Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:2.7.11.22 (cdc2)
 8,319 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Earlier studies have shown that translation elongation factor 1delta (EF-1delta) is hyperphosphorylated in various mammalian cells infected with representative alpha-, beta-, and gammaherpesviruses and that the modification is mediated by conserved viral protein kinases encoded by herpesviruses, including UL13 of herpes simplex virus type 1 (HSV-1), UL97 of human cytomegalovirus, and BGLF4 of Epstein-Barr virus (EBV). In the present study, we attempted to identify the site in EF-1delta associated with the hyperphosphorylation by the herpesvirus protein kinases. Our results are as follows: (i) not only in infected cells but also in uninfected cells, replacement of the serine residue at position 133 (Ser-133) of EF-1delta by alanine precluded the posttranslational processing of EF-1delta, which corresponds to the hyperphosphorylation. (ii) A purified chimeric protein consisting of maltose binding protein (MBP) fused to a domain of EF-1delta containing Ser-133 (MBP-EFWt) is specifically phosphorylated in in vitro kinase assays by purified recombinant UL13 fused to glutathione S-transferase (GST) expressed in the baculovirus system. In contrast, the level of phosphorylation by the recombinant UL13 of MBP-EFWt carrying an alanine replacement of Ser-133 (MBP-EFS133A) was greatly impaired. (iii) MBP-EFWt is also specifically phosphorylated in vitro by purified recombinant BGLF4 fused to GST expressed in the baculovirus system, and the level of phosphorylation of MBP-EFS133A by the recombinant BGLF4 was greatly reduced. (iv) The sequence flanking Ser-133 of EF-1delta completely matches the consensus phosphorylation site for a cellular protein kinase, cdc2, and in vitro kinase assays revealed that purified cdc2 phosphorylates Ser-133 of EF-1delta. (v) As observed with EF-1delta, the casein kinase II beta subunit (CKIIbeta) was specifically phosphorylated by UL13 in vitro, while the level of phosphorylation of CKIIbeta by UL13 was greatly diminished when a serine residue at position 209, which has been reported to be phosphorylated by cdc2, was replaced with alanine. These results indicate that the conserved protein kinases encoded by herpesviruses and a cellular protein kinase, cdc2, have the ability to target the same amino acid residues for phosphorylation. Our results raise the possibility that the viral protein kinases mimic cdc2 in infected cells.
 ...
PMID:Conserved protein kinases encoded by herpesviruses and cellular protein kinase cdc2 target the same phosphorylation site in eukaryotic elongation factor 1delta. 1255 73

A subset (gamma(2)) of late herpes simplex virus 1 genes depends on viral DNA synthesis for its expression. For optimal expression, a small number of these genes, exemplified by U(S)11, also requires two viral proteins, the alpha protein infected cell protein (ICP) 22 and the protein kinase U(L)13. Earlier we showed that U(L)13 and ICP22 mediate the stabilization of cdc2 and the replacement of its cellular partner, cyclin B, with the viral DNA polymerase processivity factor U(L)42. Here we report that cdc2 and its new partner, U(L)42, bind a phosphorylated form of topoisomerase II alpha. The posttranslational modification of topoisomerase II alpha and its interaction with cdc2-U(L)42 proteins depend on ICP22 in infected cells. Although topoisomerase II is required for viral DNA synthesis, ICP22 is not, indicating a second function for topoisomerase II alpha. The intricate manner in which the virus recruits topoisomerase II alpha for post-DNA synthesis expression of viral genes suggests that topoisomerase II alpha also is required for untangling concatemeric DNA progeny for optimal transcription of late genes.
 ...
PMID:Herpes simplex virus 1 activates cdc2 to recruit topoisomerase II alpha for post-DNA synthesis expression of late genes. 1266 17

