 but not the ?2 isoform restores CD40 expression in renal epithelial cells. Second, because the major functional difference between ?1 and ?2 is the ability of ?1 to form a functional signaling complex with Src, we examined whether the Na/K-ATPase/Src complex is important for CD40 expression. We show that a gain-of-Src binding ?2 mutant restores CD40 expression while loss-of-Src binding ?1 reduces CD40 expression. Furthermore, loss of a functional Na/K-ATPase/Src complex also disrupts CD40 signaling. Importantly, we show that use of a specific Na/K-ATPase/Src complex antagonist, pNaKtide, can attenuate cardiotonic steroid (CTS)-induced induction of CD40 expression in vitro. Conclusions:Because the Na/K-ATPase/Src complex is also a key player in the pathogenesis of renal injury and fibrosis, our new findings suggest that Na/K-ATPase and CD40 may comprise a pro-fibrotic feed-forward loop in the kidney and that pharmacological inhibition of this loop may be useful in the treatment of renal fibrosis.

SUBMITTER: Xie JX

PROVIDER: S-EPMC6031043 | biostudies-literature | 2018 Jul

REPOSITORIES: biostudies-literature

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Na/K-ATPase/src complex mediates regulation of CD40 in renal parenchyma.

Xie Jeffrey X JX Zhang Shungang S Cui Xiaoyu X Zhang Jue J Yu Hui H Khalaf Fatimah K FK Malhotra Deepak D Kennedy David J DJ Shapiro Joseph I JI Tian Jiang J Haller Steven T ST

Nephrology, dialysis, transplantation : official publication of the European Dialysis and Transplant Association - European Renal Association 20180701 7

<h4>Background</h4>Recent studies have highlighted a critical role for CD40 in the pathogenesis of renal injury and fibrosis. However, little is currently understood about the regulation of CD40 in this setting.<h4>Methods</h4>We use novel Na/K-ATPase cell lines and inhibitors in order to demonstrate the regulatory function of Na/K-ATPase with regards to CD40 expression and function. We utilize 5/6 partial nephrectomy as well as direct infusion of a Na/K-ATPase ligand to demonstrate this mechani ...[more]

PMID: 29294050

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Project description:The Na/K-ATPase is an important membrane ion transporter and a signaling receptor that is essential for maintaining normal cell function. The current study examined the role of Na/K-ATPase signaling in regulating miR-29b-3p, an anti-fibrotic microRNA, in a mouse chronic kidney disease (CKD) model (5/6th partial nephrectomy or PNx). The results showed that CKD induced significant reduction of miR-29b-3p expression in the heart tissue by activation of Src and NF?B signaling in these animals. To demonstrate the role of Na/K-ATPase signaling, we also performed the PNx surgery on Na/K-ATPase ?1 heterozygous (?1+/-) mice, which expresses ~40% less Na/K-ATPase ?1 compared to their wild type littermates (WT) and exhibits deficiency in Na/K-ATPase signaling. We found that CKD did not significantly change the miR-29b-3p expression in heart tissue from the ?1+/- animals. We also found that CKD failed to activate Src and NF?B signaling in these animals. Using isolated cardiac fibroblasts from ?1+/- mice and their WT littermates, we showed that ouabain, a specific Na/K-ATPase ligand, induces decreased miR-29b-3p expression in fibroblasts isolated from WT mice, but had no effect in cells from ?1+/- mice. Inhibition of NF?B by Bay11-7082 prevented ouabain-induced miR-29b-3p reduction in WT fibroblasts. To further confirm the in vivo effect of Na/K-ATPase signaling in regulation of miR-29b-3p and cardiac fibrosis in CKD animals, we used pNaKtide, a Src inhibiting peptide derived from the sequence of Na/K-ATPase, to block the activation of Na/K-ATPase signaling. The result showed that pNaKtide injection significantly increased miR-29b-3p expression and mitigated the CKD-induced cardiac fibrosis in these animals. These results clearly demonstrated that Na/K-ATPase signaling is an important mediator in CKD that regulates miR-29b-3p expression and cardiac fibrosis, which provides a novel target for regulation of miR-29b-3p in CKD. We also demonstrate that antagonizing Na/K-ATPase signaling by pNaKtide can reduce organ fibrosis through the stimulation of tissue miR-29b-3p expression.

Dataset Information

Na/K-ATPase/src complex mediates regulation of CD40 in renal parenchyma.

Publications

Na/K-ATPase/src complex mediates regulation of CD40 in renal parenchyma.

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