Biology subjects

Hardy, T.

Publications and source records attributed to Hardy, T..

3 recordsLinked to original sources

bioRxiv2026

Vascular dilation modulates brain haematoma expansion in larval zebrafish

Intracerebral haemorrhage (ICH) is a severe form of stroke with high morbidity and mortality rates. For survivors, acute haematoma expansion strongly determines neurological outcome. Although blood pressure reduction is widely investigated as a strategy to limit haematoma growth, the haemodynamic mechanisms regulating haemorrhage development remain poorly understood. Zebrafish provide a tractable in vivo model to study cerebrovascular biology and spontaneous ICH, yet the contribution of vascular regulation to haemorrhage onset and expansion has not been explored in this species. Here, we investigated whether pharmacological modulation of vascular dilation influences ICH development in zebrafish larvae. We first characterised vascular changes during the developmental window in which spontaneous ICH occurs and observed increased heart rate and progressive reductions in arterial diameter between 2 and 3 days post-fertilisation, suggesting increased vascular resistance. We then tested whether vasoconstriction promotes haemorrhage using angiotensin II, which induced systemic and cerebrovascular vasoconstriction but did not increase ICH incidence or haematoma size in two independent ICH models. In contrast, pharmacological vasodilation using sodium nitroprusside or isoproterenol significantly reduced haematoma size in a high-incidence model of atorvastatin-induced ICH. Live imaging of cerebral blood flow revealed that vasodilation was associated with the confinement of red blood cells around affected vessels rather than dispersing into the brain ventricles. Together, these findings indicate that vascular dilation modulates haemorrhage progression in zebrafish ICH and establish this model as a platform to investigate haemodynamic mechanisms regulating haematoma expansion.

cell biology↗

bioRxiv2025

NEK7 phosphorylation of cortactin modulates the migratory capacity of cells expressing EML4-ALK V3

EML4-ALK is a common oncogenic driver of non-small cell lung cancer. Distinct EML4-ALK variants cause different rates of disease progression, with patients expressing variant 3 (V3) exhibiting accelerated metastasis. Cells expressing EML4-ALK V3 develop a mesenchymal-like morphology and enhanced migration that is dependent on the NEK9 and NEK7 kinases. However, downstream substrates of these kinases relevant to these phenotypes are largely unknown. Here, we show that the actin-binding protein cortactin is phosphorylated by NEK7 within the F-actin-binding region (ABR) and that depletion of cortactin abrogates the morphological and migration phenotypes induced by EML4-ALK V3. Expression of constitutively active mutants of NEK9 or NEK7 causes similar cortactin-dependent morphological and migration changes. Cortactin co-localises with NEK7 and EML4-ALK V3 at branched filopodia-like extensions that are also generated upon expression of a cortactin protein with phospho-mimetic mutations in the ABR. In contrast, phospho-null mutations dissociate cortactin from F-actin. We propose that EML4-ALK V3 alters cell morphology and promotes directed cell migration by modulating the actin cytoskeleton via NEK7-mediated phosphorylation of cortactin within its ABR. SUMMARY STATEMENTNEK7 phosphorylates key residues of cortactin in its actin-binding repeat region to modulate the actin architecture and migration of cells driven by the EML4-ALK V3 - NEK9 - NEK7 pathway.

cell biology↗

bioRxiv2019

Chromosome-length haplotigs for yak and cattle from trio binning assembly of an F1 hybrid

BackgroundAssemblies of diploid genomes are generally unphased, pseudo-haploid representations that do not correctly reconstruct the two parental haplotypes present in the individual sequenced. Instead, the assembly alternates between parental haplotypes and may contain duplications in regions where the parental haplotypes are sufficiently different. Trio binning is an approach to genome assembly that uses short reads from both parents to classify long reads from the offspring according to maternal or paternal haplotype origin, and is thus helped rather than impeded by heterozygosity. Using this approach, it is possible to derive two assemblies from an individual, accurately representing both parental contributions in their entirety with higher continuity and accuracy than is possible with other methods.\n\nResultsWe used trio binning to assemble reference genomes for two species from a single individual using an interspecies cross of yak (Bos grunniens) and cattle (Bos taurus). The high heterozygosity inherent to interspecies hybrids allowed us to confidently assign >99% of long reads from the F1 offspring to parental bins using unique k-mers from parental short reads. Both the maternal (yak) and paternal (cattle) assemblies contain over one third of the acrocentric chromosomes, including the two largest chromosomes, in single haplotigs.\n\nConclusionsThese haplotigs are the first vertebrate chromosome arms to be assembled gap-free and fully phased, and the first time assemblies for two species have been created from a single individual. Both assemblies are the most continuous currently available for non-model vertebrates.

bioinformatics↗