Neural crest-related NXPH1/α-NRXN signaling opposes neuroblastoma malignancy by inhibiting organotropic metastasis

Neuroblastoma is a pediatric cancer that can present as low- or high-risk tumors (LR-NBs and HR-NBs), the latter group showing poor prognosis due to metastasis and strong resistance to current therapy. Whether LR-NBs and HR-NBs differ in the way they exploit the transcriptional program underlying their neural crest, sympatho-adrenal origin remains unclear. Here, we identified the transcriptional signature distinguishing LR-NBs from HR-NBs, which consists mainly of genes that belong to the core sympatho-adrenal developmental program and are associated with favorable patient prognosis and with diminished disease progression. Gain- and loss-of-function experiments revealed that the top candidate gene of this signature, Neurexophilin-1 (NXPH1), has a dual impact on NB cell behavior in vivo: whereas NXPH1 and its receptor α-NRXN1 promote NB tumor growth by stimulating cell proliferation, they conversely inhibit organotropic colonization and metastasis. As suggested by RNA-seq analyses, these effects might result from the ability of NXPH1/α-NRXN signalling to restrain the conversion of NB cells from an adrenergic state to a mesenchymal one. Our findings thus uncover a transcriptional module of the sympatho-adrenal program that opposes neuroblastoma malignancy by impeding metastasis, and pinpoint NXPH1/α-NRXN signaling as a promising target to treat HR-NBs.This work was supported by grants from the Ministerio de Ciencia e Innovacion, Gobierno de España (MCINN; BFU2016-81887-REDT and BFU2016-77498-P) and the Asociación Española Contra el Cancer (AECC CI_2016) to EM, from the Fondo de Investigación en Salud (FIS) - Instituto de salud Carlos III (PI14/00038) and the NEN association (Association of Families and Friends of Patients with Neuroblastoma) to CL, from the Instituto de Salud Carlos III-FSE (MS17/00037; PI18/00014; PI21/00020) to TC-T, from Instituto de Salud Carlos III (CP22/00127, co-funded by European Social Fund “Investing in your future”) to BMJ, from the Agence Nationale pour la Recherche (ANR-17-CE14-0023-01, ANR-17-CE14-0009-02) and the city of Paris (Emergence program) to ELG, from ISCIII-FEDER (CP13/00189 and CPII18/00009) to AMC. LF received a PhD fellowship from the Spanish Ministry of Science, Education and Universities (FPU AP2012-2222). LT-D was funded by a FPI Fellowship (PRE2019-088005). GLD was supported by the Asociación Española Contra el Cancer (AECC #AIO14142105LED)

Shh-mediated centrosomal recruitment of PKA promotes symmetric proliferative neuroepithelial cell division

Tight control of the balance between self-expanding symmetric and self-renewing asymmetric neural progenitor divisions is crucial to regulate the number of cells in the developing central nervous system. We recently demonstrated that Sonic hedgehog (Shh) signalling is required for the expansion of motor neuron progenitors by maintaining symmetric divisions. Here we show that activation of Shh/Gli signalling in dividing neuroepithelial cells controls the symmetric recruitment of PKA to the centrosomes that nucleate the mitotic spindle, maintaining symmetric proliferative divisions. Notably, Shh signalling upregulates the expression of pericentrin, which is required to dock PKA to the centrosomes, which in turn exerts a positive feedback onto Shh signalling. Thus, by controlling centrosomal protein assembly, we propose that Shh signalling overcomes the intrinsic asymmetry at the centrosome during neuroepithelial cell division, thereby promoting self-expanding symmetric divisions and the expansion of the progenitor pool.The work in E.M.’s laboratory was supported by grants BFU2013-46477-P and BFU2014-55738-REDT.Peer reviewe

Delamination of neural crest cells requires transient and reversible Wnt inhibition mediated by Dact1/2

Delamination of neural crest (NC) cells is a bona fide physiological model of epithelial-to-mesenchymal transition (EMT), a process that is influenced by Wnt/β-catenin signalling. Using two in vivo models, we show that Wnt/β-catenin signalling is transiently inhibited at the time of NC delamination. In attempting to define the mechanism underlying this inhibition, we found that the scaffold proteins Dact1 and Dact2, which are expressed in pre-migratory NC cells, are required for NC delamination in Xenopus and chick embryos, whereas they do not affect the motile properties of migratory NC cells. Dact1/2 inhibit Wnt/β-catenin signalling upstream of the transcriptional activity of T cell factor (TCF), which is required for EMT to proceed. Dact1/2 regulate the subcellular distribution of β-catenin, preventing β-catenin from acting as a transcriptional coactivator to TCF, yet without affecting its stability. Together, these data identify a novel yet important regulatory element that inhibits β-catenin signalling, which then affects NC delamination.This work was supported by the Medical Research Council [MR/J000655/1 and MR/ M010465 to R.M.]; the Biotechnology and Biological Sciences Research Council (BBSRC) [M008517 to R.M.]; the Ministerio de Economı́a y Competitividad [BFU2011-24099 to S.P.; BFU2013-46477-P and BFU2014-55738-REDT to E.M.].Peer Reviewe

Modeling survival curves of Anisakis L3 after isothermal heat treatments at lethal temperatures

