Dataset Information

De Novo Proteome in Fragile X Syndrome

ABSTRACT: Elevated translation has been reported in multiple models of fragile X syndrome (FXS) and in FXS individuals, however, whether it is limited to fragile X mental retardation protein (FMRP) target mRNAs or neuronal activity-derived conditions remains unclear. We examined this question by measuring the de novo proteome of the Fmr1 knockout (KO) mouse hippocampus compared to normal littermates in steady-state and mGluR-stimulated conditions. Our results reveal that the altered de novo translational profile in KO mice involves similar numbers of upregulated and downregulated proteins in both conditions and that mGluR-dependent translation in KOs is variable and inconsistent compared to normal. Nascent proteins from the steady-state translation and activity-dependent translation groups had little overlap and the mRNAs of the candidate proteins did not possess any unifying motifs or properties. Validation of the highest interest FXS candidates revealed differences in de novo synthesis and final abundance levels, which correlated with changes in synaptic levels of miRNA. Taken together, these data suggest that translation is stimulus-specific and not generalized, and that there is more complex, multi-tiered regulation of protein expression that is disrupted in FXS than previously described. To establish relevance of these data to human patients and future biomarker efforts, three candidates were examined in FXS patient plasma and two exhibited altered expression. One was rescued in KO mice blood following a treatment shown previously to ameliorate phenotypes in FXS model mice. In summary, our results provide a clear distinction between steady-state and activity-dependent de novo proteomic profiles in FXS model mice, providing a database of proteins that are synthesized incorrectly, and describe a novel approach for developing biomarkers for FXS.

INSTRUMENT(S): Q Exactive

ORGANISM(S): Mus <mouse, Genus> (ncbitaxon:10088)

SUBMITTER: Dr. Thomas A. Neubert