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)

Immobilization causes a transient increase in bone resorption and a prolonged depression of bone formation. We have studied the effect of immobilization on the expression of two proteins believed to have a major functional role in osteoclasts, the proteolipid subunit of vacuolar H(+)-ATPase (VPL) and carbonic anhydrase II (CA II). Trabecular bone from immobilized rat tibiae was analyzed using northern and slot blotting, polymerase chain reaction (PCR), and morphometric analysis. CA II and VPL transcription was rapidly stimulated in trabecular bone of immobilized rat tibiae. Osteoclast number increased and the trabecular bone volume decreased during immobilization. Fluorescein-labeled cDNA probes and a confocal laser scanning microscope were used to study the localization of VPL and CA II mRNAs in situ in osteoclasts and other bone-derived cells attached to bovine bone slices in vitro. CA II and VPL mRNA were highly expressed in actively resorbing osteoclasts, but in nonresorbing osteoclasts mRNA expression was very low or not detectable at all. These results strongly suggest that both CA II and VPL have an important functional role in bone resorption. Finally, in the bone cell population isolated for these studies, CA II was found to be highly specific for osteoclasts whereas VPL was also detected in other cell types.
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PMID:Proton channel part of vacuolar H(+)-ATPase and carbonic anhydrase II expression is stimulated in resorbing osteoclasts. 842 45

The activity of gastric parietal cells in terms of hydrochloric acid (HCl) secretion is regulated by the interaction of stimulatory substances (e.g. gastrin) and inhibitors (e.g. somatostatin) acting in an endocrine and paracrine mode, as well as luminal factors. In the present study the following parameters were measured: the synthesis (mRNA), storage (tissue peptide concentration) and secretion (plasma peptide concentration) of somatostatin and gastrin following short-term treatment of rats with pentagastrin (acid stimulant), secretin, omeprazole (reduces gastric acidity by inactivating gastric H/K ATPase) and the somatostatin analogue octreotide (reduces gastric acidity by inhibiting both the parietal cell and gastrin). The mRNA coding for H/K ATPase and carbonic anhydrase II (CA II), the two enzymes responsible for the generation of hydrogen ions from the parietal cell, were also quantitated. In response to octreotide, somatostatin peptide and mRNA levels in the fundus rose to 180 +/- 16% (P < 0.001) and 1073 +/- 356% (P < 0.05) of control, respectively. In contrast, octreotide caused a decrease in antral somatostatin peptide and its mRNA did not change significantly. No significant changes in synthesis, secretion or storage of gastrin were observed except for omeprazole induced hypergastrinaemia (580 +/- 76%, P < 0.001). H/K ATPase and CA II mRNA were largely unaffected except for an increase in CA II mRNA following octreotide and a decrease in H/K ATPase mRNA after pentagastrin. These data support the concept of the differential control of antral and fundic somatostatin synthesis and provide evidence for a regulatory loop by which somatostatin can influence its own synthesis.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Secretory and biosynthetic responses of gastrin and somatostatin to acute changes in gastric acidity. 852 6

Protein sorting in eukaryotic cells is mainly done by specific targeting of polypeptides. The present evidence from oocytes, neurons, and some other polarized cells suggests that protein sorting can be further facilitated by concentrating mRNAs to their corresponding subcellular areas. However, very little is known about the mechanism(s) involved in mRNA targeting, or how widespread and dynamic such mRNA sorting might be. In this study, we have used an in vitro cell culture system, where large multinucleated osteoclasts undergo continuous structural and functional changes from polarized (resorbing) to a nonpolarized (resting) stage. We demonstrate here, using a nonradioactive in situ hybridization technique and confocal microscopy, that mRNAs for several vacuolar H(+)-ATPase subunits change their localization and polarity in osteoclasts according to the resorption cycle, whereas mRNA for cytoplasmic carbonic anhydrase II is found diffusely located throughout the osteoclast during the whole resorption cycle. Antisense RNA against the 16-kDa or 60-kDa V-ATPase subunit inhibits polarization of the osteoclasts, as determined by cytoskeleton staining. Antisense RNA against carbonic anhydrase II, however, has no such effect.
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PMID:Resorption-cycle-dependent polarization of mRNAs for different subunits of V-ATPase in bone-resorbing osteoclasts. 874 45

