Transcriptome-wide analysis links the short-term expression of the b isoforms of T-cell intracellular antigens to protective proteostasis-mediated survival and quiescence
Ontology highlight
ABSTRACT: Control of gene expression depends on genetics and environmental factors. The T-cell intracellular antigens T-cell intracellular antigen 1 (TIA1), TIA1-like/related protein (TIAL1/TIAR) and human antigen R (HuR/ELAVL1) are RNA-binding proteins that play crucial roles in regulating gene expression in both situations. This study used massive sequencing analysis to uncover molecular and functional mechanisms resulting from the short-time expression of the b isoforms of TIA1 and TIAR and HuR in HEK293 cells.
Project description:The knock down of T-cell intracellular antigen (TIA) proteins enhances the acquisition of aberrant cellular phenotypes promoting uncontrolled cell and tumor growth. Hereby, we report that inducible expression of either TIA1 or TIAR in human embryonic kidney (HEK293) cells represses cell proliferation. Mechanistically, the sustained expression of either TIA1 or TIAR protein abolishes endogenous TIA1/TIAR protein expression via regulating splicing of their own pre-mRNAs. This event is concomitant with cell cycle arrest and cell death by apoptosis. Based on genome-wide analysis of the transcript expression patterns in HuR-, TIA1- or TIAR-expressing HEK293 cells, we found regulatory links among the up-regulation on a select subset of p53 pathway genes involved in G1/S cell-cycle and apoptosis control. Finally, nude mice injected with TIA1- or TIAR-expressing HEK293 cells decrease, and even abolishing, the growth of tumor xenografts relative to control cells. Collectively, these observations show that TIA proteins can function as tumor suppressor genes. Two independent biological replicates were performed per sample type. Agilent SurePrint G3 Human Gene Expression 8x60K v2 array were used in all cases (single-channel hybridizations)
Project description:Background: Mice lacking either T-cell intracellular antigen 1 (TIA1) or TIA1-related/like protein (TIAR/TIAL1) show high rates of embryonic lethality, suggesting a relevant role for these proteins during embryonic development. However, intrinsic molecular and cellular consequences of either TIA1 or TIAR deficiency remain poorly defined. Results: By using genome-wide expression profiling approach, we demonstrate that either TIA1 or TIAR inactivation broadly alter normal development-associated signaling pathways in murine embryonic fibroblasts (MEF). Indeed, these analyses highlighted alterations of cytokine-cytokine and ECM-receptor interactions and Wnt, MAPK, TGF-beta dependent signaling pathways. Consistent with these results, TIA1 and TIAR knockout (KO) MEF show reduced rates of cell proliferation, cell cycle progression delay and increased cell size. Furthermore, TIA-proteins deficiency also caused metabolic deficiencies, increased ROS levels and DNA damage, promoting a gentle rise of cell death. Concomitantly, high rates of autophagy were detected in both TIA1 and TIAR KO MEF with induction of the formation of autophagosomes, as evidenced by the up-regulation of the LC3B protein, and autolysosomes, measured by colocalization of LC3B and LAMP1, as a survival mechanism attempt. Conclusions: Taken together, these observations support that TIA proteins orchestrate a transcriptome programme to activate specific developmental decisions. This program is likely to contribute to mouse physiology starting at early stages of the embryonic development. TIA1/TIAR might function as cell sensors to maintain homeostasis and promote adaptation/survival responses to developmental stress. Two independent replicates were performed for each experimental condition and hybridized to Agilent SurePrint G3 Mouse 8x60 microarrays.
Project description:The knock down of T-cell intracellular antigen (TIA) proteins enhances the acquisition of aberrant cellular phenotypes promoting uncontrolled cell and tumor growth. Hereby, we report that inducible expression of either TIA1 or TIAR in human embryonic kidney (HEK293) cells represses cell proliferation. Mechanistically, the sustained expression of either TIA1 or TIAR protein abolishes endogenous TIA1/TIAR protein expression via regulating splicing of their own pre-mRNAs. This event is concomitant with cell cycle arrest and cell death by apoptosis. Based on genome-wide analysis of the transcript expression patterns in HuR-, TIA1- or TIAR-expressing HEK293 cells, we found regulatory links among the up-regulation on a select subset of p53 pathway genes involved in G1/S cell-cycle and apoptosis control. Finally, nude mice injected with TIA1- or TIAR-expressing HEK293 cells decrease, and even abolishing, the growth of tumor xenografts relative to control cells. Collectively, these observations show that TIA proteins can function as tumor suppressor genes.
