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:3.6.1.3 (ATPase)
65,361 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The spatial and temporal distribution of the plasma membrane V-ATPase and its encoding mRNA in the midgut of Manduca sexta were investigated during the moult from the fourth to the fifth larval instar. Digoxigenin-labelled RNA probes were used for in situ hybridization of V-ATPase mRNA of both peripheral and integrated subunits; monoclonal antibodies to subunits of the peripheral sector of the purified plasma membrane V-ATPase were used for immunocytochemistry. Extensive mRNA labelling was found in both mature columnar and goblet cells of intermoult and moulting larvae. Hybridization screening in several tissues suggested that only cells with increased V-ATPase biosynthesis were labelled by our hybridization method. Mature goblet cells contain a large amount of V-ATPase in the apical plasma membrane and were therefore expected to contain V-ATPase mRNA. The intense mRNA signal found in mature columnar cells was unexpected. However, after refining the techniques of tissue preparation, immunolabelling in apical blebs of columnar cells was demonstrated. Since this immunoreactivity did not appear to be membrane-associated, it suggested a cytosolic localization of peripheral V1 subunits. The mRNA encoding subunit A of the peripheral V1 sector was distributed unevenly in columnar cells with a strong apical preference, whereas the mRNA for the proteolipid of the integral V0 sector was evenly distributed in the cytosol. This spatial pattern reflected the distribution of free ribosomes and rough endoplasmic reticulum in the cell, supporting the view that V1 subunits are synthesized at free ribosomes, whereas the V0 subunits are synthesized at the rough endoplasmic reticulum. All undifferentiated cells exhibited intense mRNA signals for V-ATPase subunits of both holoenzyme sectors from the start of proliferation and thus precursors of columnar and goblet cells could not be distinguished.
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PMID:Temporal and spatial distribution of V-ATPase and its mRNA in the midgut of moulting Manduca sexta. 878 31

Channel inducing factor (CHIF) is a novel cDNA recently cloned from a rat distal colon cDNA library of dexamethasone-treated animals. While its expression in Xenopus oocytes evokes a potassium channel activity similar to that induced by Isk (minK), its cellular role is not clear. CHIF exhibits significant homologies with proteins that are putatively regulatory (phospholemman, gamma-subunit of Na(+)-K(+)-ATPase, Mat-8) while it differs from the small-conductance potassium channel Isk. We have studied the tissue specificity of CHIF expression in rat by in situ hybridization. CHIF is selectively present in the distal parts of the nephron (medullary and papillary collecting ducts and end portions of cortical collecting tubule) and in the epithelial cells of the distal colon. No expression of CHIF was found in renal proximal tubule, loop of Henle and distal tubule, proximal colon, small intestine, lung, choroid plexus, salivary glands, or brain. To gain some insight into CHIF function, we have investigated, using in situ hybridization and ribonuclease protection assay, whether CHIF mRNA expression could be altered in some situations. In the distal colon, corticosteroid hormones, sodium restriction, low-potassium diet, and metabolic acidosis significantly increased CHIF mRNA expression. In the kidney, metabolic acidosis was the only condition that showed an increase in CHIF mRNA expression. Some of these treatments also altered the expression of the colonic H(+)-K(+)-ATPase mRNA. In summary, CHIF mRNA is selectively expressed in the medullary collecting duct of the kidney and in the epithelium of the distal colon; its expression varies differently in these two target tissues after alterations in corticosteroid status, potassium depletion, and metabolic acidosis. The precise cell-specific functions of CHIF remain to be established.
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PMID:Cellular localization and regulation of CHIF in kidney and colon. 884 4

