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

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Query: EC:2.6.1.44 (AGT)
770 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

1. The frequency (F,s-1) of miniature endplate potentials and the quantal content (m) of endplate potentials were simultaneously measured intracellularly at mouse diaphragm endplates in a bath solution that contained 0.6 mM Ca2+ ions and 5 mM Mg2+ ions. 2. Twin pulses at 4-ms intervals gave the quantal contents of the first (m1) and second (m2) responses. The ratio of m2/m1 was taken as an indicator of the temporal facilitation of the release of transmitter. 3. Lead ions (Pb2+; 10 microM), bis (o-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid (BAPTA; loaded for 60 min at 200 microM), and chlortetracycline (CTC; loaded for 30 min at 80 microM) reduced the values of F and m2/m1. Pb2+ ions and CTC reduced the value of m, whereas BAPTA did not.omega-Agatoxin (omega AGT; 10 ng/ml) reduced the value of m without affecting F or m2/m1. 4. These results suggest that synaptic facilitation is modifiable by agents that can affect systems which buffer intracellular levels of Ca2+ ions.
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PMID:Pharmacologic inhibition of twin-pulse facilitation of release of transmitter quanta at the mouse neuromuscular junction. 901 15

Urolithiasis is uncommon in adolescence and rare in early childhood. In pediatric populations, congenital urinary tract anomalies associated with stasis and infection, idiopathic urolithiasis (adolescents), and nephrocalcinosis (premature infants) account for the majority of urolithiasis patients. Inborn errors of metabolism, such as the primary hyperoxalurias, are rare causes of urolithiasis in childhood. We report six children (mean age at symptom onset 1.3 years; range 0.32-4.1 years) with moderate hyperoxaluria (mean 1.10 +/- 0.58 mmoL/1.73m2 per day; range 0.69-2.19 mmoL/1.73m2 per day). Urolithiasis was present in four. Stones from two children were comprised of calcium oxalate dihydrate. Calcium oxalate crystalluria was seen in two of the patients. Findings included a mean urine calcium concentration of 6.61 +/- 2.28 mg/kg per day, urine citrate of 925.5 +/- 291.29 mg/g of creatinine per day, and mean renal clearance of 99.83 +/- 23.27 mL/min. All children were born full term, none was receiving diuretics, and none had recurrent urinary tract infections. Secondary causes of hyperoxaluria, including dietary oxalate excess, pyridoxine deficiency, and malabsorption, were excluded. Urine glycolate and glycerate were normal in all patients. In one hyperoxaluric member of each sibship, hepatic alanine-glyoxylate aminotransferase and D-glycerate dehydrogenase/glyoxylate reductase activity were normal. The clinical and biochemical features of these children are unlike those in previously recognized hyperoxaluric states. Thus, our description of a separate hyperoxaluric entity, referred to as unclassified hyperoxaluria.
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PMID:Hyperoxaluria and urolithiasis in young children: an atypical presentation. 1060 14

Glyoxylate is an immediate precursor of oxalate, but in its metabolism the conversion into glycine catalyzed by serine:pyruvate/alanine:glyoxylate aminotransferase (SPT/AGT) appears to be the main route. When SPT/AGT is missing as in the case of primary hyperoxaluria type 1 (PH1) more glyoxylate is used for the oxalate production, resulting in calcium oxalate urolithiasis and finally systemic oxalosis. SPT/AGT is a unique enzyme of species-specific dual organelle localization; it is located largely in mitochondria in carnivores and entirely in peroxisomes in herbivores and man. For herbivores, the peroxisomal localization of SPT/AGT is indispensable to avoid massive production of oxalate, probably because liver peroxisomes are the main site of glyoxylate production from glycolate, and plants contain glycolate much more than animal tissues. Recently, we took charge of laboratory examination for 8 cases of primary hyperoxaluria in Japan, and felt that symptoms of some of the Japanese PH1 patients are apparently milder than those of Western patients. The reason of this is not clear, but from the above mentioned seemingly indispensable association of grass-eating with the peroxisomal localization of SPT/AGT it may be related, at least in part, to the food habit of Japanese, especially that of old generation, that they prefer boiled greens rather than frying or raw vegetables.
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PMID:Primary hyperoxaluria type 1 in Japan. 1133 44

