Characterization of messenger ribonucleoproteincomplexes (mRNPs) during cellular stresses

• Applicant: Professorin Dr. Heike Krebber
• Subject Area: Cell Biology
• Term: from 2008 to 2015
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 82532115

Exposure of cells to various forms of environmental stresses, like thermal or chemical changes, lead to a reduced gene expression of regular genes and the favored expression of stress proteins (heat shock proteins). Our recent results have uncovered that the Saccharomyces cerevisiae mRNA binding protein and mRNA export factor Npl3p dissociates from the mRNA during stress and leaves it exportincompetent behind. It is currently unknown how this dissociation is initiated. We would like to identify the signal-cascade that is responsible for this effect and investigate if Npl3p protein modifications might lead to the dissociation or if rather protein protein interactions are the trigger for the rearrangement of the mRNA/protein complexes. Our recent results have identified Gbp2p and Hrb1p as Npl3p-homologoues mRNA binding and shuttling proteins. We will analyze their behavior during cellular stress and compare it to that of Npl3p. Our unpublished results have revealed already differences. While the expression level of both, Npl3p and Gbp2p remain constant during stress, Hrb1p-expression is significantly increased, indicating an augmented requirement for this RNA-binding protein. Since Npl3p is not involved in the export of the heat shock mRNAs as we have shown earlier, we will address, which mRNA export factors mediate that process. Finally, we aim to find those RNA-sequences within the heat shock mRNAs that are responsible for their selective export.

• DFG Programme: Research Grants