Project description:Background: Mice lacking either T-cell intracellular antigen 1 (TIA1) or TIA1-related/like protein (TIAR/TIAL1) show high rates of embryonic lethality, suggesting a relevant role for these proteins during embryonic development. However, intrinsic molecular and cellular consequences of either TIA1 or TIAR deficiency remain poorly defined. Results: By using genome-wide expression profiling approach, we demonstrate that either TIA1 or TIAR inactivation broadly alter normal development-associated signaling pathways in murine embryonic fibroblasts (MEF). Indeed, these analyses highlighted alterations of cytokine-cytokine and ECM-receptor interactions and Wnt, MAPK, TGF-beta dependent signaling pathways. Consistent with these results, TIA1 and TIAR knockout (KO) MEF show reduced rates of cell proliferation, cell cycle progression delay and increased cell size. Furthermore, TIA-proteins deficiency also caused metabolic deficiencies, increased ROS levels and DNA damage, promoting a gentle rise of cell death. Concomitantly, high rates of autophagy were detected in both TIA1 and TIAR KO MEF with induction of the formation of autophagosomes, as evidenced by the up-regulation of the LC3B protein, and autolysosomes, measured by colocalization of LC3B and LAMP1, as a survival mechanism attempt. Conclusions: Taken together, these observations support that TIA proteins orchestrate a transcriptome programme to activate specific developmental decisions. This program is likely to contribute to mouse physiology starting at early stages of the embryonic development. TIA1/TIAR might function as cell sensors to maintain homeostasis and promote adaptation/survival responses to developmental stress.
Project description:Background: Our recent studies strongly suggest that remodeling in the control of gene expression contributes to the progression of cell phenotypes associated to the transient and permanent knock-down of T-cell intracellular antigen 1(TIA1) and TIA1 related/like (TIAR/TIAL1) proteins. In particular, our studies have been focused on transcriptomic profiling of TIA-depleted HeLa cells using transient RNA interference (siRNA-mediated) and genome-wide microarray approaches Results: This study provides, for the first time, TIA1 and TIAR linked-transcriptomic analysis by using RNA-Seq next generation sequencing technology. Illumina RNA-Seq was used to survey transcriptome profiles from permanent TIA1 and TIAR-(shRNA-mediated) deficient HeLa cells. Analysis of the transcriptomes with the Cufflinks tool revealed that differentially expressed genes, isoforms produced by alternative splicing and/or promoter usage as well as microRNAs generated a great transcriptomic heterogeneity which might reflect the complexity linked to these cell phenoypes. The data of differential expression were validated by using genome-wide microarrays and QPCR. Gene Ontology and Kyoto Encyclopedia of Genes and Genomes term enrichment analysis revealed over-representation of genes associated with cell differentiation, multicellular organismal development, signal transduction, axon guidance and cell adhesion and under-representation of genes associated with positive regulation of migration, cell adhesion, response to organic substance, prostaglandin metabolic process and blood coagulation. Conclusions: Taken together, our observations point out towards an inhibitory role of TIA proteins in cell proliferation and growth, there appears to be an apparent molecular discrepancy regarding the effects of TIA proteins based on whether the proteins are depleted transiently (siRNA-mediated) or permanently (shRNA-mediated), suggesting the existence of clonal selection mechanisms of cellular populations in permanently TIA1/TIAR-depleted HeLa cells. For each cell type, three biological replicates were prepared and hybridized to Affymetrix GeneChips (HG U133plus2). 3+3 hybridizations in total for a single comparison KO vs WT.
