Hippocampal pyramidal cells in adult Fmr1 knockout mice exhibit an immature-appearing profile of dendritic spines.
Fragile X syndrome (FXS) is a common form of mental retardation caused by the absence of functional fragile X mental retardation protein (FMRP). FXS is associated with elevated density and length of dendritic spines, as well as an immature-appearing distribution profile of spine morphologies in the neocortex. Mice that lack FMRP (Fmr1 knockout mice) exhibit a similar phenotype in the neocortex, suggesting that FMRP is important for dendritic spine maturation and pruning. Examination of Golgi-stained pyramidal cells in hippocampal subfield CA1 of adult Fmr1 knockout mice reveals longer spines than controls and a morphology profile that, while essentially opposite of that described in the Fmr1 knockout neocortex, appears similarly immature. This finding strongly suggests that FMRP is required for the processes of spine maturation and pruning in multiple brain regions and that the specific pathology depends on the cellular context.
Grossman
Aaron W
AW
Beckman Institute, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA.
Elisseou
Nicholas M
NM
McKinney
Brandon C
BC
Greenough
William T
WT
D000818:Animals; D016009:Chi-Square Distribution; D049229:Dendritic Spines / Q000145:classification / Q000502:physiology* / Q000648:ultrastructure; D051860:Fragile X Messenger Ribonucleoprotein 1 / Q000235:genetics*; D006624:Hippocampus / Q000166:cytology*; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D017966:Pyramidal Cells / Q000502:physiology / Q000648:ultrastructure*; D016622:Silver Staining / Q000379:methods; D014793:Visual Cortex / Q000648:ultrastructure
D051860:Fragile X Messenger Ribonucleoprotein 1; C497684:Fmr1 protein, mouse