Project description:Perkinsus marinus is an intracellular parasitic protozoan that is responsible for serious disease epizootics in marine bivalve molluscs worldwide and along with P. olseni belongs to the OIE list of notified diseases. Despite all available information on P. marinus genomics, more baseline data is required at the proteomic level for a better understanding of P. marinus biological processes, including virulence mechanisms. In the present study, we have established in vitro clonal cultures of P. marinus from infected gills and mantle tissues of C. rhizophorae to evaluate the parasite cellular proteomic profile. A high throughput label-free shotgun HDMS approach using nanoUPLC-MS was used. Our intention was to provide the first comprehensive proteome profile of P. marinus that might serve as a valuable resource for future investigations involving comparative analyses of P. marinus from different regions, as well as comparisons of different species of Perkinsus.
Project description:To investigate the virological properties of SARS-CoV-2 variants, we amplified the clinical isolates of an early pandemic D614G-bearing isolate (B.1.1 lineage, strain TKYE610670; GISAID ID: EPI_ISL_479681), a Delta isolate (B.1.617.2 lineage, strain TKYTK1734; GISAID ID: EPI_ISL_2378732) and an Omicron isolate (BA.1 lineage, strain TY38-873; GISAID ID: EPI_ISL_7418017) and prepared the working viruses.
Project description:Unscheduled R-loops are a major source of replication stress and DNA damage. R-loop-induced replication defects are sensed and suppressed by ATR kinase, whereas it is not known whether R-loop itself is actively involved in ATR activation and, if so, how this is achieved. Here, we report that the nuclear form of RNA-editing enzyme ADAR1 promotes ATR activation and resolves genome-wide R-loops, a process that requires its double-stranded RNA-binding domains. Mechanistically, ADAR1 interacts with TOPBP1 and facilitates its loading on perturbed replication forks by enhancing the association of TOPBP1 with RAD9 of the 9-1-1 complex. When replication is inhibited, DNA-RNA hybrid competes with TOPBP1 for ADAR1 binding to promote the translocation of ADAR1 from damaged fork to R-loop region. There, ADAR1 recruits RNA helicases DHX9 and DDX21 to unwind R-loops, simultaneously allowing TOPBP1 to stimulate ATR more efficiently. Collectively, we propose that the tempo-spatially regulated assembly of ADAR1-nucleated protein complexes link R-loop clearance and ATR activation, while R-loops crosstalk with blocked replication forks by transposing ADAR1 to finetune ATR activity and safeguard the genome.
Project description:Mitochondria are the central metabolic hub of the cell and their function is vital for cellular activities. Mitochondrial autophagy, or mitophagy, is a quality control mechanism to surveille the fitness and functionality of mitochondria and is therefore essential for life. Both mitochondrial dysfunction and malfunctional DNA damage response (DDR) are a major etiology for tissue impairment and aging. ATR has been shown mainly as a nuclear factor to conduct DNA damage response under DNA replication stress. Paradoxically, the human Seckel syndrome caused by ATR mutations is characterized by premature aging and neuropathies, suggesting a role of ATR in non-replicating tissues. Here we report a previously unknown yet direct role of ATR at mitochondria. We find that HSP90 chaperones ATR and PINK1 to mitochondria, where ATR interacts with and thereby stabilizes PINK1 docking at the mitochondrial translocase TOM/TIM complex as well as with the electron transport chain (ETC). ATR mutant cells are refractory to mitophagy initiation, which can be reverted by an ectopic expression of full length, but not ATR-interaction mutant, PINK1. ATR deletion alters mitochondrial dynamics and OXPHOS functions producing aberrantly high reactive oxygen species (ROS) that attack cytosolic macromolecules prior to damaging nuclear DNA. Intriguingly, pharmacological intervention of mitochondrial metabolism to prevent ROS overproduction can mute ATR-mediated nuclear DDR. This study demonstrates that ATR is an integrated component of the mitochondrial membrane to ensure mitochondrial fitness as a primary physiological function, which, together with its essential DDR function, safeguards the cell fate under physiological and genotoxic conditions.