Fragile X mental retardation protein replacement restores hippocampal synaptic function in a mouse model of fragile X syndrome.
Fragile X syndrome (FXS) is caused by a mutation that silences the fragile X mental retardation gene (FMR1), which encodes the fragile X mental retardation protein (FMRP). To determine whether FMRP replacement can rescue phenotypic deficits in a fmr1-knockout (KO) mouse model of FXS, we constructed an adeno-associated virus-based viral vector that expresses the major central nervous system (CNS) isoform of FMRP. Using this vector, we tested whether FMRP replacement could rescue the fmr1-KO phenotype of enhanced long-term depression (LTD), a form of synaptic plasticity that may be linked to cognitive impairments associated with FXS. Extracellular excitatory postsynaptic field potentials were recorded from CA3-CA1 synaptic contacts in hippocampal slices from wild-type (WT) and fmr1-KO mice in the presence of AP-5 and anisomycin. Paired-pulse low-frequency stimulation (PP-LFS)-induced LTD is enhanced in slices obtained from fmr1 KO compared with WT mice. Analyses of hippocampal synaptic function in fmr1-KO mice that received hippocampal injections of vector showed that the PP-LFS-induced LTD was restored to WT levels. These results indicate that expression of the major CNS isoform of FMRP alone is sufficient to rescue this phenotype and suggest that post-developmental protein replacement may have the potential to improve cognitive function in FXS.
Zeier
Z
Z
Department of Molecular Genetics and Microbiology, University of Florida College of Medicine, Gainesville, FL 32610-0266, USA.
Kumar
A
A
Bodhinathan
K
K
Feller
J A
JA
Foster
T C
TC
Bloom
D C
DC
D000818:Animals; D000229:Dependovirus / Q000235:genetics; D004195:Disease Models, Animal; D004558:Electric Stimulation / Q000379:methods; D019706:Excitatory Postsynaptic Potentials / Q000235:genetics / Q000502:physiology; D051860:Fragile X Messenger Ribonucleoprotein 1 / Q000235:genetics* / Q000378:metabolism; D005600:Fragile X Syndrome / Q000235:genetics / Q000378:metabolism / Q000628:therapy*; D015870:Gene Expression; D015316:Genetic Therapy / Q000379:methods*; D005822:Genetic Vectors; D006624:Hippocampus / Q000503:physiopathology*; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D012333:RNA, Messenger / Q000235:genetics; D013569:Synapses / Q000502:physiology*
D051860:Fragile X Messenger Ribonucleoprotein 1; D012333:RNA, Messenger; C497684:Fmr1 protein, mouse