Publications by authors named "Emmanuel Compe"

23 Publications

  • Page 1 of 1

CDK7 and MITF repress a transcription program involved in survival and drug tolerance in melanoma.

EMBO Rep 2021 Jul 23:e51683. Epub 2021 Jul 23.

Institut de Génétique et de Biologie Moléculaire et Cellulaire, Equipe Labélisée Ligue contre le Cancer, Strasbourg, France.

Melanoma cell phenotype switching between differentiated melanocytic and undifferentiated mesenchymal-like states drives metastasis and drug resistance. CDK7 is the serine/threonine kinase of the basal transcription factor TFIIH. We show that dedifferentiation of melanocytic-type melanoma cells into mesenchymal-like cells and acquisition of tolerance to targeted therapies is achieved through chronic inhibition of CDK7. In addition to emergence of a mesenchymal-type signature, we identify a GATA6-dependent gene expression program comprising genes such as AMIGO2 or ABCG2 involved in melanoma survival or targeted drug tolerance, respectively. Mechanistically, we show that CDK7 drives expression of the melanocyte lineage transcription factor MITF that in turn binds to an intronic region of GATA6 to repress its expression in melanocytic-type cells. We show that GATA6 expression is activated in MITF-low melanoma cells of patient-derived xenografts. Taken together, our data show how the poorly characterized repressive function of MITF in melanoma participates in a molecular cascade regulating activation of a transcriptional program involved in survival and drug resistance in melanoma.
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http://dx.doi.org/10.15252/embr.202051683DOI Listing
July 2021

Reduced levels of prostaglandin I synthase: a distinctive feature of the cancer-free trichothiodystrophy.

Proc Natl Acad Sci U S A 2021 Jun;118(26)

Istituto di Genetica Molecolare L.L. Cavalli Sforza, Consiglio Nazionale delle Ricerche, 27100 Pavia, Italy;

The cancer-free photosensitive trichothiodystrophy (PS-TTD) and the cancer-prone xeroderma pigmentosum (XP) are rare monogenic disorders that can arise from mutations in the same genes, namely or Both XPD and XPB proteins belong to the 10-subunit complex transcription factor IIH (TFIIH) that plays a key role in transcription and nucleotide excision repair, the DNA repair pathway devoted to the removal of ultraviolet-induced DNA lesions. Compelling evidence suggests that mutations affecting the DNA repair activity of TFIIH are responsible for the pathological features of XP, whereas those also impairing transcription give rise to TTD. By adopting a relatives-based whole transcriptome sequencing approach followed by specific gene expression profiling in primary fibroblasts from a large cohort of TTD or XP cases with mutations in gene, we identify the expression alterations specific for TTD primary dermal fibroblasts. While most of these transcription deregulations do not impact on the protein level, very low amounts of prostaglandin I synthase (PTGIS) are found in TTD cells. PTGIS catalyzes the last step of prostaglandin I synthesis, a potent vasodilator and inhibitor of platelet aggregation. Its reduction characterizes all TTD cases so far investigated, both the PS-TTD with mutations in TFIIH coding genes as well as the nonphotosensitive (NPS)-TTD. A severe impairment of TFIIH and RNA polymerase II recruitment on the promoter is found in TTD but not in XP cells. Thus, PTGIS represents a biomarker that combines all PS- and NPS-TTD cases and distinguishes them from XP.
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http://dx.doi.org/10.1073/pnas.2024502118DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8255998PMC
June 2021

The Long Road to Understanding RNAPII Transcription Initiation and Related Syndromes.

