Biology subjects

Romero, N.

Publications and source records attributed to Romero, N..

10 recordsLinked to original sources

bioRxiv2026

Mafb-lineage activation of a short polyalanine (+5) PHOX2B mutation produces severe respiratory dysfunction with preserved postnatal weight gain among survivors in a mouse model of congenital central hypoventilation syndrome

Rationale: Congenital central hypoventilation syndrome (CCHS) is most commonly caused by polyalanine repeat mutations in PHOX2B. The in vivo consequences of the short five-alanine expansion and the contribution of specific hindbrain lineages to the resulting respiratory phenotype remain poorly understood. Objectives: To characterize the neonatal phenotype caused by the Phox2b25Ala/+ mutation and determine the contribution of the MafB lineage associated with the r5-r6 hindbrain territory. Methods: We generated a conditional Phox2b25Ala allele and studied mice with constitutive or MafB-lineage activation. Neonatal survival, growth, gastric milk content, ventilation, and hypercapnic responses were assessed in vivo. Respiratory-network activity and responses to extracellular acidification were recorded in E18.5 isolated brainstem-spinal cord preparations, and retrotrapezoid nucleus (RTN) development was examined histologically. Measurements and Main Results: Constitutive Phox2b25Ala/+ pups exhibited high neonatal mortality, markedly impaired weight gain, reduced gastric milk scores, hypoventilation, increased apnea time, and blunted ventilatory responses to CO2. Embryonic preparations showed a slower respiratory rhythm, an impaired response to acidification, and severe RTN dysgenesis. Activation of the mutant allele in the MafB lineage was also associated with severe respiratory dysfunction, RTN dysgenesis, and early neonatal mortality. In contrast, postnatal weight gain was preserved among surviving MafB-lineage mutants, and the reduction in gastric milk scores was significantly attenuated compared with constitutive mutants. Conclusions: A short PHOX2B polyalanine expansion reproduces major respiratory features of CCHS in mice. Activating the mutant allele in the MafB lineage is sufficient to cause severe respiratory dysfunction and neonatal mortality, whereas postnatal weight gain is preserved among survivors.

neuroscience↗

bioRxiv2026

Ryanodine receptor 1 ( RYR1 ) patient-derived muscle cells recapitulate disease phenotypes in 2D and 3D culture models

The Ryanodine Receptor 1 (RyR1) is the major Ca2+ release channel in skeletal muscle and plays a crucial role in excitation-contraction coupling. Pathogenic variants in RYR1 are the most common cause of congenital myopathy, for which there are no approved treatments. Patient-centric disease models may help to facilitate the design and screening of novel therapeutics in a human genomic context. In this report, we describe the differentiation of five dominant RYR1-related myopathy patient-derived induced pluripotent stem cell (iPSC) lines into muscle progenitor cells (MPCs), and subsequently into multinucleated myotubes in 2- and 3- Dimensional (D) culture models. In 2D, we show significantly reduced Ca2+ release in a patient line compared to a healthy control following stimulation with caffeine. In 3D engineered muscle tissues (EMTs), patient-relevant phenotypes including reduced twitch amplitude, delayed relaxation and altered force-frequency relationships were observed in a patient line compared to two healthy controls. We also show that the 2D cultures are a suitable platform for screening the efficacy and cellular toxicity of antisense oligonucleotide therapeutics. Together, these results suggest that iPSC-derived skeletal muscle cultures are useful models for understanding the pathobiology of RYR1-related myopathies and as a testbed for emerging treatments.

Cell Biology↗

bioRxiv2024

Oxygen carrying nanoemulsions and respiratory hyperoxia eliminate tumor hypoxia-induced suppression and improve cancer immunotherapy

Hypoxia-HIF-1-driven immunosuppressive transcription and cAMP-elevating signaling through A2A-adenosine receptors (A2AR) represent a major tumor-protecting pathway that enables immune evasion. Recent promising clinical outcomes due to the blockade of the adenosine-generating enzyme CD73 and A2AR in patients refractory to all other therapies have confirmed the importance of targeting hypoxia-adenosinergic signaling. We report a novel and feasible approach to target the upstream stage of hypoxia-adenosinergic immunosuppression using an oxygen-carrying nanoemulsion (perfluorocarbon blood substitute). It is shown that oxygenation agent therapy i) eliminates tumor hypoxia, ii) improves efficacy of endogenously developed and adoptively transferred T cells, and thereby iii) promotes regression of tumors in different anatomical locations. We show that both T cells and NK cells avoid hypoxic tumor areas and that reversal of hypoxia by oxygenation agent therapy increases intratumoral infiltration of activated T cells and NK cells due to re-programming of the tumor microenvironment (TME). Thus, repurposing oxygenation agents in combination with supplemental oxygen may improve current cancer immunotherapies by preventing hypoxia-adenosinergic suppression, promoting immune cell infiltration and enhancing effector responses. These data also suggest that pretreating patients with oxygenation agent therapy may reprogram the TME from immune-suppressive to immune-permissive prior to adoptive cell therapy, or other forms of immunotherapy. SummaryOxygen delivering nanoemulsions and respiratory hyperoxia address limitations of blood vessel-mediated tumor oxygenation and promote anti-tumor immune responses to enhance immunotherapy.

