2001 Fiscal Year Final Research Report Summary
Analysis of expression and function of myosins in hematological cells
| Project/Area Number |
12671004
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Hematology
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| Research Institution | Kitasato University |
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Principal Investigator |
HIGASHIHARA Masaaki Kitasato University, School of Medicine Professor, 医学部, 教授 (80165084)
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| Co-Investigator(Kenkyū-buntansha) |
TAKAISHI Masaaki Kitasato University, School of Medicine Research Associate, 医学部, 助手 (10256307)
AKIYAMA Nobu Kitasato University, School of Medicine Research Associate, 医学部, 助手 (50286358)
HORIE Ryoichi Kitasato University, School of Medicine Assistant Professor, 医学部, 講師 (80229228)
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| Project Period (FY) |
2000 – 2001
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| Keywords | myosin / myosin heavy chain / myosin light chain / isoform / cloning / platelet / lymphocyte / unconventional myosin |
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| Research Abstract |
Our projects provided three conclusions:
1) Human platelets express mRNAs which encode MHC-A exclusively, further suggesting that MHC-A is endogenously synthesed in peripheral blood platelets as well as bone marrow megakarypcytes.
2) In human lymphocytes, MHC-A is expressed avandantely as compared with unconventional myosin. Further we found that MHC-A had two isoforms; 6.0kbp and 7.5kbp. RT-PCR and northern turning showed several unconventional myosins such as I-c, brush border-I, I-β, V, VIIA, IXA, IXB, XV to less extent in lymphocytes.
3) The 20 kDa regulatory myosin light chain (MLC-2) plays an important role in regulating contractile activity in both nonmuscle and smooth muscles. Since MLC genes of hematopoietic cells have yet to be characterized, we cloned the full-length cDNAs of MLC-2 and 17 kDa essential myosin light chain (MLC-3) from Meg-01, a human megakaryoblastic leukemia cell line. Both MLC-2 and MLC-3 gene are transcribed ubiquitously in various hematopoietic cells. The MLC-2 open reading frame of 516 nucleotides encoding a protein of 172 residues was detected in cloned cDNA of 967 nucleotides. The Ca2+- binding domain and five phosphorylation sites were highly conserved. The derived amino acid sequence has a 97.1%, 95.9% and 92.4% homology with that of rat aortic smooth muscle, Xenopus oocytes, and chicken gizzard smooth muscle, respectively. The MLC-3 open reading frame of 453 nucleotides encoding a protein of 151 residues was detected in cloned cDNA of 742 nucleotide. The MLC-3 protein is 99.3% identical to that of human fibroblasts. These results suggest that hematopoietic myosin light chain proteins are identical to those of other nonmuscle cells and smooth muscle, thus differing from skeletal and cardiac muscles. MLCs of smooth muscle and nonmuscle cells, including hematopoietic cells, are probably encoded by the same gene.
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