Translational Inhibition in Vitro of Human Papillomavirus Type 16 L2 mRNA Mediated through Interaction with Heterogenous Ribonucleoprotein K and Poly(rC)-binding Proteins 1 and 2

Human papillomavirus (HPV) type 16 belongs to the group of “high risk” HPV types that are frequently detected in anogenital cancers. The expression of HPV-16 late genes encoding the virus capsid proteins L1 and L2 is restricted to terminally differentiated epithelial cells in the superficial layers of the squamous epithelium. We have previously identified negative elements in the 3′ end of L2 RNA that act in cis to reduce mRNA utilization without substantially affecting mRNA levels. The experiments reported here demonstrate the interaction of cellular proteins with an inhibitory sequence present in the coding region of the L2 mRNA. Using RNA gel shift assays and UV cross-linking, we have detected three cellular proteins interacting specifically with the sense strand of the L2 mRNA, two of which were identified as heterogeneous ribonucleoprotein K (hnRNP K) and the poly(rC) binding- protein (PCBP). Recombinant hnRNP K, PCBP-1, and PCBP-2 that were over expressed in bacteria and partially purified bound to the HPV-16 L2 mRNA in a sequence-specific manner. Interestingly, PCBP-1, PCBP-2, and hnRNP K specifically and efficiently inhibited translation of the HPV-16 L2 mRNA in vitro. Therefore, these proteins may play an important role in the regulation of HPV-16 late gene expression and virus production in vivo. Human papillomavirus (HPV) type 16 belongs to the group of “high risk” HPV types that are frequently detected in anogenital cancers. The expression of HPV-16 late genes encoding the virus capsid proteins L1 and L2 is restricted to terminally differentiated epithelial cells in the superficial layers of the squamous epithelium. We have previously identified negative elements in the 3′ end of L2 RNA that act in cis to reduce mRNA utilization without substantially affecting mRNA levels. The experiments reported here demonstrate the interaction of cellular proteins with an inhibitory sequence present in the coding region of the L2 mRNA. Using RNA gel shift assays and UV cross-linking, we have detected three cellular proteins interacting specifically with the sense strand of the L2 mRNA, two of which were identified as heterogeneous ribonucleoprotein K (hnRNP K) and the poly(rC) binding- protein (PCBP). Recombinant hnRNP K, PCBP-1, and PCBP-2 that were over expressed in bacteria and partially purified bound to the HPV-16 L2 mRNA in a sequence-specific manner. Interestingly, PCBP-1, PCBP-2, and hnRNP K specifically and efficiently inhibited translation of the HPV-16 L2 mRNA in vitro. Therefore, these proteins may play an important role in the regulation of HPV-16 late gene expression and virus production in vivo. Human papillomaviruses (HPVs) 1The abbreviations used are: HPVhuman papillomavirushnRNP Kheterogenous ribonucleoprotein KPCBP-1poly(rC)-binding-protein 1PCBP-2poly(rC)-binding protein 2GSTglutathione S-transferaseCATchloramphenicol acetyltransferaseELISAenzyme-linked immunosorbent assay.1The abbreviations used are: HPVhuman papillomavirushnRNP Kheterogenous ribonucleoprotein KPCBP-1poly(rC)-binding-protein 1PCBP-2poly(rC)-binding protein 2GSTglutathione S-transferaseCATchloramphenicol acetyltransferaseELISAenzyme-linked immunosorbent assay. are nonenveloped, epitheliotropic DNA tumor viruses with a circular double-stranded genome of approximately 8 kilobases (1Howley P.M. Fields B.N. Knipe D.M. Howley P.M. Fields Virology. 