PTPϵ has a critical role in signaling transduction pathways and phosphoprotein network topology in red cells

Abstract

Protein tyrosine phosphatases (PTPs) are crucial components of cellular signal transduction pathways. We report here that red blood cells (RBCs) from mice lacking PTPε (Ptpre −/− ) exhibit abnormal morphology and increased Ca 2+ -activated-K + channel activity, which was partially blocked by the Src-Family-Kinases (SFKs) inhibitor PP1. In Ptpre −/− mouse RBCs, the activity of Fyn and Yes, two SFKs, were increased, suggesting a functional relationship between SFKs, PTPε and Ca 2+ -activated-K + -channel. The absence of PTPε markedly affected the RBC membrane tyrosine (Tyr-) phosphoproteome, indicating a perturbation of RBCs signal transduction pathways. Using signaling network computational analysis of the Tyr-phosphoproteomic data, we identified 7 topological clusters. We studied cluster 1, containing Syk-Tyr-kinase: Syk-kinase activity was higher in wild-type than in Ptpre −/− RBCs, validating the network computational analysis and indicating a novel signaling pathway, which involves Fyn and Syk in regulation of red cell morphology.

Erythrocyte membrane changes of chorea-acanthocytosis are the result of altered Lyn kinase activity

“…Erythrocytes were isolated from whole blood after removal of white blood cells and platelets as previously described. 19 Because ChAc patients have a dense fraction of RBCs and ChAc were fractionated in fraction 1 (F1) corresponding to a density Ͻ 1.074, containing reticulocytes, and fraction 2 (F2) corresponding to a density Ͼ 1.092, containing acanthocytes. (B) The fractionated RBC membrane proteins were separated by 1DE and stained with colloidal Coomassie blue.…”

Epidermal Growth Factor Receptor (EGFR)-mediated Positive Feedback of Protein-tyrosine Phosphatase ϵ (PTPϵ) on ERK1/2 and AKT Protein Pathways Is Required for Survival of Human Breast Cancer Cells

“…Abnormalities in cellular morphology, together with reduced intracellular K ϩ content and increased Ca 2ϩ -activated K ϩ channel activity were also documented in red cells from PTP⑀-deficient mice (21). In addition, at an early post-natal age these mice displayed hypomyelination in the sciatic nerve axons, most likely as a result of hyperphosphorylation of voltage-gated potassium channel Kv2.1 in Schwann cells (22,23).…”

Membrane association of peroxiredoxin-2 in red cells is mediated by the N-terminal cytoplasmic domain of band 3

“…Red cell total lysates were prepared lysing packed RBCs in E-Buffer 4X (EB-4X, 200 mM Tris pH 7.4, 400 mM NaCl, 20 mM EDTA pH 7.4, 4% Triton X-100, protease inhibitor cocktail tablet (Roche), 3 mM benzamidine and 1 mM Na 3 VO 4 final concentration) and left rotating for 1 hr at 4 °C to complete lysis and protein solubilization [18][19][20].…”