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Caspase-8L expression protects CD34+ hematopoietic progenitor cells and leukemic cells from CD95-mediated apoptosis

Mohr, Andrea and Zwacka, Ralf Michael and Jarmy, Gergely and Büneker, Chirlei and Schrezenmeier, Hubert and Döhner, Konstanze and Beltinger, Christian and Wiesneth, Markus and Debatin, Klaus-Michael and Stahnke, Karsten (2005) 'Caspase-8L expression protects CD34+ hematopoietic progenitor cells and leukemic cells from CD95-mediated apoptosis.' Oncogene, 24 (14). pp. 2421-2429. ISSN 0950-9232

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Regulation of sensitivity or resistance for apoptosis by death receptor ligand systems is a key control mechanism in the hematopoietic system. Dysfunctional or deregulated apoptosis can potentially contribute to the development of immune deficiencies, autoimmune diseases, and leukemia. Control of homeostasis starts at the level of hematopoietic stem cells (HSC). To this end, we found that CD34+ hematopoietic progenitor cells are constitutively resistant to CD95-mediated apoptosis and cannot be sensitized during short-term culture to death receptor-mediated apoptosis by cytokioes. Detailed analysis of the death machinery revealed that CD34+ cells do not express caspase-8a/b, a crucial constituent of the death-inducing signaling complex (DISC) of death receptors. Instead, we found a smaller splice variant termed caspase-8L to be present in HSC. Forced expression of caspase-8L using a recombinant lentiviral vector was able to protect hemato-poietic cells from death receptor-induced apoptosis even in the presence of caspase-8a/b. Furthermore, we found that caspase-8L is recruited to the DISC after CD95 triggering, thereby preventing CD95 from connecting to the caspase cascade. These results demonstrate an antiapoptotic function of caspase-8L and suggest a critical role as apoptosis regulator in HSC. Similar to CD34+ HSC, stem cell-derived leukemic blasts from AML(M0) patients only expressed caspase-8L. Additionally we found, caspase-8L expression in several AML and ALL samples. Thus, caspase-8L expression might explain constitutive resistance to CD95-mediated apoptosis in CD34+ progenitor cells and might participate in the development of stem cell-derived and other leukemias by providing protection from regulatory apoptosis. © 2005 Nature Publishing Group All rights reserved.

Item Type: Article
Uncontrolled Keywords: caspase-8; stem cell; apoptosis; splice variant; leukaemia; CD95
Subjects: R Medicine > RC Internal medicine > RC0254 Neoplasms. Tumors. Oncology (including Cancer)
Divisions: Faculty of Science and Health
Faculty of Science and Health > Life Sciences, School of
SWORD Depositor: Elements
Depositing User: Elements
Date Deposited: 29 Jun 2017 10:19
Last Modified: 18 Aug 2022 11:33

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