BACKGROUND: Fibrillins provide a scaffold for elastic fiber formation, which enables lung recoil and aortic compliance. Abnormal fibrillin microfibrils, as in Marfan syndrome, lead to enlarged alveoli, vascular stiffenin...BACKGROUND: Fibrillins provide a scaffold for elastic fiber formation, which enables lung recoil and aortic compliance. Abnormal fibrillin microfibrils, as in Marfan syndrome, lead to enlarged alveoli, vascular stiffening, and aneurysms. Our earlier studies suggested that fibrillin function depends on O-glucosylation of its epidermal growth factor (EGF)-like repeats by protein O-glucosyltransferase 2 (POGLUT2) and 3 (POGLUT3). Mice lacking both enzymes (Poglut2/3 DKO) die soon after birth. Rare survivors are runted, have digit 2-3 syndactyly, and variable eye defects. Here, we wanted to determine whether O-glucosylation was important for fibrillin organization/function during lung and aorta development. RESULTS: Fibrillin microfibrils and elastic fibrils were reduced and disorganized in the Poglut2/3 DKO lung and aorta. In the lung, loss of O-glucosylation impaired airway branching, delayed sacculation, and postnatally caused mildly enlarged alveolar airspaces and reduced lipofibroblasts and capillary endothelial cells. In the ascending aorta, the Poglut2/3 DKO led to disorganized smooth muscle layers with increased nuclear YAP, potentially indicating a change in matrix stiffness. CONCLUSIONS: The lung and aorta defects in Poglut2/3 DKO resembled mouse Fbn1 and Ltbp mutant models, suggesting a common microfibril-driven mechanism. Future studies should examine how loss of fibrillin O-glucosylation affects microfibril-dependent regulation of TGF-β and BMP signaling and matrix biomechanics.
BACKGROUND: Rubinstein Taybi syndrome (RSTS), a rare congenital disease, is caused by mutations in lysine acetyl transferase type 3 (KAT3) genes, EP300 and CREBBP. Many of the tissues affected in RSTS are derived from th...BACKGROUND: Rubinstein Taybi syndrome (RSTS), a rare congenital disease, is caused by mutations in lysine acetyl transferase type 3 (KAT3) genes, EP300 and CREBBP. Many of the tissues affected in RSTS are derived from the neural crest (NC). Hence, we proposed that NC development would be perturbed in RSTS. RESULTS: Zebrafish RSTS models generated by knocking down or mutating ep300a and crebbpa genes reveal defects in NC migration. This effect on migration is conserved in NC cells generated from human RSTS patient-derived induced pluripotent stem cells (iPSC) cells. The defects in NC migration can be partially reversed by HDAC inhibition in morphant embryos. KAT3 knockdown causes downregulation of snai1b and snai2 and upregulation of cdh6, important regulators of epithelial to mesenchymal transition (EMT). Snai2 is known to repress CDH6, also known as cadherin 6b, in chick NC cells facilitating their delamination from the neural tube and migration. CONCLUSIONS: We demonstrate for the first time that NC migration is defective in zebrafish and iPSC models of RSTS. We make a case for classifying RSTS as a neurocristopathy. We propose that KAT3 genes control NC migration through regulation of EMT genes snai2 and snai1b.
