Mitochondrial dynamics, involving mitochondrial fusion, fission and autophagy, plays an important role in maintaining cellular physiological function and homeostasis. Mitochondria are the "energy plant" of human body, so the changes of mitochondrial fusion, division and autophagy are important for cell respiration and energy production. On the other hand, energy metabolism influences mitochondrial dynamics in turn. This paper reviewed the recent advances in studies on the relationship between energy metabolism and the proteins regulating mitochondrial fusion, fission and autophagy. The association of mitochondrial dynamics with electron chain complex expression, oxidative phosphorylation and ATP synthesis upon exercise intervention will provide theoretical references for the further studies in sports training and disease intervention.
Adenosine Triphosphate ; biosynthesis ; Autophagy ; Energy Metabolism ; Exercise ; Humans ; Mitochondria ; physiology ; Mitochondrial Dynamics ; Mitochondrial Proteins ; metabolism

To establish the Chang liver cell line stably overexpressing human uncoupling protein 2 (UCP2) and observe the effect of UCP2 on mitochondrial membrane potential (MMP) and reactive oxygen species (ROS). The Chang liver cell line was transfected with recombinant plasmid containing full-length human UCP2 cDNA (pcDNA3.1-hUCP2) or pcDNA3.1 empty vector. The stable cell line was established by antibiotic screening with Zeocin. UCP2 expression was detected by Western blotting and immunocytochemistry. The UCP2 overexpressing cells were pretreated with genipin at various doses (25, 50 and 100 munol/L). MMP and intracellular ROS were detected by fluorescence spectrophotometry. The total normalized protein content in UCP2 overexpressing cells was 1.6-fold higher than that in unmanipulated normal cells. The fluorescence intensities of Rhodamine123 and DCFH-DA in UCP2 overexpressing Chang liver cells (11.11+/-2.76 and 4.97+/-0.62, respectively) were significantly lower than those in unmanipulated normal cells (15.56+/-2.55, P less than 0.01 and 6.14+/-1.25, P less than 0.05, respectively) and in cells transfected with empty vector (16.11+/-2.93, P less than 0.01 and 6.23+/-1.13, P less than 0.05, respectively). Treatment of UCP2 overexpressing cells with 25, 50 and 100 munol/L genipin caused a dose-dependent increase in fluorescence intensities of Rhodamine123 (14.89+/-2.89, 17.89+/-2.93 and 24.00+/-2.55, respectively, all P less than 0.01) and DCFH-DA (9.16+/-0.78, 10.84+/-1.09 and 11.83+/-1.25, respectively, all P less than 0.01). The Chang liver cell line stably overexpressing UCP2 was established successfully. Using this cell system, UCP2 was found to play a role in mitochondrial function by regulating MMP and ROS.
Cell Line ; Hepatocytes ; metabolism ; Humans ; Ion Channels ; biosynthesis ; Membrane Potential, Mitochondrial ; Mitochondrial Proteins ; biosynthesis ; Reactive Oxygen Species ; metabolism ; Uncoupling Protein 2

Animals ; Fatty Liver ; metabolism ; Humans ; Ion Channels ; biosynthesis ; genetics ; physiology ; Mitochondrial Proteins ; biosynthesis ; genetics ; physiology ; RNA, Messenger ; biosynthesis ; genetics ; Uncoupling Protein 2

OBJECTIVETo investigate the effects of overexpression of second mitochondria-derived activator of caspases (Smac) gene on apoptosis of gastric cancer cells.

METHODSUnder the induction of liposome, MKN-45 cells were transfected by Smac gene and incubated with G418 for subclone selection. Reverse transcriptase-polymerase chain reaction and Western blot were used to determine cellular Smac gene expression. After induction of apoptosis by mitomycin (MMC), cell viabilities were analyzed using trypan blue stain. Apoptosis was measured by electronic microscopy, acridine orange-ethidium bromide fluorescent staining and in situ terminally labelled transferase technique (TUNEL). Western blot and colorimetry were used to assess cellular caspase-3 expression and its activity.

RESULTSThe Smac mRNA and protein levels in MKN-45/Smac subclone cells (subclone consistently expressing Smac gene) were significantly higher than those in MKN-45 (P < 0.01). When compared with those in MKN-45, cell viabilities of MKN-45/Smac were reduced by 10.0% to 30.8% (P < 0.01), after treatment with 10 microg/ml MMC for 6 to 24 hours. Some of the MKN-45/Smac cells showed characteristic morphologic changes of apoptosis, their apoptotic rate being increased by 21.2% (P < 0.01). After treatment with MMC, caspase-3 expression and its activity in MKN-45/Smac cells were significantly higher than those in MKN-45 (P < 0.01).

