NMDA Receptor-mediated CaMKII/ERK Activation Contributes to Renal Fibrosis

Abstract

Background: Renal fibrosis (RF) results in renal function impairment and eventually kidney failure. We found that N-methyl-D-aspartate receptor (NMDAR) played an important role during RF. However, its mechanism of action is yet to be deciphered. Methods: Acute RF was induced in mice by unilateral ureteral obstruction (UUO). NR1, which is the functional subunit of NMDAR, was downregulated using lentiviral vector-mediated shRNA interference. Histological changes were observed by Masson’s trichrome staining. Expression of NR1, fibrotic and EMT markers were measured by immunohistochemistry and western blot analysis. HK-2 cells were incubated with TGF-β, and NMDAR antagonist MK-801 and Ca2+/calmodulin-dependent protein kinase II (CaMKII) antagonist KN-93 administration were further included in this study for pathway determination. Expression of NR1, total and phosphorylated CaMKII, total and phosphorylated ERK were measured using western blot and immunofluorescent assays. Chronic renal fibrosis was introduced by sublethal ischemia-reperfusion injury in mice, and oral NMDAR inhibitor dextromethorphan (DXM) administration was performed. Results: NR1 expressions were upregulated in both obstructed kidneys and TGF-β treated HK-2 cells. NR1 knockdown, DXM, MK801, and KN93 reduced the fibrotic morphology in vivo and in vitro respectively, and companied with the downregulated ERK activation, while KN93 administration had no effect on NR1 and CaMKII levels. Conclusions: NMDAR participates in both acute and chronic renal fibrogenesis via CaMKII/ERK activation, and is a potential therapeutic target for renal fibrosis.

Inhibition of histone readers bromodomain extra-terminal proteins alleviates skin fibrosis in experimental models of scleroderma

“…We showed similar findings in dcSSc fibroblasts in this study. In addition to cardiac fibrosis, CaMKII is also involved in pulmonary fibrosis (32), ureteral scar formation (33), and renal fibrosis (34). CaMKII has been shown to be associated with FGFR3/FGF9 in SSc fibroblasts, functioning as a downstream mediator for the pro-fibrotic effect of FGFR3 (25).…”

NMDARs antagonist MK801 suppresses LPS-induced apoptosis and mitochondrial dysfunction by regulating subunits of NMDARs via the CaM/CaMKII/ERK pathway

“…Previous evidence has demonstrated the binding of calmodulin (CaM) to NMDARs is required for CaM-dependent inactivation of NMDAR, and NMDARs-mediated CaMKII/ERK activation contributes to renal fibrosis [17,18], indicated CAM, CAMKII, and ERK pathways are essential for NMDARs regulated cell function. To determine whether CAM, CAMKII, and ERK are involved in the effect of MK801 on LPS-induced cell injury and mitochondrial dysfunction, we examined the expression of CaM, CaMKII, Erk, MCU, a mitochondrial inner membrane calcium uniporter, and its receptor MCUR1, as well as TLR4.…”