Biomedical subjects

L Cantley

Publications and source records attributed to L Cantley.

At least 19 recordsLinked to original sources

PubMed2001

Phosphatidylinositol 3-kinase confers resistance to encephalomyocarditis and herpes simplex virus-induced cell death through the activation of distinct downstream effectors.

The Janus kinase/STAT pathway has emerged as the paradigm of IFN-induced protection from viral infections. However, the possible participation of other signaling proteins in this protection is not clearly understood. In this report, we demonstrate that activation of phosphatidylinositol 3-kinase (PI3K) by either serum factors or IFNs blocks cell death induced by encephalomyocarditis virus (EMCV) and HSV. This increased resistance to virus-induced cell death does not involve the activation of the STAT pathway and occurs in the presence of normal viral replication. Interestingly, the cell uses two different PI3K regulated pathways to block EMCV- and HSV-induced cell death. The increased sensitivity of p85alpha(-/-) embryonic fibroblasts to EMCV-induced cell death is specifically corrected by overexpression of an activated allele of Akt/protein kinase B, but not activated mitogen-activated protein kinase extracellular kinase. Conversely, the augmented sensitivity of p85alpha(-/-) cells to HSV-induced cell death was compensated for by expression of an activated form of mitogen-activated protein kinase extracellular kinase, but not by activated Akt/protein kinase B. We conclude from these data that PI3K-activated pathways function in parallel with the Janus kinase/STAT pathway to protect cells from the lethal effects of viruses.

Animals↗

PubMed2001

Postmortem biochemical markers of experimentally induced hypomagnesaemic tetany in sheep.

Hypomagnesaemic tetany was induced in non-lactating and lactating ewes by feeding them semi-synthetic low magnesium diets containing additional potassium chloride and citric acid. Aqueous and vitreous humour were sampled from one eye at the time of death (fresh) and from the second eye after the head had been stored at ambient temperature for 24 hours (24-hour). There were significant relationships between the concentrations of magnesium in cerebrospinal fluid and plasma and its concentrations in fresh aqueous humour and fresh vitreous humour. Magnesium concentrations of < 0.33 mmol/litre in fresh aqueous humour and < 0.50 mmol/litre in 24-hour aqueous humour were associated with severe hypomagnesaemia and tetany. However, the concentration of magnesium in aqueous humour is relatively unstable and, unless the time of death was known accurately, its interpretation would be difficult. Magnesium concentrations of < 0.60 mmol/litre in fresh vitreous humour and < 0.65 mmol/litre in 24-hour vitreous humour were associated with severe hypomagnesaemia and tetany in adult sheep. The concentration of magnesium in vitreous humour was relatively stable for up to 48 hours postmortem.

Animals↗

PubMed2001

Cell surface glypicans are low-affinity endostatin receptors.

Endostatin, a collagen XVIII fragment, is a potent anti-angiogenic protein. We sought to identify its endothelial cell surface receptor(s). Alkaline phosphatase- tagged endostatin bound endothelial cells revealing two binding affinities. Expression cloning identified glypican, a cell surface proteoglycan as the lower-affinity receptor. Biochemical and genetic studies indicated that glypicans' heparan sulfate glycosaminoglycans were critical for endostatin binding. Furthermore, endostatin selected a specific octasulfated hexasaccharide from a sequence in heparin. We have also demonstrated a role for endostatin in renal tubular cell branching morphogenesis and show that glypicans serve as low-affinity receptors for endostatin in these cells, as in endothelial cells. Finally, antisense experiments suggest the critical importance of glypicans in mediating endostatin activities.

