Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Genes, src”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,243 records · Page 69Linked to original sources
PubMed1999

Metabolic differences between genetically lean and fat chickens are partly attributed to the alteration of insulin signaling in liver.

Insulin signaling [tyrosine phosphorylation of insulin receptor (IR), insulin receptor substrate-1 (IRS-1), Src homology and collagen protein (Shc) and phosphatidyl inositol 3'-kinase activity (PI 3'-kinase)] was studied in the liver and thigh muscles of fat (FL) and lean (LL) chickens. These lines result from a divergent selection on abdominal fat pad size. The divergence is of metabolic origin. Extreme nutritional states were studied (fed, 48-h starved and 30-min refed). Such conditions significantly altered insulin signaling in chicken liver, but surprisingly not in the muscle (except the phosphorylation of Shc in the refed state). No major differences that could account for this divergence were found in muscle. Liver IR number and Shc protein did not differ between genotypes. Liver IRS-1 (protein and messenger) was lower in the fed state and higher in the starved state in FL compared to that in LL chickens. In the fed state, tyrosine phosphorylation of liver IR, IRS-1 and Shc action was higher in FL than in LL chickens that in the absence of insulin resistance rely on higher plasma insulin levels. In the starved state, phosphorylation of liver IR was lower, but the phosphorylation of IR and IRS-1 were higher in LL than in FL chickens, most likely in response to higher plasma glucose and insulin in the lean genotype. In the refed state, the phosphorylation of liver IR and IRS-1 did not differ between genotypes despite significantly lower plasma insulin in FL chickens. Finally, PI 3'-kinase was not affected by the genotype. A significant activation of early steps of insulin signaling in liver of fed FL chickens may at least partly account for their increased liver lipogenesis and ultimately their fattening.

Animals↗
PubMed1995

A conserved amino-terminal Shc domain binds to phosphotyrosine motifs in activated receptors and phosphopeptides.

BACKGROUND: Signal transduction by growth factor receptor protein-tyrosine kinases is generally initiated by autophosphorylation on tyrosine residues following ligand binding. Phosphotyrosines within activated receptors form binding sites for the Src homology 2 (SH2) domains of cytoplasmic signalling proteins. One such protein, Shc, is tyrosine phosphorylated in response to a large number of growth factors and cytokines. Phosphorylation of Shc on tyrosine residue Y317 allows binding to the SH2 domain of Grb2, and hence stimulation of the Ras pathway. Shc is therefore implicated as an adaptor protein able to couple normal and oncogenic protein-tyrosine kinases to Ras activation. Shc itself contains an SH2 domain at its carboxyl terminus, but the function of the amino-terminal half of the protein is unknown. RESULTS: We have found that the Shc amino-terminal region binds to a number of tyrosine-phosphorylated proteins in v-src-transformed cells. This domain also bound directly to the activated epidermal growth factor (EGF) receptor. A phosphotyrosine (pY)-containing peptide modeled after the Shc-binding site in polyoma middle T antigen (LLSNPTpYSVMRSK) was able to compete efficiently with the activated EGF receptor for binding to the Shc amino terminus. This competition was dependent on phosphorylation of the tyrosine residue within the peptide, and was abrogated by deletion of the leucine residue at position -5. The Shc amino-terminal domain also bound to the autophosphorylated nerve growth factor receptor (Trk), but bound significantly less well to a mutant receptor in which tyrosine Y490 in the receptor's Shc-binding site had been substituted by phenylalanine. CONCLUSION: These data implicate the amino-terminal region of Shc in binding to activated receptors and other tyrosine-phosphorylated proteins. Binding appears to be specific for phosphorylated tyrosine residues within the sequence NPXpY, which is conserved in many Shc-binding sites. The Shc amino-terminal region bears only very limited sequence identify to known SH2 domains, suggesting that it represents a new class of phosphotyrosine-binding modules. Consistent with this view, the amino-terminal Shc domain is highly conserved in a Drosophila Shc homologue. Binding of Shc to activated receptors through its amino terminus could leave the carboxy-terminal SH2 domain free for other interactions. In this way, Shc may function as an adaptor protein to bring two tyrosine-phosphorylated proteins together.

