FRET-FLIM investigation of PSD95-NMDA receptor interaction in dendritic spines; control by calpain, CaMKII and Src family kinase.
Little is known about the changes in protein interactions inside synapses during synaptic remodeling, as their live monitoring in spines has been limited. We used a FRET-FLIM approach in developing cultured rat hippocampal neurons expressing fluorescently tagged NMDA receptor (NMDAR) and PSD95, two essential proteins in synaptic plasticity, to examine the regulation of their interaction. NMDAR stimulation caused a transient decrease in FRET between the NMDAR and PSD95 in spines of young and mature neurons. The activity of both CaMKII and calpain were essential for this effect in both developmental stages. Meanwhile, inhibition of Src family kinase (SFK) had opposing impacts on this decrease in FRET in young versus mature neurons. Our data suggest concerted roles for CaMKII, SFK and calpain activity in regulating activity-dependent separation of PSD95 from GluN2A or GluN2B. Finally, we found that calpain inhibition reduced spine growth that was caused by NMDAR activity, supporting the hypothesis that PSD95-NMDAR separation is implicated in synaptic remodeling.
Institut Universitaire en Santé Mentale de Québec, Université Laval, Québec, QC, Canada.
Kim
K
Doré
Institut Universitaire en Santé Mentale de Québec, Université Laval, Québec, QC, Canada.
Simon
S
Labrecque
Institut Universitaire en Santé Mentale de Québec, Université Laval, Québec, QC, Canada.
Christian
C
Tardif
Institut Universitaire en Santé Mentale de Québec, Université Laval, Québec, QC, Canada; Département de Biochimie, Microbiologie et Bio-informatique, Université Laval, Québec, QC, Canada.
Paul
P
De Koninck
D000818:Animals; D054732:Calcium-Calmodulin-Dependent Protein Kinase Type 2 / Q000502:physiology*; D002154:Calpain / Q000502:physiology*; D002478:Cells, Cultured; D049229:Dendritic Spines / Q000201:enzymology / Q000378:metabolism* / Q000502:physiology; D000076122:Disks Large Homolog 4 Protein; D031541:Fluorescence Resonance Energy Transfer; D057809:HEK293 Cells; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins / Q000378:metabolism*; D008565:Membrane Proteins / Q000378:metabolism*; D009473:Neuronal Plasticity / Q000502:physiology; D051381:Rats; D016194:Receptors, N-Methyl-D-Aspartate / Q000378:metabolism*; D015398:Signal Transduction; D019061:src-Family Kinases / Q000502:physiology*
D054732:Calcium-Calmodulin-Dependent Protein Kinase Type 2; D002154:Calpain; D000076122:Disks Large Homolog 4 Protein; D047908:Intracellular Signaling Peptides and Proteins; D008565:Membrane Proteins; D016194:Receptors, N-Methyl-D-Aspartate; D019061:src-Family Kinases; C501449:Dlg4 protein, rat; C121001:NR2B NMDA receptor