title: Regulation of dendritic spine morphogenesis by insulin receptor substrate 53, a downstream effector of Rac1 and Cdc42 small GTPases.
abstract: The small GTPases Rac1 and Cdc42 are key regulators of the morphogenesis of actin-rich dendritic spines in neurons. However, little is known about how activated Rac1/Cdc42 regulates dendritic spines. Insulin receptor substrate 53 (IRSp53), which is highly expressed in the postsynaptic density (PSD), is known to link activated Rac1/Cdc42 to downstream effectors for actin regulation in non-neural cells. Here, we report that IRSp53 interacts with two specific members of the PSD-95 family, PSD-95 and chapsyn-110/PSD-93, in brain. An IRSp53 mutant lacking the C-terminal PSD-95-binding motif shows significant loss of synaptic localization in cultured neurons. Overexpression of IRSp53 in cultured neurons increases the density of dendritic spines but does not affect their length or width. Conversely, short-interfering RNA-mediated knock-down of IRSp53 reduces the density, length, and width of spines. In addition, the density and size of spines are decreased by a dominant-negative IRSp53 with a point mutation in the Src homology 3 (SH3) domain and a dominant-negative proline-rich region of WAVE2 (Wiskott-Aldrich syndrome protein family Verprolin-homologous protein), a downstream effector of IRSp53 that binds to the SH3 domain of IRSp53. These results suggest that PSD-95 interaction is an important determinant of synaptic IRSp53 localization and that the SH3 domain of IRSp53 links activated Rac1/Cdc42 to downstream effectors for the regulation of spine morphogenesis.
authors.affiliation: National Creative Research Initiative Center for Synaptogenesis and Department of Biological Sciences, Korea Advanced Institute of Science and Technology, Daejeon 305-701, Korea.
authors.forename: Jeonghoon
authors.initials: J
authors.lastname: Choi
authors.forename: Jaewon
authors.initials: J
authors.lastname: Ko
authors.forename: Bence
authors.initials: B
authors.lastname: Racz
authors.forename: Alain
authors.initials: A
authors.lastname: Burette
authors.forename: Jae-Ran
authors.initials: JR
authors.lastname: Lee
authors.forename: Seho
authors.initials: S
authors.lastname: Kim
authors.forename: Moonseok
authors.initials: M
authors.lastname: Na
authors.forename: Hyun Woo
authors.initials: HW
authors.lastname: Lee
authors.forename: Karam
authors.initials: K
authors.lastname: Kim
authors.forename: Richard J
authors.initials: RJ
authors.lastname: Weinberg
authors.forename: Eunjoon
authors.initials: E
authors.lastname: Kim
mesh_terms: D048868:Adaptor Proteins, Signal Transducing; D000818:Animals; D001921:Brain / Q000254:growth & development / Q000378:metabolism; D002478:Cells, Cultured; D049229:Dendritic Spines / Q000378:metabolism / Q000502:physiology* / Q000648:ultrastructure; D000076122:Disks Large Homolog 4 Protein; D005455:Fluorescent Antibody Technique; D005799:Genes, Dominant; D047468:Immunoprecipitation; D047908:Intracellular Signaling Peptides and Proteins; D008565:Membrane Proteins; D008840:Microfilament Proteins / Q000502:physiology; D009024:Morphogenesis / Q000502:physiology; D046912:Multiprotein Complexes; D009419:Nerve Tissue Proteins / Q000096:biosynthesis / Q000502:physiology*; D017354:Point Mutation; D034741:RNA, Small Interfering; D051381:Rats; D011993:Recombinant Fusion Proteins; D020798:Two-Hybrid System Techniques; D051300:Wiskott-Aldrich Syndrome Protein Family; D020764:cdc42 GTP-Binding Protein / Q000502:physiology; D020830:rac1 GTP-Binding Protein / Q000502:physiology; D018909:src Homology Domains / Q000502:physiology
chemical_list: D048868:Adaptor Proteins, Signal Transducing; C119539:BAIAP2 protein, human; C503229:Baiap2 protein, rat; D000076122:Disks Large Homolog 4 Protein; C501449:Dlg4 protein, rat; D047908:Intracellular Signaling Peptides and Proteins; D008565:Membrane Proteins; D008840:Microfilament Proteins; C501451:Mpp2 protein, rat; D046912:Multiprotein Complexes; D009419:Nerve Tissue Proteins; D034741:RNA, Small Interfering; D011993:Recombinant Fusion Proteins; D051300:Wiskott-Aldrich Syndrome Protein Family; C033652:postsynaptic density proteins; D020764:cdc42 GTP-Binding Protein; D020830:rac1 GTP-Binding Protein