Temperature and serine phosphorylation regulate glycerol-3-phosphate dehydrogenase in skeletal muscle of hibernating Richardson’s ground squirrels

2019 ◽  
Vol 97 (2) ◽  
pp. 148-157
Author(s):  
Anthony A. Ruberto ◽  
Samantha M. Logan ◽  
Kenneth B. Storey
Keyword(s):  
Skeletal Muscle ◽  
Guanidine Hydrochloride ◽  
Ground Squirrels ◽  
Serine Phosphorylation ◽  
Dihydroxyacetone Phosphate ◽  
Kinetic Properties ◽  
Triglyceride Hydrolysis ◽  
Endogenous Protein ◽  
Triglyceride Biosynthesis ◽  
Glycerol 3 Phosphate Dehydrogenase

Glycerol-3-phosphate dehydrogenase (G3PDH) bridges carbohydrate and lipid metabolism by interconverting glycerol-3-phosphate (G3P) and dihydroxyacetone phosphate (DHAP). This reversible reaction converts G3P derived from triglyceride hydrolysis to DHAP that can then enter glycolysis or gluconeogenesis and, in the reverse reaction, makes G3P for use in triglyceride biosynthesis. Small hibernating mammals rely almost exclusively on triglyceride reserves as their fuel for energy production during torpor and the recovery of glycerol after lipolysis is an important source of carbohydrate over the nonfeeding winter months. G3PDH (∼37 kDa) was purified from skeletal muscle of euthermic and hibernating Richardson’s ground squirrels (Urocitellus richardsonii) using three column chromatography steps. Analysis of enzyme kinetic properties revealed that G3PDH from hibernator muscle had higher affinities for G3P and NAD at low (5 °C) assay temperature compared with high (21 or 37 °C) and a greater stability in the presence of denaturing agents (urea, guanidine hydrochloride) or high temperature (50 °C). Immunoblotting showed that hibernator muscle G3PDH had a higher phosphoserine content than the enzyme from euthermic controls and incubation studies showed that enzyme affinity for G3P changed significantly by stimulating endogenous protein kinases or phosphatases. Overall, this study suggests that the properties of ground squirrel muscle G3PDH are modulated by temperature and post-translational phosphorylation to alter enzyme function under euthermic versus hibernating states.

scholarly journals Mitochondrial glycerol 3‐phosphate dehydrogenase promotes skeletal muscle regeneration

2018 ◽  
Vol 10 (12) ◽  
Author(s):  
Xiufei Liu ◽  
Hua Qu ◽  
Yi Zheng ◽  
Qian Liao ◽  
Linlin Zhang ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Muscle Regeneration ◽  
Skeletal Muscle Regeneration ◽  
Glycerol 3 Phosphate Dehydrogenase

Posttranslational modifications of recombinant myotube-synthesized human factor IX

Blood ◽  
2001 ◽  
Vol 97 (1) ◽  
pp. 130-138 ◽  
Author(s):  
Valder R. Arruda ◽  
James N. Hagstrom ◽  
Jeffrey Deitch ◽  
Terry Heiman-Patterson ◽  
Rodney M. Camire ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Posttranslational Modifications ◽  
Half Life ◽  
Specific Activity ◽  
Factor Ix ◽  
Serine Phosphorylation ◽  
Hemophilia B ◽  
Tyrosine Sulfation ◽  
Aav Vector ◽  
Carbohydrate Analysis

