Dataset Information

Vitamin D receptor activation protects against myocardial reperfusion injury through inhibition of apoptosis and modulation of autophagy.

ABSTRACT:

Aims

To determine the roles of vitamin D receptor (VDR) in ischemia/reperfusion-induced myocardial injury and to investigate the underlying mechanisms involved.

Results

The endogenous VDR expression was detected in the mouse heart, and myocardial ischemia/reperfusion (MI/R) upregulated VDR expression. Activation of VDR by natural and synthetic agonists reduced myocardial infarct size and improved cardiac function. Mechanistically, VDR activation inhibited endoplasmic reticulum (ER) stress (determined by the reduction of CCAAT/enhancer-binding protein homologous protein expression and caspase-12 activation), attenuated mitochondrial impairment (determined by the decrease of mitochondrial cytochrome c release and caspase-9 activation), and reduced cardiomyocyte apoptosis. Furthermore, VDR activation significantly inhibited MI/R-induced autophagy dysfunction (determined by the inhibition of Beclin 1 over-activation, the reduction of autophagosomes, the LC3-II/LC3-I ratio, p62 protein abundance, and the restoration of autophagy flux). Moreover, VDR activation inhibited MI/R-induced oxidative stress through a metallothionein-dependent mechanism. The cardioprotective effects of VDR agonists mentioned earlier were impaired in the setting of cardiac-specific VDR silencing. In contrast, adenovirus-mediated cardiac VDR overexpression decreased myocardial infarct size and improved cardiac function through attenuating oxidative stress, and inhibiting apoptosis and autophagy dysfunction.

Innovation and conclusion

Our data demonstrate that VDR is a novel endogenous self-defensive and cardioprotective receptor against MI/R injury, via mechanisms (at least in part) reducing oxidative stress, and inhibiting apoptosis and autophagy dysfunction-mediated cell death.

SUBMITTER: Yao T

PROVIDER: S-EPMC4346660 | biostudies-literature | 2015 Mar

REPOSITORIES: biostudies-literature

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Publications

Vitamin D receptor activation protects against myocardial reperfusion injury through inhibition of apoptosis and modulation of autophagy.

Yao Tianbao T Ying Xiaoying X Zhao Yichao Y Yuan Ancai A He Qing Q Tong Huan H Ding Song S Liu Junling J Peng Xu X Gao Erhe E Pu Jun J He Ben B

Antioxidants & redox signaling 20150114 8

<h4>Aims</h4>To determine the roles of vitamin D receptor (VDR) in ischemia/reperfusion-induced myocardial injury and to investigate the underlying mechanisms involved.<h4>Results</h4>The endogenous VDR expression was detected in the mouse heart, and myocardial ischemia/reperfusion (MI/R) upregulated VDR expression. Activation of VDR by natural and synthetic agonists reduced myocardial infarct size and improved cardiac function. Mechanistically, VDR activation inhibited endoplasmic reticulum (ER ...[more]

PMID: 25365634

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Project description:Background:Oxidative stress is a major contributor to the onset and development of myocardial ischemia reperfusion injury (MIRI). Sappanone A (SA), a homoisoflavanone extracted from the heartwood of Caesalpinia sappan L., has been demonstrated to possess powerful antioxidant activity. Therefore, this study aimed to determine the protective effect of SA on MIRI and investigate its underlying mechanism. Methods:The rat hearts were isolated and underwent 30-min ischemia, followed by 120-min reperfusion to establish the MIRI model, using the Langendorff method. SA was administrated intraperitoneally into rats 1 h prior to heart isolation. The myocardial infarct size and apoptosis were measured by TTC and terminal deoxynucleotidyl transferase dUTP nick end labeling staining. Myocardial enzyme activity, MDA content and the activities of SOD and GSH-Px were detected by colorimetric spectrophotometric method. Reactive oxygen species (ROS) level was detected by DCFH-DA probe. The change in Keap1/Nrf2 signaling pathway was evaluated by Western blotting. Results:SA reduced myocardial infarct size and the release of CK-MB and LDH in a dose-dependent manner. Moreover, SA improved the recovery of cardiac function, inhibited MIRI-induced apoptosis, repressed the production of ROS and MDA, and enhanced the activities of SOD and GSH-Px. Mechanistically, SA downregulated Keap1, induced Nrf2 nuclear accumulation, and enhanced Nrf2 transcriptional activity, subsequently resulting in an increase in the expression of the Nrf2 target genes heme oxygenase-1 and NAD(P)H quinone dehydrogenase 1. Moreover, SA enhanced the phosphorylation of Nfr2, but the enhancement in Nfr2 phosphorylation was abrogated by PKC or PI3K inhibitor. Conclusion:Collectively, it was demonstrated that SA prevents MIRI via coordinating the cellular antioxidant defenses and maintaining the redox balance, by modulation of Nrf2 via the PKC or PI3K pathway. Therefore, SA was a potential therapeutic drug for treating MIRI.

Project description:The present study aimed to evaluate the role of autophagy in the protective effect of dexmedetomidine in lung injury caused by ischemia-reperfusion (IR) in rats. In total 48 adult male Sprague-Dawley rats were randomly divided into 6 groups (n=8) as follows: i) Sham group; ii) the IR group; iii) IR + 1 µg/kg dexmedetomidine preconditioning group (pre-LD); iv) IR + 10 µg/kg dexmedetomidine preconditioning group (pre-HD); v) IR + 1 µg/kg dexmedetomidine postconditioning group (post-LD); and vi) IR + 10 µg/kg dexmedetomidine postconditioning group (post-HD). After the rats were anesthetized, the hilum of the left lung was occluded with a non-invasive microvascular clip for 30 min to induce ischemia. The clip was then removed and the left lung was allowed to regain ventilation and blood for 2 h. The rats were then sacrificed, the left lung removed and the wet/dry (W/D) lung weight ratio was determined. Pathological changes to the lungs were evaluated by light and transmission electron microscopy. Furthermore, the rate of lung cell apoptosis was determined by the TUNEL assay. The expression of hypoxia-inducible factor 1α (HIF-1α), Bcl-2/adenovirus E1B 19-kDa interacting protein 3 (BNIP3), BNIP3 like (BNIP3 L) and microtubule-associated protein 1A/1B light chain 3B (LC3II) was determined by western blotting. Compared with the sham group, a significant increase in the W/D lung weight ratio, and malondialdehyde (MDA), BNIP3, BNIP3 L and LC3II levels were observed in the IR group, and HIF-1α levels and superoxide dismutase (SOD) activity were decreased. Furthermore, the W/D ratio was lower in the pre-LD and pre-HD groups than in the IR group. Additionally, SOD activity was significantly higher and MDA expression was significantly lower in the pre-LD and pre-HD groups compared with the IR group. BNIP3, BNIP3 L and LC3II protein levels were significantly lower in the pre-LD and pre-HD groups compared with the IR group, while HIF-1α was notably upregulated in the pre-LD and pre-HD groups compared with the IR group. In conclusion, the results of the present study indicate that dexmedetomidine preconditioning protects against lung injury induced by IR through inhibition of autophagy and apoptosis.

Dataset Information

Vitamin D receptor activation protects against myocardial reperfusion injury through inhibition of apoptosis and modulation of autophagy.

Aims

Results

Innovation and conclusion

Publications

Vitamin D receptor activation protects against myocardial reperfusion injury through inhibition of apoptosis and modulation of autophagy.

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