Limits...
MYB elongation is regulated by the nucleic acid binding of NFκB p50 to the intronic stem-loop region.

Pereira LA, Hugo HJ, Malaterre J, Huiling X, Sonza S, Cures A, Purcell DF, Ramsland PA, Gerondakis S, Gonda TJ, Ramsay RG - PLoS ONE (2015)

Bottom Line: We identified a conserved lysine-rich motif within the Rel homology domain (RHD) of NFκBp50, mutation of which abrogated the interaction of NFκBp50 with the SLR polyU and impaired NFκBp50 mediated MYB elongation.Furthermore, we identify the DNA binding activity of NFκBp50 as a key component required for the SLR polyU mediated regulation of MYB.Collectively these results suggest that the MYB SLR polyU provides a platform for proteins to regulate MYB and reveals novel nucleic acid binding properties of NFκBp50 required for MYB regulation.

View Article: PubMed Central - PubMed

Affiliation: Differentiation and Transcription Laboratory, Peter MacCallum Cancer Centre, Locked Bag #1, Melbourne, Victoria, 8006, Australia; Sir Peter MacCallum Department of Oncology, The University of Melbourne, Parkville, Victoria, 3010, Australia.

ABSTRACT
MYB transcriptional elongation is regulated by an attenuator sequence within intron 1 that has been proposed to encode a RNA stem loop (SLR) followed by a polyU tract. We report that NFκBp50 can bind the SLR polyU RNA and promote MYB transcriptional elongation together with NFκBp65. We identified a conserved lysine-rich motif within the Rel homology domain (RHD) of NFκBp50, mutation of which abrogated the interaction of NFκBp50 with the SLR polyU and impaired NFκBp50 mediated MYB elongation. We observed that the TAR RNA-binding region of Tat is homologous to the NFκBp50 RHD lysine-rich motif, a finding consistent with HIV Tat acting as an effector of MYB transcriptional elongation in an SLR dependent manner. Furthermore, we identify the DNA binding activity of NFκBp50 as a key component required for the SLR polyU mediated regulation of MYB. Collectively these results suggest that the MYB SLR polyU provides a platform for proteins to regulate MYB and reveals novel nucleic acid binding properties of NFκBp50 required for MYB regulation.

No MeSH data available.


Related in: MedlinePlus

Model for the NFκBp50 and p65 regulation of MYB elongation through the intron 1 MYB SLR polyU region and upstream sequences.NFκBp50 binding at upstream sequences stimulates transcription from the multiple start sites. Transcripts are then paused/attenuated at the downstream MYB SLR polyU. In the absence of NFκBp65, NFκBp50 occupies the MYB SLR polyU region and MYB transcription is paused. In contrast the formation of a NFκBp50-p65 heterodimer on the MYB SLR polyU contributes to the stimulation of MYB transcription elongation by the NFκBp65-mediated recruitment of P-TEFb and the subsequent Ser2 phosphorylation of Pol II CTD (elongating form) by CDK9. This model is consistent with i) previous findings that NFκBp65 mediates transcriptional elongation through the direct recruitment of P-TEFb [50] and ii) our recent observations that ERα recruits P-TEFb to a region near the MYB SLR polyU and that this interaction is concordant with the accumulation of Ser2 CTD phosphorylated pol II bound to this region and the relief of MYB transcriptional attenuation [22]. This model also raises the possibility that the regulation of MYB may also involve the interaction of upstream bound NFκBp50/65 with the downstream intron 1 MYB SLR polyU. Recent data indicate that enhancer elements loop towards murine Myb intron 1 to bring the transcription apparatus to the vicinity of the pausing region and regulate Myb attenuation/elongation [19] and we have shown that the upstream regions of MYB lie in proximity to the MYB SLR polyU S5 Fig Furthermore, recent structure based analyses of HIV-1 LTR interactions suggest that pre-formed NFκBp50-DNA complexes can interact with downstream HIV TAR RNA [48].
© Copyright Policy
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC4390348&req=5

