In mammalian cells, the DNA damage-related histone H2A variant H2A.X is characterized by a C-terminal tyrosyl residue, Tyr-142, which is phosphorylated by an atypical kinase, WSTF. The phosphorylation status of Tyr-142 in H2A.X has been shown to be an important regulator of the DNA damage response by controlling the formation of ␥H2A.X foci, which are platforms for recruiting molecules involved in DNA damage repair and signaling. In this work, we present evidence to support the identification of the Eyes Absent (EYA) phosphatases, protein-tyrosine phosphatases of the haloacid dehalogenase superfamily, as being responsible for dephosphorylating the C-terminal tyrosyl residue of histone H2A.X. We demonstrate that EYA2 and EYA3 displayed specificity for Tyr-142 of H2A.X in assays in vitro. Suppression of eya3 by RNA interference resulted in elevated basal phosphorylation and inhibited DNA damage-induced dephosphorylation of Tyr-142 of H2A.X in vivo. This study provides the first indication of a physiological substrate for the EYA phosphatases and suggests a novel role for these enzymes in regulation of the DNA damage response.Unlike kinases, which are derived from a common ancestor, the opposing phosphatases have evolved in separate, structurally distinct families. In fact, a variety of catalytic mechanisms have been harnessed to facilitate protein dephosphorylation. The protein-Ser/Thr phosphatases, such as the PPP and PPM families, mediate dephosphorylation by using two metal ions at the active site, activating a water molecule for nucleophilic attack on the substrate phosphate in a single-step reaction (1). The family of Cys-dependent protein-tyrosine phosphatases (PTPs) 4 utilizes a two-step catalytic mechanism involving an essential nucleophilic cysteinyl residue, which forms a Cysphosphate intermediate (2). More recently, a third family of Asp-dependent phosphatases belonging to the haloacid dehalogenase (HAD) superfamily (3) has been gaining prominence.Various HAD phosphatases have been linked to fundamental aspects of control of cell function. One of the best characterized is FCP1, which is an important regulator of transcription through dephosphorylation of the C-terminal domain of RNA polymerase II (4). Chronophin has been shown to dephosphorylate Ser-3 in cofilin and thereby function as a regulator of the actin cytoskeleton (5). More recently, a HAD phosphatase known as Dullard has been shown to dephosphorylate the phosphatidic acid phosphatase lipin, functioning in a phosphatase cascade that regulates nuclear membrane biogenesis (6). In these cases, the HADs are functioning as protein-Ser/Thr phosphatases. However, there is now also an example of a member of the HAD superfamily with the capacity to dephosphorylate phosphotyrosyl residues in substrates.Eyes Absent (EYA) was identified initially as a component of a network of transcription regulators, the retinal determination gene network that is responsible for eye development in Drosophila. It is now known to be involved in tissue and organ developme...

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African swine fever is one of the most dangerous diseases of swine. We confirmed the 2019 outbreak in Vietnam by real-time reverse transcription PCR. The causative strain belonged to p72 genotype II and was 100% identical with viruses isolated in China (2018) and Georgia (2007). International prevention and control collaboration is needed.

The receptor-type protein tyrosine phosphatases (RPTPs) have been linked to signal transduction, cell adhesion, and neurite extension. PTPRT/RPTPq is exclusively expressed in the central nervous system and regulates synapse formation by interacting with cell adhesion molecules and Fyn protein tyrosine kinase. Overexpression of PTPRT in cultured neurons increased the number of excitatory and inhibitory synapses by recruiting neuroligins that interact with PTPRT through their ecto-domains. In contrast, knockdown of PTPRT inhibited synapse formation and withered dendrites. Incubation of cultured neurons with recombinant proteins containing the extracellular region of PTPRT reduced the number of synapses by inhibiting the interaction between ecto-domains. Synapse formation by PTPRT was inhibited by phosphorylation of tyrosine 912 within the membrane-proximal catalytic domain of PTPRT by Fyn. This tyrosine phosphorylation reduced phosphatase activity of PTPRT and reinforced homophilic interactions of PTPRT, thereby preventing the heterophilic interaction between PTPRT and neuroligins. These results suggest that brain-specific PTPRT regulates synapse formation through interaction with cell adhesion molecules, and this function and the phosphatase activity are attenuated through tyrosine phosphorylation by the synaptic tyrosine kinase Fyn.

Cellular redox control is often mediated by oxidation and reduction of cysteine residues in the redox-sensitive proteins, where thioredoxin and glutaredoxin (Grx) play as electron donors for the oxidized proteins. Despite the importance of protein-protein interactions between the electron donor and acceptor proteins, there has been no structural information for the interaction of thioredoxin or Grx with natural target proteins. Here, we present the crystal structure of a novel Haemophilus influenza peroxiredoxin (Prx) hybrid Prx5 determined at 2.8-Å resolution. The structure reveals that hybrid Prx5 forms a tightly associated tetramer where active sites of Prx and Grx domains of different monomers interact with each other. The Prx-Grx interface comprises specific charge interactions surrounded by weak interactions, providing insight into the target recognition mechanism of Grx. The tetrameric structure also exhibits a flexible active site and alternative Prx-Grx interactions, which appear to facilitate the electron transfer from Grx to Prx domain. Differences of electron donor binding surfaces in Prx proteins revealed by an analysis based on the structural information explain the electron donor specificities of various Prx proteins.