Project description:Tight control of β cell mRNA translation plays a central role in regulating glucose homoeostasis and β cell health. RNA binding proteins (RBPs) impact translational dynamics and function in networks to achieve their regulatory outcomes, yet an understanding of the RBPs and nature of their interplay in directing β cell translation remain limited. We recently established that the RBP PCBP2 is a key post-transcriptional regulator of β cell function. Here, we investigate the relationship of PCBP2 and its sister-isoform PCBP1 in shaping β cell homeostasis and translation. Pcbp co-deletion in primary β cells gave rise to a severe diabetic phenotype due to compromised β cell viability. Single-cell RNA sequencing of Pcbp co-deficient β cells revealed downregulation of a network of core translation initiation factors and ribosomal mRNAs. Motif enrichment analysis, mRNA-protein interaction, and mRNA stability studies identified that the PCBPs co-impact these mRNAs in part through binding and stabilization. Accordingly, protein translational monitoring demonstrated a requirement for the PCBPs in sustaining global mRNA translation in β cells. Together, these findings demonstrate a requirement for the PCBPs in sustaining the global rates of mRNA translation critical for β cell control of glucose homeostasis.
Project description:RNA-binding proteins participate in a complex array of post-transcriptional controls essential to cell-type specification and somatic development. Despite their detailed biochemical characterizations, the degree to which each RNA-binding protein impacts on mammalian embryonic development remains incompletely defined and the level of functional redundancy among subsets of these proteins remains open to question. The poly-(C) binding proteins, Pcbp's (aCPs, hnRNPEs), are encoded by a highly conserved and broadly expressed gene family. The two major Pcbp isoforms, Pcbp2 and Pcbp1, are robustly expressed in a wide range of tissues and exert both nuclear and cytoplasmic controls over gene expression. Here we report that Pcbp1-null embryos are rendered nonviable in the peri-implantation stage. In contrast, Pcbp2-null embryos survive until mid-gestation at which time they undergo a loss in viability associated with cardiovascular and hematopoietic abnormalities. Adult mice heterozygous for either Pcbp1 or Pcbp2 null alleles display a mild and non-disruptive growth defect. These data reveal that Pcbp1 and Pcbp2 are individually essential for mouse embryonic development and post-natal growth, reveal a non-redundant in vivo role for Pcpb2 in hematopoiesis, and provide direct evidence that Pcbp1, a retrotransposed derivative of Pcpb2, has evolved essential function(s) in the mammalian genome. mRNA-seq on fetal liver tissue from 12.5 days post coitum. 4 replicates of WT and 3 replicates of PCBP2 Knockout
Project description:To explore potential functional implications of isoform usage shifts, we examined the effect of PCBP1/PCBP2 expression in human AC16 cardiac cells. PCBP1/PCBP2 are KH-domain-containing RNA-binding proteins (RBP) that have been implicated in transcriptional, post-transcriptional and translational regulations. How PCBP1 and PCBP2 are functionally differentiated remains a subject of interest and few reports have outlined their function in cardiac cells. The two paralogs share close homology (~85% identical sequences) and partially overlapping RNA binding targets, suggesting they may form mutually regulatory relationships. Human and mouse PCBP1 sequences share 100.0% identity, whereas human and mouse PCBP2 are identical except in 5 positions; therefore we expressed the human/mouse PCBP1 and human PCBP2 coding sequences in human AC16 cardiac cells. Immunofluorescence imaging confirms broad cytonuclear localization of both paralogs under overexpression. The cells were then subjected to RNA sequencing to determine the effects of PCBP1/2 on gene expression.
Project description:RNA-binding proteins participate in a complex array of post-transcriptional controls essential to cell-type specification and somatic development. Despite their detailed biochemical characterizations, the degree to which each RNA-binding protein impacts on mammalian embryonic development remains incompletely defined and the level of functional redundancy among subsets of these proteins remains open to question. The poly-(C) binding proteins, Pcbp’s (aCPs, hnRNPEs), are encoded by a highly conserved and broadly expressed gene family. The two major Pcbp isoforms, Pcbp2 and Pcbp1, are robustly expressed in a wide range of tissues and exert both nuclear and cytoplasmic controls over gene expression. Here we report that Pcbp1-null embryos are rendered nonviable in the peri-implantation stage. In contrast, Pcbp2-null embryos survive until mid-gestation at which time they undergo a loss in viability associated with cardiovascular and hematopoietic abnormalities. Adult mice heterozygous for either Pcbp1 or Pcbp2 null alleles display a mild and non-disruptive growth defect. These data reveal that Pcbp1 and Pcbp2 are individually essential for mouse embryonic development and post-natal growth, reveal a non-redundant in vivo role for Pcpb2 in hematopoiesis, and provide direct evidence that Pcbp1, a retrotransposed derivative of Pcpb2, has evolved essential function(s) in the mammalian genome.
