ROS act as an upstream signal to mediate cadmium-induced mitophagy in mouse brain

As a well known generator of reactive oxygen species (ROS), cadmium (Cd) is found to be an effective inducer of mitophagy in mouse kidney and liver cells. Here, we aim to elucidate whether Cd can also initiate mitophagy in mouse brain and what role ROS play in this process. Our results showed that Cd caused overproduction of ROS. Meanwhile, Cd induced mitophagy, as indicated by the collapse of mitochondrial membrane potential (MMP), formation of mitophagosomes, increases of PINK1 level and LC3-II/LC3-I ratio and decrease of mitochondrial mass. Scavenging of ROS by N-acetyl-l-cysteine (NAC) or acetyl-l-carnitine (ALC) rescued MMP and mitochondrial mass, and squelched PINK1 level, mitochondrial accumulation of Parkin and LC3-II/LC3-I ratio, suggesting that ROS were associated with Cd-induced mitophagy. Cyclosporine A (CsA), an inhibitor of mitophagy, blocked Cd-induced mitophagy and PINK1/Parkin pathway but failed to suppress ROS increase, revealing that ROS are the causes rather than the results of Cd-induced mitophagy. In conclusion, this study suggested that ROS functioned on the upstream of PINK1/Parkin pathway to mediate Cd-induced mitophagy.     

Calcium,mitochondria and the initiation of acute pancreatitis

Acute pancreatitis is characterized by necrosis of its parenchymal cells and influx and activation of inflammatory cells that further promote injury and necrosis. This review is intended to discuss the central role of disorders of calcium metabolism and mitochondrial dysfunction in the mechanism of pancreatitis development. The disorders are placed in context of calcium and mitochondria in physiologic function of the pancreas. Moreover, we discuss potential therapeutics for preventing pathologic calcium signals that injure mitochondria and interventions that promote the removal of injured mitochondria and regenerate new and heathy populations of mitochondria.     

Prx1调控PINK1/Parkin介导的线粒体自噬在实验性口腔黏膜癌变中的作用

目的检测口腔黏膜癌变过程中线粒体自噬相关蛋白PINK1、Parkin表达变化及抗氧化蛋白Prx1对其调控作用,探讨Prx1在口腔黏膜癌变中的作用机制。方法利用4NQO化学诱导Prx1^+/+和Prx1+/-小鼠舌黏膜癌变模型,采用免疫组织化学染色及Q-PCR方法,检测PINK1、Parkin在小鼠舌正常黏膜、白斑、白斑伴上皮异常增生、鳞癌组织中的表达。结果在Prx1^+/+小鼠舌癌变模型中,PINK1、Parkin蛋白及mRNA表达在舌白斑及白斑伴上皮异常增生组织中显著高于正常黏膜及舌癌组织;与Prx1^+/+小鼠各组相比,Prx1敲除导致小鼠舌白斑、白斑伴上皮异常增生及舌癌中PINK1蛋白及mRNA表达明显降低;小鼠舌白斑及舌癌组织中Parkin mRNA表达显著升高。结论线粒体自噬参与了口腔黏膜癌变过程;Prx1可能通过调控PINK1/Parkin介导的线粒体自噬在其中发挥重要作用。     

自噬对肾小管细胞毒性损伤后线粒体功能的影响及相关机制研究

目的研究自噬对肾小管细胞毒性损伤后线粒体功能的影响及相关机制。方法将人近曲肾小管上皮细胞(HK-2)分为杂化siRNA组(对照无关序列片段siRNA转染细胞)、杂化siRNA+顺铂组(对照无关序列片段siRNA转染细胞+10μmol/L顺铂溶液)、沉默Pink1+顺铂组(Pink1沉默转染细胞+10μmol/L顺铂溶液)和沉默Parkin+顺铂组(Parkin沉默转染细胞+10μmol/L顺铂溶液)。培养12 h后,细胞计数试剂盒8(CCK-8)法测定各组细胞存活率,JC-1法检测线粒体膜电位,荧光法检测各组细胞内三磷酸腺苷(ATP)的含量,Western blotting和免疫荧光探针检测自噬相关蛋白的相对表达。结果杂化siRNA+顺铂组的细胞存活率为(88.2±2.7)%,显著低于杂化siRNA组[(101.3±3.1)%](P<0.05);沉默Pink1+顺铂组和沉默Parkin+顺铂组的存活率为(80.1±2.3)%、(79.4±3.0%),显著低于杂化siRNA+顺铂组(P<0.05)。杂化siRNA+顺铂组的线粒体膜电位和ATP含量为(0.90±0.01)、(0.82±0.01)nmol/mg,显著低于杂化siRNA组[(1.01±0.02)、(1.00±0.04)nmol/mg](P<0.05);沉默Pink1+顺铂组和沉默Parkin+顺铂组的线粒体膜电位(0.79±0.02、0.77±0.02)和ATP[(0.66±0.05)、(0.66±0.02)nmol/mg]含量显著低于杂化siRNA+顺铂组(P<0.05)。杂化siRNA+顺铂组的Pink1、Parkin、Beclin蛋白的相对表达量和LC3Ⅱ/LC3Ⅰ的比值(1.68±0.04、1.80±0.05、1.87±0.05、2.01±0.04)显著高于杂化siRNA组(1.00±0.04、1.00±0.05、1.01±0.01、1.04±0.02)(P<0.05);而沉默Pink1+顺铂组和沉默Parkin+顺铂组的Pink1、Parkin、Beclin蛋白的相对表达量和LC3Ⅱ/LC3Ⅰ的比值(1.17±0.05、0.69±0.05、1.37±0.05、1.43±0.02;1.22±0.04、0.57±0.06、1.39±0.03、1.38±0.10)显著低于杂化siRNA+顺铂组(P<0.05)。杂化siRNA+顺铂组的自噬阳性点数为(12.2±0.7)个,显著多于杂化siRNA组[(2.4±0.3)个](P<0.05);而沉默Pink1+顺铂组和沉默Parkin+顺铂组的荧光点数[(5.3±0.8)、(5.6±0.5)个]显著少于杂化siRNA+顺铂组(P<0.05)。结论顺铂处理可诱导HK-2细胞的线粒体自噬作用,从而改善顺铂引起的肾小管细胞毒性损伤和线粒体功能,其作用机制可能与Pink1/Parkin蛋白的表达情况有关。     