Annu Rev Biochem 2021 Jun;90:193-219

Institut de Génétique et de Biologie Moléculaire et Cellulaire, CNRS, INSERM, Université de Strasbourg, 67404 Illkirch CEDEX, Commune Urbaine de Strasbourg, France; email:

In eukaryotes, transcription of protein-coding genes requires the assembly at core promoters of a large preinitiation machinery containing RNA polymerase II (RNAPII) and general transcription factors (GTFs). Transcription is potentiated by regulatory elements called enhancers, which are recognized by specific DNA-binding transcription factors that recruit cofactors and convey, following chromatin remodeling, the activating cues to the preinitiation complex. This review summarizes nearly five decades of work on transcription initiation by describing the sequential recruitment of diverse molecular players including the GTFs, the Mediator complex, and DNA repair factors that support RNAPII to enable RNA synthesis. The elucidation of the transcription initiation mechanism has greatly benefited from the study of altered transcription components associated with human diseases that could be considered transcription syndromes.
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http://dx.doi.org/10.1146/annurev-biochem-090220-112253DOI Listing
June 2021

A PKD-MFF signaling axis couples mitochondrial fission to mitotic progression.

Cell Rep 2021 May;35(7):109129

Institut de Génétique et de Biologie Moléculaire et Cellulaire (IGBMC), Illkirch, France; Centre National de la Recherche Scientifique UMR 7104, Strasbourg, France; Institut National de la Santé et de la Recherche Médicale U964, Strasbourg, France; Université de Strasbourg, Strasbourg, France. Electronic address:

Mitochondria are highly dynamic organelles subjected to fission and fusion events. During mitosis, mitochondrial fission ensures equal distribution of mitochondria to daughter cells. If and how this process can actively drive mitotic progression remains largely unknown. Here, we discover a pathway linking mitochondrial fission to mitotic progression in mammalian cells. The mitochondrial fission factor (MFF), the main mitochondrial receptor for the Dynamin-related protein 1 (DRP1), is directly phosphorylated by Protein Kinase D (PKD) specifically during mitosis. PKD-dependent MFF phosphorylation is required and sufficient for mitochondrial fission in mitotic but not in interphasic cells. Phosphorylation of MFF is crucial for chromosome segregation and promotes cell survival by inhibiting adaptation of the mitotic checkpoint. Thus, PKD/MFF-dependent mitochondrial fission is critical for the maintenance of genome integrity during cell division.
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http://dx.doi.org/10.1016/j.celrep.2021.109129DOI Listing
May 2021

Dysregulation of LXR responsive genes contribute to ichthyosis in trichothiodystrophy.

J Dermatol Sci 2020 Mar 24;97(3):201-207. Epub 2020 Jan 24.

Institut de Génétique et de Biologie Moléculaire et Cellulaire, CNRS/INSERM/Université de Strasbourg, Strasbourg, France. Electronic address:

Background: Trichothiodystrophy (TTD) is a rare autosomal recessive disorder characterised by brittle hairs and various systemic symptoms, including photosensitivity and ichthyosis. While photosensitivity could result from DNA repair defects, other TTD clinical features might be due to deficiencies in certain molecular processes.

Objectives: The aim of this study was to understand the pathophysiological mechanism of ichthyosis in TTD, focused on the transcriptional dysregulation.

Methods: TTD mouse skin tissue and keratinocytes were pathologically and physiologically examined to identify the alteration of lipid homeostasis in TTD with ichtyosis. Gene expression of certain lipid transporter was assessed in fibroblasts derived from TTD patients and TTD mouse keratinocytes.

Results: Histopathology and electron microscopy revealed abnormal lipid composition in TTD mice skin. In addition to abnormal cholesterol dynamics, TTD mouse keratinocytes exhibit impaired expression of Liver X receptor (LXR) responsive genes, including Abca12, a key regulator of Harlequin ichthyosis, and Abcg1 that is involved in the cholesterol transport process in the epidermis. Strikingly, dysregulation of LXR responsive genes has been only observed in cells isolated from TTD patients who developed ichthyosis.

Conclusions: Our results suggest that the altered expression of the LXR-responsive genes contribute to the pathophysiology of ichthyosis in TTD. These findings provide a new drug discovery target for TTD.
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http://dx.doi.org/10.1016/j.jdermsci.2020.01.012DOI Listing
March 2020

TFIIE orchestrates the recruitment of the TFIIH kinase module at promoter before release during transcription.

Nat Commun 2019 05 7;10(1):2084. Epub 2019 May 7.

Department of Functional Genomics and Cancer, IGBMC, CNRS/INSERM/University of Strasbourg, BP 163, 67404, Illkirch Cedex, C. U. Strasbourg, France.

