Involvement of a phosphorylation-mediated pathway to regulate the function of NSPL1 in exercise.
Skeletal-type neuroendocrine-specific protein like 1 (sk-NSPL1) has been demonstrated to be physiologically important in regulating the membrane translocation of glucose transporter 4 (GLUT4) in skeletal muscles. We investigated the levels of phosphorylation in proteins that are thought to be involved in exercise in wild-type and sk-NSPL1-deficient muscles with specific antibodies and phosphate-metal affinity chromatography resin (p-resin). In both normal skeletal muscle and sk-NSPL1-deficient muscle, adenosine monophosphate (AMP)-dependent kinase (AMPK) and acetyl-CoA carboxylase (ACC) were phosphorylated and adsorbed onto p-resin at high levels after exercise. On the other hand, the effect of 5-aminoimidazole-4-carboxyamide ribonucleoside (AICAR), which is an activator of AMPK, in blood glucose was greatly diminished in mutant mice. P-resin adsorbed sk-NSPL1 in the membrane fraction from wild-type muscle after exercise and AICAR administration. Isolated sk-NSPL1 from wild-type also had increased adsorption onto p-resin after treatment with Ca(2+) and adenosine triphosphate (ATP). After long-term incubation of sk-NSPL1-containing membrane without ATP, sk-NSPL1 adsorption onto anion-exchange resin was drastically reduced. These results suggest that the function of sk-NSPL1 is regulated by a [Ca(2+)](i)- and AMPK-mediated pathway under exercise, and support the hypothesis that sk-NSPL1 is an important factor in the downstream of the exercise-dependent pathway in GLUT4 translocation.
Functional Probe Research Laboratory, RIKEN Center for Molecular Imaging Science, Kobe 650–0047, Japan. tikemotoriko@riken.jp
Takaaki
T
Ikemoto
Masaaki
M
Suzuki
Hirotaka
H
Onoe
D055372:AMP-Activated Protein Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D000103:Acetyl-CoA Carboxylase / Q000378:metabolism*; D000620:Aminoimidazole Carboxamide / Q000031:analogs & derivatives / Q000494:pharmacology; D000818:Animals; D001786:Blood Glucose / Q000378:metabolism; D015153:Blotting, Western; D002852:Chromatography, Ion Exchange; D051275:Glucose Transporter Type 4 / Q000378:metabolism*; D066298:In Vitro Techniques; D008297:Male; D008565:Membrane Proteins / Q000378:metabolism*; D051379:Mice; D018345:Mice, Knockout; D009124:Muscle Proteins / Q000378:metabolism*; D018482:Muscle, Skeletal / Q000201:enzymology / Q000502:physiology*; D009419:Nerve Tissue Proteins / Q000378:metabolism*; D010766:Phosphorylation; D010805:Physical Conditioning, Animal / Q000502:physiology*; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D012265:Ribonucleotides / Q000494:pharmacology
D001786:Blood Glucose; D051275:Glucose Transporter Type 4; D008565:Membrane Proteins; D009124:Muscle Proteins; D009419:Nerve Tissue Proteins; D047428:Protein Kinase Inhibitors; D012265:Ribonucleotides; C484735:Rtn2 protein, mouse; C495693:Slc2a4 protein, mouse; D000620:Aminoimidazole Carboxamide; D055372:AMP-Activated Protein Kinases; D000103:Acetyl-CoA Carboxylase; C031143:AICA ribonucleotide