p21(Waf1/Cip1) as a molecular sensor for BoHV-4 replication
ABSTRACT BoHV-4 replication cycle is dependent on the S-phase of the cell-cycle at the stage of viral DNA synthesis. Because p21 is a rate-limiting regulator of the G1/S-phase transition and up-regulated by DNA-damaging agents, in this study p21 expression in BoHV-4 infected cells was investigated. The p21 promoter was found to be highly activated in a dose- and time-dependent manner following BoHV-4 infection only in cells which are permissive for BoHV-4 replication. Thus p21 expression reports on BoHV-4 replication and could represent a host cell defensive response to infection-associated cellular damage.
- SourceAvailable from: Serena Montagnaro[Show abstract] [Hide abstract]
ABSTRACT: Bovine Herpesvirus type 4 (BoHV-4), like other herpesviruses, induces a series of alterations in the host cell that modify the intracellular environment in favour of viral replication, survival and spread. This research examined the impact of BoHV-4 infection on autophagy in BoHV-4 infected Madin Darby Bovine Kidney (MDBK) cells. Protein extracts of BoHV-4 infected and control MDBK cells were subjected to western blot. The concentrations of the autophagy and apoptosis-related proteins Beclin 1, p21, PI3 Kinase, Akt1/2, mTOR, phospho mTOR, p62 and the light chain three (LC3) were normalised to the actin level and expressed as the densitometric ratio. Western blot analysis of virus-infected cells revealed that autophagic degradation pathway was induced in the late phase of BoHV-4 infection. After 48 hours post infection the protein LC3II, which is essential for autophagy, was found to be markedly increased, while infection of MDBK cells with BoHV-4 resulted in a depletion of p62 levels. Becline 1, PI3 Kinase, Akt1/2 and p21 expression increased between 24 and 48 h post infection. Surprisingly, mTOR and its phosphorylated form, which are negative regulators of autophagy, also increased after 24 hours post infection. In conclusion, our findings suggest that BoHV-4 has developed mechanisms for modulation of autophagy that are probably part of a strategy designed to enhance viral replication and to evade the immune system. Additional studies on the relationship between autophagy and BoHV-4 replication and survival, in both lytic and latent replication phases, are needed to understand the role of autophagy in BoHV-4 pathogenesis. J. Cell. Biochem. © 2013 Wiley Periodicals, Inc.Journal of Cellular Biochemistry 07/2013; 114(7). DOI:10.1002/jcb.24494 · 3.37 Impact Factor
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ABSTRACT: Throughout development cells make the decision to proliferate, arrest or die. Control of this process is essential for normal development, with unrestrained cell proliferation and cell death underlying the origin and progression of disease. The cell-cycle is tightly regulated by a number of factors including the cyclin-dependent kinase inhibitor 1A (Cdkn1a), termed p21 (or Cip1 or WAF1). p21 acts as a negative regulator of cell-cycle progression by binding and inhibiting complexes formed between the cyclin-dependent kinases and their catalytic partners the cyclins. In this report we identify the temporal spatial expression profile of p21 in the developing mid-term mouse embryo using a p21-LacZ reporter mouse line. Expression of p21 was restricted to specific regions with a correspondence to both areas of terminal differentiation and active remodelling. A complex temporal and spatial relationship between p21 expression and regions of apoptosis was evident. A protective role with regard to apoptosis for p21 is proposed.Transgenic Research 03/2010; 20(1):23-8. DOI:10.1007/s11248-010-9385-6 · 2.28 Impact Factor
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ABSTRACT: Cellular p53 and its downstream mediator p21, the major cellular growth suppression and DNA repair markers, have recently been implicated in viral amplification. Here, we show that herpes simplex virus type 2 (HSV-2) infection of both HCT116 p53(+/+)and NIH3T3 cells resulted in sustained increases of p21. HSV-2 infection did not increase cellular p53 expression, but led to phosphorylation of this protein at Ser20. This phosphorylation was accompanied by the increase of p21 protein levels. Furthermore, specific knockdown of endogenous p21 by siRNAs severely impaired virus production represented by HSV envelope glycoprotein B (gB) expression and progeny virus titers. Disruption of the p53-p21 pathway by either knocking down p53 in HCT116 p53(+/+) and NIH3T3 cells or using p53-deficient HCT116 p53(-/-) cells, led to a significant reduction of HSV-2 production. Together, these results suggest that the p53-p21 pathway is required for efficient HSV-2 lytic replication cycle. Because HSV infection induces the G0/G1 phase arrest at the early step of lytic-replication cycle, we propose that HSV-2 might hijack the cellular p53-p21 pathway to arrest the host cell cycle at G0/G1 phase, blocking cellular DNA synthesis, for its own benefit, i.e., to favor its own viral replication by avoiding competition in generating viral nucleotide pools.Virus Research 07/2012; 169(1):91-7. DOI:10.1016/j.virusres.2012.07.011 · 2.83 Impact Factor