scholarly journals AIRE Recruits P-TEFb for Transcriptional Elongation of Target Genes in Medullary Thymic Epithelial Cells

2007 ◽  
Vol 27 (24) ◽  
pp. 8815-8823 ◽  
Author(s):  
Irena Oven ◽  
Naděžda Brdičková ◽  
Jiri Kohoutek ◽  
Tomaž Vaupotič ◽  
Mojca Narat ◽  
...  
Keyword(s):  
Epithelial Cells ◽  
Rna Polymerase ◽  
Rna Polymerase Ii ◽  
Target Genes ◽  
Ectopic Expression ◽  
Lymphocytic Infiltration ◽  
Salivary Protein ◽  
Thymic Epithelial Cells ◽  
Transcriptional Elongation ◽  
Medullary Thymic Epithelial Cells

ABSTRACT AIRE is a transcriptional activator that directs the ectopic expression of many tissue-specific genes in medullary thymic epithelial cells, which plays an important role in the negative selection of autoreactive T cells. However, its mechanism of action remains poorly understood. In this study, we found that AIRE regulates the step of elongation rather than initiation of RNA polymerase II. For these effects, AIRE bound and recruited P-TEFb to target promoters in medullary thymic epithelial cells. In these cells, AIRE activated the ectopic transcription of insulin and salivary protein 1 genes. Indeed, by chromatin immunoprecipitation, we found that RNA polymerase II was already engaged on these promoters but was unable to elongate in the absence of AIRE. Moreover, the genetic inactivation of cyclin T1 from P-TEFb abolished the transcription of AIRE-responsive genes and led to lymphocytic infiltration of lacrimal and salivary glands in the CycT1−/− mouse. Our findings reveal critical steps by which AIRE regulates the transcription of genes that control central tolerance in the thymus.

scholarly journals Interaction between P-TEFb and the C-Terminal Domain of RNA Polymerase II Activates Transcriptional Elongation from Sites Upstream or Downstream of Target Genes

2002 ◽  
Vol 22 (1) ◽  
pp. 321-331 ◽  
Author(s):  
Ran Taube ◽  
Xin Lin ◽  
Dan Irwin ◽  
Koh Fujinaga ◽  
B. Matija Peterlin
Keyword(s):  
Rna Polymerase ◽  
Rna Polymerase Ii ◽  
Target Genes ◽  
Elongation Factor ◽  
Transcriptional Elongation ◽  
Cyclin T1 ◽  
Positive Transcription Elongation Factor ◽  
Terminal Domain ◽  
Activation Of Transcription

ABSTRACT Transcriptional elongation by RNA polymerase II (RNAPII) is regulated by the positive transcription elongation factor b (P-TEFb). P-TEFb is composed of Cdk9 and C-type cyclin T1 (CycT1), CycT2a, CycT2b, or CycK. The role of the C-terminal region of CycT1 and CycT2 remains unknown. In this report, we demonstrate that these sequences are essential for the activation of transcription by P-TEFb via DNA, i.e., when CycT1 is tethered upstream or downstream of promoters and coding sequences. A histidine-rich stretch, which is conserved between CycT1 and CycT2 in this region, bound the C-terminal domain of RNAPII. This binding was required for the subsequent expression of full-length transcripts from target genes. Thus, P-TEFb could mediate effects of enhancers on the elongation of transcription.

scholarly journals HIF-1 Interacts with TRIM28 and DNA-PK to release paused RNA polymerase II and activate target gene transcription in response to hypoxia

2022 ◽  
Vol 13 (1) ◽  
Author(s):  
Yongkang Yang ◽  
Haiquan Lu ◽  
Chelsey Chen ◽  
Yajing Lyu ◽  
Robert N. Cole ◽  
...  
Keyword(s):  
Breast Cancer ◽  
Rna Polymerase ◽  
Rna Polymerase Ii ◽  
Gene Transcription ◽  
Target Genes ◽  
Large Subunit ◽  
Hypoxia Inducible Factor ◽  
Elongation Factor ◽  
Transcriptional Elongation ◽  
Pol Ii

AbstractHypoxia-inducible factor-1 (HIF-1) is a transcription factor that acts as a regulator of oxygen (O2) homeostasis in metazoan species by binding to hypoxia response elements (HREs) and activating the transcription of hundreds of genes in response to reduced O2 availability. RNA polymerase II (Pol II) initiates transcription of many HIF target genes under non-hypoxic conditions but pauses after approximately 30–60 nucleotides and requires HIF-1 binding for release. Here we report that in hypoxic breast cancer cells, HIF-1 recruits TRIM28 and DNA-dependent protein kinase (DNA-PK) to HREs to release paused Pol II. We show that HIF-1α and TRIM28 assemble the catalytically-active DNA-PK heterotrimer, which phosphorylates TRIM28 at serine-824, enabling recruitment of CDK9, which phosphorylates serine-2 of the Pol II large subunit C-terminal domain as well as the negative elongation factor to release paused Pol II, thereby stimulating productive transcriptional elongation. Our studies reveal a molecular mechanism by which HIF-1 stimulates gene transcription and reveal that the anticancer effects of drugs targeting DNA-PK in breast cancer may be due in part to their inhibition of HIF-dependent transcription.

scholarly journals Aire controls the differentiation program of thymic epithelial cells in the medulla for the establishment of self-tolerance

2008 ◽  
Vol 205 (12) ◽  
pp. 2827-2838 ◽  
Author(s):  
Masashi Yano ◽  
Noriyuki Kuroda ◽  
Hongwei Han ◽  
Makiko Meguro-Horike ◽  
Yumiko Nishikawa ◽  
...  
Keyword(s):  
Epithelial Cells ◽  
Fluorescent Protein ◽  
Morphological Changes ◽  
Cell Types ◽  
Salivary Protein ◽  
Epidermal Differentiation ◽  
Thymic Epithelial Cells ◽  
Reactive Protein ◽  
Medullary Thymic Epithelial Cells ◽  
Green Fluorescent

