Autophagy is fundamental to maintain cellular homeostasis. As one kind of the most well-studied selective autophagy, autophagy of mitochondria (mitophagy)is crucial for the clearance of damaged mitochondria. Mitophagy dysfunction has been proved to be closely associated with many human diseases. Nix is a key protein for mitophagy during the maturation of reticulocytes. However, the detailed molecular mechanisms underlying Nix-mediated mitophagy are not fully understood. This article summarizes three possible working models of Nix in mitophagy induction. Firstly, Nix can interplay with Parkin, another important protein for mitophagy, to initiate mitophagy. Secondly, Nix can serve as a receptor for autophagy machinery by interacting with Atg8 family through its LIR motif. Finally, as a BH3-only protein, Nix can compete with Beclin-1 to bind other members of Bcl-2 family resulting in increased free Beclin-1 in cytosol, which further promotes autophagy flux.
Autophagy ; genetics ; physiology ; Autophagy-Related Protein 8 Family ; physiology ; Beclin-1 ; physiology ; Membrane Proteins ; physiology ; Mitochondria ; genetics ; physiology ; Mitochondrial Degradation ; genetics ; physiology ; Protein Interaction Domains and Motifs ; Proto-Oncogene Proteins ; physiology ; Proto-Oncogene Proteins c-bcl-2 ; antagonists & inhibitors ; Tumor Suppressor Proteins ; physiology ; Ubiquitin-Protein Ligases ; physiology

OBJECTIVETo determine the role of phosphatidylinositol 3-kinase--protein kinase B (PI3K-Akt) signaling pathway in the pro- tective effect of aerobic endurance training on the skeletal muscular mitochondria.

METHODSThirty-six rats were randomly divided into three groups( n = 12): control group, aerobic endurance training group and one-time exhaustive group. After the intervention, the quadriceps femoris muscle sample was obtained to detect the mitochondrial membrane potential( MMP), the activities of succinate dehydrogenase (SDH) and cy- tochrome coxidase (COX), and the protein levels of p-PI3K and p-Akt.

RESULTSCompared with the control group, the levels of mitochondrial membrane potential, the activities of succinate dehydrogenase and cytochrome coxidase, and the protein levels of p-PI3K and p-Akt were all significantly decreased in the one-time exhaustive group (P < 0.05). However, all the above was partially reversed in the endurance training group (P < 0.05), and there was no obvious difference with the control group (P > 0.05).

CONCLUSIONAerobic endurance training plays an important role in the protective effect on the skeletal muscular mitochondria, the mechanism may be related to activation PI3K-Akt signaling pathway.

Animals ; Electron Transport Complex IV ; metabolism ; Membrane Potential, Mitochondrial ; Mitochondria ; physiology ; Muscle, Skeletal ; physiology ; Phosphatidylinositol 3-Kinases ; metabolism ; Physical Conditioning, Animal ; Proto-Oncogene Proteins c-akt ; metabolism ; Rats ; Signal Transduction ; Succinate Dehydrogenase ; metabolism

OBJECTIVEHomeopathic nosodes have seldom been scientifically validated for their anticancer effects. This study was conducted to examine if a recently developed hepatitis C nosode has demonstrable anticancer potential in cancer cells in vitro.

METHODSAnticancer effects of Hepatitis C 30C (Hep C 30), if any, were initially tested on three cancer cell lines, HepG2 (liver cancer), MCF-7 (breast cancer) and A549 (lung cancer) and one normal liver cell line WRL-68 cells and subsequently a more thorough study using further scientific protocols was undertaken on HepG2 cells (against WRL-68 cells as the normal control) as HepG2 cells showed better anticancer response than the other two. Three doses, one at 50% lethal dose (LD50) and the other two below LD50, were used on HepG2 cells subsequently. Protocols like apoptosis induction and its possible signaling mechanism were deployed using immunoblots of relevant signal proteins and confocal microscopy, with particular reference to telomerase and topoisomerase II (Top II) activities, two strong cancer biomarkers for their direct relationship with divisional activities of cells and DNAs.

