Involvement of Cx43 phosphorylation in 5'-N-ethylcarboxamide-induced migration and proliferation of mouse embryonic stem cells.

Despite a lot of gap junction research, the complex connection between gap junction and cell proliferation remains an exciting area of investigation. Thus, we examined the effect of connexin 43 (Cx43) on the migration and proliferation of embryonic stem (ES) cells and its related signaling pathways following stimulation with the adenosine analogue 5'-N-ethylcarboxamide (NECA). NECA increased phosphorylation of Cx43 which was blocked by caffeine, a non-selective adenosine receptor antagonist. In experiment to measure the gap junctional intercellular communication, NECA blocked transfer of Lucifer yellow to neighboring cells in a scrape loading/dye transfer (SL/DT) assay. In addition, NECA-induced phosphorylation of phosphoinositide 3-kinase (PI3K)/Akt, protein kinase C (PKC), mitogen-activated protein kinases (MAPKs), and nuclear factor-kappa B (NF-kappaB) signal pathways. Inhibition of these signaling pathways reduced NECA-induced phosphorylation of Cx43. Moreover, NECA-treated cells demonstrated phosphorylation of Src, which was blocked by caffeine. In this experiment, a disruption of Cx43 using Cx43-specific small interfering RNA (siRNA) also enhanced Src phosphorylation. In a further study, phosphorylations of integrin beta1, focal adhesion kinase (FAK), and paxillin by NECA were restrained by caffeine as well as the Src blocker, PP2. Finally, we identified that NECA-stimulated cell migration and expressions of cell-cycle regulatory proteins [cyclin D1, cyclin-dependent kinase (CDK) 4, cyclin E, and CDK2]; these increases were inhibited by caffeine, or PP2. We conclude that NECA-stimulated Cx43 phosphorylation mediated by PI3K/Akt, PKC, MAPKs, and NF-kappaB, which subsequently stimulated cell migration and proliferation through Src, integrin beta1, FAK, and paxillin signal pathways.

Kim MO ，Lee YJ ，Han HJ 《-》

5'-N-ethylcarboxamide induces IL-6 expression via MAPKs and NF-kappaB activation through Akt, Ca(2+)/PKC, cAMP signaling pathways in mouse embryonic stem cells.

Kim MO ，Kim MH ，Lee SH ，Suh HN ，Lee YJ ，Lee MY ，Han HJ ... -  《-》

Involvement of caveolin-1 in fibronectin-induced mouse embryonic stem cell proliferation: role of FAK, RhoA, PI3K/Akt, and ERK 1/2 pathways.

Park JH ，Ryu JM ，Han HJ 《-》

Caveolin-1 and integrin β1 regulate embryonic stem cell proliferation via p38 MAPK and FAK in high glucose.

The involvement of caveolin-1 (Cav-1) and integrin β1 (IN β1) in regulation of embryonic stem (ES) cell growth by high glucose is by no means clear cut. Therefore, the aim of this study was to examine the influence of high glucose on Cav-1 and IN β1 expression in mouse ES cells and their signaling pathways to modulate proliferation. High glucose significantly increased Cav-1 and IN β1 expression. In addition, increased IN β1 expression was inhibited by Cav-1 small interfering RNA (siRNA). High glucose caused reactive oxygen species generation and p38 mitogen-activated protein kinase (MAPK) phosphorylation. Inhibition of p38 MAPK blocked high glucose-induced Cav-1 and fibronectin (FN) expression. Moreover, phosphorylation of both Src and focal adhesion kinase (FAK) were increased by high glucose, which were inhibited by IN β1 antibody. In addition, high glucose increased the expression levels of PINCH1/2, integrin-linked kinase (ILK), and α-parvin [PIP] complex proteins, which were all inhibited by the FAK siRNA and Src specific inhibitor (PP2, 10(-7)  M). High glucose also increased F-actin expression, which was inhibited by ILK, PINCH1/2, and α-parvin siRNAs. Finally, high glucose-induced increase of ES cell proliferation was inhibited by TRIO and F-actin binding protein (TRIOBP) siRNA. The results demonstrate that high glucose-induced Cav-1 and IN β1 activation can stimulate ES cell proliferation through the modification of focal adhesion signaling pathways.

Lee SH ，Lee YJ ，Park SW ，Kim HS ，Han HJ ... -  《-》

High glucose regulates cyclin D1/E of human mesenchymal stem cells through TGF-beta1 expression via Ca2+/PKC/MAPKs and PI3K/Akt/mTOR signal pathways.

The elucidation of factors that support human mesenchymal stem cells (hMSCs) growth has remained unresolved partly because of the reliance of many researchers on ill-defined, proprietary medium formulation. Thus, we investigated the effects of high glucose (D-glucose, 25 mM) on hMSCs proliferation. High glucose significantly increased [(3)H]-thymidine incorporation and cell-cycle regulatory protein expression levels compared with 5 mM D-glucose or 25 mM L-glucose. In addition, high glucose increased transforming growth factor-beta1 (TGF-beta(1)) mRNA and protein expression levels. High glucose-induced cell-cycle regulatory protein expression levels and [(3)H]-thymidine incorporation, which were inhibited by TGF-beta(1) siRNA transfection and TGF-beta(1) neutralizing antibody treatment. High glucose-induced phosphorylation of protein kinase C (PKC), p44/42 mitogen-activated protein kinases (MAPKs), p38 MAPK, Akt, and mammalian target of rapamycin (mTOR) in a time-dependent manner. Pretreatment of PKC inhibitors (staurosporine, 10(-6) M; bisindolylmaleimide I, 10(-6) M), LY 294002 (PI3 kinase inhibitor, 10(-6) M), Akt inhibitor (10(-5) M), PD 98059 (p44/42 MAPKs inhibitor, 10(-5) M), SB 203580 (p38 MAPK inhibitor, 10(-6) M), and rapamycin (mTOR inhibitor, 10(-8) M) blocked the high glucose-induced cellular proliferation and TGF-beta(1) protein expression. In conclusion, high glucose stimulated hMSCs proliferation through TGF-beta(1) expression via Ca(2+)/PKC/MAPKs as well as PI3K/Akt/mTOR signal pathways.

Ryu JM ，Lee MY ，Yun SP ，Han HJ ... -  《-》