Activation of the intrinsic mitochondrial apoptotic pathway in swine influenza virus-mediated cell death.
The mitochondrial pathway of swine influenza virus (SIV)-induced apoptosis was investigated using porcine kidney (PK-15) cells, swine testicle (ST) cells, and HeLa cervical carcinoma cells which are known not to support viral replication. As judged by cell morphology, annexin V staining, and DNA fragmentation, PK-15 and ST cells infected with three different subtypes of SIV (H1N1, H3N2, and H1N2) were obviously killed by apoptosis, not necrosis. SIV infection in PK-15 and HeLa cells was shown to decrease the cellular levels of Bcl-2 protein compared to that of mock-infected control cells at 24 h post-infection, whereas expression levels of Bax protein increased in the PK-15 cells, but did not increase in HeLa cells by SIV infection. Cytochrome c upregulation was also observed in cytosolic fractions of the PK-15 and HeLa cells infected with SIV. Apoptosome (a multi-protein complex consisting of cytochrome c, Apaf-1, caspase-9, and ATP) formation was confirmed by immunoprecipitation using cytochrome c antibody. Furthermore, SIV infection increased the cellular levels of TAJ, an activator of the JNK- stressing pathway, and the c-Jun protein in the PK-15 and HeLa cells. Taken together, these results suggest that the mitochondrial pathway should be implicated in the apoptosis of PK-15 cells induced by SIV infection.
Choi
Young Ki
YK
College of Medicine and Medical Research Institute, Chungbuk National University, Cheongju 361-711, Korea.
Kim
Tae-Kyung
TK
Kim
Chul-Joong
CJ
Lee
Joong-Seob
JS
Oh
Se-Young
SY
Joo
Han Soo
HS
Foster
Douglas N
DN
Hong
Ki-Chang
KC
You
Seungkwon
S
Kim
Hyunggee
H
D000818:Animals; D017304:Annexin A5 / Q000378:metabolism; D017209:Apoptosis; D015153:Blotting, Western; D002458:Cell Fractionation; D002460:Cell Line; D003574:Cytochrome c Group / Q000378:metabolism; D003600:Cytosol / Q000737:chemistry; D053938:DNA Fragmentation; D004789:Enzyme Activation; D015967:Gene Expression Regulation, Viral; D006367:HeLa Cells; D006801:Humans; D009980:Influenza A virus / Q000502:physiology*; D007700:Kinetics; D008928:Mitochondria / Q000378:metabolism / Q000502:physiology*; D011233:Precipitin Tests; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000235:genetics / Q000378:metabolism; D013552:Swine; D051028:bcl-2-Associated X Protein / Q000235:genetics / Q000378:metabolism
D017304:Annexin A5; D003574:Cytochrome c Group; D019253:Proto-Oncogene Proteins c-bcl-2; D051028:bcl-2-Associated X Protein