Baculovirus p33 Binds Human p53 and Enhances p53-Mediated Apoptosis

Abstract

In vertebrates, p53 participates in numerous biological processes including cell cycle regulation, apoptosis, differentiation, and oncogenic transformation. When insect SF-21 cells were infected with a recombinant of the baculovirus Autographa californicanuclear polyhedrosis virus (AcMNPV) overexpressing human p53, p53 formed a stable complex with the product of the AcMNPV orf92, a novel protein p33. The interaction between p53 and p33 was further confirmed by immunoprecipitation studies. When individually expressed in SF-21 cells, human p53 localized mainly in the nucleus whereas baculovirus p33 displayed diffuse cytoplasmic staining and punctuate nuclear staining. However, coexpression of p33 with p53 resulted in exclusive nuclear localization of p33. In both SF-21 and TN-368 cells, p53 expression induced typical features of apoptosis including nuclear condensation and fragmentation, oligonucleosomal ladder formation, cell surface blebbing, and apoptotic body formation. Coexpression of p53 with a baculovirus inhibitor of apoptosis, p35, OpIAP, or CpIAP, blocked apoptosis, whereas coexpression with p33 enhanced p53-mediated apoptosis approximately twofold. Expression of p53 in SF-21 cells stably expressing OpIAP inhibited cell growth in the presence or absence of p33. Thus, human p53 can influence both insect cell growth and death and baculovirus p33 can modulate the death-inducing effects of p53.

The Baculoviruses Occlusion‐Derived Virus: Virion Structure and Function

“…The nucleocapsid-associated baculovirus protein P33 may be involved in apoptosis given that this protein binds to murine or human p53 (Prikhod'ko et al, 1999b). The cellular p53 protein is involved in apoptosis and cell cycle regulation (for review see Bai et al, 2005;Collot-Teixeira et al, 2004).…”

“…The cellular p53 protein is involved in apoptosis and cell cycle regulation (for review see Bai et al, 2005;Collot-Teixeira et al, 2004). Cosynthesis of P33 with the cellular protein p53 in insect cells leads to apoptosis (Prikhod'ko et al, 1999b). The P33 protein appears essential for baculovirus infection (Prikhod'ko et al, 1999b), and existence of an insect homologue to p53 (Jin et al, 2000) leads to the possibility that P33 is involved in mechanisms which target p53 in order to inhibit apoptosis or permit cell cycle progression.…”

“…Cosynthesis of P33 with the cellular protein p53 in insect cells leads to apoptosis (Prikhod'ko et al, 1999b). The P33 protein appears essential for baculovirus infection (Prikhod'ko et al, 1999b), and existence of an insect homologue to p53 (Jin et al, 2000) leads to the possibility that P33 is involved in mechanisms which target p53 in order to inhibit apoptosis or permit cell cycle progression. P53 is a DNA-binding protein and it is possible that P33 associates with host P53 proteins on the viral genome in nucleocapsids.…”

Comparative characterization of cell death between Sf9 insect cells and hybridoma cultures

“…Compared to other commercially important cell lines, information on PCD in insect cell culture is less abundant and usually limited to qualitative observations. Most studies have centered on understanding the molecular mechanisms of PCD during culture infection by baculovirus (Clem et al, 1991;Prikhod'Ko et al, 1999). In general, such reports lack detailed quantitative information of insect cell death kinetics and only indicate whether apoptosis is present or not.…”

“…In general, such reports lack detailed quantitative information of insect cell death kinetics and only indicate whether apoptosis is present or not. Internucleosomal DNA fragmentation by analysis on agarose gel electrophoresis is usually employed for determining PCD in insect cell culture (Clem et al, 1991;Prikhod'Ko et al, 1999). However, such an assay is laborious, timeconsuming, can yield false negatives or positives, and presents other drawbacks that impede quantitative determinations (Cohen et al, 1992;Collins et al, 1992;Duke and Cohen, 1995).…”