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Heat shock protein 70 can interact with and also prevent the high molecular weight FGF2‐induced apoptotic chromatin compaction
Author(s) -
Ma Xin,
Santiago JonJon,
Nickel Barbara E.,
Fandrich Robert R.,
Kardami Elissavet
Publication year - 2011
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.25.1_supplement.lb16
Subject(s) - hsp70 , chromatin , gene isoform , microbiology and biotechnology , nucleus , cytosol , apoptosis , chromatin immunoprecipitation , heat shock protein , nuclear protein , chemistry , cell nucleus , biology , biochemistry , transcription factor , dna , gene expression , gene , promoter , enzyme
Fibroblast growth factor 2 (FGF2) is translated as high molecular weight (hi) and low molecular weight (lo) isoforms. We reported that increased nuclear expression of hi but not lo FGF2 elicited chromatin compaction and apoptotic cell death. We have begun investigating the role of hi FGF2 isoform‐specific interacting partners in modulating its pro‐apoptotic effect. Isoform‐specific affinity chromatography was used to capture interacting proteins from cell cytosolic and nuclear fractions. Nuclear proteins that bound only to the hi FGF2‐affinity column were identified by MS/MS peptide sequencing, and included the heat shock protein 70 (hsp70). Hsp70 was confirmed as a hi (but not lo) FGF2 interacting partner by co‐immunoprecipitation experiments. Overexpession of hsp70 prevented the hi FGF2‐induced chromatin compaction in cardiomyocytes. While hsp70 was mainly cytosolic in the absence of over‐expressed hi FGF2, it translocated to the nucleus in the presence of hi FGF2 over‐expression. The nuclear pattern of hsp70 localization partially overlapped with that of hi FGF2, suggesting interaction in situ. In conclusion, hsp70 interacts with hi but not lo FGF2, and is capable of preventing nuclear compaction by hi FGF2. It is possible that an in situ interaction between hsp70 and hi FGF2 is preventing the latter from exerting its apoptotic chromatin compaction effects.