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Classic swine fever virus NS2 protein leads to the induction of cell cycle arrest at S-phase and endoplasmic reticulum stress.

Tang QH, Zhang YM, Fan L, Tong G, He L, Dai C - Virol. J. (2010)

Bottom Line: A significant increase in cyclin A transcriptional levels was observed in NS2-expressing cells but was accompanied by a concomitant increase in the proteasomal degradation of cyclin A protein.Therefore, the induction of cell cycle arrest at S-phase by CSFV NS2 protein is associated with increased turnover of cyclin A protein rather than the down-regulation of cyclin A transcription.These findings provide novel information on the function of the poorly characterized CSFV NS2 protein.

View Article: PubMed Central - HTML - PubMed

Affiliation: College of Veterinary Medicine, Northwest A & F University, Yangling, Shaanxi, China.

ABSTRACT

Background: Classical swine fever (CSF) caused by virulent strains of Classical swine fever virus (CSFV) is a haemorrhagic disease of pigs, characterized by disseminated intravascular coagulation, thrombocytopoenia and immunosuppression, and the swine endothelial vascular cell is one of the CSFV target cells. In this report, we investigated the previously unknown subcellular localization and function of CSFV NS2 protein by examining its effects on cell growth and cell cycle progression.

Results: Stable swine umbilical vein endothelial cell line (SUVEC) expressing CSFV NS2 were established and showed that the protein localized to the endoplasmic reticulum (ER). Cellular analysis revealed that replication of NS2-expressing cell lines was inhibited by 20-30% due to cell cycle arrest at S-phase. The NS2 protein also induced ER stress and activated the nuclear transcription factor kappa B (NF-kappaB). A significant increase in cyclin A transcriptional levels was observed in NS2-expressing cells but was accompanied by a concomitant increase in the proteasomal degradation of cyclin A protein. Therefore, the induction of cell cycle arrest at S-phase by CSFV NS2 protein is associated with increased turnover of cyclin A protein rather than the down-regulation of cyclin A transcription.

Conclusions: All the data suggest that CSFV NS2 protein modulate the cellular growth and cell cycle progression through inducing the S-phase arrest and provide a cellular environment that is advantageous for viral replication. These findings provide novel information on the function of the poorly characterized CSFV NS2 protein.

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Cell proliferation assays of stable NS2-expressing cell lines. The MTS assay was used to measure proliferation of 4 × 103 cells from SUVEC cell lines over time. Each data set represents the mean ± S.D. of six replicates.
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Figure 2: Cell proliferation assays of stable NS2-expressing cell lines. The MTS assay was used to measure proliferation of 4 × 103 cells from SUVEC cell lines over time. Each data set represents the mean ± S.D. of six replicates.

Mentions: Compared with control cells (pEGFP-C1 transfected and untransfected), the CSFV NS2 expressing cells divided much more slowly leading to a significantly decreased cell number after a period of time. Cell proliferation of NS2 expressing cells measured by the MTS assay was decreased by approximately 20 - 30% over a time course of 72 to 96 h (Fig. 2).


Classic swine fever virus NS2 protein leads to the induction of cell cycle arrest at S-phase and endoplasmic reticulum stress.

Tang QH, Zhang YM, Fan L, Tong G, He L, Dai C - Virol. J. (2010)

Cell proliferation assays of stable NS2-expressing cell lines. The MTS assay was used to measure proliferation of 4 × 103 cells from SUVEC cell lines over time. Each data set represents the mean ± S.D. of six replicates.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2819037&req=5

Figure 2: Cell proliferation assays of stable NS2-expressing cell lines. The MTS assay was used to measure proliferation of 4 × 103 cells from SUVEC cell lines over time. Each data set represents the mean ± S.D. of six replicates.
Mentions: Compared with control cells (pEGFP-C1 transfected and untransfected), the CSFV NS2 expressing cells divided much more slowly leading to a significantly decreased cell number after a period of time. Cell proliferation of NS2 expressing cells measured by the MTS assay was decreased by approximately 20 - 30% over a time course of 72 to 96 h (Fig. 2).

Bottom Line: A significant increase in cyclin A transcriptional levels was observed in NS2-expressing cells but was accompanied by a concomitant increase in the proteasomal degradation of cyclin A protein.Therefore, the induction of cell cycle arrest at S-phase by CSFV NS2 protein is associated with increased turnover of cyclin A protein rather than the down-regulation of cyclin A transcription.These findings provide novel information on the function of the poorly characterized CSFV NS2 protein.

View Article: PubMed Central - HTML - PubMed

Affiliation: College of Veterinary Medicine, Northwest A & F University, Yangling, Shaanxi, China.

ABSTRACT

Background: Classical swine fever (CSF) caused by virulent strains of Classical swine fever virus (CSFV) is a haemorrhagic disease of pigs, characterized by disseminated intravascular coagulation, thrombocytopoenia and immunosuppression, and the swine endothelial vascular cell is one of the CSFV target cells. In this report, we investigated the previously unknown subcellular localization and function of CSFV NS2 protein by examining its effects on cell growth and cell cycle progression.

Results: Stable swine umbilical vein endothelial cell line (SUVEC) expressing CSFV NS2 were established and showed that the protein localized to the endoplasmic reticulum (ER). Cellular analysis revealed that replication of NS2-expressing cell lines was inhibited by 20-30% due to cell cycle arrest at S-phase. The NS2 protein also induced ER stress and activated the nuclear transcription factor kappa B (NF-kappaB). A significant increase in cyclin A transcriptional levels was observed in NS2-expressing cells but was accompanied by a concomitant increase in the proteasomal degradation of cyclin A protein. Therefore, the induction of cell cycle arrest at S-phase by CSFV NS2 protein is associated with increased turnover of cyclin A protein rather than the down-regulation of cyclin A transcription.

Conclusions: All the data suggest that CSFV NS2 protein modulate the cellular growth and cell cycle progression through inducing the S-phase arrest and provide a cellular environment that is advantageous for viral replication. These findings provide novel information on the function of the poorly characterized CSFV NS2 protein.

Show MeSH
Related in: MedlinePlus