3T3 Cells↗
PubMed1992

Presence of SH2 domains of phospholipase C gamma 1 enhances substrate phosphorylation by increasing the affinity toward the epidermal growth factor receptor.

src homology region 2 and 3 (SH2 and SH3) domains are conserved noncatalytic regions originally described in cytoplasmic tyrosine kinases and subsequently identified in phospholipase C gamma 1 (PLC gamma 1), GTPase-activating protein of ras, and other signaling proteins. Although numerous studies indicate that SH2 domains promote protein-protein interactions by specific binding to tyrosine phosphorylated proteins, the function of SH3 domains is not known. The SH2 domain of PLC gamma 1 binds to certain tyrosine-phosphorylated growth factor receptors, and following phosphorylation on Tyr783 the enzymatic activity of PLC gamma 1 is enhanced, leading to phosphatidylinositol hydrolysis. To determine the functional role of the SH2 domain(s) on substrate phosphorylation in quantitative terms, we have expressed in Escherichia coli PLC gamma 1 constructs encoding the region containing Tyr783 and Tyr771, their two flanking SH2 domains and the SH3 domain, and five different deletion mutants of this region. These six proteins were purified and subjected to quantitative phosphorylation by the epidermal growth factor receptor (EGFR). Analysis of the kinetics of substrate phosphorylation revealed similar Vmax for the phosphorylation of the various mutant proteins. However, the affinity was enhanced for substrates containing SH2 domains: from S0.5 (average apparent Km) of 110 microM to S0.5 of 20 microM with the addition of a single SH2 domain and S0.5 of 3-4 microM for mutants containing two SH2 domains. The presence of the SH3 domain did not influence the apparent Km of substrate phosphorylation. These results demonstrate that the presence of the SH2 domain in PLC gamma 1 lowers the apparent Km (increases the affinity) of substrate phosphorylation by the EGFR, thereby facilitating PLC gamma 1 phosphorylation and activation.

Binding Sites↗
PubMed1994

Down-regulation of membrane immunoglobulin-associated proteins, MB-1, B29 and Lyn, in AIDS-lymphomas and related conditions.

B-lymphocytes infected with Epstein-Barr virus (EBV) can proliferate in immunocompromised hosts to form lymphomas (MLs). Similar MLs are produced in mice with severe combined immune deficiency (SCID) by transfusion of human lymphocytes infected with EBV (SCID-EBV-positive BML). Mb-1 and B29 are recently found transmembrane proteins associated with membrane immunoglobulins (mIg) on the surface of B cells. Lyn is a src family gene product expressed in B cells submembranously, in association with mIg, possibly through Mb-1/B29 heterodimer. These mIg-associated proteins (Mb-1, B29 and Lyn) are known to mediate antigenic stimulation through mIgs. We noted recently that Lyn is decreased selectively in around a half of SCID-EBV-positive BMLs. We extended this line of investigation to other mIg-associated proteins. Five acquired immunodeficiency syndrome (AIDS)-MLs and ten SCID-EBV-positive BMLs were first analysed by immunohistochemistry for the expression of Mb-1, B29 and Lyn. It was found that in AIDS-MLs, all the mIg-associated proteins were heavily down-regulated. In SCID-EBV-positive BMLs, Mb-1 was down regulated in six of ten, B29 in nine of ten and Lyn in six of ten, whereas no down-regulation was noted in eight EBV-free B MLs that were also maintained in SCID mice. An additional flow-cytometric study of two SCID-EBV-positive and two EBV-negative BMLs showed similar down-regulation in the former cases exclusively. Whereas mIg was also decreased in three of five SCID-EBV positive BMLs, it did not necessarily match the decrease of mIg-associated proteins, which contrasts with the recent finding that mIgs coexist with Mb-1 or B29. Some EBV-encoded proteins may activate host molecules located downwardly; this, in turn, may lead to the suppression of these upwardly-located mIg-associated proteins.

Adult↗
PubMed1992

Reduced tumorigenicity of fibrosarcomas which constitutively generate IL-1 alpha either spontaneously or following IL-1 alpha gene transfer.