Changes in contractile and relaxation properties of heart muscle in the cardiac hypertrophy induced by pressure overload have been attributed to alterations in intracellular Ca2+ transport as well as the phenotypic and quantitative changes in contractile protein. However, contradictory data have been reported regarding Ca2+ uptake, release and storage by the sarcoplasmic reticulum (SR). The purpose of this study was to evaluate the changes in SR Ca(2+)-ATPase, ryanodine receptor, calsequestrin and alpha-actin gene expression, and the changes in Ca2+ uptake capacity in various degrees of hypertrophied hearts due to pressure overload. Cardiac hypertrophy was produced in rats by placing a constricting clip (0.80 mm) around the suprarenal abdominal aorta for 8 days. The mRNA levels and Ca2+ uptake capacity were then measured as a function of the severity of cardiac hypertrophy. Ca(2+)-ATPase and ryanodine receptor mRNA levels were increased in mildly hypertrophied hearts but were diminished in severely hypertrophied hearts, showing a bimodal response to pressure overload, Ca2+ uptake capacity showed similar changes along with a positive correlation with Ca(2+)-ATPase mRNA level (r = 0.67, P < 0.001). In contrast, the level of calsequestrin mRNA expression was unaltered and that of alpha-actin was markedly increased over a range of severity of cardiac hypertrophy. These findings suggest that the expression of sarcoplasmic reticulum genes for Ca2+ uptake and release is up- or downregulated dependent on the degree of pressure overload. The gene for the SR Ca2+ storage protein, calsequestrin, might be under different control from these genes in pressure overload. Our findings suggest that the decrease in ratio of mRNAs encoding Ca2+ uptake and release proteins to those encoding contractile proteins could significantly contribute to the slowed contractile and relaxation properties seen in pressure-overloaded hearts.
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PMID:Sarcoplasmic reticulum genes are upregulated in mild cardiac hypertrophy but downregulated in severe cardiac hypertrophy induced by pressure overload. 887 69

In the developing rat cerebrum, the level of different isoforms of Na-K-ATPase mRNA increases significantly during the first three postnatal weeks, which represent the critical period of synaptogenesis and myelination-the two thyroid hormone-sensitive maturational events. To determine the possible functional relationship of these isoforms with maturational events in the developing brain and their mode of regulation by T3, we have examined the effect of hypothyroidism on the expression of the different alpha-isoforms (alpha 1, alpha 2, and alpha 3) of Na-K-ATPase mRNA covering the first 3 wk of postnatal development. Quantitation of these mRNAs from cerebra of 1-, 5-, 10-, 15-, and 20-d-old normal and hypothyroid rats by Northern blot analysis indicate that alpha 3 mRNA is not only predominantly expressed throughout this entire period of study but also represents the species which is most severely affected in the hypothyroid brain. The relative sensitivity for the expression of these mRNAs to T3 were alpha 3 > alpha 1 > alpha 2. These results, together with the report of predominant expression of the alpha 3 isoform in neuronal cells, suggest specific functional involvement of this isoform with the decisive maturational events in the rat brain. Kinetic studies on in vivo induction of Na-K-ATPase alpha-mRNAs by T3 in the 15-d-old hypothyroid rat shows clear stimulation of all the isoforms within 1 h of the administration of the optimal dose (200 micrograms T3/100 g body wt) suggesting a direct, possibly transcriptional effect of the hormone on the expression of these genes.
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PMID:Differential effects of hypothyroidism on Na-K-ATPase mRNA alpha isoforms in the developing rat brain. 890 18

Studies in inner medullary collecting duct (IMCD) cells in primary culture have proposed two mechanisms for Na(+)-independent hydrogen ion transport: an H(+)-adenosinetriphosphatase (H(+)-ATPase) and an H(+)-K(+)-ATPase. In the present study, we have employed two sources of IMCD cells, cells in primary culture derived from the terminal papilla of the Munich-Wistar rat (IMCDp) and an established murine cell line (mIMCD-3), to define the predominant mechanism(s) of Na(+)-independent intracellular pH (pHi) recovery in the IMCD. In confluent monolayers of IMCDp and mIMCD-3 cells, pHi was measured using the pH-sensitive dye 2',7'-bis(carboxyethyl)-5(6)-carboxyfluorescein (BCECF) following addition and withdrawal of NH4Cl. Removal of K+ completely abolished Na(+)-independent pHi recovery in both IMCDp (delta pHi/min = 0.039 +/- 0.006 to 0.005 +/- 0.003; P < 0.001) and in mIMCD-3 (delta pHi/min = 0.055 +/- 0.009 to -0.003 +/- 0.002; P < 0.001) cells, respectively. In mIMCD-3 cells, K(+)-dependent pHi recovery was abolished by either of two specific inhibitors of the H(+)-K(+)-ATPase, Sch-28080 (5 or 10 microM) or A-80915A (10 microM). In contrast, bafilomycin A1 (2.5 and 10 nM), an inhibitor of the H(+)-ATPase, failed to attenuate K(+)-dependent pHi recovery. Moreover, sequence verified mouse gastric and colonic alpha-H(+)-K(+)-ATPase probes hybridized to total RNA from mIMCD-3 cells. Based on these findings, we conclude that Na(+)-independent pHi recovery from an acid load in both IMCDp and mIMCD-3 cells in critically dependent on extracellular K(+)-That K(+)-dependent pHi recovery was inhibited by both Sch-28080 and A-80915A but not by bafilomycin A1 suggests that the predominant mechanism by which Na(+)-independent pHi recovery is accomplished in IMCD is through the H(+)-K(+)-ATPase. Expression of both gastric and colonic alpha-H(+)-K(+)-ATPase mRNA in mIMCD-3 cells suggests that one or both of these H(+)-K(+)-ATPases may be responsible for proton secretion in the IMCD.
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PMID:Role of H(+)-K(+)-ATPase in pHi regulation in inner medullary collecting duct cells in culture. 892 48

