Evidence from cDNA clones that the rat leukocyte-common antigen (T200) spans the lipid bilayer and contains a cytoplasmic domain of 80,000 Mr

Thomas, Matthew L.; Barclay, A. Neil; Gagnon, Jean; Williams, Alan F.

doi:10.1016/0092-8674(85)90063-7

Cited by 124 publications

(64 citation statements)

References 58 publications

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“…To rule out the possibility that Bcl-X L expression in erythrocytes was due to contamination from reticulocytes or leukocytes, the Western blot was reprobed with antibodies specific for the mitochondrial marker cytochrome c oxidase 28 (Figure 2Aii) and for the leukocyte marker CD45 (Figure 2Aiii). 29 In a separate experiment, an anti-Bcl-X L -stained Western blot was also reprobed with antibodies for hematopoietic cells (anti-SHP-1 phosphatase 30 ; Figure 2Bii) and for the platelet marker CD 61 ( Figure 2Biii). 31 The total protein loaded for each lane is shown in duplicate Coomassie-stained gels (Figure 2Aiv,Biv).…”

Section: Bcl-x L and Bak Are Expressed In Erythrocyte Plasma Membranesmentioning

confidence: 99%

Erythrocyte survival is promoted by plasma and suppressed by a Bak-derived BH3 peptide that interacts with membrane-associated Bcl-XL

Walsh

Lutz

Cotter

et al. 2002

Blood

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Erythrocytes have a defined lifespan in vivo, and the signals that maintain their survival in circulation or trigger their death are unknown. Here, we investigated the control of erythrocyte survival and death in an in vitro culture system where erythrocytes survived for 10 days in serumfree medium in the presence or absence of bovine serum. Death of the cells in culture was correlated with increased exposure of phosphatidylserine and increased levels of intracellular calcium. Cell death could be suppressed by supplementing the medium with human plasma or serum, resulting in a doubling of the lifespan to 20 days. Freshly isolated erythrocytes and cultured erythrocytes were both found to express Bcl-X L and, to a lesser extent, Bak in membrane protein extracts. Treatment of the cells with a Bak-derived BH3 peptide fused to the internalization sequence of the antennapedia protein, which has previously been shown to enter cells by diffusion and antagonize Bcl-X L , resulted in substantial cell death in erythrocyte cultures. BH3-induced death was accompanied by an immediate increase in accumulation of intracellular calcium and could be suppressed by plasma, but not by the caspase inhibitor zVAD. A BH3 peptide mutated at amino acid 78 of full-length Bak required for heterodimerization with Bcl-X L had no effect on cell viability or calcium levels. We conclude that the BH3 peptide accelerates erythrocyte death through antagonization of Bcl-X L . The data suggest that erythrocyte survival is promoted by survival factors in plasma and by membrane- IntroductionCell death and survival in hematopoietic cells is regulated by signals from cell-surface receptors that either promote apoptosis, such as Fas and tumor necrosis factor (TNF), or repress cell death, such as receptors for cytokines and survival factors such as erythropoietin (EPO), interleukin 3, and insulinlike growth factor I (IGF-I). [1][2][3] Ligation of the receptors for Fas/TNF can lead directly to activation of caspases, which can act as effectors of cell death by catalyzing structural changes associated with apoptosis, including cytoskeletal reorganization and DNA fragmentation. Survival factors mediate signals through several kinases, such as phosphoinositol 3 kinase and AKT, ultimately leading to transcriptional events or to regulation of Bcl-2 family proteins. 4 The Bcl-2 family acts as central regulators of cell death in many cells [5][6][7] and is divided into 2 main groups consisting of suppressors of apoptosis, including Bcl-2, Bcl-X L , Bcl-w, and Mcl-1, and potent apoptosis promoters, including Bax, Bak, Bad, and Bid. Bcl-2 and Bcl-X L survival activity can be antagonized by heterodimerization with proteins containing a BH3 domain, which is the essential domain for the binding and proapoptotic activity of Bak, Bax, Bik, and Bid. 8 Bcl-2 and Bcl-X L are expressed in outer mitochondrial membranes where antagonization of their function is associated with rupture of the membrane, release of the proapoptotic factors cytochrome c, and activation of caspas...

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Section: Bcl-x L and Bak Are Expressed In Erythrocyte Plasma Membranesmentioning

confidence: 99%

Erythrocyte survival is promoted by plasma and suppressed by a Bak-derived BH3 peptide that interacts with membrane-associated Bcl-XL

Walsh

Lutz

Cotter

et al. 2002

Blood

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“…M10072). 20 A 1051-bp fragment of rat SHP1 was obtained by nested 3Ј-RACE PCR using Marathon cDNA Amplification Kit (Clontech) with primary and nested primers to the rat catalytic domain coding sequence. The receptor-like PTPase, rPTP-GMC1, is expressed specifically by glomerular mesangial cells and served as a negative control for the in situ experiments.…”

