Project description:The regulation of gene expression and RNA maturation underlies fundamental processes such as cell homeostasis, development and stress acclimation. The biogenesis and modification of RNA is tightly controlled by an array of regulatory RNAs and nucleic acid-binding proteins. While the role of small RNAs (sRNAs) in gene expression has been studied in-depth in select model organisms, little is known about sRNA biology across the eukaryotic tree of life. We used deep sequencing to explore the repertoires of sRNAs encoded by the miniaturized, endosymbiotically-derived ‘nucleomorph’ genomes of two single-celled algae, the cryptophyte Guillardia theta and the chlorarachniophyte Bigelowiella natans. A total of 32.3 and 35.3 million reads were generated from G. theta and B. natans, respectively. In G. theta, we identified nucleomorph U1, U2 and U4 spliceosomal RNAs (snRNAs) as well as 11 C/D box small nucleolar RNAs (snoRNAs), five of which have potential plant and animal homologs. The snoRNAs are predicted to perform 2’-O methylation of rRNA (but not snRNA). In B. natans, we found previously undetected RNA components of the nucleomorph spliceosome (U4 snRNA) and ribosome (5S rRNA), along with six orphan sRNAs. Analysis of chlorarachniophyte snRNAs shed light on the removal of the miniature 18-21 nt introns found in B. natans nucleomorph genes. Neither of the nucleomorph genomes appears to encode RNA pseudouridylation machinery, and U5 snRNA cannot be found in the cryptophyte. Considering the central roles of U5 snRNA and RNA modifications in other organisms, cytoplasm-to-nucleomorph RNA shuttling in cryptophyte algae is a distinct possibility.
Project description:Plants and algae have developed various light harvesting mechanisms for optimal delivery of excitation energy to the photosystems. The cryptophyte algae have evolved a novel soluble light-harvesting antenna utilizing phycobilin pigments to complement the membrane-intrinsic Chl a/c-binding LHC antenna. This new antenna consists of the plastid-encoded beta-subunit, a relict of the ancestral phycobilisome, and a novel nuclear-encoded -subunit unique to cryptophytes. Together, these proteins form the active tetramer, which consists of one alpha 1 and one alpha 2 and two beta susbunits. In all cryptophyte algae investigated so far, the alpha-subunits have duplicated and diversified into a large gene family. Although there is transcriptional evidence for expression of all these genes, the x-ray structures determined to date suggest that only two of the -subunit genes might be significantly expressed at protein level. Using proteomics, we show that phycoerythrin 545 (PE545) of Guillardia theta, the only cryptophyte with a sequenced genome, all 20 alpha-subunits are expressed when the algae grow under white light. Their relative expression levels depend on the intensity of the growth light, but there is no evidence for a specific light-dependent regulation of individual members of the alpha-subunit family under the growth conditions applied. Subunit GtcpeA10 seems to be a special member of the alpha-subunit family, because it consists of two similar N- and C-terminal domains, which likely are the result of a partial gene duplication.
2017-06-20 | PXD006301 | Pride
Project description:RNA-Seq of Guillardia theta and Bigelowiella natans
Project description:To investigate the effect of bacterially secreted Theta toxin on lung cancer cells, we established co-culture of live S. typhimurium and spheroids of H460 and H1819 cell lines. Once the bacteria colonized inside the spheroids, we induced the expression of Theta toxin by the bacteria. We extracted RNA after 1 week of treatment.
Project description:DNA polymerase theta (Pol-theta)-mediated end-joining (TMEJ) repairs DNA double-strand breaks and confers resistance to genotoxic agents. How Pol-theta is regulated at the molecular level to exert TMEJ remains unknown. We find that Pol-theta interacts with and is PARylated by PARP1 in vitro and in cells. PARP1 recruits Pol-theta to the vicinity of DNA damage via PARylation dependent liquid demixing, however, PARylated Pol-theta (PAR-Pol-theta) cannot perform TMEJ due to its inability to bind DNA. PARG-mediated de-PARylation of Pol-theta reactivates its DNA binding and end-joining activities in vitro. Consistent with this, PARG is essential for TMEJ in cells and the temporal recruitment of PARG to DNA damage corresponds with TMEJ activation and dissipation of PARP1 and PAR. These studies support a two-step spatiotemporal mechanism of TMEJ regulation. First, PARP1 PARylates Pol-theta and facilitates its recruitment to DNA damage sites in an inactivated state. PARG subsequently activates TMEJ by removing repressive PAR marks on Pol-theta.
Project description:OT-1 Transgenic CD8 T-cells were isolated from spleens of WT, PKCθ theta KO, and p50 cRel DKO mice. The T-cells were either cultured with non-pulsed DC (WT only and signified as "WT - UN") or with BMDCs pulsed with the OVA peptide SIINFEKL (N4) (WT, PKCθ theta KO, and p50 cRel DKO and signified as 'genotype - N4') at a ratio of 1:10 (DC:T-cell) for 18 hours. DCs then were depleted from the culture and RNA was made from the T-cells to measure gene expression at the early / late stage of T-cell activation
Project description:Nucleomoprhs are remnants of secondary endosymbiotic events between two eukaryote cells wherein the endosymbiont has retained its eukaryotic nucleus. Nucleomoprhs have evolved at least twice independently, in chlorarachniophytes and cryptophytes, yet they have converged on a remarkably similar genomic architecture, characterized by the most extreme compression and minituarization among all known eukaryotes. Previous computational studies have suggested that nucleomorph chromatin likely exhibits a number of divergent features. In this work, we provide the first maps of open chromatin, active transcription, and three-dimensional genome architecture in the nucleomorph of the chlorarachniophyte Bigelowiella natans