Adenylosuccinate lyase (ADSL) functions in de novo purine synthesis (DNPS) and the purine nucleotide cycle. ADSL deficiency (ADSLD) causes numerous neurodevelopmental pathologies, including microcephaly and autism spectrum disorder. ADSLD patients have normal serum purine nucleotide levels but exhibit accumulation of dephosphorylated ADSL substrates, S-Ado, and SAICAr, the latter being implicated in neurotoxic effects through unknown mechanisms. We examined the phenotypic effects of ADSL depletion in human cells and their relation to phenotypic outcomes. Using specific interventions to compensate for reduced purine levels or modulate SAICAr accumulation, we found that diminished AMP levels resulted in increased DNA damage signaling and cell cycle delays, while primary ciliogenesis was impaired specifically by loss of ADSL or administration of SAICAr. ADSL-deficient chicken and zebrafish embryos displayed impaired neurogenesis and microcephaly. Neuroprogenitor attrition in zebrafish embryos was rescued by pharmacological inhibition of DNPS, but not increased nucleotide concentration. Zebrafish also displayed phenotypes commonly linked to ciliopathies. Our results suggest that both reduced purine levels and impaired DNPS contribute to neurodevelopmental pathology in ADSLD and that defective ciliogenesis may influence the ADSLD phenotypic spectrum., ID was funded by the European Union’s Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie grant agreement no. 754510, THS, JL, and SP were funded by the Ministry of Science, Innovation and Universities (MCIU; PGC2018-095616-B-I00 to THS, PGC2018-099562-B-I00 to JL, and BFU2017-83562-P to SP), the
2017 SGR 1089 (AGAUR), FEDER, the Centres of Excellence Severo Ochoa award, and the CERCA Programme. THS was supported by the NIH Intramural Research Program, National Cancer Institute, Center for Cancer Research. MP was funded by grants from the Deutsche Forschungsgemeinschaft (DFG PH144/4-1 and PH144/6-1). MZ, OS, and VS were supported by Charles University, program PROGRES Q26/LF1. We would like to thank Biocev, First Faculty of Medicine, Charles University, for the opportunity to use their department’s equipment.

Raw microscopy data for Fig3B, 3E and 3S1 (.lif format) in a single zip file., Resources available on the publisher's site: https://doi.org/10.25452/figshare.plus.18309440.v1, Ministry of Science, Innovation and Universities BFU2017-83562-P, Peer reviewed

Here, we show that, in the developing spinal cord, after the early Wnt-mediated Tcf transcription activation that confers dorsal identity to neural stem cells, neurogenesis redirects β-catenin from the adherens junctions to the nucleus to stimulate Tcf-dependent transcription in a Wnt-independent manner. This new β-catenin activity regulates genes implicated in several aspects of contralateral axon growth, including axon guidance and adhesion. Using live imaging of ex-vivo chick neural tube, we showed that the nuclear accumulation of β-catenin and the rise in Tcf-dependent transcription both initiate before the dismantling of the adherens junctions and remain during the axon elongation process. Notably, we demonstrated that β-catenin activity in post-mitotic cells depends on TCF7L2 and is central to spinal commissural axon growth. Together, our results reveal Wnt-independent Tcf/β-catenin regulation of genes that control the growth and guidance of commissural axons in chick spinal cord., A.H. was supported by a Juan de la Cierva fellowship from Ministerio de Ciencia e Innovación (FJCI-2015-26175). A.O. was supported by a Ministerio de Economía y Competitividad pre-doctoral fellowship (BES-2015-072035). The work in S.P.’s laboratory was supported by Ministerio de Ciencia e Innovación (BFU2017-83562-P and PID2020-116806GB-I00). Open Access funding provided by Consejo Superior de Investigaciones Científicas. Deposited in PMC for immediate release., Peer reviewed

Vinculin is an actin-binding protein (ABP) that strengthens the connection between the actin cytoskeleton and adhesion complexes. It binds to β-catenin/N-cadherin complexes in apical adherens junctions (AJs), which maintain cell-to-cell adhesions, and to talin/integrins in the focal adhesions (FAs) that attach cells to the basal membrane. Here, we demonstrate that β-catenin targets vinculin to the apical AJs and the centrosome in the embryonic neural tube (NT). Suppression of vinculin slows down the basal-to-apical part of interkinetic nuclear migration (BAINM), arrests neural stem cells (NSCs) in the G2 phase of the cell cycle, and ultimately dismantles the apical actin cytoskeleton. In the NSCs, mitosis initiates when an internalized centrosome gathers with the nucleus during BAINM. Notably, our results show that the first centrosome to be internalized is the daughter centrosome, where β-catenin and vinculin accumulate, and that vinculin suppression prevents centrosome internalization. Thus, we propose that vinculin links AJs, the centrosome, and the actin cytoskeleton where actomyosin contraction forces are required., A. Herrera was supported by a Juan de la Cierva fellowship, MINECO #FJCI2015-26175. A. Ochoa was supported by a MEC pre-doctoral fellowship, MINECO #BES-2015-072035. The work in S. Pons’s
laboratory was supported by MINECO grant BFU2017-83562-P and MICIN grant PID2020-116806GB-I00. Open Access funding provided by CSIC., Peer reviewed