pone.0122919.g008: Model for the NFκBp50 and p65 regulation of MYB elongation through the intron 1 MYB SLR polyU region and upstream sequences.NFκBp50 binding at upstream sequences stimulates transcription from the multiple start sites. Transcripts are then paused/attenuated at the downstream MYB SLR polyU. In the absence of NFκBp65, NFκBp50 occupies the MYB SLR polyU region and MYB transcription is paused. In contrast the formation of a NFκBp50-p65 heterodimer on the MYB SLR polyU contributes to the stimulation of MYB transcription elongation by the NFκBp65-mediated recruitment of P-TEFb and the subsequent Ser2 phosphorylation of Pol II CTD (elongating form) by CDK9. This model is consistent with i) previous findings that NFκBp65 mediates transcriptional elongation through the direct recruitment of P-TEFb [50] and ii) our recent observations that ERα recruits P-TEFb to a region near the MYB SLR polyU and that this interaction is concordant with the accumulation of Ser2 CTD phosphorylated pol II bound to this region and the relief of MYB transcriptional attenuation [22]. This model also raises the possibility that the regulation of MYB may also involve the interaction of upstream bound NFκBp50/65 with the downstream intron 1 MYB SLR polyU. Recent data indicate that enhancer elements loop towards murine Myb intron 1 to bring the transcription apparatus to the vicinity of the pausing region and regulate Myb attenuation/elongation [19] and we have shown that the upstream regions of MYB lie in proximity to the MYB SLR polyU S5 Fig Furthermore, recent structure based analyses of HIV-1 LTR interactions suggest that pre-formed NFκBp50-DNA complexes can interact with downstream HIV TAR RNA [48].

Mentions: Previous studies have implicated NFκB family members in the regulation of transcriptional elongation through intron 1 of the murine MYB gene [23–25]. Notably, an NFκB enhancer element resides within intron 1 that is capable of binding NFκBp50, RelA, RelB and c-Rel in vitro [23–25]. In these studies, binding of NFκB complexes to this region was linked to the activation of endogenous MYB or MYB-CAT expression, suggesting that in case of the murine MYB gene transcriptional elongation through intron 1 is mediated by a DNA-dependent mechanism. Although the NFκB enhancer is potentially important to the regulation of the endogenous gene, it resides approximately 1.2 kbp downstream of the region investigated here and was excluded from the reporters examined in the current study. Nevertheless, this suggests that NFκBp50 may also contribute to the regulation of MYB via a region(s) upstream of the MYB SLR polyU. Consistent with this observation other reports have shown a role for a NFκB site found in the MYB promoter [49]. Collectively these observations suggest that NFκBp50 may regulate MYB through multiple regions/sites within the gene. In this case NFκBp50 bound at upstream sequences may stimulate transcription from the multiple start sites upstream of exon 1. Transcripts that are then stalled at the downstream MYB SLR polyU are released by the action of NFκBp50 at the MYB SLR polyU. In this way NFκBp50 may regulate MYB at at least two points within the gene using its nucleic acid binding activity (Fig 8).


MYB elongation is regulated by the nucleic acid binding of NFκB p50 to the intronic stem-loop region.

Pereira LA, Hugo HJ, Malaterre J, Huiling X, Sonza S, Cures A, Purcell DF, Ramsland PA, Gerondakis S, Gonda TJ, Ramsay RG - PLoS ONE (2015)

Model for the NFκBp50 and p65 regulation of MYB elongation through the intron 1 MYB SLR polyU region and upstream sequences.NFκBp50 binding at upstream sequences stimulates transcription from the multiple start sites. Transcripts are then paused/attenuated at the downstream MYB SLR polyU. In the absence of NFκBp65, NFκBp50 occupies the MYB SLR polyU region and MYB transcription is paused. In contrast the formation of a NFκBp50-p65 heterodimer on the MYB SLR polyU contributes to the stimulation of MYB transcription elongation by the NFκBp65-mediated recruitment of P-TEFb and the subsequent Ser2 phosphorylation of Pol II CTD (elongating form) by CDK9. This model is consistent with i) previous findings that NFκBp65 mediates transcriptional elongation through the direct recruitment of P-TEFb [50] and ii) our recent observations that ERα recruits P-TEFb to a region near the MYB SLR polyU and that this interaction is concordant with the accumulation of Ser2 CTD phosphorylated pol II bound to this region and the relief of MYB transcriptional attenuation [22]. This model also raises the possibility that the regulation of MYB may also involve the interaction of upstream bound NFκBp50/65 with the downstream intron 1 MYB SLR polyU. Recent data indicate that enhancer elements loop towards murine Myb intron 1 to bring the transcription apparatus to the vicinity of the pausing region and regulate Myb attenuation/elongation [19] and we have shown that the upstream regions of MYB lie in proximity to the MYB SLR polyU S5 Fig Furthermore, recent structure based analyses of HIV-1 LTR interactions suggest that pre-formed NFκBp50-DNA complexes can interact with downstream HIV TAR RNA [48].
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4390348&req=5

