Transcription

Thomas Oelgeschläger PhD - Group Leader

Valentina Capùto, PhD
Samuel Fatoba, BSc
Lukasz Jasnos, PhD
 

For more information please visit our laboratory website

The characteristics of living cells are determined by their composite proteins, which result from expression of protein coding genes. In multi-cellular organisms different cell types harbour identical genomes and cell specialization is achieved through tightly controlled and co-ordinated expression of a cell type-specific subset of genes. Aberrant gene expression is a major cause for disease, including various forms of cancer.

The first step of gene expression, and the predominant step at which gene expression is regulated, is the transfer of genetic information from DNA to RNA by the biochemical process of transcription: the synthesis of RNA on a DNA template by RNA polymerases. Eukaryotic cells contain three different RNA polymerases and synthesis of mRNA at protein-coding class II genes is catalyzed by RNA polymerase II (RNAP II). This laboratory investigates the molecular mechanisms involved in the regulated transcription of protein-coding genes by RNAP II in human cells.

Transcription of protein-coding genes in eukaryotes is a complicated process that requires a large number of different protein factors in addition to RNAP II. In order to initiate RNA synthesis, RNAP II must assemble minimally with six so-called general transcription factors (GTFs): designated TFIIA, TFIIB, TFIID, TFIIE, and TFIIH, at the promoter DNA region encompassing the transcription start site to form a preinitiation complex (PIC). The PIC is of remarkable size and complexity; it contains well over 40 polypeptides and has a molecular mass exceeding 2MDa.

Regulation of RNA polymerase II transcription is generally mediated by proteins that bind to gene-specific regulatory DNA sequences and that either stimulate (activators) or inhibit (repressors) transcription at various steps of the transcription initiation pathway.

The function of transcription activators and repressors requires, in addition to the general RNAP II transcription machinery, a complex array of positive-and negative acting co-factors. A major research objective is to understand at the molecular level the functional interplay of gene- and cell type-specific DNA-binding transcription regulators, (gene-specific) co-factor activities, and the general RNAP II transcription machinery. Our main experimental approach involves the reconstitution of human cell-free systems that can accurately transcribe cloned genes in the test tube and that are responsive to physiologically relevant transcription regulators. These systems are biochemically dissected to identify the functionally relevant polypeptides and to study their mechanism of action. Biochemical studies are complemented by detailed studies in living human cells.

Selected references:

Deng, W., Malecová, B., Oelgeschläger, T. and Roberts, S.G.E. (2009)
TFIIB recognition elements control the TFIIA-NC2 axis in transcriptional regulation.
Mol. Cell. Biol., 29: 1389-1400.

Gross, P. and Oelgeschläger, T. (2006)
Core promoter-selective RNA polymerase II transcription.
Biochem. Soc. Symp., 73: 225-236.

Boyer-Guittaut, M., Birsoy, K., Potel, C., Elliott, G., Jaffray, E., Desterro, J.M., Hay, R.T. and Oelgeschlager, T. (2005)
SUMO-1 modification of human TFIID complex subunits: Inhibition of TFIID promoter binding activity through SUMO-1 modification of hsTAF5.
J. Biol. Chem., 280: 9937-9945.

Oelgeschläger, T. (2002)
Regulation of RNA polymerase II activity by CTD phosphorylation and cell cycle control.
J.Cell. Physiol. 190: 160-169. Review.

Christova, R. and Oelgeschläger, T. (2002)
Association of human TFIID-promoter complexes with silenced mitotic chromatin in vivo.
Nature Cell Biol. 4: 79-82.

Castano, E., Gross, P., Wang, Z., Roeder, R.G. and Oelgeschläger, T. (2000)
The C-terminal domain-phosphorylated IIO form of RNA polymerase II is associated with the transcription repressor NC2 (Dr1/DRAP1) and is required for transcription activation in human nuclear extracts.
Proc. Natl. Acad. Sci. (USA) 97: 7184-7189.

Knutson, A., Castano, E., Oelgeschläger, T., Roeder, R.G. and Westin, G. (2000)
Downstream promoter sequences facilitate the formation of a specific transcription factor IIDpromoter complex topology required for efficient transcription from the megalin/low density lipoprotein receptor-related protein 2 promoter.
J. Biol. Chem., 275: 14190-14197.