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Query: EC:2.7.10.1 (
ERK
)
95,504
document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)
The
tyrosine kinase receptor
Ret is expressed in the ureteric bud and is required for normal renal development. Constitutive loss of Ret, its co-receptor gfralpha-1, or the ligand glial cell line-derived neurotrophic factor results in renal agenesis. Transgenic embryos that express a constitutively active form of Ret (Ret(MEN2B)) under the control of the dopamine-beta-hydroxylase (DbetaH) promoter develop profound neuroglial hyperplasia of their sympathetic ganglia and adrenal medullae. Embryos from two independent DbetaH-Ret(MEN2B)-transgenic lines exhibit renal malformations. In contrast with ret-/- embryos, renal maldevelopment in DbetaH-Ret(MEN2B)-transgenic embryos results from primary changes in sympathoadrenal organs extrinsic to the kidney. The ureteric bud invades the metanephric mesenchyme normally, but subsequent bud branching and nephrogenesis are retarded, resulting in severe renal hypoplasia. Ablation of sympathoadrenal precursors restores normal renal growth in vivo and in vitro. We postulate that disruption of renal development results because Ret(MEN2B) derived from the hyperplastic nervous tissue competes with endogenous renal Ret for gfralpha-1 or other signaling components. This hypothesis is supported by the observation that renal malformations, which do not normally occur in a transgenic line with low levels of DbetaH-Ret(MEN2B) expression, arise in a gdnf+/- background. However, renal maldevelopment was not recapitulated in kidneys that were co-cultured with explanted transgenic ganglia in vitro. Our observations illustrate a novel pathogenic mechanism for renal dysgenesis that may explain how putative activating mutations of the
RET
gene can produce a phenotype usually associated with
RET
deficiency.
...
PMID:Sympathoadrenal hyperplasia causes renal malformations in Ret(MEN2B)-transgenic mice. 1059 45
The neu (c-erbB-2) proto-oncogene encodes a
tyrosine kinase receptor
that is overexpressed in 20 to 30% of human breast tumors. Herein, cyclin D1 protein levels were increased in mammary tumors induced by overexpression of wild-type
Neu
or activating mutants of
Neu
in transgenic mice and in MCF7 cells overexpressing transforming
Neu
. Analyses of 12
Neu
mutants in MCF7 cells indicated important roles for specific C-terminal autophosphorylation sites and the extracellular domain in cyclin D1 promoter activation. Induction of cyclin D1 by NeuT involved Ras, Rac, Rho, extracellular signal-regulated kinase, c-Jun N-terminal kinase, and p38, but not phosphatidylinositol 3-kinase. NeuT induction of the cyclin D1 promoter required the E2F and Sp1 DNA binding sites and was inhibited by dominant negative E2F-1 or DP-1.
Neu
-induced transformation was inhibited by a cyclin D1 antisense or dominant negative E2F-1 construct in Rat-1 cells. Growth of NeuT-transformed mammary adenocarcinoma cells in nude mice was blocked by the cyclin D1 antisense construct. These results demonstrate that E2F-1 mediates a
Neu
-signaling cascade to cyclin D1 and identify cyclin D1 as a critical downstream target of neu-induced transformation.
...
PMID:Cyclin D1 is required for transformation by activated Neu and is induced through an E2F-dependent signaling pathway. 1061 Dec 46
The
MET
proto-oncogene, encoding the
tyrosine kinase receptor
for HGF, controls genetic programs leading to cell growth, invasiveness, and protection from apoptosis. Recently,
MET
mutations have been identified in hereditary and sporadic forms of papillary renal carcinoma (PRC). Introduction of different naturally occurring mutations into the
MET
cDNA results in the acquisition of distinct biochemical and biological properties of transfected cells. Some mutations result in a high increase in tyrosine kinase activity and confer transforming ability in focus forming assays. These mutants hyperactivate the Ras signaling pathway. Other mutations are devoid of transforming potential but are effective in inducing protection from apoptosis and sustaining anchorage-independent growth. These Met(PRC) receptors interact more efficiently with the intracellular transducer Pi3Kinase. The reported results show that
MET
(PRC) mutations can be responsible for malignant transformation through different mechanisms, either by increasing the growth ability of cells or by protecting cells from apoptosis and allowing accumulation of other genetic lesions.-Giordano, S., Maffe, A., Williams, T. A., Artigiani, S., Gual, P., Bardelli, A., Basilico, C., Michieli, P., Comoglio, P. M. Different point mutations in the met oncogene elicit distinct biological properties.
...
PMID:Different point mutations in the met oncogene elicit distinct biological properties. 1065 96
The hallmark of the 8p12 stem cell myeloproliferative disorder (MPD) is the disruption of the
FGFR1
gene, which encodes a
tyrosine kinase receptor
for members of the fibroblast growth factor family.