3rd Ed. 2. Lippincott-Raven, Philadelphia1996: 2045-2076Google Scholar). At present more than 70 different types of HPVs have been identified that can be divided into mucosal or cutaneous types on the basis of the epithelium they infect (2Billakanti S.R. Calef C.E. Farmer A.D. Halpern A.L. Myers G.L. Human Papillomaviruses: A Compilation and Analysis of Nucleic Acid and Amino Acid Sequences (Theoretical Biology and Biophysics). Los Alamos National Laboratory, Los Alamos, NM1996Google Scholar). The major stimulus for current interest in the HPV group originates from the discovery of the casual relationship to carcinoma of the cervix of certain HPV types, primarily types 16 and 18 (3zur Hausen H. Biochim. Biophys. Acta. 1996; 1288: 55-78Crossref PubMed Scopus (1468) Google Scholar, 4Shah K.V. Howley P.M. Fields B.N. Knipe D.M. Howley P.M. Fields Virology. 3rd Ed. 2. Lippincott-Raven, Philadelphia1996: 2077-2109Google Scholar). The genomic organization of the various HPV types is very similar. All of the open reading frames are located on one strand of viral genomic DNA that consists of an early, a late, and a noncoding region (1Howley P.M. Fields B.N. Knipe D.M. Howley P.M. Fields Virology. 3rd Ed. 2. Lippincott-Raven, Philadelphia1996: 2045-2076Google Scholar). Early genes are expressed throughout the infected epithelium and are responsible for initiation of viral DNA replication, regulation of transcription, and transformation of cells (1Howley P.M. Fields B.N. Knipe D.M. Howley P.M. Fields Virology. 3rd Ed. 2. Lippincott-Raven, Philadelphia1996: 2045-2076Google Scholar, 5Chow L.T. Broker T.R. Intervirology. 1994; 37: 150-158Crossref PubMed Scopus (119) Google Scholar, 6Laimins L.A. Infect. Agents Dis. 1993; 2: 74-86PubMed Google Scholar, 7Meyers C. Laimins L.A. Lacey C. Papillomavirus Reviews: Current Research on Papillomaviruses. Leeds University Press, 1996: 79-83Google Scholar, 8Stanley M.A. Antivir. Res. 1994; 24: 1-15Crossref PubMed Scopus (33) Google Scholar, 9Hagensee M.E. Galloway D.A. Lacey C. Papillomavirus Reviews: Current Research on Papillomaviruses. Leeds University Press, 1996: 85-92Google Scholar). The late genes code for the major and minor capsid proteins, L1 and L2, respectively, and their expression is thought to be regulated at both the transcriptional and the post-transcriptional level. Production of L1 and L2 protein is seen to be inhibited in dividing cells, and the L1 and L2 proteins are detected primarily in the superficial layers of terminally differentiated squamous epithelial cells (1Howley P.M. Fields B.N. Knipe D.M. Howley P.M. Fields Virology. 3rd Ed. 2. Lippincott-Raven, Philadelphia1996: 2045-2076Google Scholar, 5Chow L.T. Broker T.R. Intervirology. 1994; 37: 150-158Crossref PubMed Scopus (119) Google Scholar, 6Laimins L.A. Infect. Agents Dis. 1993; 2: 74-86PubMed Google Scholar, 7Meyers C. Laimins L.A. Lacey C. Papillomavirus Reviews: Current Research on Papillomaviruses. Leeds University Press, 1996: 79-83Google Scholar, 8Stanley M.A. Antivir. Res. 1994; 24: 1-15Crossref PubMed Scopus (33) Google Scholar, 9Hagensee M.E. Galloway D.A. Lacey C. Papillomavirus Reviews: Current Research on Papillomaviruses. Leeds University Press, 1996: 85-92Google Scholar). Sequences with inhibitory function have been identified on HPV-1 (10Tan W. Schwartz S. J. Virol. 1995; 69: 2932-2945Crossref PubMed Google Scholar), HPV-16 (11Kennedy I.M. Haddow J.K. Clements J.B. J. Virol. 1991; 65: 2093-2097Crossref PubMed Google Scholar), and BPV-1 (12Furth P.A. Baker C.C. J. Virol. 1991; 65: 5806-5812Crossref PubMed Google Scholar) late mRNAs. Inhibitory RNA elements present in the HPV-16 L1 and L2 coding regions (13Tan W. Felber B.K. Zolotukhin A.S. Pavlakis G.N. Schwartz S. J. Virol. 1995; 69: 5607-5620Crossref PubMed Google Scholar, 14Sokolowski M. Tan W. Jellne M. Schwartz S. J. Virol. 1998; 72: 1504-1515Crossref PubMed Google Scholar, 15Schwartz S. Semin. Virol. 1997; 8: 1-11Crossref Google Scholar) reduce the levels of late mRNAs and proteins, and a negative element in the late 3′-untranslated region (11Kennedy I.M. Haddow J.K. Clements J.B. J. Virol. 