ABSTRACT
The antiapoptotic protein Mcl-1, which is an attractive target for cancer treatment, is degraded under nutrient deprivation conditions in different types of cancer. This process sensitizes cancer cells to chemotherapy. It has been found that nutrient deprivation leads to suppression of Mcl-1 synthesis; however, the mechanisms of Mcl-1 degradation under such conditions remain to be elucidated. In this study, we have investigated the contribution of autophagy and proteasomal degradation to the regulation of the level of Mcl-1 protein under nutrient deprivation conditions. We found that these circumstances cause a decrease in the level of Mcl-1 in cancer cells in a macroautophagy-independent manner via proteasomal degradation.
Subject(s)
Apoptosis , Autophagy , Myeloid Cell Leukemia Sequence 1 Protein/metabolism , Neoplasms/metabolism , Nutrients/deficiency , Cell Line, Tumor , Humans , ProteolysisABSTRACT
BNIP3 is a member of Bcl-2 protein family involved in regulation of various forms of cell death. However, its role in these processes remains unclear and varies depending on the type of cancer cells and environmental factors (pH, O2 level, etc.). Here, the role of BNIP3 in apoptosis regulation in lung adenocarcinoma cells was investigated. The suppressed expression of BNIP3 caused inhibition of oxygen consumption and stimulated production of the mitochondrial reactive oxygen species, suggesting the role of BNIP3 in induction of mitochondrial dysfunction and its potential involvement in regulation of cell death. Indeed, cytochrome c release in the cells with BNIP3 knockout and knockdown was higher than in the wild-type (WT) upon apoptosis stimulation by cisplatin. Moreover, suppression of BNIP3 expression led to the increase in the caspase-3 activity and, as a consequence, accumulation of the apoptotic marker - p89 fragment of poly(ADP-ribose)-polymerase (PARP) - as compared to WT cells. Analysis of the SubG1 population by flow cytometry confirmed the elevated level of apoptosis in the BNIP3 knockout cells. Pretreatment with the antioxidant Trolox did not affect cell death, indicating that it was independent on reactive oxygen species. These data show that BNIP3 is involved in maintaining normal functioning of mitochondria and, as a result, can regulate the mitochondrial pathway of cell death.
Subject(s)
Adenocarcinoma of Lung/metabolism , Apoptosis , Lung Neoplasms/metabolism , Membrane Proteins/metabolism , Proto-Oncogene Proteins/metabolism , A549 Cells , Caspase 3/metabolism , Cisplatin/pharmacology , Cytochromes c/metabolism , Humans , Mitochondria/metabolism , Oxygen/metabolism , Reactive Oxygen Species/metabolismABSTRACT
The characteristics of the formation of the superoxide radical anion ([Formula: see text]) and hydrogen peroxide by xanthine oxidases isolated from microorganisms and from cow's milk were investigated. The increase in pH led to an increase in the rate of xanthine oxidation with oxygen by both xanthine oxidases. The functioning of xanthine oxidase from milk along with the two-electron reduction of O2 to H2O2 carries through the one-electron reduction of O2 to [Formula: see text], and the rate and the fraction of generation of [Formula: see text] increased with increasing pH. Under operation of the microbial xanthine oxidase, the [Formula: see text] radical was not detected in the medium. The results suggest a difference in the operation of active centers of enzyme from different sources.
Subject(s)
Escherichia coli Proteins/chemistry , Escherichia coli , Milk Proteins/chemistry , Milk , Xanthine Oxidase/chemistry , Animals , Cattle , Escherichia coli/enzymology , Escherichia coli/isolation & purification , Milk/enzymology , Milk/microbiologySubject(s)
Antiviral Agents , Neuraminidase/metabolism , Orthomyxoviridae , Virulence , Animals , Mice , Orthomyxoviridae/enzymologySubject(s)
Bird Diseases/microbiology , Orthomyxoviridae/pathogenicity , Animals , Bird Diseases/epidemiology , Chickens , Culture Techniques , Czechoslovakia , Ducks , England , Mice , Orthomyxoviridae Infections/epidemiology , Orthomyxoviridae Infections/microbiology , Scotland , Siberia , South Africa , Virus CultivationSubject(s)
Antibodies/analysis , Bird Diseases/epidemiology , Orthomyxoviridae Infections/epidemiology , Animals , Bird Diseases/etiology , Bird Diseases/immunology , Hemagglutination Inhibition Tests , Orthomyxoviridae Infections/etiology , Orthomyxoviridae Infections/immunology , Orthomyxoviridae Infections/veterinary , Species SpecificitySubject(s)
Antibodies/analysis , Orthomyxoviridae/pathogenicity , Adolescent , Adult , Aged , Animals , Child , Child, Preschool , Complement Fixation Tests , Guinea Pigs , Hemagglutination Inhibition Tests , Humans , Infant , Mice , Middle Aged , SiberiaABSTRACT
A total of 394 sera from persons in different age-groups among the inhabitants of the Vladivostok area were studied by the haemagglutination-inhibition (HI) test for the presence of influenza antibodies. Each serum was examined against 12 antigens of influenza A virus of human (A0, A1, and 2 strains of A2) and animal (1 swine, 2 equine and 5 avian strains) origin. All the sera were collected 8-9 months after the outbreak of A2 influenza in 1965. Antibodies to some animal viruses were present: Swine/Iowa, Equi/2/Miami, Tern/South Africa and Chicken/Scotland strains; negative results were found to Equi/1/Prague, Duck/England and Duck/Czechoslovakia and fowl plague strains. The pattern of HI antibody distribution to animal strains showed an increase in the range in relation to age; the largest was found in the older age-group (70 years and over).The authors suggest that antibodies in the human sera to animal strains are not necessarily an indication of past infection with those strains.