Even though anisakiasis is considered, nowadays, a significant threat to public health all over the world, no attempt has been made up to date to mathematically describe the thermal susceptibility of Anisakis larvae in the third stage (L3). To fill this gap, in this paper, more than 10,000 free (non-encysted) Anisakis L3 were individually heat treated in a thermal cycler at temperatures between 44 °C and 61 °C for different exposure times. After heat exposition, viability was assessed in each larva, survival curves at isothermal conditions were derived, and the effectiveness of four kinetic models (fundamental kinetic model, Mafart model, and probit and logit models) in describing these curves was tested. Evaluation of larvae viability after heat exposition revealed sigmoidal survival curves that increased their steepness with temperature. Of the four models tested, the Mafart model was the one that best fitted the data only differing from the observed survival ratios by 0.12 units on average. Validation experiments performed at temperatures different to those used to create the model corroborated its predictive capacity. Future efforts should be focused in predicting larvae viability at non-isothermal conditions as those occurring during fish cooking.The work has been financed with the project ‘Mapping the effect of heating regimes on Anisakis death and fate of their allergens in fish muscle. Development of a decision support tool for optimal processing (HEATSAKIS)’. Reference: PID 2020-119201RB-I00/AEI/10.13039/501100011033. T.Peer reviewe

Cell intercalation driven by SMAD3 underlies secondary neural tube formation

Body axis elongation is a hallmark of the vertebrate embryo, involving the architectural remodeling of the tail bud. Although it is clear how neuromesodermal progenitors (NMPs) contribute to embryo elongation, the dynamic events that lead to de novo lumen formation and that culminate in the formation of a 3-dimensional, neural tube from NMPs, are poorly understood. Here, we used in vivo imaging of the chicken embryo to show that cell intercalation downstream of TGF-β/SMAD3 signaling is required for secondary neural tube formation. Our analysis describes the events in embryo elongation including lineage restriction, the epithelial-to-mesenchymal transition of NMPs, and the initiation of lumen formation. We show that the resolution of a single, centrally positioned lumen, which occurs through the intercalation of central cells, requires SMAD3/Yes-associated protein (YAP) activity. We anticipate that these findings will be relevant to understand caudal, skin-covered neural tube defects, among the most frequent birth defects detected in humans.The work in EM’s laboratory was supported by grants BFU2016-77498-P and RED2018-102553-T. EGG was recipient of a BES-2014-068589 PhD scholarship. JBA is a recipient of a BES-2017-080050 PhD scholarship

A SMAD1/5-YAP signalling module drives radial glia self-amplification and growth of the developing cerebral cortex

The growth and evolutionary expansion of the cerebral cortex are defined by the spatial-temporal production of neurons, which itself depends on the decision of radial glial cells (RGCs) to self-amplify or to switch to neurogenic divisions. The mechanisms regulating these RGC fate decisions are still incompletely understood. Here, we describe a novel and evolutionarily conserved role of the canonical BMP transcription factors SMAD1/5 in controlling neurogenesis and growth during corticogenesis. Reducing the expression of both SMAD1 and SMAD5 in neural progenitors at early mouse cortical development caused microcephaly and an increased production of early-born cortical neurons at the expense of late-born ones, which correlated with the premature differentiation and depletion of the pool of cortical progenitors. Gain- and loss-of-function experiments performed during early cortical neurogenesis in the chick revealed that SMAD1/5 activity supports self-amplifying RGC divisions and restrains the neurogenic ones. Furthermore, we demonstrate that SMAD1/5 stimulate RGC self-amplification through the positive post-transcriptional regulation of the Hippo signalling effector YAP. We anticipate this SMAD1/5-YAP signalling module to be fundamental in controlling growth and evolution of the amniote cerebral cortex.The work in M.L.A.’s and E.M.’s laboratories was supported by the Ministerio de Ciencia e Innovacion, Gobierno de España (MCINN; grants SAF2016-77971-R, RED2018-102553 and BFU2016-77498-P). I.P. received a PhD fellowship from the Ministerio de Economía, Industria y Competitividad, Gobierno de España (MINEICO, BES2014-069217). A.E.-C. was supported by Instituto de Salud Carlos III (MINEICO, PT17/0009/0019) and the European Regional Development Fund (FEDER). G.L.D. was supported by the Fundación Científica Asociación Española Contra el Cáncer (AIO14142105LED)

E proteins sharpen neurogenesis by modulating proneural bHLH transcription factors’ activity in an E-box-dependent manner

Class II HLH proteins heterodimerize with class I HLH/E proteins to regulate transcription. Here, we show that E proteins sharpen neurogenesis by adjusting the neurogenic strength of the distinct proneural proteins. We find that inhibiting BMP signaling or its target ID2 in the chick embryo spinal cord, impairs the neuronal production from progenitors expressing ATOH1/ASCL1, but less severely that from progenitors expressing NEUROG1/2/PTF1a. We show this context-dependent response to result from the differential modulation of proneural proteins’ activity by E proteins. E proteins synergize with proneural proteins when acting on CAGSTG motifs, thereby facilitating the activity of ASCL1/ATOH1 which preferentially bind to such motifs. Conversely, E proteins restrict the neurogenic strength of NEUROG1/2 by directly inhibiting their preferential binding to CADATG motifs. Since we find this mechanism to be conserved in corticogenesis, we propose this differential co-operation of E proteins with proneural proteins as a novel though general feature of their mechanism of action.Asociación Española Contra el Cáncer AIO2014 Gwenvael Le Dreau Consejo Nacional de Ciencia y Tecnologı´a Rene´ Escalona Ministerio de Educación, Cultura y Deporte #FPU13/01384 Raquel Fueyo Ministerio de Economía y Competitividad #FJCI-2015-26175 Antonio Herrera Ministerio de Economía y Competitividad BFU2014-53633-P Sebastian Pons Ministerio de Economı´a y Competitividad BFU2015-69248-P Marian A Martinez-Balbas Fondation Jerome Lejeune Fondation Jerome Lejeune.2016 Marian A Martinez-Balbas Ministerio de Economía y Competitividad BFU2016-81887-REDT Elisa Marti Ministerio de Economía y Competitividad BFU2016-77498-P Elisa MartiPeer reviewe