1991; 65: 2093-2097Crossref PubMed Google Scholar, 13Tan W. Felber B.K. Zolotukhin A.S. Pavlakis G.N. Schwartz S. J. Virol. 1995; 69: 5607-5620Crossref PubMed Google Scholar, 16Dietrich-Goetz W. Kennedy I.M. Levins B. Stanley M.A. Clements J.B. Proc. Natl. Acad. Sci. U. S. A. 1997; 94: 163-168Crossref PubMed Scopus (39) Google Scholar, 19Furth P.A. Choe W.-T. Rex J.H. Byrne J.C. Baker C.C. Mol. Cell. Biol. 1995; 14: 5278-5289Crossref Scopus (128) Google Scholar) was seen to reduce RNA stability in vitro (11Kennedy I.M. Haddow J.K. Clements J.B. J. Virol. 1991; 65: 2093-2097Crossref PubMed Google Scholar). The inhibitory RNA sequences on the late papillomavirus mRNAs are probably important determinants of virus late gene expression levels, presumably as a result of interactions with cellular RNA binding factors (16Dietrich-Goetz W. Kennedy I.M. Levins B. Stanley M.A. Clements J.B. Proc. Natl. Acad. Sci. U. S. A. 1997; 94: 163-168Crossref PubMed Scopus (39) Google Scholar, 17Zhao C. Tan W. Sokolowski M. Schwartz S. J. Virol. 1996; 70: 3659-3667Crossref PubMed Google Scholar, 18Sokolowski M. Zhao C. Tan W. Schwartz S. Oncogene. 1997; 15: 2303-2319Crossref PubMed Scopus (51) Google Scholar, 19Furth P.A. Choe W.-T. Rex J.H. Byrne J.C. Baker C.C. Mol. Cell. Biol. 1995; 14: 5278-5289Crossref Scopus (128) Google Scholar). Nuclear proteins may affect splicing, stability, and export, whereas cytoplasmic proteins may affect the utilization of the mRNA by inhibiting translation, altering the subcytoplasmic localization or mRNA stability (20Dreyfuss G. Matunis M.J. Pinol-Roma S. Burd C.G. Annu. Rev. Biochem. 1993; 62: 289-321Crossref PubMed Scopus (1320) Google Scholar, 21Ross J. Micobiol. Rev. 1995; 59: 15-95Google Scholar). human papillomavirus heterogenous ribonucleoprotein K poly(rC)-binding-protein 1 poly(rC)-binding protein 2 glutathione S-transferase chloramphenicol acetyltransferase enzyme-linked immunosorbent assay. human papillomavirus heterogenous ribonucleoprotein K poly(rC)-binding-protein 1 poly(rC)-binding protein 2 glutathione S-transferase chloramphenicol acetyltransferase enzyme-linked immunosorbent assay. Expression of HPV-16 L2 from subgenomic expression plasmids is very inefficient and we were unable to detect L2 protein after transfection of eucaryotic expression plasmids designed to produce L2 in cells M. Tan W. Jellne M. Schwartz S. J. Virol. 1998; 72: 1504-1515Crossref PubMed Google Scholar). The levels of various cellular and viral genes that we have to we that the L2 coding region may sequences that L2 an to we that sequences in the end of the L2 coding region were responsible for the of the L2 whereas sequences in the 3′ end of L2 reduce protein levels approximately without substantially affecting mRNA levels after a gene M. Tan W. Jellne M. Schwartz S. J. Virol. 1998; 72: 1504-1515Crossref PubMed Google Scholar). we have identified cellular proteins that specifically with the 3′ end of the L2 coding region the inhibitory RNA proteins were hnRNP K and and of the L2 open reading in vitro was specifically inhibited by the of these proteins, that L2 production is regulated by binding of these factors to the L2 mRNA in the infected epithelial was by a HPV-16 L2 sequences from to in the HPV-16 genomic G. M. S. Virology. PubMed Scopus Google Scholar) and by into in two were into the L2 sequence in by as previously Tan W. Schwartz S. J. Virol. 1995; 69: PubMed Google Scholar). The were located at and to in the HPV-16 genomic G. M. S. Virology. PubMed Scopus Google Scholar). The was with and in sequences the RNA and the L2 were by the plasmids with and in of over and to to was and which in a the of HPV-16 was by an encoding from a H. J. Biochem. 