Alzheimer's disease (AD) and dementia with vascular component (DVC) are the most prevalent forms of dementia. Both clinical entities share many similarities, but they differ in major phenotypic and genotypic profiles as revealed by structural and functional genomics studies. Comparative phenotypic studies have identified significant differences in 25% of more than 100 parametric variables, including anthropometry, cardiovascular function, aortic atherosclerosis, brain atrophy, blood pressure, blood biochemistry, hematology, thyroid function, folate and vitamin B12 levels, brain hemodynamics and lymphocyte markers. The phenotypic profile of patients with DVC differs from that of AD patients in the following: anthropometric values (weight, height); cardiovascular function (ECG, heart rate); blood pressure; lipid metabolism (HDL-CHO, TGs); uric acid metabolism; peripheral calcium homeostasis; liver function (GOT, GPT, GGT); alkaline phosphatase; lactate dehydrogenase; red and white blood cells; regional brain atrophy (left temporal region, inter-hippocampal distance); and left anterior blood flow velocity. Functional genomics studies incorporating APOE-related changes in biological markers extended the difference between AD and DVC up to 57%. Brain perfusion studies show a severe brain hypoperfusion in dementia associated with enlarged age-dependent arterial perfusion times. Structural genomics studies with AD-related genes, including APP, MAPT, APOE, PS1, PS2, A2M, ACE, AGT, cFOS and PRNP genes, demonstrate different genetic profiles in AD and DVC, with an absolute genetic variation rate ranging from 30% to 80%, depending upon genes and genetic clusters. Single gene analysis identifies relative genetic variations ranging from 0% to 5%. The relative polymorphic variation in genetic clusters integrated by two, three or four genes associated with AD ranges from 1% to 3%. The main phenotypic differences between AD and DVC are genotype-dependent, especially in AD, probably indicating that different genomic factors are determinant for the expression of dementia symptoms which might be accelerated or induced by environmental and/or cerebrovascular factors.
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PMID:Phenotypic profiles and functional genomics in Alzheimer's disease and in dementia with a vascular component. 1526 64

Constitutive genomics are probably determinant for the onset of dementia in conjunction with cerebrovascular and environmental factors. Furthermore, pharmacogenomic studies predict that the therapeutic response in Alzheimer's disease (AD) is genotype-specific, and that the expression of genes involved in the regulation of drug metabolism can influence efficacy and safety issues in pharmacotherapy. AD and dementia with a vascular component (DVC = VD + MXD) are the most prevalent forms of dementia. These clinical entities share many similarities, but they differ in major phenotypic and genotypic profiles, as revealed by structural and functional genomics studies. Comparative phenotypic studies have identified significant differences in 25% of more than 100 parametric variables, including anthropometry, cardiovascular function, aortic atherosclerosis, brain atrophy, blood pressure, blood biochemistry, hematology, thyroid function, folic acid and vitamin B(12) levels, brain hemodynamics and lymphocyte markers. The phenotypic profile of patients with DVC differs from that of AD patients in the following: (a) anthropometric values, (b) cardiovascular function, (c) blood pressure, (d) lipid metabolism, (e) uric acid levels, (f) peripheral calcium levels, (g) liver function (GOT, GPT, GGT), (h) alkaline phosphatase, (i) lactate dehydrogenase, (j) red and white blood cells, (k) regional brain atrophy (left temporal region, inter-hippocampal distance) and (l) brain blood flow velocity. Functional genomics studies incorporating APOE-related changes in biological markers extended the difference between AD and DVC up to 57%. Structural genomics studies with AD-related genes, including APP, MAPT, APOE, PS1, PS2, A2M, ACE, AGT, cFOS and PRNP genes, demonstrate different genetic profiles in AD and DVC, with an absolute genetic variation rate ranging from 30 to 80%, depending upon genes and genetic clusters. Single gene analysis identifies relative genetic variations ranging from 0 to 5%. The relative polymorphic variation in genetic clusters integrated by 2, 3 or 4 genes associated with AD ranges from 1 to 3%. The main phenotypic differences between AD and DVC are genotype-dependent, especially in AD, probably indicating that different genomic factors are essential for the expression of dementia symptoms that might be accelerated or induced by environmental and/or cerebrovascular factors.
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PMID:Genomics and phenotypic profiles in dementia: implications for pharmacological treatment. 1534 38