BACKGROUND: Elp1, a subunit of the Elongator complex, is essential for tRNA modification and neuronal development. Mutations in ELP1 underlie familial dysautonomia (FD), a disorder marked by sensory and autonomic neuropa...BACKGROUND: Elp1, a subunit of the Elongator complex, is essential for tRNA modification and neuronal development. Mutations in ELP1 underlie familial dysautonomia (FD), a disorder marked by sensory and autonomic neuropathy. While loss of Elp1 disrupts trigeminal ganglion formation and survival, the downstream molecular consequences remain poorly defined. RESULTS: We performed quantitative proteomic profiling of trigeminal ganglia from Elp1 conditional knockout (CKO) and control embryos at E13.5. Across 5650 detected proteins, 25 were significantly up-regulated and 26 down-regulated in Elp1 CKO embryos. EnrichR analysis revealed enrichment of up-regulated proteins in amino acid transport and tRNA aminoacylation pathways, with links to neuromuscular and neuropathic diseases. Down-regulated proteins were associated with RNA modification, cholesterol biosynthesis, and synaptic organization. Validation by immunohistochemistry confirmed decreased expression of the neurotrophic receptor Gfra3 and the neuropeptide Galanin, and increased levels of the chromatin regulator Chd1, in Elp1 CKO embryos relative to controls. CONCLUSIONS: These findings demonstrate that Elp1 loss disrupts metabolic, RNA modification, and neurotrophic signaling pathways in the developing trigeminal ganglion. Proteomic analysis thus provides new insight into the molecular consequences of Elp1 deficiency and highlights candidate mechanisms contributing to sensory neuron vulnerability in FD.
Neural crest cells are a transient embryonic population of cells that give rise to a wide range of structures, including craniofacial cartilage and bone, peripheral neurons and glia, as well as components of the cardiac...Neural crest cells are a transient embryonic population of cells that give rise to a wide range of structures, including craniofacial cartilage and bone, peripheral neurons and glia, as well as components of the cardiac outflow tract, among others. Proper formation, migration and differentiation of NCCs require tightly regulated secretion of signaling molecules, extracellular matrix components and membrane proteins, rendering NCCs particularly reliant on a highly efficient and precisely regulated secretory pathway. Disruption of this pathway has emerged as an important, yet underappreciated, mechanism underlying developmental disease. Mutations in genes encoding components of the secretory machinery have been linked to congenital disorders that affect neural crest-derived tissues, suggesting that impaired intracellular trafficking and cargo export can compromise NCC function. In this review, we propose that such disorders represent a distinct subclass of neurocristopathies, termed secretopathies, in which defects in secretory pathway drive neural crest-associated phenotypes. We further highlight TMED proteins as key cargo receptors within the early secretory pathway whose dysfunction may impact NCC secretory output. Recognizing secretopathies as a novel category of neurocristopathies provides a new framework for understanding the molecular basis of neural crest-related developmental disorders.
Myocyte enhancer factor 2C (MEF2C) is a critical transcription factor and plays a pivotal role in muscle development, cardiac reprogramming, cellular differentiation, and disease pathogenesis. In this review, we have sys...Myocyte enhancer factor 2C (MEF2C) is a critical transcription factor and plays a pivotal role in muscle development, cardiac reprogramming, cellular differentiation, and disease pathogenesis. In this review, we have systematically described the structural characteristics of the MEF2C protein, particularly its DNA-binding MADS-box and transcriptional regulatory domains, and outlined the multi-level regulation mechanism of its expression and activity. We further have highlighted the functional roles of MEF2C in heart and skeletal muscle development, including its involvement in cardiomyocyte differentiation and reprogramming, and its pathological implications in heart and skeletal muscle diseases. Finally, we have summarized the pathological implications of MEF2C in neurological disorders and tumorigenesis and underlined its role as a regulator in the body's inflammatory response, offering a theoretical foundation for understanding its physiological and pathological implications and for the development of therapeutic strategies targeting MEF2C-related diseases.
BACKGROUND: Most organisms on earth experience ultraviolet radiation. High levels of ultraviolet B radiation can cause DNA and protein damage. Zebrafish have become a popular model to investigate the impact of ultraviole...BACKGROUND: Most organisms on earth experience ultraviolet radiation. High levels of ultraviolet B radiation can cause DNA and protein damage. Zebrafish have become a popular model to investigate the impact of ultraviolet B radiation. Previous studies have identified that early ultraviolet B radiation damages the transient, larval fin fold by inducing apoptosis. However, until now it remained unknown how this early exposure affects late-forming skeletal structures. RESULTS: We determined that ultraviolet B radiation at early stages results in skeletal phenotypes appearing weeks later. Specifically, the dorsal fin skeleton fails to form following early larval exposure. Additionally, this early treatment results in disorganization of the late-forming anal fin and vertebral skeletal structures. We found that inbreeding sensitizes fish to this environmental perturbation, resulting in greater penetrance and expressivity of ultraviolet B radiation-induced phenotypes. These skeletal phenotypes were preceded by larval fin fold damage, precluding mesenchymal skeletal progenitor invasion, resulting in disruption of dorsal fin skeletal development. CONCLUSIONS: Ultraviolet B exposure early in zebrafish development variably damages the larval fin fold, resulting in variable loss of the adult dorsal fin skeleton, a structure that develops much later in life.