FGFR1
can be fused to at least 3 partner genes at chromosomal regions 6q27, 9q33, or 13q12. We report here the cloning of the t(8;9)(p12;q33) and the detection of a novel fusion betweenFGFR1 and the CEP110 gene, which codes for a novel centrosome-associated protein with a unique cell-cycle distribution. CEP110 is widely expressed at various levels in different tissues and is predicted to encode a 994-amino acid coiled-coil protein with 4 consensus leucine zippers [L-X(6)-L-X(6)-L-X(6)-L]. Both reciprocal fusion transcripts are expressed in the patient's cells. The CEP110-
FGFR1
fusion protein encodes an aberrant tyrosine kinase of circa 150-kd, which retains most of CEP110 with the leucine zipper motifs and the catalytic domain of
FGFR1
. Transient expression studies show that the CEP110-FGFR1 protein has a constitutive kinase activity and is located within the cell cytoplasm. (Blood. 2000;95:1788-1796)
...
PMID:FGFR1 is fused to the centrosome-associated protein CEP110 in the 8p12 stem cell myeloproliferative disorder with t(8;9)(p12;q33). 1068 39
A metastatic cancer develops by accumulation of mutations in genes that control growth, survival and spreading. The latter genes have not yet been identified. In lymph node metastases of head and neck squamous cell carcinomas (HNSCC), we found mutations in the
MET
oncogene, which encodes the
tyrosine kinase receptor
for Scatter Factor, a cytokine that stimulates epithelial cell motility and invasiveness during embryogenesis and tissue remodeling. We identified two somatic mutations: the Y1230C, known as a
MET
germline mutation which predisposes to hereditary renal cell carcinoma, and the Y1235D that is novel and changes a critical tyrosine, known to regulate
MET
kinase activity. The mutated
MET
receptors are constitutively active and confer an invasive phenotype to transfected cells. Interestingly, cells carrying the
MET
mutations are selected during metastatic spread: transcripts of the mutant alleles are highly represented in metastases, but barely detectable in primary tumors. These data indicate that cells expressing mutant
MET
undergo clonal expansion during HNSCC progression and suggest that
MET
might be one of the long sought oncogenes controlling progression of primary cancers to metastasis.
...
PMID:Somatic mutations of the MET oncogene are selected during metastatic spread of human HNSC carcinomas. 1073 14
Vasculogenesis and angiogenesis are the mechanisms responsible for the development of the blood vessels. Angiogenesis refers to the formation of capillaries from pre-existing vessels in the embryo and adult organism, while vasculogenesis is the development of new blood vessels from the differentiation of endothelial precursors (angioblasts) in situ. Vascular endothelial growth factor (VEGF) family members are major mediators of vasculogenesis and angiogenesis both during development and in pathological conditions. VEGF has a variety of effects on vascular endothelium, including the ability to promote endothelial cell viability, mitogenesis, chemotaxis, and vascular permeability. It mediates its activity mainly via two tyrosine kinase receptors, VEGFR-1 (flt-1) and VEGFR-2 (flk-1/
KDR
), although other receptors, such as neuropilin-1 and -2, can also bind VEGF. Another
tyrosine kinase receptor
, VEGFR-3 (flt-4) binds VEGF-C and VEGF-D and is more important in the development of lymphatic vessels. While the functional effects of VEGF on endothelial cells has been well studied, not as much is known about VEGF signaling. This review summarizes the different pathways known to be involved in VEGF signal transduction and the biological responses triggered by the VEGF signaling cascade.
...
PMID:Signaling pathways induced by vascular endothelial growth factor (review). 1076 46
ALK
(
anaplastic lymphoma kinase
) is a
tyrosine kinase receptor
, expressed as part of the chimeric NPM-
ALK
protein, in anaplastic large cell lymphomas (ALCLs) exhibiting the t(2;5)(p23;q35) translocation. As a result of this translocation, the NPM (nucleophosmin) gene is fused to the portion of the
ALK
gene encoding its intracytoplasmic segment. In normal mouse tissues, mRNA encoding the Alk receptor has been found only in neural cells, suggesting involvement of this receptor in the development of the nervous system. The purpose of the present study was to examine the presence of
ALK
transcripts and protein in normal human tissues and a variety of cell lines and human tumors. Emphasis was placed on neuroblastomas because other tyrosine kinase receptors are expressed in human neuroblastomas. Fifty-six cell lines, including 29 lines of neural origin, and lymphoid and nonlymphoid tissue specimens, including 24 neuroblastomas, were investigated for
ALK
expression, using reverse transcriptase-polymerase chain reaction, Western blotting, and immunohistochemistry. The results confirmed that mRNA encoding
ALK
protein was not detectable in any normal or neoplastic hematopoietic tissue tested, except for t(2;5)-positive ALCL. The salient finding was that 13 of the 29 cell lines of neural origin and 22 of 24 neuroblastomas were found to express
ALK
transcripts and
ALK
protein. However, no correlation was evident between any known prognostic factors and the level of
ALK
expression.
