A Yap-dependent mechanoregulatory program sustains cell migration for embryo axis assembly

The assembly of the embryo’s primary axis is a fundamental landmark for the establishment of the vertebrate body plan. Although the morphogenetic movements directing cell convergence towards the midline have been described extensively, little is known on how gastrulating cells interpret mechanical cues. Yap proteins are well-known transcriptional mechanotransducers, yet their role in gastrulation remains elusive. Here we show that the double knockout of yap and its paralog yap1b in medaka results in an axis assembly failure, due to reduced displacement and migratory persistence in mutant cells. Accordingly, we identified genes involved in cytoskeletal organization and cell-ECM adhesion as potentially direct Yap targets. Dynamic analysis of live sensors and downstream targets reveal that Yap is acting in migratory cells, promoting cortical actin and focal adhesions recruitment. Our results indicate that Yap coordinates a mechanoregulatory program to sustain intracellular tension and maintain the directed cell migration for embryo axis development

Mutation of vsx genes in zebrafish highlights the robustness of the retinal specification network

Genetic studies in human and mice have established a dual role for Vsx genes in retina development: an early function in progenitors' specification, and a later requirement for bipolar-cells fate determination. Despite their conserved expression patterns, it is currently unclear to which extent Vsx functions are also conserved across vertebrates, as mutant models are available only in mammals. To gain insight into vsx function in teleosts, we have generated vsx1 and vsx2 CRISPR/Cas9 double knockouts (vsxKO) in zebrafish. Our electrophysiological and histological analyses indicate severe visual impairment and bipolar cells depletion in vsxKO larvae, with retinal precursors being rerouted toward photoreceptor or Müller glia fates. Surprisingly, neural retina is properly specified and maintained in mutant embryos, which do not display microphthalmia. We show that although important cis-regulatory remodelling occurs in vsxKO retinas during early specification, this has little impact at a transcriptomic level. Our observations point to genetic redundancy as an important mechanism sustaining the integrity of the retinal specification network, and to Vsx genes regulatory weight varying substantially among vertebrate species

Impact of CoQ deficiency on embryonic development in zebrafish

Trabajo presentado en EMBO Workshop. Developmental metabolism: flows of energy, matter, and information, celebrado en Heidelberg (Alemania) del 12 al 15 de septiembre de 2023.Coenzyme Q (CoQ) is a redox-active lipid with a prominent role in the mitochondrial respiratory chain. CoQ is also involved in other redox processes being the electron acceptor for specific mitochondrial dehydrogenases. Primary CoQ deficiencies are rare mitochondrial conditions, biochemically characterised by a reduction in CoQ, caused by biallelic mutations in any of the -at least- 11 COQ genes participating in its biosynthesis. Remarkably, patients show a broad spectrum of clinical manifestations, severity, and age of onset, but a clear genotype-phenotype correlation is still lacking. We hypothesise that the disease unfolding due to defects in specific COQ genes could be different during development and would determine severity, the age of onset and the affected tissues. Modelling rare diseases is a promising approach to overcoming the lack of epidemiological studies. Danio rerio (zebrafish) is a convenient vertebrate model to study embryogenesis due to its straightforward genetic manipulation, the highly efficient, external and easy-to-control oocyte fertilisation and their transparent embryos that make them easy to monitor. We have generated a collection of CRISPR-Cas9 F0 knockout zebrafish models carrying a high rate of biallelic mutations in all known genes involved in CoQ biosynthesis. These somatic F0 mutants enable a high throughput evaluation of loss-of-function phenotypes during early development. Moreover, we have generated a stable coq6 zebrafish knockout line which will allow us to monitor the unfolding of the disease at later embryonic stages. Our work will contribute to close the gap between the knowledge of the regulation of CoQ biosynthesis during development and its coordination with mitochondrial biogenesis. The functional and physiological characterisation of our animal models will help to better understand CoQ deficiencies in humans.Peer reviewe

Interplay between Wnt and Yap signaling in the formation of the eye

Trabajo presentado en el 19th International Congress of Developmental Biology, celebrado en Guia (Portugal) del 16 al 20 de octubre de 2022

Yap directs cell migration required for axis condensation during gastrulation

Trabajo presentado en el EMBL Symposium: Mechanobiology in development and disease, celebrado en modalidad virtual del 15 al 18 de mayo de 2022

Yap directs cell migration required for axis condensation during gastrulation

Trabajo presentado en el 19th International Congress of Developmental Biology, celebrado en Guia (Portugal) del 16 al 20 de octubre de 2022

A Yap-dependent mechanoregulatory program sustains cell migration for embryo axis assembly

The assembly of the embryo’s primary axis is a fundamental landmark for the establishment of the vertebrate body plan. Although the morphogenetic movements directing cell convergence towards the midline have been described extensively, little is known on how gastrulating cells interpret mechanical cues. Yap proteins are well-known transcriptional mechanotransducers, yet their role in gastrulation remains elusive. Here we show that the double knockout of yap and its paralog yap1b in medaka results in an axis assembly failure, due to reduced displacement and migratory persistence in mutant cells. Accordingly, we identified genes involved in cytoskeletal organization and cell-ECM adhesion as potentially direct Yap targets. Dynamic analysis of live sensors and downstream targets reveal that Yap is acting in migratory cells, promoting cortical actin and focal adhesions recruitment. Our results indicate that Yap coordinates a mechanoregulatory program to sustain intracellular tension and maintain the directed cell migration for embryo axis development.This work was supported by grants awarded to JRMM from the Spanish Ministry of Science, Innovation, and Universities (AEI): (References, RED2018-102553-T, PID2020-112566GB-I00, and CEX2020-001088-M), and by the Marie SklodowskaCurie H2020-MSCA-IF- 2018-ST MechaPattern 834610 and La Caixa Junior Leader Incoming from Fundación “la Caixa” awarded to M.A.C.With funding from the Spanish government through the ‘Severo Ochoa Centre of Excellence’ accreditation (CEX2020-001088-M).Peer reviewe

Mutation of vsx genes in zebrafish highlights the robustness of the retinal specification network

Genetic studies in human and mice have established a dual role for Vsx genes in retina development: an early function in progenitors’ specification, and a later requirement for bipolar-cells fate determination. Despite their conserved expression patterns, it is currently unclear to which extent Vsx functions are also conserved across vertebrates, as mutant models are available only in mammals. To gain insight into vsx function in teleosts, we have generated vsx1 and vsx2 CRISPR/Cas9 double knockouts (vsxKO) in zebrafish. Our electrophysiological and histological analyses indicate severe visual impairment and bipolar cells depletion in vsxKO larvae, with retinal precursors being rerouted toward photoreceptor or Müller glia fates. Surprisingly, neural retina is properly specified and maintained in mutant embryos, which do not display microphthalmia. We show that although important cis-regulatory remodelling occurs in vsxKO retinas during early specification, this has little impact at a transcriptomic level. Our observations point to genetic redundancy as an important mechanism sustaining the integrity of the retinal specification network, and to Vsx genes regulatory weight varying substantially among vertebrate species