title: Activity-independent regulation of dendrite patterning by postsynaptic density protein PSD-95.
abstract: Dendritic morphology determines many aspects of neuronal function, including action potential propagation and information processing. However, the question remains as to how distinct neuronal dendrite branching patterns are established. Here, we report that postsynaptic density-95 (PSD-95), a protein involved in dendritic spine maturation and clustering of synaptic signaling proteins, plays a novel role in regulating dendrite outgrowth and branching, independent of its synaptic functions. In immature neurons, overexpression of PSD-95 decreases the proportion of primary dendrites that undergo additional branching, resulting in a marked reduction of secondary dendrite number. Conversely, knocking down PSD-95 protein in immature neurons increases secondary dendrite number. The effect of PSD-95 is activity-independent and is antagonized by cypin, a nonsynaptic protein that regulates PSD-95 localization. Binding of cypin to PSD-95 correlates with formation of stable dendrite branches. Finally, overexpression of PSD-95 in COS-7 cells disrupts microtubule organization, indicating that PSD-95 may modulate microtubules to regulate dendritic branching. Whereas many factors have been identified which regulate dendrite number, our findings provide direct evidence that proteins primarily involved in synaptic functions can also play developmental roles in shaping how a neuron patterns its dendrite branches.
authors.affiliation: Department of Cell Biology and Neuroscience, Rutgers University, Piscataway, New Jersey 08854-8082, USA.
authors.forename: Erik I
authors.initials: EI
authors.lastname: Charych
authors.forename: Barbara F
authors.initials: BF
authors.lastname: Akum
authors.forename: Joshua S
authors.initials: JS
authors.lastname: Goldberg
authors.forename: Rebecka J
authors.initials: RJ
authors.lastname: Jörnsten
authors.forename: Christopher
authors.initials: C
authors.lastname: Rongo
authors.forename: James Q
authors.initials: JQ
authors.lastname: Zheng
authors.forename: Bonnie L
authors.initials: BL
authors.lastname: Firestein
mesh_terms: D000818:Animals; D019556:COS Cells; D049108:Cell Enlargement; D002478:Cells, Cultured; D002522:Chlorocebus aethiops; D003712:Dendrites / Q000502:physiology*; D000076122:Disks Large Homolog 4 Protein; D006624:Hippocampus / Q000166:cytology / Q000502:physiology; D047908:Intracellular Signaling Peptides and Proteins / Q000235:genetics; D008565:Membrane Proteins / Q000096:biosynthesis* / Q000235:genetics; D009419:Nerve Tissue Proteins / Q000096:biosynthesis / Q000235:genetics; D051381:Rats
chemical_list: D000076122:Disks Large Homolog 4 Protein; C501449:Dlg4 protein, rat; D047908:Intracellular Signaling Peptides and Proteins; D008565:Membrane Proteins; D009419:Nerve Tissue Proteins; C033652:postsynaptic density proteins