Sox8, Sox9, and Sox10 arose by multiple rounds of genome duplications from a single SoxE gene in ancestral vertebrates. In this review, we will briefly discuss the molecular structure and function of SoxE transcription f...Sox8, Sox9, and Sox10 arose by multiple rounds of genome duplications from a single SoxE gene in ancestral vertebrates. In this review, we will briefly discuss the molecular structure and function of SoxE transcription factors and their evolutionary origin. We will then discuss their expression, function, and developmental disorders. SoxE proteins play critical roles during the development of multiple tissues in vertebrate embryos, including the neural crest, inner ear, cartilages, and glia cells of diverse origins, heart, gonads, and gastrointestinal tract. Because they recognize the same DNA sequence, possess conserved functional domains, and have overlapping expression profiles, SoxE proteins act partly redundantly in many contexts. However, Sox8, Sox9, and Sox10 also have many unique and tissue-specific functions. In particular, Sox9 plays an essential role in chondrogenesis, whereas Sox10 is a central regulator of pigment and glia cells. The highly context-specific regulation of different sets of target genes by SoxE factors is due to their ability to interact and cooperate with many other proteins including other transcription factors, cofactors, and enzymes, which modulate their regulatory activity. The activity of SoxE proteins is also frequently altered in a context-dependent fashion by post-translational modifications such as phosphorylation, acetylation, and SUMOylation.
BACKGROUND: Starfish play essential ecological roles as predators and ecosystem regulators; however, detailed developmental descriptions exist for only a handful of species, none of which are from the Mediterranean Sea....BACKGROUND: Starfish play essential ecological roles as predators and ecosystem regulators; however, detailed developmental descriptions exist for only a handful of species, none of which are from the Mediterranean Sea. RESULTS: In this study, we provide the first full account of the development of the Mediterranean starfish Hacelia attenuata, from oocyte maturation through embryogenesis and larval formation, showing that its development largely follows the canonical pattern known from other asteroids. Oocytes resume meiosis when exposed to 1-methyladenine, exhibiting conserved features such as the formation of a nuclear actin shell for chromosome gathering prior to meiotic spindle assembly. Embryogenesis then proceeds through radial cleavages to form a ciliated blastula, followed by gastrulation via invagination and mesenchymal cell delamination. The larvae develop through typical bipinnaria and brachiolaria stages, displaying characteristic feeding structures and attachment organs. Importantly, developmental rate decreases substantially at lower temperatures, consistent with the species distribution in warm Mediterranean waters. CONCLUSIONS: Taken together, these findings position H. attenuata as a promising new model for studying thermal adaptation, environmental resilience, and conserved developmental mechanisms in starfish.