Structurally and functionally distinct populations of intercalated cells have been described in the collecting duct of both rat and rabbit. However, little is known about these cells in the mouse kidney. The study presented here examines ultrastructural and immunological characteristics of different types of intercalated cells in the mouse. Kidneys of two strains of normal female mice, C57BL/6 and IBR, were preserved by in vivo perfusion with 1% glutaraldehyde or paraformaldehyde-picric acid fixatives and processed for morphological evaluation or light and electron microscopic immunohistochemistry, respectively. The avidin-biotin-horseradish peroxidase procedure was performed on was sections using antibodies against carbonic anhydrase II, H+ -ATPase and Band 3 protein. Immunogold cytochemistry was performed on Lowicryl sections using antibodies to H+ -ATPase and Band 3 protein. Colocalization of H+ -ATPase and Band 3 protein was performed by double labeling using an immunogold technique with silver enhancement. Intercalated cells identified by positive staining for H+ -ATPase and carbonic anhydrase II constituted 35% to 40% of all cells in the connecting tubule (CNT), cortical collecting duct (CCD), and outer medullary collecting duct (OMCD). Type A intercalated cells identified by positive Band 3 staining constituted 16%, 24%, and 33% of the total cell population in the CNT, CCD, and OMCD, respectively. Electron microscopy and immunogold cytochemistry demonstrated three distinct populations of intercalated cells. Type A intercalated cells with apical H+ -ATPase and basolateral Band 3 immunoreactivity were present in all segments examined, and had prominent apical microprojections and characteristic tubulovesicular structures beneath the apical surface, both coated with studs on the cytoplasmic face. Type B intercalated cells with basolateral and cytoplasmic H+-ATPase and no Band 3 immunoreactivity were most frequently observed in the initial collecting tubule, but were present also in the CNT and early CCD. Type B intercalated cells had a fairly smooth apical surface, a gray zone free of organelles beneath the apical plasma membrane, and small cytoplasmic vesicles without studs throughout the cell. A third type of intercalated cell with apical and cytoplasmic H+-ATPase, but no basolateral Band 3 protein, was observed exclusively in the CNT and the initial collecting tubule. This type of cell was large, with numerous mitochondria, and vesicles coated with studs were present throughout the cell. It resembled a third type of intercalated cell described previously in the rat. It is concluded that three morphologically and immunologically distinct types of intercalated cells are present in the mouse kidney.
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PMID:Identification of distinct subpopulations of intercalated cells in the mouse collecting duct. 878 96

The saccular membranes of trout (Oncorhynchus mykiss) and turbot (Scophthalmus maximus) were examined to characterize specialized epithelial cells that might be responsible for ion exchange. The approach for localizing cell types was new for this tissue, as observations were made with a stereomicroscope and a light microscope in order to have a general view of the epithelium. No important differences between the two species were seen. The saccular tissue is a monolayer epithelium (except for the macula neural zone) surrounded by a layer of connective tissue invaded by many blood vessels. The use of the fluorescent probe DAPSMI and zinc iodide/osmium fixation-coloration defined two areas in which ionocytes were present. In the first, large ionocytes were grouped into a nearly complete, crowned meshwork around, but separated from, the macula. In the second area, opposite the macula, the ionocytes were smaller, cubical, and grouped in patches. Cells rich in Na+, K+-ATPase and carbonic anhydrase II were present in both areas. Contrary to previous studies in mammals and fish, ionocytes were also found in the epithelium of the saccule.
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PMID:Distribution of ionocytes in the saccular epithelium of the inner ear of two teleosts (Oncorhynchus mykiss and Scophthalmus maximus). 918