CONCLUSIONSOverexpression of Smac in gastric cancer cell line significantly improves expression and activity levels of caspase-3 after induction by MMC. Such apoptosis-inducing effect establishes a novel strategy for regulating the apoptosis activity of gastric cancer.

Apoptosis ; Caspase 3 ; metabolism ; Cell Line, Tumor ; Humans ; Intracellular Signaling Peptides and Proteins ; genetics ; Mitochondrial Proteins ; biosynthesis ; genetics ; Mitomycin ; pharmacology ; RNA, Messenger ; biosynthesis ; genetics ; Stomach Neoplasms ; metabolism ; pathology ; Transfection

Mammalian mitochondrial genome encodes a small set of tRNAs, rRNAs, and mRNAs. The RNA synthesis process has been well characterized. How the RNAs are degraded, however, is poorly understood. It was long assumed that the degradation happens in the matrix where transcription and translation machineries reside. Here we show that contrary to the assumption, mammalian mitochondrial RNA degradation occurs in the mitochondrial intermembrane space (IMS) and the IMS-localized RNASET2 is the enzyme that degrades the RNAs. This provides a new paradigm for understanding mitochondrial RNA metabolism and transport.
Cell Line ; Humans ; Mitochondrial Membranes ; metabolism ; Protein Transport ; RNA ; biosynthesis ; chemistry ; metabolism ; RNA Stability ; RNA, Mitochondrial ; Ribonucleases ; metabolism ; Tumor Suppressor Proteins ; metabolism

Mitochondrial morphology is dynamically regulated by forming small, fragmented units or interconnected networks, and this is a pivotal process that is used to maintain mitochondrial homeostasis. Although dysregulation of mitochondrial dynamics is related to the pathogenesis of several human diseases, its molecular mechanism is not fully elucidated. In this study, we demonstrate the potential role of miR-27 in the regulation of mitochondrial dynamics. Mitochondrial fission factor (MFF) mRNA is a direct target of miR-27, whose ectopic expression decreases MFF expression through binding to its 3'-untranslated region. Expression of miR-27 results in the elongation of mitochondria as well as an increased mitochondrial membrane potential and mitochondrial ATP level. Our results suggest that miR-27 is a novel regulator affecting morphological mitochondrial changes by targeting MFF.
3' Untranslated Regions ; Cell Line ; Gene Expression Regulation ; Humans ; Membrane Potential, Mitochondrial ; Membrane Proteins/*genetics ; MicroRNAs/*metabolism ; Mitochondria/*genetics/*metabolism ; *Mitochondrial Dynamics ; Mitochondrial Proteins/*genetics ; *Protein Biosynthesis ; RNA, Messenger/genetics/metabolism

Cell Line ; Humans ; Liver ; metabolism ; Membrane Potential, Mitochondrial ; Mitochondria, Liver ; metabolism ; Proliferating Cell Nuclear Antigen ; biosynthesis ; Proteins ; pharmacology

To investigate the expressions of c-IAP2 and Smac in leukemia and their prognostic significance in adult patients with acute leukemia (AL), the mRNA expressions of c-IAP2 and Smac in 103 AL adult patients were measured by semi-quantity reverse transcription polymers chain reaction (RT-PCR). Other 20 adults were selected as normal controls (NC), K562 and Kg-1alpha cell lines were employed as positive control. The results showed that the expressions of c-IAP2 and Smac in de novo AL patients were higher than those in NC, while they decreased in patients at complete remission (CR). In relapsed patients, the expressions of c-IAP2 and Smac increased again. The mRNA expression of c-IAP2 and Smac in CML-CP were higher than that of NC, but no statistical significance was found (P > 0.05). In AL patients, the CR rate of c-IAP2+ and Smac+ cases were lower than those of c-IAP2- and Smac- cases. It is concluded that overexpression of c-IAP1 and Smac may play a synergic role in the pathogenesis of AL, and there is a positive correlation beween them. The c-IAP2 and Smac expressions are associated with remission rate in AL, while the patients with high level of c-IAP2 or Smac have low remission rates. It seems that c-IAP2 and Smac serve as markers of poor prognosis in AL.
Acute Disease ; Biomarkers, Tumor ; Humans ; Inhibitor of Apoptosis Proteins ; biosynthesis ; genetics ; Intracellular Signaling Peptides and Proteins ; genetics ; Leukemia ; metabolism ; Mitochondrial Proteins ; biosynthesis ; genetics ; Prognosis ; RNA, Messenger ; biosynthesis ; genetics ; Reverse Transcriptase Polymerase Chain Reaction

