Biology subjects

Zilhao, R.

Publications and source records attributed to Zilhao, R..

3 recordsLinked to original sources

bioRxiv2024

Deregulation of multiple mechanisms shapes the onset of LAMA2-congenital muscular dystrophy

LAMA2-congenital muscular dystrophy (LAMA2-CMD) is the most common congenital muscular dystrophy. This often-lethal disease is triggered by mutations in LAMA2, coding for laminin-2 chain, a key extracellular matrix (ECM) component, prevalent in the skeletal muscle. Several phenotypes have been associated with LAMA2-CMD, however, it is not yet known what mechanisms are faulty, right at disease onset in utero. Using the dyW mouse model of LAMA2-CMD we showed that the disease onset is characterized by a profound downregulation of gene expression, with a marked effect on cytoskeletal organization, myoblast differentiation and fusion and altered DNA repair and oxidative stress responses. Concordantly, we found that Lama2-deficient myoblast cells displayed proliferation and differentiation defects, increased oxidative stress and DNA damage. Together, our findings provide unique insights into the processes dependent on laminin-2 chain during muscle development, revealing its critical importance to maintain muscle cell homeostasis already at fetal stages.

developmental biology↗

bioRxiv2020

A combined characterization of coelomic fluid cell types in the spiny starfish Marthasterias glacialis: inputs from flow cytometry and imaging

Coelomocytes is a generic name for a collection of cellular morphotypes, present in many coelomate animals, that has been reported as highly variable across echinoderm classes. The roles attributed to the major types of the free circulating cells present in the coelomic fluid of echinoderms include immune response, phagocytic digestion and clotting. The main aim of the present study is the thorough characterization of coelomocytes present in the coelomic fluid of Marthasterias glacialis (class Asteroidea) through the combined use of flow cytometry (FC) and fluorescence plus transmission electron microscopy. Two coelomocyte populations (here named P1 and P2) were identified by flow cytometry and subsequently studied in terms of abundance, morphology, ultrastructure, cell viability and cell cycle profiles. Ultrastructurally, P2 diploid cells showed two main morphotypes, similar to phagocytes and vertebrate thrombocytes, whereas the small P1 haploid cellular population was characterized by a low mitotic activity, relatively undifferentiated cytotype and a high nucleus/cytoplasm ratio. These last cells resemble stem-cell types present in other animals. P1 and P2 cells differ also in cell viability and cell cycle profiles. Additionally, two other morphotypes were only detected by fluorescence microscopy and a third one when using a combined microscopy/FC approach.

cell biology↗

bioRxiv2018

A protein phosphorylation module patterns the Bacillus subtilis spore outer coat

Assembly of the Bacillus subtilis spore coat involves over 80 protein components, which self-organize into a basal layer, a lamellar inner coat, a striated electrondense outer coat and a more external crust. CotB is an abundant component of the outer coat. Its C-terminal moiety contains a region, termed SKRB, formed by a series of serine-rich repeats, which we show is phosphorylated by the coat-associated Ser/Thr kinase CotH at multiple Ser residues. Another coat protein, CotG, which contains a central repeat region, SKRG, interacts with the C-terminal moiety of CotB and promotes its phosphorylation by CotH in vivo and in a heterologous system. CotG itself is phosphorylated by CotH but phosphorylation is enhanced in the absence of CotB. Spores of a cotHD288A strain, producing an inactive form of the kinase, like those formed by a cotG deletion mutant, lack the characteristic pattern of electrondense outer coat striations, while retaining the crust. Specifically, in the absence of CotG or CotH activity, most of the outer coat proteins are assembled but form a layer of amorphous material that peels-off the spore if crust formation is genetically ablated. In contrast, deletion of the SKRB region, has no major impact on the structure of the outer coat. Thus, phosphorylation of CotG by CotH is the principal factor establishing the structural pattern of the spore outer coat. The presence of the cotB/cotH/cotG cluster in several species closely related to B. subtilis and of cotG-like proteins in nearly all spore-formers that also code for a CotH homologue hints at the importance of this protein phosphorylation module in the morphogenesis of the spore outer layers.

microbiology↗