Premature expression of KCC2 in embryonic mice perturbs neural development by an ion transport-independent mechanism.
During neuronal maturation, the neuron-specific K-Cl co-transporter KCC2 lowers the intracellular chloride and thereby renders GABAergic transmission hyperpolarizing. Independently of its role as a co-transporter, KCC2 plays a crucial role in the maturation of dendritic spines, most probably via an interaction with the cytoskeleton-associated protein 4.1N. In this study, we show that neural-specific overexpression of KCC2 impairs the development of the neural tube- and neural crest-related structures in mouse embryos. At early stages (E9.5-11.5), the transgenic embryos had a thinner neural tube and abnormal body curvature. They displayed a reduced neuronal differentiation and altered neural crest cell pattern. At later stages (E11.5-15.5), the transgenic embryos had smaller brain structures and a distinctive cleft palate. Similar results were obtained using overexpression of a transport-inactive N-terminal-deleted variant of KCC2, implying that the effects were not dependent on KCC2's role as a K-Cl co-transporter. Interestingly, the neural tube of transgenic embryos had an aberrant cytoplasmic distribution of 4.1N and actin. This was corroborated in a neural stem cell line with ectopic expression of KCC2. Embryo phenotype and cell morphology were unaffected by a mutated variant of KCC2 which is unable to bind 4.1N. These results point to a role of KCC2 in neuronal differentiation and migration during early development mediated by its direct structural interactions with the neuronal cytoskeleton.
Horn
Zachi
Z
Neonatal Research Unit, Department of Women's and Children's Health, Karolinska Institutet, Stockholm, Sweden. zachi.horn@ki.se
Ringstedt
Thomas
T
Blaesse
Peter
P
Kaila
Kai
K
Herlenius
Eric
E
D000818:Animals; D002454:Cell Differentiation / Q000502:physiology; D002465:Cell Movement / Q000502:physiology; D002478:Cells, Cultured; D003599:Cytoskeleton / Q000378:metabolism / Q000648:ultrastructure; D004622:Embryo, Mammalian / Q000033:anatomy & histology / Q000502:physiology*; D005260:Female; D018507:Gene Expression Regulation, Developmental; D006801:Humans; D017136:Ion Transport / Q000502:physiology*; D051379:Mice; D008822:Mice, Transgenic; D009474:Neurons / Q000166:cytology / Q000502:physiology*; D011247:Pregnancy; D027981:Symporters / Q000235:genetics / Q000378:metabolism*; D005680:gamma-Aminobutyric Acid / Q000378:metabolism; D000096922:K Cl- Cotransporters
D027981:Symporters; D005680:gamma-Aminobutyric Acid; D000096922:K Cl- Cotransporters