immunology↗

bioRxiv2023

Human light meromyosin mutations linked to skeletal myopathies disrupt the coiled coil structure and myosin head sequestration

Myosin heavy chains encoded by MYH7 and MYH2 are among the most abundant proteins in human skeletal muscle. After decades of intense research using a wide range of biophysical and biological approaches, their functions have begun to be elucidated. Despite this, it remains unclear how mutations in these genes and resultant proteins disrupt myosin structure and function, inducing pathological states and skeletal myopathies termed myosinopathies. Here, we have analysed the effects of several common MYH7 and MYH2 mutations located in light meromyosin (LMM) using a broad range of approaches. We determined the secondary structure and filament forming capabilities of expressed and purified LMM constructs in vitro, performed in-silico modelling of LMM constructs, and evaluated the incorporation of eGFP-myosin heavy chain constructs into sarcomeres in cultured myotubes. Using muscle biopsies from patients, we applied Mant-ATP chase protocols to estimate the proportion of myosin heads that were super-relaxed, X-ray diffraction measurements to estimate myosin head order and myofibre mechanics to investigate contractile function. We found that human MYH7 and MYH2 LMM mutations commonly disrupt myosin coiled-coil structure and packing of filaments in vitro; decrease the myosin super-relaxed state in vivo and increase the basal myosin ATP consumption; but are not associated with myofibre contractile deficits. Altogether, these findings indicate that the structural remodelling resulting from LMM mutations induces a pathogenic state in which formation of shutdown heads is impaired, thus increasing myosin head ATP demand in the filaments, rather than affecting contractility. These key findings will help in the design of future therapies for myosinopathies.

physiology↗

bioRxiv2022

Calculating ATP production rates from oxidative phosphorylation and glycolysis during cell activation

Oxidative phosphorylation and glycolysis are the dominant ATP-generating pathways in mammalian metabolism. The balance between these two pathways is often shifted to execute cell-specific functions in response to stimuli that promote activation, proliferation, or differentiation. However, measurement of these metabolic switches has remained mostly qualitative, making it difficult to discriminate between healthy, physiological changes in energy transduction or compensatory responses due to metabolic dysfunction. We therefore developed a broadly applicable method to calculate ATP production rates from oxidative phosphorylation and glycolysis using Seahorse XF Analyzer data. We quantified the bioenergetic changes observed during macrophage polarization as well as cancer cell adaptation to in vitro culture conditions. Additionally, we detected substantive changes in ATP utilization upon neuronal depolarization and T cell receptor activation that are not evident from steady-state ATP measurements. This method generates a single readout that allows the direct comparison of ATP produced from oxidative phosphorylation and glycolysis in live cells. Additionally, the manuscript provides a framework for tailoring the calculations to specific cell systems or experimental conditions.

biochemistry↗

bioRxiv2022

IMPatienT: an integrated web application to digitize, process and explore multimodal patient data.

Medical acts, such as imaging, lead to the production of several medical text report that describes the relevant findings. This induces multimodality in patient data by linking image data to free-text and consequently, multimodal data have become central to drive research and improve diagnosis. However, the exploitation of patient data is challenging as the ecosystem of analysis tools is fragmented depending on the type of data (images, text, genetics), the task (processing, exploration) and domains of interest (clinical phenotype, histology). To address the challenges, we present IMPatienT (Integrated digital Multimodal PATIENt daTa), a simple, flexible and open-source web application to digitize, process and explore multimodal patient data. IMPatienT has a modular architecture to: (i) create a standard vocabulary for a domain, (ii) digitize and process free-text data, (iii) annotate images and perform image segmentation, and (iv) generate a visualization dashboard and perform diagnosis suggestions. We showcased IMPatienT on a corpus of 40 simulated muscle biopsy reports of congenital myopathy patients. As IMPatienT relies on a user-designed vocabulary, it can be adapted to any domain of research and can be used as a patient registry for exploratory data analysis (EDA). A demo instance of the application is available at https://impatient.lbgi.fr/.

