Effect of mitochondrial tRNA(Lys) mutation on the clinical and biochemical characteristics of Chinese essential hypertensive subjects

Mitochondrial DNA 7908-8816 region mutations in maternally inherited essential hypertensive subjects in China

Background

Nuclear genes or family-based mitochondrial screening have been the focus of genetic studies into essential hypertension. Studies into the role of mitochondria in sporadic Chinese hypertensives are lacking. The objective of the study was to explore the relationship between mitochondrial DNA (mtDNA) variations and the development of maternally inherited essential hypertension (MIEH) in China.

Methods

Yangzhou residents who were outpatients or in-patients at the Department of Cardiology in Northern Jiangsu People’s Hospital (Jiangsu, China) from June 2009 to June 2015 were recruited in a 1:1 case control study of 600 gender-matched Chinese MIEH subjects and controls. Genomic DNA was isolated from whole blood cells. The most likely sites for hypertension were screened using oligodeoxynucleotides at positions 7908–8816, purified and subsequently analyzed by direct sequencing according to the revised consensus Cambridge sequence. The frequency, density, type and conservative evolution of mtDNA variations were comprehensively analyzed.

Results

We found a statistical difference between the two groups for body mass index, waist circumference, abdominal circumference, triglyceride, low-density lipoprotein cholesterol, fasting blood glucose, uric acid, creatinine and blood urea nitrogen (P < 0.05). More amino-acid changes and RNA variants were found in MIEH subjects than the controls (P < 0.01). The detection system simultaneously identified 40 different heteroplasmic or homoplasmic mutations in 4 genes: COXII, tRNA^Lys, ATP8 and ATP 6. The mtDNA variations were mainly distributed in regions of ATP6 binding sites, and the site of highest mutation frequency was m. 8414C > T. Three changes in single bases (C8414T in ATP8, A8701G in ATP6 and G8584A in ATP6) were significantly different in the MIEH patients and the controls (P < 0.001). The m.8273_8281del mutation was identified from 59 MIEH patients.

Conclusions

Our results indicate that novel mtDNA mutations may be involved in the pathological process of MIEH, and mitochondrial genetic characteristics were identified in MIEH individuals.

Electronic supplementary material

The online version of this article (10.1186/s12920-018-0408-0) contains supplementary material, which is available to authorized users.

miR-217 regulates tumor growth and apoptosis by targeting the MAPK signaling pathway in colorectal cancer

MicroRNA (miR)-217 has been reported to participate in carcinogenesis and tumor progression in several cancers; however, its expression and biological functions in colorectal cancer (CRC) are still unclear. The present study demonstrated that miR-217 expression was significantly higher in matched adjacent noncancerous tissues than in CRC tissues (P<0.001). In addition, it was observed that low-grade CRC exhibited greater expression of miR-217 compared with high-grade CRC (P<0.05). Kaplan-Meier survival and Cox regression analyses revealed that overall survival rates were significantly poorer in the low-expression group relative to the high-expression group (P<0.005). Next, a potential miR-217 target, mitogen-activated protein kinase (MAPK) 1, was identified. Upregulation of miR-217 could significantly downregulate MAPK1 expression. CRC cells overexpressing miR-217 exhibited cell growth inhibition by significant enhancement of apoptosis in vitro. The present study further investigated the MAPK signaling pathway to verify the mechanisms, and revealed that KRAS and Raf-1 expression was downregulated in miR-217-overexpressing RKO cells. Taken together, our results revealed that miR-217 inhibits tumor growth and enhances apoptosis in CRC, and that this is associated with the downregulation of MAPK signaling. These results indicate that miR-217 is a promising therapeutic target for the treatment of CRC.