Heterotrimeric G proteins of the G q class have been implicated in signaling pathways regulating cardiac growth under physiological and pathological conditions. Knockout mice carrying inactivating mutations in both of the widely expressed Gα q class genes, Gα q and Gα 11 , demonstrate that at least two active alleles of these genes are required for extrauterine life. Mice carrying only one intact allele [Gα q (-/ϩ) ;Gα 11 (-/-) or Gα q (-/-) ;Gα 11 (-/ϩ) ] died shortly after birth. These mutants showed a high incidence of cardiac malformation. In addition, Gα q (-/-) ;Gα 11 (-/ϩ) newborns suffered from craniofacial defects. Mice lacking both Gα q and Gα 11 [Gα q (-/-) ;Gα 11 (-/-) ] died at embryonic day 11 due to cardiomyocyte hypoplasia. These data demonstrate overlap in Gα q and Gα 11 gene functions and indicate that the G q class of G proteins plays a crucial role in cardiac growth and development.

We provide a novel development in jet physics by predicting the energy profiles of light-quark and gluon jets in the framework of perturbative QCD. Resumming large logarithmic contributions to all orders in the coupling constant, our predictions are shown to agree well with Tevatron CDF and Large Hadron Collider CMS data. We also extend our resummation formalism to the invariant mass distributions of light-quark and gluon jets produced in hadron collisions. The predicted peak positions and heights in jet mass distributions are consistent with CDF data within uncertainties induced by parton distribution functions.

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Molecular mechanisms of cell-cycle arrest caused by gambogic acid (GA), a natural product isolated from the gamboge resin of Garcinia hanburryi tree, have been investigated using BGC-823 human gastric carcinoma cells as a model. Based on our 3-(4,5-dimethylthiazol-2-yl)- 2,5-diphenyltetrazoliumbromide (MTT) assay and flow cytometric analysis, treatment of BGC-823 cells with growth suppressive concentrations of GA caused an irreversible arrest in the G(2)/M phase of the cell cycle. Western blot analysis demonstrated that GA-induced cell-cycle arrest in BGC-823 cells was associated with a significant decrease in CDC2/p34 synthesis, which led to the accumulation of phosphorylated-Tyr(15) (inactive) form of CDC2/p34. Real-time PCR, western blot and kinase activity assays revealed that GA-induced reduction of CDC2/p34 expression was mediated through the inhibition of cyclin-dependent kinase (CDK)-activating kinase (CDK7/cyclin H) activity. In addition, GA-treated cells were shown to have a low level of CDK7 kinase-phosphorylated-Thr(161) CDC2/p34 (active). Taken together, our results suggested that the inhibited proliferation of GA-treated BGC-823 cells was associated with the decreased production of CDK7 mRNA and protein, which in turn, resulted in the reduction of CDK7 kinase activity. The reduced CDK7 kinase activity is responsible for the inactivation of CDC2/p34 kinase and the irreversible G(2)/M phase cell-cycle arrest of human gastric carcinoma BGC-823 cells.

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