High-content analysis for mitophagy response to nanoparticles: A potential sensitive biomarker for nanosafety assessment

Mitophagy, a selective autophagy of mitochondria, clears up damaged mitochondria to maintain cell homeostasis. We performed high-content analysis (HCA) to detect the increase of PINK1, an essential protein controlling mitophagy, in hepatic cells treated with several nanoparticles (NPs). PINK1 immunofluorescence-based HCA was more sensitive than assays and detections for cell viability and mitochondrial functions. Of which, superparamagnetic iron oxide (SPIO)-NPs or graphene oxide-quantum dots (GO-QDs) was selected as representatives for positive or negative inducer of mitophagy. SPIO-NPs, but not GO-QDs, activated PINK1-dependent mitophagy as demonstrated by recruitment of PARKIN to mitochondria and degradation of injured mitochondria. SPIO-NPs caused the loss of mitochondrial membrane potential, decrease in ATP, and increase in mitochondrial reactive oxide species and Ca²⁺. Blocking mitophagy with PARKIN siRNA aggravated the cytotoxicity of SPIO-NPs. Taken together, PINK1 immunofluorescence-based HCA is considered to be an early, sensitive, and reliable approach to evaluate the bioimpacts of NPs.     

Mitophagy Receptors and Mediators: Therapeutic Targets in the Management of Cardiovascular Ageing

Mitophagy serves as a cardinal regulator in the maintenance of mitochondrial integrity, function, and cardiovascular homeostasis, through the fine control and governance of cellular metabolism, ATP production, redox balance, and mitochondrial quality and quantity control. As a unique form of selective autophagy, mitophagy specifically recognizes and engulfs long-lived or damaged (depolarized) mitochondria through formation of the double-membraned intracellular organelles - mitophagosomes, ultimately resulting in lysosomal degradation. Levels of mitophagy are reported to be altered in pathological settings including cardiovascular diseases and biological ageing although the precise nature of mitophagy change in ageing and ageing-associated cardiovascular deterioration remains poorly defined. Ample clinical and experimental evidence has depicted a convincing tie between cardiovascular ageing and altered mitophagy. In particular, ageing perturbs multiple enigmatic various signal machineries governing mitophagy, mitochondrial quality, and mitochondrial function, contributing to ageing-elicited anomalies in the cardiovascular system. This review will update novel regulatory mechanisms of mitophagy especially in the perspective of advanced ageing, and discuss how mitophagy dysregulation may be linked to cardiovascular abnormalities in ageing. We hope to pave the way for development of new therapeutic strategies against the growing health and socieconomical issue of cardiovascular ageing through targeting mitophagy.     

Sirtuins in mitochondrial stress: Indispensable helpers behind the scenes

Mitochondria play an essential part in guaranteeing normal cellular physiological functions through providing ATP and participating in diverse processes and signaling pathways. Recently, more and more studies have revealed the vital roles of mitochondria in coping with stressors in the aging process, metabolic disturbances and neurological disorders. Mitochondrial stress responses, including the mitochondrial unfolded protein response (UPR^mt), antioxidant defense, mitochondrial fission, mitochondrial fusion and mitophagy, are induced to maintain cellular integrity in response to stress. The sirtuin family, a group of NAD⁺-dependent deacetylases, has been the focus of much attention in recent years for their multiple regulatory functions, especially in aging and metabolism. Recent reports validated the significant link between mitochondrial stress responses and the sirtuin family, which may help to elucidate the pathogenesis and therapies for diseases such as Alzheimer’s disease or Parkinson’s disease. This review will summarize recent related studies and illuminate the interplay between sirtuins and mitochondrial stress.     

Ketoconazole exacerbates mitophagy to induce apoptosis by downregulating cyclooxygenase-2 in hepatocellular carcinoma

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神经变性疾病线粒体自噬的研究进展

细胞自噬是指细胞利用溶酶体降解自身成分的过程,被降解的成分包括细胞质以及细胞器。线粒体是自噬特异性攻击的主要靶标之一,自噬线粒体的过程,被称为线粒体自噬。线粒体自噬具有重要的生物学意义,正常情况下,帮助维持合成、降解和细胞产物循环之间的平衡,在细胞生长、发育和稳态中发挥作用。近年来,研究发现线粒体自噬异常在神经变性疾病（如帕金森病、阿尔茨海默和亨廷顿病等）的发病机制中具有重要作用。本文对此作一综述。