Cellular and subcellular distribution of spinophilin, a PP1 regulatory protein that bundles F-actin in dendritic spines.
Spinophilin is an actin binding protein that positions protein phosphatase 1 next to its substrates in dendritic spines. It contains a single PDZ domain and has the biochemical characteristics of a cytoskeletal scaffolding protein. Previous studies suggest that spinophilin is present in most spines, but the concentration of spinophilin varies from brain region to region in a manner that does not simply reflect differences in spine density. Here, we show that spinophilin is enriched in the great majority of dendritic spines in cerebral cortex, caudatoputamen, hippocampal formation, and cerebellum, irrespective of regional differences in spinophilin concentration. In addition, spinophilin is present postsynaptic to asymmetrical contacts on interneuronal dendritic shafts. We further show that, in hippocampus and ventral pallidum, spinophilin is occasionally present in dendritic shafts adjacent to gamma-aminobutyric acid-containing contacts. Thus, the functional role of spinophilin may not be exclusively restricted to excitatory synapses and may be significant at a small fraction of inhibitory contacts. These data also suggest that the concentration of spinophilin per spine is variable and is likely regulated by local physiological factors and/or regional influences.
Ouimet
Charles C
CC
Department of Biomedical Sciences, College of Medicine, Florida State University, Tallahassee, Florida 32303, USA. charles.ouimet@med.fsu.edu
Katona
István
I
Allen
Patrick
P
Freund
Tamás F
TF
Greengard
Paul
P
D000199:Actins / Q000378:metabolism*; D000818:Animals; D001479:Basal Ganglia / Q000378:metabolism / Q000648:ultrastructure; D001921:Brain / Q000378:metabolism* / Q000648:ultrastructure; D049229:Dendritic Spines / Q000378:metabolism* / Q000648:ultrastructure; D006624:Hippocampus / Q000378:metabolism / Q000648:ultrastructure; D007150:Immunohistochemistry; D007395:Interneurons / Q000378:metabolism / Q000648:ultrastructure; D008297:Male; D008840:Microfilament Proteins / Q000378:metabolism*; D018613:Microscopy, Confocal; D046529:Microscopy, Electron, Transmission; D009419:Nerve Tissue Proteins / Q000378:metabolism*; D009433:Neural Inhibition / Q000502:physiology; D010749:Phosphoprotein Phosphatases / Q000378:metabolism*; D054645:Protein Phosphatase 1; D051381:Rats; D017207:Rats, Sprague-Dawley; D013569:Synapses / Q000378:metabolism / Q000648:ultrastructure; D013570:Synaptic Membranes / Q000378:metabolism / Q000648:ultrastructure; D009435:Synaptic Transmission / Q000502:physiology; D005680:gamma-Aminobutyric Acid / Q000378:metabolism; D000099273:Neurabins
D000199:Actins; D008840:Microfilament Proteins; D009419:Nerve Tissue Proteins; D010749:Phosphoprotein Phosphatases; D054645:Protein Phosphatase 1; D005680:gamma-Aminobutyric Acid; D000099273:Neurabins