1. Human parvovirus B19 non-structural protein (NS1) induces apoptosis through mitochondria cell death pathway in COS-7 cells
- Author
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Meng-Chi Chen, Wen-Jun Wu, Gregory J. Tsay, and Tsai-Ching Hsu
- Subjects
Microbiology (medical) ,Programmed cell death ,viruses ,Blotting, Western ,Molecular Sequence Data ,Apoptosis ,Caspase 3 ,Viral Nonstructural Proteins ,Transfection ,Sensitivity and Specificity ,Sampling Studies ,Western blot ,Parvovirus B19, Human ,medicine ,Animals ,Humans ,Cells, Cultured ,Caspase-9 ,Base Sequence ,Cell Death ,General Immunology and Microbiology ,biology ,medicine.diagnostic_test ,Reverse Transcriptase Polymerase Chain Reaction ,Kinase ,virus diseases ,General Medicine ,Cell cycle ,Molecular biology ,Mitochondria ,Infectious Diseases ,Microscopy, Fluorescence ,Caspases ,COS Cells ,biology.protein - Abstract
Human parvovirus B19 has been found in various tissues in addition to erythroid lineage cells, and non-structural protein (NS1) is reported to induce cytotoxicity and apoptosis in erythroid lineage cells, but the mechanism in non-permissive cells is still unclear. To address this issue, we have constructed the NS1 gene in a cytomegalovirus episomal vector, pEGFP-C1 and transfected it into monkey epithelial cells, COS-7. EGFP-NS1 expression in transfected cells was monitored and assessed by fluorescence microscopy, RT-PCR and Western blot. The flow cytometric analysis showed that the NS1-transfected cells were arrested at G1 phase by paclitaxel treatment and there was increased apoptosis. The expression of p53, an important molecule in apoptosis and cell cycle regulation, and its downstream cell cycle kinase inhibitors p16(INK4) and p21(WAF1/CIP1) were up-regulated in the NS1-transfected cells. Also, increased expression of the pro-apoptotic Bcl-2 members Bax, Bad and activation of caspase 3 and caspase 9, but not the activation of caspase 8 or Fas were detected in the NS1-transfected cells. p53-induced Bax expression and subsequent activation of caspase 9 is probably the apoptotic pathway in NS1-transfected cells since activation of the caspase 9 was suppressed by the p53 inhibitor and apoptosis was significantly inhibited by the caspase 9 inhibitor. Our results suggest that the cell death of the NS1-transfected cells is associated with mitochondria related apoptosis. These findings might provide alternative information for further study and characterization of B19 NS1 protein in B19 non-permissive cells.
- Published
- 2004