Pathologically Elevated-Cyclic Stretch Suppressed Vascular Smooth Muscle Cell Mitochondrial Biogenesis by Down-regulating PGC1α Expression / 医用生物力学

Objective To investigate the effect of pathologically elevated-cyclic stretch induced by hypertension on mitochondrial biogenesis of vascular smooth muscle cells (VSMCs), and the role of PGC1α in this process. Methods The Flexcell-5000T stretch loading system in vitro was applied to VSMCs with a frequency of 1. 25 Hz and an amplitude of 5% or 15% to simulate the mechanical environment under normal physiological or hypertensive pathological conditions respectively. Western blotting and qPCR were used to detect the expression of PGC1α, citrate synthase and mitochondrial DNA (mtDNA) copy number in VSMCs under normal physiological or hypertensive pathological conditions. VSMCs were treated with PGC1α specific activator ZLN005 to promote PGC1α expression or specific interfering fragment siRNA to inhibit PGC1α expression in order to detect the effect on citrate synthase and mtDNA copy number. Results Compared with 5% physiological cyclic stretch, 15% pathologically elevated-cyclic stretch significantly suppressed the expression of PGC1α, citrate synthase and mtDNA copy number in VSMCs. Compared with control group, the protein expression of PGC1α was significantly decreased and increased respectively. When VSMCs transfected with PGC1α siRNA or incubated PGC1α activator ZLN005, the expression of citrate synthase and mtDNA copy number were also significantly down regulated and up-regulated in VSMCs accordingly. Under physiological cyclic stretch conditions, the protein level of PGC1α was significantly down-regulated by PGC1α siRNA, which also significantly down-regulated citrate synthase expression and mtDNA copy number. The protein expression of PGC1α was significantly up-regulated by ZLN005, which also enhanced the expression of citrate synthase and mtDNA copy number. Conclusions The pathological cyclic stretch induced by hypertension significantly down-regulated the expression of citrate synthase and mtDNA copy number via suppressing the expression of PGC1α, resulting in mitochondrial dysfunction of VSMCs. PGC1α may be a potential therapeutic target molecule to alleviate the progression of hypertension.

Role of NLRP3 inflammasome and related inflammatory signaling pathways in renal ischemia-reperfusion injury / 器官移植

Renal ischemia-reperfusion injury (IRI) commonly occurs in renal transplantation, which is an important pathophysiological process that causes acute renal failure and severely affects clinical prognosis of the recipients. Inflammatory response plays a critical role in the pathogenesis and pathological process of IRI. Activated NOD-like receptor protein 3(NLRP3) inflammasome can mediate the maturation and release of various pro-inflammatory cytokines, thereby regulating the inflammatory response and relevant cell functions. In this article, the mechanism underlying NLRP3 inflammasome and its related inflammatory signaling pathway in renal IRI were reviewed, aiming to provide novel ideas for clinical prevention and treatment of renal IRI.

Mitochondrial DNA Targeting Therapies / 中国生物化学与分子生物学报

The mitochondrion is a particularly important organelle in eukaryotic cells. It contains its own genetic material and is coined as “the powerhouse of cells”. Mitochondria are involved in many cellular progresses such as cell signaling and metabolic homeostasis. Its dysfunction is linked to various human diseases, including cancer, neurodegenerative diseases, and diabetes. Mitochondrion has a unique DNA, a small size with 16 569 bp circular genome, encoding only 37 genes, which are key components of the electron transport chain (ETC) and translational machinery. Furthermore, the mutations of mitochondrion DNA correlate with some inherited disease such as Leber’ s hereditary optic neuropathy (LHON) and mitochondrial encephalopathy, lactic acidosis and stroke-like episodes (MELAS). There are very few treatments to fully cure these diseases. As a result, researchers are interested in developing a wide range of methods to understand mitochondrial functions. In this review, we mainly focus on works in targeting mitochondrial DNA, including drug modification, material delivery and gene editing.

Recent progress on the roles of DAMP and NET in organ ischemia-reperfusion injury / 器官移植

Ischemia-reperfusion injury (IRI) is a common pathophysiological phenomenon, secondary to multiple pathological processes, such as organ transplantation, acute kidney injury and myocardial infarction. IRI may significantly aggravate the severity of diseases and increase the fatality of patients. Aseptic inflammation is one of the critical mechanisms of IRI. Damage-associated molecular pattern (DAMP) is a pivotal substance, which mediates aseptic inflammation. After released into extracellular space, it could effectively activate the immune system, and initiate and maintain the inflammatory responses by binding with pattern recognition receptor (PRR). Neutrophil extracellular trap (NET) is a DNA-based network structure released by neutrophils during the process of inflammatory responses, which contains histones and multiple granular proteins. Recent studies have demonstrated that DAMP and NET may aggravate IRI via aseptic inflammation. In this article, relevant studies of DAMP, NET and their relationship in IRI were reviewed, which was of great significance for understanding the pathophysiological mechanism of IRI and studying the corresponding prevention and treatment strategies.