3T3 Cells↗

PubMed1999

Expression of c-ret promotes morphogenesis and cell survival in mIMCD-3 cells.

c-Ret, a protein tyrosine kinase receptor, and its ligand glial-derived neurotropic factor (GDNF) are critical for early regulation of ureteric bud development and nephrogenesis. To address whether c-ret directly initiates epithelial cell morphogenesis, the c-ret receptor was expressed in murine inner medullary collecting duct cells (mIMCD-3, a cell line of ureteric bud origin, which has no detectable endogenous c-ret expression). Stable expression of wild-type c-ret was found to yield a constitutively tyrosine-phosphorylated receptor, with no change after the addition of GDNF. Examination of mRNA from these cells demonstrated the message for endogenous GDNF, suggesting that c-ret was potentially being constitutively activated by an autocrine mechanism. When mIMCD-3 cells stably expressing the phosphorylated c-ret receptor were cultured in a type I collagen matrix, they exhibited little GDNF-independent or -dependent branching process formation at early time points compared with the known morphogen hepatocyte growth factor (HGF) (48 h; control, 0.33 +/- 0.33; GDNF, 1.0 +/- 0.58, P = nonsignificant; and HGF, 6.33 +/- 0.33 processes/20 cell clusters, P < 0.001), whereas extended culture (7 days) under serum-free conditions revealed a marked increase in cell survival and the spontaneous development of rudimentary branching process formation. Extended culture (7 days) of c-ret-expressing clones in type I collagen with the epithelial morphogens HGF and/or epidermal growth factor (EGF) resulted in the development of complex three-dimensional spiny cysts, whereas parental mIMCD-3 cells died under these conditions. We conclude that activated c-ret appears to mediate epithelial morphogenesis by prolonging cell survival and, in conjunction with activation of the morphogenic receptors c-met and the EGF receptor, initiates the events required for very early branching morphogenesis.

Animals↗

PubMed1997

High-affinity binding of the Drosophila Numb phosphotyrosine-binding domain to peptides containing a Gly-Pro-(p)Tyr motif.

The phosphotyrosine-binding (PTB) domain is a recently identified protein module that has been characterized as binding to phosphopeptides containing an NPXpY motif (X = any amino acid). We describe here a novel peptide sequence recognized by the PTB domain from Drosophila Numb (dNumb), a protein involved in cell fate determination and asymmetric cell division during the development of the Drosophila nervous system. Using a Tyr-oriented peptide library to screen for ligands, the dNumb PTB domain was found to bind selectively to peptides containing a YIGPYphi motif (phi represents a hydrophobic residue). A synthetic peptide containing this sequence bound specifically to the isolated dNumb PTB domain in solution with a dissociation constant (Kd) of 5.78 +/- 0.74 microM. Interestingly, the affinity of this peptide for the dNumb PTB domain was increased (Kd = 1.41 +/- 0.10 microM) when the second tyrosine in the sequence was phosphorylated. Amino acid substitution studies of the phosphopeptide demonstrated that a core motif of sequence GP(p)Y is required for high-affinity binding to the dNumb PTB domain. Nuclear magnetic resonance experiments performed on isotopically labeled protein complexed with either Tyr- or pTyr-containing peptides suggest that the same set of amino acids in the dNumb PTB domain is involved in binding both phosphorylated and nonphosphorylated forms of the peptide. The in vitro selectivity of the dNumb PTB domain is therefore markedly different from those of the Shc and IRS-1 PTB domains, in that it interacts preferentially with a GP(p)Y motif, rather than NPXpY, and does not absolutely require ligand phosphorylation for binding. Our results suggest that the PTB domain is a versatile protein module, capable of exhibiting varied binding specificities.

Animals↗

PubMed1996

Extracellular human immunodeficiency virus type-1 Tat protein activates phosphatidylinositol 3-kinase in PC12 neuronal cells.