BACKGROUND: Ambystoma mexicanum is renowned for its extraordinary regenerative capacity. Regardless of whether progenitor cells arise via dedifferentiation or stem cell activation, these cells must replicate DNA to proli...BACKGROUND: Ambystoma mexicanum is renowned for its extraordinary regenerative capacity. Regardless of whether progenitor cells arise via dedifferentiation or stem cell activation, these cells must replicate DNA to proliferate before they ultimately differentiate. This rapid cell division increases the likelihood of DNA damage, requiring efficient repair mechanisms. RESULTS: We focused on the non-homologous end joining pathway, responsible for repairing double-strand DNA breaks, and investigated the effects of 2 key components-KU70/80 and LIGIV- using chemical inhibitors STL127705 and SCR130, respectively. We assessed the impact of these inhibitors on axolotl limb regeneration, finding that treatment with the LIGIV inhibitor (SCR130) led to a positive growth trend in the regenerated area. Histological analysis of re-amputated limbs revealed no major morphological differences between treated and control animals. However, we observed a significant increase in the number of senescent cells in the regenerated tissue after KU70/80 inhibition (STL127705) at 32 days post-amputation, suggesting that DNA repair inhibition may promote senescence. Furthermore, we detected a dose-dependent increase in DNA damage, indicated by the γH2AX(Ser139) signal, specifically in cells' nuclei within the regenerated tissues. CONCLUSIONS: These findings suggest that DNA repair inhibition impacts regeneration, potentially through mechanisms linked to cellular senescence and DNA damage accumulation.
BACKGROUND: The promoters and enhancers of heat shock genes, such as the 1.5-kb promoter of the zebrafish hsp70l gene, are valuable tools for temporal activation of transgenes. It has been widely purported that heat shoc...BACKGROUND: The promoters and enhancers of heat shock genes, such as the 1.5-kb promoter of the zebrafish hsp70l gene, are valuable tools for temporal activation of transgenes. It has been widely purported that heat shock treatments result in ubiquitous expression of hsp70l-driven transgenes. However, variations in expression levels of transgenes are observable in many studies, making it necessary to further characterize the transcriptional activity of the hsp70l promoter. RESULTS: Here, we report that the transgenic expression pattern of hsp70l-driven EGFP-LacR (a cell nucleus-localizing fusion protein of EGFP and Lac repressor) demonstrates explicitly that the hsp70l promoter is activated by heat shock in a mosaic fashion in 50-80% of embryonic cells and at even lower rates in postmitotic retinal cells in larvae. This mosaic expression is influenced by cell-cycle states and cell-type specificity. The expression rates at early embryonic stages can be increased by multiple heat shocks or cell cycle synchronization. CONCLUSION: The mosaic activation of the hsp70l promoter does not disqualify it as a powerful temporal gene activation tool. Mosaic activation can be used as an advantage for contexts where a transgene functions cell-autonomously; however, caution and proper controls are necessary to interpret gene functions in contexts where a transgene acts non-cell-autonomously.
BACKGROUND: The notochord is a midline structure essential for vertebrate embryogenesis, contributing to the development of the nervous system, digestive tract, and vertebral column. In particular, notochord signaling is...BACKGROUND: The notochord is a midline structure essential for vertebrate embryogenesis, contributing to the development of the nervous system, digestive tract, and vertebral column. In particular, notochord signaling is indispensable for proper patterning and coordinated development of alternating vertebrae and intervertebral discs (IVDs). Later, notochordal cells (NCs) mature and adopt a characteristic vacuolated morphology before giving rise to the core of the forming IVD, the nucleus pulposus (NP). Postnatally, NCs play a pivotal role in maintaining disc integrity through the secretion of specific factors and extracellular matrix (ECM). Despite its importance in disc formation and homeostasis, the morphogenetic mechanisms underlying the notochord's transformation into the NP are insufficiently characterized. RESULTS: We conducted a comprehensive histological and immunohistochemical analysis to investigate the cellular events governing NP formation in the mouse developing spine. Temporal analysis of intracytoplasmic vacuole formation using Lamp-1 marker revealed that vacuolation contributed to NP growth, while cell density progressively decreased. In addition, quantitative analyses demonstrated a notable proliferative capacity within notochordal cells coupled with region-specific apoptotic activity in sclerotome, at future disc sites. CONCLUSIONS: This study highlights the intricate balance of cellular proliferation, programmed cell death, matrix remodeling, and vacuolation dynamics as key determinants in shaping the NP along the rostro-caudal axis.