bioinformatics↗

bioRxiv2020

Type I Interferon acts as a major barrier to the establishment of infectious bursal disease virus (IBDV) persistent infections

Infectious bursal disease virus (IBDV), the best characterized member of the Birnaviridae family, is a highly relevant avian pathogen causing both acute and persistent infections in different avian hosts. Here, we describe the establishment of clonal, long-term, productive persistent IBDV infections in DF-1 chicken embryonic fibroblasts. Although virus yields in persistently-infected cells are exceedingly lower than those detected in acutely infected cells, the replication fitness of viruses isolated from persistently-infected cells is higher than that of the parental virus. Persistently-infected DF-1 and IBDV-cured cell lines derived from them do not respond to type I interferon (IFN). High-throughput genome sequencing revealed that this defect is due to mutations affecting the IFN/{beta} receptor subunit 2 (IFNAR2) gene resulting in the expression of IFNAR2 polypeptides harbouring large C-terminal deletions that abolish the signalling capacity of IFN/{beta} receptor complex. Ectopic expression of a recombinant chicken IFNAR2 gene efficiently rescues IFN responsiveness. IBDV-cured cell lines derived from persistently infected cells exhibit a drastically enhanced proneness to establishing new persistent IBDV infections. Additionally, experiments carried out with human HeLa cells lacking the IFNAR2 gene fully recapitulate results obtained with DF-1 cells, exhibiting a highly enhanced capacity to both survive the acute IBDV infection phase and to support the establishment of persistent IBDV infections. Results presented here show that the inactivation of the JAK-STAT signalling pathway significantly reduces the apoptotic response induced by the infection, hence facilitating the establishment and maintenance of IBDV persistent infections. IMPORTANCEMembers of the Birnaviridae family, including infectious bursal disease virus (IBDV), exhibit a dual behaviour, causing acute infections that are often followed by the establishment of life-long persistent asymptomatic infections. Indeed, persistently infected specimens might act as efficient virus reservoirs, hence potentially contributing to virus dissemination. Despite the key importance of this biological trait, information about mechanisms triggering IBDV persistency is negligible. Our report evidences the capacity of IBDV, a highly relevant avian pathogen, to establishing long-term, productive, persistent infections in both avian and human cell lines. Data presented here provide novel and direct evidence about the crucial role of type I IFNs on the fate of IBDV-infected cells and their contribution to controlling the establishment of IBDV persistent infections. The use of cell lines unable to respond to type I IFNs opens a promising venue to unveiling additional factors contributing to IBDV persistency.

microbiology↗

bioRxiv2020

Lamin-related congenital muscular dystrophy alters mechanical signaling and skeletal muscle growth

BackgroundLaminopathies are a clinically heterogeneous group of disorders caused by mutations in the LMNA gene, which encodes the nuclear envelope proteins lamins A and C. The most frequent diseases associated with LMNA mutations are characterized by skeletal and cardiac involvement, and include autosomal dominant Emery-Dreifuss muscular dystrophy (EDMD), limb-girdle muscular dystrophy type 1B, and LMNA-related congenital muscular dystrophy (LMNA-CMD). Although the exact pathophysiological mechanisms responsible for LMNA-CMD are not yet understood, severe contracture and muscle atrophy suggest that impair skeletal muscle growth may contribute to the disease severity. MethodsWe used human muscle stem cells (MuSCs) carrying 4 different LMNA mutations and two mouse models of muscle laminopathies, representing a spectrum of disease severity, to investigate the ability of skeletal muscle to differentiate and to hypertrophy in response to mechanical challenges. We extended these finding to individuals with LMNA-related muscular dystrophy using muscle biopsies. ResultsIn vitro, we observe impaired myogenic differentiation with disorganized cadherin/{beta} catenin adhesion complexes in MuSCs carrying LMNA-CMD. We show that skeletal muscle from Lmna-CMD mice is unable to hypertrophy in response to functional overload, due to defective accretion of activated MuSCs, defective protein synthesis and defective remodeling of the neuro-muscular junction. Moreover, stretched myotubes and overloaded muscle fibers with LMNA-CMD mutations display aberrant mechanical regulation of the Yes-Associated Protein (YAP), a key sensor and mediator of mechanical cues. We also observe defects in MuSC activation and YAP signaling in muscle biopsies from LMNA-CMD patients. These phenotypes are not recapitulated in closely-related EDMD models. ConclusionsCombining studies in vitro, in vivo and patient samples, we find that LMNA-CMD mutations interfere with mechano-signaling pathways in skeletal muscle, implicating defective skeletal muscle growth as a pathogenic contributor for the severity of LMNA-related muscular dystrophy.

