The small peptide OGP(10-14) acts through Src kinases and RhoA pathways in Mo-7e cells: morphologic and immunologic evaluation.
ABSTRACT Osteogenic growth peptide (OGP) is an endogenous tetradecapeptide present in micromolar concentrations in mammalian serum; its carboxy-terminal pentapeptide, OGP(10-14), represents its physiologically active fragment. OGP(10-14) induces proliferation and differentiation in fibroblast and osteoblast cell lines, and it enhances hematopoiesis in vitro and in vivo. The signaling pathways triggered by OGP(10-14) are not yet fully known. In the present report, we evaluated the effect of OGP(10-14) on differentiation of a cancer megakaryoblast cell line and its involvement on RhoA and Src family kinases signaling pathway.
Cell proliferation of the Mo-7e line was evaluated using the MTT test. Mo-7e differentiation was evaluated by microscopic observation of cell morphology and by expression of the factor VIII-related antigen. Involvement of RhoA and Src kinases on signaling pathways triggered by OGP(10-14) was analyzed using RhoA and Src family kinase (SFK) inhibitors (C3 and PP2) and an immunoperoxidase technique.
OGP(10-14) induces expression of the factor VIII-related antigen, morphologic changes indicative of megakaryocytic differentiation, and a down-regulation of the Fyn Src kinase. These OGP(10-14) effects were prevented by C3 and enhanced by PP2.
The anti-proliferative and pro-differentiating activities of OGP(10-14) on thrombopoietin (TPO)-primed Mo-7e cells are mediated by RhoA and Src kinase pathways as demonstrated by the use of C3 and PP2.
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ABSTRACT: The osteogenic growth peptide (OGP) is a naturally occurring tetradecapeptide that has attracted considerable clinical interest as a bone anabolic agent and hematopoietic stimulator. In vitro studies have demonstrated that OGP directly regulates the bone marrow mesenchymal stem cells' (BMSCs) differentiation into osteoblasts. However, the exact mechanism of this process remains unknown. In the present study, we investigated the role of RhoA/ROCK signaling in differentiation along this lineage using human BMSCs. OGP treatment increased the mRNA level of bone morphogenetic protein-2 and alkaline phosphatase activity after osteogenic induction. Analysis of BMSCs induced in the presence of OGP revealed an increase in RhoA activity, and phosphorylation of FAK and cofilin. The ROCK-specific inhibitors, Y27632, blocked the OGP-induced regulation of BMSC differentiation. Taken together, these data suggest that OGP not only acts on BMSCs to stimulate osteogenic differentiation, but also in a dose-dependent manner, and this effect is mediated via the activation of RhoA/ROCK pathway.Molecular and Cellular Biochemistry 07/2011; 358(1-2):221-7. · 2.33 Impact Factor
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ABSTRACT: Osteogenic growth peptide (OGP) is a 14-mer peptide found in relevant concentration in blood, and its carboxy-terminal fragment [OGP(10-14)] represents the active portion of the full-length peptide. In addition to stimulating bone formation, OGP(10-14) shows hematological activity. In fact, it highly enhances hematopoiesis-affecting stem progenitors. Moreover, OGP(10-14) reduces the growth and induces the differentiation of the hematological tumour cell line trombophoietin(TPO)-primed M07-e by interfering with RhoA and Src kinase pathways. In the present report, we went deeper into this mechanism and evaluated the possible interference of the OGP(10-14) signal pathway with TGFβ1 and TPO receptor Mpl. In OGP(10-14)-treated M07-e cells cultured with or without RhoA and Src kinases inhibitors (C3 and PP2), expression of TGFβ1, Mpl, and Src kinases was analyzed by immunoperoxidase technique. Activated RhoA expression was studied using the G-LISA™ quantitative test. In M07-e cells, both OGP(10-14) and PP2 activate RhoA, inhibit Src kinases, reduce Mpl expression and increase TGFβ1 expression. OGP(10-14) and PP2 show the same behavior, causing an additive effect when associated. OGP(10-14) induces TPO-primed M07-e cells differentiation through RhoA/TGFβ1/SFKs signalling pathway. In particular OGP(10-14) acts as a Src inhibitor, showing the same effects of PP2.Medical science monitor: international medical journal of experimental and clinical research 01/2011; 17(1):SC1-5. · 1.36 Impact Factor