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A Pater

Publications and source records attributed to A Pater.

At least 73 records · Page 4Linked to original sources
PubMed1990

Activity and enhancer binding factors for JC virus regulatory elements in differentiating embryonal carcinoma cells.

We have studied cell-type-specific expression by JC virus (JCV) DNA regulatory sequences using embryonal carcinoma (EC) cells as a model system. In transient transfection assays, JCV enhancer demonstrated activity in retinoic acid-differentiated neuronal type cells but not in undifferentiated or DMSO-differentiated muscle type cells. To correlate in vivo activity with the binding of transcription factors, we performed DNasel footprinting experiments. Retinoic acid-treated EC cell extracts provided three completely protected regions, each containing sequences with homology to nuclear factor 1 (NF1) binding motifs and the partially protected TATA box. Oligonucleotide competition studies suggest that all three NF1 binding motifs are bound by the same factors but with different affinities and that there are cooperative interactions between NF1 proteins binding to adjacent regions. No protected region other than the partially protected TATA box was detected in undifferentiated and DMSO-differentiated EC cells in which JC regulatory sequences were not expressed.

Animals↗
PubMed1989

Trans-regulation and differential cell specificity of human papillomavirus types 16, 18, and 11 cis-acting elements.

The noncoding region (ncr) of human papillomavirus (HPV) types 16, 18, and 11 contains promoter and/or enhancer function. We have localized the sequence containing the constitutive enhancers of HPV types 16, 18, and 11 to 315, 230, and 213 bp fragments, respectively, for comparative studies. The region of homology shared between the enhancers of the three viruses is limited to the sequence ATTTTTGGCTT, which is also present in the ncr of HPV 6b and 33. We have also examined the enhancer activity of the HPV ncrs in three human cervical carcinoma cell lines, one noncervical human carcinoma cell line, and one monkey kidney established cell line. We observed cell-specific differences in the constitutive expression of the enhancers in the various cell lines. The conditional enhancer activity of the ncr of the viruses is increased in trans by the E2 gene product of HPV 16. Transactivation by E2 is mediated through the E2 binding motif on HPV enhancer plasmids with a heterologous but not with a homologous promoter. Our preliminary studies also indicate a repressor function for the E7 gene of HPV 16.

Base Sequence↗
PubMed1988

Glucocorticoid-dependent oncogenic transformation by type 16 but not type 11 human papilloma virus DNA.

Squamous cell carcinoma of the uterine cervix is one of the most common cancers among women. Correlation between human papilloma virus (HPV) infection of the uterine cervix and the development of cervical neoplasia has been established. More recent studies have shown the presence and expression of integrated HPV types 16 and 18 DNA sequences in 70-80% of cervical tumours and tumour cell lines. It has been suggested that, in addition to HPVs, other agents such as hormones and tobacco products act as cofactors in cervical neoplasia (for review see ref. 15). The presence and expression of a glucocorticoid-responsive element in HPV-16 has been reported. Here we provide evidence for the oncogenic transformation of primary cells with a combination of HPV-16 DNA, but not HPV-11 DNA, and the activated form of the human Ha-ras oncogene only in the presence of the glucocorticoid hormone dexamethasone.

Animals↗
PubMed1988

Isolation and characterization of a variant of human papillomavirus type 11 from a nasal inverting (Schneiderian) papilloma.

We have previously reported the presence of a variant of human papillomavirus (HPV) type 11 in a nasal inverting papilloma [Respler et al., 1987]. In the present study, we have cloned molecularly the DNA of this variant at its unique restriction enzyme Bam HI site into lambda BF101 phage. Restriction enzyme mapping and DNA sequencing revealed that the genome of this virus contained an extra 531 base pair (bp) which was the repeat of most of the noncoding region (ncr) of HPV 11. Insertion of transcriptional control elements, including the repeated sequence, in front of the chloramphenicol acetyltransferase (CAT) gene resulted in a 5- to 30-fold increase in expression in transfected cells, as compared to the constructs containing a single ncr of HPV 11. This increased expression was due to enhanced levels of CAT RNA the synthesis of which is initiated by the viral promoter element.