We have here investigated the effect of the regulatory Tat protein of the human immunodeficiency virus type 1 (HIV-1) on the PI 3-kinase catalytic activity in PC12 rat pheochromocytoma cells. After as early as 1 min from the beginning of the treatment with recombinant HIV-1 Tat protein, a significant increase in the tyrosine phosphorylation levels of the p85 regulatory subunit of PI 3-kinase was noticed in 48 h serum-starved PC12 cells. Moreover, the addition of Tat to PC12 cells induced a great increase in PI 3-kinase immunoprecipitated with an anti-phosphotyrosine antibody with a peak of activity (19-fold increase with respect to the basal levels) after a 15-min treatment. This increase in PI 3-kinase activity was significantly higher in PC12 cell cultures supplemented with Tat protein than in cultures stimulated by 100 ng/ml nerve growth factor (NGF; 8-fold increase with respect to the basal levels). Further experiments showed that Tat protein was able to specifically activate PI 3-kinase at picomolar concentrations. In fact: (i) maximal activation of PI 3-kinase was observed at concentrations as low as 1 ng/ml and was specifically blocked by anti-Tat neutralizing antibody; (ii) a Tat-dependent activation was also observed in experiments in which PI 3-kinase activity was evaluated in either anti-Tyr(P) or anti-p85 immunoprecipitates; (iii) 100 nM wortmannin completely blocked the Tat-mediated increase in PI 3-kinase activity both in vitro and in vivo. Our data strongly support the concept that extracellular Tat acts as a cell stimulator, inducing intracellular signal transduction in uninfected cells.

Animals↗

PubMed1996

A mammalian adaptor protein with conserved Src homology 2 and phosphotyrosine-binding domains is related to Shc and is specifically expressed in the brain.

The Shc adaptor protein, hereafter referred to as ShcA, possesses two distinct phosphotyrosine-recognition modules, a C-terminal Src homology 2 (SH2) domain and an N-terminal phosphotyrosine-binding (PTB) domain, and is itself phosphorylated on tyrosine in response to many extracellular signals. Phosphorylation of human ShcA at Tyr-317 within its central (CH1) region induces binding to the Grb2 SH2 domain and is thereby implicated in activation of the Ras pathway. Two shc-related genes (shcB and shcC) have been identified in the mouse. shcB is closely related to human SCK, while shcC has not yet been found in other organisms. The ShcC protein is predicted to have a C-terminal SH2 domain, a CH1 region with a putative Grb2-binding site, and an N-terminal PTB domain. The ShcC and ShcB SH2 domains bind phosphotyrosine-containing peptides and receptors with a specificity related to, but distinct from, that of the ShcA SH2 domain. The ShcC PTB domain specifically associates in vitro with the autophosphorylated receptors for nerve growth factor and epidermal growth factor. These results indicate that ShcC has functional SH2 and PTB; domains. In contrast to shcA, which is widely expressed, shcC RNA and proteins are predominantly expressed in the adult brain. These results suggest that ShcC may mediate signaling from tyrosine kinases in the nervous system, such as receptors for neurotrophins.

3T3 Cells↗

PubMed1996

p120cbl is a major substrate of tyrosine phosphorylation upon B cell antigen receptor stimulation and interacts in vivo with Fyn and Syk tyrosine kinases, Grb2 and Shc adaptors, and the p85 subunit of phosphatidylinositol 3-kinase.

We and others have demonstrated that the c-cbl proto-oncogene product is one of the earliest targets of tyrosine phosphorylation upon T cell receptor stimulation. Given the similarities in the B and T lymphocyte antigen receptors, and the induction of pre-B leukemias in mice by the v-cbl oncogene, we examined the potential involvement of Cbl in B cell receptor signaling. We demonstrate prominent and early tyrosine phosphorylation of Cbl upon stimulation of human B cell lines through surface IgM. Cbl was associated in vivo with Fyn and, to a lesser extent, other Src family kinases. B cell activation also induced a prominent association of Cbl with Syk tyrosine kinase. A substantial fraction of Cbl was constitutively associated with Grb2 and this interaction was mediated by Grb2 SH3 domains. Tyrosine-phosphorylated Shc, which prominently associated with Grb2, was detected in association with Cbl in activated B cells. Thus, Grb2 and Shc adaptors, which associate with immunoreceptor tyrosine based activation motifs, may link Cbl to the B cell receptor. B cell activation also induced a prominent association between Cbl and the p85 subunit of phosphatidylinositol (PI) 3-kinase resulting in the association of a substantial fraction of PI 3-kinase activity with Cbl. Thus, Cbl is likely to play an important role to couple the B cell receptor to the PI 3-kinase pathway. Our results strongly suggest a role for p120cbl in signaling downstream of the B cell receptor and support the idea that Cbl participates in a general signal transduction function downstream of the immune cell surface receptors.

