Publication Type:Journal Article
Source:PLoS One, Volume 7, Issue 6, p.e39338 (2012)
Keywords:Amino Acid Motifs, Animals, Antibodies, Monoclonal, Base Sequence, Brain, Calcium-Calmodulin-Dependent Protein Kinase Type 2, Cell Cycle Proteins, DNA Primers, Fragile X Mental Retardation Protein, HeLa Cells, Humans, Immunoprecipitation, Mice, Mice, Inbred C57BL, Mice, Knockout, Microtubule-Associated Proteins, Molecular Sequence Data, Neurons, NIH 3T3 Cells, Polyribosomes, Protein Binding, Protein Biosynthesis, Ribonucleoproteins, RNA-Binding Proteins
Fragile X syndrome is caused by the absence of the Fragile X Mental Retardation Protein (FMRP), an RNA-binding protein. FMRP is associated with messenger RiboNucleoParticles (mRNPs) present in polyribosomes and its absence in neurons leads to alteration in synaptic plasticity as a result of translation regulation defects. The molecular mechanisms by which FMRP plays a role in translation regulation remain elusive. Using immunoprecipitation approaches with monoclonal Ab7G1-1 and a new generation of chicken antibodies, we identified Caprin1 as a novel FMRP-cellular partner. In vivo and in vitro evidence show that Caprin1 interacts with FMRP at the level of the translation machinery as well as in trafficking neuronal granules. As an RNA-binding protein, Caprin1 has in common with FMRP at least two RNA targets that have been identified as CaMKIIα and Map1b mRNAs. In view of the new concept that FMRP species bind to RNA regardless of known structural motifs, we propose that protein interactors might modulate FMRP functions.