1995; PubMed Scopus Google Scholar) to The was by from (13Tan W. Felber B.K. Zolotukhin A.S. Pavlakis G.N. Schwartz S. J. Virol. 1995; 69: 5607-5620Crossref PubMed Google Scholar) into was by into of HPV-16 L2 sequences with and was by into of the open reading from and Nuclear and cytoplasmic used in experiments were from cells to the by Nucleic Res. PubMed Scopus Google Scholar). PCBP-1, PCBP-2, hnRNP K, and were expressed from H. J. Biochem. 1995; PubMed Scopus Google Scholar, B. J. J. Biol. 1996; PubMed Scopus Google Scholar) and purified with the vitro were as previously C. Tan W. Sokolowski M. Schwartz S. J. Virol. 1996; 70: 3659-3667Crossref PubMed Google Scholar). The RNA are in 1 A. RNA shift UV cross-linking, and of UV proteins were as previously C. Tan W. Sokolowski M. Schwartz S. J. Virol. 1996; 70: 3659-3667Crossref PubMed Google M. Zhao C. Tan W. Schwartz S. Oncogene. 1997; 15: 2303-2319Crossref PubMed Scopus (51) Google Scholar). of proteins were used in UV assay. vitro translation of mRNA was in a or in the to in the or of cells were infected with virus T.R. B. Proc. Natl. Acad. Sci. U. S. A. PubMed Scopus Google Scholar), RNA and with of or in the or of as previously (13Tan W. Felber B.K. Zolotukhin A.S. Pavlakis G.N. Schwartz S. J. Virol. 1995; 69: 5607-5620Crossref PubMed Google Scholar). The of used is in the The of DNA in transfection was to of by transfection was at Production of protein was by a to the was as previously (13Tan W. Felber B.K. Zolotukhin A.S. Pavlakis G.N. Schwartz S. J. Virol. 1995; 69: 5607-5620Crossref PubMed Google Scholar, 18Sokolowski M. Zhao C. Tan W. Schwartz S. Oncogene. 1997; 15: 2303-2319Crossref PubMed Scopus (51) Google Scholar). The J. Virol. 1997; PubMed Google Scholar) was by and was used at a of in and in The HPV-16 L2 J. J. J. Virol. 1991; 65: PubMed Google Scholar) by J. was used at a as (13Tan W. Felber B.K. Zolotukhin A.S. Pavlakis G.N. Schwartz S. J. Virol. 1995; 69: 5607-5620Crossref PubMed Google Scholar, 18Sokolowski M. Zhao C. Tan W. Schwartz S. Oncogene. 1997; 15: 2303-2319Crossref PubMed Scopus (51) Google Scholar, J. Schwartz S. Virology. 1995; PubMed Scopus Google Scholar). Expression of HPV-16 late genes L1 and L2 is restricted to terminally differentiated cells in squamous epithelium (1Howley P.M. Fields B.N. Knipe D.M. Howley P.M. Fields Virology. 3rd Ed. 2. Lippincott-Raven, Philadelphia1996: 2045-2076Google Scholar, 5Chow L.T. Broker T.R. Intervirology. 1994; 37: 150-158Crossref PubMed Scopus (119) Google Scholar, 6Laimins L.A. Infect. Agents Dis. 1993; 2: 74-86PubMed Google Scholar, 7Meyers C. Laimins L.A. Lacey C. Papillomavirus Reviews: Current Research on Papillomaviruses. Leeds University Press, 1996: 79-83Google Scholar, 8Stanley M.A. Antivir. Res. 1994; 24: 1-15Crossref PubMed Scopus (33) Google Scholar, 9Hagensee M.E. Galloway D.A. Lacey C. Papillomavirus Reviews: Current Research on Papillomaviruses. Leeds University Press, 1996: 85-92Google Scholar). We have previously that the HPV-16 L2 mRNA coding region sequences that expression of L2 in differentiated cells M. Tan W. Jellne M. Schwartz S. J. Virol. 1998; 72: 1504-1515Crossref PubMed Google Scholar). The 3′ end of L2 sequences that protein production without substantially affecting mRNA levels M. Tan W. Jellne M. Schwartz S. J. Virol. 