RESULTSHep C 30 induced apoptosis, caused distorted cell morphology typical of apoptotic cells, increased reactive oxygen species generation and produced increased DNA nicks. Further it enhanced pro-apototic signal proteins like Bax, cytochrome c and inhibited anti-apoptotic signal proteins, Bcl-2, cytochrome c and caspase-3, changed mitochondrial membrane potential and caused externalization of phosphatidylserine. The drug also decreased expression of two cancer biomarkers, Top II and telomerase, consistent with its anticancer effect.

CONCLUSIONHep C 30 has demonstrable anticancer effects against liver cancer cells in vitro.

Antineoplastic Agents ; pharmacology ; Apoptosis ; drug effects ; Cell Survival ; drug effects ; DNA Topoisomerases, Type II ; metabolism ; Hep G2 Cells ; Hepacivirus ; Humans ; Liver Neoplasms ; drug therapy ; enzymology ; pathology ; Materia Medica ; Mitochondria ; drug effects ; physiology ; Telomerase ; metabolism

As a kind of mitochondrial membrane protein with protein kinase activity, phosphatase and tensin homolog deleted on chromosome ten induced kinase 1 (PINK1) is involved in many biological metabolic processes. Since PINK1 had been found to be associated with Parkinson's disease, researchers have been exploring its biological function. PINK1 localizes in the outer mitochondrial membrane and regulates cell function through phosphorylating proteins. PINK1 is involved in mitochondrial function, mitochondrial morphology and mitochondrial autophagy, but the regulatory pathway is not yet clear. PINK1 is expressed widely in many tissues with a variety of biological activity, especially in tissues with high energy consumption. It may therefore be involved in the development and regulation of many diseases. Mutations in PINK1 were originally discovered to cause autosomal recessive Parkinson's disease. Recently some research has revealed that PINK1 is related to the development of neonatal hypoxic-ischemic encephalopathy, cancer, diabetes and other diseases. Studying and exploring the biological functions of PINK1 will facilitate the identification of the targets for therapeutic intervention for its related diseases. This review article mainly focuses on recent studies about the biological function and related diseases of PINK1.
Autophagy ; Diabetes Mellitus, Type 2 ; etiology ; Humans ; Hypoxia-Ischemia, Brain ; etiology ; Mitochondria ; physiology ; Neoplasms ; etiology ; Protein Kinases ; chemistry ; physiology

OBJECTIVETo observe the effect of Cornus Officinalis total glycosides (COTG) and Cornus polysaccharides (CP) on myocardial mitochondria and expression levels of glycogen synthase kinase-3β (GSK-3β) of acute myocardial infarction (AMI) rats.

METHODSThe AMI rat model was established by ligating the left anterior descending branch of coronary artery. Rats were divided into 5 groups according to random digit table, i.e., the sham-operation group, the model group, the COTG prevention group, the CP treatment group, the COTG treatment group, 12 in each group. Normal saline was administered to rats in the normal control group and the model group by gastrogavage. Corresponding medication was respectively administered to rats in the rest 3 groups by gastrogavage. The cardiac function was detected by echocardiography and hemodynamics. The infarct size was determined by Masson trichrome staining. The expression of mitochondrial biogenesis genes such as a subunit of peroxisome proliferators-activated receptor-γ coactivator-1 (PGC-1α), PGC-1β, nuclear respiratory factor-1 (NRF-1), and GSK-3P mRNA were detected by Real-time PCR.

RESULTSCompared with the sham-operation group, the myocardial infarction size increased, cardiac function decreased, the expression of PGC-1α, PGC-1β, and NRF-1 mRNA decreased, and the expression of GSK-3β mRNA increased (all P <0. 05). Compared with the model group, myocardial infarction sizes were reduced, cardiac function was improved, the expression of NRF-1 mRNA was elevated in the COTG prevention group, the CP treatment group, the COTG treatment group; the expression of the PGC-1α and PGC-1β mRNA was elevated in the COTG prevention group and the CP treatment group; the expression of GSK-3β mRNA was reduced in the CP treatment group (all P <0. 05). Compared with the CP prevention group, fractional shortening (FS) and aortic systolic blood pressure (SBP) increased in the CP treatment group; ejection fraction (EF) decreased in the CP treatment group; the expression of PGC-1α, PGC-1β, NRF-1 mRNA were reduced in the the CP treatment group and the COTG treatment group; the expression of GSK-3β mRNA decreased in the CP treatment group (all P <0. 05). Compared with the COTG treatment group, FS, EF, left ventricular end systolic pressure (LVESP), SBP, and the expression of GSK-3β mRNA were reduced in the CP treatment group (P <0. 05).

