RT Journal Article
SR Electronic
T1 Postadolescent Changes in Regional Cerebral Protein Synthesis: An In Vivo Study in the Fmr1 Null Mouse
JF The Journal of Neuroscience
JO J. Neurosci.
FD Society for Neuroscience
SP 5087
OP 5095
DO 10.1523/JNEUROSCI.0093-05.2005
VO 25
IS 20
A1 Mei Qin
A1 Julia Kang
A1 Thomas V. Burlin
A1 Chunhui Jiang
A1 Carolyn Beebe Smith
YR 2005
UL http://www.jneurosci.org/content/25/20/5087.abstract
AB Methylation-induced transcriptional silencing of the fragile X mental retardation-1 (Fmr1) gene leads to absence of the gene product, fragile X mental retardation protein (FMRP), and consequently fragile X syndrome (FrX), an X-linked inherited form of mental retardation. Absence of FMRP in Fmr1 null mice imparts some characteristics of the FrX phenotype, but the precise role of FMRP in neuronal function remains unknown. FMRP is an RNA-binding protein that has been shown to suppress translation of certain mRNAs in vitro. We applied the quantitative autoradiographic l-[1-14C]leucine method to the in vivo determination of regional rates of cerebral protein synthesis (rCPS) in adult wild-type (WT) and Fmr1 null mice at 4 and 6 months of age. Our results show a substantial decrease in rCPS in all brain regions examined between the ages of 4 and 6 months in both WT and Fmr1 null mice. Superimposed on the age-dependent decline in rCPS, we demonstrate a regionally selective elevation in rCPS in Fmr1 null mice. Our results suggest that the process of synaptic pruning during young adulthood may be reflected in decreased rCPS. Our findings support the hypothesis that FMRP is a suppressor of translation in brain in vivo.