ChangHui Pak1, 5, Tamas Danko1, 2, 5, Yingsha Zhang1, Jason Aoto1, Garret Anderson1, Stephan Maxeiner1, Fei Yi1, Marius Wernig2, 3, Thomas C. Sudhof1, 4
1 Department of Molecular and Cellular Physiology, Stanford University School of Medicine, 265 Campus Drive, Stanford, CA 94305, USA
2 Institute for Stem Cell Biology and Regenerative Medicine, Stanford University School of Medicine, 265 Campus Drive, Stanford, CA 94305, USA
3 Department of Pathology, Stanford University School of Medicine, 265 Campus Drive, Stanford, CA 94305, USA
4 Howard Hughes Medical Institute, Stanford University School of Medicine, 265 Campus Drive, Stanford, CA 94305, USA
5 Co-first author
Corresponding author : Thomas C. Sudhof
Summary
Heterozygous mutations of the NRXN1 gene, which encodes the presynaptic cell-adhesion molecule neurexin-1, were repeatedly associated with autism and schizophrenia. However, diverse clinical presentations of NRXN1 mutations in patients raise the question of whether heterozygous NRXN1 mutations alone directly impair synaptic function. To address this question under conditions that precisely control for genetic background, we generated human ESCs with different heterozygous conditional NRXN1 mutations and analyzed two different types of isogenic control and NRXN1 mutant neurons derived from these ESCs. Both heterozygous NRXN1 mutations selectively impaired neurotransmitter release in human neurons without changing neuronal differentiation or synapse formation. Moreover, both NRXN1 mutations increased the levels of CASK, a critical synaptic scaffolding protein that binds to neurexin-1. Our results show that, unexpectedly, heterozygous inactivation of NRXN1 directly impairs synaptic function in human neurons, and they illustrate the value of this conditional deletion approach for studying the functional effects of disease-associated mutations.