Acetyltransferases↗
PubMed1988

Expression of human papillomavirus types 16 and 18 DNA sequences in cervical carcinoma cell lines.

A total of six cervical carcinoma cell lines, of which two contained human papillomavirus (HPV) type 16 and four contained HPV type 18 DNA, were examined for viral RNA expression by spot-blot hybridization. All six cell lines contained HPV-specific cytoplasmic poly(A)-containing RNA. The same RNA species were detected in both cytoplasmic and polysomal fractions, indicating nonselective translation of these messages into protein products. Primer extension analysis of RNA from the cell lines revealed the presence of three major start sites at the 5' end of the E6 gene for RNA from HPV 16-containing cell lines and four major start sites at the 5' end of the E6 gene for RNA from HPV 18-containing cell lines. One cell line, ME 180, had a distinct pattern with only one minor HPV 18 start site. Northern-blot hybridization using the E6-E7 region of HPV 16 and 18 DNAs as probes revealed the presence of E6-E7 transcripts in all the cell lines except ME 180. Southern-blot analysis revealed that while sequences hybridizing to the E6-E7 coding region were present, the 5' end region containing the enhancer-promoter region of viral DNA is deleted in ME 180. Subsequent Northern-blot hybridization using the E1 region of HPV 18 DNA as probe revealed that the viral RNA in ME 180 is transcribed from this region.

Blotting, Northern↗
PubMed1988

Expression of the control elements of BK and SV40 viruses in human cells exhibiting different transformed phenotypes.

Transformation of primary human embryonic kidney (HEK) cells as selected by either focus assay or growth in soft agar after their transfection with BK virus (BKV) DNA alone or BKV DNA plus the activated form of human Ha-ras oncogene has been previously reported (A. Pater and M. M. Pater, J. Virol. 58, 680-683 (1986]. In order to examine the expression of the regulatory elements of papovaviruses in each of the transformed phenotypes, chloramphenical acetyltransferase (CAT) plasmids under the control of BK or SV40 early promotor were used in transient assays. The expression of CAT, as driven by either SV40 or BK early promoters, was approximately 100-fold higher in HEK cells transformed by BKV DNA plus Ha-ras oncogene than in cells transformed only by BKV DNA. The higher CAT expression was not due to high levels of plasmid replication in these cells. Time course studies revealed that the higher CAT activity could be explained largely by greater plasmid uptake and stability in BK plus ras-transformed cells.

BK Virus↗
PubMed1988

Functional role of BK virus tumor antigens in transformation.

We have examined the role of the human papovavirus BK virus (BKV) tumor (T) antigen(s) in the maintenance of transformation and have identified the domain of T antigen essential for transformation. BKV-transformed BHK 21 and NIH 3T3 cells expressing antisense T-antigen RNA lose their ability to grow in soft agar, indicating the need for the continued expression of T antigen for the maintenance of the transformed phenotype. Experiments using translation termination linker insertion and deletion mutagenesis of BKV T antigen demonstrate that amino acids 356 to 384 are essential for transformation. Although BKV T antigen shares 100, 95, and 82% amino acid homology with that of simian virus 40 (SV40) for the nuclear localization signal, p53-binding domain, and DNA-binding domain, respectively, the transformation domains of BKV and SV40 T antigens share only 54% homology. Also, BKV T antigen lacks a substantial portion of the ATPase domain of SV40, and our results indicate the dispensability of the remaining portion for transformation by this protein. We suggest that the differences in the amino acids in the identified transformation domains together with the differences in the ATPase domains may account for the differences in the transformation potentials of the two proteins.

Animals↗
PubMed1986

Human papillomavirus types 16 and 18 sequences in early cervical neoplasia.

