Gallein increases prostaglandin F2α‑induced osteoprotegerin and IL‑6 secretion in osteoblasts.

Gallein is a known Gβγ subunit inhibitor, but its function in bone metabolism, especially in osteoblasts, and its molecular mechanism remains to be elucidated. Osteoprotegerin (OPG), which is secreted from osteoblasts, binds to nuclear factor kB receptor activator (RANK) ligand (RANKL) as a decoy receptor, prevents RANKL-RANK binding, and inhibits bone resorption. IL-6 is not only a bone resorption factor but also as a bone metabolism regulator.

Serotonin reuptake inhibitor suppresses the activation of human platelets by a combination of thrombopoietin and collagen through inhibition of Rac and Rho/Rho-kinase.

Tramadol and duloxetine, reuptake inhibitors of serotonin and noradrenaline, are widely used analgesics. Cytoplasmic serotonin in human platelets reportedly regulates the activity of low-molecular-weight GTP-binding proteins via serotonylation, leading to the modulation of platelet functions. We recently showed that the combination of thrombopoietin and collagen in the low doses synergistically induces human platelet activation via Rac and Rho/Rho-kinase.

Gallein, G protein βγ subunits inhibitor, suppresses the TGF-α-induced migration of hepatocellular carcinoma cells via inhibition of the c-Jun N-terminal kinase.

G protein-coupled receptor (GPCR) signaling regulates a wide range of pathophysiological cell functions via G protein α and βγ subunits. Small molecules targeting the subunits of Gα and Gβγ have been developed as cancer therapeutics. We have previously reported that transforming growth factor-α (TGF-α) induces the migration of human hepatocellular carcinoma (HCC) HuH7 cells through the activation of AKT, p38 mitogen-activated protein kinase (MAPK), Rho-kinase and c-Jun N-terminal kinase (JNK).

Oncostatin M suppresses bone morphogenetic protein-4-induced osteoprotegerin synthesis in MC3T3-E1 osteoblast-like cells: p70 S6 kinase attenuation.

Evidence is accumulating that osteal macrophages, in addition to bone-resorbing osteoclasts and bone-forming osteoblasts, participate vitally in bone remodeling process. Oncostatin M (OSM), an inflammatory cytokine belonging to interleukin-6 superfamily, is recognized as an essential factor secreted by osteal macrophages to orchestrate bone remodeling. Osteoprotegerin (OPG) produced by osteoblasts regulates osteoclastogenesis.