u-0126 and echistatin

Cellular processes are regulated by signals generated by adhesion receptors and growth factor receptors. IGFbinding protein 1 (IGFBP-1) is a molecule which may affect the both signaling pathways through inactivation of IGF-I (ligand for IGF-IR) and binding to RGD region of integrin receptors. Whether this phenomenon is important in communication between insulin-like growth factor receptor (IGF-IR) and β1-integrin receptor in regulation of prolidase activity and collagen biosynthesis is the aim of this study.. We studied the effects of IGFBP-1, IGF-I, thrombin (integrin activator), echistatin (disintegrin), phosphatidylinositol 3-kinase inhibitor (LY-294002) and ERK 1/2 inhibitors (PD98059 and UO126) on prolidase activity, collagen biosynthesis and expression of proteins participating in pathways generated by these receptors.. Stimulation of β1-integrin and IGF-I receptors by standard ligands was proved to up-regulate collagen synthesis in cultured fibroblasts. IGFBP-1, similarly as echistatin and studied inhibitors, contributed to down-regulation of ERK1/2, Akt, mTOR expression and up-regulation of NFκB. It was accompanied by parallel decrease in prolidase activity and collagen biosynthesis.. The data suggest that "cross talk" between IGF-I receptor and integrin receptor may play important role in regulation of prolidase activity and collagen biosynthesis.

Topics: Butadienes; Cell Line; Chromones; Collagen; Dipeptidases; Enzyme Inhibitors; Fibroblasts; Flavonoids; Humans; Insulin-Like Growth Factor Binding Protein 1; Insulin-Like Growth Factor I; Integrin beta1; Intercellular Signaling Peptides and Proteins; Morpholines; Nitriles; Peptides; Phosphorylation; Receptor Cross-Talk; Receptor, IGF Type 1; Signal Transduction; Skin; Thrombin

Transforming growth factor-beta (TGF-beta) is released from the matrix during bone resorption and has been implicated in the pathogenesis of giant cell tumors of bone and the expansion of breast cancer metastases in bone. Because osteoclasts mediate tumor-induced osteolysis, we investigated whether TGF-beta stimulates osteoclast recruitment. Osteoclasts were isolated from rat long bones and time-lapse video microscopy was used to monitor their morphology and motility. Within 5 minutes, TGF-beta (0.1 nM) induced dynamic ruffling, with 65% of osteoclasts displaying membrane ruffles compared with 35% in untreated controls. Over a 2-h period, osteoclasts exhibited significant directed migration toward a source of TGF-beta, indicating chemotaxis. echistatin, an alphavbeta3 integrin blocker that inhibits macrophage colony-stimulating factor (M-CSF)-induced osteoclast migration, did not prevent the migration of osteoclasts toward TGF-beta. In contrast, a beta1 integrin blocking antibody inhibited osteoclast chemotaxis toward TGF-beta but not M-CSF. These data indicate the selective use of integrins by osteoclasts migrating in response to different chemotaxins. In addition, wortmannin and U0126 inhibited TGF-beta-induced chemotaxis, suggesting involvement of the phosphatidylinositol 3 (PI 3) kinase and mitogen-activated protein (MAP) kinase signaling pathways. Physiologically, TGF-beta, may coordinate osteoclast activity by recruiting osteoclasts to existing sites of resorption. Pathologically, TGF-beta-induced osteoclast recruitment may be critical for expansion of primary and metastatic tumors in bone.

Topics: Androstadienes; Animals; Butadienes; Cell Membrane; Cell Size; Cell Surface Extensions; Cells, Cultured; Chemotaxis; Enzyme Inhibitors; Femur; Integrins; Intercellular Signaling Peptides and Proteins; Macrophage Colony-Stimulating Factor; Microscopy, Video; Mitogen-Activated Protein Kinases; Nitriles; Osteoclasts; Peptides; Phosphoinositide-3 Kinase Inhibitors; Rats; Rats, Wistar; Signal Transduction; Tibia; Transforming Growth Factor beta; Wortmannin