Chromatin compaction and cell death by high molecular weight FGF-2 depend on its nuclear localization, intracrine ERK activation, and engagement of mitochondria.
Fibroblast growth factor 2 (FGF-2) is produced as CUG-initiated, 22-34 kDa or AUG-initiated 18 kDa isoforms (hi- and lo-FGF-2, respectively), with potentially distinct functions. We report that expression of hi-FGF-2 in HEK293 cells elicited chromatin compaction preceding cell death with apoptotic features. Nuclear localization of the intact protein was required as expression of a non-nuclear hi-FGF-2 mutant failed to elicit chromatin compaction. Equally ineffective, despite nuclear localization, was the over-expression of the 18 kDa core sequence (lo-FGF-2). Chromatin compaction by hi-FGF-2 was accompanied by increased cytosolic cytochrome C, and was attenuated either by over-expression of Bcl-2 or by a peptide inhibitor of the pro-apoptotic protein Bax. In addition hi-FGF-2 elicited sustained activation of total and nuclear extracellular signal regulated kinase (ERK1/2) by an intracrine route, as it was not prevented by neutralizing anti-FGF-2 antibodies. Inhibition of the ERK1/2 activating pathway by dominant negative upstream activating kinase, or by PD 98059, prevented chromatin compaction by hi-FGF-2. ERK1/2 activation was not affected by the Bax-inhibiting peptide suggesting that it occurred upstream of mitochondrial involvement. We conclude that the hi-FGF-2-induced chromatin compaction and cell death requires its nuclear localization, intracrine ERK1/2 activation and mitochondrial engagement.
Ma
Xin
X
Institute of Cardiovascular Sciences, SBRC, University of Manitoba, Winnipeg, Manitoba, Canada.
Dang
Xitong
X
Claus
Peter
P
Hirst
Cheryl
C
Fandrich
Robert R
RR
Jin
Yan
Y
Grothe
Claudia
C
Kirshenbaum
Lorrie A
LA
Cattini
Peter A
PA
Kardami
Elissavet
E
D000256:Adenoviridae / Q000235:genetics; D000911:Antibodies, Monoclonal / Q000378:metabolism; D016923:Cell Death / Q000187:drug effects; D002460:Cell Line; D002467:Cell Nucleus / Q000201:enzymology / Q000378:metabolism*; D002843:Chromatin / Q000187:drug effects / Q000502:physiology*; D045304:Cytochromes c / Q000378:metabolism; D003593:Cytoplasm / Q000378:metabolism; D004789:Enzyme Activation / Q000187:drug effects; D048049:Extracellular Signal-Regulated MAP Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D016222:Fibroblast Growth Factor 2 / Q000737:chemistry / Q000235:genetics / Q000494:pharmacology*; D005419:Flavonoids / Q000494:pharmacology; D019793:Fluorescein; D005456:Fluorescent Dyes; D006801:Humans; D020287:In Situ Nick-End Labeling; D007668:Kidney / Q000166:cytology; D008928:Mitochondria / Q000378:metabolism*; D008970:Molecular Weight; D010957:Plasmids; D020033:Protein Isoforms / Q000737:chemistry / Q000235:genetics
D000911:Antibodies, Monoclonal; D002843:Chromatin; D005419:Flavonoids; D005456:Fluorescent Dyes; D020033:Protein Isoforms; D016222:Fibroblast Growth Factor 2; D045304:Cytochromes c; D048049:Extracellular Signal-Regulated MAP Kinases; C093973:2-(2-amino-3-methoxyphenyl)-4H-1-benzopyran-4-one; D019793:Fluorescein