Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

---

Query: EC:2.7.10.1 (ERK)
95,504 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Bowel dysmotility in association with hypoganglionosis remains unexplained. The proto-oncogene c-kit encodes a transmembrane tyrosine kinase receptor, and the c-kit protein-product (C-KIT) positive cells in the mammalian gut are responsible for intestinal pacemaker activity. The authors examined the localization of intestinal pacemaker cells in the muscle layers of a patient with colonic hypoganglionosis, using an antihuman C-KIT serum. In the normoganglionic ileum, many C-KIT immunoreactivity positive (C-KIT-IR+) cells were present in the muscle layers. In contrast, there were no C-KIT-IR+ cells in the muscle layers of the hypoganglionic colon. These findings suggest that a lack of c-kit expression may be responsible for the autonomic gut dysmotility in hypoganglionic bowels.
...
PMID:Localization of intestinal pacemaker cells and synapses in the muscle layers of a patient with colonic hypoganglionosis. 880 19

Hirschsprung disease (HSCR), or congenital aganglionic megacolon, is the most common cause of congenital bowel obstruction with an incidence of 1 in 5000 live births. HSCR may be inherited as a single gene disorder with reduced penetrance or as a multigenic trait. HSCR mutations have been identified in the RET receptor tyrosine kinase, endothelin-B receptor (EDNRB) and its physiological ligand, endothelin 3 (EDN3). Although RET's ligand has remained elusive, it is expected to be an extracellular neurotrophic molecule expressed in the developing gut and kidney mesenchyme, based on the phenotypes of intestinal aganglionosis and renal agenesis observed in homozygous RET knockout (Ret -/-) mice. The glial cell line-derived neurotrophic factor (GDNF) is such a molecule. Recently, mice carrying two null alleles for Gdnf were shown to exhibit phenotypes remarkably similar to Ret-/- animals. We screened 106 unrelated HSCR patients for mutations in GDNF by direct sequencing. We identified one familial mutation in a HSCR patient with a known de novo RET mutation and malrotation of the gut. No haplotype sharing was evident in any of 36 HSCR kindreds typed for microsatellite markers surrounding GDNF on human chromosome 5p. Our data suggest that GDNF is a minor contributor to human HSCR susceptibility and that loss of its function in enteric neurogenesis may be compensated for by other neurotrophic factors or via other pathways. However, it may be that in rare instances, RET and GDNF mutations act in concert to produce an enteric phenotype.
...
PMID:Germline mutations in glial cell line-derived neurotrophic factor (GDNF) and RET in a Hirschsprung disease patient. 889 68

Hirschsprung disease (HSCR) is a common congenital abnormality characterized by absence of the enteric ganglia in the hind gut. In 10-40% of HSCR cases, mutations of the RET receptor tyrosine kinase have been found. The recent identification of a multimeric RET ligand/receptor complex suggested that mutations of genes encoding other components of this complex might also occur in HSCR. To investigate this role, we examined the gene for glial cell line-derived neurotrophic factor (GDNF), the circulating ligand of the RET receptor complex, for mutations in a panel of sporadic and familial HSCR. We identified GDNF sequence variants in 2/36 HSCR patients. The first of these was a conservative change which did not affect the GDNF protein sequence. The second variant was a de novo missense mutation in a family with no history of HSCR and without mutation of the RET gene. Thus, our data are consistent with a causative role for GDNF mutations in some HSCR cases.
...
PMID:De novo mutation of GDNF, ligand for the RET/GDNFR-alpha receptor complex, in Hirschsprung disease. 896 58

The RET (recombined in transfection) gene encodes a receptor tyrosine kinase homolog involved in innervation of the gut and renal development. A chimeric epidermal growth factor receptor (EGFR)/RET receptor was constructed which contained the extracellular and transmembrane domains of the EGF receptor fused to the intracellular domain of RET. This construct was expressed in NIH 3T3 cells, and the functional properties of the receptor were characterized and compared with those of the wild type EGF receptor. Whereas the EGF receptor exhibited both high and low affinity binding sites for 125I-EGF, the EGFR/RET chimera exhibited only low affinity binding of 125I-EGF. The chimera was able to internalize EGF more rapidly than the wild type EGF receptor and recycled to the cell surface at twice the rate of the EGF receptor. Pulse-chase experiments indicated that EGF stimulated the degradation of the wild type EGF receptor but had no effect on the rate of degradation of the EGFR/RET receptor. The combination of increased recycling and decreased degradation resulted in the relatively inefficient down-regulation of the EGFR/RET chimera. Incubation of cells expressing the wild type EGF receptor with phorbol 12-myristate 13-acetate led to a reduction in 125I-EGF binding and a loss in EGF-stimulated tyrosine phosphorylation. However, phorbol 12-myristate 13-acetate treatment had only a limited effect on EGF binding and EGF-stimulated tyrosine kinase activity in cells expressing EGFR/RET chimeras. These findings suggest that the ret tyrosine kinase is not regulated by many of the common mechanisms used to terminate signaling via growth factor receptors. Such persistent activation of the Ret tyrosine kinase may be relevant to the physiological function of Ret in cells that normally express this growth factor receptor.
...
PMID:Functional characterization of an epidermal growth factor receptor/RET chimera. 899 23