The plant plasma membrane H(+)-ATPase energizes the secondary uptake of nutrients and may facilitate cell expansion by acidifying the cell wall. In yeast, Glc stimulates the accumulation of H(+)-ATPase mRNA, and the growth rate supported by various sugars is correlated with H(+)-ATPase protein abundance. Expression of three H(+)-ATPase genes, LHA1, LHA2, and LHA4, was previously detected in tomato (Lycopersicon esculentum). We have characterized the sequence of the LHA4 gene and examined the expression of these three tomato H(+)-ATPase genes in growing tissues and in response to exogenous sugars. LHA4 is a member of the H(+)-ATPase subfamily, including the Arabidopsis thaliana genes AHA1, AHA2, and AHA3. The 5' untranslated region of the deduced LHA4 cDNA contains a short, open reading frame very similar to that in the Nicotiana plumbaginifolia gene PMA1. LHA4 transcript abundance in seedlings is correlated with cell growth, being 2.5 times greater in hypocotyls of dark- versus light-grown plants. The accumulation of both LHA4 and LHA2 mRNAs is induced by the addition of exogenous sugars and this induction appears to be dependent on sugar uptake and metabolism, because mannitol and 3-O-methylglucose do not stimulate mRNA accumulation. These results suggest that the induction of expression of H(+)-ATPase genes by metabolizable sugars may be part of a generalized cellular response to increased cell growth and metabolism promoted by the availability of an abundant carbon source.
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PMID:Sugar regulates mRNA abundance of H(+)-ATPase gene family members in tomato. 893 20

We have previously reported that the Wistar/Furth (W/Fu) rat strain is resistant to mineralocorticoid hypertension. In the current study, we have examined renal mRNA levels for mineralocorticoid receptor (MR), glucocorticoid receptor (GR), renin and Na+, K(+)-ATPase in response to treatment with mineralocorticoids. Uninephrectomized male Wistar (WI) and W/Fu rats were treated with aldosterone or deoxycorticosterone acetate (DOCA) and were given 1% NaCl to drink. Rats were sacrificed after 1, 3 or 7 days of treatment. Renal MR and ATPase mRNA levels were significantly reduced in aldosterone and DOCA-treated WI rats (e.g. MR was 30% on day 3 and ATPase was 50% of control on day 7 of aldosterone treatment). Unexpectedly, GR mRNA levels paralleled the changes in MR. In W/Fu rats the level of message was either unchanged or only moderately altered by this treatment. In vivo administration of the MR antagonist RU28318 or the GR antagonist RU38486 to WI rats for 4 days reduced renal mRNA levels for both subunits of ATPase. In the W/Fu rat, this treatment resulted in no change in the alpha subunit and an increase in the beta subunit of ATPase. In preliminary studies, we have determined that the W/Fu rat is also resistant to dexamethasone-induced hypertension. These studies suggest that altered MR- and GR-mediated mechanisms may contribute to the resistance of the W/Fu rat strain to steroid-induced hypertension.
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PMID:The resistance of the Wistar/Furth rat strain to steroid hypertension. 896 28

The plasma membrane H(+)-ATPase gene was cloned and sequenced from the extremely acidophilic green alga Dunaliella acidophila and from the extremely halotolerant Dunaliella salina. A special feature of the Dunaliella H(+)-ATPase is an extended C-terminal domain. The deduced amino acid sequences of the two proteins are 75% identical but differ in their C terminus. A hydrophilic loop within this domain in D. salina, which presumably faces the cell exterior, has a high ratio of acidic over basic amino acids, typical of halophilic proteins. The amount of the ATPase protein in plasma membranes and the level of its mRNA transcript in D. acidophila are far higher than in D. salina, suggesting that D. acidophila overexpresses the enzyme. A pH shift from 9.0 to 7.0 induces in D. salina a large increase in the level of the H(+)-ATPase mRNA and in the amount of the H(+)-ATPase protein. This suggests that the expression of the H(+)-ATPase in D. salina is pH-regulated at the transcriptional level. The implications of these findings are discussed with respect to the adaptive pressures imposed on these algal species by their exceptional environmental conditions.
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PMID:Primary structure and effect of pH on the expression of the plasma membrane H(+)-ATPase from Dunaliella acidophila and Dunaliella salina. 897 5