...
PMID:Expression of the ALK tyrosine kinase gene in neuroblastoma. 1079 82
Glial cell line-derived neurotrophic factor (GDNF) is expressed in many neuronal and non-neuronal tissues during development as well as in adult animals. GDNF signaling is mediated through a two-component system consisting of the so called GDNF receptor-alfa (GFRalpha1) which binds to GDNF. Thereafter this complex binds to and activates the
tyrosine kinase receptor
RET
. In this work, for the first time, we have characterized the expression of both GDNF and
RET
in the anterior pituitary. First of all, RT-PCR analysis, Western blot and immunohistochemistry of the whole anterior pituitary showed that GDNF, GFRalpha1 and
RET
are expressed in this gland. Following double-immunofluorescence of consecutive sections we found GDNF immunoreactivity in most cell types, and it was most abundant in corticotrophs (55%), LH (59%) and FSH-producing cells (81%). In contrast, while the majority of somatotrophs (87%) were stained for
RET
, no positive immunostaining could be detected in other cell types. Taken together, this data indicate that gonadotrophs and corticotrophs are the main source of GDNF synthesized in the anterior pituitary and that the somatotrophs appears to be their target cell. This study provides direct morphological evidences that GDNF may well be acting in a paracrine-like fashion in the regulation of somatotroph cell growth and/or cell function.
...
PMID:GDNF and RET-gene expression in anterior pituitary-cell types. 1080
Vascular endothelial growth factor (VEGF)-Flk-1/
KDR
tyrosine kinase signaling pathway plays a pivotal role in tumor angiogenesis. Targeting this angiogenic signaling pathway presents a promising alternative for the treatment of neoplasms. However, recent experimental and clinical studies have suggested that VEGF-Flk-1/
KDR
activity is unevenly distributed throughout the tumor microvasculature. To further evaluate this phenomenon, the regional differences in VEGF-Flk-1/
KDR
signaling activities in vivo were studied using intravital fluorescence videomicroscopy in an experimental murine brain tumor model. Regional VEGF-Flk-1/
KDR
was assessed using the small molecule inhibitor SU5416, which selectively inhibits the
tyrosine kinase receptor
Flk-1. C(6) glioblastoma cells were implanted into the dorsal skinfold chamber preparation of nude mice. The process of tumor vascularization was repeatedly assessed over 22 days. SU5416 treatment resulted in a significant reduction in tumor vascular density (p<0.05). Regional microvascular evaluation indicated that the magnitude of this antiangiogenic effect was pronounced in the more angiogenic and better vascularized peritumoral areas than in the intratumoral areas of the tumor microvasculature. These results demonstrate regional differences in Flk-1 activity in vivo that may have significant impact on the susceptibility of tumors to compounds that target VEGF-Flk-1/
KDR
. This finding should be considered in upcoming clinical trials targeting individual signal transduction systems in cancer patients.
...
PMID:Measuring VEGF-Flk-1 activity and consequences of VEGF-Flk-1 targeting in vivo using intravital microscopy: clinical applications. 1080 86
Heparan sulfate-regulated transmembrane
tyrosine kinase receptor
FGFR4
is the major FGFR isotype in mature hepatocytes. Fibroblast growth factor has been implicated in the definition of liver from foregut endoderm where
FGFR4
is expressed and stimulation of hepatocyte DNA synthesis in vitro. Here we show that livers of mice lacking
FGFR4
exhibited normal morphology and regenerated normally in response to partial hepatectomy. However, the
FGFR4
(-/-) mice exhibited depleted gallbladders, an elevated bile acid pool and elevated excretion of bile acids. Cholesterol- and bile acid-controlled liver cholesterol 7alpha-hydroxylase, the limiting enzyme for bile acid synthesis, was elevated, unresponsive to dietary cholesterol, but repressed normally by dietary cholate. Expression pattern and cholate-dependent, cholesterol-induced hepatomegaly in the
FGFR4
(-/-) mice suggested that activation of receptor interacting protein 140, a co-repressor of feed-forward activator liver X receptor alpha, may mediate the negative regulation of cholesterol- and bile acid-controlled liver cholesterol 7alpha-hydroxylase transcription by
FGFR4
and cholate. The results demonstrate that transmembrane sensors interface with metabolite-controlled transcription networks and suggest that pericellular matrix-controlled liver
FGFR4
in particular may ensure adequate cholesterol for cell structures and signal transduction.
...
PMID:Elevated cholesterol metabolism and bile acid synthesis in mice lacking membrane tyrosine kinase receptor FGFR4. 1080 80
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