| Co-Investigator(Kenkyū-buntansha) |
HIRAYAMA Etsuko Kyoto Pharmaceutical University, Department of Cell Biology, Assistant., 薬学部, 助手 (10247786)
ADACHI Toshiyuki Kyoto Pharmaceutical University, Department of Cell Biology, Assistant., 薬学部, 助手 (40202634)
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| Research Abstract |
For investigating the mechanism of skeletal myoblastdifferentiation, especiallymyoblast fusion, we established QM-RSV cells, quail myoblasts transformed with a temperature-sensitive mutant of Rous sarcoma virus. QM-RSV cells proliferate at 35.5ﾟC, a permissive temperature for RSV, but differentiateat 41ﾟC, anonpermissive temperature, with the formation of multinucleated myotubesand myofibrilbundles appear in myotubes with maturation.
As a good tool for analysis, we had prepared a monoclonal antibody, H-145 that inhibits myotube formation of QM-RSV cells. The dynamic distribution of H-145 antigen during differentiationof QM-RSV cells was examined by indirect-immunofluorencent staining using H-145. The results suggest that quantitative expression of H-145 antigen on the cell surface is a prerequisite for myoblast fusion and it related directly to a step of membrane fusion upon differentiation of QM-RSV cells.
On the other hand, detailed experiments of a muscle regulatory factor, myogenin showed that myogenin expression is one of the indispensable conditions for the acquisition of commitment to differentiation, and is regulatedby tyrosinephosphorylation and dephosphorylation of some protein(s) in QM-RSV cells. Further, myogenin was continuously expressed in myotubes not having striated structures comprised of myofibrils, but not in myotubes having the structures, These results also suggests that myogenin is not only requiredfor early steps during differentiation but also maturation steps of my otubes.
In addition, when the characteristics of cell membranes in myoblast differentiation was investigated by HVJ(Sendai virus)-mediatedcells fusion reaction, it was suggested that the cell membranes of myoblasts changed to a fusion-capable state for myotube formation during differentiation.
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