Project description:Background: Our recent studies strongly suggest that remodeling in the control of gene expression contributes to the progression of cell phenotypes associated to the transient and permanent knock-down of T-cell intracellular antigen 1(TIA1) and TIA1 related/like (TIAR/TIAL1) proteins. In particular, our studies have been focused on transcriptomic profiling of TIA-depleted HeLa cells using transient RNA interference (siRNA-mediated) and genome-wide microarray approaches Results: This study provides, for the first time, TIA1 and TIAR linked-transcriptomic analysis by using RNA-Seq next generation sequencing technology. Illumina RNA-Seq was used to survey transcriptome profiles from permanent TIA1 and TIAR-(shRNA-mediated) deficient HeLa cells. Analysis of the transcriptomes with the Cufflinks tool revealed that differentially expressed genes, isoforms produced by alternative splicing and/or promoter usage as well as microRNAs generated a great transcriptomic heterogeneity which might reflect the complexity linked to these cell phenoypes. The data of differential expression were validated by using genome-wide microarrays and QPCR. Gene Ontology and Kyoto Encyclopedia of Genes and Genomes term enrichment analysis revealed over-representation of genes associated with cell differentiation, multicellular organismal development, signal transduction, axon guidance and cell adhesion and under-representation of genes associated with positive regulation of migration, cell adhesion, response to organic substance, prostaglandin metabolic process and blood coagulation. Conclusions: Taken together, our observations point out towards an inhibitory role of TIA proteins in cell proliferation and growth, there appears to be an apparent molecular discrepancy regarding the effects of TIA proteins based on whether the proteins are depleted transiently (siRNA-mediated) or permanently (shRNA-mediated), suggesting the existence of clonal selection mechanisms of cellular populations in permanently TIA1/TIAR-depleted HeLa cells.
Project description:Germinal centres (GC) are essential for the establishment of long-lasting antibody responses. In there, GC B cells rely on post-transcriptional RNA mechanisms for translating activation-associated transcriptional programs into functional changes in the cell proteome. However, we still lack knowledge about which are the critical proteins driving these key mechanisms. Here we show that the RNA binding proteins TIA1 and TIAL1 are required for the generation of long-lasting GC responses. TIA1 and TIAL1- deficient GC B cells fail to undergo antigen-mediated positive selection, expansion and differentiation into B cell clones producing high-affinity antibodies. Mechanistically, TIA1 and TIAL1 control the transcriptional identity of dark and light zone GC B cells and enable timely expression of the pro-survival molecule MCL1. Altogether, we demonstrate here that TIA1 and TIAL1 are key players in the post-transcriptional program that selects high-affinity antigen-specific GC B cells.
Project description:Germinal centres (GC) are essential for the establishment of long-lasting antibody responses. In there, GC B cells rely on post-transcriptional RNA mechanisms for translating activation-associated transcriptional programs into functional changes in the cell proteome. However, we still lack knowledge about which are the critical proteins driving these key mechanisms. Here we show that the RNA binding proteins TIA1 and TIAL1 are required for the generation of long-lasting GC responses. TIA1 and TIAL1- deficient GC B cells fail to undergo antigen- mediated positive selection, expansion and differentiation into B cell clones producing high-affinity antibodies. Mechanistically, TIA1 and TIAL1 control the transcriptional identity of dark and light zone GC B cells and enable timely expression of the pro-survival molecule MCL1. Altogether, we demonstrate here that TIA1 and TIAL1 are key players in the post-transcriptional program that selects high-affinity antigen-specific GC B cells.
Project description:B-cell lymphopoiesis requires dynamic modulation of the B-cell transcriptome at the post-transcriptional level, although the implication of RNA-binding proteins (RBPs) remain largely unknown. Here we show that the RBPs TIA1 and TIAL1 are essential in B cells and, if deleted, there is a developmental block at the pro-B cell stage. TIA1 and TIAL1 have redundant functions. They act together as global splicing regulators for the expression of mRNAs including those involved in DNA damage repair in pro-B cells. Mechanistically, TIA1 and TIAL1 bind to 5’splice sites for exon definition, splicing and expression of DNA damage sensors like Chek2 and Rif1. In their absence, pro-B cells show exacerbated DNA damage, altered P53 expression and increased cell death. Altogether, our study uncovers the importance of tight regulation of mRNA splicing by TIA1 and TIAL1 for the expression of integrative transcriptional programs for DNA damage sensing and repair during B-cell development.
Project description:B-cell lymphopoiesis requires dynamic modulation of the B-cell transcriptome at the post-transcriptional level, although the implication of RNA binding proteins (RBPs) remain largely unknown. Here we show that the RBPs TIA1 and TIAL1 are essential in B cells and, if deleted, there is a developmental block at the pro-B cell stage. TIA1 and TIAL1 have redundant functions. They act together as global splicing regulators for the expression of mRNAs including those involved in DNA damage repair in pro-B cells. Mechanistically, TIA1 and TIAL1 bind to 5’splice sites for exon definition, splicing and expression of DNA damage sensors like Chek2 and Rif1. In their absence, pro-B cells show exacerbated DNA damage, altered P53 expression and increased cell death. Altogether, our study uncovers the importance of tight regulation of mRNA splicing by TIA1 and TIAL1 for the expression of integrative transcriptional programs for DNA damage sensing and repair during B-cell development.