Project description:E14.5 fetal liver cells from CD-1 mice were enriched for hematopoietic progenitors. The purified hematopoietic progenitor cells were infected immediately with retroviruses encoding shRNAs that target Pcbp1, Pcbp2, as well as two sets of control shRNAs; Luciferase and scrambled sequence. The transduced cells were grown for 48 hours. These cells were collected (‘Day 0’ cells), or washed and resuspended in differentiation medium and incubated for an additional 2 days (‘Day 2’ cells). 1ug of total RNA isolated from ‘Day 0’ and ‘Day 2’ cells from each Pcbp1 or Pcbp2 depleted sample was used for cDNA library construction after polyA selection. A total of 9 samples were generated from each of the two time points: 3 controls; Pcbp1 knockdowns with three distinctly targeting shRNAs (sh1,3,4); Pcbp2 knockdown with three distinctly targeting shRNAs (sh1,3,4). Sequencing was carried out using a 150nt paired-end sequencing protocol.
Project description:Defining the molecular mechanisms that impact T cell maturation and function is important because abnormalities in these processes can lead to immunodeficient states or autoimmunity. RNA-binding proteins (RBPs) have emerged as critical factors in thymopoiesis, immune cell lineage commitment and maintenance, and as modulators of immune responses. The RBP paralogs Pcbp1 and Pcbp2 are widely expressed in the innate and adaptive immune systems and are each essential for mouse development. Pcbp1 has been shown to prevent conversion of CD4+ effector T cells into Foxp3+ regulatory T cells (Treg), with loss of Pcbp1 resulting in increased Treg differentiation. To determine whether Pcbp2 also is required for CD4+ T cell development and function, we derived mice with conditional Pcbp2 deletion in CD4+ T cells and assessed their overall phenotype and proliferative responses to activating stimuli. We found that Pcbp2 is essential for CD4+ T conventional cell (Tconv) proliferation, working through regulation of CD4 receptor co-stimulatory signaling. In addition, our data demonstrate a clear association between Pcbp2 control of Runx1 exon 6 splicing in CD4+ T cells and a specific role for Pcbp2 in the maintenance of peripheral CD4+ lymphocyte population size. Pcbp2 deficiency in the CD4+ lineage did not impact Treg abundance in vivo or function in vitro. Last, we show that Pcbp2 function is required for optimal in vivo Tconv cell activation in a T cell adoptive transfer colitis model system. These data lead us to conclude that Pcbp2 is a critical regulator of T cell signaling and function in the CD4+ lineage.
Project description:Activation of p53 by the small molecule Nutlin can result in a combination of cell cycle arrest and apoptosis. The relative strength of these events is difficult to predict, leaving uncertainty as to the therapeutic benefits of Nutlin. Here, we report a new translation control mechanism shaping p53-dependent apoptosis. We performed polysomal profiling in the cell lines SJSA1 and HCT116, of which only the first undergoes robust cell death in response to p53 activation by Nutlin. We establish Nutlin-induced apoptosis in SJSA1 cells to be associated with a set of translationally enhanced mRNAs carrying a newly identified 3’UTR motif which we labeled CG-motif. We identified PCBP2 and DHX30 as interactor proteins of the CG-motif that are more abundant in HCT116 cells compared to SJSA1. The binding of DHX30 to the CG-motif detected in HCT116 cells was shown to be dependent on PCBP2. Interestingly, DHX30 depletion enhances polysome association of CG-motif mRNAs in HCT116 cells, shifting their outcome towards apoptosis. In U2OS, an osteosarcoma-derived cell line that unlike SJSA1 undergoes persistent cell cycle arrest in response to Nutlin, DHX30 is highly expressed and its depletion enhances the expression of CG-motif mRNAs.