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Updated: Jan 11, 2026
Novel RNA-Binding Proteins Isolation by the RaPID Methodology
Published on: September 30, 2016
Cytoplasmic poly-adenosine binding proteins modulate susceptibility of mRNAs to RNA-binding protein-directed decay
Katherine M McKenney1, Carmen Hernandez-Perez1, Elise B Dunshee1
1Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis, MN 55455, USA.
Abstract:
The cytoplasmic fate of mRNAs is dictated by the balance of translation and mRNA degradation, governed in part by the 3' poly-adenosine tail and cytoplasmic poly(A)-binding proteins (PABPCs). Deadenylases remove poly(A) to initiate mRNA decay, while sequence-specific RNA-binding factors, including Pumilio proteins (PUM1 and PUM2), modulate these processes. We investigated how human PUM1&2 repress target mRNAs by accelerating their degradation. We found that the poly(A) tail plays a central role in PUM repression, dependent on the interplay of deadenylases and PABPCs. PUM-mediated repression requires the CCR4-NOT deadenylase but not the poly(A) nuclease (PAN). PUMs associate with and require PABPC1 and PABPC4 to repress. In the absence of PABPCs, both PUM targets and non-targets become unstable, bypassing PUM control. Increasing PABPC inhibits PUM activity in a concentration-dependent manner by stabilizing poly(A) mRNAs. Our results establish a Goldilocks principle wherein PABPC abundance tunes the response of mRNAs to regulatory factors through protection of poly(A) from deadenylation. Variation of PABPC levels across tissues and development suggests physiological relevance for this mechanism.
Insights
Pumilio proteins (PUM1&2) control mRNA degradation by interacting with poly(A)-binding proteins (PABPCs) and deadenylases. PABPC levels fine-tune mRNA stability, establishing a "Goldilocks principle" for gene regulation.
Area of Science:
- Molecular Biology
- Gene Regulation
- RNA Metabolism
Background:
- Cytoplasmic mRNA fate is determined by translation and degradation.
- The 3' poly-adenosine tail and poly(A)-binding proteins (PABPCs) are key regulators.
- Pumilio proteins (PUM1 and PUM2) are sequence-specific RNA-binding factors influencing mRNA decay.
Purpose of the Study:
- To investigate the mechanism by which human PUM1 and PUM2 repress target mRNAs.
- To elucidate the role of the poly(A) tail, deadenylases, and PABPCs in PUM-mediated repression.
Main Methods:
- Investigated PUM-mediated repression of target mRNAs.
- Assessed the requirement for deadenylases (CCR4-NOT, PAN) and PABPCs (PABPC1, PABPC4).
- Examined the effect of varying PABPC levels on PUM activity and mRNA stability.
Main Results:
- PUM repression requires the CCR4-NOT deadenylase but not PAN.
- PUMs associate with and require PABPC1 and PABPC4 for repression.
- PABPC absence destabilizes all mRNAs, bypassing PUM control.
- Increased PABPC inhibits PUM activity by stabilizing poly(A) mRNAs.
Conclusions:
- PUM-mediated mRNA decay is dependent on the interplay between deadenylases and PABPCs.
- PABPC abundance acts as a critical tuner, following a 'Goldilocks principle', to modulate mRNA responses to regulatory factors.
- This mechanism has physiological relevance due to varying PABPC levels across tissues and developmental stages.
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