Correlation between D-loop SNPs of mitochondrial DNA and diffuse large B cell lymphoma / 中国肿瘤生物治疗杂志

@# Objective: To investigate the correlations between single nucleotide polymorphisms (SNPs) in the D-loop of mitochondrial DNA (mtDNA) and the disease risk as well as the prognosis of diffuse large B cell lymphoma (DLBCL). Methods: Blood samples from 108 DLBCL patients treated at the Department of Hematology of the Fourth Hospital of Heibei Medical University during July, 1991 and July 2012 were collected for this study; in addition, blood samples from 159 healthy controls during the same period were also collected. DNA was extracted according to the standard protocols for PCR amplification and SNP locus genotype analyses. The risk of D-loop SNPs was investigated by case-control study. Results: The minor alleles of nucleotides 73A/G, 263A/G, 315C/C insert were associated with a decreased risk for DLBCL. The minor allele of the nucleotides 200G/Awas associated with an increased risk for DLBCL. To further evaluate the predictive function of D-loop SNPs in DLBCL patients, five SNP sites were identified by Log-Rank test that with statistically significant prediction value of DLBCL survival in a univariate analysis. In a multivariate analysis, allele 16304 was identified as an independent predictor of DLBCL prognosis. The survival time of DLBCL patients with 16304C was significantly shorter than that of patients with 16304T (RR=0.513, 95% CI=0.266-0.989, P<0.05). Conclusion: The analysis of D-loop SNPs in mtDNA can help identifying the occurrence risks and poor prognosis subtypes of DLBCL.

The polymorphism of mtDNA HVI and the application of multiplex amplification of two mitochondrial DNA region to the species and individual identification / 中国法医学杂志

Objective To discriminate the species and individual identification with mitochondrial DNA (mtD-NA) sequencing in forensic medicine practice. Methods The multiplex PCR of mtDNA loop - D high - variation region and cytochrome- b region were investigated. The PCR products were detected with silver- stain method,followed by analysis of the PCR products with fluorescence sequence technique. Results The presence of two bands (358bp,279bp ) indicated the samples were from human, while only one band of 358bp indicated nonhuman origin. The part of mitochondrial DNA loop - D high - variation region (15997 ~ 16236) from 131 unrelated individuals of Guangdong population were sequenced. In all of these samples there were 69 nucleotide variations and 67 haplo-types.There was 2.679 mutation sites on average per person. The polymorphism was 97.92% . Conclusion The methods described here are reliable and very useful in species and personal identification of degraded samples.

The Correlation of Plasma Homocysteine and Mitochondrial DNA Content in Peripheral Blood in Healthy Women / 대한내분비학회지

BACKGROUND: Hyperhomocysteinemia is an independent risk factor for cardiovascular diseases. Previous reports showed that homocysteine damages mitochondrial gene expression, function and structure. In recent years, homocysteine and mitochondrial DNA (mtDNA) content are reported to relate with insulin resistance. The aim of this study is to investigate the correlation of plasma homocysteine level and mitochondrial DNA content in peripheral blood. METHODS: The mtDNA content, homocysteine and insulin resistance parameters were measured in healthy women (n=60). Plasma homocysteine level was measured by ion-exchange chromatography method and the mtDNA content in peripheral blood was measured by real time PCR method using ABI Prism 7700 machine. RESULTS: Significant correlation was found between homocysteine and mtDNA content (r=-0.507, p<0.05). Homocysteine was correlated with age (r=0.397), cholesterol (r=0.327), LDL-cholesterol (r=0.318), apolipoprotein B (r=0.387), HbA1c (r=0.274) positively and folate (r=-0.262), apolipoprotein A1 (r=-0.293), VO2max (r=-0.332) negatively. Mitochondrial DNA content was correlated with age (r=-0.535), BMI (r=-0.397), cholesterol (r=-0.340), LDL-cholesterol (r=-0.319), apolipoprotein B (r=-0.367) negatively and apolipoprotein A1 (r=0.346), lactate (r=0.307), VO2max (r=0.308) positively. All correlations were statistically significant(p<0.05). CONCLUSION: In this study, plasma homocysteine level was related with mitochondrial DNA content negatively and these two factors are estimated to be concerned with insulin resistance.

Mitochondrial DNA Large Deletions in Spiral Ganglion of Cochlear and Cochlear Nucleus of Brain in Elder Rat Associated with Presbyacusis / 听力学及言语疾病杂志

Objective To investigate the possible association of mtDNA deletion in spiral ganglion of cochlear and cochlear nucleus of brain in young and elder rat with presbyacusis.Methods The mtDNA 4834 deletion in spiral ganglion of cochlear and cochlear nucleus of brain in rat was analyed by PCR.Results The deletion rate of mtDNA 4834 in rat with presbyacusis was 66.7% in spiral ganglion, 100% in cochlear nucleus of brain.While no deletion was detected in young rat.Conclusion Deletion in mtDNA of the spiral ganglion of cochlear and cochlear nucleus of brain was found in rat with presbyacusis, and it may play an important role in the pathogens of presbyacusis.

A STUDY OF HUMAN MITOCHONDRIAL DNA POLYMORPHISM REGION SEQUENCING / 中国法医学杂志

By means of Polymerase chain reaction (PCR), the mitochondrial DNA polymorphous region from the base number 15997 to 16401 was amplified. After purification,the amplified fragment was directly Sequenced on automatic .DNA sequencer and accurate results was obtained. Compared with the former reports, there are base divergence between the results of this paper and sequence of Caucasian. Changes of base in six samples were observed.The numbers of base change are 3 to 6. The maternal inheritance of the mitochondrial genome makes mtDNA sequencing via PCR an attractive tool for testing whether individuals are maternally related. The method can also be used for studying of race inheritance and molecular evolution. The method is rather simpler and quicker than the former methods.