Osteopetrosis in laboratory animals is a metabolic bone disease characterized by increased skeletal mass. It is inherited as an autosomal recessive and results from a defect in the development and/or function of osteoclasts. We studied two enzymes essential for bone resorption, carbonic anhydrase II isoenzyme (CA II) and H+ -ATPase, in osteoclasts from four osteopetrotic mutations in the rat; namely incisors-absent (ia), osteopetrosis (op), toothless (tl), and microphthalmia (mib), to test the hypothesis that reduced bone resorption in one or more of these mutations results from defects in the synthesis or activity of one of these enzymes. CA II was present in most osteoclasts from normal, tl, op, and mib littermates and was homogeneously distributed in cytoplasm. CA II staining in ia osteoclasts was more variable and less intense than in the other mutations. H+-ATPase was also present in osteoclasts from normal animals and mutants and immunostaining showed clear polarization to the ruffled border region in all normal rats and mutants except ia, which showed diffuse distribution of staining in the cytoplasm. H+-ATPase activity (proton transport) in a related tissue, kidney, was normal in tl and ia rats but increased in op and mib rats compared to their normal littermates. These results suggest that the osteoclasts in osteopetrotic rat mutations are not abnormal with respect to the distribution of CA II and H+ -ATPase and that the function of these enzymes in the skeleton, while likely normal, needs to be tested directly in bone.
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PMID:Carbonic anhydrase II and H+ -ATPase in osteoclasts of four osteopetrotic mutations in the rat. 993 Aug 84

A low-bicarbonate concentration and an acidic pH in the luminal fluid of the epididymis and vas deferens are important for sperm maturation. These factors help maintain mature sperm in an immotile but viable state during storage in the cauda epididymidis and vas deferens. Two proton extrusion mechanisms, an Na(+)/H(+) exchanger and an H(+)ATPase, have been proposed to be involved in this luminal acidification process. The Na(+)/H(+) exchanger has not yet been localized in situ, but we have reported that H(+)ATPase is expressed on the apical membrane of apical (or narrow) and clear cells of the epididymis. These cells are enriched in carbonic anhydrase II, indicating the involvement of bicarbonate in the acidification process and suggesting that the epididymis is a site of bicarbonate reabsorption. Previous unsuccessful attempts to localize the Cl/HCO(3) anion exchanger AE1 in rat epididymis did not investigate other anion exchanger (AE) isoforms. In this report, we used a recently described SDS antigen unmasking treatment to localize the Cl/HCO(3) exchanger AE2 in rat and mouse epididymis. AE2 is highly expressed in the initial segment, intermediate zone, and caput epididymidis, where it is located on the basolateral membrane of epithelial cells. The cauda epididymidis and vas deferens also contain basolateral AE2, but in lower amounts. The identity of the AE2 protein was further confirmed by the observation that basolateral AE2 expression was unaltered in the epididymis of AE1-knockout mice. Basolateral AE2 may participate in bicarbonate reabsorption and luminal acidification, and/or may be involved in intracellular pH homeostasis of epithelial cells of the male reproductive tract.
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PMID:Immunolocalization of AE2 anion exchanger in rat and mouse epididymis. 1049 32

The role of proton transport and production in osteoclast differentiation was studied in vitro by inhibiting the transcription/translation of carbonic anhydrase II (CA II) and vacuolar H(+)-ATPase (V-ATPase) by antisense RNA molecules. Antisense RNAs targeted against CA II, or the 16 kDa or 60 kDa subunit of V-ATPase were used to block the expression of the specific proteins. A significant decrease in bone resorption rate and TRAP-positive osteoclast number was seen in rat bone marrow cultures and fetal mouse metacarpal cultures after antisense treatment. Intravacuolar acidification in rat bone marrow cells was also significantly decreased after antisense treatment. The CA II antisense RNA increased the number of TRAP-positive mononuclear cells, suggesting inhibition of osteoclast precursor fusion. Antisense molecules decreased the number of monocytes and macrophages, but increased the number of granulocytes in marrow cultures. GM-CSF, IL-3 and IL-6 were used to stimulate haematopoietic stem cell differentiation. The 16 kDa V-ATPase antisense RNA abolished the stimulatory effect of GM-CSF, IL-3 and IL-6 on TRAP-positive osteoclast formation, but did not affect the formation of monocytes and macrophages after IL-3 treatment, or the formation of granulocytes after IL-6 treatment. These results suggest that CA II and V-ATPase are needed, not only for the actual resorption, but also for osteoclast formation in vitro.
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PMID:Inhibition of intravacuolar acidification by antisense RNA decreases osteoclast differentiation and bone resorption in vitro. 1052 2

