Tyrosine phosphatase MEG2 modulates murine development and platelet and lymphocyte activation through secretory vesicle function

Homotypic secretory vesicle fusion induced by the protein tyrosine phosphatase MEG2 depends on polyphosphoinositides in T cells.

Sec14p homology domains are found in a large number of proteins from plants, yeast, invertebrates, and higher eukaryotes. We report that the N-terminal Sec14p homology domain of the human protein tyrosine phosphatase PTP-MEG2 binds phosphatidylinositol-3,4,5-trisphosphate (PtdIns(3,4,5)P(3)) in vitro and colocalizes with this lipid on secretory vesicle membranes in intact cells. Point mutations...

Suppressive CpG

Cellular constipation can be deadly, according to a study on page 1587. Wang and colleagues show that cells get clogged with aborted secretory cargo when they lack an enzyme that helps form vesicles. Deletion of this enzyme proved lethal in mice, halting brain, bone and vascular development. The enzyme in question is a protein tyrosine phosphatase (PTP) called MEG2. MEG2 binds lipids and reside...

Basophilic Leukemia Mast Cells and Jurkat T Tyrosine Phosphatase PTP-MEG2 in Rat Enlargement of Secretory Vesicles by Protein

PTP-MEG2 is activated in polycythemia vera erythroid progenitor cells and is required for growth and expansion of erythroid cells.

Polycythemia vera (PV) is a human clonal hematologic disorder. Previously we demonstrated that erythroid colony-forming cells (ECFCs) from PV patients contained a hyperactive membrane-associated tyrosine phosphatase. We now show that this phosphatase corresponded to protein tyrosine phosphatase (PTP)-MEG2, an intracellular enzyme with a putative lipid-binding domain. The increased activity of P...

Platelet endothelial cell adhesion molecule-1 serves as an inhibitory receptor that modulates platelet responses to collagen.

Platelet responses to collagen are mediated by the combined actions of the integrin alpha2beta1, which serves as a major collagen-binding receptor, and the GPVI/FcRgamma-chain complex, which transmits collagen-specific activation signals into the cell interior through the action of an immunoreceptor tyrosine-based activation motif within the cytoplasmic domain of the FcRgamma-chain. Despite muc...