CONCLUSIONSCOTG and CP could improve cardiac function, reduce the myocardial infarction area, and promote biogenesis of myocardial mitochondria. Their protective effects on the mitochondria of cadiocytes might be achieved by GSK-3β signalina pathway.

Animals ; Cornus ; Drugs, Chinese Herbal ; pharmacology ; therapeutic use ; Glycogen Synthase Kinase 3 ; Glycogen Synthase Kinase 3 beta ; Glycosides ; Heat-Shock Proteins ; Mitochondria, Heart ; physiology ; Myocardial Infarction ; Peroxisome Proliferator-Activated Receptor Gamma Coactivator 1-alpha ; Polysaccharides ; Protective Agents ; pharmacology ; therapeutic use ; RNA, Messenger ; Rats ; Rats, Sprague-Dawley ; Transcription Factors

OBJECTIVETo detect the levels of miR-499 and relative proteins in hearts of mice after exercise training, and investigate the mechanism of exercise-regulative apoptosis.

METHODSMale C57BL/6 mice were randomly divided into 3 groups( n = 14): sedentary (SE), exercise training 1 (ET1) and exercise training 2 (ET2) group. SE did not do any exercise. ET1 performed swimming training for 8 weeks. ET2 performed the same work as ET1 until the 5th week. Then, mice trained twice a day until the end of training. TUNEL assay was applied to test myocardial apoptosis, RT-PCR and Western blot were used to detect miR-499 and proteins levels respectively.

RESULTSCompared with SE, stress in ET1 failed to affect apoptotic index (AI) and miR-499-CaN-Drp-1 pathway (P > 0.05). In contrast, exercise load in ET2 increased miR-499 level, decreased Drp-1 level and AI with statistical significance respectively (P < 0.05), but neither CaN expression nor CaN activity was changed significantly (P > 0.05).

CONCLUSIONSwimming training can inhibit myocardial apoptosis, and the decrease in Drp-l may be responsible for the reduced myocardial apoptosis. CaN, the upstream protein, does not participate in exercise-regulative apoptosis.

Animals ; Apoptosis ; Dynamins ; metabolism ; Heart ; Male ; Mice ; Mice, Inbred C57BL ; MicroRNAs ; metabolism ; Mitochondria, Heart ; physiology ; Myocardium ; pathology ; Physical Conditioning, Animal ; Swimming

OBJECTIVETo preliminarily investigate the long-term structural and functional injuries of mitochondria in rat brain caused by sepsis.

METHODSWistar rats were randomly assigned into sepsis and control groups. A rat model of sepsis was prepared by an intraperitoneal injection of 10 mg/kg lipopolysaccharide (LPS) of gram-negative bacteria, and the survival assay was performed. Eight rats in the sepsis group were sacrificed at 12, 24, 48, or 72 hours after LPS injection, while rats in the control group were sacrificed after an intraperitoneal injection of an equal volume of normal saline. Mitochondria were extracted from rat brain tissue. Mitochondrial membrane potential (MMP) and mitochondrial swelling level were determined by flow cytometry, and the activities of electron transport chain complexes (I-V) were measured using enzyme assay kits. Hematoxylin-eosin (HE) staining and electron microscopy were used to observe morphological changes in brain tissue and mitochondria.

RESULTSThe sepsis group had a significantly lower survival rate than the control group (P<0.01). The MMP and activities of electron transport chain complexes (I-V) in the sepsis group, which were significantly lower than those in the control group (P<0.05), were reduced to the lowest levels at 48 hours and partially recovered at 72 hours. The mitochondrial swelling level in the sepsis group, which was significantly higher than that in the control group (P<0.05), increased to the peak level at 48 hours and partially recovered at 72 hours. Hematoxylin and Eosin staining revealed substantial damages in the structure of brain tissue, and electron microscopy showed mitochondrial swelling, and vacuolization in a few mitochondria.