More than 180 genes distributed across the human genome are potentially involved in the pathogenesis of Alzheimer's disease (AD). The AD population shows a higher genetic variation rate than the control population. Significant differences in allelic distribution and frequency exist when AD-related polygenic clusters are compared with other forms of dementia, indicating that the genetic component in neurodegenerative dementia differs from that of other CNS disorders. The characterization of AD genotype-related phenotypic profiles reveals substantial differences in biological markers among AD clusters associated with different genes and/or allelic combinations. AD and dementia with vascular component (DVC) are the most prevalent forms of dementia. Both clinical entities share many similarities, but they differ in their major phenotypic and genotypic profiles, as revealed by structural and functional genomics studies. Comparative phenotypic studies have identified significant differences in 25% of more than 100 parametric variables, including anthropometric values, cardiovascular function, blood pressure, lipid metabolism, uric acid metabolism, peripheral calcium homeostasis, liver function, alkaline phosphatase, lactate dehydrogenase, red and white blood cells, regional brain atrophy, and brain blood flow velocity. Functional genomic studies incorporating apolipoprotein E (APOE)-related changes in biological markers extended the difference between AD and DVC by up to 57%. Structural genomic studies with AD-related genes, including APP, MAPT, APOE, PS1, PS2, A2M, ACE, AGT, cFOS, and PRNP, demonstrate different genetic profiles in AD and DVC, with an absolute genetic variation rate in the range of 30-80%, depending upon genes and genetic clusters. The relative polymorphic variation in genetic clusters integrated by two, three or four genes associated with AD ranges from 1 to 3%. The main phenotypic differences in AD are genotype dependent, indicating a powerful influence of polygenic factors on the AD phenotypic profile. All these genotypic and phenotypic variations bring about important consequences for the pharmacogenomics of AD.
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PMID:Genomic characterization of Alzheimer's disease and genotype-related phenotypic analysis of biological markers in dementia. 1558 76

DREAM (downstream regulatory element antagonist modulator) is a transcriptional repressor, which binds DREs (downstream response elements) in a Ca2+-regulated manner. The DREs consist of core GTCA motifs, very similar to binding motifs for non-steroid nuclear receptors. In this work, we find that DREAM stimulates basal and ligand-dependent activation of promoters containing vitamin D and retinoic acid response elements (VDREs and RAREs), consisting of direct repeats of the sequence AGT/GTCA spaced by 3 or 5 nt, respectively. Stimulation occurs when the element is located upstream, but not downstream, the transcription initiation site. Activation requires both Ca2+ binding to the EF-hands and the leucine-charged domains (LCDs), analogous to those responsible for the interaction of the nuclear receptors with coregulators. Further more, DREAM can bind both 'in vitro' and in chromatin immunoprecipitation assays to these elements. Importantly, 'in vivo' binding is only observed in vitamin D- or RA-treated cells. These results show that DREAM can function as an activator of transcription on certain promoters and demonstrate a novel role for DREAM acting as a potential modulator of genes containing binding sites for nuclear receptors.
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PMID:The repressor DREAM acts as a transcriptional activator on Vitamin D and retinoic acid response elements. 1584 13