Adaptor Proteins, Signal Transducing↗

PubMed1996

Effect of water diuresis and water restriction on expression of HSPs-27, -60 and -70 in rat kidney.

Expression of HSP-27, HSP-60 and HSP-70 was estimated in the cortex, outer medulla and inner medulla (papilla) of rats undergoing water diuresis or water restriction for two days. The mRNAs for HSP-27 and HSP-60 in renal papilla were two- to threefold greater in rats during water restriction than in those excreting a dilute urine, but levels of mRNA for HSP-70 were not reduced by water diuresis and Western analysis for HSP-70 protein showed no difference between water-loaded and water-restricted animals.

Animals↗

PubMed1996

Platelet-derived growth factor-dependent activation of phosphatidylinositol 3-kinase is regulated by receptor binding of SH2-domain-containing proteins which influence Ras activity.

Upon binding of platelet-derived growth factor (PDGF), the PDGF beta receptor (PDGFR) undergoes autophosphorylation on distinct tyrosine residues and binds several SH2-domain-containing signal relay enzymes, including phosphatidylinositol 3-kinase (PI3K), phospholipase C gamma (PLC gamma), the GTPase-activating protein of Ras (RasGAP), and the tyrosine phosphatase SHP-2. In this study, we have investigated whether PDGF-dependent PI3K activation is affected by the other proteins that associate with the PDGFR. We constructed and characterized a series of PDGFR mutants which contain binding sites for PI3K as well as one additional protein, either RasGAP, SHP-2, or PLC gamma. While all of the receptors had wild-type levels of PDGF-stimulated tyrosine kinase activity and associated with comparable amounts of PI3K activity, their abilities to trigger accumulation of PI3K products in vivo differed dramatically. The wild-type receptor, as well as receptors that recruited PI3K or PI3K and SHP-2, were all capable of fully activating PI3K. In contrast, receptors that associated with PI3K and RasGAP or PI3K and PLC gamma displayed a greatly reduced ability to stimulate production of PI3K products. When this series of receptors was tested for their ability to activate Ras, we observed a strong positive correlation between Ras activation and PI3K activation. Further investigation of the relationship between Ras and PI3K indicated that Ras was upstream of PI3K. Thus, activation of PI3K requires not only binding of PI3K to the tyrosine-phosphorylated PDGFR but accumulation of GTP-bound Ras as well. Furthermore, PLC gamma and RasGAP negatively modulate PDGF-dependent PI3K activation. Finally, PDGF-stimulated signal relay can be regulated by altering the ratio of SH2-domain-containing enzymes that are recruited to the PDGFR.

3T3 Cells↗

PubMed1995

T cell activation-dependent association between the p85 subunit of the phosphatidylinositol 3-kinase and Grb2/phospholipase C-gamma 1-binding phosphotyrosyl protein pp36/38.

