ucn-1028-c and pyrazolanthrone

Mitogen-activated protein (MAP) and tyrosine kinases play an important role in regulating smooth muscle contraction of the gastrointestinal (GI) tract. Interstitial cells of Cajal (ICCs) are pacemaker cells that regulate GI smooth muscle activity. Thus, the role of MAP and tyrosine kinases on the pacemaker potentials of colonic ICCs was investigated.. Cultured ICCs were prepared from mice colons, and their pacemaker potentials were recorded using whole-cell patch clamping.. In current-clamping mode, colonic ICCs displayed spontaneous pacemaker potentials. SB203580 (a p38 MAP kinase inhibitor), SP600125 (a c-jun NH2-terminal kinase (JNK) inhibitor), genistein and herbimycin A (tyrosine kinase inhibitors) blocked the generation of pacemaker potentials. However, PD98059 (a p42/44 MAP kinase inhibitor) had no effects on pacemaker potentials. LY-294002 (phosphoinositide 3-kinase inhibitor) also reduced the pacemaker potential frequency but calphostin C and chelerythrine (protein kinase C inhibitors) had no effects. However, PD98059, SB203589, SP600125, genistein, herbimycin A, LY-294002, and calphostin C had no effect on normal pacemaker activity in small intestinal ICCs.. Endogenous p38 MAP kinases, JNKs, tyrosine kinases, and PI3-kinases participate in the generation of pacemaker potentials in colonic ICCs but not in ICCs of the small intestine.

Topics: Animals; Anthracenes; Benzophenanthridines; Cells, Cultured; Chromones; Colon; Flavonoids; Genistein; Imidazoles; Interstitial Cells of Cajal; Intestine, Small; Membrane Potentials; Mice; Mitogen-Activated Protein Kinases; Morpholines; Naphthalenes; Protein-Tyrosine Kinases; Pyridines; Rifabutin

Inorganic phosphate (Pi) transport probably represents an important function of bone-forming cells in relation to extracellular matrix mineralization. In the present study, we investigated the effect of prostaglandin D2 (PGD2) on Pi transport activity and its intracellular signaling mechanism in MC3T3-E1 osteoblast-like cells. PGD2 stimulated Na-dependent Pi uptake time- and dose-dependently in MC3T3-E1 cells during their proliferative phase. A protein kinase C (PKC) inhibitor calphostin C partially suppressed the stimulatory effect of PGD2 on Pi uptake. The selective inhibitors of mitogen-activated protein (MAP) kinase pathways such as ERK, p38 and Jun kinases suppressed PGD2-induced Pi uptake. The inhibitors of phosphatidylinositol (PI) 3-kinase and S6 kinase reduced this effect of PGD2, while Akt kinase inhibitor did not. These results suggest that PGD2 stimulates Na-dependent Pi transport activity in the phase of proliferation of osteoblasts. The mechanisms responsible for this effect are activation of PKC, MAP kinases, PI 3-kinase and S6 kinase.

Topics: 3T3 Cells; Animals; Anthracenes; Butadienes; Cells, Cultured; Chromones; Dose-Response Relationship, Drug; Imidazoles; Mice; Morpholines; Naphthalenes; Nitriles; Osteoblasts; Phosphates; Prostaglandin D2; Pyridines; Signal Transduction; Sirolimus; Sodium

We have reported that endothelin-1 (ET-1) activates p38 mitogen-activated protein (MAP) kinase through protein kinase C in osteoblast-like MC3T3-E1 cells, and that p38 MAP kinase plays a role in the ET-1-induced heat shock protein 27 (HSP27). Recently, we found that stress-activated protein kinase/c-Jun N-terminal kinase (SAPK/JNK) is activated by ET-1 in these cells. In the present study, we have investigated the involvement of SAPK/JNK in ET-1-induced HSP27 in MC3T3-E1 cells.. The concentration of HSP27 in soluble extracts of the cells, the expression of mRNA for HSP27, and the phosphorylation of SAPK/JNK were determined by an enzyme immunoassay, Northern blot analysis, and Western blot analysis respectively.. SP600125, a specific inhibitor of SAPK/JNK, markedly reduced ET-1-stimulated HSP27 accumulation. The inhibitory effect of SP600125 was dose dependent in the range between 1 and 50 microM. SP600125 reduced the ET-1-increased level of HSP27 mRNA. Calphostin C and Go 6976, inhibitors of protein kinase C, reduced the ET-1-induced phosphorylation of SAPK/JNK. 12-O-Tetradecanoylphorbol-13-acetate, a direct activator of protein kinase C, induced SAPK/JNK phosphorylation, which was suppressed by SP600125. A combination of SP600125 and p38 MAP kinase inhibitor such as SB203580 and PD169316 additively reduced the ET-1-stimulated accumulation of HSP27.. These results strongly suggest that JNK plays a part in ET-1-induced HSP27 in addition to p38 MAP kinase in osteoblasts.

Topics: Animals; Anthracenes; Blotting, Northern; Blotting, Western; Carbazoles; Endothelin-1; Enzyme Activators; Enzyme Inhibitors; Gene Expression Regulation; Heat-Shock Proteins; Immunoenzyme Techniques; Indoles; JNK Mitogen-Activated Protein Kinases; MAP Kinase Kinase 4; Mice; Mitogen-Activated Protein Kinase Kinases; Mitogen-Activated Protein Kinases; Molecular Chaperones; Naphthalenes; Neoplasm Proteins; Osteoblasts; p38 Mitogen-Activated Protein Kinases; RNA, Messenger; Tetradecanoylphorbol Acetate