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Differences in Transcriptional Activity of Human Papillomavirus Type 6 Molecular Variants in Recurrent Respiratory Papillomatosis.

Measso do Bonfim C, Simão Sobrinho J, Lacerda Nogueira R, Salgado Kupper D, Cardoso Pereira Valera F, Lacerda Nogueira M, Villa LL, Rahal P, Sichero L - PLoS ONE (2015)

Bottom Line: Furthermore, our results support a crucial role for ELF1 on transcriptional downregulation.We identified TFs implicated in the regulation of HPV-6 early gene expression.Many of these factors are mutated in cancer or are putative cancer biomarkers, and must be further studied.

View Article: PubMed Central - PubMed

Affiliation: Laboratory of Genomic Studies, Universidade do Estado de São Paulo, UNESP, São José do Rio Preto, SP, Brazil.

ABSTRACT
A significant proportion of recurrent respiratory papillomatosis (RRP) is caused by human papillomavirus type 6 (HPV-6). The long control region (LCR) contains cis-elements for regulation of transcription. Our aim was to characterize LCR HPV-6 variants in RRP cases, compare promoter activity of these isolates and search for cellular transcription factors (TFs) that could explain the differences observed. The complete LCR from 13 RRP was analyzed. Transcriptional activity of 5 variants was compared using luciferase assays. Differences in putative TFs binding sites among variants were revealed using the TRANSFAC database. Chromatin immunoprecipation (CHIP) and luciferase assays were used to evaluate TF binding and impact upon transcription, respectively. Juvenile-onset RRP cases harbored exclusively HPV-6vc related variants, whereas among adult-onset cases HPV-6a variants were more prevalent. The HPV-6vc reference was more transcriptionally active than the HPV-6a reference. Active FOXA1, ELF1 and GATA1 binding sites overlap variable nucleotide positions among isolates and influenced LCR activity. Furthermore, our results support a crucial role for ELF1 on transcriptional downregulation. We identified TFs implicated in the regulation of HPV-6 early gene expression. Many of these factors are mutated in cancer or are putative cancer biomarkers, and must be further studied.

No MeSH data available.


Related in: MedlinePlus

Molecular variants of HPV-6 differ in early promoter activity.(A) Transcriptional activity of human papillomavirus type (HPV-6) molecular variants isolated from recurrent respiratory papillomatosis (RRP) cases. Data are presented as mean ± SD relative values from 3 independent experiments. Transcriptional activity was normalized to that of HPV-6a-ref which was arbitrarily defined as the reference and set to value 1. Kruskal-Wallis and Tukey’s tests were used to compare LCR activity among the different HPV-6 molecular variants. Asterisks indicate isolates that showed statistically significant different transcriptional activities compared to the corresponding references (HPV-6a-ref or HPV-6vc-ref). (P<0.001). (B) Putative cellular transcription factors binding sites within the long control region (LCR) that differ among the different molecular variants of human papillomavirus (HPV) type 6 detected.
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pone.0132325.g001: Molecular variants of HPV-6 differ in early promoter activity.(A) Transcriptional activity of human papillomavirus type (HPV-6) molecular variants isolated from recurrent respiratory papillomatosis (RRP) cases. Data are presented as mean ± SD relative values from 3 independent experiments. Transcriptional activity was normalized to that of HPV-6a-ref which was arbitrarily defined as the reference and set to value 1. Kruskal-Wallis and Tukey’s tests were used to compare LCR activity among the different HPV-6 molecular variants. Asterisks indicate isolates that showed statistically significant different transcriptional activities compared to the corresponding references (HPV-6a-ref or HPV-6vc-ref). (P<0.001). (B) Putative cellular transcription factors binding sites within the long control region (LCR) that differ among the different molecular variants of human papillomavirus (HPV) type 6 detected.

Mentions: Luciferase assays were used to access the impact of LCR nucleotide sequence heterogeneity on early viral transcription. Unfortunately, we were unable to construct a recombinant plasmid containing the HPV-6a-var2 LCR. We observed an 11.5 fold enhanced promoter activity for HPV-6vc-ref variant as compared to HPV-6a-ref. A transition at nucleotide position 16 detected solely in HPV-6a-var1 led to an increase in transcriptional activity similar to that of the HPV-6vc-ref, whereas the transversion at position 7630 inherent of the HPV-6vc-var1 abolished the increased activity observed for HPV-6-vc-ref. HPV-6vc-var2 and -6vc-var3 showed promoter activities similar to HPV-6vc-ref (Fig 1A)


Differences in Transcriptional Activity of Human Papillomavirus Type 6 Molecular Variants in Recurrent Respiratory Papillomatosis.

