Ghrelin and des-acyl ghrelin promote differentiation and fusion of C2C12 skeletal muscle cells.
Ghrelin is an acylated peptidyl gastric hormone acting on the pituitary and hypothalamus to stimulate appetite, adiposity, and growth hormone release, through activation of growth hormone secretagogue receptor (GHSR)-1a receptor. Moreover, ghrelin features several activities such as inhibition of apoptosis, regulation of differentiation, and stimulation or inhibition of proliferation of several cell types. Ghrelin acylation is absolutely required for both GHSR-1a binding and its central endocrine activities. However, the unacylated ghrelin form, des-acyl ghrelin, which does not bind GHSR-1a and is devoid of any endocrine activity, is far more abundant than ghrelin in plasma, and it shares with ghrelin some of its cellular activities. In here we show that both ghrelin and des-acyl ghrelin stimulate proliferating C2C12 skeletal myoblasts to differentiate and to fuse into multinucleated myotubes in vitro through activation of p38. Consistently, both ghrelin and des-acyl ghrelin inhibit C2C12 proliferation in growth medium. Moreover, the ectopic expression of ghrelin in C2C12 enhances differentiation and fusion of these myoblasts in differentiation medium. Finally, we show that C2C12 cells do not express GHSR-1a, but they do contain a common high-affinity binding site recognized by both acylated and des-acylated ghrelin, suggesting that the described activities on C2C12 are likely mediated by this novel, yet unidentified receptor for both ghrelin forms.
Filigheddu
Nicoletta
N
Department of Medical Sciences, University of Piemonte Orientale, 28100 Novara, Italy. nicoletta.filigheddu@med.unipmn.it
Gnocchi
Viola F
VF
Coscia
Marco
M
Cappelli
Miriam
M
Porporato
Paolo E
PE
Taulli
Riccardo
R
Traini
Sara
S
Baldanzi
Gianluca
G
Chianale
Federica
F
Cutrupi
Santina
S
Arnoletti
Elisa
E
Ghè
Corrado
C
Fubini
Alberto
A
Surico
Nicola
N
Sinigaglia
Fabiola
F
Ponzetto
Carola
C
Muccioli
Giampiero
G
Crepaldi
Tiziana
T
Graziani
Andrea
A
D000818:Animals; D001665:Binding Sites / Q000187:drug effects; D015415:Biomarkers; D002454:Cell Differentiation / Q000187:drug effects*; D002459:Cell Fusion; D049109:Cell Proliferation / Q000187:drug effects; D003470:Culture Media; D004247:DNA / Q000096:biosynthesis; D004789:Enzyme Activation / Q000187:drug effects; D005786:Gene Expression Regulation / Q000187:drug effects; D054439:Ghrelin; D051379:Mice; D018485:Muscle Fibers, Skeletal / Q000187:drug effects; D018482:Muscle, Skeletal / Q000166:cytology* / Q000187:drug effects*; D036361:Peptide Hormones / Q000494:pharmacology*; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D043562:Receptors, G-Protein-Coupled / Q000235:genetics / Q000378:metabolism; D054440:Receptors, Ghrelin; D048051:p38 Mitogen-Activated Protein Kinases / Q000378:metabolism
D015415:Biomarkers; D003470:Culture Media; D054439:Ghrelin; D036361:Peptide Hormones; D012333:RNA, Messenger; D043562:Receptors, G-Protein-Coupled; D054440:Receptors, Ghrelin; C422650:ghrelin, des-n-octanoyl; D004247:DNA; D048051:p38 Mitogen-Activated Protein Kinases