pone.0122919.g008: Model for the NFκBp50 and p65 regulation of MYB elongation through the intron 1 MYB SLR polyU region and upstream sequences.NFκBp50 binding at upstream sequences stimulates transcription from the multiple start sites. Transcripts are then paused/attenuated at the downstream MYB SLR polyU. In the absence of NFκBp65, NFκBp50 occupies the MYB SLR polyU region and MYB transcription is paused. In contrast the formation of a NFκBp50-p65 heterodimer on the MYB SLR polyU contributes to the stimulation of MYB transcription elongation by the NFκBp65-mediated recruitment of P-TEFb and the subsequent Ser2 phosphorylation of Pol II CTD (elongating form) by CDK9. This model is consistent with i) previous findings that NFκBp65 mediates transcriptional elongation through the direct recruitment of P-TEFb [50] and ii) our recent observations that ERα recruits P-TEFb to a region near the MYB SLR polyU and that this interaction is concordant with the accumulation of Ser2 CTD phosphorylated pol II bound to this region and the relief of MYB transcriptional attenuation [22]. This model also raises the possibility that the regulation of MYB may also involve the interaction of upstream bound NFκBp50/65 with the downstream intron 1 MYB SLR polyU. Recent data indicate that enhancer elements loop towards murine Myb intron 1 to bring the transcription apparatus to the vicinity of the pausing region and regulate Myb attenuation/elongation [19] and we have shown that the upstream regions of MYB lie in proximity to the MYB SLR polyU S5 Fig Furthermore, recent structure based analyses of HIV-1 LTR interactions suggest that pre-formed NFκBp50-DNA complexes can interact with downstream HIV TAR RNA [48].
Mentions: Previous studies have implicated NFκB family members in the regulation of transcriptional elongation through intron 1 of the murine MYB gene [23–25]. Notably, an NFκB enhancer element resides within intron 1 that is capable of binding NFκBp50, RelA, RelB and c-Rel in vitro [23–25]. In these studies, binding of NFκB complexes to this region was linked to the activation of endogenous MYB or MYB-CAT expression, suggesting that in case of the murine MYB gene transcriptional elongation through intron 1 is mediated by a DNA-dependent mechanism. Although the NFκB enhancer is potentially important to the regulation of the endogenous gene, it resides approximately 1.2 kbp downstream of the region investigated here and was excluded from the reporters examined in the current study. Nevertheless, this suggests that NFκBp50 may also contribute to the regulation of MYB via a region(s) upstream of the MYB SLR polyU. Consistent with this observation other reports have shown a role for a NFκB site found in the MYB promoter [49]. Collectively these observations suggest that NFκBp50 may regulate MYB through multiple regions/sites within the gene. In this case NFκBp50 bound at upstream sequences may stimulate transcription from the multiple start sites upstream of exon 1. Transcripts that are then stalled at the downstream MYB SLR polyU are released by the action of NFκBp50 at the MYB SLR polyU. In this way NFκBp50 may regulate MYB at at least two points within the gene using its nucleic acid binding activity (Fig 8).

Bottom Line: We identified a conserved lysine-rich motif within the Rel homology domain (RHD) of NFκBp50, mutation of which abrogated the interaction of NFκBp50 with the SLR polyU and impaired NFκBp50 mediated MYB elongation.Furthermore, we identify the DNA binding activity of NFκBp50 as a key component required for the SLR polyU mediated regulation of MYB.Collectively these results suggest that the MYB SLR polyU provides a platform for proteins to regulate MYB and reveals novel nucleic acid binding properties of NFκBp50 required for MYB regulation.

View Article: PubMed Central - PubMed

Affiliation: Differentiation and Transcription Laboratory, Peter MacCallum Cancer Centre, Locked Bag #1, Melbourne, Victoria, 8006, Australia; Sir Peter MacCallum Department of Oncology, The University of Melbourne, Parkville, Victoria, 3010, Australia.

ABSTRACT
MYB transcriptional elongation is regulated by an attenuator sequence within intron 1 that has been proposed to encode a RNA stem loop (SLR) followed by a polyU tract. We report that NFκBp50 can bind the SLR polyU RNA and promote MYB transcriptional elongation together with NFκBp65. We identified a conserved lysine-rich motif within the Rel homology domain (RHD) of NFκBp50, mutation of which abrogated the interaction of NFκBp50 with the SLR polyU and impaired NFκBp50 mediated MYB elongation. We observed that the TAR RNA-binding region of Tat is homologous to the NFκBp50 RHD lysine-rich motif, a finding consistent with HIV Tat acting as an effector of MYB transcriptional elongation in an SLR dependent manner. Furthermore, we identify the DNA binding activity of NFκBp50 as a key component required for the SLR polyU mediated regulation of MYB. Collectively these results suggest that the MYB SLR polyU provides a platform for proteins to regulate MYB and reveals novel nucleic acid binding properties of NFκBp50 required for MYB regulation.

No MeSH data available.


Related in: MedlinePlus