Biology subjects

Dockery, P.

Publications and source records attributed to Dockery, P..

3 recordsLinked to original sources

bioRxiv2024

Peroxiredoxin 2 Regulates DAF-16/FOXO Mediated Mitochondrial Remodelling in Response to Exercise that is Disrupted in Ageing

Ageing is associated with mitochondrial dysfunction and increased oxidative stress. Exercise generates endogenous reactive oxygen species (ROS) and promotes rapid mitochondrial remodelling. We investigated the role of Peroxiredoxin 2 (PRDX-2) in mitochondrial adaptations to exercise and ageing using Caenorhabditis elegans as a model system. PRDX-2 was required for the mitochondrial remodelling in response to exercise mediated by DAF-16 nuclear localisation. Employing an acute exercise and recovery cycle, we demonstrated exercise-induced mitochondrial ER contact sites (MERCS) assembly and mitochondrial remodelling dependent on PRDX-2 and DAF-16 signalling. There was increased mitochondrial fragmentation, elevated ROS and an altered redox state of PRDX-2, concomitant with impaired DAF-16 nuclear localisation during ageing. Similarly, the prdx-2 mutant strain exhibited increased mitochondrial fragmentation and a failure to activate DAF-16 required for mitochondrial fusion. Collectively, our data highlight the critical role of PRDX-2 in orchestrating mitochondrial remodelling in response to a physiological stress by regulating DAF-16 nuclear localisation. Graphical abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=95 SRC="FIGDIR/small/593975v2_ufig1.gif" ALT="Figure 1"> View larger version (30K): org.highwire.dtl.DTLVardef@50b94forg.highwire.dtl.DTLVardef@1b62d31org.highwire.dtl.DTLVardef@1511d0eorg.highwire.dtl.DTLVardef@4a9b6d_HPS_FORMAT_FIGEXP M_FIG C_FIG HighlightsO_LIExercise generates ROS and promotes mitochondrial remodelling dependent on DAF-16. C_LIO_LIExercise induces mitochondrial ER contact site assembly and mitochondrial dynamics. C_LIO_LIAgeing and loss of PRDX-2 results in disrupted mitochondrial fusion. C_LIO_LIThe redox state of PRDX-2 determines appropriate DAF-16 nuclear localisation. C_LI

molecular biology↗

bioRxiv2022

Centrosome Amplification promotes cell invasion via cell-cell contact disruption and Rap-1 activation

Centrosome amplification (CA) is a prominent feature of human cancers linked to genomic instability and tumourigenesis in vivo. CA is observed as early as pre-malignant metaplasia, with CA incidence increasing as the disease progresses from dysplasia to neoplasia. However, the mechanistic contributions of CA to tumourigenesis (tumour architecture and remodelling) are poorly understood. Using non-tumourigenic breast cells (MCF10A), we demonstrate that CA induction (by CDK1 inhibition or PLK4 overexpression) alone increased both cell migration, invasion and Extracellular Matrix (ECM) remodeling. Mechanistically, CA induction activated small GTPase Rap-1. We demonstrated the key role of Rap-1 mediated signalling in CA induced tumourigenesis through Rap-1 inhibition (using GGTI-298) which blocked CA-induced migration, invasion and ECM attachment. CA induction in a long-term MCF10A cell culture system disrupted epithelial cell-cell junction integrity, via dysregulation of expression and subcellular localisation of cell junction proteins (ZO-1, Occludin, JAM-A & {beta}-catenin). At the ultrastructural level, CA significantly inhibited apical junctional complex formation, as visualized by transmission electron microscopy. CA induction in the luminal A breast cancer cell line MCF7 revealed similar trends in cell junction disruption. Furthermore, CA induction in MCF10A elevated expression of integrin {beta}-3, matrix metalloprotease MMP1 and MMP13 facilitating the observed ECM attachment, degradation and cell invasion phenotype. In vivo validation using a Chicken Embryo xenograft model, showed CA positive (CA+) MCF10A cells invaded into the chicken mesodermal layer, characterised by inflammatory cell infiltration and a marked focal reaction between chorioallantoic membrane and cell graft. This reaction was inhibited by pre-treatment of CA+ MCF10A cells with GGTI-298. Interestingly, in metastatic breast cancer cells with high levels of endogenous CA (triple negative cell line MDA-MB-231) inhibition of this CA-signalling pathway (using PLK4 inhibitor Centrinone B) abrogated their metastatic capacity in vitro. This demonstrates dual roles for CA signalling, for initiating and maintaining the CA-induced metastatic phenotype. Here, we demonstrated that CA induction in normal non-tumourigenic cells acts through Rap-1-dependent signaling to confer early pro-tumourigenic changes promoting tumour progression, mediated by ECM disruption, and altered cell-cell contacts. These insights reveal that in normal cells, CA induction alone (without additional pro-tumorigenic alterations) is sufficient to induce tumourigenesis and CA-mediated signaling supports a metastatic phenotype. StatementCentrosome amplification alone drives early tumourigenic change in normal breast epithelial cells

cell biology↗

bioRxiv2022

In vitro evolution of Listeria monocytogenes reveals selective pressure for loss of SigB and AgrA function at different incubation temperatures.

The alternative sigma factor B ({sigma}B) contributes to the stress tolerance of the foodborne pathogen Listeria monocytogenes by upregulating the General Stress Response. We previously showed that {sigma}B loss-of-function mutations arise frequently in strains of L. monocytogenes, and suggested that mild stresses might favour the selection of such mutations. In this study, we performed in vitro evolution experiments (IVEE) where L. monocytogenes was allowed to evolve over 30 days at elevated (42{degrees}C) or lower (30{degrees}C) incubation temperatures. Isolates purified throughout the IVEE revealed the emergence of sigB operon mutations at 42{degrees}C. However, at 30{degrees}C independent alleles in the agr locus arose, resulting in the inactivation of the Agr quorum sensing. Colonies of both sigB- and agr- strains exhibited a greyer colouration on 7-days-old agar plates compared with the parental strain. Scanning electron microscopy revealed a more complex colony architecture in the wild type than in the mutant strains. sigB- strains outcompeted the parental strain at 42{degrees}C, but not at 30{degrees}C, whilst agr- strains showed a small increase in competitive fitness at 30{degrees}C. Analysis of 40,080 L. monocytogenes publicly available genome sequences revealed a high occurrence rate of premature stop codons in both the sigB and agrCA loci. An analysis of a local L. monocytogenes strain collection revealed 5 out of 168 strains carrying agrCA alleles. Our results suggest that the loss of {sigma}B or Agr confer an increased competitive fitness in some specific conditions and this likely contributes to the emergence of these alleles in strains of L. monocytogenes. ImportanceTo withstand environmental aggressions L. monocytogenes upregulates a large regulon through the action of the alternative sigma factor B ({sigma}B). However, {sigma}B becomes detrimental for L. monocytogenes growth under mild stresses, which confer a competitive advantage to {sigma}B loss-of-function alleles. Temperatures of 42{degrees}C, a mild stress, are often employed in mutagenesis protocols of L. monocytogenes and promote the emergence of {sigma}B loss-of-function alleles in the sigB operon. In contrast, lower temperatures of 30{degrees}C promote the emergence of Agr loss-of-function alleles, a cell-cell communication mechanism in L. monocytogenes. Our findings demonstrate that loss-of-function alleles emerge spontaneously in laboratory-grown strains. These alleles rise in the population as a consequence of the trade-off between growth and survival imposed by the activation of {sigma}B in L. monocytogenes. Additionally, our results demonstrate the importance of identifying unwanted hitchhiker mutations in newly constructed mutant strains.

molecular biology↗