Cellular protein kinase C isoform zeta regulates human parainfluenza virus type 3 replication.

Abstract

Human parainfluenza viruses (HPIVs) are members of the paramyxovirus family (1, 2). Understanding the molecular events that control HPIV replication is particularly important because they are significant human pathogens causing diseases such as croup, pneumonia, and bronchiolotis in children (3). No suitable vaccines are currently available for these classes of viruses. HPIV type 3 (HPIV3), most pathogenic among the HPIVs, contains a linear genomic RNA (15,461 nt) of negative polarity and three structural proteins, NP (68-kDa nucleocapsid protein), L (251-kDa large protein), and P (90-kDa phosphoprotein), all ofwhich are enclosed within a lipid-containing envelope (1, 2). The L and P proteins together constitute the viral RNA-dependent RNA polymerase complex that, similar to that of other paramyxoviruses, transcribes the NP-bound genomic RNA (4-6); L is the RNA polymerase, whereas P is a required transcription factor or transactivator of L. Host cytoskeletal proteins can act as positive regulators in viral mRNA synthesis-e.g., actin in HPIV3 (7) or tubulin in Sendai and measles viruses (8, 9).Phosphorylation of the P proteins of nonsegmented negative-strand RNA viruses is believed to be mediated by cellular protein kinases and is an important step in the formation of the active RNA polymerase complex (10-12). Cellular casein kinase II (CKII) has been implicated in phosphorylation of P proteins of vesicular stomatitis virus (VSV) (10) and respiratory syncytial virus (11,12). In the well-studied VSV system, use of unphosphorylated P protein (Po) obtained from a cDNA-derived expression in Escherichia coli has demonstrated that a cascade phosphorylation pathway is operative for Pprotein activation in vitro (13). The first step in the pathway is the phosphorylation mediated by cellular CKII, leading to aThe publication costs of this article were defrayed in part by page charge payment. This article must therefore be hereby marked "advertisement" in accordance with 18 U.S.C. §1734 solely to indicate this fact. structural alteration of the P protein (P1 form). The second step involves further phosphorylation of P1 by the protein kinase activity associated with the L protein, leading to the formation of the fully phosphorylated P2 form. This phosphorylation pathway is obligatory for the activation of P protein to function in the RNA polymerase complex. Here we report that HPIV3, in contrast, selects a specific isoform (C) of cellular protein kinase C (PKC-C) for phosphorylation of its P protein and also packages the same isoform within the virion.

Roles of Serine and Threonine Residues of Mumps Virus P Protein in Viral Transcription and Replication

“…CKII is thought to phosphorylate the P proteins of respiratory syncytial virus (RSV) (19,20) and measles virus (21). PKC-is reported to phosphorylate the P proteins of human parainfluenza virus 3 (HPIV3) (22) and Sendai virus (23). The P protein of canine distemper virus is phosphorylated by both PKC-and CKII (24).…”

Specific Phosphorylated Forms of Glyceraldehyde 3-Phosphate Dehydrogenase Associate with Human Parainfluenza Virus Type 3 and Inhibit Viral Transcription In Vitro

“…In vitro phosphorylation of GAPDH and La protein was performed using rat brain protein kinase (PKC) and recombinant CKII as described previously (2,10).…”

Interferon Action against Human Parainfluenza Virus Type 3: Involvement of a Novel Antiviral Pathway in the Inhibition of Transcription

“…The cells were treated with IFN at the concentrations indicated in individual experiments for 12 h and then infected with HPIV3 at multiplicities of infection (MOI) indicated in individual experiments. Culture supernatants were collected at 40 h postinfection, unless otherwise stated, and the infectious virus yield was measured by plaque assay on CV-1 cells (8).…”