The rest of CDK family members have not be found to act a key role in cell cycle procession. During the cell cycle, CDKs keep a relatively steady level compared with their activating protein, the cyclins. During the cell cycle, the concentration of cyclins varies with rising or falling. The periodical oscillations of the cyclins levels regulate the activity of CDK enzymes. In the cell cycle procession, different phases require diverse cyclins to participate in activating the CDKs.There are three D type cyclins (cyclin D1, cyclin D2, cyclin D3) driving the cell cycle procession by binding to CDK4 and CDK6.Cyclins form a complex with CDKs, which will start the activation of CDKs. The cyclins themselves have no activation.The complexes formulation of cyclins and CDKs are necessary for driving the cell cycle into the G1 phases. The synthesis of cyclin D is driven by the stimulation of growth factor during G1 and S phases. Cyclin E drive the cell cycle procession from G1 into S pahses, combining with CDK2.Cyclin A plays an important role regulating the procession into G2 and M phases, which is combined with CDK1 as a maturation-promoting factor.
With the development of economy, more and more environment contamination of hexavalent chromium happen all over the world, especially in the developing countries, like China ,India, South Africa and et al. Last month, in Yunnan province China, a serious hexavalent chromium pollution incident occurred, threatening thousands of people’s lives. Jone A, Stanley,et al have found that the hexavalent chromium causes many health problems like menstrual disorders and infertility, in their recent research, they investigated that the Chromium-VI can induce granulosa cell apoptosis through a distinct apoptosis signaling way. The Chromium-VI prevent the cell cycle procession and proliferation by enhancing the activity of cyclin-dependent kinases while down-regulating the cyclin, cyclin-dependent kinases, and FSH receptor and ER-beta. The effect of Chromium-VI can be lightened by vitamin C. Jone’s research investigates that Chromium-VI can provent the regular cell cycle procession by disorganizing the functionally key protein which play a important role in regulating the cell cycle procession and can be potentially mitigated by vitamin
Xylocydine, a novel small molecular inhibitor specially to the cyclin-dependent kinase, is a potent anti-cancer drug for Hepatocellular carcinoma (HCC).In vivo and cell culture test, Seung-Ju found that the Xylocydine can obviously lower the activity of CDK1,2,7,9 and induce the apoptosis of HCC cells, while have no significant effect on other cancer cells.The Xylocydine can inhibit the phosphorylation of RNA polymerase II at serine residues 5 and 2,through restraining the activity of CDK7 and CDK9.The effects of inducing apoptosis is concerned with reducing the expression level of anti- apoptosis protein including XIAP, survive and Bcl-2.These protein are observed to be down regulated, while the apoptosis proteins including Bax and p53 are markedly improved. The data of in vitro and in vivo test show that xylocydine will be a promisingly potent drug for the therapy of hepatocellular carcinoma.
Seung-Ju et.al investigated the molecular mechanisms of apoptosis induced by xylocydine in Hepatocellular carcinoma cells and follow on they identified its activity in vivo of mouse
model. Xylocydine inhibits Cdk1, Cdk9, Cdk2,and Cdk7 activity in HCC cells. They find that xylocydine can reduce the levels of the phosphorylated Rb and nucleolin, who are the targets of Cdk1 and Cdk2 in cells. Further, xylocydine reduces levels of RNA Pol II phosphorylation at Ser2 and Ser5, who are the targets of Cdk7 and Cdk9 and induce apoptosis of Hepatocellular carcinoma cells. Moreover, accompanying by the apoptosis which xylocydine induces by, anti-apoptotic molecules, surviving, , XIAP, and Bcl-2 decrease in carcinoma cells. The increase of p53 may own to the improved stability of p53 protein, as the levels of Ser392 and Ser15 p53 protein phosphorylation.
Senior marketing analyst Saiko Shasteen is simply hooked on Apoptosis, electronics market, jewelry creating. Besides that she appreciates spending treasured time along with her buddies.21 year-old Orchestra librarian Saiko Shasteen prefers Cell Cycle, video games, origami. And finally she gets is getting her stimulus from following a New york islanders icehockey-game.Nashville-born Saiko Shasteen certainly enjoys Cell Cycle artwork, camping. Things she prize the most is discovering and going to new towns, cities and places around the world to provide an example, Klatovy.