A role for eIF4E on mRNA turnover in processing bodies

FERRERO PV; LAYANA C.; RIVERA POMAR R

Tucuman

Congreso; XLV Reunión Anual - Sociedad Argentina de Investigación en Bioquímica y Biología Molecular; 2009

SAIB

New functions for the eukaryotic translation initiation factor eIF4Ehave been recently described in mRNA metabolism, namelynuclear export and ribonucleoprotein complex (RNP) remodelling.RNPs remodelling occurs when mRNAs are translocated fromactive polysomes to cytoplasmic processing bodies (PBs). Toelucidate the pathway of RNP remodelling involving eIF4E wehave studied the functional consequences of the interactionbetween eIF4E, mRNAs and PBs components in vivo. Drosophilamelanogaster eIF4E isoform 1 is present in PBs. We havegenerated eIF4E mutants on key tryptophan (W) residues byreplacing them with alanine (A). W100 and W147 are required formRNA 5´cap binding, and W117 is required for protein-proteininteractions. We transfected Drosophila S2 cells with wild type andmutant eIF4E-1 of variants to evaluate the requirement for PBslocalization. Only the mutation of W117 produced relocalization ofeIF4E. Similar results were obtained by mutation of the equivalentW in the mouse eIF4E. Therefore, protein-protein interactionsrather than cap binding are required for PBs localization. Todetermine whether eIF4E-interaction is required for PBs assemblywe mutated the eIF4E-binding sites of 4ET-Like and me31b, bothpresent in PBs. We will present a model for the remodellingpathway.