In eukaryotes, the general transcription factors TFIIE and TFIIH assemble at the transcription start site with RNA Polymerase II. However, the mechanism by which these transcription factors incorporate the preinitiation complex and coordinate their action during RNA polymerase II transcription remains elusive. Here we show that the TFIIEα and TFIIEβ subunits anchor the TFIIH kinase module (CAK) within the preinitiation complex. In addition, we show that while RNA polymerase II phosphorylation and DNA opening occur, CAK and TFIIEα are released from the promoter. This dissociation is impeded by either ATP-γS or CDK7 inhibitor THZ1, but still occurs when XPB activity is abrogated. Finally, we show that the Core-TFIIH and TFIIEβ are subsequently removed, while elongation factors such as DSIF are recruited. Remarkably, these early transcriptional events are affected by TFIIE and TFIIH mutations associated with the developmental disorder, trichothiodystrophy.
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http://dx.doi.org/10.1038/s41467-019-10131-1DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6504876PMC
May 2019

Lurbinectedin Specifically Triggers the Degradation of Phosphorylated RNA Polymerase II and the Formation of DNA Breaks in Cancer Cells.

Mol Cancer Ther 2016 10 14;15(10):2399-2412. Epub 2016 Sep 14.

Department of Functional Genomics and Cancer, IGBMC, CNRS/INSERM/University of Strasbourg, C. U. Strasbourg, France.

We have defined the mechanism of action of lurbinectedin, a marine-derived drug exhibiting a potent antitumor activity across several cancer cell lines and tumor xenografts. This drug, currently undergoing clinical evaluation in ovarian, breast, and small cell lung cancer patients, inhibits the transcription process through (i) its binding to CG-rich sequences, mainly located around promoters of protein-coding genes; (ii) the irreversible stalling of elongating RNA polymerase II (Pol II) on the DNA template and its specific degradation by the ubiquitin/proteasome machinery; and (iii) the generation of DNA breaks and subsequent apoptosis. The finding that inhibition of Pol II phosphorylation prevents its degradation and the formation of DNA breaks after drug treatment underscores the connection between transcription elongation and DNA repair. Our results not only help to better understand the high specificity of this drug in cancer therapy but also improve our understanding of an important transcription regulation mechanism. Mol Cancer Ther; 15(10); 2399-412. ©2016 AACR.
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http://dx.doi.org/10.1158/1535-7163.MCT-16-0172DOI Listing
October 2016

Nucleotide Excision Repair and Transcriptional Regulation: TFIIH and Beyond.

Annu Rev Biochem 2016 Jun;85:265-90

Institut de Génétique et de Biologie Moléculaire et Cellulaire, Centre National de la Recherche Scientifique/Institut National de la Santé et de la Recherche Médicale/Université de Strasbourg, 67404 Illkirch Cedex, Commune Urbaine Strasbourg, France; email: ,

Transcription factor IIH (TFIIH) is a multiprotein complex involved in both transcription and DNA repair, revealing a striking functional link between these two processes. Some of its subunits also belong to complexes involved in other cellular processes, such as chromosome segregation and cell cycle regulation, emphasizing the multitasking capabilities of this factor. This review aims to depict the structure of TFIIH and to dissect the roles of its subunits in different cellular mechanisms. Our understanding of the biochemistry of TFIIH has greatly benefited from studies focused on diseases related to TFIIH mutations. We address the etiology of these disorders and underline the fact that TFIIH can be considered a promising target for therapeutic strategies.
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http://dx.doi.org/10.1146/annurev-biochem-060815-014857DOI Listing
June 2016

TFIIH-dependent MMP-1 overexpression in trichothiodystrophy leads to extracellular matrix alterations in patient skin.

Proc Natl Acad Sci U S A 2015 Feb 20;112(5):1499-504. Epub 2015 Jan 20.

