Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:2.7.11.26 (GSK)
 6,788 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

In search of chemical substances applicable for the treatment of cancer and other proliferative disorders, we studied the signal transduction of Dictyostelium differentiation-inducing factors (DIFs) in mammalian cells mainly using HeLa cells. Although DIF-1 and DIF-3 both strongly inhibited cell proliferation by inducing G(0)/G(1) arrest, DIF-3 was more effective than DIF-1. DIF-3 suppressed cyclin D1 expression at both mRNA and protein levels, whereas the overexpression of cyclin D1 overrode DIF-3-induced cell cycle arrest. The DIF-3-induced decrease in the amount of cyclin D1 protein preceded the reduction in the level of cyclin D1 mRNA. The decrease in cyclin D1 protein seemed to be caused by accelerated proteolysis, since it was abrogated by N-acetyl-Leu-Leu-norleucinal, a proteasome inhibitor. DIF-3-induced degradation of cyclin D1 was also prevented by treatment with lithium chloride, an inhibitor of glycogen synthase kinase-3beta (GSK-3beta), suggesting that DIF-3 induced cyclin D1 proteolysis through the activation of GSK-3beta. Indeed, DIF-3 dephosphorylated Ser(9) and phosphorylated tyrosine on GSK-3beta, and it stimulated GSK-3beta activity in an in vitro kinase assay. Moreover, DIF-3 was revealed to induce the nuclear translocation of GSK-3beta by immunofluorescent microscopy and immunoblotting of subcellular protein fractions. These results suggested that DIF-3 activates GSK-3beta to accelerate the proteolysis of cyclin D1 and that this mechanism is involved in the DIF-3-induced G(0)/G(1) arrest in mammalian cells.
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PMID:Dictyostelium differentiation-inducing factor-3 activates glycogen synthase kinase-3beta and degrades cyclin D1 in mammalian cells. 1252 40

Differentiation-inducing factors (DIFs) are morphogens which induce cell differentiation in Dictyostelium. We reported that DIF-1 and DIF-3 inhibit proliferation and induce differentiation in mammalian cells. In this study, we investigated the effect of DIF-1 on oral squamous cell carcinoma cell lines NA and SAS, well differentiated and poorly differentiated cell lines, respectively. Although DIF-1 did not induce the expression of cell differentiation makers in these cell lines, it inhibited the proliferation of NA and SAS in a dose-dependent manner by restricting the cell cycle in the G0/G1 phase. DIF-1 induced cyclin D1 degradation, but this effect was prevented by treatment with lithium chloride and SB216763, the inhibitors of glycogen synthase kinase-3beta (GSK-3beta). Depletion of endogenous GSK-3beta by RNA interference also attenuated the effect of DIF-1 on cyclin D1 degradation. Therefore, we investigated the effect of DIF-1 on GSK-3beta and found that DIF-1 dephosphorylated GSK-3beta on Ser9 and induced the nuclear translocation of GSK-3beta, suggesting that DIF-1 activated GSK-3beta. Then, we examined the effect of DIF-1 on cyclin D1 mutants (Thr286Ala, Thr288Ala, and Thr286/288Ala). We revealed that Thr286Ala and Thr286/288Ala mutants were highly resistant to DIF-1-induced degradation compared with wild-type cyclin D1, indicating that the phosphorylation of Thr286 was critical for cyclin D1 degradation induced by DIF-1. These results suggest that DIF-1 induces degradation of cyclin D1 through the GSK-3beta-mediated phosphorylation of Thr286.
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PMID:Differentiation-inducing factor-1 induces cyclin D1 degradation through the phosphorylation of Thr286 in squamous cell carcinoma. 1615 39

Differentiation-inducing factors (DIFs) are putative morphogens that induce cell differentiation in Dictyostelium discoideum. We previously reported that DIF-3 activates glycogen synthase kinase-3beta (GSK-3beta), resulting in the degradation of cyclin D1 in HeLa cells. In this study, we investigated the effect of DIF-3 on cyclin D1 mutants (R29Q, L32A, T286A, T288A, and T286A/T288A) to clarify the precise mechanisms by which DIF-3 degrades cyclin D1 in HeLa cells. We revealed that T286A, T288A, and T286A/T288A mutants were resistant to DIF-3-induced degradation compared with wild-type cyclin D1, indicating that the phosphorylation of Thr(286) and Thr(288) were critical for cyclin D1 degradation induced by DIF-3. Indeed, DIF-3 markedly elevated the phosphorylation level of cyclin D1, and mutations introduced to Thr(286) and/or Thr(288) prevented the phosphorylation induced by DIF-3. Depletion of endogenous GSK-3beta and dual-specificity tyrosine phosphorylation regulated kinase 1B (DYRK1B) by RNA interference attenuated the DIF-3-induced cyclin D1 phosphorylation and degradation. The effect of DIF-3 on DYRK1B activity was examined and we found that DIF-3 also activated this kinase. Further, we found that not only GSK-3beta but also DYRK1B modulates cyclin D1 subcellular localization by the phosphorylation of Thr(288). These results suggest that DIF-3 induces degradation of cyclin D1 through the GSK-3beta- and DYRK1B-mediated threonine phosphorylation in HeLa cells.
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PMID:Involvement of GSK-3beta and DYRK1B in differentiation-inducing factor-3-induced phosphorylation of cyclin D1 in HeLa cells. 1704 23