ojoplano-mediated basal constriction is essential for optic cup morphogenesis

11 páginas, 7 figuras. To the memory of Dr José-Santiago Martínez-Vinjoy. Supplementary material for this article is available at http://dev.biologists.org/cgi/content/full/136/13/2165/DC1Although the vertebrate retina is a well-studied paradigm for organogenesis, the morphogenetic mechanisms that carve the architecture of the vertebrate optic cup remain largely unknown. Understanding how the hemispheric shape of an eye is formed requires addressing the fundamental problem of how individual cell behaviour is coordinated to direct epithelial morphogenesis. Here, we analyze the role of ojoplano (opo), an uncharacterized gene whose human ortholog is associated with orofacial clefting syndrome, in the morphogenesis of epithelial tissues. Most notably, when opo is mutated in medaka fish, optic cup folding is impaired. We characterize optic cup morphogenesis in vivo and determine at the cellular level how opo affects this process. opo encodes a developmentally regulated transmembrane protein that localizes to compartments of the secretory pathway and to basal end-feet of the neuroepithelial precursors. We show that Opo regulates the polarized localization of focal adhesion components to the basal cell surface. Furthermore, tissue-specific interference with integrin-adhesive function impairs optic cup folding, resembling the ocular phenotype observed in opo mutants. We propose a model of retinal morphogenesis whereby opo-mediated formation of focal contacts is required to transmit the mechanical tensions that drive the macroscopic folding of the vertebrate optic cup.This work was supported by grants from the Deutsche Forschungsgemeinschaft, Collaborative Research Centre 488, the EU and HFSPO to J.W.; and MEC:BFU2008-04362/BMC to J.R.M.-M.Peer reviewe

Ubiquitin-specific protease-like 1 (USPL1) is a SUMO isopeptidase with essential, non-catalytic functions.

Isopeptidases are essential regulators of protein ubiquitination and sumoylation. However, only two families of SUMO isopeptidases are at present known. Here, we report an activity-based search with the suicide inhibitor haemagglutinin (HA)-SUMO-vinylmethylester that led to the identification of a surprising new SUMO protease, ubiquitin-specific protease-like 1 (USPL1). Indeed, USPL1 neither binds nor cleaves ubiquitin, but is a potent SUMO isopeptidase both in vitro and in cells. C13orf22l—an essential but distant zebrafish homologue of USPL1—also acts on SUMO, indicating functional conservation. We have identified invariant USPL1 residues required for SUMO binding and cleavage. USPL1 is a low-abundance protein that colocalizes with coilin in Cajal bodies. Its depletion does not affect global sumoylation, but causes striking coilin mislocalization and impairs cell proliferation, functions that are not dependent on USPL1 catalytic activity. Thus, USPL1 represents a third type of SUMO protease, with essential functions in Cajal body biology

Pcdh18a regulates endocytosis of E-cadherin during axial mesoderm development in zebrafish

The notochord defines the axial structure of all vertebrates during development. Notogenesis is a result of major cell reorganization in the mesoderm, the convergence and the extension of the axial cells. However, it is currently not fully understood how these processes act together in a coordinated way during notochord formation. The prechordal plate is an actively migrating cell population in the central mesoderm anterior to the trailing notochordal plate cells. We show that prechordal plate cells express Protocadherin 18a (Pcdh18a), a member of the cadherin superfamily. We find that Pcdh18a-mediated recycling of E-cadherin adhesion complexes transforms prechordal plate cells into a cohesive and fast migrating cell group. In turn, the prechordal plate cells subsequently instruct the trailing mesoderm. We simulated cell migration during early mesoderm formation using a lattice-based mathematical framework and predicted that the requirement for an anterior, local motile cell cluster could guide the intercalation and extension of the posterior, axial cells. Indeed, a grafting experiment validated the prediction and local Pcdh18a expression induced an ectopic prechordal plate-like cell group migrating towards the animal pole. Our findings indicate that the Pcdh18a is important for prechordal plate formation, which influences the trailing mesodermal cell sheet by orchestrating the morphogenesis of the notochord