physiology↗

bioRxiv2020

SH3KBP1 scaffolds endoplasmic reticulum and controls skeletal myofibers architecture and integrity

The building block of skeletal muscle is the multinucleated muscle fiber, formed by the fusion of hundreds of mononucleated precursor cells, myoblasts. In the normal course of muscle fiber development or regeneration, myonuclei are actively positioned throughout muscular development and adopt special localization in mature fibers: regular spacing along muscle fibers periphery, raising the notion of MyoNuclear Domains (MNDs). There is now growing support for a direct connection between myonuclear positioning and normal function of muscles, but how myonuclei affects muscle function remains poorly characterized. To identify new factors regulating forces applied on myonuclei in muscles fibers, we performed a siRNA screen and identified SH3KBP1 as a new factor controlling myonuclear positioning in early phases of myofibers formation. Depletion of SH3KBP1 induces a reset of MNDs establishment in mature fibers reflected by a dramatic reduction in pairwise distance between myonuclei. We show that SH3KBP1 scaffolds Endoplasmic Reticulum (ER) in myotubes that in turn controls myonuclei velocity and localization and thus myonuclear domains settings. Additionally, we show that in later phases of muscle maturation, SH3KBP1 contributes to the formation and maintenance of Sarcoplasmic Reticulum (SR) and Transverse-tubules (T-tubules). We also demonstrate that in muscle fibers, GTPase dynamin-2 (DNM2) binds to SH3 domains of SH3KBP1. Interestingly, we observed that Sh3kbp1 mRNA is up regulated in a mouse model harboring the most frequent mutation for Autosomal Dominant CentroNuclear Myopathy (AD-CNM): Dnm2+/R465W. SH3KBP1 thus appears as a compensation mechanism in this CNM model since its depletion contributes to an increase of CNM-like phenotypes (reduction of muscle fibers Cross-section Areas (CSA) and increase in slow fibers content). Altogether our results identify SH3KBP1 as a new regulator of myonuclear domains establishment in the early phase of muscle fibers formation through ER scaffolding and later in myofibers integrity through T-tubules scaffolding/maintenance. SummaryMyonuclei are actively positioned throughout muscular development. Guiraud, Christin, Couturier et al show that SH3KBP1 scaffolds the ER through Calnexin interaction and controls myonuclei motion during early steps of muscle fibers formation. Besides SH3KBP1 participates in cell fusion and T-tubules formation/maintenance in mature skeletal muscle fibers and contributes to slow-down CNM-like phenotypes.

cell biology↗

bioRxiv2019

PI3K activation prevents Aβ42-induced synapse loss and favors insoluble amyloid deposits formation

Alzheimers disease is, to a large extent, a disease of the synapse triggered by the unbalanced amyloidogenic cleavage of the amyloid precursor protein APP. Excess of A{beta}42 peptide in particular is considered a hallmark of the disease. Here we drive the expression of the human A{beta}42 peptide to assay the neuroprotective effects of PI3K in adult Drosophila melanogaster. We show that the neuronal expression of the human peptide elicits progressive toxicity in the adult. The pathological traits include reduced axonal transport, synapse loss, defective climbing ability and olfactory perception, as well as life-span reduction. The A{beta}42-dependent synapse decay does not involve transcriptional changes in the core synaptic protein encoding genes: bruchpilot, liprin and synaptobrevin. All toxicity features, however, are suppressed by the co-expression of PI3K. Moreover, PI3K activation induces a significant increase of 6E10 and Thioflavin-positive amyloid deposits. Mechanistically, we suggest that A{beta}42-Ser26 could be a candidate residue for direct or indirect phosphorylation by PI3K. Finally, along with these in vivo experiments we further analyze A{beta}42 toxicity and its suppression by PI3K activation in in vitro assays with SH-SY5Y human neuroblastoma cell cultures, where A{beta}42 aggregation into large insoluble deposits is reproduced. Taken together, these results uncover a potential novel pharmacological strategy against this disease with PI3K activation as a target.

neuroscience↗