1998; 72: 1504-1515Crossref PubMed Google Scholar). cellular factors with the 3′ end of the L2 mRNA, a of RNA gel shift and UV assays were and the are in The L2 RNA are in 1 A. can be seen in L2 RNA with from a was inhibited by an of L2 RNA by was cytoplasmic presumably the cytoplasmic L2 proteins and the the interaction of cellular proteins with the L2 inhibitory RNA was of interest to UV assays in to the proteins were binding to the L2 three cellular proteins and with of and respectively, were to with sequence they to the sense L2 RNA strand and to the as in 1 protein A and were primarily in the protein was primarily in the cytoplasmic 1 UV in the of of in more of protein A 1 Analysis of L2 1 that proteins A and with the 3′ end of the L2 RNA protein with the end of the RNA A of the gel was to detect protein proteins and specifically with L2 they of and was was they may play in the regulation of HPV-16 late gene we that proteins bound to L2 RNA specifically was of interest to in of their We to the proteins interacting with the L2 RNA for experiments were with and with by the of L2 RNA and UV The in A the binding of protein for poly(rC) and the binding of protein for of for of protein A that for poly(rC) and that binding to L2 RNA was by and 2 proteins have been as binding for (20Dreyfuss G. Matunis M.J. Pinol-Roma S. Burd C.G. Annu. Rev. Biochem. 1993; 62: 289-321Crossref PubMed Scopus (1320) Google Scholar, 21Ross J. Micobiol. Rev. 1995; 59: 15-95Google Scholar), was of interest to the of proteins and for various with different were 1 with a of efficiently for proteins A and 2 whereas 2 with a of to with the L2 RNA that proteins A and have for the L2 proteins, UV experiments were in the of of or and or 8 and the are in 2 can be the binding of proteins A and is with of 2 in the of of binding is to in both 2 an in binding with of a of binding in the of 2 and A protein of was binding to the L2 RNA in the of and 8 protein was to specifically to to the L2 RNA may be of interest to have for the L2 of the we the of proteins A and as hnRNP K and PCBP-2, hnRNP K is a protein with function and for poly(rC) and (20Dreyfuss G. Matunis M.J. Pinol-Roma S. Burd C.G. Annu. Rev. Biochem. 1993; 62: 289-321Crossref PubMed Scopus (1320) Google Scholar), PCBP-2 is a cytoplasmic protein that poly(rC) and H. J. Biochem. 1995; PubMed Scopus Google Scholar). We a to hnRNP K (20Dreyfuss G. Matunis M.J. Pinol-Roma S. Burd C.G. Annu. Rev. Biochem. 1993; 62: 289-321Crossref PubMed Scopus (1320) Google Scholar) and a PCBP-2 J. Virol. 1997; PubMed Google Scholar) which were used in a of RNA gel shift assays and can be seen in L2 mRNA UV in the of and cytoplasmic and with a to PCBP-2 J. Virol. 1997; PubMed Google Scholar) the of a at the of UV proteins is from result that is PCBP-2 interacting with the L2 RNA that to a in the cytoplasmic than in the that is in the A for the of two proteins with the may be that one is an of PCBP-2 or is PCBP-1, a they both have and the PCBP-2 with 1997; Google Scholar). result was as two proteins were detected in the cytoplasmic of cells in a the The of two in the UV be as the interaction of two proteins with the L2 the protein A interacting with the L2 RNA be hnRNP K, was with hnRNP K (20Dreyfuss G. Matunis M.J. Pinol-Roma S. Burd C.G. Annu. Rev. Biochem. 1993; 62: 289-321Crossref PubMed Scopus (1320) Google Scholar) to of the in RNA shift assay. was used we were unable to hnRNP K with can be seen in and the of L2 RNA with an to and the hnRNP K (20Dreyfuss G. Matunis M.J. Pinol-Roma S. Burd C.G. Annu. Rev. Biochem. 1993; 62: 289-321Crossref PubMed Scopus (1320) Google Scholar) is with of is to HPV-16 L1 protein on and the of the hnRNP K Therefore, the from is that the hnRNP K interactions hnRNP K and the L2 the by and gel shift proteins of hnRNP K, PCBP-1, and PCBP-2 were in a expression and were partially was to the of and PCBP-2 and the that two UV proteins were with the PCBP-2 that we to with L2 The in 2 and the interaction of both and PCBP-2 to L2 sense RNA and that these proteins have very binding to the L2 RNA The binding to the L2 RNA presumably the proteins are present in than in the and the interaction of K to L2 is that hnRNP K a L2 sense mRNA than to the L2 mRNA. UV to L2 RNA for the cytoplasmic proteins A and PCBP-1, PCBP-2, and hnRNP K primarily with the 3′ end of the L2 RNA sequence and RNA gel shift assays that RNA efficiently with the for binding of the proteins, whereas RNA the of the these that both PCBP-2 and hnRNP K in a sequence with the L2 mRNA. We these to the binding of to the HPV-16 L2 mRNA. We have previously that the of the HPV-16 L1 or L2 coding regions of the gene in of production (13Tan W. Felber B.K. Zolotukhin A.S. Pavlakis G.N. Schwartz S. J. Virol. 