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Enhanced stability and polyadenylation of select mRNAs support rapid thermogenesis in the brown fat of a hibernator.

Grabek KR, Diniz Behn C, Barsh GS, Hesselberth JR, Martin SL - Elife (2015)

Bottom Line: A cohort of transcripts increased during torpor, paradoxical because transcription effectively ceases at these low temperatures.We show that this increase occurs not by elevated transcription but rather by enhanced stabilization associated with maintenance and/or extension of long poly(A) tails.This subset was enriched in a C-rich motif and genes required for BAT activation, suggesting a model and mechanism to prioritize translation of key proteins for thermogenesis.

View Article: PubMed Central - PubMed

Affiliation: Department of Cell and Developmental Biology, University of Colorado School of Medicine, Aurora, United States.

ABSTRACT
During hibernation, animals cycle between torpor and arousal. These cycles involve dramatic but poorly understood mechanisms of dynamic physiological regulation at the level of gene expression. Each cycle, Brown Adipose Tissue (BAT) drives periodic arousal from torpor by generating essential heat. We applied digital transcriptome analysis to precisely timed samples to identify molecular pathways that underlie the intense activity cycles of hibernator BAT. A cohort of transcripts increased during torpor, paradoxical because transcription effectively ceases at these low temperatures. We show that this increase occurs not by elevated transcription but rather by enhanced stabilization associated with maintenance and/or extension of long poly(A) tails. Mathematical modeling further supports a temperature-sensitive mechanism to protect a subset of transcripts from ongoing bulk degradation instead of increased transcription. This subset was enriched in a C-rich motif and genes required for BAT activation, suggesting a model and mechanism to prioritize translation of key proteins for thermogenesis.

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ePAT confirmation of RNA fractionation by poly(A) tail length.(A) A gel showing RT-PCR amplified CKB fromTVN (lane 2) and ePAT primed cDNA of one IBA, LT, SpW, and EAr short andlong poly(A) RNA samples (lanes 4–11; labeled along the top). A 50-bpladder is shown in lanes 1 and 3 (with M marked on top and several sizesdenoted to the left of lane 1). The TVN band marks the first 12 adenosinesof the poly(A) tail, while all other bands from ePAT cDNA represent thetotal length of the poly(A) tail. (B) The mean (+SEM)short and long poly(A) tail lengths calculated from the ePAT(-TVN) bandsizes of the samples within each RNA fraction. The short poly(A) tail isapproximately 26 bp, while the long poly(A) tail is approximately 48 bp.*p < 0.05 by two-tailed Student'st-test.DOI:http://dx.doi.org/10.7554/eLife.04517.009
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fig4s1: ePAT confirmation of RNA fractionation by poly(A) tail length.(A) A gel showing RT-PCR amplified CKB fromTVN (lane 2) and ePAT primed cDNA of one IBA, LT, SpW, and EAr short andlong poly(A) RNA samples (lanes 4–11; labeled along the top). A 50-bpladder is shown in lanes 1 and 3 (with M marked on top and several sizesdenoted to the left of lane 1). The TVN band marks the first 12 adenosinesof the poly(A) tail, while all other bands from ePAT cDNA represent thetotal length of the poly(A) tail. (B) The mean (+SEM)short and long poly(A) tail lengths calculated from the ePAT(-TVN) bandsizes of the samples within each RNA fraction. The short poly(A) tail isapproximately 26 bp, while the long poly(A) tail is approximately 48 bp.*p < 0.05 by two-tailed Student'st-test.DOI:http://dx.doi.org/10.7554/eLife.04517.009

Mentions: We considered three potential mechanisms that might explain increased transcriptabundance at low body temperature: (1) elevated transcription; (2) relativestabilization; and (3) acquisition of a poly(A) tail. To probe these mechanisms, wequantified abundance and the effect of poly(A) tail length on the dynamics ofRPPH1 and thirteen other transcripts, including three additionalncRNAs and ten mRNAs (Supplementary file 1A; note that there are two isoforms ofLIPE), during the torpor–arousal cycle. The absoluteabundance of these transcripts was measured by RT-qPCR in total RNA, and short and longpoly(A) RNA fractions (Figure 4—figuresupplement 1; Supplementary file 1A) from interbout aroused, late torpor, early arousal,and spring warm animals (n = 3). Two classes of RNA dynamics wereapparent; transcripts were either decreased (labeled as Class I) or stabilized (labeledas Class II) during torpor but not newly transcribed.


Enhanced stability and polyadenylation of select mRNAs support rapid thermogenesis in the brown fat of a hibernator.

