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Research groups

Cell biology and Biotechnology

Dr Rafael Rodríguez Daga. UPO
Control of cellular space and morphogenesis
Dr Rafael Rodríguez Daga. UPO
Principal Investigator

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Summary

NUCLEAR ARCHITECTURE AND DYNAMICS
RAFAEL R. DAGA

One of the current challenges of cell biology in the postgenomic era is to understand how the DNA is organized in the 3D nuclear space and how this organization contributes to essential cellular processes such as gene expression, DNA repair or chromosome segregation. Changes in nuclear architecture correlates with developmental and differentiation processes and defects in architectural elements are responsible for several human diseases.
  
       Our lab uses the fission yeast Schizosaccharomyces pombe as eukaryotic model organism. In this yeast, chromosomes are anchored to the nuclear envelope via specific DNA loci such as centromeres, telomeres and TFIIIC binding sites. This remarkable topological organization requires the presence of distinct DNA sequences and chromatin domains and relies on a large number of proteins that mediate chromatin interactions with the nuclear envelope. Therefore, the nuclear envelope serves as a dynamic scaffold to anchor and organize distinct chromosomal domains, thus generating a higher-order nuclear architecture. 

Fission yeast nuclear organisation shares many features with that of more complex nuclei of higher eukaryotes. These features include large repeat-rich centromeres and peripherally localised heterochromatin relying on RNAi-dependent pathway. This, in combination with a small 13.8 Mb genome, just three chromosomes and a relatively large nucleus (2.5-3 µm in diameter), suitable for microscopic observation, makes fission yeast a convenient tool for understanding conserved principles underlying eukaryotic nuclear organisation and function. Both fission yeast and metazoans possess evolutionarily conserved physical links between the DNA and the nuclear envelope that contribute to creating and maintaining nuclear architecture. Such links are prominent at centromeric and telomeric heterochromatin but are also found at a large number of other sites within the fission yeast genome.

Our lab uses a combination of yeast genetics, molecular biology, live cell microscopy and physical manipulation of the nucleus to study mechanisms regulating the spatial organization of the fission yeast nucleus and genome, and the implications behind this organization in chromosome segregation.

THE ROLE OF TPR NUCLEOPORINS IN NUCLEAR ORGANIZATION
I. ASOCIADO: SILVIA SALAS PINO

In recent years, the function of the nuclear envelop (NE) and nuclear pore complex (NPC) have been extended from the regulation of nucleocytoplasmic traffic to an increasing number of nuclear functions, such as the anchoring of regulatory factors and the compartmentalization of chromatin, which in turn contributes to genome regulation and maintenance. The nuclear periphery is not homogeneous, but rather harbours different DNA and protein domains, generating architectural nuclear microenvironments, associated to gene silencing and activation. Importantly, specialized NE microenvironments occur from single-celled to multicellular and more complex organisms. 

TPR nucleoporins (Translocated Promoter Region) are evolutionally conserved multifunctional coiled-coil proteins that localize at the nucleoplasmic side of the NPC forming the structure called nuclear basket. TPR nucleoporins have been shown to regulate different nuclear processes and cell cycle dependent spatio-temporal signalling, including recruitment to the NE during interphase, of components of the spindle assembly checkpoint (SAC), regulation of nuclear SUMO homeostasis or mRNA export and quality control. 

The fission yeast nucleus undergoes closed mitosis, in which an intranuclear spindle segregates chromosomes while the NE remains assembled. At the beginning of mitosis however, many elements of the nuclear architecture disassemble, to re-assemble later in the daughter cells. This allows the study of the dynamics of cell cycle-dependent regulation of nuclear organization

My main interest is to gain insight in how the NPC and TPR proteins influence nuclear organization and how this organization is dynamically rearranged during the cell cycle.