Pumilio2-mediated control of local protein expression in neurons

• Applicant: Professor Dr. Michael Kiebler
• Subject Area: General Genetics and Functional Genome Biology ; Biochemistry ; Cell Biology
• Term: from 2015 to 2019
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 270067186

Regulation of local protein synthesis at the synapse is particularly important in primary neurons. Here, a set of specific mRNAs is packaged with the help of RNA-binding proteins (RBPs) into ribonucleoprotein particles (RNPs or RNA granules) and transported along microtubules into dendrites near synapses. It is widely believed that translation is repressed during transport. However, the underlying mechanisms and molecules involved in translational regulation remain poorly understood. The neuron-specific RBP Pumilio2 (Pum2) is a well-known, conserved translational regulator in many organisms and cell types. Here, Pum2 has been implicated in the translational regulation of eIF4E mRNA as well as mRNAs coding for several sodium channels such as Nav1.1 and Nav1.6. Pum2-deficient primary hippocampal neurons display deficits in dendritic spine morphogenesis as well as in the excitability of neurons. It is important to note that Pum2 knock-down in mice causes epileptic seizures. Pum2 is a component of Staufen2 (Stau2)-containing RNPs, with Stau2 being another well-known RBP involved in dendritic mRNA localization. Therefore, it is tempting to speculate that Pum2 is involved in the control of local expression of localized transcripts in neurons. To gain systematic insight into the role of Pum2 in this process, we plan to combine RNA granule isolation from mouse brain with polysome gradient fractionation of wild type and Pum2-deficient mouse brains to identify physiologically relevant Pum2 target mRNAs. In a collaborative approach with Medenbach (Project 9), we will establish an in vitro translation system from mouse neuronal tissue to recapitulate regulation. The combination with sophisticated mouse models in the Kiebler lab will then allow us to elucidate the underlying mechanisms of Pum2 mediated control of protein synthesis with a special emphasis on local translation at mature synapses and to gain molecular insight into how misregulation results in disease.

• DFG Programme: Research Units
• Subproject of: FOR 2333: Macromolecular Complexes in mRNA translocation