Correction: Mutant JAK3 phosphoproteomic profiling predicts synergism between JAK3 inhibitors and MEK/BCL2 inhibitors for the treatment of T-cell acute lymphoblastic leukemia.

Following the publication of this article the authors noted that data describing precisely where phosphorylation sites in proteins modulated following JAK1 or JAK3 inhibition in mutant T-ALL samples was not clearly annotated. Therefore an additional sheet has been added to Supplementary Table 2.

Mutant JAK3 phosphoproteomic profiling predicts synergism between JAK3 inhibitors and MEK/BCL2 inhibitors for the treatment of T-cell acute lymphoblastic leukemia.

Mutations in the interleukin-7 receptor (IL7R) or the Janus kinase 3 (JAK3) kinase occur frequently in T-cell acute lymphoblastic leukemia (T-ALL) and both are able to drive cellular transformation and the development of T-ALL in mouse models. However, the signal transduction pathways downstream of JAK3 mutations remain poorly characterized. Here we describe the phosphoproteome downstream of the JAK3(L857Q)/(M511I) activating mutations in transformed Ba/F3 lymphocyte cells. Signaling pathways regulated by JAK3 mutants were assessed following acute inhibition of JAK1/JAK3 using the JAK kinase inhibitors ruxolitinib or tofacitinib. Comprehensive network interrogation using the phosphoproteomic signatures identified significant changes in pathways regulating cell cycle, translation initiation, mitogen-activated protein kinase and phosphatidylinositol-4,5-bisphosphate 3-kinase (PI3K)/AKT signaling, RNA metabolism, as well as epigenetic and apoptotic processes. Key regulatory proteins within pathways that showed altered phosphorylation following JAK inhibition were targeted using selumetinib and trametinib (MEK), buparlisib (PI3K) and ABT-199 (BCL2), and found to be synergistic in combination with JAK kinase inhibitors in primary T-ALL samples harboring JAK3 mutations. These data provide the first detailed molecular characterization of the downstream signaling pathways regulated by JAK3 mutations and provide further understanding into the oncogenic processes regulated by constitutive kinase activation aiding in the development of improved combinatorial treatment regimens.

Cardiopulmonary bypass changes the plasma proteome in children undergoing tetralogy of Fallot repair.

INTRODUCTION: Cardiopulmonary bypass (CPB) can be associated with deleterious clinical effects. However, the impact of CPB on inflammatory, immunological and other homeostatic pathways remains poorly understood. We investigated the impact of CPB on the plasma proteome in children undergoing tetralogy of Fallot repair. METHODS: Blood samples were taken from 20 children prior to and at the end of CPB and 6h, 12h and 24h after CPB. Plasma was analysed by liquid chromatography-mass spectrometry (LC-MS) in a label-free, untargeted approach. Data were analysed using Genedata software to identify peptides that were differentially expressed (p<0.01 above a false discovery rate). Proteins were identified from peptides that demonstrated differential expression. RESULTS: The proteins that were found to be differentially expressed were haptoglobin isoform 1 preproprotein, isoform 2 of semaphorin-6C, vitamin D-binding protein, inter-alpha-trypsin inhibitor, ceruloplasmin, apolipoprotein B100 and fibrinogen alpha. CONCLUSION: CPB alters the plasma proteome with differences most apparent at 6h and 12h post CPB. There was a return to baseline with no proteins differentially regulated by 24h.

Vertebrate phylogeny of antigen D10: identification of a conserved foregut cell lineage.

The monoclonal antibody 5HL-5D11-D10 to antigen D10 identifies a cell lineage that is restricted to certain tissues of the human foregut. We investigated the tissue distribution of antigen D10 in mammals, birds, reptiles, amphibians and fish by immunohistochemical staining. Tissue from human and each of ten other mammalian species showed staining of gastric mucous neck cells and glands of the cardia and antrum, Brunner's glands, peribiliary glands and periductal glands of the pancreas. Six of the mammalian species also expressed antigen D10 in mucosa of the larger bronchi, and five expressed it to varying degree in small bowel distal to the duodenum and in colon (three of these five species). Antigen was not detected in any of the three species of bird studied. Both reptiles and amphibians showed strong staining for antigen D10 in the gastric mucous neck cells and pyloric glands, and in a subpopulation of secretory cells in the oesophagus, with the amphibian also expressing antigen in some epithelial cells of the mouth and lung. Although absent from two species of bony fish, antigen D10 was expressed by small groups of epithelial cells of the intestine of a shark, and generally by the epithelial and connective tissue cells of the gut and gills, and hepatocytes of one species of ray. The presence of antigen D10 in different tissues and species was confirmed by both an indirect ELISA and immunoblot analysis of tissue extracts. Our observations suggest that the D10 epitope characterises a subpopulation of mucus-secreting cells, predominantly of the foregut and associated organs, which has been conserved throughout terrestrial vertebrate evolution.

Epitope mapping of anti-proteinase 3 and anti-myeloperoxidase antibodies.

Anti-proteinase 3 (PR3) and anti-myeloperoxidase (MPO) autoantibodies are present in many patients with Wegener's granulomatosis (WG) and microscopic polyarteritis. The aim of this study was to determine whether these antibodies bound to linear peptide sequences on their target antigens. If common linear epitopes were demonstrated, then these could be manufactured and used in diagnostic ELISAs for anti-PR3 and anti-MPO antibodies. In addition, any homology between these epitopes and bacterial or viral sequences might implicate those microorganisms in the development of these antibodies and the pathogenesis of the associated diseases. The presence of linear epitopes on PR3 and MPO was suggested by the binding of the corresponding autoantibodies to these proteins after they had been reduced with beta-mercaptoethanol (beta-ME) and denatured with SDS or boiling, and digested with proteases. Four of the 22 sera with anti-PR3 antibodies bound to PR3 in Western blots after treatment with SDS, beta-ME and boiling for 5 min. Thermal denaturation reduced the amount of binding more than other forms of denaturation. One serum with anti-PR3 antibodies bound to Lys-C and Glu-C-digested PR3 in dot blots. Linear epitopes could not be further defined by their binding in an ELISA using overlapping peptides corresponding to the PR3 molecule because of non-specific binding. Three of the five sera with anti-MPO antibodies bound to MPO in Western blots after treatment with SDS, beta-ME and boiling for 5 min. One serum with anti-MPO antibodies bound to Lys-C and Glu-C-digested MPO in dot blots. Again, linear epitopes could not be further defined using an ELISA with overlapping peptides because of non-specific binding. Some anti-PR3 and anti-MPO antibodies are likely to recognize linear epitopes, but these cannot be defined by use of a PIN ELISA system.