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Alternative Polyadenylation Releases PCBP1-Mediated Suppression of CFIm25 During Macrophage Differentiation
María Del Pilar Mendoza Martín1, Salwa Mohd Mostafa2, Atish Barua2
1Francisco de Vitoria University, Madrid, Spain.
Abstract:
CFIm25, a key component of the CFIm complex needed for mRNA 3' end processing, shows increased protein expression during monocyte-to-macrophage differentiation despite stable mRNA levels. We demonstrate that PCBP1 suppresses CFIm25 translation in monocytes by binding to its long 3'UTR. During differentiation, alternative polyadenylation generates a shorter CFIm25 3'UTR lacking PCBP1 binding sites. RNA immunoprecipitation confirms PCBP1 binding to the long 3'UTR, while ribosome association analysis shows enhanced translation without this interaction. PCBP1 knockdown increases CFIm25 protein specifically in undifferentiated cells and induces macrophage differentiation markers without stimulation. These findings reveal how alternative polyadenylation controls CFIm25 expression during immune cell differentiation by modulating RNA-binding protein interactions and provide insight into post-transcriptional regulation of RNA processing factors.
Insights
Poly(rC)-binding protein 1 (PCBP1) controls CFIm25 protein levels by binding to its 3' untranslated region (UTR). Alternative polyadenylation shortens the CFIm25 3'UTR during immune cell differentiation, enhancing translation and protein expression.
Area of Science:
- Molecular Biology
- Immunology
- RNA Biology
Background:
- CFIm25 is crucial for mRNA 3' end processing and its protein levels rise during monocyte-to-macrophage differentiation.
- This increase occurs despite stable CFIm25 mRNA levels, suggesting post-transcriptional regulation.
Purpose of the Study:
- To investigate the post-transcriptional mechanisms regulating CFIm25 protein expression during monocyte differentiation.
- To identify the role of RNA-binding proteins and alternative polyadenylation in controlling CFIm25 levels.
Main Methods:
- RNA immunoprecipitation (RIP) to confirm protein-RNA interactions.
- Ribosome association analysis to assess translational efficiency.
- PCBP1 knockdown experiments in monocytes.
Main Results:
- PCBP1 binds to the long 3' untranslated region (UTR) of CFIm25 mRNA, suppressing its translation in monocytes.
- Alternative polyadenylation generates a shorter CFIm25 3'UTR during differentiation, losing PCBP1 binding sites.
- This leads to enhanced CFIm25 translation and increased protein levels.
- PCBP1 knockdown increases CFIm25 protein in undifferentiated cells and promotes macrophage differentiation markers.
Conclusions:
- Alternative polyadenylation of CFIm25 mRNA is a key regulatory mechanism controlling its protein expression during immune cell differentiation.
- Modulation of RNA-binding protein interactions, specifically PCBP1, by alternative polyadenylation impacts CFIm25 levels.
- This study provides insights into the post-transcriptional regulation of RNA processing factors in immune cell development.
