mRNA Formation and Function

Responsable de Grupo: Carles Mª Suñé Negre

Instituto de Parasitología y Biomedicina “López Neyra”

Parque Tecnológico de Ciencias de la Salud

Avenida del Conocimiento s/n

Armilla 18100 Granada

Teléfono: 958 181645 Fax: 958 181632

Componentes del grupo:

Carles Mª Suñé Negre, Científico Titular, e.mail: csune (añada @ipb.csic.es)

Inmaculada Montanuy Sellart, Becaria predoctoral, e.mail: imontanuy (añada @ipb.csic.es)

Marta Gutiérrez Guisado, Becaria predoctoral, e.mail: mgutiguis (añada @hotmail.com)

Miguel Sánchez Álvarez, Becario predoctoral, e.mail: msalvare (añada @ipb.csic.es)

Actividad Científica

Líneas de Investigación:

Expression of protein-coding genes is a multi-step process beginning with transcription by RNA polymerase II (RNAPII) in the nucleus. During transcription, the nascent pre-mRNA undergoes several processing steps including capping, splicing, and polyadenylation. The mature mRNA is then exported to the cytoplasm for translation. A distinct cellular machine carries out each of the steps in gene expression, but growing evidence indicates that there is an extensive network of coupled interactions between each machine. Although the existence of these connections is widely accepted, their nature remains to be elucidated. Our laboratory is interested in understanding how the connections between the mRNA transcription elongation and processing machineries take place. Part of the laboratory is studying a protein, the transcription elongation factor CA150 (also known as TCERG1, for transcription elongation regulator 1, HUGO Gene Nomenclature Committee), which may be involved in the coupling of those processes. The other part broadens the scope of the laboratory project by studying the molecular mechanisms of transcription elongation by RNAPII.

Connections between CA150 and the splicing machineryWe continue to investigate the nature of the interactions of CA150 with the splicing machinery. We are currently involved in a project aimed to study the spatial relationship between CA150 and active sites of transcription in the cell. We are also working in the identification and characterization of new CA150-binding proteins, which may provide insights into the mechanism of CA150 function.Molecular analysis of RNAPII complexesThe transcriptional regulation of HIV-1 is unique in many aspects; however, there are cellular genes that may follow a similar regulation. In particular, it has been shown that a block to elongation is largely responsible for decreased transcription of c-myc. This block to c-myc elongation in mammalian cells is probably due to paused polymerase complexes in the promoter proximal region, rather than to premature termination, which resembles the situation observed in the transcription of HIV-1 genes. We have started a project aimed to elucidate the molecular mechanisms of transcription elongation by RNAPII. Our project hypothesizes that distinct promoter elements direct the assembly of RNAPII complexes that differ in their elongation efficiency, thus controlling the expression of genes at the elongation phase of transcription. The work utilizes molecular, biochemical and immunological approaches regarding the composition and regulation of RNAPII pre-initiation and elongation complexes assembled on the HIV-1 and c-myc promoters.

Publicaciones más relevantes:

- Suñé, C., T. Hayashi, Y. Liu, W.S. Lane, R.A. Young, and M.A. Garcia-Blanco. 1997. CA150, a nuclear protein associated with the RNA polymerase II holoenzyme, is involved in Tat-activated HIV-1 transcription. Mol. Cell. Biol. 17, 6029-6039.

- Liu, Y., Suñé, C., and M.A. Garcia-Blanco. 1999. HIV-1 Tat-dependent activation of an arresred RNA polymerase II elongation complex. Virology 255, 337-346.

- Suñé, C., and M.A. Garcia-Blanco. 1999. Transcriptional cofactor CA150 regulates RNA polymerase II elongation in a TATA-box dependent manner. Mol. Cell. Biol. 19, 4719-4728.

- Carty, S.M., A.C. Goldstrohm, C. Suñé, M.A. Garcia-Blanco, and A.L. Greenleaf. 2000. Protein-interaction modules that organize nuclear function: FF domains of CA150 bind the phosphoCTD of RNA polymerase II. Proc. Natl. Acad. Sci. USA. 97, 9015-9020.

- Bohne, J., S.E. Cole, C. Suñé, B.R. Lindman, V.D. Ko, T.F. Vogt, and M.A. Garcia-Blanco. 2000. Expression analysis and mapping of the mouse and human transcriptional regulator CA150. Mamm. Genome 11, 930-933.

- Suñé, C., A.C. Goldstrohm, J. Peng, D.H. Price and M.A. Garcia-Blanco. 2000. An in vitro system that recapitulates EIAV Tat-mediated inhibition of HIV-1 Tat activity demonstrates a role for P-TEFb and associated proteins in the mechanism of Tat activation. Virology. 274, 356-366.

- Goldstrohm, A.C., T.R. Albrecht, C. Suñé, M. Bedford, and M.A. Garcia-Blanco. 2001. The transcription elongation factor CA150 interacts with RNA polymerase II and the pre-mRNA splicing factor SF1 to repress transcription Mol. Cell. Biol. 21, 7617-7628.

- Brennan, L.E., C. Suñé, and T. Klimkait. 2002. A neutravidin-based assay for reverse transcriptase-suitable for high throughput screening of HIV activity. J. Biochem and Mol. Biol. 35, 262-266.

- Suñé, C.,L.E. Brennan, D.R. Stover, and T. Klimkait. 2004. Effect of polymorphisms on the replicative capacity of protease inhibitor-resistant HIV-1 variants under drug pressure. Clin. Microbiol. Infect. 10, 119-126.

- Holguin, A., C. Suñé, F. Hamy, V. Soriano, and T. Klimkait. 2006. Natural polymorphisms in the protease gene modulate the replicative capacity of non-B HIV-1 variants in the absence of drug pressure. J. Clin. Virol. 36, 264-271.

- Sánchez-Álvarez, M., A.C. Goldstrohm, M.A. Garcia-Blanco, and, C. Suñé. 2006. The human transcription elongation factor CA150 localizes to splicing factor-rich nuclear speckles and assembles transcription and splicing components into complexes through its amino and carboxyl regions. Mol. Cel. Biol. 26, 4998-5014.