Polypyrimidine tract binding proteins are essential for B cell development
- The Babraham Institute, United Kingdom
- Goethe University Frankfurt, Germany
- University of Cambridge, United Kingdom
Abstract
Polypyrimidine Tract Binding Protein 1 (PTBP1) is a RNA-binding protein (RBP) expressed throughout B cell development. Deletion of Ptbp1 in mouse pro-B cells results in upregulation of PTBP2 and normal B cell development. We show that PTBP2 compensates for PTBP1 in B cell ontogeny as deletion of both Ptbp1 and Ptbp2 results in a complete block at the pro-B cell stage and a lack of mature B cells. In pro-B cells PTBP1 ensures precise synchronisation of the activity of cyclin dependent kinases at distinct stages of the cell cycle, suppresses S-phase entry and promotes progression into mitosis. PTBP1 controls mRNA abundance and alternative splicing of important cell cycle regulators including CYCLIN-D2, c-MYC, p107 and CDC25B. Our results reveal a previously unrecognised mechanism mediated by a RBP that is essential for B cell ontogeny and integrates transcriptional and post-translational determinants of progression through the cell cycle.
Data availability
mRNAseq libraries and iCLIP analysis generated in this study have been deposited in GEO and can be accessed with the GSE136882 accession code at GEO. Mitogen-activated primary B cell mRNAseq libraries were previously reported and can be accessed with the GSM1520115, GSM1520116, GSM1520117and GSM1520118 accession codes in GEO.
-
Polypyrimidine tract binding proteins are essential for B cell developmentNCBI Gene Expression Omnibus, GSE136882.
-
HuR- dependent regulation of mRNA splicing is essential for the B cell antibody responseNCBI Gene Expression Omnibus, GSE62129.
-
PTBP1 and PTBP2 Repress Nonconserved Cryptic ExonsNCBI BioProject, PRJNA309732.
Article and author information
Author details
Christopher WJ Smith
Funding
Biotechnology and Biological Sciences Research Council (BB/J00152X/1)
- Martin Turner
Biotechnology and Biological Sciences Research Council (BB/P01898X/1)
- Elisa Monzón-Casanova
- Martin Turner
Biotechnology and Biological Sciences Research Council (BBS/E/B/000C0407)
- Martin Turner
Biotechnology and Biological Sciences Research Council (BBS/E/B/000C0427)
- Martin Turner
Wellcome (200823/Z/16/Z)
- Martin Turner
European Cooperation in Science and Technology (CA17103)
- Elisa Monzón-Casanova
The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.
Ethics
Animal experimentation: Mice were bred and maintained in the Babraham Institute Biological Support Unit. Since the opening of this barrier facility (2009), no primary pathogens or additional agents listed in the FELASA recommendations have been confirmed during health monitoring surveys of the stock holding rooms. Ambient temperature was ~19-21{degree sign}C and relative humidity 52%. Lighting was provided on a 12-hour light: 12-hour dark cycle including 15 min 'dawn' and 'dusk' periods of subdued lighting. After weaning, mice were transferred to individually ventilated cages with 1-5 mice per cage. Mice were fed CRM (P) VP diet (Special Diet Services) ad libitum and received seeds (e.g. sunflower, millet) at the time of cage-cleaning as part of their environmental enrichment. All mouse experimentation was approved by the Babraham Institute Animal Welfare and Ethical Review Body (UK Home Office Project Licence /P4D4AF812). Animal husbandry and experimentation complied with existing European Union and United Kingdom Home Office legislation and local standards.
Copyright
© 2020, Monzón-Casanova et al.
This article is distributed under the terms of the Creative Commons Attribution License permitting unrestricted use and redistribution provided that the original author and source are credited.
Metrics
-
- 2,725
- views
-
- 333
- downloads
-
- 29
- citations
Views, downloads and citations are aggregated across all versions of this paper published by eLife.
Download links
A two-part list of links to download the article, or parts of the article, in various formats.
Downloads (link to download the article as PDF)
Open citations (links to open the citations from this article in various online reference manager services)
Cite this article (links to download the citations from this article in formats compatible with various reference manager tools)
Polypyrimidine tract binding proteins are essential for B cell development
eLife 9:e53557.
https://doi.org/10.7554/eLife.53557
Further reading
-
- Chromosomes and Gene Expression
Specialized magnetic beads that bind target proteins to a cryogenic electron microscopy grid make it possible to study the structure of protein complexes from dilute samples.
-
- Chromosomes and Gene Expression
- Structural Biology and Molecular Biophysics
Type II nuclear receptors (T2NRs) require heterodimerization with a common partner, the retinoid X receptor (RXR), to bind cognate DNA recognition sites in chromatin. Based on previous biochemical and overexpression studies, binding of T2NRs to chromatin is proposed to be regulated by competition for a limiting pool of the core RXR subunit. However, this mechanism has not yet been tested for endogenous proteins in live cells. Using single-molecule tracking (SMT) and proximity-assisted photoactivation (PAPA), we monitored interactions between endogenously tagged RXR and retinoic acid receptor (RAR) in live cells. Unexpectedly, we find that higher expression of RAR, but not RXR, increases heterodimerization and chromatin binding in U2OS cells. This surprising finding indicates the limiting factor is not RXR but likely its cadre of obligate dimer binding partners. SMT and PAPA thus provide a direct way to probe which components are functionally limiting within a complex TF interaction network providing new insights into mechanisms of gene regulation in vivo with implications for drug development targeting nuclear receptors.
