Biology subjects

Ruggiero, F.

Publications and source records attributed to Ruggiero, F..

7 recordsLinked to original sources

bioRxiv2026

Rewiring Fibroblast-Muscle Axis Drives Progressive Pathology in Bethlem Myopathy

Collagen VI-related myopathies, including Bethlem myopathy (BM), are progressive muscle disorders, but the mechanisms driving age-dependent disease progression remain poorly understood. Here, we used a zebrafish BM model carrying an exon-skipping mutation that generates a shorter collagen VI 1 chain and disrupts supramolecular assembly, recapitulating key features of the human disease. We further demonstrated that this model reproduces disease progression, with worsening muscle wasting, increased myofiber size variability, and age-associated skeletal deformities consistent with secondary consequences of muscle dysfunction rather than intrinsic bone defects. Single-nucleus RNA sequencing of trunk skeletal muscle revealed an early shift in cellular composition, with reduced myonuclei and increased fibroblast abundance, indicative of disease-associated aging. Myonuclei activated stress and quality control pathways, including autophagy and mitophagy, along with metabolic rewiring. In contrast, fibroblasts displayed early translational activation followed by progressive proteostatic and endoplasmic reticulum stress. At later stages, fibroblasts adopted a pro-fibrotic state, driving extracellular matrix remodeling and enhanced muscle-fibroblast communication. Consistently, analyses at the protein level confirmed early intracellular retention of the mutant protein, along with increased extracellular matrix deposition and fibrotic tissue formation in BM muscle. Among the three tested drugs targeting ER-stress and protein degradation, only TUDCA significantly ameliorated collagen VI deposition in the extracellular space in larvae. These findings identify fibroblasts as key drivers of disease progression and potential therapeutic targets.

developmental biology↗

bioRxiv2025

Col6 deficiency in a zebrafish model of Bethlem myopathy leads to dysfunction of the muscle dihydropyridine receptor

Bethlem myopathy (BM) results from mutations in genes encoding one of the three chains of collagen VI (ColVI). This muscle disease is characterized by skeletal muscle weakness and wasting worsening with age. How alteration in ColVI present outside muscle fibers in the extracellular matrix induces dysfunction within muscle fibers is still misunderstood. Here we explored intracellular Ca2+ handling properties in isolated fast skeletal muscle fibers from adult zebrafish harboring a mutation (col6a1{Delta}ex14) that is the most frequently found in BM patients. Col6a1{Delta}ex14 fish muscle exhibited progressive loss of ColVI deposition, defects in basement membrane and ColVI intracellular accumulation. By combining voltage-clamp and intracellular Ca2+ measurements on isolated fibers, we showed that voltage-dependence of intramembrane charge movements produced by the activation of CaV1.1 controlling sarcoplasmic reticulum (SR) Ca2+ release and voltage-dependence of depolarization-induced SR Ca2+ release were shifted toward negative potentials in col6a1{Delta}ex14 fish. These changes in voltage-dependence gave rise to larger SR Ca2+ leak at voltages close to resting values and to higher frequency of spontaneous SR Ca2+ release elementary events in mutant fish. Trunk muscle force and swimming performance were also found to be reduced in col6a1{Delta}ex14 fish and mis-localization of CaV1.1 subunits clusters was observed in mutant fibers t-tubules. These data indicate that ColVI deficiency in BM leads to CaV1.1 dysfunction that contributes to promote a pathogenic SR Ca2+ leak responsible for progressive muscle weakness and wasting. CaV1.1 could represent the still elusive transmembrane link allowing altered myomatrix to transduce pathogenic signals within muscle.

pathology↗

bioRxiv2025

Cranial suture integrity is maintained by Fgfr3 in zebrafish

Cranial suture formation is a dynamic process requiring precise cellular and molecular coordination to regulate bone growth and suture homeostasis. Despite the recognized role of Fibroblast Growth Factor Receptor 3 (FGFR3) in this process and its association with Muenke syndrome, one of the most common syndromic craniosynostoses, its precise function remains undefined. Through analyses of cranial suture formation and maintenance in a fgfr3 LoF zebrafish model displaying abnormal suture morphology, we demonstrate for the first time that Fgfr3 plays a pleiotropic role during these events. Transmission electron microscopy and second harmonic generation imaging revealed that Fgfr3 is involved in the proper organization of the collagen network within the suture. By employing specific transgenic reporter lines and studying gene expression of suture mesenchymal stem cell markers via RNAscope in situ hybridization, we show that Fgfr3 is crucial for regulating osteogenesis within the suture. Specifically, Fgfr3 limits the number of osteoprogenitors at the osteogenic front and promotes osteoblast maturation at the suture edge. Finally, our results reveal that Fgfr3-mediated regulation of osteogenesis involves cross-talk between FGF, canonical Wnt, and potentially BMP signaling pathways. In conclusion, these data position Fgfr3 as a central regulator of cranial suture formation and open new perspectives for understanding suture homeostasis and FGFR3-related craniosynostoses.

developmental biology↗

bioRxiv2024

Defining a Muscle Stem Cell matrisome signature: from transcriptome data to extracellular matrix niche topology.

