Mechanisms of dead cell DNA degradation and cell-free DNA generation

2019 Fiscal Year Final Research Report

• Project/Area Number: 17K08891
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Research Field: Immunology
• Research Institution: Tokyo University of Science
• Principal Investigator: Mizuta Ryushin 東京理科大学, 研究推進機構生命医科学研究所, 教授 (50297628)
• Project Period (FY): 2017-04-01 – 2020-03-31
• Keywords: DNase γ / DNase1L3 / CAD / ネクローシス / アポトーシス / cfDNA / NETS / liquide biopsy

Outline of Final Research Achievements

Cell-free DNA (cfDNA) (e.g. fetal- or tumor-derived DNA) is DNA found in the blood circulation. It is now widely investigated as a biomarker for prenatal screening, tumor diagnosis, and tumor monitoring as “liquid biopsies”. However, the biological and biochemical aspects of cfDNA remain unclear. Although cfDNA is considered to be mainly derived from dead cells, information is scarce as to whether it is apoptotic or necrotic and what kinds of endonucleases or DNases are involved. We induced in vivo hepatocyte necrosis and apoptosis in mice deficient in DNase γ (also named DNase1L3) and/or caspase-activated DNase (CAD) genes with acetaminophen overdose and anti-Fas antibody treatments. We found that (i) DNase γ was the endonuclease responsible for generating cfDNA in acetaminophen-induced hepatocyte necrosis and (ii) CAD and DNase γ cooperated in producing cfDNA for anti-Fas mediated hepatocyte apoptosis.

Free Research Field

医歯薬

Academic Significance and Societal Importance of the Research Achievements

２つのDNA切断酵素CADおよびDNaseγがcfDNA の生成に関与することが明らかになったことより、酵素の特異性をふまえたcfDNAの評価ならびに精製プロトコールの作製に寄与するものと期待される。また、DNaseγが血流中に漏出したDNAを最初に分解する酵素であることが明らかになったことより、DNAを骨格として形成された血栓の治療に有効であること、またそのような血栓を足場として広がるがん細胞の転移の抑制にも応用できる可能性が示唆された。