SIRT7 silencing by miR-152-3p confers cell apoptosis and renal functional impairment induced by renal ischaemia/reperfusion injury.

PURPOSE: Acute kidney injury (AKI) induced by renal ischaemia/reperfusion (I/R) during renal transplantation has been reported to be linked to the regulation of SIRT2, one of the members of SIRTUINS family. Current work is attempted to explore the influence and mechanism of SIRT7 in renal cell apoptosis controlled by miR-152-3p during renal I/R injury. METHODS: Three databases were used to select the miRNAs regulating the expression of SIRT7. Overexpression and inhibition of miR-152-3p and Luciferase assay were employed to certify the modulation of miR-152-3p to SIRT7 in cells. RT-qPCR assay was used to measure the mRNA levels. Western blot assay was employed to determine the expression of proteins. TUNEL assay and Flow Cytometry were conducted to analyze cell apoptosis. RESULTS: SIRT7 expression decreased in tissues of AKI patients and rats underwent renal I/R, which was associated with enhanced impairment of renal function. SIRT7 downregulation was attributed to the direct inhibition by miR-152-3p due to binding and inhibiting its seed sequence in 3'-UTR of SIRT7 mRNA. Consequently, the upregulation of miR-152-3p led to an inhibition of SIRT7 expression, an increase in expression of extrinsic apoptosis molecules containing FOXO3a, Bim, and caspase3, and apoptotic renal cells; while miR-152-3p inhibition abolished these phenotypes. CONCLUSION: SIRT7 downregulation by miR-152-3p is a leading cause of renal cell apoptosis and functional impairment induced by renal I/R. Inhibition of miR-152-3p to restore SIRT7 expression can be a promising strategy against renal I/R injury.

Association of T2285C polymorphism in PARP1 gene coding region with its expression, activity and NSCLC risk along with prognosis.

Poly (ADP-ribose) polymerase-1 (PARP1), a DNA repair gene, is the crucial player in the maintenance of genome integrity. T2285C polymorphism in coding region of PARP1 has been reported to be associated with susceptibility to tumours. We explored the relationship and mechanism of T2285C polymorphism of PARP1 to its expression and activity along with risk and prognosis in non-small cell lung cancer (NSCLC). mRNA expression was measured using quantitative RT-PCR assay or collected from TCGA dataset. Protein expression was examined with immunoblotting assay. Genotypes were determined by PCR-RFLP and sequencing approaches. PARP1 activity was determined with enzyme activity assay. Regulation of SIRT7 to PARP1 was determined by overexpression and small interference experiment. Association of PARP1 T2285C polymorphism with NSCLC risk was evaluated via multiple logistic regression analysis. Comparison of treatment response and progression-free survival (PFS) of NSCLC patients among different genotypes or regimens was made by chi-square test. Results indicated that mRNA and protein expression of PARP1 dramatically increased in NSCLC tissues in comparison with paired para-carcinoma tissues (P < 0.05). TC/CC mutant genotypes were associated with markedly enhanced PARP1 mRNA level compared with TT genotype (P = 0.011). No significant difference was discovered in PARP1 protein expression among TT, TC or CC genotypes (P > 0.05). Subjects with variant allele C had higher risk of NSCLC in comparison with allele T carriers [odds ratio = 1.560; P = 0.000]. NSCLC patients carrying mutational TC or CC genotypes were correlated with unfavourable response to platinum-based chemotherapy (TT vs. TC vs. CC, P = 0.010), and shorter PFS compared with TT genotype (TT vs. TC vs. CC, P = 0.009). T2285C mutation of PARP1 resulted in the enhancement of its mRNA, but the decrease of enzyme activity in tumour cell. Overexpression of SIRT7 attenuated PARP1 expression and activity. These findings suggest the variant allele C of T2285C polymorphism of PARP1 linked to an increase of NSCLC risk, and unfavourable efficacy and prognosis of NSCLC patients with platinum-based chemotherapy, which might be associated with enhancement of its mRNA expression and the diminishment of activity. Identification of PARP1 T2285C polymorphism and mRNA expression may be the promising way for the individualised treatment of NSCLC.

SIRT2 tyrosine nitration by peroxynitrite in response to renal ischemia/reperfusion injury.

Reactive oxygen species (ROS) and reactive nitrogen species (RNS) are the production of renal ischemia/reperfusion (I/R). The current study is to elucidate a mechanism of SIRT2 tyrosine nitration to accelerate the cell apoptosis induced by peroxynitrite (ONOO‾), the most reactive and deleterious RNS type in renal ischemia/reperfusion (I/R) injury. Our results demonstrate that there is a significant enhancement of the 3-nitrotyrosine levels in renal tissues of Acute Kidney Injury (AKI) patients and rats that underwent renal I/R, and a positive correlation between the 3-nitrotyrosine level and renal function impairment, indicative of an accumulation of peroxynitrite. Notably, peroxynitrite-evoked nitration of SIRT2 destroyed its enzymatic activity and the capability to deacetylate FOXO3a, and enhanced expression of Bim and caspase3, facilitating renal cell apoptosis in renal ischemia/reperfusion and SIN-1(peroxynitrite donor) treatment in vitro, and these effects were reversed by FeTMPyP, a peroxynitrite decomposition scavenger. Importantly, we identified that the tyrosine 86 is responsible for SIRT2 nitration and inactivation using site-mutation assay and Mass Spectrography analysis. Altogether, these findings point to a novel protective mechanism that an inhibition of SIRT2 tyrosine nitration can be a promising strategy to prevent ischemic renal diseases involving AKI.