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Characterization of caspase proteases in cytokine‐dependent myeloid progenitor cells using enzyme affinity labeling
Author(s) -
Cho Richard L.,
Johnson Daniel E.
Publication year - 1999
Publication title -
journal of cellular biochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.028
H-Index - 165
eISSN - 1097-4644
pISSN - 0730-2312
DOI - 10.1002/(sici)1097-4644(19990401)73:1<79::aid-jcb9>3.0.co;2-r
Subject(s) - progenitor cell , caspase , myeloid , microbiology and biotechnology , biology , cytokine , interleukin 3 , proteases , chemistry , apoptosis , stem cell , biochemistry , cancer research , t cell , programmed cell death , immunology , enzyme , antigen presenting cell , immune system
Bone marrow‐derived myeloid progenitor cells are dependent on the presence of cytokines such as interleukin‐3 (IL‐3) for their survival. The withdrawal of IL‐3 from IL‐3‐dependent myeloid progenitors results in death via an apoptotic program. Previous studies have shown that IL‐3 withdrawal induces the activities of caspase proteases. However, the molecular identities of myeloid progenitor caspases have not been determined. In this study, we used an affinity labeling reagent (biotin‐YVAD‐acyloxymethyl ketone) that binds to processed active caspase subunits, to study caspase activation in 32D and FDCP‐1 myeloid progenitor cells. After IL‐3 withdrawal, we detected affinity labeling of caspase subunits of 20, 17, and 16 kDa in both cell lines. Surprisingly, affinity labeling of the 20‐ and 17‐kDa proteins, but not the 16‐kDa protein, was also detected in healthy cells maintained in the presence of IL‐3. By contrast, in cytokine‐independent cell lines, affinity labeling of caspase subunits was detected only after treatment with an apoptotic stimulus. Immunoblotting experiments showed that caspase‐3 constitutes at least a portion of the 20‐ and 17‐kDa affinity‐labeled proteins detected in the myeloid progenitor cell lines. Taken together, these data provide direct evidence of caspase activation in cytokine‐dependent myeloid progenitors, and suggest that unique apoptotic pathways may exist in these cells. J. Cell. Biochem. 73:79–89, 1999. © 1999 Wiley‐Liss, Inc.