Abstract Recent data demonstrate that the introduction into skeletal muscle of an adeno-associated viral (AAV) vector expressing blood coagulation factor IX (F.IX) can result in long-term expression of the transgene product and amelioration of the bleeding diathesis in animals with hemophilia B. These data suggest that biologically active F.IX can be synthesized in skeletal muscle. Factor IX undergoes extensive posttranslational modifications in the liver, the normal site of synthesis. In addition to affecting specific activity, these posttranslational modifications can also affect recovery, half-life in the circulation, and the immunogenicity of the protein. Before initiating a human trial of an AAV-mediated, muscle-directed approach for treating hemophilia B, a detailed biochemical analysis of F.IX synthesized in skeletal muscle was carried out. As a model system, human myotubes transduced with an AAV vector expressing F.IX was used. F.IX was purified from conditioned medium using a novel strategy designed to purify material representative of all species of rF.IX in the medium. Purified F.IX was analyzed by sodium dodecyl sulfate–polyacrylamide gel electrophoresis (SDS-PAGE), N-terminal sequence analysis, chemical γ-carboxyglutamyl analysis, carbohydrate analysis, assays for tyrosine sulfation, and serine phosphorylation, and for specific activity. Results show that myotube-synthesized F.IX has specific activity similar to that of liver-synthesized F.IX. Posttranslational modifications critical for specific activity, including removal of the signal sequence and propeptide, and γ-carboxylation of the N-terminal glutamic acid residues, are also similar, but carbohydrate analysis and assessment of tyrosine sulfation and serine phosphorylation disclose differences. In vivo experiments in mice showed that these differences affect recovery but not half-life of muscle-synthesized F.IX.

scholarly journals Influence of rapid changes in cytosolic pH on oxidative phosphorylation in skeletal muscle: theoretical studies

2002 ◽  
Vol 365 (1) ◽  
pp. 249-258 ◽  
Author(s):  
Bernard KORZENIEWSKI ◽  
Jerzy A. ZOLADZ
Keyword(s):  
Skeletal Muscle ◽  
Creatine Kinase ◽  
Oxidative Phosphorylation ◽  
Kinetic Properties ◽  
Main Role ◽  
Anaerobic Glycolysis ◽  
Cytosolic Ph ◽  
Intensive Exercise ◽  
Proton Production ◽  
The Stability

Cytosolic pH in skeletal muscle may vary significantly because of proton production/consumption by creatine kinase and/or proton production by anaerobic glycolysis. A computer model of oxidative phosphorylation in intact skeletal muscle developed previously was used to study the kinetic effect of these variations on the oxidative phosphorylation system. Two kinds of influence were analysed: (i) via the change in pH across the inner mitochondrial membrane and (ii) via the shift in the equilibrium of the creatine kinase-catalysed reaction. Our simulations suggest that cytosolic pH has essentially no impact on the steady-state fluxes and most metabolite concentrations. On the other hand, rapid acidification/alkalization of cytosol causes a transient decrease/increase in the respiration rate. Furthermore, changes in pH seem to affect significantly the kinetic properties of transition between resting state and active state. An increase in pH brought about by proton consumption by creatine kinase at the onset of exercise lengthens the transition time. At intensive exercise levels this pH increase could lead to loss of the stability of the system, if not compensated by glycolytic H+ production. Thus our theoretical results stress the importance of processes/mechanisms that buffer/compensate for changes in cytosolic proton concentration. In particular, we suggest that the second main role of anaerobic glycolysis, apart from additional ATP supply, may be maintaining the stability of the system at intensive exercise.

scholarly journals Myostatin levels in skeletal muscle of hibernating ground squirrels

2011 ◽  
Vol 214 (15) ◽  
pp. 2522-2527 ◽  
Author(s):  
N. E. Brooks ◽  
K. H. Myburgh ◽  
K. B. Storey
Keyword(s):  
Skeletal Muscle ◽  
Ground Squirrels

scholarly journals Nitrogen recycling buffers against ammonia toxicity from skeletal muscle breakdown in hibernating arctic ground squirrels

2020 ◽  
Vol 2 (12) ◽  
pp. 1459-1471
Author(s):  
Sarah A. Rice ◽  
Gabriella A. M. Ten Have ◽  
Julie A. Reisz ◽  
Sarah Gehrke ◽  
Davide Stefanoni ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Ground Squirrels ◽  
Ammonia Toxicity ◽  
Nitrogen Recycling ◽  
Muscle Breakdown ◽  
Arctic Ground Squirrels
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