Muscle Pyruvate Kinase Activity Research Articles

Abstract 3380: Cancer usurps skeletal muscle as an energy repository

Abstract Cancer cells produce energy through aerobic glycolysis, but contributions of host tissues to cancer energy metabolism is unclear. In this study, we aimed to elucidate the cancer-host energy production relationship, in particular, between cancer energy production and host muscle. During the development and progression of colorectal cancer (CRC), expression of the secreted autophagy-inducing stress protein HMGB1 increased in the muscle of tumor-bearing animals. This effect was associated with decreased expression of pyruvate kinase PKM1 and pyruvate kinase activity in muscle via the HMGB1 receptor RAGE. However, muscle mitochondrial energy production was maintained. In contrast, HMGB1 addition to CRC cells increased lactate fermentation. In the muscle, HMGB1 addition induced autophagy by decreasing levels of active mTOR and increasing autophagy-associated proteins, plasma glutamate and 13C-glutamine incorporation into acetyl-CoA. In a mouse model of colon carcinogenesis, a temporal increase in HMGB1 occurred in serum and colonic mucosa with an increase in autophagy associated with altered plasma free amino acids levels, increased glutamine and decreased PKM1 levels. These differences were abolished by administration of an HMGB1 neutralizing antibody. Similar results were obtained in a mouse xenograft model of human CRC. Taken together, our findings suggest that HMGB1 released during tumorigenesis recruits muscle to supply glutamine to cancer cells as an energy source. Citation Format: Yi Luo, Junya Yoneda, Hitoshi Ohmori, Takamitsu Sasaki, Hiroki Kuniyasu. Cancer usurps skeletal muscle as an energy repository. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 3380. doi:10.1158/1538-7445.AM2014-3380

Effects of Glyphosate on Growth Rate, Metabolic Rate and Energy Reserves of Early Juvenile Crayfish, Cherax quadricarinatus M.

Early juveniles of the crayfish Cherax quadricarinatus were exposed for 60 days to 10 and 40 mg/L of pure glyphosate (acid form) in freshwater. Mortality was 33 % at the highest concentration, while no differences in molting were noted among treatments. After the first month of exposure, weight gain was significantly (p < 0.05) reduced in the 40 mg/L group. At the end of the assay, lipid levels in muscle, as well as protein level in both hepatopancreas and muscle were significantly (p < 0.05) reduced. These results suggest long-term utilization of both lipid and protein as main energetic reserves, likely in response to the chronic stress associated with herbicide exposure. Besides, the lower pyruvate kinase activity in muscle suggests a possible metabolic depression in this tissue. The hemolymphatic ASAT:ALAT ratio showed higher levels than the control at the highest glyphosate concentration, indicating possible damage to several tissues.

Cancer Usurps Skeletal Muscle as an Energy Repository

Cancer cells produce energy through aerobic glycolysis, but contributions of host tissues to cancer energy metabolism are unclear. In this study, we aimed to elucidate the cancer-host energy production relationship, in particular, between cancer energy production and host muscle. During the development and progression of colorectal cancer, expression of the secreted autophagy-inducing stress protein HMGB1 increased in the muscle of tumor-bearing animals. This effect was associated with decreased expression of pyruvate kinase PKM1 and pyruvate kinase activity in muscle via the HMGB1 receptor for advanced glycation endproducts (RAGE). However, muscle mitochondrial energy production was maintained. In contrast, HMGB1 addition to colorectal cancer cells increased lactate fermentation. In the muscle, HMGB1 addition induced autophagy by decreasing levels of active mTOR and increasing autophagy-associated proteins, plasma glutamate, and (13)C-glutamine incorporation into acetyl-CoA. In a mouse model of colon carcinogenesis, a temporal increase in HMGB1 occurred in serum and colonic mucosa with an increase in autophagy associated with altered plasma free amino acid levels, increased glutamine, and decreased PKM1 levels. These differences were abolished by administration of an HMGB1 neutralizing antibody. Similar results were obtained in a mouse xenograft model of human colorectal cancer. Taken together, our findings suggest that HMGB1 released during tumorigenesis recruits muscle to supply glutamine to cancer cells as an energy source.