Istituto di Genetica Molecolare Consiglio Nazionale delle Ricerche, Pavia 27100, Italy;

Mutations in the XPD subunit of the DNA repair/transcription factor TFIIH result in distinct clinical entities, including the cancer-prone xeroderma pigmentosum (XP) and the multisystem disorder trichothiodystrophy (TTD), which share only cutaneous photosensitivity. Gene-expression profiles of primary dermal fibroblasts revealed overexpression of matrix metalloproteinase 1 (MMP-1), the gene encoding the metalloproteinase that degrades the interstitial collagens of the extracellular matrix (ECM), in TTD patients mutated in XPD compared with their healthy parents. The defect is observed in TTD and not in XP and is specific for fibroblasts, which are the main producers of dermal ECM. MMP-1 transcriptional up-regulation in TTD is caused by an erroneous signaling mediated by retinoic acid receptors on the MMP-1 promoter and leads to hypersecretion of active MMP-1 enzyme and degradation of collagen type I in the ECM of cell/tissue systems and TTD patient skin. In agreement with the well-known role of ECM in eliciting signaling events controlling cell behavior and tissue homeostasis, ECM alterations in TTD were shown to impact on the migration and wound-healing properties of patient dermal fibroblasts. The presence of a specific inhibitor of MMP activity was sufficient to restore normal cell migration, thus providing a potential approach for therapeutic strategies. This study highlights the relevance of ECM anomalies in TTD pathogenesis and in the phenotypic differences between TTD and XP.
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http://dx.doi.org/10.1073/pnas.1416181112DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4321311PMC
February 2015

Dynamic partnership between TFIIH, PGC-1α and SIRT1 is impaired in trichothiodystrophy.

PLoS Genet 2014 Oct 23;10(10):e1004732. Epub 2014 Oct 23.

Institut de Génétique et de Biologie Moléculaire et Cellulaire, Illkirch, Strasbourg, France.

The expression of protein-coding genes requires the selective role of many transcription factors, whose coordinated actions remain poorly understood. To further grasp the molecular mechanisms that govern transcription, we focused our attention on the general transcription factor TFIIH, which gives rise, once mutated, to Trichothiodystrophy (TTD), a rare autosomal premature-ageing disease causing inter alia, metabolic dysfunctions. Since this syndrome could be connected to transcriptional defects, we investigated the ability of a TTD mouse model to cope with food deprivation, knowing that energy homeostasis during fasting involves an accurate regulation of the gluconeogenic genes in the liver. Abnormal amounts of gluconeogenic enzymes were thus observed in TTD hepatic parenchyma, which was related to the dysregulation of the corresponding genes. Strikingly, such gene expression defects resulted from the inability of PGC1-α to fulfill its role of coactivator. Indeed, extensive molecular analyses unveiled that wild-type TFIIH cooperated in an ATP-dependent manner with PGC1-α as well as with the deacetylase SIRT1, thereby contributing to the PGC1-α deacetylation by SIRT1. Such dynamic partnership was, however, impaired when TFIIH was mutated, having as a consequence the disruption of PGC1-α recruitment to the promoter of target genes. Therefore, besides a better understanding of the etiology of TFIIH-related disease, our results shed light on the synergistic relationship that exist between different types of transcription factors, which is necessary to properly regulate the expression of protein coding genes.
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http://dx.doi.org/10.1371/journal.pgen.1004732DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4207666PMC
October 2014

Abnormal XPD-induced nuclear receptor transactivation in DNA repair disorders: trichothiodystrophy and xeroderma pigmentosum.

Eur J Hum Genet 2013 Aug 12;21(8):831-7. Epub 2012 Dec 12.

DNA Repair Section, Dermatology Branch, Center for Cancer Research, National Cancer Institute/NIH, Bethesda, MD 20892, USA.