Tyrosine phosphorylation of cellular proteins is an early and an essential step in T cell receptor-mediated lymphocyte activation. Tyrosine phosphorylation of transmembrane receptor chains (such as zeta and CD3 chains) and membrane-associated proteins provides docking sites for SH2 domains of adaptor proteins and signaling enzymes, resulting in their recruitment in the vicinity of activated receptors. pp36/38 is a prominent substrate of early tyrosine phosphorylation upon stimulation through the T cell receptor. The tyrosine-phosphorylated form of pp36/38 is membrane-associated and directly interacts with phospholipase C-gamma 1 and Grb2, providing one mechanism to recruit downstream effectors to the cell membrane. Here, we demonstrate that in Jurkat T cells, pp36/38 associates with the p85 subunit of phosphatidylinositol 3-kinase (PI-3-K p85) in an activation-dependent manner. Association of pp36/38 with PI-3-K p85 was confirmed by transfection of a hemagglutinin-tagged p85 alpha cDNA into Jurkat cells followed by anti-hemagglutinin immunoprecipitation. In vitro binding experiments with glutathione S-transferase fusion proteins of PI-3-K p85 demonstrated that the SH2 domains, but not the SH3 domain, mediated binding to pp36/38. This binding was selectively abrogated by phosphopeptides that bind to p85 SH2 domains with high affinity. Filter binding assays demonstrated that association between pp36/38 and PI-3-K p85 SH2 domains was due to direct binding. These results strongly suggest the role of pp36/38 in recruiting PI-3-K to the cell membrane and further support the idea that pp36/38 is a multifunctional docking protein for SH2 domain-containing signaling proteins in T cells.

Adaptor Proteins, Signal Transducing↗

PubMed1995

The SH3 domain-binding T cell tyrosyl phosphoprotein p120. Demonstration of its identity with the c-cbl protooncogene product and in vivo complexes with Fyn, Grb2, and phosphatidylinositol 3-kinase.

Previously, we have identified p120 as a Fyn/Lck SH3 and SH2 domain-binding protein that is tyrosine phosphorylated rapidly after T cell receptor triggering. Here, we used direct protein purification, amino acid sequence analysis, reactivity with antibodies, and two-dimensional gel analyses to identify p120 as the human c-cbl protooncogene product. We demonstrate in vivo complexes of p120cbl with Fyn tyrosine kinase, the adaptor protein Grb2, and the p85 subunit of phosphatidylinositol (PI) 3-kinase. The association of p120cbl with Fyn and the p85 subunit of PI 3-kinase (together with PI 3-kinase activity) was markedly increased by T cell activation, consistent with in vitro binding of p120cbl to their SH2 as well as SH3 domains. In contrast, a large fraction of p120cbl was associated with Grb2 prior to activation, and this association did not change upon T cell activation. In vitro, p120cbl interacted with Grb2 exclusively through its SH3 domains. These results demonstrate a novel Grb2-p120cbl signaling complex in T cells, distinct from the previously analyzed Grb2-Sos complex. The association of p120cbl with ubiquitous signaling proteins strongly suggests a general signal transducing function for this enigmatic protooncogene with established leukemogenic potential but unknown physiological function.

Adaptor Proteins, Signal Transducing↗

PubMed1994

T-cell antigen CD28 interacts with the lipid kinase phosphatidylinositol 3-kinase by a cytoplasmic Tyr(P)-Met-Xaa-Met motif.

The T-cell antigen CD28 provides a costimulatory signal that is required for T-cell proliferation. T-cell receptor zeta/CD3 engagement without CD28 ligation leads to a state of nonresponsiveness/anergy, thereby implicating CD28 in the control of peripheral tolerance to foreign antigens or tumors. A key unresolved question has concerned the mechanism by which CD28 generates intracellular signals. Phosphatidylinositol 3-kinase (PI 3-kinase) is a lipid kinase with Src-homology 2 (SH2) domain(s) that binds to the platelet-derived growth factor receptor (PDGF-R), an interaction that is essential for signaling by growth factor. In this study, we demonstrate that CD28 binds to PI 3-kinase by means of a Y(P)MXM motif within its cytoplasmic tail. CD28-associated PI 3-kinase was detected by lipid kinase and HPLC analysis as well as by reconstitution experiments with baculoviral-expressed p85 subunit of PI 3-kinase. CD28 bound directly to the p85 subunit without the need for the associated p110 subunit. Site-directed mutagenesis and peptide competition analysis using Y(P)-MXM-containing peptides showed that PI 3-kinase bound to a Y(P)MXM motif within the CD28 cytoplasmic tail (residues 191-194). Mutation of the Y191 within the motif resulted in a complete loss of binding, while mutation of M194 caused partial loss of binding. Binding analysis showed that the CD28 Y(P)-MXM motif bound to the p85 C- and N-terminal SH2 domains with an affinity comparable to that observed for PDGF-R and insulin receptor substrate 1. In terms of signaling, CD28 ligation induced a dramatic increase in the recruitment and association of PI 3-kinase with the receptor. CD28 is likely to use PI 3-kinase as the second signal leading to T-cell proliferation, an event with implications for anergy and peripheral T-cell tolerance.