Although intensively investigated, the regulation of skeletal muscle stem cells (MuSCs) by their niche remains an open question. The extracellular matrix (ECM) components of the niche represent a dynamic microenvironment that undoubtedly participates in MuSCs behavior. We used bioinformatics analysis of transcriptomic data to define the matrisome profile of skeletal muscle resident cells, comprising genes encoding ECM and ECM-associated proteins. We identified quiescent MuSCs as key ECM producers of the niche, notably through the expression of specific basement membrane genes as Col19a1 and Lama3 and regulators of ECM assembly, Thsd4 and Aebp1. Unexpectedly, quiescent MuSCs also expressed matrisome neurogenesis-related genes. Immunofluorescence staining of selected ECM components showed their organization in isolated murine myofiber bundles. Upon activation, MuSCs strikingly downregulated the niche-related ECM genes and instead expressed genes involved in basement membrane disruption and matrisome genes linked to cell motility. This study identified distinct matrisome signatures of quiescent and activated MuSCs that are consistent with their function in homeostasis and repair of damaged skeletal muscle.

cell biology↗

bioRxiv2023

Dual-topology of collagen XV and tenascin C acts in concert to guide and shape developing motor axons

During development, motor axons are guided towards their muscle target by various extrinsic cues including extracellular matrix (ECM) proteins those identities remain poorly documented. Using single-cell RNA-sequencing of differentiating slow muscle progenitors (SMP) in zebrafish, we charaterized the SMP as a major source of ECM proteins that were computationally predicted to form a basement membrane-like structure tailored for motor axon guidance. Multiple in vivo and in vitro approaches further revealed that motor axon shape and growth relies on the timely expression of the attractive cue Collagen XV-B (ColXV-B) that locally provides motor axons with a permissive soft microenvironment and separately organizes the repulsive cue Tenascin C into a unique functional dual topology. Bioprinted micropatterns mimicking their unique topology provide compelling evidence that it represents a sufficient condition to elicit directional motor axon growth. Our study provides the first evidence that ECM topology and stiffness critically influence motor axon navigation in vertebrates with potential applications in regenerative medicine for peripheral nerve injury.

developmental biology↗

bioRxiv2021

The myotendinous junction marker collagen XXII enables zebrafish postural control learning and optimal swimming performance through its force transmission activity

Although the myotendinous junction (MTJ) is essential for skeletal muscle integrity, its contribution to skeletal muscle function remains largely unknown. Here, we show that CRISPR-Cas9-mediated gene ablation of the MTJ marker col22a1 in zebrafish identifies two distinctive phenotypic classes: class 1 individuals reach adulthood with no overt muscle phenotype while class 2 display severe movement impairment and eventually dye before metamorphosis. Yet mutants that are unequally affected are all found to display defective force transmission attributed to a loss of ultrastructural integrity of the MTJ and myosepta, though with distinct degrees of severity. The behavior-related consequences of the resulting muscle weakness similarly reveal variable phenotypic expressivity. Movement impairment at the critical stage of swimming postural learning eventually causes class 2 larval death by compromising food intake while intensive exercise is required to uncover a decline in muscle performance in class 1 adults. By confronting MTJ gene expression compensation and structural, functional and behavioral insights of MTJ dysfunction, our work unravels variable expressivity of col22a1 mutant phenotype. This study also underscores COL22A1 as a candidate gene for myopathies associated with dysfunctional force transmission and anticipates a phenotypically heterogeneous disease.

developmental biology↗

bioRxiv2020

Papillary And Reticular Fibroblasts Generate Distinct Microenvironments That Differentially Impact Angiogenesis

Papillary and reticular dermis show distinct extracellular matrix (ECM) and vascularization, and fibroblasts isolated from these compartments have different gene expression patterns and behaviour in vitro. However, due to lack of relevant models, the contribution of skin fibroblast sub-populations to vascularization remains unknown. We thus cultured human papillary and reticular fibroblasts as cell sheets. Differential transcriptomic analysis was performed by RNA sequencing to characterize their microenvironment. Bioinformatic analysis revealed that each fibroblast population expressed specific angiogenesis and matrisome gene expression signatures resulting in specific ECM that differed both in composition and structure. The impact of secreted and ECM-bound factors was then assessed using 3D angiogenesis assays. When co-cultivated with endothelial cells, the papillary and reticular microenvironments induced the formation of distinct capillary networks mimicking the characteristics of vasculature of native dermis subcompartments (vessel diameter and density, number of branch points). Whereas conditioned media of papillary fibroblasts displayed intrinsic high angiogenic potential, reticular ones only contributed to capillary formation induced by exogenous VEGF. These results show that skin fibroblast populations regulate angiogenesis via both secreted and ECM-bound factors. Our work emphasizes the importance of papillary and reticular fibroblasts, not only for modelling dermis microenvironment but also for its vascularization.

cell biology↗