| Project/Area Number |
63570208
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| Research Category |
Grant-in-Aid for General Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Research Field |
Virology
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| Research Institution | The University of Tokyo |
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Principal Investigator |
IWAMATO Aikichi Univ. of Tokyo, Faculty of Medicine, Assistant Professor, 医学部(医), 講師 (10133076)
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| Co-Investigator(Kenkyū-buntansha) |
YOSIKURA Hiroshi Univ. of Tokyo, Faculty of Medicine, Professor, 医学部(医), 教授 (60012754)
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| Project Period (FY) |
1988 – 1990
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| Project Status |
Completed (Fiscal Year 1990)
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| Budget Amount *help |
¥2,000,000 (Direct Cost: ¥2,000,000)
Fiscal Year 1990: ¥400,000 (Direct Cost: ¥400,000)
Fiscal Year 1989: ¥400,000 (Direct Cost: ¥400,000)
Fiscal Year 1988: ¥1,200,000 (Direct Cost: ¥1,200,000)
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| Keywords | Rous sarcoma virus / XC cell / Morphological Conversion / Adenyl Cyclase / G Protein / 細胞形態変換 / アデニレ-トシクラ-ゼ / アデニレートシクラーゼ |
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| Research Abstract |
Xc is a clonal cell line transformed by Rous sarcoma virus (RSV). XC cells are composed of morphologically different cell types ; one with elongated fusiform shape (L-type) and the other with round morphology (R-type). L-type and R-type cells are different not only in their morphology but also in the adenylyl cyclase activity. Pure cultures of L-type and R-type were obtained by repeated colony isolation. Interestingly XC cells flip-flopped their morphology between L- and R-type. There were polypeptides specific to L or R suggesting that transcriptional activities of some genes are different in these cells. L-type cells are more strongly transformed than R-type cells ; L-type sells made bigger tumors on nude mice in shorter periods and grew more quickly in a semisolid medium. XC cells harbor abors 10 copies of RSV provirus. The restriction pattern of them in the two cell types were exactly the same indicating that L-type and R-type cells originated from a single transformed cell. Northern blot analysis showed that transcripts from RSV proviruses are three fold more abundant in L-type cells. Immunoprecipitation with a tumor-bearing-rabbit serum showed that L-type cells contained two-three fold more pp60^<src>. DNA methylation is a possible cause for these changes.
R-type cells responded sensitively to cholera toxin or forskolin generating lots of cAMP, while L-type cells were refractory. Studies using membrane fractions revealed that both types generated cAMP equally well when they were stimulated with Mn^<2+>, while membranes from L-rype were refractory to the stimuli through G proteins. G proteins were almost the same both quantitatively and qualitatively in the two cell types. Therefore, it was inferred that the interaction between G proteins and the catalyst is somehow inhibited in L-type cells. cDNA cloning of the catalyst from these cells would contribute to clarify the problem and is on the way.
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