Autophagy is one of several hepatic metabolic processes in which starved cells are supplied with glucose, free fatty acids, and amino acids to produce energy and synthesize new macromolecules. Moreover, it regulates the quantity and quality of mitochondria and other organelles. As the liver is a vital metabolic organ, specific forms of autophagy are necessary for maintaining liver homeostasis. Protein, fat, and sugar are the three primary nutrients that can be altered by different metabolic liver diseases. Drugs that have an effect on autophagy can either promote or inhibit autophagy, and as a result, it can either increase or inhibit the three major nutritional metabolisms that are affected by liver disease. Thus, this opens up a novel therapeutic option for liver disease.
Humans ; Liver/metabolism* ; Liver Diseases ; Autophagy ; Metabolic Diseases ; Mitochondria

Cadmium/metabolism* ; Kidney ; Cells, Cultured ; Mitochondria ; Metallothionein/metabolism* ; Liver

Animals ; Endoplasmic Reticulum ; metabolism ; Fatty Liver ; metabolism ; pathology ; Humans ; Mitochondria ; metabolism ; Non-alcoholic Fatty Liver Disease

Liver plays a central role in the biogenesis of major metabolites including glucose, fatty acids, and cholesterol. Increased incidence of obesity in the modern society promotes insulin resistance in the peripheral tissues in humans, and could cause severe metabolic disorders by inducing accumulation of lipid in the liver, resulting in the progression of non-alcoholic fatty liver disease (NAFLD). NAFLD, which is characterized by increased fat depots in the liver, could precede more severe diseases such as non-alcoholic steatohepatitis (NASH), cirrhosis, and in some cases hepatocellular carcinoma. Accumulation of lipid in the liver can be traced by increased uptake of free fatty acids into the liver, impaired fatty acid beta oxidation, or the increased incidence of de novo lipogenesis. In this review, I would like to focus on the roles of individual pathways that contribute to the hepatic steatosis as a precursor for the NAFLD.
Acetyl Coenzyme A/metabolism ; Fatty Acids/metabolism ; Fatty Liver/*metabolism/pathology ; Humans ; Lipogenesis ; Mitochondria/metabolism ; Triglycerides/metabolism

The effects of 7-ethyl-8-methylf1avin (7-Et) and 7-methyl-8-ethyl-flavin (8-Et) on rat hepatic monoamine oxidase (MAO), brain MAO activity and 5-hydroxytryptamine (5-HT or serotonin) in rat brain were investigated. In the study of hepatic MAO activity, kynur-amine a nonphysiological substrate for both A and B type MAO, was used for a spectro-photometric method, and [14C]-labeled amines were also used for a radiometric procedure for camparison with MAO activity determined by the spectrophotometric method. The rate of change in MAO activity of hepatic mitochondria from rats receiving Rb-def and 7-Et and 8-Et flavin showed the activity was severely reduced during 8 weeks. Rapid reduction of enzyme activity (50% in def-group, 35% in 7-Et group and 8% 8-Et flavin group) was observed at the end of 2 weeks. The enzyme activity lasted with slow decre-ment of enzyme level from 4 weeks to the end of 8 weeks as low as 16% in def, 18% in 7-Et and 3% in 8-Et flavin group. The trend of decrement of MAO activity when kynura-mine was used as a substrate appears to be similar with the small variation of MAO activity when [14C]-labelled tyramine, dopamine, serotonin and tryptamine respectively were used as substrate. The rate of decay of brain mitochondrial MAO activity in rats receiving each respective f1avin was not rapid and severely depressed as the MAO activity we have found in liver mitochondrial MAO of rats during the 8 week experimental time, but a similar tendency of decay of MAO in each group was observed. The potent inhibitory effect of 8-Et on brain MAO was confirmed by the study of the simultaneous measure-ment of MAO activity in each experimental group. when the reduction Of brain MAO activity in rats receiving 8-Et after 6 weeks was approximately 80% of normal and in the same rats the concentration of brain 5-HT showed a 60% increment of that of the normal mts. During the experimental period there is no absolute parallelism between the MAO inhibition and 5-HT increase. However when the reduction of MAO activity reached 80% of normal value, the concentration of 5-HT increased dramatically as much as 60% of normal value. The results so far suggest clearly that 8-Et produces a much more potent inhibitory effect on the hepatic MAO a s well as brain MAO in rats. Therefore our present and previous results suggest that 7-Et and 8-Et flavin should bind itself to hepatic, brain MAO apoenzyme in the condition of total absence of riboflavin in these animals, and the holenzyme is catalytically inactive.
Animal ; Brain/enzymology* ; Brain/metabolism ; Comparative Study ; Male ; Mitochondria/enzymology* ; Mitochondria, Liver/enzymology* ; Monoamine Oxidase/metabolism* ; Rats ; Serotonin/metabolism*

OBJECTIVETo investigate the abundance of metabolic proteins in adult and fetal human livers.