Differences in vertebrate microRNA expression

MicroRNAs (miRNAs) attenuate gene expression by means of translational inhibition and mRNA degradation. They are abundant, highly conserved, and predicted to regulate a large number of transcripts. Several hundred miRNA classes are known, and many are associated with cell proliferation and differentiation. Many exhibit tissue-specific expression, which aids in evaluating their functions, and it has been assumed that their high level of sequence conservation implies a high level of expression conservation. A limited amount of data supports this, although discrepancies do exist. By comparing the expression of ≈100 miRNAs in medaka and chicken with existing data for zebrafish and mouse, we conclude that the timing and location of miRNA expression is not strictly conserved. In some instances, differences in expression are associated with changes in miRNA copy number, genomic context, or both between species. Variation in miRNA expression is more pronounced the greater the differences in physiology, and it is enticing to speculate that changes in miRNA expression may play a role in shaping the physiological differences produced during animal development

4DXpress: a database for cross-species expression pattern comparisons

In the major animal model species like mouse, fish or fly, detailed spatial information on gene expression over time can be acquired through whole mount in situ hybridization experiments. In these species, expression patterns of many genes have been studied and data has been integrated into dedicated model organism databases like ZFIN for zebrafish, MEPD for medaka, BDGP for Drosophila or GXD for mouse. However, a central repository that allows users to query and compare gene expression patterns across different species has not yet been established. Therefore, we have integrated expression patterns for zebrafish, Drosophila, medaka and mouse into a central public repository called 4DXpress (expression database in four dimensions). Users can query anatomy ontology-based expression annotations across species and quickly jump from one gene to the orthologues in other species. Genes are linked to public microarray data in ArrayExpress. We have mapped developmental stages between the species to be able to compare developmental time phases. We store the largest collection of gene expression patterns available to date in an individual resource, reflecting 16 505 annotated genes. 4DXpress will be an invaluable tool for developmental as well as for computational biologists interested in gene regulation and evolution. 4DXpress is available at http://ani.embl.de/4DXpress

Characterization of the neural stem cell gene regulatory network identifies OLIG2 as a multifunctional regulator of self-renewal

The gene regulatory network (GRN) that supports neural stem cell (NS cell) self-renewal has so far been poorly characterized. Knowledge of the central transcription factors (TFs), the noncoding gene regulatory regions that they bind to, and the genes whose expression they modulate will be crucial in unlocking the full therapeutic potential of these cells. Here, we use DNase-seq in combination with analysis of histone modifications to identify multiple classes of epigenetically and functionally distinct cis-regulatory elements (CREs). Through motif analysis and ChIP-seq, we identify several of the crucial TF regulators of NS cells. At the core of the network are TFs of the basic helix-loop-helix (bHLH), nuclear factor I (NFI), SOX, and FOX families, with CREs often densely bound by several of these different TFs. We use machine learning to highlight several crucial regulatory features of the network that underpin NS cell self-renewal and multipotency. We validate our predictions by functional analysis of the bHLH TF OLIG2. This TF makes an important contribution to NS cell self-renewal by concurrently activating pro-proliferation genes and preventing the untimely activation of genes promoting neuronal differentiation and stem cell quiescence.Welcome Trust grants: (WT095908, WT098051), FEBS Long-Term Fellowship, Medical Research Council Grant-in-Aid (U117570528)

Methods and rationale of the DISCOVER CKD global observational study

Background: Real-world data for patients with chronic kidney disease (CKD), specifically pertaining to clinical management, metabolic control, treatment patterns, quality of life (QoL) and dietary patterns, are limited. Understanding these gaps using real-world, routine care data will improve our understanding of the challenges and consequences faced by patients with CKD, and will facilitate the long-term goal of improving their management and prognosis. Methods: DISCOVER CKD follows an enriched hybrid study design, with both retrospective and prospective patient cohorts, integrating primary and secondary data from patients with CKD from China, Italy, Japan, Sweden, the UK and the USA. Data will be prospectively captured over a 3-year period from >1000 patients with CKD who will be followed up for at least 1 year via electronic case report form entry during routine clinical visits and also via a mobile/tablet-based application, enabling the capture of patient-reported outcomes (PROs). In-depth interviews will be conducted in a subset of ∼100 patients. Separately, secondary data will be retrospectively captured from >2 000 000 patients with CKD, extracted from existing datasets and registries. Results: The DISCOVER CKD program captures and will report on patient demographics, biomarker and laboratory measurements, medical histories, clinical outcomes, healthcare resource utilization, medications, dietary patterns, physical activity and PROs (including QoL and qualitative interviews). Conclusions: The DISCOVER CKD program will provide contemporary real-world insight to inform clinical practice and improve our understanding of the epidemiology and clinical and economic burden of CKD, as well as determinants of clinical outcomes and PROs from a range of geographical regions in a real-world CKD setting