1995; 69: 5607-5620Crossref PubMed Google Scholar, 14Sokolowski M. Tan W. Jellne M. Schwartz S. J. Virol. 1998; 72: 1504-1515Crossref PubMed Google Scholar, 15Schwartz S. Semin. Virol. 1997; 8: 1-11Crossref Google Scholar). The L1 and L2 coding sequences from production M. Tan W. Jellne M. Schwartz S. J. Virol. 1998; 72: 1504-1515Crossref PubMed Google Scholar). The negative element to the 3′ end of the HPV-16 L2 coding sequence inhibited gene expression M. Tan W. Jellne M. Schwartz S. J. Virol. 1998; 72: 1504-1515Crossref PubMed Google Scholar), the negative element in the 3′ end of HPV-16 L1 inhibited gene expression (13Tan W. Felber B.K. Zolotukhin A.S. Pavlakis G.N. Schwartz S. J. Virol. 1995; 69: 5607-5620Crossref PubMed Google Scholar) and the region from gene expression than in that the proteins detected with the HPV-16 L2 RNA used here may to HPV-16 L1 they may with with the HPV-1 L2 sequence that inhibitory the of the HPV-16 L1 open reading and the of the HPV-1 L2 open reading were used as in an RNA gel shift with the HPV-16 L2 RNA and The that HPV-16 L1 RNA efficiently with the HPV-16 L2 that may affect HPV-16 L1 production the HPV-1 L2 RNA efficiently with the HPV-16 L2 RNA The with were and are in H. the inhibitory of the various HPV sequences in cells with their for the we that PCBP-1, PCBP-2, and hnRNP K were binding specifically to the L2 mRNA, was to the role of the A of these proteins been to in vitro translation of the RNA A. M. M. Cell. 1997; PubMed Scopus Google Scholar). Therefore, we the of PCBP-1, PCBP-2, and hnRNP K on the translation of the L2 mRNA and on the mRNA, used here as an The was in two different the and the with L2 and three proteins are in cells (20Dreyfuss G. Matunis M.J. Pinol-Roma S. Burd C.G. Annu. Rev. Biochem. 1993; 62: 289-321Crossref PubMed Scopus (1320) Google Scholar, 1997; Google Scholar), we a of the three proteins in vitro translation of HPV-16 in a of PCBP-1, PCBP-2, and hnRNP K translation of the L2 mRNA. A of the proteins and an of is on the mRNA the are to the in and the from the to of the protein levels by that of the three proteins the translation of L2 mRNA and respectively, in the two translation The of L2 in the or of PCBP-1, PCBP-2, and hnRNP K in three experiments was The protein levels were with and in The protein as the PCBP-1, PCBP-2, and hnRNP K are present or A and L2 mRNA and mRNA. Interestingly, protein inhibited L2 translation to a as the of the three proteins and was and The of the L2 sequence of the as in inhibited production in the of that the L2 sequence as a for the inhibitory proteins, in a translation of from mRNAs was by in vitro translation of HPV-16 L2 and mRNA in the or of 1 of 1 of PCBP-2 or a of PCBP-1, PCBP-2, and hnRNP K proteins The L2 protein levels were in a and are The protein levels are by the in vitro translation of HPV-16 L2 and mRNA in the or of 1 or of hnRNP K protein 2 and the proteins production of HPV-16 L2 in cells, we used the virus expression T.R. B. Proc. Natl. Acad. Sci. U. S. A. PubMed Scopus Google Scholar), which production of levels of HPV-16 L2 the of inhibitory sequences M. Tan W. Jellne M. Schwartz S. J. Virol. 