Altered expression of Bag-1 in Coxsackievirus B3 infected mouse heart.
OBJECTIVE
The mechanisms by which Coxsackie B viruses cause myocarditis or dilated cardiomyopathy are not well understood. This study examined changes in the expression of cardiac genes resulting from Coxsackievirus B3 (CVB3) infection of mice.


METHODS
Mice (five per group) were experimentally infected with CVB3 or mock-infected with diluent. Altered expression of genes was initially identified by cDNA array, and confirmed by semiquantitative RT-PCR, western blot and immunohistochemistry.


RESULTS
Forty-two up-regulated or down-regulated genes were observed in cDNA arrays carrying 588 known mouse genes. Among these, one down-regulated gene, Bag-1, known to be involved in inhibition of apoptosis and modulation of chaperone activity, was investigated further. Semiquantitative RT-PCR showed that Bag-1 expression was down-regulated by up to 30% in virus-infected mouse heart on day 7 compared to the mock-infected. Cell fractionation and western blot analysis confirmed that Bag-1 isoform p32 was predominant in the cytoplasm of mouse myocardium and down-regulated at 4 days or 7 days after CVB3 infection. In contrast, Bag-1 isoform p50 appeared to increase in the nuclear fraction of mouse heart at 7 days after infection. Down regulated expression and distribution of Bag-1 protein or evidence of apoptosis in the infected mouse heart was demonstrated by immunostaining or histochemistry (TUNEL assay), respectively.


CONCLUSIONS
CVB3 infection induced differential expression of Bag-1 in cytoplasmic and nuclear fractions of mouse heart and apoptosis. This may be important in the pathogenesis of enterovirus heart muscle disease.
Key Laboratory of Viral Heart Disease of Ministry of Public Health, Shanghai Institute of Cardiovascular Disease, Zhongshan Hospital, Shanghai, PR China.
T
T
Peng
T
T
Sadusky
Y
Y
Li
G R
GR
Coulton
H
H
Zhang
L C
LC
Archard
D000818:Animals; D017209:Apoptosis; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism*; D003384:Coxsackievirus Infections / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D018076:DNA, Complementary / Q000235:genetics; D004268:DNA-Binding Proteins; D015536:Down-Regulation; D029822:Enterovirus B, Human; D020287:In Situ Nick-End Labeling; D008297:Male; D051379:Mice; D008815:Mice, Inbred Strains; D009205:Myocarditis / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D012333:RNA, Messenger / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014157:Transcription Factors
C091732:BCL2-associated athanogene 1 protein; D002352:Carrier Proteins; D018076:DNA, Complementary; D004268:DNA-Binding Proteins; D012333:RNA, Messenger; D014157:Transcription Factors