Project description:Alternative splicing (AS) of pre-mRNA is utilized by higher eukaryotes to achieve increased transcriptome and proteomic complexity. The serine/arginine (SR) splicing factors regulate tissue- or cell type-specific AS in a concentration and phosphorylation dependent manner. However, the mechanisms that modulate the cellular levels of active SR proteins remain to be elucidated. In the present study, we provide evidence for a role for the long nuclear-retained regulatory RNA (nrRNA), MALAT1 in AS regulation. MALAT1 interacts with SR proteins and influences the distribution of these and other splicing factors in nuclear speckle domains. Depletion of MALAT1 changes AS of endogenous pre-mRNAs, similar to what was observed upon overexpression of SR proteins. Furthermore, MALAT1 regulates cellular levels of phosphorylated forms of SR proteins. Taken together, our results suggest that MALAT1 regulates AS by modulating the levels of active SR proteins. Our results further highlight a novel role for a nrRNA in the regulation of gene expression. Malat1 Antisense and control knockdowns evaluated on a microarray platform to profile alternative splicing levels for 5782 cassette-type alternative exons.
Project description:Alternative splicing (AS) of pre-mRNA is utilized by higher eukaryotes to achieve increased transcriptome and proteomic complexity. The serine/arginine (SR) splicing factors regulate tissue- or cell type-specific AS in a concentration and phosphorylation dependent manner. However, the mechanisms that modulate the cellular levels of active SR proteins remain to be elucidated. In the present study, we provide evidence for a role for the long nuclear-retained regulatory RNA (nrRNA), MALAT1 in AS regulation. MALAT1 interacts with SR proteins and influences the distribution of these and other splicing factors in nuclear speckle domains. Depletion of MALAT1 changes AS of endogenous pre-mRNAs, similar to what was observed upon overexpression of SR proteins. Furthermore, MALAT1 regulates cellular levels of phosphorylated forms of SR proteins. Taken together, our results suggest that MALAT1 regulates AS by modulating the levels of active SR proteins. Our results further highlight a novel role for a nrRNA in the regulation of gene expression.
Project description:The long noncoding MALAT1 RNA is upregulated in cancer tissues and its elevated expression is associated with hyper-proliferation, but the underlying mechanism is poorly understood. We demonstrate that MALAT1 levels are regulated during normal cell cycle progression. Genome-wide transcriptome analyses in normal human diploid fibroblasts reveal that MALAT1 modulates the expression of cell cycle genes, and is required for G1/S and mitotic progression. Depletion of MALAT1 leads to activation of p53 and its target genes. The cell cycle defects observed in MALAT1-depleted cells are sensitive to p53 levels, indicating that p53 is a major downstream mediator of MALAT1 activity. Furthermore, MALAT1-depleted cells display reduced expression of B-MYB (Mybl2), an oncogenic transcription factor involved in G2/M progression, due to altered binding of splicing factors on B-MYB pre-mRNA and aberrant alternative splicing. In human cells, MALAT1 promotes cellular proliferation by modulating the expression and/or premRNA processing of cell cycle-regulated transcription factors. These findings provide mechanistic insights on the role of MALAT1 in regulating cellular proliferation. Keywords: MALAT1; MALAT-1, NEAT2, ncRNA; E2F, alternative splicing; pre-mRNA splicing factors WI38 cells (normal human diploid fibroblasts) were transfected with a control oligo (CTR) or antisense oligos to MALAT1 and RNA was isolated after 48 hr. Two antisense oligos were use for MALAT1 (AS-1 and AS-2). Arrays were done for 3 sets of samples in triplicate (control, AS-1 and AS-2).
Project description:Malat1 is an abundant long noncoding RNA that localizes to nuclear bodies known as nuclear speckles, which contain a distinct set of pre-mRNA processing factors. Previous in vitro studies have demonstrated that Malat1 interacts with pre-mRNA splicing factors, including the serine- and arginine-rich (SR) family of proteins, and regulates a variety of biological processes, including cancer cell migration, synapse formation, cell cycle progression, and responses to serum stimulation. To address the physiological function of Malat1 in a living organism, we generated Malat1-KO (KO) mice using homologous recombination. Unexpectedly, the Malat1-KO mice were viable and fertile, showing no apparent phenotypes. Nuclear speckle markers were also correctly localized in cells that lacked Malat1. However, the cellular levels of another long noncoding RNA, Neat1, which is an architectural component of nuclear bodies known as paraspeckles, were downregulated in a particular set of tissues and cells lacking Malat1. To address if the the absence of Malat1 affects the expression of other genes, including other long noncoding RNA, microarrays were used to study the impact of knocking-out Malat1 on global gene expression in mouse embryonic fibroblasts (MEFs). MEFs were prepared from E13.5 mouse embryos from wildtype and Malat1 knock-out mice. RNA harvested from these cells were hybridized to Affymetirx mouse gene expression array.