CONCLUSIONSIn the rat model of LPS-induced sepsis, both structural and functional injuries are found in cerebral mitochondria, and achieve the peak levels probably at around 48 hours.

Animals ; Brain ; pathology ; physiopathology ; ultrastructure ; Lipopolysaccharides ; toxicity ; Male ; Membrane Potential, Mitochondrial ; Mitochondria ; physiology ; ultrastructure ; Rats ; Rats, Wistar ; Sepsis ; chemically induced ; mortality ; physiopathology

As human beings ascend to high altitude, a number of reactions may occur against hypoxic injuries. These hypoxic responses are related to intake, transportation and utility of the oxygen. As a crucial subcellular organelle of oxygen utility, mitochondrion is a central link of high altitude acclimatization, adaptation and mountain sicknesses. In this review, we discussed the recent advances in researches on hypoxic mitochondrial responses at high altitude.
Adaptation, Physiological ; Altitude ; Altitude Sickness ; Animals ; Humans ; Hypoxia ; Mitochondria ; pathology ; Oxygen ; physiology

OBJECTIVETo observe the changes of mitochondria stress in locus coeruleus and the tyrosine hydroxylasic projection after long-term sleep deprivation.

METHODSSleep deprivation mice model was set up by employing "novel environments" method. The expression of NAD -dependent deacetylase Sirtuin type 3 (SIRT3), which regulates mitochondrial energy production and oxidative stress, and heat shock protein 60 (HSP60), a major biomarker of mitochondrial stress, and the tyrosine hydroxylasic projection from locus coeruleus were analyzed after a 5-day sleep deprivation.

RESULTSCompared to the control group, the expression of SIRT3 in locus coeruleus was significantly decreased in respouse to long-term sleep deprivation, while the expression of HSP60 was significantly increased. In addition, relative to control group, pereentage area of the tyrosine hydroxylasic projection to anterior cingulate cortex was substantial decreased in long-term sleep deprivation group.

CONCLUSIONLong-term sleep deprivation induced the decreased level of SIRT3 expression and the elevation of mitochondrial stress in locus coenileus, which may further lead to the loss of tyrosine hydroxylasic projection in mice.

Animals ; Chaperonin 60 ; metabolism ; Locus Coeruleus ; metabolism ; physiology ; Mice ; Mitochondria ; metabolism ; Mitochondrial Proteins ; metabolism ; Oxidative Stress ; physiology ; Sirtuin 3 ; metabolism ; Sleep Deprivation ; Tyrosine ; metabolism

The effects of mouse oocyte vitrification on mitochondrial membrane potential and distribution were explored in this study. The collected mouse oocytes were randomly divided into vitrification and control groups. Ethylene glycol (EG) and dimethylsulphoxide (DMSO) were used as cryoprotectants in the vitrification group. The mitochondrial function and distribution in the oocytes were examined by using the fluorescent probes, JC-1 and Mito Tracker green. The results showed that the ratio of red to green fluorescence in mouse oocytes was significantly decreased after thawing in the vitrification group as compared with the control group (1.28 vs. 1.70, P<0.05). The percentage of polarized distribution of the mitochondria in oocytes was conspicuously reduced in the vitrification group when compared with the control group (31% vs. 63%, P<0.05). It was suggested that vitrification significantly affects the mitochondrial function and distribution in oocytes and reduces the potential of oocyte fertilization and embryo development.
Animals ; Cryopreservation ; methods ; Cryoprotective Agents ; pharmacology ; Dimethyl Sulfoxide ; pharmacology ; Ethylene Glycol ; pharmacology ; Female ; Fluorescent Dyes ; metabolism ; Membrane Potential, Mitochondrial ; drug effects ; physiology ; Mice ; Microscopy, Fluorescence ; Mitochondria ; drug effects ; metabolism ; Oocytes ; drug effects ; physiology ; Temperature ; Vitrification