The Carboxy-terminal domain (CTD) of RNA Polymerase II (RNAPII) in mammals undergoes extensive post-translational modification, which is essential for transcriptional initiation and elongation. Here, we show that the CTD of RNAPII is methylated at a single arginine (R1810) by the transcriptional co-activator CARM1. Although methylation at R1810 is present on the hyper-phosphorylated form of RNAPII in vivo, Ser-2 or Ser-5 phosphorylation inhibit CARM1 activity towards this site in vitro, suggesting that methylation occurs before transcription initiation. Mutation of R1810 results in the mis-expression of a variety of snRNAs and snoRNAs, an effect that is also observed in Carm1-/- MEFs. These results demonstrate that CTD methylation facilitates the expression of select RNAs, perhaps serving to discriminate the RNAPII-associated machinery recruited to distinct gene types. Overall design: To address the function of RNAPII methylation, we generated Raji cell lines expressing an RNA Polymerase II resistant to a-amanitin and carrying either wild-type R1810 or an arginine to alanine substitution at that same residue, abolishing R1810 methylation of the CTD. In cells cultured in a-amanitin, the a-amanitin-resistant mutants fully replaced the functions of endogenous RNAPII, allowing us to study if gene-expression is affected by the absence of R1810me
The C-terminal domain of RNA polymerase II is modified by site-specific methylation.
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View SamplesThe MYC transcription factor is a master regulator of diverse cancer pathways and somatic cell reprogramming. MYC is a compelling therapeutic target that exhibits cancer-specific cellular effects. Pharmacologic inhibition of MYC function has proven challenging due to its numerous modes of forced expression and the difficulty of disrupting protein-DNA interactions. Here we demonstrate the rapid and potent abrogation of MYC gene transcription by representative small molecule bromodomain inhibitors of the BET family of chromatin adaptors. This transcriptional suppression of MYC was observed in the context of the natural, chromosomally translocated, and amplified gene locus. Inhibition of BET bromodomain-promoter interactions and subsequent reduction of MYC transcript and protein levels resulted in G1 arrest and extensive apoptosis in a variety of leukemia and lymphoma cell lines. Exogenous expression of MYC from an artificial promoter that is resistant to BET regulation significantly protected cells from growth suppression by BET inhibitors and revealed that MYC exerts a direct and tight control of key pro-growth and anti-apoptotic target genes. Transcriptional profiling of two cells after 4 and 8 hours of treatment with BET inhibitor shows that both MYC and its targets are strongly down-regulated. We thus demonstrate that pharmacologic inhibition of MYC is achievable through targeting BET bromodomains, and suggest that such inhibitors may have broad clinical applicability given the widespread pathogenetic role of MYC in cancer.
Targeting MYC dependence in cancer by inhibiting BET bromodomains.
Cell line, Treatment
View SamplesSmall molecule inhibitors of the bromodomain and extraterminal (BET) family of proteins are in clinical trials for a variety of cancers, but patient selection strategies are limited. This is due in part to the heterogeneity of response following BET inhibition (BETi), which includes differentiation, senescence, and cell death in subsets of cancer cell lines. To elucidate the dominant features defining response to BETi, we carried out phenotypic and gene expression analysis of both treatment naïve cell lines and engineered tolerant lines. We found that both de novo and acquired tolerance to BET inhibition are driven by the robustness of the apoptotic response and that genetic or pharmacological manipulation of the apoptotic signaling network can modify the phenotypic response to BETi. We further identify that ordered expression of the apoptotic genes BCL2, BCL2L1, and BAD significantly predicts response to BETi. Our findings highlight the role of the apoptotic network in response to BETi, providing a molecular basis for patient stratification and combination therapies. Overall design: Gene expression profiling of A375 melanoma cells or NOMO-1 AML cells treated with DMSO or the BET inhibitor, CPI203. Also, gene expression profiling of the respective derived BETi-tolerant cells treated with DMSO or CPI203.
Preclinical Anticancer Efficacy of BET Bromodomain Inhibitors Is Determined by the Apoptotic Response.
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View SamplesSel1L is an adaptor protein for the E3 ligase Hrd1 involved in endoplasmic reticulum-associated degradation (ERAD). Its physiological importance in mammalian ERAD, however, remains to be established. Here, using the inducible Sel1L knockout mouse and cell models, we provide the first in vivo evidence that Sel1L is indispensable for Hrd1 stability, ER homeostasis and survival. Acute loss of Sel1L leads to premature death in adult mice within 3 weeks with profound pancreatic atrophy. Contrary to current belief, our data show that mammalian Sel1L is required for Hrd1 stability and ERAD function both in vitro and in vivo. Sel1L deficiency disturbs ER homeostasis, activates ER stress, attenuates translation and promotes cell death. Serendipitously, using biochemical approach coupled with mass spectrometry, we found that Sel1L deficiency causes the aggregation of both small and large ribosomal subunits. Thus, Sel1L is an indispensable component of mammalian ERAD and ER homeostasis, which is essential for protein translation, pancreatic function, cellular and organismal survival.
Sel1L is indispensable for mammalian endoplasmic reticulum-associated degradation, endoplasmic reticulum homeostasis, and survival.
