H+/Ca2+ exchange in rabbit renal cortical endosomes

Hilden, Shirley A.; Madias, Nicolaos E.

doi:10.1007/bf01871274

Cited by 18 publications

(11 citation statements)

References 26 publications

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“…Stimulation of 45Ca 2+ uptake by the vesicles was possible, as ATP did stimulate this uptake in the present studies and in previous observations from our laboratory (Fig. 4 ofHilden & Madias, 1989). Like the response in endosomes, PCMB had no effect on 45Ca2+ uptake by BBMV (Fig.…”

Section: T)contrasting

confidence: 34%

“…The mechanisms mediating the regulation of vacuolar pH are under active investigation. In recent studies, we have described the presence of a C1 conductance (Hilden, Johns & Madias, 1988), an H+/Ca 2+ exchanger (Hilden & Madias, 1989) and a Na+/H + exchanger (Hilden, Ghoshroy & Madias, 1990) in an H + ATPase-bearing endosomal fraction isolated from rabbit renal cortex. We have suggested that these secondary transporters might represent important modulators of the vacuolar H + ATPase activity.…”

Section: Introductionmentioning

confidence: 98%

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Effect of sulfhydryl compounds on ATP-stimulated H+ transport and Cl− uptake in rabbit renal cortical endosomes

Hilden

Madias

1991

J. Membrain Biol.

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The vacuolar H+ ATPase is inhibited by N-ethylmaleimide (NEM), a sulfhydryl compound, suggesting the involvement of a sulfhydryl group in this transport process. We have examined the effects of several sulfhydryl-containing compounds on the vacuolar H+. ATPase of rabbit renal cortical endosomes. A number of such compounds were effective inhibitors of endosomal H+ transport at 10(-5)-10(-6) M, including NEM, mersalyl, aldrithiol, 5,5' dithiobis (2-nitrobenzoic acid), p-chloromercuribenzoic acid (PCMB) and p-chloromercuriphenyl sulfonic acid (PCMBS). NEM, mersalyl, aldrithiol and PCMBS had no effect on pH-gradient dissipation, whereas PCMB decreased the pH gradient faster than control. In the absence of ATP, PCMB (10(-4) M) stimulated endosomal 36Cl- uptake, particularly in the presence of an inside-alkaline pH gradient (pHin = 7.6/pHout = 5.5). This result was not an effect of PCMB on the Cl(-)-conductive pathway. The less permeable PCMBS did not stimulate 36Cl- uptake. The effects of PCMB were concentration dependent and were prevented by dithioerithritol. ATP-dependent 36Cl- uptake was decreased by addition of PCMB. Finally, PCMB had no effect on 45Ca2+ uptake. These results support the presence of two functionally important sulfhydryl groups in this endosomal preparation. One such group is involved with ATP-driven H+ transport and must be located on the cytoplasmic surface of the endosomal membrane. The second sulfhydryl group must reside on the internal surface of the endosomal membrane and relates to a PCMB-activated Cl-/OH- exchanger that is functional both in the presence and absence of ATP. This endosomal transporter is similar to the PCMB-activated Cl-/OH- exchanger recently described in rabbit renal brush-border membranes.

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Section: T)contrasting

confidence: 34%

Section: Introductionmentioning

confidence: 98%

Effect of sulfhydryl compounds on ATP-stimulated H+ transport and Cl− uptake in rabbit renal cortical endosomes

Hilden

Madias

1991

J. Membrain Biol.

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“…Indeed, after 20 min of endocytosis by cultured fibroblasts in an incubation medium containing 2 mM Ca 2ϩ , the endosomal free Ca 2ϩ concentration was estimated at ‫3ف‬ M (Gerasimenko et al, 1998). There is also evidence that lysosomes contain a mobilizable pool of Ca 2ϩ (Haller et al, 1996), and that both endosomal (Hilden and Madias, 1989) and lysosomal (Lemons and Thoene, 1991) membranes contain Ca 2ϩ transport systems. Furthermore, a rise in cytosolic Ca 2ϩ has been shown to be necessary for lysosome-lysosome fusion (Bakker et al, 1997), lysosome-phagosome fusion (Jaconi et al, 1990), and lysosome-plasma membrane fusion (Rodriguez et al, 1997).…”

