Synaptic abnormalities and cytoplasmic glutamate receptor aggregates in contactin associated protein-like 2/Caspr2 knockout neurons.
Central glutamatergic synapses and the molecular pathways that control them are emerging as common substrates in the pathogenesis of mental disorders. Genetic variation in the contactin associated protein-like 2 (CNTNAP2) gene, including copy number variations, exon deletions, truncations, single nucleotide variants, and polymorphisms have been associated with intellectual disability, epilepsy, schizophrenia, language disorders, and autism. CNTNAP2, encoded by Cntnap2, is required for dendritic spine development and its absence causes disease-related phenotypes in mice. However, the mechanisms whereby CNTNAP2 regulates glutamatergic synapses are not known, and cellular phenotypes have not been investigated in Cntnap2 knockout neurons. Here we show that CNTNAP2 is present in dendritic spines, as well as axons and soma. Structured illumination superresolution microscopy reveals closer proximity to excitatory, rather than inhibitory synaptic markers. CNTNAP2 does not promote the formation of synapses and cultured neurons from Cntnap2 knockout mice do not show early defects in axon and dendrite outgrowth, suggesting that CNTNAP2 is not required at this stage. However, mature neurons from knockout mice show reduced spine density and levels of GluA1 subunits of AMPA receptors in spines. Unexpectedly, knockout neurons show large cytoplasmic aggregates of GluA1. Here we characterize, for the first time to our knowledge, synaptic phenotypes in Cntnap2 knockout neurons and reveal a novel role for CNTNAP2 in GluA1 trafficking. Taken together, our findings provide insight into the biological roles of CNTNAP2 and into the pathogenesis of CNTNAP2-associated neuropsychiatric disorders.
Departments of Physiology and.
Olga
O
Varea
Departments of Physiology and.
Maria Dolores
MD
Martin-de-Saavedra
Departments of Physiology and.
Katherine J
KJ
Kopeikina
Departments of Physiology and.
Britta
B
Schürmann
Departments of Physiology and.
Hunter J
HJ
Fleming
Departments of Physiology and.
Jessica M
JM
Fawcett-Patel
Departments of Physiology and.
Anthony
A
Bach
Department of Neuroscience, Korea Advanced Institute of Science and Technology, 305-701 Daejeon, South Korea;
Seil
S
Jang
Department of Molecular Cell Biology, Weizmann Institute of Science, 76100 Rehovot, Israel.
Elior
E
Peles
Department of Neuroscience, Korea Advanced Institute of Science and Technology, 305-701 Daejeon, South Korea; Center for Synaptic Brain Dysfunctions, Institute of Basic Science, 305-701 Daejeon, South Korea; and.
Eunjoon
E
Kim
Departments of Physiology and Psychiatry and Behavioral Sciences, Northwestern University Feinberg School of Medicine, Chicago, IL 60611; p-penzes@northwestern.edu.
Peter
P
Penzes
D000818:Animals; D001369:Axons / Q000502:physiology; D002478:Cells, Cultured; D018920:Coculture Techniques; D003593:Cytoplasm / Q000378:metabolism*; D018507:Gene Expression Regulation, Developmental; D005838:Genotype; D049452:Green Fluorescent Proteins / Q000378:metabolism; D057809:HEK293 Cells; D006801:Humans; D008565:Membrane Proteins / Q000235:genetics* / Q000502:physiology*; D051379:Mice; D018345:Mice, Knockout; D018613:Microscopy, Confocal; D008856:Microscopy, Fluorescence; D009419:Nerve Tissue Proteins / Q000235:genetics* / Q000502:physiology*; D009422:Nervous System Diseases / Q000378:metabolism; D009474:Neurons / Q000378:metabolism; D010641:Phenotype; D018091:Receptors, AMPA / Q000378:metabolism; D017470:Receptors, Glutamate / Q000378:metabolism*; D012559:Schizophrenia / Q000378:metabolism; D013569:Synapses / Q000378:metabolism / Q000473:pathology*
D049452:Green Fluorescent Proteins; D008565:Membrane Proteins; D009419:Nerve Tissue Proteins; D018091:Receptors, AMPA; D017470:Receptors, Glutamate; C568163:CNTNAP2 protein, mouse
AMPA; CNTNAP2; GluA1; schizophrenia; synapse