Because SRS identifies 90% of hepatic metastatic disease and the addition of other studies (ultrasonography, C.T. MRI, and selective mesenteric angiography) identities only 4% more, the identification of a primary lesion with SRS obviates for the most part the use of further investigations. If SRS is negative, additional studies should only be undertaken if surgery is contemplated. Because SRS may only localize 60%-70% of primary gut NETs, an additional 10%-15% may be identified by undertaking additional studies. The most sensitive test, STIR-MRI, should be undertaken next, but because it is not widely available, pancreatic protocol CT scan is almost as effective in identification of a primary lesion. If a primary gastrinoma cannot be identified by SRS or STIR-MRI, endoscopic ultrasonography should be undertaken because duodenal gastrinomas are often minute and multicentric. A similar strategy applies for insulinomas because up to 40% cannot be located by SRS and the majority are located in the pancreatic head. Thus, STIR-MRI followed by endoscopic ultrasonography is the most appropriate course. Although calcium provocation-angiography is highly effective in the identification of insulinomas, it is significantly more invasive and should be used only as a last resort. Of particular interest is the observation that in the study of gastrinomas, SRS altered clinical management in almost 50% of patients. This reflected the ability of SRS not only to identify the primary tumor location but clarify equivocal localization results generated by conventional imaging studies. It thus seems that the simplicity, superior sensitivity, high specificity, and cost-effectiveness of SRS mandate that it be the imaging modality in patients with gastrinomas. Because the cost of an SRS is $1800 and may obviate the need for multiple other topographic studies that are at least as expensive, the fiscal dictates further warrant the use of this study as the initial topographic investigation. These observations are probably applicable to all gut NETs, although the likelihood of primary identification in the instance of insulinoma patients may be somewhat less. The timely and cost-effective establishment of the type of NET, its primary site, and the detection metastatic spread will enable determination of the appropriate management strategy.
...
PMID:Approaches to the diagnosis of gut neuroendocrine tumors: the last word (today). 902 13

Chronic injection of an anti-c-KIT receptor tyrosine kinase monoclonal antibody (ACK2) results in the disruption of the normal motility patterns of young BALB/c mice intestine. This effect is accompanied by a drastic decrease in the number of intestinal c-kit-expressing (c-kit+) cells when studied immunohistochemically with the fluorescence-labelled antibody. In order to clarify the mechanism underlying the ACK2 action and the physiological roles of intestinal c-kit+ cells, we studied the excitability of intestinal c-kit+ cells in primary culture by use of the nystatin perforated-patch-clamp technique. Under voltage-clamp at -40 mV, the majority of c-kit+ cells tested (59/70) elicited rhythmic current waves with an amplitude and frequency of 263 +/- 24 pA and 2.30 +/- 0.25 cycles/min (mean +/- SEM), respectively. Intracellular perfusion of the c-kit+ cells with ethylenebis (okonitrilo) tetraacetate (EGTA) as well as a nominally Ca(2+)-free external solution or low holding voltage (< -60 mV) prevented the rhythmic current. The reversal potential of the rhythmic current was close to the equilibrium potential for Cl-(ECl). Moreover the rhythmic current was depressed by a Cl- channel blocker, 4-acetoamido-4-isothiocyanat-ostilbene-2,2'-disulphoni c acid (SITS). The smooth muscle cells freshly dissociated from the same intestinal specimen revealed a Ca(2+)-activated K+ current, as has been described in a variety of smooth muscle cells. Cultured smooth muscle cells from the ileum preparation lacked neither the Ca(2+)-activated K+ nor rhythmic Cl- currents. Smooth muscle cells freshly dissociated from the same ileum preparation and those in culture showed no immunoreactivity with the labelled ACK2, which was consistent with our previous in situ study. Results provided direct evidence that the intestinal c-kit+ cells, but not the smooth muscle cells, possess a rhythmic Cl- current oscillation, suggesting their participation in pacemaker activity for the peristaltic gut movement.
...
PMID:Rhythmic Cl- current and physiological roles of the intestinal c-kit-positive cells. 902 76