Specimen part
View SamplesCell-based models of many neurological and psychiatric diseases, established by reprogramming patient somatic cells into human induced pluripotent stem cells (hiPSCs), have now been reported. While numerous reports have demonstrated that neuronal cells differentiated from hiPSCs are electrophysiologically active mature neurons, the age of these cells relative to cells in the human brain remains unresolved. Comparisons of gene expression profiles of hiPSC-derived neural progenitor cells (NPCs) and neurons to the Allen BrainSpan Atlas indicate that hiPSC neural cells most resemble first trimester neural tissue. Consequently, we posit that hiPSC-derived neural cells may most accurately be used to model the early developmental defects that contribute to disease predisposition rather than the late features of the disease. Though the characteristic symptoms of schizophrenia (SCZD) generally appear late in adolescence, it is now thought to be a neurodevelopmental condition, often predated by a prodromal period that can appear in early childhood. Postmortem studies of SCZD brain tissue typically describe defects in mature neurons, such as reduced neuronal size and spine density in the prefrontal cortex and hippocampus, but abnormalities of neuronal organization, particularly in the cortex, have also been reported. We postulated that defects in cortical organization in SCZD might result from abnormal migration of neural cells. To test this hypothesis, we directly reprogrammed fibroblasts from SCZD patients into hiPSCs and subsequently differentiated these disorder-specific hiPSCs into NPCs. SCZD hiPSC differentiated into forebrain NPCs have altered expression of a number of cellular adhesion genes, reduced WNT signaling and aberrant cellular migration.
Phenotypic differences in hiPSC NPCs derived from patients with schizophrenia.
Sex, Specimen part, Disease, Disease stage
View SamplesEndoplasmic reticulum-associated degradation (ERAD) represents a principle quality control (QC) mechanism to clear misfolded proteins in the ER; however, its physiological significance and the nature of endogenous ERAD substrates remain largely unknown. Here we discover that IRE1alpha, the sensor of unfolded protein response (UPR), is a bona fide substrate of the Sel1L-Hrd1 ERAD complex. Mechanistically, ERAD-mediated IRE1alpha degradation occurs in a Bip-dependent manner under basal conditions and is attenuated in response to ER stress. Both intramembrane hydrophilic residues of IRE1alpha and lectin protein OS9 are required for IRE1alpha degradation. ERAD deficiency causes IRE1alpha protein stabilization, accumulation and mild activation both in vitro and in vivo, leading to cellular hypersensitivity to ER stress and inflammation. Furthermore, though enterocyte-specific Sel1L-knockout mice (Sel1LIEC) are viable and appear normal, they are more susceptible to experimental colitis in an IRE1alpha-dependent but CHOP-independent manner. Collectively, these results demonstrate that Sel1L-Hrd1 ERAD serves a distinct, essential function in restraint of IRE1alpha signaling in vivo by managing its protein turnover.
IRE1α is an endogenous substrate of endoplasmic-reticulum-associated degradation.
Sex, Age, Specimen part
View SamplesGenome-wide gene expression changes in response to CBP inhibitor treatment in Treg cells using RNA sequencing (RNA-seq). Overall design: Expression profiling by RNA-seq of Treg cells treated with DMSO or CBP inhibitor
Regulatory T Cell Modulation by CBP/EP300 Bromodomain Inhibition.
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View SamplesGenome-wide gene expression changes in response to CBP inhibitor treatment in Treg cells using microarray.
Regulatory T Cell Modulation by CBP/EP300 Bromodomain Inhibition.
Cell line, Treatment
View SamplesIt is fundamentally unknown how normal cellular processes or responses to extracellular stimuli may invoke polyadenylation and degradation of ncRNA substrates or if human disease processes exhibit defects in polyadenylation of ncRNA substrates as part of their pathogenesis. Our results demonstrate that mononuclear cells from subjects with relapsing-remitting multiple sclerosis (RRMS) exhibit pervasive increases in levels of polyadenylated ncRNAs including Y1 RNA, 18S and 28S rRNA, and U1, U2, and U4 snRNAs and these defects are unique to RRMS. Defects in expression of both Ro60 and La proteins in RRMS appear to contribute to increased polyadenylation of ncRNAs. Further, IFN-ß1b, a common RRMS therapy, restores both Ro60 and La levels to normal as well as levels of polyadenylated Y1 RNA and U1 snRNA suggesting that aberrant polyadenylation of ncRNA substrates may have pathogenic consequences. Overall design: We extracted RNA from peripheral whole blood in healthy control subjects and patients with established relapsing-remitting multiple sclerosis using PaxGene tubes.
Defective structural RNA processing in relapsing-remitting multiple sclerosis.
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View SamplesTo improve our understanding of lncRNA expression in T cells, we used whole genome sequencing (RNA-seq) to identify lncRNAs expressed in human T cells and those selectively expressed in T cells differentiated under TH1, TH2, or TH17 polarizing conditions. The majority of these lineage-specific lncRNAs are co-expressed with lineage-specific protein-coding genes. These lncRNAs are predominantly intragenic with co-expressed protein-coding genes and are transcribed in sense and antisense orientations with approximately equal frequencies. Further, genes encoding TH lineage specific mRNAs are not randomly distributed across the genome but are highly enriched in the genome in genomic regions also containing genes encoding TH lineage-specific lncRNAs. Our analyses also identify a cluster of antisense lncRNAs transcribed from the RAD50 locus that are selectively expressed under TH2 polarizing conditions and co-expressed with IL4, IL5 and IL13 genes. Depletion of these lncRNAs via selective siRNA treatment demonstrates the critical requirement of these lncRNAs for expression of the TH2 cytokines, IL-4, IL-5 and IL-13. Collectively, our analyses identify new lncRNAs expressed in a TH lineage specific manner and identify a critical role for a cluster of lncRNAs for expression of genes encoding TH2 cytokines. Overall design: Human peripheral blood mononuclear cells (PBMC) were cultured under TH1, TH2, and TH17 polarizing conditions. TH1, TH2, and TH17 primary and effector cultures were isolated and poly(A)+ and total RNA sequencing performed.
Expression and functions of long noncoding RNAs during human T helper cell differentiation.
No sample metadata fields
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