XPD (ERCC2) is a DNA helicase involved in nucleotide excision repair and in transcription as a structural bridge tying the transcription factor IIH (TFIIH) core with the cdk-activating kinase complex, which phosphorylates nuclear receptors. Mutations in XPD are associated with several different phenotypes, including trichothiodystrophy (TTD), with sulfur-deficient brittle hair, bone defects, and developmental abnormalities without skin cancer, xeroderma pigmentosum (XP), with pigmentary abnormalities and increased skin cancer, or XP/TTD with combined features, including skin cancer. We describe the varied clinical features and mutations in nine patients examined at the National Institutes of Health who were compound heterozygotes for XPD mutations but had different clinical phenotypes: four TTD, three XP, and two combined XP/TTD. We studied TFIIH-dependent transactivation by nuclear receptor for vitamin D (VDR) and thyroid in cells from these patients. The vitamin D stimulation ratio of CYP24 and osteopontin was associated with specific pairs of mutations (reduced in 5, elevated in 1) but not correlated with distinct clinical phenotypes. Thyroid receptor stimulation ratio for KLF9 was not significantly different from normal. XPD mutations frequently were associated with abnormal VDR stimulation in compound heterozygote patients with TTD, XP, or XP/TTD.
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http://dx.doi.org/10.1038/ejhg.2012.246DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3722669PMC
August 2013

XPD mutations in trichothiodystrophy hamper collagen VI expression and reveal a role of TFIIH in transcription derepression.

Hum Mol Genet 2013 Mar 5;22(6):1061-73. Epub 2012 Dec 5.

Istituto di Genetica Molecolare CNR, Pavia 27100, Italy.

Mutations in the XPD subunit of the transcription/DNA repair factor (TFIIH) give rise to trichothiodystrophy (TTD), a rare hereditary multisystem disorder with skin abnormalities. Here, we show that TTD primary dermal fibroblasts contain low amounts of collagen type VI alpha1 subunit (COL6A1), a fundamental component of soft connective tissues. We demonstrate that COL6A1 expression is downregulated by the sterol regulatory element-binding protein-1 (SREBP-1) whose removal from the promoter is a key step in COL6A1 transcription upregulation in response to cell confluence. We provide evidence for TFIIH being involved in transcription derepression, thus highlighting a new function of TFIIH in gene expression regulation. The lack of COL6A1 upregulation in TTD is caused by the inability of the mutated TFIIH complexes to remove SREBP-1 from COL6A1 promoter and to sustain the subsequent high rate of COL6A1 transcription. This defect might account for the pathologic features that TTD shares with hereditary disorders because of mutations in COL6A genes.
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http://dx.doi.org/10.1093/hmg/dds508DOI Listing
March 2013

TFIIH: when transcription met DNA repair.

Nat Rev Mol Cell Biol 2012 May 10;13(6):343-54. Epub 2012 May 10.

Institut de Génétique et de Biologie Moléculaire et Cellulaire, CNRS/INSERM/UdS, BP 163, 67404 Illkirch Cedex, C. U., Strasbourg, France.

The transcription initiation factor TFIIH is a remarkable protein complex that has a fundamental role in the transcription of protein-coding genes as well as during the DNA nucleotide excision repair pathway. The detailed understanding of how TFIIH functions to coordinate these two processes is also providing an explanation for the phenotypes observed in patients who bear mutations in some of the TFIIH subunits. In this way, studies of TFIIH have revealed tight molecular connections between transcription and DNA repair and have helped to define the concept of 'transcription diseases'.
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http://dx.doi.org/10.1038/nrm3350DOI Listing
May 2012

The phosphorylation of the androgen receptor by TFIIH directs the ubiquitin/proteasome process.

EMBO J 2011 Feb 14;30(3):468-79. Epub 2010 Dec 14.

Institut de Génétique et de Biologie Moléculaire et Cellulaire, Centre National de la Recherche Scientifique, INSERM, Université de Strasbourg, Illkirch cedex, France.

In response to hormonal stimuli, a cascade of hierarchical post-translational modifications of nuclear receptors are required for the correct expression of target genes. Here, we show that the transcription factor TFIIH, via its cdk7 kinase, phosphorylates the androgen receptor (AR) at position AR/S515. Strikingly, this phosphorylation is a key step for an accurate transactivation that includes the cyclic recruitment of the transcription machinery, the MDM2 E3 ligase, the subsequent ubiquitination of AR at the promoter of target genes and its degradation by the proteasome machinery. Impaired phosphorylation disrupts the transactivation, as observed in cells either overexpressing the non-phosphorylated AR/S515A, isolated from xeroderma pigmentosum patient (bearing a mutation in XPD subunit of TFIIH), or in which cdk7 kinase was silenced. Indeed, besides affecting the cyclic recruitment of the transcription machinery, the AR phosphorylation defect favourizes to the recruitment of the E3 ligase CHIP instead of MDM2, at the PSA promoter, that will further attract the proteasome machinery. These observations illustrate how the TFIIH phosphorylation might participate to the transactivation by regulating the nuclear receptors turnover.
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http://dx.doi.org/10.1038/emboj.2010.337DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3034013PMC
February 2011