Measso do Bonfim C, Simão Sobrinho J, Lacerda Nogueira R, Salgado Kupper D, Cardoso Pereira Valera F, Lacerda Nogueira M, Villa LL, Rahal P, Sichero L - PLoS ONE (2015)

Molecular variants of HPV-6 differ in early promoter activity.(A) Transcriptional activity of human papillomavirus type (HPV-6) molecular variants isolated from recurrent respiratory papillomatosis (RRP) cases. Data are presented as mean ± SD relative values from 3 independent experiments. Transcriptional activity was normalized to that of HPV-6a-ref which was arbitrarily defined as the reference and set to value 1. Kruskal-Wallis and Tukey’s tests were used to compare LCR activity among the different HPV-6 molecular variants. Asterisks indicate isolates that showed statistically significant different transcriptional activities compared to the corresponding references (HPV-6a-ref or HPV-6vc-ref). (P<0.001). (B) Putative cellular transcription factors binding sites within the long control region (LCR) that differ among the different molecular variants of human papillomavirus (HPV) type 6 detected.
© Copyright Policy
Related In: Results  -  Collection

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Show All Figures
getmorefigures.php?uid=PMC4494706&req=5

pone.0132325.g001: Molecular variants of HPV-6 differ in early promoter activity.(A) Transcriptional activity of human papillomavirus type (HPV-6) molecular variants isolated from recurrent respiratory papillomatosis (RRP) cases. Data are presented as mean ± SD relative values from 3 independent experiments. Transcriptional activity was normalized to that of HPV-6a-ref which was arbitrarily defined as the reference and set to value 1. Kruskal-Wallis and Tukey’s tests were used to compare LCR activity among the different HPV-6 molecular variants. Asterisks indicate isolates that showed statistically significant different transcriptional activities compared to the corresponding references (HPV-6a-ref or HPV-6vc-ref). (P<0.001). (B) Putative cellular transcription factors binding sites within the long control region (LCR) that differ among the different molecular variants of human papillomavirus (HPV) type 6 detected.
Mentions: Luciferase assays were used to access the impact of LCR nucleotide sequence heterogeneity on early viral transcription. Unfortunately, we were unable to construct a recombinant plasmid containing the HPV-6a-var2 LCR. We observed an 11.5 fold enhanced promoter activity for HPV-6vc-ref variant as compared to HPV-6a-ref. A transition at nucleotide position 16 detected solely in HPV-6a-var1 led to an increase in transcriptional activity similar to that of the HPV-6vc-ref, whereas the transversion at position 7630 inherent of the HPV-6vc-var1 abolished the increased activity observed for HPV-6-vc-ref. HPV-6vc-var2 and -6vc-var3 showed promoter activities similar to HPV-6vc-ref (Fig 1A)

Bottom Line: Furthermore, our results support a crucial role for ELF1 on transcriptional downregulation.We identified TFs implicated in the regulation of HPV-6 early gene expression.Many of these factors are mutated in cancer or are putative cancer biomarkers, and must be further studied.

View Article: PubMed Central - PubMed

Affiliation: Laboratory of Genomic Studies, Universidade do Estado de São Paulo, UNESP, São José do Rio Preto, SP, Brazil.

ABSTRACT
A significant proportion of recurrent respiratory papillomatosis (RRP) is caused by human papillomavirus type 6 (HPV-6). The long control region (LCR) contains cis-elements for regulation of transcription. Our aim was to characterize LCR HPV-6 variants in RRP cases, compare promoter activity of these isolates and search for cellular transcription factors (TFs) that could explain the differences observed. The complete LCR from 13 RRP was analyzed. Transcriptional activity of 5 variants was compared using luciferase assays. Differences in putative TFs binding sites among variants were revealed using the TRANSFAC database. Chromatin immunoprecipation (CHIP) and luciferase assays were used to evaluate TF binding and impact upon transcription, respectively. Juvenile-onset RRP cases harbored exclusively HPV-6vc related variants, whereas among adult-onset cases HPV-6a variants were more prevalent. The HPV-6vc reference was more transcriptionally active than the HPV-6a reference. Active FOXA1, ELF1 and GATA1 binding sites overlap variable nucleotide positions among isolates and influenced LCR activity. Furthermore, our results support a crucial role for ELF1 on transcriptional downregulation. We identified TFs implicated in the regulation of HPV-6 early gene expression. Many of these factors are mutated in cancer or are putative cancer biomarkers, and must be further studied.

No MeSH data available.


Related in: MedlinePlus