Biology subjects

Carr, I.

Publications and source records attributed to Carr, I..

4 recordsLinked to original sources

bioRxiv2024

Senataxin modulates resistance to cisplatin through an R-loop mediated mechanism in HPV-associated Head and Neck Squamous Cell Carcinoma

IntroductionOropharyngeal Squamous Cell Carcinoma (OPSCC) is a site defined subtype of head and neck cancer with two distinct clinical subtypes: HPV-associated (HPV+) and HPV-independent (HPV-); both of which are commonly treated with chemoradiotherapy involving cisplatin. Cisplatin creates DNA crosslinks, which lead to eventual cell death via apoptosis. Clinical outcomes in HPV-OPSCC are poor and although HPV+ has an improved response to therapy, a subset of patients suffer from distant metastases, with a poor prognosis. Therefore, there is a need to understand the molecular basis underlying treatment resistance. A common mechanism of chemotherapy resistance is upregulation of DNA repair, and a major source of endogenous DNA damage are DNA/RNA hybrids, known as R-loops. R-loops are three stranded DNA/RNA hybrids formed in the genome as a by- product of transcription and are normally transient; however, they can persist and become a source of genomic instability. The contribution of R-loops to the development of cisplatin resistance in OPSCC is unknown. MethodsHPV+ and HPV- cisplatin resistant cell lines were developed, and RNA-sequencing was used to investigate changes in gene expression. Changes in R-loop dynamics were explored using slot blots and DRIP-qPCR. The effect of depleting known R-loop regulators on cisplatin sensitivity was assessed using siRNA. R-loop burden in a cohort of HPV+ and HPV- OPSCC tumours was explored using S9.6 immunohistochemistry. ResultsDevelopment of cisplatin resistant clones led to changes in gene expression consistent with resistance, alongside alterations in the expression of known R-loop regulators. Both HPV+ and HPV- resistant cells had elevated global R-loop levels and in HPV+ resistant cells there was a corresponding upregulation of the R-loop resolving protein, senataxin, which was not observed in HPV- resistant cells. Depletion of senataxin led to increased sensitivity to cisplatin in both HPV+ and HPV- resistant cells, however, the effect was greater in HPV+ cells. Quantification of R-loop levels by S9.6 immunohistochemistry revealed that HPV+ tumours and tumours with bone metastases had a higher R-loop burden. ConclusionR-loops are involved in modulating sensitivity to cisplatin and may represent a potential therapeutic target.

molecular biology↗

bioRxiv2020

Targeting BDCA2 suppresses Plasmacytoid dendritic cell dependent interferon response and tissue fibrosis

Plasmacytoid dendritic cells (pDC) have been implicated in the pathogenesis of Scleroderma (SSc) through their ability to infiltrate the skin and secrete interferons (IFN) and proinflammatory chemokines. Blood Dendritic Cells Antigen 2 (BDCA2) is an inhibitory type II C-type lectin expressed by human pDC. Here we determined the effects of BDCA2 internalisation on pDC mediated skin inflammation and fibrosis in human preclinical models of skin inflammation and fibrosis in vitro and in vivo. BDCA2 targeting reversed TLR-signalling induced transcriptome and differentiation of pDC and suppressed their ability to induce IFN response in organotypic 3D human skin cultures in vitro. In vivo, xenotransplantation of human pDC into immunocompromised mice (XenoSCID) significantly increased IFN induced responses to topical TLR7/9 agonist and separately enhanced the fibrotic response to bleomycin. Targeting of BDCA2 strongly suppressed both of these pathological responses ameliorating skin inflammation and fibrosis. Together, these preclinical data strongly support the notion that human pDC play a key role in immune driven skin fibrosis, which can be effectively blocked by targeting BDCA2.

immunology↗

bioRxiv2019

Novel Universal Primers For Metabarcoding eDNA Surveys Of Marine Mammals And Other Marine Vertebrates

Metabarcoding studies using environmental DNA (eDNA) and high throughput sequencing (HTS) are rapidly becoming an important tool for assessing and monitoring marine biodiversity, detecting invasive species, and supporting basic ecological research. Several barcode loci targeting teleost fish and elasmobranchs have previously been developed, but to date primer sets focusing on other marine megafauna, such as marine mammals have received less attention. Similarly, there have been few attempts to identify potentially universal barcode loci which may be informative across multiple marine vertebrate Orders. Here we describe the design and validation of four new sets of primers targeting hypervariable regions of the vertebrate mitochondrial 12S and 16S rRNA genes, which have conserved priming sites across virtually all cetaceans, pinnipeds, elasmobranchs, boney fish, sea turtles and birds, and amplify fragments with consistently high levels of taxonomically diagnostic sequence variation. In silico validation using the OBITOOLS software showed our new barcode loci outperformed most existing vertebrate barcode loci for taxon detection and resolution. We also evaluated sequence diversity and taxonomic resolution of the new barcode loci in 680 complete marine mammal mitochondrial genomes demonstrating that they are effective at resolving amplicons for most taxa to the species level. Finally, we evaluated the performance of the primer sets with eDNA samples from aquarium communities with known species composition. These new primers will potentially allow surveys of complete marine vertebrate communities in single HTS metabarcoding assessments, simplifying workflows, reducing costs, and increasing accessibility to a wider range of investigators.

ecology↗

bioRxiv2018

Biallelic Mutations in LRRC56 encoding a protein associated with intraflagellar transport, cause mucociliary clearance and laterality defects

Defective motile cilia are responsible for a group of heterogeneous genetic conditions characterised by dysfunction of the apparatus responsible for generating fluid flows. Primary ciliary dyskinesia (PCD) is the prototype for such disorders and presents with impaired pulmonary mucus clearance, susceptibility to chronic recurrent respiratory infections, male infertility and laterality defects in about 50 % of patients. Here we report biallelic variants in LRRC56 (also known as ODA8), identified in two unrelated consanguineous families. The phenotype comprises laterality defects and chronic pulmonary infections. High speed video microscopy of cultured patient epithelial cells showed severely dyskinetic cilia, but no obvious ultra-structural abnormalities on routine transmission electron microscopy (TEM). Further investigation revealed that LRRC56 interacts with the intraflagellar transport (IFT) protein IFT88. The link to IFT was interrogated in Trypanosoma brucei. In this protist, LRRC56 is recruited to the cilium during axoneme construction, where it co-localises with IFT trains and facilitates the addition of dynein arms to the distal end of the flagellum. In T. brucei carrying LRRC56 null mutations, or a mutation (p.Leu259Pro) corresponding to the p.Leu140Pro variant seen in one of the affected families, we observed abnormal ciliary beat patterns and an absence of outer dynein arms restricted to the distal portion of the axoneme. Together, our findings confirm that deleterious variants in LRRC56 result in a human disease, and suggest this protein has a likely role in dynein transport during cilia assembly that is evolutionarily important for cilia motility.

genetics↗