The decreased expression of the sarcoplasmic reticulum Ca(2+)-ATPase associated with cardiac hypertrophy was investigated in cultured neonatal rat cardiac myocytes. Northern blot analysis indicated a significant 55-60% decrease in Ca(2+)-ATPase mRNA levels and after 12 and 24 h of treatment with the phorbol ester phorbol myristate acetate (PMA). Myocytes treated with the phorbol ester for 80 h showed a significant 34% decrease (relative to vehicle-treated control cells) in the levels of Ca(2+)-ATPase protein, and a significant 38% increase in the levels of alpha-sarcomeric actin, as assessed by Western blot analysis using specific antibodies. Immunocytochemistry of myocytes treated for 72 h with the phorbol ester revealed a hypertrophied cell morphology, and showed a marked decrease in Ca(2+)-ATPase staining intensity. Contractile calcium transients were evaluated through the use of indo-1. It was found that the t1/2 for the decline of calcium transient was significantly prolonged by PMA treatment (0.51 +/- 0.15) when compared to controls (0.38 +/- 0.17, P < 0.001). Treatment of myocytes with endothelin-1 also led to a 35% decrease in sarcoplasmic reticulum Ca(2+)-ATPase mRNA levels. It is concluded that phorbol ester treatment of neonatal rat cardiac myocytes induces similar changes in Ca(2+)-ATPase mRNA levels. It is concluded that phorbol ester treatment of neonatal rat cardiac myocytes induces similar changes in Ca(2+)-ATPase gene expression as observed in vivo in the hypertrophied and failing heart. The observed prolongation in t1/2 for [Ca2+]i decline might be due to the observed depressed levels for sarcoplasmic reticulum Ca(2+)-ATPase in PMA treated cells.
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PMID:Phorbol myristate acetate-induced hypertrophy of neonatal rat cardiac myocytes is associated with decreased sarcoplasmic reticulum Ca2+ ATPase (SERCA2) gene expression and calcium reuptake. 900 63

Although the kidney plays the major role in the regulation of systemic K+ homeostasis, the colon also participates substantively in K+ balance. The colon is capable of both K+ absorption and secretion, the magnitude of which can be modulated in response to dietary K+ intake. The H(+)-K(+)-adenosinetriphosphatase (H(+)-K(+)-ATPase) has been proposed as a possible mediator of K+ absorption in distal colon, but inhibitor profiles obtained in recent studies suggest that two, and perhaps more, distinct H(+)-K(+)-ATPase activities may be present in mammalian distal colon. We have developed highly specific probes for the catalytic alpha-subunits of colonic and gastric H(+)-K(+)-ATPase, alpha 1-Na(+)-K(+)-ATPase, and beta-actin, which were used in Northern analysis of total RNA from whole distal colon and stomach obtained from one of three experimental groups of rats: 1) controls, 2) chronic dietary K+ depletion, and 3) chronic metabolic acidosis. The probe for the colonic but not the gastric H(+)-K(+)-ATPase alpha-isoform hybridized to distal colon total RNA in all groups. A significant increase in colonic H(+)-K(+)-ATPase mRNA abundance was observed in response to chronic dietary K+ depletion but not to chronic metabolic acidosis. The alpha 1-isoform of Na(+)-K(+)-ATPase, which is also expressed in distal colon, did not respond consistently to either chronic dietary K+ depletion or chronic metabolic acidosis. The gastric probe did not hybridize to total RNA from distal colon but, as expected, hybridized to total stomach RNA. However, the abundance of gastric H(+)-K(+)-ATPase or Na(+)-K(+)-ATPase in stomach was not altered consistently by either chronic dietary K+ depletion or metabolic acidosis. Under the conditions of this study, it appears that the mRNA encoding the colonic alpha-isoform is upregulated by chronic dietary K+ restriction, a condition shown previously to increase K+ absorption in the distal colon.
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PMID:Effect of chronic hypokalemia on H(+)-K(+)-ATPase expression in rat colon. 903 45


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