Amino Acid Sequence↗

PubMed1994

Microinjection of the SH2 domain of the 85-kilodalton subunit of phosphatidylinositol 3-kinase inhibits insulin-induced DNA synthesis and c-fos expression.

We have investigated the functional role of the SH2 domain of the 85-kDa subunit (p85) of the phosphatidylinositol 3-kinase in the insulin signal transduction pathway. Microinjection of a bacterial fusion protein containing the N-terminal SH2 domain of p85 inhibited insulin- and other growth factor-induced DNA synthesis by 90% and c-fos protein expression by 80% in insulin-responsive rat fibroblasts. The specificity of the fusion protein was examined by in vitro precipitation experiments, which showed that the SH2 domain of p85 can independently associate with both insulin receptor substrate 1 and the insulin receptor itself in the absence of detectable binding to other phosphoproteins. The microinjection results were confirmed through the use of an affinity-purified antibody directed against p85, which gave the same phenotype. Additional studies were carried out in another cell line expressing mutant insulin receptors which lack the cytoplasmic tyrosine residues with which p85 interacts. Microinjection of the SH2 domain fusion protein also inhibited insulin signaling in these cells, suggesting that association of p85 with insulin receptor substrate 1 is a key element in insulin-mediated cell cycle progression. In addition, coinjection of purified p21ras protein with the p85 fusion protein or the antibody restored DNA synthesis, suggesting that ras function is either downstream or independent of p85 SH2 domain interaction.

Animals↗

PubMed1994

Genetic analysis of a phosphatidylinositol 3-kinase SH2 domain reveals determinants of specificity.

Phosphatidylinositol 3-kinase is an important element in both normal and oncogenic signal transduction. Polyomavirus middle T antigen transforms cells in a manner depending on association of its tyrosine 315 phosphorylation site with Src homology 2 (SH2) domains on the p85 subunit of the phosphatidylinositol 3-kinase. Both nonselective and site-directed mutagenesis have been used to probe the interaction of middle T with the N-terminal SH2 domain of p85. Most of the 24 mutants obtained showed reduced middle T binding. However, mutations that showed increased binding were also found. Comparison of middle T binding to that of the platelet-derived growth factor receptor showed that some mutations altered the specificity of recognition by the SH2 domain. Mutations altering S-393, D-394, and P-395 were shown to affect the ability of the SH2 domain to select peptides from a degenerate phosphopeptide library. These results focus attention on the role of the EF loop in the SH2 domain in determining binding selectivity at the third position after the phosphotyrosine.

Antigens, Polyomavirus Transforming↗

PubMed1994

Physical and functional interactions between SH2 and SH3 domains of the Src family protein tyrosine kinase p59fyn.

