Biology subjects

Scott, I. C.

Publications and source records attributed to Scott, I. C..

9 recordsLinked to original sources

bioRxiv2025

Role of the obligate STRIPAK complex component Mob4 in zebrafish vascular development and stability

The STRiatin Interacting Phosphatases and Kinases (STRIPAK) complex is a conserved multiprotein module with functions in cell proliferation, cell growth, and cancer. Primarily examined through proteomic and in vitro studies, there is a relative lack of insight into the in vivo function of the STRIPAK complex during development. Motivated by the prominent interaction of STRIPAK and the CCM3 adapter protein, which is associated with the vascular disease cerebral cavernous malformation (CCM), we sought to examine the role of the conserved STRIPAK component Mob4 in early zebrafish vascular development. We use proximity-dependent biotinylation (BioID) coupled with mass spectrometry to show that Mob4 is a component of the STRIPAK complex in zebrafish. Loss of mob4 leads to pronounced cardiovascular and neuronal defects, including a leaky cerebral vasculature, hypersprouting of venous endothelial cells and poor neuronal branching. Conditional transgenic models further demonstrate a continuous and broad requirement for Mob4 in development. Taken together, these results suggest a key role for STRIPAK function in vascular development and stability, replicating hallmarks of CCM.

developmental biology↗

bioRxiv2025

Where is the melody? Spontaneous attention orchestrates melody formation during polyphonic music listening

Humans seamlessly process multi-voice music into a coherent perceptual whole. Yet the neural strategies supporting this experience remain unclear. One fundamental component of this process is the formation of melody, a core structural element of music. Previous work on monophonic listening has provided strong evidence for the neurophysiological basis of melody processing, for example indicating predictive processing as a foundational mechanism underlying melody encoding. However, considerable uncertainty remains about how melodies are formed during polyphonic music listening, as existing theories (e.g., divided attention, figure-ground model, stream integration) fail to unify the full range of empirical findings. Here, we combined behavioural measures with non-invasive electroencephalography (EEG) to probe spontaneous attentional bias and melodic expectation while participants listened to two-voice classical excerpts. Our uninstructed listening paradigm eliminated a major experimental constraint, creating a more ecologically valid setting. We found that attention bias was significantly influenced by both the high-voice superiority effect and intrinsic melodic statistics. We then employed transformer-based models to generate next-note expectation profiles and test competing theories of polyphonic perception. Drawing on our findings, we propose a weighted-integration framework in which attentional bias calibrates the overall degree of integration of the competing streams. In doing so, the proposed framework reconciles previous divergent accounts by showing that, even under free-listening conditions, melodies emerge through an attention-guided statistical integration mechanism. HighlightsO_LIEEG can be used to decode spontaneous attention during the uninstructed listening of polyphonic music. C_LIO_LIBehavioural and neural data indicate that spontaneous attention is influenced by both high-voice superiority and melodic contour. C_LIO_LIAttention bias impacts the neural encoding of the polyphonic streams, with strongest effects within 200 ms after note onset. C_LIO_LIStimuli that produced a stronger attention bias aligned with monophonic-model expectations, whereas stimuli with a weaker bias aligned with the Stream-Integration model. C_LIO_LIWe propose a bi-directional influence between attention and prediction mechanisms, with horizontal statistics impacting attention (i.e., salience), and attention impacting melody extraction. C_LI

neuroscience↗

bioRxiv2023

Tozorakimab (MEDI3506): a dual-pharmacology anti-IL-33 antibody that inhibits IL-33 signalling via ST2 and RAGE/EGFR to reduce inflammation and epithelial dysfunction

