Catherine J. Pears

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Poly adenosine diphosphate (ADP)-ribosylation (PARylation) by poly ADP-ribose (PAR) polymerases (PARPs) is an early response to DNA double-strand breaks (DSBs). In this paper, we exploit Dictyostelium discoideum to uncover a novel role for PARylation in regulating nonhomologous end joining (NHEJ). PARylation occurred at single-strand breaks, and two PARPs,(More)
Two homologues of mitogen-activated protein kinases have been identified in Dictyostelium discoideum (ERK1 and EKR2). We here demonstrate transient tyrosine phosphorylation of ERK2 in response to the chemoattractants cAMP and folic acid that correlates with activity. To investigate the signalling pathways, we studied the response in strains with altered(More)
Reactive oxygen species are known to have a signalling role in many organisms. In bacteria and yeast various response systems have evolved to combat oxidative stress which are triggered by reactive oxygen species. Mammals and plants are known to actively generate reactive oxygen species such as superoxide during signalling responses to a variety of(More)
DNA double-strand breaks (DSBs) can be repaired by either homologous recombination (HR) or nonhomologous end-joining (NHEJ). In vertebrates, the first step in NHEJ is recruitment of the DNA-dependent protein kinase (DNA-PK) to DNA termini. DNA-PK consists of a catalytic subunit (DNA-PKcs) that is recruited to DNA ends by the Ku70/Ku80 heterodimer. Although(More)
The structural analysis of protein kinase C has led to the identification of a family of related gene products. This family of kinases consists of six unique genes that give rise to at least seven polypeptides. The high degree of conservation and the differential distribution of these mRNAs/proteins suggest that they perform distinct functions in vivo.(More)
The Cdk8 proteins are kinases which phosphorylate the carboxy terminal domain (CTD) of RNA polymerase II (Pol II) as well as some transcription factors and, therefore, are involved in the regulation of transcription. Here, we report that a Cdk8 homologue from Dictyostelium discoideum is localized in the nucleus where it forms part of a high molecular weight(More)
Protein kinase C (PKC) consists of a family of serine/ threonine protein kinases which are presumed to play a major role in signal transduction in response to the production of diacylglycerol (reviewed by Nishizuka, 1988; Parker et al. 1989). Originally denned as a kinase dependent on phospholipid and calcium for activity, PKC was found to be the major(More)
ADP-ribosylation is the post translational modification of proteins catalysed by ADP-ribosyltransferases (ARTs). ADP-ribosylation has been implicated in a wide variety of cellular processes including cell growth and differentiation, apoptosis and transcriptional regulation. Perhaps the best characterised role, however, is in DNA repair and genome stability(More)
The cysteine proteinase 2 gene of Dictyostelium encodes a developmentally regulated sulphydryl proteinase which is first expressed late during cellular aggregation. The mRNA is slightly enriched in pre-stalk over pre-spore cells but we show here that it is expressed at a somewhat higher level in mature spore cells than in stalk cells. The mRNA is induced to(More)
GskA, the Dictyostelium GSK-3 orthologue, is modified and activated by the dual-specificity tyrosine kinase Zak1, and the two kinases form part of a signaling pathway that responds to extracellular cyclic AMP. We identify potential cellular effectors for the two kinases by analyzing the corresponding null mutants. There are proteins and mRNAs that are(More)