Acidification of the epididymal lumen has been suggested to play an important role in sperm functions; however, the cell types, pumps, and mechanisms involved have not been fully addressed. In this study, carbonic anhydrase II (CA II) and a 67-kd subunit of Neurospora crassa vacuolar proton adenosinetriphosphatase (H+ V-ATPase) pump were immunolocalized using light microscopy and electron microscopy (EM) in the epididymis of rats and mice. In both animals, narrow cells, identified in the initial segment and intermediate zone of the epididymis, contained numerous small vesicles in their apical region, often cup-shaped in appearance. In the mouse but not rat, these cells also possessed numerous cisternae of smooth endoplasmic reticulum, suggesting steroid synthesis; and cytoplasmic blebs of their apical cell surface, which appeared to detach, suggesting apocrine secretion. Anti-CA II antibody was immunocytochemically localized in the light microscope within narrow cells but not over any other cell types of the entire epididymis. Anti-H+ V-ATPase antibody was also localized in narrow cells of the initial segment and intermediate zone; as well as clear cells of the caput, corpus, and cauda regions. Using EM, gold particles for anti-CA II and H+ V-ATPase antibodies were noted in the apical region of narrow cells in relation to the numerous, small, cup-shaped vesicles. Although CA II was mainly located in the cytosol near these vesicles, H+ V-ATPase appeared on their delimiting membrane and on the apical plasma membrane of these cells. A similar distribution was noted for H+ V-ATPase in clear cells. The nature of the small vesicles of the apical region of narrow cells was examined with electron-dense fluid phase tracers that were introduced into the epididymal lumen. The tracers appeared within these vesicles and a few endosomes 1 hour after injection, suggesting that they contact the apical plasma membrane. Since these vesicles are also related to CA II and H+ V-ATPase, the data suggests that, as the site of proton production, the vesicles recycle to and from the apical cell surface, and in this way, deliver protons to the epididymal lumen for acidification. Clear cells and their expression of H+ V-ATPase may also serve in this function. In summary, both narrow and clear cells appear to be involved in luminal acidification, an activity that may be essential for sperm as they traverse and are stored in the epididymis.
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PMID:Immunolocalization of CA II and H+ V-ATPase in epithelial cells of the mouse and rat epididymis. 1081 45

The Na,K-ATPase, which catalyzes the active transport of Na(+) and K(+), has two principal subunits (alpha and beta) that have several genetically distinct isoforms. Most of these isoforms are expressed in the nervous system, but certain ones are preferentially expressed in glia and others in neurons. Of the beta isoforms, beta1 predominates in neurons and beta2 in astrocytes, although there are some exceptions. Here we demonstrate that beta3 is expressed in rat and mouse white matter oligodendrocytes. Immunofluorescence microscopy identified beta3 in oligodendrocytes of rat brain white matter in typical linear arrays of cell bodies between fascicles of axons. The intensity of stain peaked at 20 postnatal days. beta3 was identified in cortical oligodendrocytes grown in culture, where it was expressed in processes and colocalized with antibody to galactocerebroside. In the mouse and rat optic nerve, beta3 stain was seen in oligodendrocytes, where it colocalized with carbonic anhydrase II. For comparison, optic nerve was stained for the beta1 and beta2 subunits, showing distinct patterns of labelling of axons (beta1) and astrocytes (beta2). The C6 glioma cell line was also found to express the beta3 isoform preferentially. Since beta3 was not found at detectable levels in astrocytes, this suggests that C6 is closer to oligodendrocytes than astrocytes in the glial cell lineage.
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PMID:Oligodendrocytes in brain and optic nerve express the beta3 subunit isoform of Na,K-ATPase. 1094 Nov 47


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