1997 Fiscal Year Final Research Report Summary
Apoptosis in Human leukemia and Preleukemia
| Project/Area Number |
08457276
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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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 | KYOTO UNIVERSITY |
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Principal Investigator |
YOSHIDA Yataro KYOTO UNIVERSITY Center for South East Asian Studies Division of Human Environment, Professor, 東南アジア研究センター, 教授 (80064525)
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| Co-Investigator(Kenkyū-buntansha) |
SASADA Masataka KYOTO UNIVERSITY College of Medical Technology, Division of Medical Technology,, 医療短期大学部, 教授 (30144364)
OGUMA Shigeru KYOTO UNIVERSITY Department of Hematology/Oncology, Graduate School of Medicine,, 医学研究科, 助手 (00169260)
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| Project Period (FY) |
1996 – 1997
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| Keywords | apoptosis / endonuclease / human leukemia and preleukemia / hematopoietic cell differentiation |
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| Research Abstract |
1.We have isolated Mg2+/Mn2+-dependent endonuclease activies from nuclear aswell as cytoplasm of human myeloid leukemia cells. The former had a molecular size of 30kD, while that of the latter was 130-140kD, indicating a dimer form in the cytoplasm. Both are capable of producing nucleosomal-size DNA fragmentation when added to DEPC-treated nuclei as substrate. The cleavage pattern of 3'-OH and 5'-P, inhibition by known inhibitors of apoptosis suggest their participation in apoptotic process.
2.Hematopoietic cells contain at least three types of endonucleases distinct from each other in cation dependency and inhibition by distinct agents. The stem cells, and immature blast cells from leukemia and preleukemia have a high activity for Mg2+/Mn2+-dependent endonuclease. Differentiation is associated with a decrease of this enzyme and generally with emergence of new types of endonuclease activities, i. e., Mg2+/Ca2+-dependent and acidic endonucleases. Differentiation experiment of leukemia and preleukemia cells indicate that susceptibility to apoptosis is not concomitant with cell differentiation. Thus, apoptosis apparently is a cellular event distinct from differentiation.
3.The pulse field method is useful in studing the early biochemical events preceding the nucleosomal-size DNA fragmentation, which is a well-known parameter for apoptosis as the laddering. We could dissect the processes in DNA cleavage taking place early following the etoposide treatment of human leukemia cells. We could demonstrate a sequential cleavage of DNA from a huge size (2-5 Mb) DNA cleavage down to less than 50 Kb DNA fragments. Dichloroisocoumarine can specifically inhibit both apoptotic morphology and less than 50 Kb DNA fragments which is in the size range seen in DNA laddering.
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