The arthropod head problem has been puzzling scientists for more than a century. Key to this conceptual dispute is the question if the anterior of the arthropod head is serially homologous with the rest of the arthropod...The arthropod head problem has been puzzling scientists for more than a century. Key to this conceptual dispute is the question if the anterior of the arthropod head is serially homologous with the rest of the arthropod body, is unsegmented, or is built of non-homologous segments. Recent work revived the latter hypothesis which would, if taken for true, provide a simple solution to most aspects of the arthropod head problem, thus being of significant importance for our understanding of structural homology and arthropod evolution. One of the key arguments supporting this hypothesis is that the segment-polarity gene (SPG) network is highly conserved in posterior segments, but varies significantly in anterior head segments. Defining the SPG network as a character-identity network (CHiN) for the arthropod segment, the anterior variability would strongly indicate a different origin of the anterior versus the posterior head segments in arthropods. Here I discuss the arthropod head problem with respect to the proposed CHiN. I come to the conclusion that careful literature analysis shows that the SPG network is more flexible than claimed, in both anterior and posterior segments, and that the CHiN argument is therefore not supporting the so-called "Non-Homology-Hypothesis."
The Japanese medaka, Oryzias latipes, has become an important vertebrate model organism for addressing research questions across a broad range of disciplines, including developmental and evolutionary biology, stem cells,...The Japanese medaka, Oryzias latipes, has become an important vertebrate model organism for addressing research questions across a broad range of disciplines, including developmental and evolutionary biology, stem cells, gene-environment interactions, behavioral neuroscience, disease modeling, and drug discovery. The medaka community took advantage of the successful completion of the ERC Synergy Grant project IndiGene to gather once again in the beautiful Heidelberg (July 22-25, 2025). Building on the opportunities created by the IndiGene project, which leverages the medaka inbreed panel Medaka Inbred Kiyosu-Karlsruhe as a unique resource for dissecting complex phenotype-genotype relationships, the meeting offered an outstanding update on emerging concepts, technologies, and community resources. By summarizing the content of each session, this report provides an overview of a vibrant and highly productive event that highlights the continued growth and vitality of medaka research.
Facial morphogenesis relies on the coordinated regulation of cellular behaviors that sculpt the face from simple facial prominences to the fully confluent lip and nose. Disruptions to migration of cranial neural crest ce...Facial morphogenesis relies on the coordinated regulation of cellular behaviors that sculpt the face from simple facial prominences to the fully confluent lip and nose. Disruptions to migration of cranial neural crest cells and/or the directed growth of the prominences will lead to abnormalities such as orofacial clefts. Here we review what is known about the roles of the actin cytoskeleton and its key regulators, the small RHO GTPases, during neural crest cell migration and facial development. Although small RHO GTPase signaling has been studied in the context of cancer and vascular pathologies, their role in facial development has received limited attention. In this review, we review the experimental data that connects changes in the function of small Rho GTPases to cytoskeletal dynamics and ultimately to facial morphogenesis. We also highlight human craniofacial disorders resulting from germline or somatic variants of small Rho GTPase pathway genes as well as associations between variants in GTPase-activating proteins (GAPs) and guanidine nucleotide exchange factors (GEFs) and the complex trait, non-syndromic cleft lip with or without cleft palate. The review points to a model where the gain or loss of RHO GTPase pathway components could be centrally involved in many craniofacial disorders and that the Rho GTPases are major regulators of homeostasis during normal development.