Both XPD alleles contribute to the phenotype of compound heterozygote xeroderma pigmentosum patients.

J Exp Med 2009 Dec 23;206(13):3031-46. Epub 2009 Nov 23.

Institut de Génétique et de Biologie Moléculaire et Cellulaire, BP 10142, 67404 Illkirch Cedex, C.U. Strasbourg, France.

Mutations in the XPD subunit of the DNA repair/transcription factor TFIIH result in the rare recessive genetic disorder xeroderma pigmentosum (XP). Many XP patients are compound heterozygotes with a "causative" XPD point mutation R683W and different second mutant alleles, considered "null alleles." However, there is marked clinical heterogeneity (including presence or absence of skin cancers or neurological degeneration) in these XPD/R683W patients, thus suggesting a contribution of the second allele. Here, we report XP patients carrying XPD/R683W and a second XPD allele either XPD/Q452X, /I455del, or /199insPP. We performed a systematic study of the effect of these XPD mutations on several enzymatic functions of TFIIH and found that each mutation exhibited unique biochemical properties. Although all the mutations inhibited the nucleotide excision repair (NER) by disturbing the XPD helicase function, each of them disrupted specific molecular steps during transcription: XPD/Q452X hindered the transactivation process, XPD/I455del disturbed RNA polymerase II phosphorylation, and XPD/199insPP inhibited kinase activity of the cdk7 subunit of TFIIH. The broad range and severity of clinical features in XP patients arise from a broad set of deficiencies in NER and transcription that result from the combination of mutations found on both XPD alleles.
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http://dx.doi.org/10.1084/jem.20091892DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2806454PMC
December 2009

Neurological defects in trichothiodystrophy reveal a coactivator function of TFIIH.

Nat Neurosci 2007 Nov 21;10(11):1414-22. Epub 2007 Oct 21.

Institut de Génétique et de Biologie Moléculaire et Cellulaire, 1 rue Laurent Fries, BP 10142, 67404 Illkirch Cedex, C.U. Strasbourg, France.

Mutations in the XPD subunit of the DNA repair/transcription factor TFIIH yield the rare genetic disorder trichothiodystrophy (TTD). Although this syndrome was initially associated with a DNA repair defect, individuals with TTD develop neurological features, such as microcephaly and hypomyelination that could be connected to transcriptional defects. Here we show that an XPD mutation in TTD mice results in a spatial and selective deregulation of thyroid hormone target genes in the brain. Molecular analyses performed on the mice brain tissue demonstrate that TFIIH is required for the stabilization of thyroid hormone receptors (TR) to their DNA-responsive elements. The limiting amounts of TFIIH found in individuals with TTD thus contribute to the deregulation of TR-responsive genes. The discovery of an unexpected stabilizing function for TFIIH deepens our understanding of the pathogenesis and neurological manifestations observed in TTD individuals.
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http://dx.doi.org/10.1038/nn1990DOI Listing
November 2007

A combined approach identifies a limited number of new thyroid hormone target genes in post-natal mouse cerebellum.

J Mol Endocrinol 2007 Jul;39(1):17-28

Institut de Génomique Fonctionnelle de Lyon, Ecole Normale Supérieure de Lyon, Université de Lyon, UMR INRA CNRS 5242, IFR128 46 allée d'Italie, 69364 Lyon Cedex 07, France.