In herpes simplex virus 1-infected cells, a high level of alpha gene expression requires the transactivation of the genes by a complex containing the viral alpha transinducing factor (alphaTIF) and two cellular proteins. The latter two, HCF-1 and octamer binding protein Oct-1, are transcriptional factors regulated in a cell cycle-dependent manner. alphaTIF is a protein made late in infection but packaged with the virion to transactivate viral genes in newly infected cells. In light of the accumulation of large amounts of alphaTIF, the absence of alpha gene expression late in infection suggested the possibility that one or more transcriptional factors required for alpha gene expression is modified late in infection. Here we report that Oct-1 is posttranscriptionally modified late in infection, that the modification is mediated by the virus but does not involve viral protein kinases or cdc2 kinase activated by the virus late in infection, and that the modified Oct-1 has a reduced affinity for its cognate DNA site. These results are consistent with the hypothesis that modification of Oct-1 transcriptional factor could account at least in part for the shutoff of alpha gene expression late in infection.
 ...
PMID:Oct-1 is posttranslationally modified and exhibits reduced capacity to bind cognate sites at late times after infection with herpes simplex virus 1. 1458 29

The in vivo ganglionic environment directs the latent herpes simplex virus transcriptional program. Since stress-driven perturbations in sensory neurons are thought to play a critical role in the transition from latency to reactivation, a primary concern in the selection of a valid model of the molecular interactions leading to reactivation is the faithful recapitulation of these environments. In this study reactivation of latently infected ganglia excised and cultured in vitro (explanted) is compared to reactivation occurring in latently infected ganglia in vivo following hyperthermic stress. Three notable points emerged. (i). Neurons in explanted ganglia exhibited marked morphological changes within 2 to 3 h postexplant. DNA fragmentation in neuronal nuclei was detected at 3 h, and atypical expression of cell cycle- and stress-regulated proteins such as geminin, cdk2, cdk4, and cytochrome c became apparent at 2 to 48 h. These changes were associated with axotomy and explant and not with the initiation or progression of reactivation and were not observed in ganglia following in vivo hyperthermic stress. (ii). Despite these differences, during the first 22 h primary reactivation events were restricted to a very small number of neurons in vivo and in explanted ganglia. This suggests that at any given time only a few latently infected neurons are competent to reactivate or that the probability of reactivation occurring in any particular neuron is very low. Importantly, the marked changes detected in explanted ganglia were not correlated with increased reactivation, demonstrating that these changes were not associated with the reactivation process per se. (iii). Secondary spread of virus was evident in explanted ganglia within 36 h, an event not observed in vivo. We conclude that explant reactivation may provide an ancillary system for selected studies of the early events in reactivation. However, clear signs of neuronal degeneration within 2 to 3 h postexplant indicate that these ganglia are undergoing major physiological changes not associated with the reactivation process. This ongoing neurodegeneration could alter even the early virus-host interactions in reactivation, and thus caution in the extrapolation of results obtained in explants to the in vivo interactions initiating reactivation is warranted.
 ...
PMID:Comparison of herpes simplex virus reactivation in ganglia in vivo and in explants demonstrates quantitative and qualitative differences. 1522 Apr 52

The infected-cell protein 22 (ICP22), a regulatory protein encoded by the alpha22 gene of herpes simplex virus 1, is required for the optimal expression of a set of late viral proteins that includes the products of the U(S)11, U(L)38, and U(L)41 genes. ICP22 has two activities. Thus, ICP22 and the U(L)13 protein kinase mediate the activation of cdc2 and degradation of its partners, cyclins A and B. cdc2 and its new partner, the DNA polymerase accessory factor (U(L)42), bind topoisomerase IIalpha in an ICP22-dependent manner. In addition, ICP22 and U(L)13 mediate an intermediate phosphorylation of the carboxyl terminus of RNA polymerase II (RNA POL II). Here we report another function of ICP22. Thus, ICP22 physically interacts with cdk9, a constitutively active cyclin-dependent kinase involved in transcriptional regulation. A protein complex containing ICP22 and cdk9 phosphorylates in vitro the carboxyl-terminal domain of RNA POL II in a viral U(S)3 protein kinase-dependent fashion. Finally, the carboxyl-terminal domain of RNA POL II fused to glutathione S-transferase is phosphorylated in reaction mixtures containing complexes pulled down with ICP22 or cdk9 immune precipitated from lysates of wild-type parent virus or deltaU(L)13 but not deltaU(S)3 mutant-infected cells. The experiments described here place ICP22 and cdk9 in a complex with the carboxyl-terminal domain of RNA POL II. At the same time we confirm the requirement of ICP22 and the U(L)13 protein kinase in the posttranslational modification of RNA POL II that alters its electrophoretic mobility, although U(S)3 kinase appears to play a role in a cell-type-dependent fashion.
 ...
PMID:The carboxyl-terminal domain of RNA polymerase II is phosphorylated by a complex containing cdk9 and infected-cell protein 22 of herpes simplex virus 1. 1589 Sep 14