Interleukin (IL)-33 is a broad-acting alarmin cytokine that can drive inflammatory responses following tissue damage or infection and is a promising target for treatment of inflammatory disease. Here, we describe the identification of tozorakimab (MEDI3506), a potent, human anti-IL-33 monoclonal antibody, which can inhibit reduced IL-33 (IL-33red) and oxidized IL-33 (IL-33ox) activities through distinct serum-stimulated 2 (ST2) and receptor for advanced glycation end products - epidermal growth factor receptor (RAGE-EGFR complex) signalling pathways. We hypothesized that a therapeutic antibody would require an affinity higher than that of ST2 for IL-33, with an association rate greater than 107 M-1 s-1, to effectively neutralize IL-33 following rapid release from damaged tissue. An innovative antibody generation campaign identified tozorakimab, an antibody with a femtomolar affinity for IL-33red and a fast association rate (8.5 x 107 M-1 s-1), which was comparable to soluble ST2. Tozorakimab potently inhibited ST2-dependent inflammatory responses driven by IL-33 in primary human cells and in a murine model of lung epithelial injury. Additionally, tozorakimab prevented the oxidation of IL-33 and its activity via the RAGE/EGFR signalling pathway, thus increasing in vitro epithelial cell migration and repair. Tozorakimab is a novel therapeutic agent with a dual mechanism of action that blocks IL-33red and IL-33ox signalling, offering potential to reduce inflammation and epithelial dysfunction in human disease.

immunology↗

bioRxiv2021

A novel zebrafish model of SPEG-related centronuclear myopathy (CNM): characterization and comparison with other CNM model zebrafish

Centronuclear myopathy (CNM) is a congenital neuromuscular disorder caused by pathogenic variation in genes associated with membrane trafficking and excitation-contraction coupling (ECC). Bi-allelic autosomal recessive mutations in striated muscle enriched protein kinase (SPEG) account for a subset of CNM patients. Previous research has been limited by the perinatal lethality of Speg knockout mice. Thus, the precise biological role of SPEG in skeletal muscle remains unknown. To address this issue, we generated zebrafish spega, spegb, and spega/spegb (speg-DKO) mutant lines. We demonstrate that speg-DKO zebrafish faithfully recapitulate multiple phenotypes associated with human CNM, including disruption of the ECC protein machinery, dysregulation of calcium homeostasis during ECC, and impairment of muscle performance. Taking advantage of the availability of zebrafish models of multiple CNM genetic subtypes, we compared novel and known disease markers in speg-DKO with mtm1-KO and DNM2-S619L transgenic zebrafish. We observed desmin (DES) accumulation common to all CNM subtypes, and DNM2 upregulation in muscle of both speg-DKO and mtm1-KO zebrafish. In all, we establish a new model of SPEG-related CNM, and identify abnormalities in this model suitable for defining disease pathomechanisms and evaluating potential therapies. Summary StatementWe created a novel zebrafish speg mutant model of centronuclear myopathy that recapitulates key features of the human disorder and provides insight into pathomechanisms of the disease.

genetics↗

bioRxiv2021

A toolbox for efficient proximity-dependent biotinylation in zebrafish embryos

Understanding how proteins are organized in compartments is essential to elucidating their function. While proximity-dependent approaches such as BioID have enabled a massive increase in information about organelles, protein complexes and other structures in cell culture, to date there have been only a few studies in living vertebrates. Here, we adapted proximity labeling for protein discovery in vivo in the vertebrate model organism, zebrafish. Using lamin A (LMNA) as bait and green fluorescent protein (GFP) as a negative control, we developed, optimized, and benchmarked in vivo TurboID and miniTurbo labeling in early zebrafish embryos. We developed both an mRNA injection protocol and a transgenic system in which transgene expression is controlled by a heat shock promoter. In both cases, biotin is provided directly in the egg water, and we demonstrate that 12 hours of labeling are sufficient for biotinylation of prey proteins, which should permit time-resolved analysis of development. After statistical scoring, we found that the proximal partners of LMNA detected in each system were enriched for nuclear envelope and nuclear membrane proteins, and included many orthologs of human proteins identified as proximity partners of lamin A in mammalian cell culture. The tools and protocols developed here will allow zebrafish researchers to complement genetic tools with powerful proteomics approaches.

systems biology↗

bioRxiv2020

GATA4/5/6 family transcription factors are conserved determinants of cardiac versus pharyngeal mesoderm fate

