title: An ion transport-independent role for the cation-chloride cotransporter KCC2 in dendritic spinogenesis in vivo.
abstract: The neuron-specific K-Cl cotransporter, KCC2, is highly expressed in the vicinity of excitatory synapses in pyramidal neurons, and recent in vitro data suggest that this protein plays a role in the development of dendritic spines. The in vivo relevance of these observations is, however, unknown. Using in utero electroporation combined with post hoc iontophoretic injection of Lucifer Yellow, we show that premature expression of KCC2 induces a highly significant and permanent increase in dendritic spine density of layer 2/3 pyramidal neurons in the somatosensory cortex. Whole-cell recordings revealed that this increased spine density is correlated with an enhanced spontaneous excitatory activity in KCC2-transfected neurons. Precocious expression of the N-terminal deleted form of KCC2, which lacks the chloride transporter function, also increased spine density. In contrast, no effect on spine density was observed following in utero electroporation of a point mutant of KCC2 (KCC2-C568A) where both the cotransporter function and the interaction with the cytoskeleton are disrupted. Transfection of the C-terminal domain of KCC2, a region involved in the interaction with the dendritic cytoskeleton, also increased spine density. Collectively, these results demonstrate a role for KCC2 in excitatory synaptogenesis in vivo through a mechanism that is independent of its ion transport function.
authors.affiliation: Center for Psychiatric Neurosciences, Department of Psychiatry, Lausanne University Hospital, 1008 Prilly-Lausanne, Switzerland.
authors.forename: Hubert
authors.initials: H
authors.lastname: Fiumelli
authors.forename: Adrian
authors.initials: A
authors.lastname: Briner
authors.forename: Martin
authors.initials: M
authors.lastname: Puskarjov
authors.forename: Peter
authors.initials: P
authors.lastname: Blaesse
authors.forename: Bebyanda Jt
authors.initials: BJ
authors.lastname: Belem
authors.forename: Alex G
authors.initials: AG
authors.lastname: Dayer
authors.forename: Kai
authors.initials: K
authors.lastname: Kaila
authors.forename: Jean-Luc
authors.initials: JL
authors.lastname: Martin
authors.forename: Laszlo
authors.initials: L
authors.lastname: Vutskits
mesh_terms: D000818:Animals; D049229:Dendritic Spines / Q000378:metabolism*; D018274:Electroporation; D007150:Immunohistochemistry; D055495:Neurogenesis / Q000502:physiology*; D018408:Patch-Clamp Techniques; D017966:Pyramidal Cells / Q000254:growth & development* / Q000378:metabolism*; D051381:Rats; D017208:Rats, Wistar; D013003:Somatosensory Cortex / Q000254:growth & development / Q000378:metabolism; D027981:Symporters / Q000378:metabolism*; D014162:Transfection; D000096922:K Cl- Cotransporters
chemical_list: D027981:Symporters; D000096922:K Cl- Cotransporters