Herpes simplex virus 1 (HSV-1) ICP27 has been shown to interact with RNA polymerase II (RNAP II) holoenzyme. Here, we show that ICP27 interacts with the C-terminal domain (CTD) of RNAP II and that ICP27 mutants that cannot interact fail to relocalize RNAP II to viral transcription sites, suggesting a role for ICP27 in RNAP II recruitment. Using monoclonal antibodies specific for different phosphorylated forms of the RNAP II CTD, we found that the serine-2 phosphorylated form, which is found predominantly in elongating complexes, was not recruited to viral transcription sites. Further, there was an overall reduction in phosphoserine-2 staining. Western blot analysis revealed that there was a pronounced decrease in the phosphoserine-2 form and in overall RNAP II levels in lysates from cells infected with wild-type HSV-1. There was no appreciable difference in cdk9 levels, suggesting that protein degradation rather than dephosphorylation was occurring. Treatment of infected cells with proteasome inhibitors MG-132 and lactacystin prevented the decrease in the phosphoserine-2 form and in overall RNAP II levels; however, there was a concomitant decrease in the levels of several HSV-1 late proteins and in virus yield. Proteasomal degradation has been shown to resolve stalled RNAP II complexes at sites of DNA damage to allow 3' processing of transcripts. Thus, we propose that at later times of infection when robust transcription and DNA replication are occurring, elongating complexes may collide and proteasomal degradation may be required for resolution.
 ...
PMID:ICP27 interacts with the C-terminal domain of RNA polymerase II and facilitates its recruitment to herpes simplex virus 1 transcription sites, where it undergoes proteasomal degradation during infection. 1653 25

Since the 1950's, herpes simplex viruses (HSV) have played prominent roles in the development of antivirals. The first efficacious antivirals, as well as the first safe for systemic use, were developed against HSV. It was only in 1995 when the first antiviral against a target not validated first with HSV was approved for clinical use (sequinavir). The early successes of targeting HSV DNA replication were most influential in developing the concept that antiviral drugs must target viral proteins. Such concept has ensured the safety of current antiviral drugs, which all target viral proteins. Current antivirals have proven to have no major negative effects on non-infected cells or treated patients. Because of their success widespread and use, however, these drugs have been found to have some limitations. Perhaps the clinically most important one is their ability to promptly select for drug-resistant viral strains. Owing to such limitations, cellular proteins are now considered as valid targets for novel antiviral drugs. The discovery that pharmacological CDK inhibitors (PCIs) inhibit HSV replication through novel mechanisms played a major role in this new appreciation of cellular proteins as potential targets for antivirals. This appreciation is reflected in the scheduling of PCIs to enter clinical trials as antivirals (against HIV). Herein, we will review the roles of HSV as model viruses in the discovery and development of antiviral drugs. The major focus will be on the recent discovery on the activities of PCIs against HSV and other viruses.
 ...
PMID:Herpes simplex viruses in antiviral drug discovery. 1661 Nov 20