Interleukin-1 (IL-1) is a major immunoregulatory/proinflammatory cytokine which also affects fibroblast proliferation and function and therefore it was of interest to investigate whether its constitutive expression influences the in vivo tumorigenic potential of transformed fibroblastoid cell lines. Here we report on a strong correlation between the constitutive expression of IL-1 alpha and reduced tumorigenicity, using various series of oncogene-transformed NIH/3T3-derived cell lines which produce the cytokine spontaneously or upon gene transfer, following transfection with the IL-1 alpha cDNA. Reduced tumorigenicity of the constitutive IL-1 alpha producing cell lines was manifested either by inability to grow in animals or by regressions of initially growing tumors, within 2 to 3 weeks from cell inoculation. In contrast, mice inoculated with non-IL-1-producing cell lines developed progressive tumors which ultimately killed the animals. Clones obtained from a non-IL-1-producing met-transformed cell line shifted from a progressive to a regressive phenotype, following transfection with an IL-1 alpha-encoding gene, inserted into an appropriate expression vector, resulting in constitutive expression of the cytokine. The effects of constitutive IL-1 expression on tumor development were observed both in histocompatible (NFS/N) and partially allogeneic (BALB/c) mice; however, they were more pronounced in the allogeneic environment. Fibrosarcomas which are non-IL-1 producers induced progressive tumors in both strains of mice at the same growth rate. The differences between the growth characteristics of the fibrosarcomas in histocompatible vs. partially allogenic mice suggest that IL-1 exerts adjuvant-like effects which increase the immunogenicity of tumor-cell antigens, and they also argue against the possibility that an IL-1-mediated local non-specific inflammatory response is the major effector mechanism of tumor rejection. Indeed, in subsequent studies we shall report on the importance of specific cellular immune responses, especially cytotoxic T lymphocytes (CTLs), in the eradication of constitutive IL-1-producing fibrosarcomas. Thus, our findings may serve as the basis for novel immunotherapy strategies aimed at the induction of IL-1 expression by cells comprising the neoplasm or alternatively by local application of the cytokine in the vicinity of the tumor.

Animals↗
PubMed1993

Cellular and in vivo characterization of the MCR rat mammary tumor model.

The slowly growing, transplantable MCR-83 rat mammary tumor is estrogen-dependent and non-metastasizing. A rapidly growing, estrogen-independent, metastasizing subline (MCR-86) was subsequently isolated in vivo. We have established and characterized cell lines from both MCR rat mammary tumors. MCR cell lines and tumors were studied in vivo and in vitro. Analysis of DNA from tumors and cell lines showed that mutations had not occurred in codons 12, 13 and 61 of the Ha-ras and Ki-ras genes. Additionally, dominant transforming activity could not be detected by DNA transfection using NIH 3T3 focus-forming assay. No gene amplification was detected for either the EGF-receptor or c-erbB-2 genes. Differences in the tyrosine phosphorylation patterns were found between the 2 MCR cell lines. Addition of serum to starved cells resulted in the tyrosine phosphorylation of a 120-kDa protein, which was elevated in the MCR-86. The lack of ras activation in the MCR tumors differentiates this model from the widely studied, chemically induced rodent mammary tumors. In addition, the differences in the cellular phosphotyrosine patterns between MCR-83 and MCR-86 suggests the occurrence of alterations in signalling pathways that involve tyrosine protein kinases.

3T3 Cells↗
PubMed1995

3BP-1, an SH3 domain binding protein, has GAP activity for Rac and inhibits growth factor-induced membrane ruffling in fibroblasts.

The SH3 binding protein, 3BP-1, was originally cloned as a partial cDNA from an expression library using the Abl SH3 domain as a probe. In addition to an SH3 binding domain, 3BP-1 displayed homology to a class of GTPase activating proteins (GAPs) active against Rac and Rho proteins. We report here a full length cDNA of 3BP-1 which extends the homology to GAP proteins previously noted. 3BP-1 functions in vitro as a GAP with a specificity for Rac-related G proteins. Microinjection of the 3BP-1 protein into serum-starved fibroblasts produces an inhibition of platelet-derived growth factor (PDGF)-induced membrane ruffling mediated by Rac. Co-injection of 3BP-1 with an activated Rac mutant that is unresponsive to GAPs, counter-acts this inhibition. 3BP-1 does not show in vitro activity towards Rho and, in agreement with this finding, microinjection of 3BP-1 into fibroblasts has no effect on lysophosphatidic acid (LPA)-induced stress fiber assembly mediated by Rho. Thus 3BP-1 is a new and specific Rac GAP that can act in cells to counter Rac-mediated membrane ruffling. How its SH3 binding site interacts with its GAP activity remains to be understood.

