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Cereb Cortex. 2017 Jan 1;27(1):216-232. doi: 10.1093/cercor/bhw394.

Neurexins 1-3 Each Have a Distinct Pattern of Expression in the Early Developing Human Cerebral Cortex.

Author information

1
Institute of Neuroscience, Newcastle University, Framlington Place, Newcastle upon Tyne NE2 4HH, UK.
2
Institute of Genetic Medicine, Newcastle University, International Centre for Life, Parkway Drive, Newcastle upon Tyne NE1 3BZ, UK.
3
Present address: School of Healthcare Science, Manchester Metropolitan University, Manchester, M1 5GD, UK.
4
Present address: Wellcome Trust, Sanger Institute, Cambridge, CB10 1SA, UK.
5
Present address: MRC Centre for Regenerative Medicine, University of Edinburgh, Edinburgh, EH16 4UU, UK.

Abstract

Neurexins (NRXNs) are presynaptic terminal proteins and candidate neurodevelopmental disorder susceptibility genes; mutations presumably upset synaptic stabilization and function. However, analysis of human cortical tissue samples by RNAseq and quantitative real-time PCR at 8-12 postconceptional weeks, prior to extensive synapse formation, showed expression of all three NRXNs as well as several potential binding partners. However, the levels of expression were not identical; NRXN1 increased with age and NRXN2 levels were consistently higher than for NRXN3. Immunohistochemistry for each NRXN also revealed different expression patterns at this stage of development. NRXN1 and NRXN3 immunoreactivity was generally strongest in the cortical plate and increased in the ventricular zone with age, but was weak in the synaptogenic presubplate (pSP) and marginal zone. On the other hand, NRXN2 colocalized with synaptophysin in neurites of the pSP, but especially with GAP43 and CASK in growing axons of the intermediate zone. Alternative splicing modifies the role of NRXNs and we found evidence by RNAseq for exon skipping at splice site 4 and concomitant expression of KHDBRS proteins which control this splicing. NRXN2 may play a part in early cortical synaptogenesis, but NRXNs could have diverse roles in development including axon guidance, and intercellular communication between proliferating cells and/or migrating neurons.

KEYWORDS:

cortical development; neurexins; neurodevelopmental disorders; subplate

PMID:
28013231
PMCID:
PMC5654756
DOI:
10.1093/cercor/bhw394
[Indexed for MEDLINE]
Free PMC Article

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