The Src family protein tyrosine kinases participate in signalling through cell surface receptors that lack intrinsic tyrosine kinase domains. All nine members of this family possess adjacent Src homology (SH2 and SH3) domains, both of which are essential for repression of the enzymatic activity. The repression is mediated by binding between the SH2 domain and a C-terminal phosphotyrosine, and the SH3 domain is required for this interaction. However, the biochemical basis of functional SH2-SH3 interaction is unclear. Here, we demonstrate that when the SH2 and SH3 domains of p59fyn (Fyn) were present as adjacent domains in a single protein, binding of phosphotyrosyl peptides and proteins to the SH2 domain was enhanced, whereas binding of a subset of cellular polypeptide ligands to the SH3 domain was decreased. An interdomain communication was further revealed by occupancy with domain-specific peptide ligands: occupancy of the SH3 domain with a proline-rich peptide enhanced phosphotyrosine binding to the linked SH2 domain, and occupancy of the SH2 domain with phosphotyrosyl peptides enhanced binding of certain SH3-specific cellular polypeptides. Second, we demonstrate a direct binding between purified SH2 and SH3 domains of Fyn and Lck Src family kinases. Heterologous binding between SH2 and SH3 domains of closely related members of the Src family, namely, Fyn, Lck, and Src, was also observed. In contrast, Grb2, Crk, Abl, p85 phosphatidylinositol 3-kinase, and GTPase-activating protein SH2 domains showed lower or no binding to Fyn or Lck SH3 domains. SH2-SH3 binding did not require an intact phosphotyrosine binding pocket on the SH2 domain; however, perturbations of the SH2 domain induced by specific high-affinity phosphotyrosyl peptide binding abrogated binding of the SH3 domain. SH3-SH2 binding was observed in the presence of proline-rich peptides or when a point mutation (W119K) was introduced in the putative ligand-binding pouch of the Fyn SH3 domain, although these treatments completely abolished the binding to p85 phosphatidylinositol 3-kinase and other SH3-specific polypeptides. These biochemical SH2-SH3 interactions suggest novel mechanisms of regulating the enzymatic activity of Src kinases and their interactions with other proteins.

Amino Acid Sequence↗

PubMed1993

Granulocyte macrophage-colony stimulating factor stimulates both association and activation of phosphoinositide 3OH-kinase and src-related tyrosine kinase(s) in human myeloid derived cells.

The signalling pathways used by the GM-CSF receptor are currently unknown. Here we show that in human myeloid derived cells GM-CSF can stimulate; (i) the accumulation of PtdIns(3,4,5)P3; (ii) increases in p53/p56lyn and p62c-yes directed protein tyrosine kinase activities in anti-lyn and anti-c-yes antibody directed immunoprecipitates, respectively and; (iii) increases in phosphoinositide 3OH-kinase activity in antiphosphotyrosine, anti-p53/p56lyn and anti-p62c-yes antibody directed immunoprecipitates. These results suggest that GM-CSF can stimulate formation of protein tyrosine kinase co-ordinated signalling complexes, that contain p53/p56lyn, p62c-yes and an activated PtdInsP2 directed phosphoinositide 3OH-kinase, which can drive the accumulation of the putative second-messenger PtdIns(3,4,5)P3.

Cells, Cultured↗

PubMed1993

Effects of ioversol versus iothalamate on endothelin release and radiocontrast nephropathy.

RATIONALE AND OBJECTIVES: Certain radiocontrast agents, including iothalamate, iohexol, and ioxaglate, release the renal vasoconstrictor peptide endothelin from vascular endothelium in a way that might contribute to radiocontrast nephropathy. The effects of the nonionic, low osmolar agent, ioversol, on endothelin release and renal function are investigated. METHODS: Effects of ioversol were compared with equi-iodine doses of iothalamate when applied to cultured bovine aortic endothelial cells or injected into normal rats and rats preconditioned by uninephrectomy, salt depletion, and indomethacin (USIC) to develop radiocontrast nephropathy. RESULTS: In comparison with iothalamate, ioversol had a greatly reduced propensity to stimulate the release of endothelin, from cultured cells and when injected into anesthetized rats. Ioversol produced less renal vasoconstriction than did iothalamate, in control and in USIC rats, and the development of radiocontrast nephropathy, assessed by creatinine clearance and morphologic damage to the renal medulla, was largely avoided. CONCLUSIONS: These results strengthen the hypothesis that endothelin release induced by radiocontrast agents is correlated with their renal toxicity and therefore, may play a role in radiocontrast nephropathy.

Animals↗