3T3 Cells↗
PubMed2006

Biology of colorectal liver metastases: A review.

Metastatic growth is a selective, non-random process, which in the case of colorectal cancer, frequently occurs in the liver and is the major cause of cancer related death in these patients. This review summarises attempts to find biological and molecular markers of metastasis and their role in establishment of secondary tumours. Recent evidence suggests that liver metastases are phenotypically different to the primary from which they were derived and thus represent a separate disease entity.

Apoptosis↗
PubMed2006

Screening of genetic and expression alterations of SRC1 gene in prostate cancer.

BACKGROUND: Genetic alterations of the SRC1 gene have not been thoroughly studied in prostate cancer. MATERIALS AND METHODS: Five prostate cancer cell lines and 32 xenografts were screened for mutations and gene copy number alterations. Subsequently, frequencies of detected sequence variations were further analyzed in 44 clinical prostate cancers, 6 benign prostate hyperplasias, and 48 normal controls. Finally, the protein expression of SRC1 in 254 clinical prostate tumors was investigated. RESULTS: Three non-recurrent sequence variations, and one single nucleotide polymorphism in the coding region of SRC1, as well as one case of SRC1 gene amplification were found. The protein expression of SRC1 was higher in androgen ablation resistant than untreated prostate carcinomas, but the difference was not statistically significant (P = 0.0796). CONCLUSIONS: Genetic alterations of SRC1 are rare in prostate cancer. The nuclear protein accumulation of SRC1 seems to be mildly increased in androgen ablation resistant prostate cancers. .

Androgen Antagonists↗
PubMed1993

Identification of novel pleckstrin homology (PH) domains provides a hypothesis for PH domain function.

Pleckstrin homology (PH) domains are difficult to find in protein sequence databases with widely used computer programs. A simple program developed to overcome this difficulty identified three proteins containing previously unrecognized PH domains; the beta-adrenergic receptor kinase (beta-ARK), the tecA protein kinase and the insulin receptor substrate protein IRS-1. The region of beta-ARK containing the novel PH domain coincides with that previously shown to bind the beta gamma subunits of trimeric G-proteins, suggesting a general hypothesis for PH domain function. PH domains were then found at the N-termini of the tecA homologues Btk and itk. In line with the hypothesis a point mutation in the PH domain of Btk is associated with defects in signal transduction.

Amino Acid Sequence↗
PubMed1994

Cloning of the cDNA for the deleted syk kinase homologous to ZAP-70 from human basophilic leukemia cell line (KU812).

Syk kinase is one of the protein tyrosine kinases and forms a family with ZAP-70. We isolated two different sized cDNA clones of syk (Syk11 and Syk41) from a cDNA library of human KU812 (human basophilic leukemia cell line). The obtained two clones carried different messages, that Syk41 had a 69 bp-long insertion between the SH2 domain and the kinase domain compared with Syk11. Alignment of the two human syk predicted polypeptides with those of the porcine syk and ZAP-70 revealed that human syk was 5 amino acid longer than the porcine syk at the N-termini and that the insertion of the 23 amino acid found in Syk41 was present in the porcine syk and absent in ZAP-70. Reverse transcribed polymerase chain reaction targeting this region showed that both forms of the polyA RNA were expressed in Jurkat cells, human peripheral leukocytes and also KU812 cells and that the inserted form was dominant.

Amino Acid Sequence↗
PubMed1996

Deregulated expression and function of CFTR and Cl- secretion after activation of the Ras and Src/PyMT pathways in Caco-2 cells.