Grabek KR, Diniz Behn C, Barsh GS, Hesselberth JR, Martin SL - Elife (2015)

ePAT confirmation of RNA fractionation by poly(A) tail length.(A) A gel showing RT-PCR amplified CKB fromTVN (lane 2) and ePAT primed cDNA of one IBA, LT, SpW, and EAr short andlong poly(A) RNA samples (lanes 4–11; labeled along the top). A 50-bpladder is shown in lanes 1 and 3 (with M marked on top and several sizesdenoted to the left of lane 1). The TVN band marks the first 12 adenosinesof the poly(A) tail, while all other bands from ePAT cDNA represent thetotal length of the poly(A) tail. (B) The mean (+SEM)short and long poly(A) tail lengths calculated from the ePAT(-TVN) bandsizes of the samples within each RNA fraction. The short poly(A) tail isapproximately 26 bp, while the long poly(A) tail is approximately 48 bp.*p < 0.05 by two-tailed Student'st-test.DOI:http://dx.doi.org/10.7554/eLife.04517.009
© Copyright Policy
Related In: Results  -  Collection

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Show All Figures
getmorefigures.php?uid=PMC4383249&req=5

fig4s1: ePAT confirmation of RNA fractionation by poly(A) tail length.(A) A gel showing RT-PCR amplified CKB fromTVN (lane 2) and ePAT primed cDNA of one IBA, LT, SpW, and EAr short andlong poly(A) RNA samples (lanes 4–11; labeled along the top). A 50-bpladder is shown in lanes 1 and 3 (with M marked on top and several sizesdenoted to the left of lane 1). The TVN band marks the first 12 adenosinesof the poly(A) tail, while all other bands from ePAT cDNA represent thetotal length of the poly(A) tail. (B) The mean (+SEM)short and long poly(A) tail lengths calculated from the ePAT(-TVN) bandsizes of the samples within each RNA fraction. The short poly(A) tail isapproximately 26 bp, while the long poly(A) tail is approximately 48 bp.*p < 0.05 by two-tailed Student'st-test.DOI:http://dx.doi.org/10.7554/eLife.04517.009
Mentions: We considered three potential mechanisms that might explain increased transcriptabundance at low body temperature: (1) elevated transcription; (2) relativestabilization; and (3) acquisition of a poly(A) tail. To probe these mechanisms, wequantified abundance and the effect of poly(A) tail length on the dynamics ofRPPH1 and thirteen other transcripts, including three additionalncRNAs and ten mRNAs (Supplementary file 1A; note that there are two isoforms ofLIPE), during the torpor–arousal cycle. The absoluteabundance of these transcripts was measured by RT-qPCR in total RNA, and short and longpoly(A) RNA fractions (Figure 4—figuresupplement 1; Supplementary file 1A) from interbout aroused, late torpor, early arousal,and spring warm animals (n = 3). Two classes of RNA dynamics wereapparent; transcripts were either decreased (labeled as Class I) or stabilized (labeledas Class II) during torpor but not newly transcribed.

Bottom Line: A cohort of transcripts increased during torpor, paradoxical because transcription effectively ceases at these low temperatures.We show that this increase occurs not by elevated transcription but rather by enhanced stabilization associated with maintenance and/or extension of long poly(A) tails.This subset was enriched in a C-rich motif and genes required for BAT activation, suggesting a model and mechanism to prioritize translation of key proteins for thermogenesis.

View Article: PubMed Central - PubMed

Affiliation: Department of Cell and Developmental Biology, University of Colorado School of Medicine, Aurora, United States.

ABSTRACT
During hibernation, animals cycle between torpor and arousal. These cycles involve dramatic but poorly understood mechanisms of dynamic physiological regulation at the level of gene expression. Each cycle, Brown Adipose Tissue (BAT) drives periodic arousal from torpor by generating essential heat. We applied digital transcriptome analysis to precisely timed samples to identify molecular pathways that underlie the intense activity cycles of hibernator BAT. A cohort of transcripts increased during torpor, paradoxical because transcription effectively ceases at these low temperatures. We show that this increase occurs not by elevated transcription but rather by enhanced stabilization associated with maintenance and/or extension of long poly(A) tails. Mathematical modeling further supports a temperature-sensitive mechanism to protect a subset of transcripts from ongoing bulk degradation instead of increased transcription. This subset was enriched in a C-rich motif and genes required for BAT activation, suggesting a model and mechanism to prioritize translation of key proteins for thermogenesis.

Show MeSH
Related in: MedlinePlus