Left/right asymmetric collective migration of parapineal cells is mediated by focal FGF signalling activity in leading cells

The ability of cells to collectively interpret surrounding environmental signals underpins their capacity to coordinate their migration in various contexts, including embryonic development and cancer metastasis. One tractable model for studying collective migration is the parapineal, a left-sided group of neurons that arises from bilaterally positioned precursors that undergo a collective migration to the left side of the brain. In zebrafish, the migration of these cells requires Fgf8 and, in this study, we resolve how FGF signaling correlates with—and impacts the migratory dynamics of—the parapineal cell collective. The temporal and spatial dynamics of an FGF reporter transgene reveal that FGF signaling is activated in only few parapineal cells usually located at the leading edge of the parapineal during its migration. Overexpressing a constitutively active Fgf receptor compromises parapineal migration in wild-type embryos, while it partially restores both parapineal migration and mosaic expression of the FGF reporter transgene in fgf8−/− mutant embryos. Focal activation of FGF signaling in few parapineal cells is sufficient to promote the migration of the whole parapineal collective. Finally, we show that asymmetric Nodal signaling contributes to the restriction and leftwards bias of FGF pathway activation. Our data indicate that the first overt morphological asymmetry in the zebrafish brain is promoted by FGF pathway activation in cells that lead the collective migration of the parapineal to the left. This study shows that cell-state differences in FGF signaling in front versus rear cells is required to promote migration in a model of FGF-dependent collective migration

Risk of cardiovascular events and death associated with initiation of SGLT2 inhibitors compared with DPP-4 inhibitors:an analysis from the CVD-REAL 2 multinational cohort study

Background Cardiovascular outcome trials have shown cardiovascular benefit with sodium-glucose co-transporter-2 (SGLT2) inhibitors in patients with type 2 diabetes, whereas dipeptidyl peptidase-4 (DPP-4) inhibitors have not shown an effect. We aimed to address knowledge gaps regarding the comparative effectiveness of SGLT2 inhibitor use in clinical practice (with DPP-4 inhibitor use as an active comparator) across a range of cardiovascular risks and in diverse geographical settings. Methods In this comparative cohort study, we used data from clinical practice from 13 countries in the Asia-Pacific, Middle East, European, and North American regions to assess the risk of cardiovascular events and death in adult patients with type 2 diabetes newly initiated on SGLT2 inhibitors compared with those newly initiated on DPP-4 inhibitors. De-identified health records were used to select patients who were initiated on these drug classes between Dec 1, 2012, and May 1, 2016, with follow-up until Dec 31, 2014, to Nov 30, 2017 (full range; dates varied by country). Non-parsimonious propensity scores for SGLT2 inhibitor initiation were developed for each country and patients who were initiated on an SGLT2 inhibitor were matched with those who were initiated on a DPP-4 inhibitor in a 1:1 ratio. Outcomes assessed were hospitalisation for heart failure, all-cause death, myocardial infarction, and stroke. Hazard ratios (HRs) were estimated by country and then pooled in a weighted meta-analysis. Findings Following propensity score matching, 193 124 new users of SGLT2 inhibitors and 193 124 new users of DPP-4 inhibitors were included in the study population. Participants had a mean age of 58 years (SD 12.2), 170 335 (44.1%) of 386 248 were women, and 111933 (30.1%) of 372 262 had established cardiovascular disease. Initiation of an SGLT2 inhibitor versus a DPP-4 inhibitor was associated with substantially lower risks of hospitalisation for heart failure (HR 0.69, 95% CI 0. 61-0. 77; p Interpretation In this large, international, observational study, initiation of SGLT2 inhibitors versus DPP-4 inhibitors was associated with lower risks of heart failure, death, myocardial infarction, and stroke, providing further support for the cardiovascular benefits associated with use of SGLT2 inhibitors in patients with type 2 diabetes. Copyright (C) 2020 Elsevier Ltd. All rights reserved