title: Bi-directional control of motor neuron dendrite remodeling by the calcium permeability of AMPA receptors.
abstract: Motor neurons express particularly high levels of the AMPA receptor subunit GluR1(Q)flip (GluR1(Q)i) during the period in early postnatal life when their dendritic tree grows and becomes more branched. To investigate how GluR1-containing AMPA receptors contribute to dendrite morphogenesis, we characterized a mutant form of GluR1 (containing a histidine in the Q/R editing site) with unique electrophysiological properties. Most notably, AMPA receptors assembled from GluR1(H)i display less calcium permeability than AMPA receptors assembled from GluR1(Q)i. Expression of GluR1(Q)i in vivo or in vitro led to an increase in dendrite branching with no net change in the overall tree size while GluR1(H)i led to a loss of branches and a net reduction in overall tree size. GluR1(H)i-dependent dendrite atrophy is mediated by protein phosphatase 2B. The results suggest that the electrophysiological properties of cell surface AMPA receptors, specifically their permeability to calcium, can be a central determinant of whether the dendrites undergo activity-dependent branching or atrophy.
authors.affiliation: Department of Anatomy, College of Medicine, Chungbuk National University, Cheong-ju 361-763, Republic of Korea.
authors.forename: Goo-Bo
authors.initials: GB
authors.lastname: Jeong
authors.forename: Markus
authors.initials: M
authors.lastname: Werner
authors.forename: Valeswara-Rao
authors.initials: VR
authors.lastname: Gazula
authors.forename: Takayuki
authors.initials: T
authors.lastname: Itoh
authors.forename: Melinda
authors.initials: M
authors.lastname: Roberts
authors.forename: Samuel
authors.initials: S
authors.lastname: David
authors.forename: Bryan
authors.initials: B
authors.lastname: Pfister
authors.forename: Akiva
authors.initials: A
authors.lastname: Cohen
authors.forename: Rachael L
authors.initials: RL
authors.lastname: Neve
authors.forename: Michael
authors.initials: M
authors.lastname: Hollmann
authors.forename: Robert
authors.initials: R
authors.lastname: Kalb
mesh_terms: D000818:Animals; D002118:Calcium / Q000378:metabolism*; D002463:Cell Membrane Permeability; D002478:Cells, Cultured; D003712:Dendrites / Q000378:metabolism* / Q000648:ultrastructure*; D005260:Female; D008297:Male; D009046:Motor Neurons / Q000166:cytology* / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley; D018091:Receptors, AMPA / Q000378:metabolism*; D014982:Xenopus laevis
chemical_list: D018091:Receptors, AMPA; D002118:Calcium