We evaluated the role of the activated Ras and Src/PyMT (Polyoma Middle T) signaling pathways on the expression of the cystic fibrosis transmembrane conductance regulator (CFTR) in human colonic Caco-2 cell lines. Control vector-transfected Caco-2 cell monolayer preparations (Caco-2-H) responded to forskolin with an increase in short circuit current (Isc) mediated by CFTR. Furthermore, Caco-2-H cells responded to ATP, a reported stimulator of intracellular Ca2+ (Cai2+), and a potential source of adenosine-mediated elevation of cAMP. In contrast, Caco-2 cells transfected with PyMT (Caco-2-MT), expressing high levels of PKC, showed no sustained Isc response to forskolin or ATP. Pretreatment of Caco-2-MT cells with 2.5 microM phorbol 12-myristate 13-acetate (PMA) for 24 hr. effectively down-regulated PKC activity and restored expression of CFTR mRNA but failed to re-establish functional CFTR. These data suggest that, stable up-regulation of PKC alpha, consequent to activation of the Ras or Src/PyMT pathways, leads to an absence of CFTR expression and Cl- secretion mediated by either cAMP or Cai2+. Moreover, Cl- secretion in the colonic Caco-2 epithelial cell line is mediated primarily by CFTR and an alternate Cai(2+)-activated Cl- channel is not functional in these cells.

Adenosine Triphosphate↗
PubMed1993

Gene structure and expression in colorectal cancer.

Colorectal cancer provides a unique model for the study of molecular changes that are associated with tumorigenesis. The cancer evolves as an apparent ordered sequence from a benign to a malignant lesion in histopathological recognizable stages. Since it is relatively easy to isolate tissue representing each of these stages, studies of molecular events associated with tumor progression are feasible. Such studies have shown that multiple changes in gene structure, expression and activity occur during tumorigenesis.

Adenocarcinoma↗
PubMed1993

New patterns of bulk DNA repair in ultraviolet irradiated mouse embryo carcinoma cells following differentiation.

Mouse embryocarcinoma stem cells differentiate in culture, given the appropriate induction. We examined whether these cells could provide information about the regulation of nucleotide excision repair in relation to differentiation by measuring the rate-limiting incision step, the removal of cyclobutane dimers and (6-4) photoproducts from the genome as a whole and the effect of the bacteriophage T4 endonuclease (denV) gene on repair in differentiated cells. It was found that differentiation is accompanied by a marked decline in the early incision ability after UV irradiation (sixfold for P19, fourfold for PCC7 and twofold for F9), and we measured, in parallel, the loss of two common UV photoproducts [cyclobutane dimers and (6-4) photoproducts] from P19 cells. After differentiation, the excellent overall cyclobutane dimer repair capacity of proliferating cells (84% removal in 24 h) is lost (no removal in 24 h), while removal of (6-4) photoproducts, although normal at 24 h (94%), is much slower than in undifferentiated P19 at 3 h (no removal versus 64%). The presence of the denV gene greatly stimulates the repair of cyclobutane dimers in undifferentiated P19 cells (94% removal at 3 h versus 40%) and also in differentiated cells (50% removal at 24 h versus no removal). The denV gene also stimulates the early repair of (6-4) photoproducts in both differentiated and undifferentiated cells.

Animals↗
PubMed1992

Protein-tyrosine kinase activity of alternate protein products of the Drosophila Dsrc28C locus.

The Dsrc28C gene is a unique member of the extensive tyrosine kinase family. Two proteins, p66Dsrc28C and p55Dsrc28C, are encoded by the gene. Each contains a highly conserved tyrosine kinase domain and each lacks the usual amino-terminal myristylation signal. The protein-tyrosine kinase activity of the two proteins was investigated through a recombinant baculovirus expression system. p66Dsrc28C expressed from a recombinant baculovirus phosphorylated a large number of Sf9 cell proteins on tyrosine. A group of proteins of approximately 100 kDa were the preferred substrates. No evidence of p66Dsrc28C autophosphorylation was found. In contrast to p66Dsrc28C, p55Dsrc28C did not exhibit protein-tyrosine kinase activity when expressed from a recombinant baculovirus. A deletion derivative of p66Dsrc28C lacking the SH3 and SH2 domains also failed to phosphorylate Sf9 cell proteins. These results suggest that the protein-tyrosine kinase activity of Dsrc28C proteins is tightly regulated.

Animals↗