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The Department of Biomedicine

BBB Seminar: Piergiorgio Percipalle

Actin and actin-associated proteins in transcriptional and post-transcriptional control of gene expression

Piergiorgio Percipalle,
Department of Cell and Molecular Biology, Karolinska Institutet, Stockholm, Sweden

Actin participates in several essential processes in the cell nucleus. Actin constitutes part of chromatin remodelling complexes, it is associated with the transcription machinery, it becomes incorporated into newly synthesized ribonucleoproteins and it influences long-range chromatin organization. As in the cytoplasm, nuclear actin works in conjunction with different types of actin-binding proteins that regulate its function and bridge interactions between actin and other nuclear components.

In the first part of the lecture I will present evidence that specific actin-heterogeneous ribonucleoprotein (hnRNP) interactions are required for the establishment of permissive chromatin for pre-mRNA elongation and that there is a requirement for controlled actin polymerization.

At the post-transcriptional level, the role of the actin-associated hnRNP CBF-A in mRNA trafficking will be discussed. We recently discovered a conserved function of CBF-A as a transacting factor for mRNA transport and localized translation in oligodendrocytes and neurons. We currently work on the hypothesis that co-transcriptional recognition of cis-acting elements located within nascent mRNA transcripts is needed to configure transport-competent RNPs.

In the last part of the lecture focus will be placed on the synergy between actin and nuclear myosin 1 in rRNA biogenesis.

 

Host: Clive Bramham, Department of Biomedicine