Carbohydrate metabolism in temporal and persistent hypoglycemic chickens induced by insulin infusion.

In order to elucidate the regulatory mechanism of blood glucose concentrations specific to chickens, carbohydrate metabolism in the liver, muscle and kidney and metabolite concentrations in the blood were investigated in chickens with acute and persistent hypoglycemia. Acute and persistent hypoglycemia were experimentally induced by a single injection of insulin (8 U/kg BW) or by continuous infusion of insulin (22.5 U/kg BW/day) for 4 days. Non-esterified fatty acid (NEFA) concentration in plasma and D-3-hydroxybutyrate (3HB) concentrations in liver and muscle increased in the acute hypoglycemia. Plasma NEFA concentration and 3HB concentration in the blood and liver were not changed at day 3 of persistent hypoglycemia, while 3HB concentration in the muscle was decreased. Phosphofructokinase (PFK) activity in the liver tended to increase but PFK and pyruvate kinase (PK) activities were unchanged in acute hypoglycemia. In persistent hypoglycemia, increase of hepatic PFK activity at day 1 in which it was reversed at day 3, and a small increase of muscle PK activity were observed, while PK and phosphoenolpyruvate carboxykinase (PEPCK) activities in the liver and kidney were not significantly changed. These results show that in the persistent hypoglycemic chickens, hepatic glycolysis transiently increases, which is followed by a small decrease, while glycolysis in muscles and gluconeogenesis in the liver and kidney are not significantly changed.

Pyruvate Kinase Activity as an Indicator of Temperature Attained During Cooking of Cured Pork

Muscle pyruvate kinase (PYK) activity was established as a biochemical indicator of temperature attained during cooking in both a model system and a commercial-type pullman-style canned cured pork product. Water extract (model system) or pressed-out meat juice (commercial-type pullman-style canned cured pork) was incubated (37°C up to 40 min) with reagent containing adenosine diphosphate, phosphoenolpyruvic acid and NADH. Lactate dehydrogenase (LDH) necessary for the reaction is provided by the muscle extract or meat juice. When muscle PYK activity is present, NADH is oxidized resulting in a loss of fluorescence (reaction mixture spots on filter paper viewed under long-wave ultraviolet light). Model system results showed high PYK activity (no fluorescence) remained in samples heated to 67.7°C. PYK activity progressively declined in samples heated to 68.3°C and 68.9°C. No PYK activity was detected in samples heated to 69.5°C or 70°C. Canned product attaining a core temperature of 62.9°C had high PYK activity. PYK activity progressively declined in product heated to 65.6°C and 68.6°C. Essentially no PYK activity was detected from product processed to 69.9°C.

Dual effects of phenylalanine analogs on rabbit-muscle pyruvate kinase activity.

Rabbit muscle pyruvate kinase activity has been studied in the presence of L-phenylalanine and its analogs: L-phenylalanyl methyl ester (PheOMe), L-1-amino-2-phenylethyl phosphonic acid (PnPhe), L-alanine and L-1-aminoethyl phosphonic acid (PnAla). At appropriate pH and substrate concentrations all the analogs and Phe exhibited activatory and inhibitory effects at low (1--5 mM) and at high (above 5mM) ligand concentrations respectively. Activation of pyruvate kinase by Phe and PheOMe was observed at pH above 8.2 in the presence of 2.5 mM ADP and 0.5 mM phosphoenolpyruvate (P-pyruvate), while PnPhe activation was also observed at pH 7.5. The activatory effect followed the order: PnPhe much greater than Phe greater than PheOMe. All the effectors showed a mixed type of inhibition or activation with P-pyruvate as a variable substrate and a non-competitive inhibition or activation with ADP as a variable substrate.

Ribonucleoprotein complexes of pyruvate kinase from human skeletal muscle.

About 25% of total pyruvate kinase activity in muscle appears in a bound form which is insoluble in water or diluted salt solutions at pH 5.8. That activity is associated with the ribonuc-leoprotein complexes and is soluble at high ionic strength. A procedure is described for the purification and crystallization of this enzyme form herein called pyruvate kinase MB and water soluble form MA.