Thyroid hormones act directly on gene transcription in the post-natal developing cerebellum, controlling neuronal, and glial cell differentiation. We have combined three experimental approaches to identify the target genes that are underlying this phenomenon: 1) a microarray analysis of gene expression to identify hormone responsive genes in the cerebellum of Pax8-/- mice, a transgenic mouse model of congenital hypothyroidism; 2) a similar microarray analysis on primary culture of cerebellum neurons; and 3) a bioinformatics screen of conserved putative-binding sites in the mouse genome. This identifies surprisingly a small set of target genes, which, for some of them, might be key regulators of cerebellum development and neuronal differentiation.
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http://dx.doi.org/10.1677/JME-06-0054DOI Listing
July 2007

XPG stabilizes TFIIH, allowing transactivation of nuclear receptors: implications for Cockayne syndrome in XP-G/CS patients.

Mol Cell 2007 Apr;26(2):231-43

Laboratories for Organismal Biosystems, Graduate School of Frontier Biosciences, Osaka University, Osaka, Japan.

Mutations in the human XPG gene give rise to an inherited photosensitive disorder, xeroderma pigmentosum (XP) associated with Cockayne syndrome (XP-G/CS). The clinical features of CS in XP-G/CS patients are difficult to explain on the basis of a defect in nucleotide excision repair (NER). We found that XPG forms a stable complex with TFIIH, which is active in transcription and NER. Mutations in XPG found in XP-G/CS patient cells that prevent the association with TFIIH also resulted in the dissociation of CAK and XPD from the core TFIIH. As a consequence, the phosphorylation and transactivation of nuclear receptors were disturbed in XP-G/CS as well as xpg(-/-) MEF cells and could be restored by expression of wild-type XPG. These results provide an insight into the role of XPG in the stabilization of TFIIH and the regulation of gene expression and provide an explanation of some of the clinical features of XP-G/CS.
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http://dx.doi.org/10.1016/j.molcel.2007.03.013DOI Listing
April 2007

Dysregulation of the peroxisome proliferator-activated receptor target genes by XPD mutations.

Mol Cell Biol 2005 Jul;25(14):6065-76

Institut de Génétique et de Biologie Moléculaire et Cellulaire, Illkirch Cedex, CU Strasbourg, France.

Mutations in the XPD subunit of TFIIH give rise to human genetic disorders initially defined as DNA repair syndromes. Nevertheless, xeroderma pigmentosum (XP) group D (XP-D) patients develop clinical features such as hypoplasia of the adipose tissue, implying a putative transcriptional defect. Knowing that peroxisome proliferator-activated receptors (PPARs) are implicated in lipid metabolism, we investigated the expression of PPAR target genes in the adipose tissues and the livers of XPD-deficient mice and found that (i) some genes are abnormally overexpressed in a ligand-independent manner which parallels an increase in the recruitment of RNA polymerase (pol) II but not PPARs on their promoter and (ii) upon treatment with PPAR ligands, other genes are much less induced compared to the wild type, which is due to a lower recruitment of both PPARs and RNA pol II. The defect in transactivation by PPARs is likely attributable to their weaker phosphorylation by the cdk7 kinase of TFIIH. Having identified the phosphorylated residues in PPAR isotypes, we demonstrate how their transactivation defect in XPD-deficient cells can be circumvented by overexpression of either a wild-type XPD or a constitutively phosphorylated PPAR S/E. This work emphasizes that underphosphorylation of PPARs affects their transactivation and consequently the expression of PPAR target genes, thus contributing in part to the XP-D phenotype.
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http://dx.doi.org/10.1128/MCB.25.14.6065-6076.2005DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1168804PMC
July 2005

Nelfinavir induces necrosis of 3T3F44-2A adipocytes by oxidative stress.

J Acquir Immune Defic Syndr 2004 Dec;37(5):1556-62

INSERM 476 Unit, School of Medicine, Marseille, France.