Section: Riboprobesmentioning

confidence: 99%

Protein-Tyrosine Phosphatases in the Vessel Wall

Wright

Seifert

Bowen‐Pope

2000

ATVB

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Abstract-Many protein-tyrosine phosphatases (PTPases) have now been identified, but little is known about PTPase expression and regulation in vascular tissue and in vascular disease. Polymerase chain reaction (PCR) amplification and cDNA fingerprinting of PTPase catalytic domains, combined with random sequencing of PCR product libraries, identified 18 (8 receptor-like and 10 cytosolic) PTPases in the rat carotid artery and revealed differential expression of 5 of these PTPases during neointima formation after balloon catheter injury. In situ hybridization was used to localize mRNA expression in vessel cross sections for the 5 differentially expressed PTPases. This revealed that for 3 PTPases (SHP1, CD45, and PTP␤), differential transcript abundance was due to appearance/loss of the cell types by which they were expressed (leukocytes for SHP1 and CD45, endothelial cells for PTP␤). However, mRNA expression of 2 PTPases (PTPL1 and PTP1B) was specifically upregulated by proliferating and migrating smooth muscle cells (SMCs) in characteristic temporal and regional patterns in response to vessel damage. Quantitative PCR analysis showed that PTP1B and PTPL1 were induced Ϸ30-fold and Ϸ60-fold, respectively, by 2 weeks after injury in the damaged vessels compared with the uninjured vessels. PTP1B was rapidly upregulated in the media after vessel injury and remained highly expressed in the developing neointima. By contrast, PTPL1 expression did not increase dramatically until the SMCs had migrated into the intima. The differential expression of PTP1B and PTPL1 by SMCs after injury suggests roles for these PTPases in the regulation of vessel wall remodeling. Key Words: protein-tyrosine phosphatase Ⅲ smooth muscle cells Ⅲ injury Ⅲ neointima Ⅲ carotid arteries A cute arterial injury stimulates smooth muscle cell (SMC) proliferation in the media, followed by the migration of SMCs into the intima. These events result in vessel wall remodeling and the formation of a neointima. Multiple secreted growth factors mediate the SMC proliferation and migration that occurs after balloon catheter injury of the normal rat carotid artery. Basic fibroblast growth factor appears to be the major mitogen driving early medial SMC proliferation, whereas platelet-derived growth factor has a lesser effect on SMC replication but plays a major role in promoting the migration of SMCs into the intima. [1][2][3] Protein-tyrosine phosphatases (PTPases) reverse the activity of growth factor receptor tyrosine kinases and likely play important roles in the vessel wall; however, little is known of the identity of PTPases expressed by vascular tissue, and less is known about the potential roles of specific PTPases in active remodeling. Approximately 70 to 80 PTPases have been cloned and described. 4 The family is broadly divided between receptor-like and cytosolic enzymes and is further divided by the similarities of accessory and regulatory motifs. 5 The receptor PTPases generally contain an extracellular region with adhesion-like motifs, a single membranes...

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“…PTKases are notable in that they are the cytoplasmic, catalytic portion for many growth factor receptors, and the genes that encode them are potential oncogenes (1) (3,4)], LAR (LCA related) (5), and two forms isolated from Drosophila melanogaster, DLAR and DPTP (6). DLAR appears to be the Drosophila homologue to human LAR since the PTPase domains are -72% identical.…”

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confidence: 99%

Identification of an additional member of the protein-tyrosine-phosphatase family: evidence for alternative splicing in the tyrosine phosphatase domain.

Matthews

Cahir

Thomas

1990

Proc. Natl. Acad. Sci. U.S.A.

139

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Protein-tyrosine-phosphatases (protein-tyrosine-phosphate phosphohydrolase, EC 3.13.48) have been implicated in the regulation ofcell growth; however, to date few tyrosine phosphatases have been characterized. To identify additional family members, the cDNA for the human tyrosine phosphatase leukocyte common antigen (LCA; CD45) was used to screen, under low stringency, a mouse pre-B-cell cDNA library. Two cDNA clones were isolated and sequence analysis predicts a protein sequence of 793 amino acids. We have named the molecule LRP (LCA-related phosphatase). RNA transfer analysis indicates that the cDNAs were derived from a 3.2-kilobase mRNA. The LRP mRNA is transcribed in a wide variety of tissues. The predicted protein structure can be divided into the following structural features: a short 19-amino acid leader sequence, an exterior domain of 123 amino acids that is predicted to be highly glycosylated, a 24-amino acid membrane-spanning region, and a 627-amino acid cytoplasmic region. The cytoplasmic region contains two --260-amino acid domains, each with homology to the tyrosine phosphatase family. One of the cDNA clones differed in that it had a 108-base-pair insertion that, while preserving the reading frame, would disrupt the first protein-tyrosine-phosphatase domain. Analysis of genomic DNA indicates that the insertion is due to an alternatively spliced exon. LRP appears to be evolutionarily conserved as a putative homologue has been identified in the invertebrate Styela plicata.

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Evidence from cDNA clones that the rat leukocyte-common antigen (T200) spans the lipid bilayer and contains a cytoplasmic domain of 80,000 Mr

Cited by 124 publications

References 58 publications

Erythrocyte survival is promoted by plasma and suppressed by a Bak-derived BH3 peptide that interacts with membrane-associated Bcl-XL

Erythrocyte survival is promoted by plasma and suppressed by a Bak-derived BH3 peptide that interacts with membrane-associated Bcl-XL

Protein-Tyrosine Phosphatases in the Vessel Wall

Identification of an additional member of the protein-tyrosine-phosphatase family: evidence for alternative splicing in the tyrosine phosphatase domain.

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