The roles of autoimmune regulator (Aire) in the expression of the diverse arrays of tissue-restricted antigen (TRA) genes from thymic epithelial cells in the medulla (medullary thymic epithelial cells [mTECs]) and in organization of the thymic microenvironment are enigmatic. We approached this issue by creating a mouse strain in which the coding sequence of green fluorescent protein (GFP) was inserted into the Aire locus in a manner allowing concomitant disruption of functional Aire protein expression. We found that Aire+ (i.e., GFP+) mTECs were the major cell types responsible for the expression of Aire-dependent TRA genes such as insulin 2 and salivary protein 1, whereas Aire-independent TRA genes such as C-reactive protein and glutamate decarboxylase 67 were expressed from both Aire+ and Aire− mTECs. Remarkably, absence of Aire from mTECs caused morphological changes together with altered distribution of mTECs committed to Aire expression. Furthermore, we found that the numbers of mTECs that express involucrin, a marker for terminal epidermal differentiation, were reduced in Aire-deficient mouse thymus, which was associated with nearly an absence of Hassall's corpuscle-like structures in the medulla. Our results suggest that Aire controls the differentiation program of mTECs, thereby organizing the global mTEC integrity that enables TRA expression from terminally differentiated mTECs in the thymic microenvironment.

scholarly journals Myasthenia gravis-specific aberrant neuromuscular gene expression by medullary thymic epithelial cells in thymoma

2021 ◽  
Author(s):  
Yoshiaki Yasumizu ◽  
Naganari Ohkura ◽  
Hisashi Murata ◽  
Makoto Kinoshita ◽  
Soichiro Funaki ◽  
...  
Keyword(s):  
Epithelial Cells ◽  
Myasthenia Gravis ◽  
Interaction Analysis ◽  
Ectopic Expression ◽  
Cell Interaction ◽  
Thymic Epithelial Cells ◽  
Autoantibody Production ◽  
Dendritic Cell Migration ◽  
Associated Proteins ◽  
Medullary Thymic Epithelial Cells

Myasthenia gravis (MG) is a neurological disease caused by autoantibodies against neuromuscular-associated proteins. While MG is frequently developed in thymoma patients, the etiologic factors for MG are not well understood. Here, by constructing a comprehensive atlas of thymoma using bulk and single-cell RNA-seq, we identified ectopic expression of neuromuscular molecules in MG-associated thymoma (MG-thymoma). These molecules were originated from a distinct subpopulation of medullary thymic epithelial cells (mTECs), which we named neuromuscular mTECs (nmTECs). MG-thymoma also exhibited microenvironments dedicated to autoantibody production, including ectopic germinal center formation, T follicular helper cell accumulation, and type 2 conventional dendritic cell migration. Cell-cell interaction analysis also predicted the interaction between nmTECs and T/B cells via CXCL12-CXCR4. The enrichment of nmTECs presenting neuromuscular molecules within MG-thymoma was further confirmed by immunohistochemically and by cellular composition estimation from MG-thymoma transcriptome. Altogether, this study suggests that nmTECs play a significant role in MG pathogenesis via ectopic expression of neuromuscular molecules.

scholarly journals Lymphotoxin β Receptor Regulates the Development of CCL21-Expressing Subset of Postnatal Medullary Thymic Epithelial Cells

2013 ◽  
Vol 190 (10) ◽  
pp. 5110-5117 ◽  
Author(s):  
Enkhsaikhan Lkhagvasuren ◽  
Mie Sakata ◽  
Izumi Ohigashi ◽  
Yousuke Takahama
Keyword(s):  
Epithelial Cells ◽  
Thymic Epithelial Cells ◽  
Medullary Thymic Epithelial Cells ◽  
Β Receptor

Identification of rpo30, a vaccinia virus RNA polymerase gene with structural similarity to a eucaryotic transcription elongation factor

1990 ◽  
Vol 10 (10) ◽  
pp. 5433-5441
Author(s):  
B Y Ahn ◽  
P D Gershon ◽  
E V Jones ◽  
B Moss
Keyword(s):  
Rna Polymerase ◽  
Vaccinia Virus ◽  
Rna Polymerase Ii ◽  
Elongation Factor ◽  
Viral Rna ◽  
In Vitro Translation ◽  
Virus Protein ◽  
Transcriptional Elongation

Eucaryotic transcription factors that stimulate RNA polymerase II by increasing the efficiency of elongation of specifically or randomly initiated RNA chains have been isolated and characterized. We have identified a 30-kilodalton (kDa) vaccinia virus-encoded protein with apparent homology to SII, a 34-kDa mammalian transcriptional elongation factor. In addition to amino acid sequence similarities, both proteins contain C-terminal putative zinc finger domains. Identification of the gene, rpo30, encoding the vaccinia virus protein was achieved by using antibody to the purified viral RNA polymerase for immunoprecipitation of the in vitro translation products of in vivo-synthesized early mRNA selected by hybridization to cloned DNA fragments of the viral genome. Western immunoblot analysis using antiserum made to the vaccinia rpo30 protein expressed in bacteria indicated that the 30-kDa protein remains associated with highly purified viral RNA polymerase. Thus, the vaccinia virus protein, unlike its eucaryotic homolog, is an integral RNA polymerase subunit rather than a readily separable transcription factor. Further studies showed that the expression of rpo30 is regulated by dual early and later promoters.

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