The Nance-Horan syndrome protein NHS regulates cell migration persistence by organizing WAVE and N-WASP nucleation-promoting factor complexes.

The function of the NHS gene that is responsible for the Nance-Horan Syndrome has remained elusive at the cellular level. Using CRISPR/Cas9, we inactivated the NHS gene in MCF10A cells and characterized the isoforms expressed in these cells. NHS KO cells displayed reduced migration persistence, a phenotype that was fully rescued by the long isoform 1 (i1) that contains a N-terminal WAVE Homology Domain (WHD), but only partially rescued by the short isoform 2 (i2), which does not. Patient mutations resulting in NHS proteins truncated at their C-terminus also reduced the ability of NHS i1 to rescue migration persistence. Using Tandem Affinity Purification (TAP) of NHS i1 and mass spectrometry, we identified as major NHS partners, all subunits of the WAVE Regulatory Complex (WRC) except WAVE subunits themselves, indicating that the WHD of NHS assembles a WAVE Shell Complex (WSC). The Arp2/3 complex and the Nucleation Promoting Factor (NPF) WAVE that activates it are critical for migration persistence. To investigate the role of the NHS-containing WSC, we performed TAP of the ABI1 subunit in parental and NHS KO cells and identified differential partners associated with ABI1 only in parental cells, but not in NHS KO cells. The most abundant of these were the WIPF2/N-WASP complex, which together with the kinase ABL2, was also critical for migration persistence. These results suggest that NHS controls cell migration by remodeling NPF complexes and their higher order assembly.