Leptin expression in human primary skeletal muscle cells is reduced during differentiation.
We found leptin to be strongly expressed in undifferentiated human myoblasts derived from biopsies of the thigh (Musculus vastus lateralis). Both mRNA expression and secretion of leptin were reduced during in vitro differentiation into primary myotubes. However, the expression of the leptin receptor (OB-Rb) mRNA, was unchanged during differentiation of the muscle cells. Administration of recombinant leptin had no effect on leptin, myogenin, myoD, or GLUT4 mRNA expressions during the period of cellular differentiation. A functional leptin receptor was demonstrated by an acute leptin-induced 1.5-fold increase in ERK activity (P = 0.029). Although mRNA expression of regulation of suppressor of cytokine signaling-3 (SOCS-3) mRNA expression was unaltered, leptin significantly stimulated fatty acid oxidation after 6 h measured as acid soluble metabolites (ASM). Palmitic acid (PA), oleic acid (OA), and eicosapentaenoic acid (EPA), known to modulate leptin expression in other tissues, had no effect on mRNA expression or secretion of leptin from human myotubes. In conclusion, we demonstrate that leptin is highly expressed in undifferentiated human myoblasts and the expression is reduced during differentiation to mature myotubes. The role of leptin in these cells needs to be further characterized.
Solberg
Rigmor
R
Department of Pharmacology, School of Pharmacy, University of Oslo, Oslo, Norway.
Aas
Vigdis
V
Thoresen
G Hege
GH
Kase
Eili Tranheim
ET
Drevon
Christian A
CA
Rustan
Arild C
AC
Reseland
Janne E
JE
D002454:Cell Differentiation / Q000502:physiology*; D002478:Cells, Cultured; D005227:Fatty Acids / Q000502:physiology; D005947:Glucose / Q000502:physiology; D006801:Humans; D020738:Leptin / Q000096:biosynthesis / Q000235:genetics*; D032342:Muscle Cells / Q000378:metabolism*; D018485:Muscle Fibers, Skeletal / Q000166:cytology / Q000378:metabolism; D018482:Muscle, Skeletal / Q000166:cytology / Q000378:metabolism*; D032446:Myoblasts / Q000166:cytology / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D054411:Receptors, Leptin / Q000096:biosynthesis / Q000235:genetics; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism
D005227:Fatty Acids; D020738:Leptin; D012333:RNA, Messenger; D054411:Receptors, Leptin; D011994:Recombinant Proteins; D005947:Glucose