1998; 72: 1504-1515Crossref PubMed Google Scholar), presumably a result of the expression levels in The HPV-16 L2 expression and the were into virus T.R. B. Proc. Natl. Acad. Sci. U. S. A. PubMed Scopus Google cells in the or of the expression transfection was at Production of L2 was by the L2 levels were by and the levels were in a The that production of HPV-16 L2 in human epithelial cells the levels of from the are by of the L2 is in C. of and with various of the the coding affect production of HPV-16 L2 We that L2 production in human transfection of cells with a that L2 sequences of in the of of in a in levels that the of the L2 sequence on the mRNA expression of a mRNA. The levels from the were by a we and with various of the the that coding with affect production from or from of in cells specifically inhibited protein production from mRNAs HPV-16 L2 three proteins were to specifically with the L2 sense RNA A protein and two poly(rC)-binding proteins were identified as PCBP-2 and hnRNP of the protein was a of proteins with have been J. Micobiol. Rev. 1995; 59: 15-95Google Scholar). the expressed protein which is present at levels in cells S. C. A. H. J. 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Biochem. 1995; PubMed Scopus Google Scholar, 1997; Google Scholar), the L2 sequence a of in and three in the L2 sequence or more the and hnRNP K proteins a for the L2 mRNA. is by the that these proteins are interacting with the strand of the L2 the of L2 at is than in the mRNA which may be one for the of the and hnRNP K for the L2 the L2 sequence may binding for and hnRNP K proteins, to RNA proteins and mRNA is RNA binding present in the is that the interaction hnRNP K and the L2 inhibitory element is by the of three of a the as as two H. J. Biochem. 1996; PubMed Scopus Google Scholar). The PCBP-2 and to that with L2, and in vitro experiments The and three H. J. Biochem. 1996; PubMed Scopus Google Scholar). Therefore, is that the of both and and hnRNP K are responsible for the interaction with the L2 mRNA. is by the that have been to poly(rC) M.J. G. Mol. Cell. Biol. PubMed Scopus Google Scholar) and that poly(rC) with L2 RNA for binding to these a role for these proteins, one their binding with the of the which is to the of epithelium L.T. Broker T.R. Intervirology. 1994; 37: 150-158Crossref PubMed Scopus (119) Google Scholar, 6Laimins L.A. Infect. Agents Dis. 1993; 2: 74-86PubMed Google Scholar, 7Meyers C. Laimins L.A. Lacey C. Papillomavirus Reviews: Current Research on Papillomaviruses. Leeds University Press, 1996: 79-83Google Scholar, 8Stanley M.A. Antivir. Res. 1994; 24: 1-15Crossref PubMed Scopus (33) Google Scholar, 9Hagensee M.E. Galloway D.A. Lacey C. Papillomavirus Reviews: Current Research on Papillomaviruses. Leeds University Press, 1996: 85-92Google Scholar). The of hnRNP K and and to translation of the L2 mRNA to a of the levels of L2 protein in the layers of the epithelium of the is that HPV factors to viral capsid production the of present in the epithelium. a L2 protein is present from the to the the mRNA can be in the interaction of hnRNP K and and with L2 mRNA with in the epithelium as L2 mRNA is to epithelium is that the the of cytoplasmic mRNAs may be to the of of the been previously that hnRNP K and the in vitro translation of mRNA A. M. M. Cell. 1997; PubMed Scopus Google Scholar). The levels of mRNA are in cells, protein is the of the is The of translation is seen to be by a element in the 3′-untranslated region and the binding of hnRNP K and to The used by these proteins the of on mRNA and of and translation by binding to elements A. M. M. Cell. 1997; PubMed Scopus Google Scholar). The that the inhibitory L2 sequence is located of the open reading that translation initiation is as in mRNA. is that hnRNP K and and translation of cellular and virus mRNAs in to in different We H. G. J. and for and A. and for with for with for and G. for reading of the