Project description:The long noncoding MALAT1 RNA is upregulated in cancer tissues and its elevated expression is associated with hyper-proliferation, but the underlying mechanism is poorly understood. We demonstrate that MALAT1 levels are regulated during normal cell cycle progression. Genome-wide transcriptome analyses in normal human diploid fibroblasts reveal that MALAT1 modulates the expression of cell cycle genes, and is required for G1/S and mitotic progression. Depletion of MALAT1 leads to activation of p53 and its target genes. The cell cycle defects observed in MALAT1-depleted cells are sensitive to p53 levels, indicating that p53 is a major downstream mediator of MALAT1 activity. Furthermore, MALAT1-depleted cells display reduced expression of B-MYB (Mybl2), an oncogenic transcription factor involved in G2/M progression, due to altered binding of splicing factors on B-MYB pre-mRNA and aberrant alternative splicing. In human cells, MALAT1 promotes cellular proliferation by modulating the expression and/or premRNA processing of cell cycle-regulated transcription factors. These findings provide mechanistic insights on the role of MALAT1 in regulating cellular proliferation. Keywords: MALAT1; MALAT-1, NEAT2, ncRNA; E2F, alternative splicing; pre-mRNA splicing factors
Project description:Transcriptome analysis of control and MALAT1 lncRNA-depleted RNA samples from human diploid lung fibroblasts [WI38] The long noncoding MALAT1 RNA is upregulated in cancer tissues and its elevated expression is associated with hyper-proliferation, but the underlying mechanism is poorly understood. We demonstrate that MALAT1 levels are regulated during normal cell cycle progression. Genome-wide transcriptome analyses in normal human diploid fibroblasts reveal that MALAT1 modulates the expression of cell cycle genes, and is required for G1/S and mitotic progression. Depletion of MALAT1 leads to activation of p53 and its target genes. The cell cycle defects observed in MALAT1-depleted cells are sensitive to p53 levels, indicating that p53 is a major downstream mediator of MALAT1 activity. Furthermore, MALAT1-depleted cells display reduced expression of B-MYB (Mybl2), an oncogenic transcription factor involved in G2/M progression, due to altered binding of splicing factors on B-MYB pre-mRNA and aberrant alternative splicing. In human cells, MALAT1 promotes cellular proliferation by modulating the expression and/or pre-mRNA processing of cell cycle-regulated transcription factors. These findings provide mechanistic insights on the role of MALAT1 in regulating cellular proliferation. We analyzed RNA from control and MALAT1 depleted WI38 cells using the Affymetrix Human Exon 1.0 ST platform. Array data was analyzed by Partek Genomic Suite software.
Project description:Malat1 is an abundant long noncoding RNA that localizes to nuclear bodies known as nuclear speckles, which contain a distinct set of pre-mRNA processing factors. Previous in vitro studies have demonstrated that Malat1 interacts with pre-mRNA splicing factors, including the serine- and arginine-rich (SR) family of proteins, and regulates a variety of biological processes, including cancer cell migration, synapse formation, cell cycle progression, and responses to serum stimulation. To address the physiological function of Malat1 in a living organism, we generated Malat1-KO (KO) mice using homologous recombination. Unexpectedly, the Malat1-KO mice were viable and fertile, showing no apparent phenotypes. Nuclear speckle markers were also correctly localized in cells that lacked Malat1. However, the cellular levels of another long noncoding RNA, Neat1, which is an architectural component of nuclear bodies known as paraspeckles, were downregulated in a particular set of tissues and cells lacking Malat1. To address if the absence of Malat1 affects the expression of other genes, including other long noncoding RNA, microarrays were used to study the impact of knocking-out Malat1 on global gene expression in hippocampal neurons. Hippocampi were dissected from two sets of wildtype and Malat1 knock-out mice and RNA from these neurons were hybridized to Affymetix mouse exon array. Individual animals from each pairs of wildtype and knock-out are littermates.
Project description:Pre-mRNA splicing is regulated by developmental and environmental cues, but little is known about how specific signals are transduced in mammalian cells to regulate this critical gene expression step. Here, we report massive reprogramming of alternative splicing in response to EGF signaling. By blocking individual branches in EGF signaling, we found that Akt activation plays a major role, while other branches, such as the JAK/STAT and ERK pathways, make minor contributions to EGF-induced splicing. Activated Akt next branches to the SRPK family of kinases specific for SR proteins, rather than mTOR, by inducing SRPK autophosphorylation that switches the splicing kinases from Hsp70- to Hsp90-containing complexes. This leads to enhanced SRPK nuclear translocation and SR protein phosphorylation. These findings reveal a major signal transduction pathway for regulated splicing and place SRPKs in a central position in the pathway, consistent with their reputed roles in a large number of human cancers. Examination of EGF induced AKT-SRPK-SR pathway in the regulation of splicing in HEK293T cells with RASL-seq
Project description:Since we found an upregulation of the long non coding RNA MALAT1 in Multiple Sclerosis (MS) patients, we decided to explore the global effect of MALAT1 modulation on transcriptome. We hence performed high-coverage RNA-seq experiments of MALAT1 knockdown in Jurkat E6-1 T cells to analyze gene expression, alternative splicing (AS), and backsplicing profiles. We found 107 differentially expressed genes, 1114 dysregulated AS events, and 49 circular RNAs that were modulated by MALAT1. These results highlighted the role of MALAT1 in splicing and backsplicing regulation.
Project description:CC-671 has been identified as an inhibitor of Cdc2-like kinase 2 (CLK2) and TTK in direct enzyme assays. CLK2 is a member of the CLK family that phosphorylates serine- and arginine-rich (SR) proteins of the spliceosomal complex as part of a regulatory mechanism for control of pre-mRNA splicing. SR proteins are a family of small nuclear ribonucleoprotein particle (snRNP) splicing factors involved in constitutive and alternative splicing. Monitoring specific phospho-biomarkers of CLK2 demonstrated that CC-671 inhibited phosphorylation of CLK2 substrates in cancer cells with mean IC50 of 549 nM in the triple negative breast cancer (TNBC) line CAL51. In this study, RNA sequencing approach was used to quantify the impact of CC-671 treatment on gene transcription and global alternative splicing in CAL51 cells. Differential exon usage analysis demonstrated that CC-671 changed alternative splicing of many genes. In addition, different sets of genes are impacted by CC-671 at both the alternative splicing and mRNA expression. Genes impacted by alternative splicing shared a set of common pathways with genes altered by mRNA expression. This result indicates that CC-671 regulates transcription via both gene expression and alternative splicing mechanisms.