Several proteins associated with mineralised tissue (teeth and bone) or involved in calcium phosphate stabilisation in the body fluids, milk and saliva have been mapped to the q arm of human chromosome 4. These include the dentine/bone proteins dentine sialophosphoprotein (DSPP), dentine matrix protein 1 (DMP1), bone sialoprotein (BSP), matrix extracellular phosphoglycoprotein, osteopontin (OPN), enamelin, ameloblastin, milk caseins, salivary statherin, and proline-rich proteins. The proposed function of those that are multiphosphorylated is: (i) the stabilisation of calcium phosphate in solution (e.g. casein, statherin) preventing spontaneous precipitation and seeded-crystal growth or (ii) promoting biomineralisation (e.g. the phosphophoryn domain of DSPP), where the protein described as a template macromolecule, is proposed to act as a nucleator/promoter of crystal growth. The genes of these proteins have been subjected to conserved chromosomal synteny during mammalian evolution. The multiphosphorylated proteins statherin, caseins, phosphophoryn, BSP and OPN have been characterised as intrinsically disordered. The codon usage patterns for the amino acid serine reveal a bias for AGC and AGT codons within the human genes dspp, dmp1 and bsp, mouse dspp and dmp1 but not significantly for statherin or caseins. This pattern was also observed in the gene encoding hen phosvitin that also contains stretches of multiphosphorylated serines and in the dmp1 gene sequences of mammalian, reptilian and avian classes. In conclusion, these intrinsically disordered multiphosphorylated proteins are the translation products of genes displaying examples of codon usage bias, internal repeats and conserved chromosomal synteny within the mammalian class.
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PMID:A review of protein structure and gene organisation for proteins associated with mineralised tissue and calcium phosphate stabilisation encoded on human chromosome 4. 1589 46

Failure to detoxify the intermediary metabolite glyoxylate in human hepatocytes underlies the metabolic pathology of two potentially lethal hereditary calcium oxalate kidney stone diseases, PH (primary hyperoxaluria) types 1 and 2. In order to define more clearly the roles of enzymes involved in the metabolism of glyoxylate, we have established singly, doubly and triply transformed CHO (Chinese-hamster ovary) cell lines, expressing all combinations of normal human AGT (alanine:glyoxylate aminotransferase; the enzyme deficient in PH1), GR/HPR (glyoxylate/hydroxypyruvate reductase; the enzyme deficient in PH2), and GO (glycolate oxidase). We have embarked on the preliminary metabolic analysis of these transformants by studying the indirect toxicity of glycolate as a simple measure of the net intracellular production of glyoxylate. Our results show that glycolate is toxic only to those cells expressing GO and that this toxicity is diminished when AGT and/or GR/HPR are expressed in addition to GO. This finding indicates that we have been able to reconstruct the glycolate-->glyoxylate, glyoxylate-->glycine, and glyoxylate-->glycolate metabolic pathways, catalysed by GO, AGT, and GR/HPR respectively, in cells that do not normally express them. These results are compatible with the findings in PH1 and PH2, in which AGT and GR/HPR deficiencies lead to increased oxalate synthesis, due to the failure to detoxify its immediate precursor glyoxylate. These CHO cell transformants have a potential use as a cell-based bioassay for screening small molecules that stabilize AGT or GR/HPR and might have use in the treatment of PH1 or PH2.
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PMID:Reconstruction of human hepatocyte glyoxylate metabolic pathways in stably transformed Chinese-hamster ovary cells. 1630 82

Genetic disorders of mineral metabolism cause urolithiasis, renal disease, and osteodystrophy. Most are rare, such that the full spectrum of clinical expression is difficult to appreciate. Diagnosis is further complicated by overlap of clinical features. Dent's disease and primary hyperoxaluria, inherited causes of calcium urolithiasis, are both associated with nephrocalcinosis and urolithiasis in early childhood and renal failure that can occur at any age but is seen more often in adulthood. Bone disease is an inconsistent feature of each. Dent's disease is caused by mutations of the CLCN-5 gene with impaired kidney-specific CLC-5 chloride channel expression in the proximal tubule, thick ascending limb of Henle, and the collecting ducts. Resulting hypercalciuria and proximal tubule dysfunction, including phosphate wasting, are primarily responsible for the clinical manifestations. Low-molecular-weight proteinuria is characteristic. Definitive diagnosis is made by DNA mutation analysis. Primary hyperoxaluria, type I, is due to mutations of the AGXT gene leading to deficient hepatic alanine-glyoxylate aminotransferase activity. Marked overproduction of oxalate by hepatic cells results in the hyperoxaluria responsible for clinical features. Definitive diagnosis is by liver biopsy with measurement of enzyme activity, with DNA mutation analysis used increasingly as mutations and their frequency are defined. These disorders of calcium urolithiasis illustrate the value of molecular medicine for diagnosis and the promise it provides for innovative and more effective future treatments.
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PMID:Stones, bones, and heredity. 1680 Nov 62


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