| Budget Amount *help |
¥2,000,000 (Direct Cost: ¥2,000,000)
Fiscal Year 1995: ¥900,000 (Direct Cost: ¥900,000)
Fiscal Year 1994: ¥1,100,000 (Direct Cost: ¥1,100,000)
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| Research Abstract |
The role of rho proteins, which are p21-related small GTP-binding proteins, in megakaryocyte polyploidization was examined using a botulinum C3 exoenzyme (C3), a rho inactivating enzyme.
1. CMK,a megakaryocytic ccell line, expressed high levels of rhoA and rhoC mRNAs whereas rhoB mRNA was expressed at a low level.
2. The addition of C3 caused ADP-ribosylation of the rho proteins in CMK,followed by a higher freque ncy of polyploid cells with increased GPIIb/IIIa antigens. Our study suggests that the rho p21 is a regulatory component in polyploidization and GPIIb/IIIa antigen expression of a megakaryocyte.
We established a new megakaryocytic cell line called KH184, from a patient with sarcoma. We characterized the features of KH184 cells.
1. Neither phorbol ester nor various cytokines such as IL-3, IL-6 and LIF had effect on promoting the growth of of KH184. KH184 provides unique model for the characterization of factors that are implicated in the terminal differentiation of megakarycytes.
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gulation of the expression of cytokine receptor (R9) mRNA is supposed to be one of the mechanisms for modulating the responsiveness of megakaryocyte progenitors to different cytokines during megakaryocyte maturation. We analyzed the characteristics of regulation of IL-3R mRNAs in CMK.
1. CMK expressed IL-3Rbeta-subunit mRNA more strongly than IL-3Ralpha-subunit mRNA.In contrast, KMT2 (stem cell line) expressed IL-3R alpha-subunit more strongly than IL-3R beta-subunit mRNA.TNFalpha weakly augumented IL-3 mRNAs in CMK,whereas TNFalpha markdly enhanced expression of IL-3R mRNA in KMT2. These findings suggest that the expression of IL-3 mRNA varied in the progenitor cells of different lineages.
Increased platelet counts after repeated autologous preoperative blood donations are commonly observed. To clarify the mechanisms of thrombocytosis after phlebotomy, we examined the morphological characteristics of newly circulating platelets and megakaryopoiesis in phlebomotized rats.
1. Fifteen days after the initial phlebotomy the platelet count in phlebomotized rats was higher than control rats. There was no difference in mean platelet volume or platelet distribution width. However, the number of megakaryocytes in phlemotized than in controls. Thes findings indicate that some humoral factors related to megakaryocyte differentiation from late megakaryocyte progenitors, but not from immature multipotential progenitors, may be involved in the induction of increased platelet production during repeated phlebotomies. Less
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