A total of 100 colposcopic biopsies from patients with abnormal Papanicolau's tests were surveyed for the presence of human papillomavirus (HPV) types 16 and 18 sequences by spot-blot hybridization. HPV 16 and 18 DNA sequences were detected in 58% of the biopsies. None of the cervical intraepithelial neoplasia grade I (CIN I) contained HPV 16 while 50% of the CIN III lesions (carcinoma in situ, CIS) contained HPV 16. HPV 18-related sequences were equally represented in CIN I, II, and III. Southern-blot hybridization of total undigested cellular DNA revealed the presence of HPV DNA sequences only in an episomal form. While the restriction enzyme patterns in HPV 16-positive samples were mostly identical to the originally cloned sequence, the restriction enzyme pattern for HPV 18-positive samples were different from that of HPV 18 but identical to each other. Furthermore, this DNA hybridized more strongly to HPV 18 under nonstringent conditions, suggesting a new type.

Colposcopy↗
PubMed1986

Transformation of primary human embryonic kidney cells to anchorage independence by a combination of BK virus DNA and the Harvey-ras oncogene.

Primary human embryonic kidney (HEK) cells were transformed by a focus assay with BK virus (BKV) DNA molecularly cloned at its unique EcoRI site. Both viral DNA sequences and viral tumor antigens were present and expressed in all the foci that we examined. However, cells isolated from foci were incapable of growth in soft agar. We then examined the transformation of HEK cells after their transfection with a combination of BKV DNA and either the normal or the activated form of the human Ha-ras oncogene (EJ c-Ha-ras-1). Only the cells transfected with a combination of BKV DNA and the activated form of Ha-ras were capable of growth in soft agar. Both BKV and Ha-ras DNAs were present in the transformed colonies. BKV tumor antigens and the Ha-ras p21 protein were also expressed.

Antigens, Viral, Tumor↗
PubMed1985

Human papillomavirus types 16 and 18 sequences in carcinoma cell lines of the cervix.

A total of eight human epithelial cell lines derived from the carcinoma of the cervix were examined for the presence of human papillomaviruses (HPVs) types 16 and 18 DNA sequences. Six out of eight cell lines contain sequences hybridizing to the DNA of these viruses. Two of the cell lines contain sequences hybridizing specifically to HPV 16. One of these two cell lines contains all of the HPV 16 sequences and the other cell line is missing fragments containing early regions E2 and E4 and some of the late regions. Four of the cell lines contain sequences hybridizing specifically to HPV 18. All these cell lines are missing fragments containing early regions E2, E4, and E5. Interestingly, all the cell lines contain sequences corresponding to early regions E1, E6, and E7.

Base Sequence↗
PubMed1984

Thymidine kinase of herpes virus as a vehicle for the isolation and characterization of unknown mammalian promoters and enhancers.

We have previously reported that the promoter of the thymidine kinase (TK) gene of herpes virus (HSV) can be replaced with the early promoter of SV40. In the present study we report the construction of a TK- plasmid (TK-pML-BglII) in which the TK promoter has been removed and a new BglII site has been regenerated for the insertion of exogenous promoters in front of this nonexpressed gene. We have tested the feasibility of using this plasmid for the isolation of unknown promoters by inserting DNA fragments containing the early and late promoters of human papovaviruses and have obtained activity. We have also inserted the fragments containing the 72-bp repeat enhancer sequences of SV40 and 107-bp repeat of the human BK virus into the intact TK plasmid (TK-pML) and observe increased frequency of transformation of mouse Ltk- cells to the TK+ phenotype. These results show that the TK system can be used as a vehicle for the isolation of unknown mammalian promoters and/or enhancers.

Animals↗
PubMed1983

Multiple origins of the complementary defective genomes of RF and origin proximal sequences of GS, two human papovavirus isolates.

