TrkB has a cell-autonomous role in the establishment of hippocampal Schaffer collateral synapses.
Neurotrophin signaling has been implicated in the processes of synapse formation and plasticity. To gain additional insight into the mechanism of BDNF and TrkB influence on synapse formation and synaptic plasticity, we generated a conditional knock-out for TrkB using the cre/loxp system. Using three different cre-expressing transgenic mice, three unique spatial and temporal configurations of TrkB deletion were obtained with regard to the hippocampal Schaffer collateral synapse. We compare synapse formation in mutants in which TrkB is ablated either in presynaptic or in both presynaptic and postsynaptic cells at early developmental or postdevelopmental time points. Our results indicate a requirement for TrkB at both the presynaptic and postsynaptic sites during development. In the absence of TrkB, synapse numbers were significantly reduced. In vivo ablation of TrkB after synapse formation did not affect synapse numbers. In primary hippocampal cultures, deletion of TrkB in only the postsynaptic cell, before synapse formation, also resulted in deficits of synapse formation. We conclude that TrkB signaling has a cell-autonomous role required for normal development of both presynaptic and postsynaptic components of the Schaffer collateral synapse.
Luikart
Bryan W
BW
Center for Developmental Biology and Kent Waldrep Foundation Center for Basic Neuroscience Research on Nerve Growth and Regeneration, University of Texas Southwestern Medical Center, Dallas, Texas 75390-9133, USA.
Nef
Serge
S
Virmani
Tuhin
T
Lush
Mark E
ME
Liu
Yajuan
Y
Kavalali
Ege T
ET
Parada
Luis F
LF
D000818:Animals; D000831:Animals, Newborn; D015153:Blotting, Western / Q000379:methods; D054732:Calcium-Calmodulin-Dependent Protein Kinase Type 2; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000378:metabolism; D002452:Cell Count / Q000379:methods; D002478:Cells, Cultured; D049229:Dendritic Spines / Q000378:metabolism; D000076122:Disks Large Homolog 4 Protein; D019706:Excitatory Postsynaptic Potentials / Q000187:drug effects / Q000502:physiology / Q000528:radiation effects; D005786:Gene Expression Regulation / Q000502:physiology; D005904:Glial Fibrillary Acidic Protein / Q000378:metabolism; D051528:Guanylate Kinases; D006624:Hippocampus / Q000166:cytology*; D007150:Immunohistochemistry / Q000379:methods; D017403:In Situ Hybridization / Q000379:methods; D007211:Indoles; D047908:Intracellular Signaling Peptides and Proteins / Q000378:metabolism; D008564:Membrane Potentials / Q000502:physiology; D008565:Membrane Proteins / Q000378:metabolism; D051379:Mice; D018345:Mice, Knockout; D009474:Neurons / Q000166:cytology / Q000378:metabolism*; D018408:Patch-Clamp Techniques / Q000379:methods; D010751:Phosphopyruvate Hydratase / Q000378:metabolism; D017729:Presynaptic Terminals / Q000502:physiology* / Q000648:ultrastructure; D020813:Receptor, trkB / Q000172:deficiency / Q000235:genetics / Q000502:physiology*; D017470:Receptors, Glutamate / Q000145:classification / Q000378:metabolism; D013569:Synapses / Q000502:physiology* / Q000648:ultrastructure; D016704:Synapsins / Q000378:metabolism; D001616:beta-Galactosidase / Q000378:metabolism
D000076122:Disks Large Homolog 4 Protein; C501447:Dlg4 protein, mouse; D005904:Glial Fibrillary Acidic Protein; D007211:Indoles; D047908:Intracellular Signaling Peptides and Proteins; D008565:Membrane Proteins; D017470:Receptors, Glutamate; D016704:Synapsins; C007293:DAPI; D020813:Receptor, trkB; D054732:Calcium-Calmodulin-Dependent Protein Kinase Type 2; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D051528:Guanylate Kinases; D001616:beta-Galactosidase; D010751:Phosphopyruvate Hydratase