GATA4/5/6 transcription factors play essential, conserved roles in heart development. How these factors mediate the transition from multipotent mesoderm progenitors to a committed cardiac fate is unclear. To understand how GATA4/5/6 modulate cell fate decisions we labelled, isolated, and performed single-cell gene expression analysis on cells that express gata5 at pre-cardiac time points spanning gastrulation to somitogenesis. We found that most mesendoderm-derived lineages had dynamic gata5/6 expression. In the absence of Gata5/6, the population structure of mesendoderm-derived cells was dramatically altered. In addition to the expected absence of cardiac mesoderm, we observed a concomitant expansion of cranial-pharyngeal mesoderm. Functional genetic analyses in zebrafish and the invertebrate chordate Ciona, which possess a single GATA4/5/6 homolog, revealed an essential and cell-autonomous role for GATA4/5/6 in promoting cardiac and inhibiting pharyngeal mesoderm identity. Overall, the maintenance and repression of GATA4/5/6 activity plays a critical, evolutionarily conserved role in early development.

developmental biology↗

bioRxiv2018

Heart enhancers with deeply conserved regulatory activity are established early in development

During the phylotypic period embryos from different genera show similar gene expression patterns, implying common regulatory mechanisms. To identify enhancers involved in the initial events of cardiogenesis, which occurs during the phylotypic period, we isolated early cardiac progenitor cells from zebrafish embryos and characterized 3838 open chromatin regions specific to this cell population. Of these regions, 162 overlapped with conserved non-coding elements (CNEs) that also mapped to open chromatin regions in human. Most of the zebrafish conserved open chromatin elements tested drove gene expression in the developing heart. Despite modest sequence identity, human orthologous open chromatin regions could recapitulate the spatial temporal expression patterns of the zebrafish sequence, potentially providing a basis for phylotypic gene expression patterns. Genome-wide, we discovered 5598 zebrafish-human conserved open chromatin regions, suggesting that a diverse repertoire of ancient enhancers is established prior to organogenesis and the phylotypic period.

genomics↗

bioRxiv2017

The DEAD box RNA helicase Ddx39a is essential for myocyte and lens development in zebrafish

RNA helicases from the DEAD-box family are found in almost all organisms and have important roles in RNA metabolism including RNA synthesis, processing and degradation. The function and mechanism of action of most of these helicases in animal development and human disease are largely unexplored. In a zebrafish mutagenesis screen to identify genes essential for heart development we identified a zebrafish mutant, which disrupts the gene encoding the RNA helicase DEAD-box 39a (ddx39a).Homozygous ddx39a mutant embryos exhibit profound cardiac and trunk muscle dystrophy, along with lens abnormalities caused by abrupt terminal differentiation of cardiomyocyte, myoblast and lens fiber cells. Further investigation indicated that loss of ddx39a hindered mRNA splicing of members of the kmt2 gene family, leading to mis-regulation of structural gene expression in cardiomyocyte, myoblast and lens fiber cells. Taken together, these results show that Ddx39a plays an essential role in establishment of proper epigenetic status during cell differentiation.

developmental biology↗

bioRxiv2017

Hey2 restricts cardiac progenitor addition to the developing heart

A key event in vertebrate heart development is the timely addition of second heart field (SHF) progenitor cells to the poles of the heart tube. This accretion process must occur to the proper extent to prevent a spectrum of congenital heart defects (CHDs). However, the factors that regulate this critical process are poorly understood. Here we demonstrate that Hey2, a bHLH transcriptional repressor, restricts SHF progenitor accretion to the zebrafish heart. hey2 expression demarcated a distinct domain within the cardiac progenitor population. In the absence of Hey2 function an increase in myocardial cell number and SHF progenitors was observed. We found that Hey2 limited proliferation of SHF-derived cardiomyocytes in a cell-autonomous manner, prior to heart tube formation, and further restricted the developmental window over which SHF progenitors were deployed to the heart. Taken together, our data suggests a role for Hey2 in controlling the proliferative capacity and cardiac contribution of late-differentiating cardiac progenitors.

developmental biology↗