It has previously been shown that the genome of RF virus, a variant of the human papovavirus, BK, consists of two DNA species, one (R1a) with a deletion corresponding to the early and the other (R2) with a deletion corresponding to the late region of BKV (A. Pater, M.M. Pater, and G. di Mayorca (1980). J. Virol. 36, 480-487; A. Pater, M. M. Pater, R. M. Dougherty, and G. di Mayorca (1981a). Virology 113, 86-94). In this report transfection experiments are used to show that these DNA species are individually defective for infection and that both DNA molecules are required simultaneously for the infection of human embryonic kidney (HEK) cells. DNA fragments containing the origin of replication in each of the DNA species are analyzed to show that R1a contains three and R2 contains two origins of replication. In addition, several changes in the repeat region proximal to the origin of replication are observed. The changes involve deletions and insertions. Examination of the deleted junctions most often reveals involvement of short stretches of repeated sequences (hot spots) in recombination. Another observed change is the insertion into R2 of a 63-bp sequence which contains no homology to either BK or SV40 DNA. This insertion is into the late-promoter region of this late-region coding DNA and appears to replace a poor "TATA" box in BK wild type with a better TATA box with the correct spacing from the "CAAT" box. A 304-bp fragment containing the origin of replication, early and late promoters, and the repeat units proximal to the origin of replication of GS, another variant of human BKV papovaviruses has also been sequenced. Several rearrangements, including deletions and insertions in the repeat region, are observed. Moreover, when homologous regions of this virus are compared to that of BKV, five base changes are detected, one of which is in the 23-bp origin region. This base change gives this 23-bp palindrome of GS a perfect two-fold rotational symmetry.

Cell Line↗
PubMed1983

Positive control of the herpes simplex virus thymidine kinase gene requires upstream DNA sequences.

We examined the ability of deleted versions of the herpes simplex virus type 1 thymidine kinase gene, present in biochemically transformed mouse cells, to be induced in trans to a higher level of expression by superinfecting herpes simplex virus immediate early gene products. The results demonstrate that sequences mapping between -200 and -80 and between -70 and -12 are required for induction. As these regions are largely coincident with the previously identified thymidine kinase gene promoter, the results suggest that herpes simplex virus immediate early gene products or their metabolic product activate thymidine kinase expression by acting at the promoter region to increase the rate of transcription.

Base Sequence↗
PubMed1982

BK virus-transformed inbred hamster brain cells: status of viral DNA in subclones.

We have recently reported that viral DNA sequences in inbred LSH hamster brain cells transformed by the GS variant of BK virus (LSH-BR-BK) are present predominantly in a free form (Beth et al., J. Virol. 40:276-284, 1981). In this report, we confirm that the presence of viral DNA sequences in these cells is not due to virus production, since viral capsid proteins were not detected by immunoprecipitation. Furthermore, we examined the status of viral DNA in 15 subclones of this cell line and detected free and integrated viral DNA sequences in only 5 of the subclones. The other 10 subclones contained exclusively integrated viral DNA sequences, as shown by the blot hybridization of high-molecular-weight cell DNA which was uncleaved or digested with HincII, for which there are no sites in viral DNA. The arrangement of viral DNA in these clones was further analyzed by cleavage of cellular DNA with HpaII and HindIII. Mitomycin (0.03 microgram/ml) treatment of subclones containing only integrated sequences resulted in the appearance of free viral DNA sequences in some of these cells. This result supports the postulation that free viral DNA in LSH-BR-BK cells is made up of excision products of observed tandemly repeated integrated sequences. In addition to the large T- and small t-antigens, LSH-BR-BK and all of its 15 subclones contained two antigen species which were larger than large T and one species which was smaller than small t. The number of tumor antigens in the LSH- BR-BK cell line and its subclones with a large copy number in a free form was not more than in the subclones with low copy number and integrated DNA. This suggests that free viral DNA is not a template for tumor antigen production in transformed cells.

Animals↗