Herpesviral protein kinases of the UL97 subfamily are expressed by all known herpesviruses but the degree of functional conservation is unclear. A selection of representative members was investigated by a comparative structural and functional analysis. The coding sequences of human cytomegalovirus (HCMV) pUL97, rat CMV pR97, Epstein-Barr virus BGLF4, and herpes simplex virus UL13 showed a low degree of amino acid identity. A computational approach employing fold recognition techniques revealed structural similarity to the cellular kinase Cdk2 with a high level of conservation of the functionally important residues in ATP binding sites and the catalytic centers. Analyses of in vitro activities of these herpesviral protein kinases, including measurements of phosphorylation of cellular substrates, trans-complementation experiments with a UL97-deleted HCMV mutant, and sensitivity profiles toward protein kinase inhibitors, demonstrated marked similarities between pUL97 and pR97 and to a lesser extent between pUL97 and BGLF4 or UL13. Thus, the structure-activity analysis of pUL97-like herpesviral protein kinases indicates a partial but not a full conservation of their functional properties among the herpesviruses.
 ...
PMID:Analysis of the structure-activity relationship of four herpesviral UL97 subfamily protein kinases reveals partial but not full functional conservation. 1712 57

Earlier studies have shown that ICP22 and the U(L)13 protein kinase but not the U(S)3 kinase are required for optimal expression of a subset of late (gamma(2)) genes exemplified by U(L)38, U(L)41, and U(S)11. In primate cells, ICP22 mediates the disappearance of inactive isoforms of cdc2 and degradation of cyclins A and B1. Active cdc2 acquires a new partner, the viral DNA synthesis processivity factor U(L)42. The cdc2-U(L)42 complex recruits and phosphorylates topoisomerase IIalpha for efficient expression of the gamma(2) genes listed above. In uninfected cells, the cdc25C phosphatase activates cdc2 by removing two inhibitory phosphates. The accompanying report shows that in the absence of cdc25C, the rate of degradation of cyclin B1 is similar to that occurring in infected wild-type mouse embryo fibroblast cells but the levels of cdc2 increase, and the accumulation of a subset of late proteins and virus yields are reduced. This report links ICP22 with cdc25C. We show that in infected cells, ICP22 and U(S)3 protein kinase mediate the phosphorylation of cdc25C at its C-terminal domain. In in vitro assays with purified components, both U(L)13 and U(S)3 viral kinases phosphorylate cdc25C and ICP22. cdc25C also interacts with cdc2. However, in infected cells, the ability of cdc25C to activate cdc2 by dephosphorylation of the inactive cdc2 protein is reduced. Coupled with the phosphorylation of cdc25C by the U(S)3 kinase, the results raise the possibility that herpes simplex virus 1 diverts cdc25C to perform functions other than those performed in uninfected cells.
 ...
PMID:The interaction of herpes simplex virus 1 regulatory protein ICP22 with the cdc25C phosphatase is enabled in vitro by viral protein kinases US3 and UL13. 1827 72

Earlier studies have shown that in herpes simplex virus 1-infected cells, ICP22 upregulates the accumulation of a subset of gamma(2) proteins exemplified by the products of the U(L)38, U(L)41, and U(S)11 genes. The ICP22-dependent process involves degradation of cyclins A and B1, the stabilization and activation of cdc2, physical interaction of activated cdc2 with the U(L)42 DNA synthesis processivity factor, and recruitment and phosphorylation of topoisomerase IIalpha by the cdc2/U(L)42 complex. Activation of cdc2, the first step in the process, is a key function of the mitotic phosphatase cdc25C. To define the role of cdc25C, we probed some features of the ICP22-dependent pathway of upregulation of gamma(2) genes in cdc25C(-/-) cells and in cdc25C(+/+) cells derived from sibling mice. We report that cyclin B1 turned over in cdc25C(+/+) or cdc25C(-/-) cells at the same rate, that cdc2 increased in amount, and that U(S)11 and U(L)38 proteins and infectious virus accumulated in smaller amounts than in wild-type infected cells. The reduction in U(L)38 protein accumulation and virus was greater in cdc25C(-/-) cells infected with virus lacking ICP22 than in cells infected with wild-type virus. We conclude that cdc25C phosphatase plays a role in viral replication and that this role extends beyond its function of activating cdc2 for initiation of the ICP22-dependent cascade for upregulation of gamma(2) gene expression.
 ...
PMID:Role of cellular phosphatase cdc25C in herpes simplex virus 1 replication. 1827 75


<< Previous 1 2 3 Next >>