To clarify the pathogenesis of total intestinal aganglionosis, an extremely severe from of neural crest-derived cell migration disorder of the gut, the authors studied possible germline mutations of the RET proto-oncogene (10q11.2) in five pedigrees at high risk for congenital aganglionosis. All five patients analyzed were boys, and one had a family history of Hirschsprung's disease. Genomic DNA was extracted from lymphoblastoid cell lines established from patients and their relatives. Polymerase chain reaction (PCR) products, which were amplified using specific primers (RET; exon 1 approximately 20), were electrophoresed to analyze the single-strand conformational polymorphism (SSCP) patterns. DNA sequences were determined in pedigrees showing abnormal SSCP bands. Among the five patients, three germline mutations were found in the receptor tyrosine kinase domain (exon 15; codons 884, 897, and 904). Amino acid substitutions of the Ret protein were predicted based on the mutated nucleotide changes. Phenotypic variations of congenital aganglionosis may depend on the RET mutation pattern and other genetic or environmental determinants. In our series of patients, male sexuality and germline mutation of the RET tyrosine kinase domain were the most likely factors contributing to this form of Hirschsprung's disease.
...
PMID:Germline mutation of the RET proto-oncogene in children with total intestinal aganglionosis. 909 27

Glial cell line-derived neurotrophic factor (GDNF) is a potent survival factor for central dopaminergic neurons, motor neurons and several other populations of neurons in the central and peripheral nervous system. GDNF and its receptor complex of c-RET tyrosine kinase and a glycosyl-phosphatidylinositol linked protein GDNFR-alpha are of great interest due to their potential use in the therapy of Parkinson's and motoneuron diseases. We have cloned the human and rat cDNA sequences of GDNFR-beta, a new gene encoding for a 464 amino acid long homologue of GDNFR-alpha, and assign the locus of this new gene to human chromosome 8p21-22 and mouse chromosome 14D3-E1. Similarly to GDNFR-alpha, GDNFR-beta mediates GDNF-induced Ret autophosphorylation in transfected cells. By northern hybridisation we show that the transcript level of human GDNFR-beta mRNA is high in the adult brain, intestine and placenta and in fetal brain, lung and kidney. Studied by in situ hybridisation, GDNFR-beta mRNA shows in E17 rat embryo different distribution to that of GDNFR-alpha mRNA, especially, in adrenal gland, kidney and gut. In the developing nervous system, GDNFR-beta mRNA expression is restricted to certain neuronal populations, while GDNFR-alpha mRNA is widely expressed also in non-neuronal cells. The distinct tissue distribution of GDNFR-beta mRNA and its ability to mediate GDNF signal in transfected cells suggest a role in signal transduction of GDNF and, possibly, related neurotrophic factors in vivo.
...
PMID:Cloning, mRNA distribution and chromosomal localisation of the gene for glial cell line-derived neurotrophic factor receptor beta, a homologue to GDNFR-alpha. 925 72

Hirschsprung disease (HSCR) is a congenital malformation caused by the absence of ganglion cells in the myenteric and submucosal plexuses of the gut. Recent studies have shown that mutations in the RET, glial-cell-derived neurotrophic factor (GDNF), endothelin-B receptor (EDNRB), endothelin-3 genes are responsible for the occurrence of aganglionosis. Those genes are involved in the development of neural crest derivatives. The RET gene mutation are found in 50% of familial cases and 15% of sporadic cases. The mutations in other genes were found under 10%. In addition to such a low detection rate of the mutations, incomplete penetrance of the mutation was found in all four genes. Those results support multifactorial or polygenic feature of Hirschsprung disease. The additional candidate genes responsible for this disease will be identified along the signaling pathway through RET and EDNRB.
...
PMID:[Molecular basis of Hirschsprung disease]. 946 97

Congenital aganglionic megacolon, commonly known as Hirschsprung disease (HSCR), is the most frequent cause of congenital bowel obstruction. Germline mutations in the RET receptor tyrosine kinase have been shown to cause HSCR. Knockout mice for RET and for its ligand, glial cell line-derived neurotrophic factor (GDNF), exhibit both complete intestinal aganglionosis and renal defects. Recently, GDNF and GFRA1 (GDNF family receptor, also known as GDNFR-alpha), its GPI-linked coreceptor, were demonstrated to be components of a functional ligand for RET. Moreover, GDNF has been implicated in rare cases of HSCR. We have mapped GFRA1 to human chromosome 10q25, isolated human and mouse genomic clones, determined the gene's intron-exon boundaries, isolated a highly polymorphic microsatellite marker adjacent to exon 7, and scanned for GFRA1 mutations in a large panel of HSCR patients. No evidence of linkage was detected in HSCR kindreds, and no sequence variants were found to be in significant excess in patients. These data suggest that GFRA1'S role in enteric neurogenesis in humans remains to be elucidated and that RET signaling in the gut may take place via alternate pathways, such as the recently described GDNF-related molecule neurturin and its GFRA1-like coreceptor, GFRA2.
...
PMID:Human GFRA1: cloning, mapping, genomic structure, and evaluation as a candidate gene for Hirschsprung disease susceptibility. 954 41


<< Previous 1 2 3 4 5 6 7 8 9 10 Next >>

---