Kircher BK, Weberling A, Vance EJ
… +10 more, Shylo NA, Starr K, Griffin ZB, Wilson H, McClain M, Hollfelder F, Williams SA, Sanger TJ, Behringer RR, Trainor PA
BACKGROUND: The brown anole is a model species of the genus Anolis, a squamate (encompassing lizards and snakes) group widely studied in evolutionary, behavioral, and developmental biology. Full genome annotation, the es...BACKGROUND: The brown anole is a model species of the genus Anolis, a squamate (encompassing lizards and snakes) group widely studied in evolutionary, behavioral, and developmental biology. Full genome annotation, the establishment of gene editing techniques, and comprehensive description of reproductive tract morphology and embryogenesis in this species have laid the foundation for functional studies. However, analysis of brown anole oogenesis is still required and vital to optimize genome modification, mutant line establishment, and analyses of the evolution of reproductive developmental mechanisms. RESULTS: Here, we characterize ovary morphology and gametogenesis in the female brown anole, Anolis sagrei, using brightfield imaging, microCT, histology staining, electron microscopy, and confocal imaging. We define 10 stages of oocyte maturation, which commences inside the oogonial nest within the germinal bed and concludes with the mature follicle ready to ovulate based on follicle size, yolk acquisition, and follicular, cellular, and basement membrane architecture. CONCLUSIONS: We describe the complete oogenesis of the brown anole in 10 stages and report that oogenesis is highly conserved within iguanians, a suborder of lizards. With our staging framework, we lay the foundation for functional studies of oogenesis and optimized gene-editing.
BACKGROUND: Many maternal mRNAs in Drosophila primordial germ cells (PGCs) are degraded in concert with the synthesis of new transcripts from the zygotic genome during gastrulation and germ band elongation (3-5 h after e...BACKGROUND: Many maternal mRNAs in Drosophila primordial germ cells (PGCs) are degraded in concert with the synthesis of new transcripts from the zygotic genome during gastrulation and germ band elongation (3-5 h after egg laying [AEL]). However, few studies have focused on maternal mRNA destabilization in PGCs at the blastoderm stage that is prior to zygotic genome activation (ZGA). Thus, the stability of maternal mRNAs at this stage and regulation of their degradation remain poorly understood. To address this gap, we examined the role of Nanos, an RNA-binding protein known to promote mRNA degradation, in blastoderm-stage PGCs. RESULTS: By combining flow cytometry and RNA-sequencing (RNA-seq) analysis of PGCs, we identified the transcripts of 898 genes that were increased in nanos PGCs. Among them, 298 genes encode maternal transcripts that were downregulated by Nanos in PGCs. CONCLUSIONS: Our results show that Nanos downregulates maternal mRNA expression in PGCs before ZGA in Drosophila. As Nanos in C. elegans PGCs has also been reported to promote maternal-to-zygotic transition (MZT) via maternal mRNA downregulation during a transcriptionally silent state, our findings highlight the importance of investigating the function of Nanos for understanding the MZT in PGCs across various animal species.
BACKGROUND: Endocytosis constitutes a fundamental cellular process governing development through coordinated regulation of plasma membrane remodeling and ciliogenesis, processes essential for cell shape changes and tissu...BACKGROUND: Endocytosis constitutes a fundamental cellular process governing development through coordinated regulation of plasma membrane remodeling and ciliogenesis, processes essential for cell shape changes and tissue development. Although Twist1 null embryos display complete cranial neural tube (NT) closure defects and conditional knockout in neuroectoderm disrupts cranial neural crest cell fate determination and delamination, the function of TWIST1 in NT morphogenesis remains unknown. We investigated the basis underlying neuroectodermal morphological abnormalities in TWIST1 mutant embryos, specifically the formation of ectopic lateral bending points and cellular disorganization, by examining Twist1's role in cilia formation, adherens junction integrity, and endocytic vesicle dynamics. RESULTS: Immunofluorescence analysis revealed that cytosolic TWIST1 colocalizes with β-catenin and endocytic regulators LRP2 and RAB11B along the apical surface of cranial neuroectoderm. Twist1 knockout resulted in reduced ciliary length and number. Quantitative polymerase chain reaction (PCR) and Western blot analyses demonstrated upregulation of RAB11B and β-catenin at mRNA and protein levels in Twist1 mutants. This molecular dysregulation coincided with increased accumulation of apical endocytic vesicles and altered expression profiles of endocytic component genes, ultimately modifying the apical neuroectodermal cell-cell junctions. CONCLUSION: Our findings establish TWIST1 as a crucial factor for neuroectodermal morphology, demonstrating its importance in ciliogenesis, endocytic vesicle dynamics, and cell-cell integrity.