Variations associated with neurodevelopmental disorders affect ARF1 function and cortical development

ADP-ribosylation factors (ARFs) are a family of small GTPases that regulate vesicle trafficking and actin dynamics in cells. Recent genetic analyses have revealed associations between variations in ARF genes and neurodevelopmental disorders, although their pathophysiological significance remains unclear. In this study, we conducted biochemical, cell biological and in vivo analyses of ARF1 variants linked to neurodevelopmental disorders. The mant-GDP dissociation assay revealed that ARF1-p.R19C, -p.F51L, -p.R99C and -p.R99H exhibit higher GDP/GTP exchange activity compared to ARF1 wild type (WT). The GTPase-activating protein (GAP) increased the GTPase activity of WT, p.R19C, p.Y35H, p.F51L, p.P131L and p.P131R, but not of p.Y35D, p.T48I, p.R99C and p.R99H. The transient expression of p.R99C, p.R99H and p.K127E in mammalian cells resulted in the disruption of the Golgi apparatus. In utero electroporation-mediated gene transfer into the cortical neurons of embryonic mice demonstrated that p.R99C, p.R99H and p.K127E cause a migration defect. Expression of these variants resulted in the expansion of the Golgi apparatus in migrating cortical neurons. These findings suggest that the ARF1 variants linked to neurodevelopmental disorders, specifically p.R99C, p.R99H and p.K127E, disrupt the structure of the Golgi apparatus, thereby leading to a developmental defect of cortical neurons.