METHODSAdult liver homogenate proteins, fetal liver homogenate proteins, adult liver mitochondrial proteins and fetal liver mitochondrial proteins were obtained from fetal or adult liver tissues and examined using the antibody microarrays containing 19 liver monoclonal mitochondrial antibodies. The protein expression abundances were compared among the 4 protein fractions and the pathways related to protein metabolisms were explored.

RESULTSIn adult liver mitochondria, aldehyde oxidase and carbonyl reductase were up-regulated by 2.6 and 1.7 folds, respectively, whereas corticosteroid 11-beta-dehydrogenase isozyme 1, epoxide hydrolase 1 and fibrinogen beta chain protein were down-regulated by 1.7, 1.9 and 2.2 folds, respectively, compared to those in fetal liver mitochondria. The abundance of epoxide hydrolase 1 and glutathione transferase omega-1 was significantly different between adult and fetal liver homogenate samples.

CONCLUSIONOur results demonstrate a clear difference in the expression profiles of metabolic proteins in the liver between adults and human fetuses to allow a better understanding of the occurrence and development of the metabolic proteins and the identification of markers of liver metabolism.

Adult ; Antibodies ; genetics ; metabolism ; Fetus ; metabolism ; Humans ; Liver ; embryology ; metabolism ; Mitochondria, Liver ; metabolism ; Mitochondrial Proteins ; metabolism ; Protein Array Analysis

In order to elucidate mechanisms of Ca++ antagonistic action of kanamycin in the biological system, the effects of kanamycin on Ca++ transport in sarcoplasmic reticulum of rabbit skeletal muscle and liver mitochondria were studied. At the same time, the effect of the agent on Bowditch and Woodworth phenomena of rabbit heart as well as the superprecipitation of actomyosin isolated from rabbit skeletal muscle were studied. Since kanamycin inhibits the Bowditch staircase phenomena in rabbit cardiac muscle, it is speculated that kanamycin inhibits Ca++ influx across the cell membrane which is required for the muscular contraction. Kanamycin also inhibits the Woodworth staircase phenomena, indicating a decrease in size of the Ca++ pool in cardiac muscle which may be brought about by an inhibition of Ca++ transport in sarcoplasmic reticulum and mitochondria. Actually, kanamycin was found to inhibit both the activities of Ca++ activated adenosine triphosphatases (ATPase) and Ca++ transport in sarcoplasmic reticulum and mitochondria. Kanamycin also inhibits both the development of superprecipitation and the activity of Ca++activated ATPase of skeletal actomyosin in rabbits. From the results obtained above, it may be concluded that kanamycin possesses a Ca++ antagonistic action in the biological system.
Animal ; Calcium/antagonists & inhibitors* ; Kanamycin/pharmacology* ; Mitochondria, Liver/metabolism ; Muscles/metabolism ; Myocardium/metabolism ; Rabbits

OBJECTIVETo investigate the opening of the mitochondrial permeability transition pores of the cultured hepatocytes in a non-alcoholic fatty liver disease model and its relationship with apoptosis of the cells.

METHODSOleic acid was used to induce cultured L02 hepatocyte steatotic in making a model of NAFLD. The steatotic hepatocytes were detected with oil red O staining; the opening of the mitochondrial permeability transition pores was observed under a fluorescence microscope. The apoptosis of the cells was detected with a flow cytometer.

RESULTSAfter adding oleic acid to the cultured hepatocytes, a model of steatosis of human hepatocytes was established after 24 hours. Oleic acid opened the mitochondrial permeability transition pores of the L02 hepatocytes (72.58%+/-2.78%) more than that in the control group (8.28%+/-4.98%) and the difference was statistically significant (P < 0.01). Apoptosis index of the steatotic hepatocytes at 24 hours and 48 hours were 11.09%+/-4.95% and 15.24%+/-2.45%. They were also higher than those of the control group (4.56%+/-1.25%) (P < 0.05, P < 0.01).

CONCLUSIONOpening the mitochondrial permeability transition pores may be the basis of the apoptosis of steatotic hepatocytes in vitro, and it also may be related to the steatosis of NAFLD in human beings.

Apoptosis ; Cell Line ; Fatty Liver ; metabolism ; pathology ; Hepatocytes ; metabolism ; Humans ; Mitochondria, Liver ; metabolism ; Mitochondrial Membrane Transport Proteins ; metabolism

Animals ; Endotoxemia ; metabolism ; pathology ; Female ; Liver ; metabolism ; pathology ; Male ; Mitochondria, Liver ; metabolism ; Rats ; Reactive Oxygen Species ; metabolism

Apoptosis ; Humans ; Liver Failure, Acute ; metabolism ; pathology ; Mitochondria ; metabolism ; pathology ; Oxidative Stress