Raf kinase inhibitor protein mediates myocardial fibrosis under conditions of enhanced myocardial oxidative stress

Abstract

Fibrosis is a hallmark of maladaptive cardiac remodelling. Here we report that genome-wide quantitative trait locus (QTL) analyses in recombinant inbred mouse lines of C57BL/6 J and DBA2/J strains identified Raf Kinase Inhibitor Protein (RKIP) as genetic marker of fibrosis progression. C57BL/6 N-RKIP−/− mice demonstrated diminished fibrosis induced by transverse aortic constriction (TAC) or CCl4 (carbon tetrachloride) treatment compared with wild-type controls. TAC-induced expression of collagen Iα2 mRNA, Ki67+ fibroblasts and marker of oxidative stress 8-hydroxyguanosine (8-dOHG)+ fibroblasts as well as the number of fibrocytes in the peripheral blood and bone marrow were markedly reduced in C57BL/6 N-RKIP−/− mice. RKIP-deficient cardiac fibroblasts demonstrated decreased migration and fibronectin production. This was accompanied by a two-fold increase of the nuclear accumulation of nuclear factor erythroid 2-related factor 2 (Nrf2), the main transcriptional activator of antioxidative proteins, and reduced expression of its inactivators. To test the importance of oxidative stress for this signaling, C57BL/6 J mice were studied. C57BL/6 J, but not the C57BL/6 N-strain, is protected from TAC-induced oxidative stress due to mutation of the nicotinamide nucleotide transhydrogenase gene (Nnt). After TAC surgery, the hearts of Nnt-deficient C57BL/6 J-RKIP−/− mice revealed diminished oxidative stress, increased left ventricular (LV) fibrosis and collagen Iα2 as well as enhanced basal nuclear expression of Nrf2. In human LV myocardium from both non-failing and failing hearts, RKIP-protein correlated negatively with the nuclear accumulation of Nrf2. In summary, under conditions of Nnt-dependent enhanced myocardial oxidative stress induced by TAC, RKIP plays a maladaptive role for fibrotic myocardial remodeling by suppressing the Nrf2-related beneficial effects.Electronic supplementary materialThe online version of this article (10.1007/s00395-018-0700-3) contains supplementary material, which is available to authorized users.

Hippo/Mst1 overexpression induces mitochondrial death in head and neck squamous cell carcinoma via activating β-catenin/Drp1 pathway

“…In Fig. 1e-h, compared with the control group, the number of TUNEL-positive cells was significantly increased in response to ad-Mst1 transfection (Kazakov et al 2018), suggesting that Mst1 overexpression activated apoptosis in SCCHN Cal27 cells and Tu686 cells. Besides, the activity of caspase-3 activity was also elevated in response to Mst1 overexpression, when compared with the control group (Fig.…”

Tanshinone IIA attenuates cardiac microvascular ischemia-reperfusion injury via regulating the SIRT1-PGC1α-mitochondrial apoptosis pathway

“…Following the addition of Sorensen's buffer (Ren et al 2018), the absorbance at the wavelength of 570 nm was determined (Jeelani et al 2018). To detect DNA fragmentation in the cell nuclei (a marker of apoptosis in testicular tissue) (Kazakov et al 2018), a TUNEL assay was performed using an In Situ Cell Death Detection Kit (Roche Diagnostics GmbH, Mannheim, Germany) according to the manufacturer's protocol. DAPI was used to label the nuclei (at room temperature for approximately 30 min) (Lee et al 2018).…”

MKP1 reduces neuroinflammation via inhibiting endoplasmic reticulum stress and mitochondrial dysfunction

“…Immunofluorescence assay analysis was carried out as previously described (Biernacki et al, 2018;Cameron et al, 2018). The primary antibodies used in the present study were p-JNK (1:1000; #9251; Cell Signaling Technology), CHOP (1:1000; #ab11419; Abcam), and PERK (1:1000; #ab65142; Abcam; Kazakov et al, 2018;Y. Zhang et al, 2019).…”