TY - JOUR
T1 - SGP-1 increases dendritic and synaptic development dependent on synaptic activity
AU - Cove, Joshua
AU - Morales, Carlos R.
AU - Baranes, Danny
N1 - Funding Information:
Grant information: Canada Foundation of Innovation, Canadian Institutes for Health Research and the Tohman Foundation.
PY - 2006/12
Y1 - 2006/12
N2 - Neurotrophic factors are a group of secreted proteins which generally regulate neurite outgrowth and synaptic development. SGP-1 has been reported as a neurotrophic factor, though little is known of its effect on neurite outgrowth, and it is unknown whether SGP-1 affects synaptic development. We report here that SGP-1 is distributed in vesicle-like puncta in somas and dendrites of primary neurons in culture, and that SGP-1 is secreted in culture and is taken up by endocytosis in dendrites. Endogenous extracellular activity of SGP-1 promotes dendritic, but not axonal outgrowth. Furthermore, endogenous activity of SGP-1 increases synaptogenesis in hippocampal neurons as determined by measuring the density and size of synaptophysin puncta and by determining the density of dendritic spines, their surface expression of GluR2 and their immunoreactivity for GluR1. The effect of SGP-1 on the amount of postsynaptic receptors in dendritic spines depends on synaptic activity and apparently on activation of MAPK, as inhibition of either of these abolished the affect. Hence, SGP-1 has neurotrophic effects, increasing dendritic growth and promoting synaptic development in an activity-dependent fashion.
AB - Neurotrophic factors are a group of secreted proteins which generally regulate neurite outgrowth and synaptic development. SGP-1 has been reported as a neurotrophic factor, though little is known of its effect on neurite outgrowth, and it is unknown whether SGP-1 affects synaptic development. We report here that SGP-1 is distributed in vesicle-like puncta in somas and dendrites of primary neurons in culture, and that SGP-1 is secreted in culture and is taken up by endocytosis in dendrites. Endogenous extracellular activity of SGP-1 promotes dendritic, but not axonal outgrowth. Furthermore, endogenous activity of SGP-1 increases synaptogenesis in hippocampal neurons as determined by measuring the density and size of synaptophysin puncta and by determining the density of dendritic spines, their surface expression of GluR2 and their immunoreactivity for GluR1. The effect of SGP-1 on the amount of postsynaptic receptors in dendritic spines depends on synaptic activity and apparently on activation of MAPK, as inhibition of either of these abolished the affect. Hence, SGP-1 has neurotrophic effects, increasing dendritic growth and promoting synaptic development in an activity-dependent fashion.
KW - AMPA receptor
KW - Hippocampus
KW - Neurite outgrowth
KW - SGP-1
UR - http://www.scopus.com/inward/record.url?scp=33750975102&partnerID=8YFLogxK
U2 - 10.1016/j.neures.2006.08.008
DO - 10.1016/j.neures.2006.08.008
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C2 - 17050025
AN - SCOPUS:33750975102
SN - 0168-0102
VL - 56
SP - 372
EP - 385
JO - Neuroscience Research
JF - Neuroscience Research
IS - 4
ER -