To investigate the expression and significance of X-linked inhibitor of apoptosis protein (XIAP) and XIAP-associated factor 1 (XAF1) in acute leukemia, the expression of XIAP, XAF1, Smac, and HtrA2 mRNA in the bone marrow aspirates from 87 newly diagnosed AL patients, 23 patients in remission, 6 patients in relapse, and 17 normal controls were detected by means of reverse transcriptase polymerase chain reaction (RT-PCR), and their relationship with clinical therapeutic efficiency was analyzed. The results showed that the expression level of XIAP mRNA in newly diagnosed AL patients (0.990 +/- 0.337) was significantly higher than that in normal controls (0.395 +/- 0.148) (P < 0.01); the positive rate and expression level of XAF1 mRNA in newly diagnosed AL patients (56.32%, 0.246 +/- 0.267) were significantly lower than that in normal controls (100%, 0.964 +/- 0.387) (P < 0.01). In 69 out of 87 newly diagnosed AL patients, efficacy remained evaluable. AL patients with high level of XIAP achieved a lower complete remission (CR) rate than patients with low level of XIAP (54.55% and 86.11%, respectively) (P < 0.01). XAF1 positive patients achieved a higher CR rate than XAF1 negative patients (86.84% and 51.61%, respectively) (P < 0.01). It is concluded that the overexpression of XIAP and negativity of XAF1 may be two adverse prognostic factors in AL patients.
Acute Disease ; High-Temperature Requirement A Serine Peptidase 2 ; Humans ; Inhibitor of Apoptosis Proteins ; biosynthesis ; genetics ; Intracellular Signaling Peptides and Proteins ; genetics ; Leukemia ; metabolism ; Mitochondrial Proteins ; biosynthesis ; genetics ; Neoplasm Proteins ; biosynthesis ; genetics ; Prognosis ; RNA, Messenger ; biosynthesis ; genetics ; Serine Endopeptidases ; biosynthesis ; genetics ; X-Linked Inhibitor of Apoptosis Protein ; biosynthesis ; genetics

Cardiotrophin-1 (CT-1) activates a distinct form of cardiac muscle cell hypertrophy in which the sarcomeric units are assembled in series. The aim of the study was to determine the expression pattern of sarcomeric contractile protein α-actin, specialized cytoskeletal protein α-actinin and mitochondrial uncoupling protein-2 (UCP2) in myocardial remodeling induced by chronic exposure to CT-1. Kunming mice were intraperitoneally injected with carboxy-terminal polypeptide (CP) of CT-1 (CT-1-CP, 500 μg·kg(-1)· day(-1)) for 1, 2, 3 and 4 week (s), respectively (4 groups obtained according to the injection time, n=10 each, with 5 males and 5 females in each group). Those injected with physiological saline for 4 weeks served as controls (n=10, with 5 males and 5 females). The heart tissues of mice were harvested at 1, 2, 3 or 4 week (s). Immunohistochemistry (IHC) and Western blotting (WB) were used to detect the distribution and expression of sarcomeric α-actin, α-actinin and mitochondrial UCP2 in myocardial tissues. IHC showed that α-actin was mainly distributed around the nuclei of cardiomyocytes, α-actinin concentrated around the striae and UCP2 scattered rather evenly in the plasma. The expression of α-actin was slightly greater than that of α-actinin and UCP2 in the control group (IHC: χ(2)=6.125; WB: F=0.249, P>0.05) and it gradually decreased after exposure to CT-1-CP. There was no significant difference in the expression of α-actin between the control group and the CT-1-CP-treated groups (χ (2)=7.386, P>0.05). But Western blotting revealed significant difference in the expression of α-actin between the control group and the 4-week CT-1-CP-treated group (F=2.912; q=4.203, P<0.05). Moreover, it was found that the expression of α-actinin increased stepwise with the exposure time in CT-1-CP-treated groups and differed significantly between CT-1-CP-treated groups and the control group (ICH: χ (2)=21.977; WB: F=50.388; P<0.01). The expression of UCP2 was initially increased (WB: control group vs. 1- or 2-week group, q values: 5.603 and 9.995, respectively, P<0.01) and then decreased (WB: control group vs. 3-week group, q=4.742, P<0.01; control group vs. 4-week group, q=0.558, P>0.05). It was suggested that long-term exposure to CT-1-CP could lead to the alteration in the expression of sarcomeric α-actin, α-actinin and mitochondrial UCP2. The different expressions of sarcomeric structure proteins and mitochondrial UCP2 may be involved in myocardial remodeling.
Actinin ; biosynthesis ; Actins ; biosynthesis ; Animals ; Cardiomegaly ; chemically induced ; metabolism ; pathology ; Cytokines ; adverse effects ; pharmacology ; Female ; Gene Expression Regulation ; drug effects ; Ion Channels ; biosynthesis ; Male ; Mice ; Mitochondrial Proteins ; biosynthesis ; Myocardium ; metabolism ; pathology ; Sarcomeres ; metabolism ; pathology ; Uncoupling Protein 2