Carboxy-terminal fragment of osteogenic growth peptide regulates myeloid differentiation through RhoA.
The carboxy-terminal fragment of osteogenic growth peptide, OGP(10-14), is a pentapeptide with bone anabolic effects and hematopoietic activity. The latter activity appears to be largely enhanced by specific growth factors. To study the direct activity of OGP(10-14) on myeloid cells, we tested the pentapeptide proliferating/differentiating effects in HL60 cell line. In this cell line, OGP(10-14) significantly inhibited cell proliferation, and enhanced myeloperoxidase (MPO) activity and nitroblue tetrazolium reducing ability. Moreover, it induced cytoskeleton remodeling and small GTP-binding protein RhoA activation. RhoA, which is known to be involved in HL60 differentiation, mediated these effects as shown by using its specific inhibitor, C3. Treatment with GM-CSF had a comparable OGP(10-14) activity on proliferation, MPO expression, and RhoA activation. Further studies on cell proliferation and RhoA activation proved enhanced activity by association of the two factors. These results strongly suggest that OGP(10-14) acts directly on HL60 cells by activating RhoA signaling although other possibilities cannot be ruled out.
Department of Human Morphology and Applied Biology, Section of Histology and General Embryology, University of Pisa, Via Roma, Pisa, Italy.
Letizia
L
Mattii
Rita
R
Fazzi
Stefania
S
Moscato
Cristina
C
Segnani
Simone
S
Pacini
Sara
S
Galimberti
Delfo
D
D'Alessandro
Nunzia
N
Bernardini
Mario
M
Petrini
D000199:Actins / Q000378:metabolism; D002454:Cell Differentiation / Q000187:drug effects*; D049109:Cell Proliferation / Q000187:drug effects; D018922:HL-60 Cells; D006657:Histones; D006801:Humans; D036341:Intercellular Signaling Peptides and Proteins / Q000494:pharmacology*; D022423:Myeloid Cells / Q000166:cytology / Q000187:drug effects*; D009580:Nitroblue Tetrazolium; D009195:Peroxidase / Q000378:metabolism; D020742:rhoA GTP-Binding Protein / Q000378:metabolism*
D000199:Actins; D006657:Histones; D036341:Intercellular Signaling Peptides and Proteins; C074533:osteogenic growth peptide; D009580:Nitroblue Tetrazolium; D009195:Peroxidase; D020742:rhoA GTP-Binding Protein