Protease inhibitor treatment strongly diminishes mortality in HIV-infected patients. This treatment has also been associated with lipodystrophy and has been shown to alter adipocyte differentiation. The protease inhibitor nelfinavir has been indirectly implicated in the appearance and development of lipodystrophic syndrome, as well as in adipocyte cell death. The aim of this study was to evaluate the effects of nelfinavir on the 3T3-F442A adipocyte cell line. Nelfinavir (30 microM) induced cell death of 3T3-F442A adipocytes by a necrotic process that was not mediated by TNF-alpha. Treatment of cells with this protease inhibitor led to a significant increase in expression of the heme oxygenase-1 gene that could be reduced by 100 microM of the antioxidant ascorbate. Moreover, ascorbate had a protective effect on nelfinavir-induced necrosis, decreasing the percentage of necrotic cells by 70%. Our results show that nelfinavir induces necrosis of adipocytes mediated by a cellular increase of reactive oxygen species. This deleterious effect could be counterbalanced by ascorbate.
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http://dx.doi.org/10.1097/00126334-200412150-00003DOI Listing
December 2004

Selective regulation of vitamin D receptor-responsive genes by TFIIH.

Mol Cell 2004 Oct;16(2):187-97

Institut de Génétique et de Biologie Moléculaire et Cellulaire, BP 163, 67404 Illkirch Cedex, France.

Mutations in the XPD subunit of the transcription/repair factor TFIIH cause the Xeroderma pigmentosum disorder. We show that in some XP-D deficient cells, transactivation by the vitamin D receptor (VDR) is selectively inhibited for a subset of responsive genes, such as CYP24, and that the XPD/R683W mutation prevents VDR recruitment on its promoter. Contrary to other nuclear receptors, VDR, which lacks a functional A/B domain, is not phosphorylated and consequently not regulated by the cdk7 kinase of TFIIH. In fact, we demonstrate that the VDR transactivation defect resides in Ets1, another activator that cannot be phosphorylated by TFIIH in XP-D cells. Indeed, the phosphorylated Ets1 seems to promote the binding of VDR to its responsive element and trigger the subsequent recruitment of coactivators and RNA pol II. We propose a model in which TFIIH regulates the activity of nuclear receptors by phosphorylating either their A/B domain or an additional regulatory DNA binding partner.
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http://dx.doi.org/10.1016/j.molcel.2004.10.007DOI Listing
October 2004

Effects of antiretroviral drug combinations on the differentiation of adipocytes.

AIDS 2002 Jan;16(1):13-20

INSERM Unit 476, School of Medicine of Marseilles, Marseilles, France.

Objective: Preadipocyte cell lines present a cell model with which to understand the physiopathological mechanisms underlying lipodystrophy syndrome, a common complication observed in patients treated with highly active antiretroviral therapy (HAART) that, in general, is associated with the use of protease inhibitors (PI) and nucleoside reverse transcriptase inhibitors (NRTI). The aim of this study was to evaluate the effects of NRTI and of PI and NRTI combinations in this cell model.

Methods: The differentiation of 3T3-F442A cells was studied by monitoring the expression of specific genes in the presence of therapeutic concentrations of antiretroviral drugs. Messenger RNA (mRNA) was quantified by two reverse transcription-PCR-based methods.

Results: In the presence of 2 microM saquinavir, 30 microM ritonavir or 1 microM zidovudine preadipocytes delayed their differentiation, whereas the use of 10 microM nelfinavir led to cell death. Indinavir (10 microM) promoted lipoprotein lipase expression whereas 1 microM lamivudine or 1 microM stavudine enhanced slightly the expression of the malic enzyme gene. However, the combination of indinavir, lamivudine and stavudine led to a large increase in both lipoprotein lipase and malic enzyme mRNA transcription whereas the combination of indinavir, lamivudine and zidovudine led to a 2.5-fold increase in the expression of the lipogenic malic enzyme gene. Similar potentiating effects of NRTI and PI were observed on the expression of the fatty acid synthase gene.

Conclusions: Our data suggest that, like PI (although to a lesser extent) NRTI interfere with the differentiation process of adipocytes. In addition, we demonstrate that the effects produced by combinations of NRTI and PI are different from those elicited by each drug separately. This point may be particularly relevant in understanding the physiopathological mechanisms underlying the lipodystrophic syndrome.
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http://dx.doi.org/10.1097/00002030-200201040-00003DOI Listing
January 2002
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