Section: Discussionmentioning

confidence: 99%

The Role of Intraorganellar Ca2+In Late Endosome–Lysosome Heterotypic Fusion and in the Reformation of Lysosomes from Hybrid Organelles

Pryor

Mullock

Bright

et al. 2000

The Journal of Cell Biology

322

354

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We have investigated the requirement for Ca2+ in the fusion and content mixing of rat hepatocyte late endosomes and lysosomes in a cell-free system. Fusion to form hybrid organelles was inhibited by 1,2-bis(2-aminophenoxy) ethane-N,N,N′,N′-tetraacetic acid (BAPTA), but not by EGTA, and this inhibition was reversed by adding additional Ca2+. Fusion was also inhibited by methyl ester of EGTA (EGTA-AM), a membrane permeable, hydrolyzable ester of EGTA, and pretreatment of organelles with EGTA-AM showed that the chelation of lumenal Ca2+ reduced the amount of fusion. The requirement for Ca2+ for fusion was a later event than the requirement for a rab protein since the system became resistant to inhibition by GDP dissociation inhibitor at earlier times than it became resistant to BAPTA. We have developed a cell-free assay to study the reformation of lysosomes from late endosome–lysosome hybrid organelles that were isolated from the rat liver. The recovery of electron dense lysosomes was shown to require ATP and was inhibited by bafilomycin and EGTA-AM. The data support a model in which endocytosed Ca2+ plays a role in the fusion of late endosomes and lysosomes, the reformation of lysosomes, and the dynamic equilibrium of organelles in the late endocytic pathway.

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“…Pryor et al (41) recently proposed that endocytosed Ca 2ϩ released from the lumen of endocytic organelles (such as late endosomes and lysosomes) may be used to mediate membrane fusion events at several stages of the endocytic pathway. There is also evidence demonstrating that lysosomes contain a mobilizable pool of Ca 2ϩ (44) and that endosomal (45) and lysosomal (46) membranes contain Ca 2ϩ transport systems. Furthermore, Malik et al (24) recently showed that Ca 2ϩ ionophore stimulation of M. tuberculosisinfected human macrophages leads to the demise of the intracellular mycobacteria coincidental with the progression of the bacteria to an intracellular compartment that was lysosomal and acidified.…”

Section: Discussionmentioning

confidence: 99%

ATP-Mediated Killing ofMycobacterium bovisBacille Calmette-Guérin Within Human Macrophages Is Calcium Dependent and Associated with the Acidification of Mycobacteria-Containing Phagosomes

Stober

Lammas

et al. 2001

The Journal of Immunology

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We previously demonstrated that extracellular ATP stimulated macrophage death and mycobacterial killing within Mycobacterium bovis Bacille Calmette-Guérin (BCG)-infected human macrophages. ATP increases the cytosolic Ca2+ concentration in macrophages by mobilizing intracellular Ca2+ via G protein-coupled P2Y receptors, or promoting the influx of extracellular Ca2+ via P2X purinoceptors. The relative contribution of these receptors and Ca2+ sources to ATP-stimulated macrophage death and mycobacterial killing was investigated. We demonstrate that 1) ATP mobilizes Ca2+ in UTP-desensitized macrophages (in Ca2+-free medium) and 2) UTP but not ATP fails to deplete the intracellular Ca2+ store, suggesting that the pharmacological properties of ATP and UTP differ, and that a Ca2+-mobilizing P2Y purinoceptor in addition to the P2Y2 subtype is expressed on human macrophages. ATP and the Ca2+ ionophore, ionomycin, promoted macrophage death and BCG killing, but ionomycin-mediated macrophage death was inhibited whereas BCG killing was largely retained in Ca2+-free medium. Pretreatment of cells with thapsigargin (which depletes inositol (1,4,5)-trisphosphate-mobilizable intracellular stores) or 1,2-bis-(2-aminophenoxy)ethane-N, N, N′,N′-tetraacetic acid acetoxymethyl ester (an intracellular Ca2+ chelator) failed to inhibit ATP-stimulated macrophage death but blocked mycobacterial killing. Using the acidotropic molecular probe, 3-(2,4-dinitroanilino)-3′-amino-N-methyl dipropylamine, it was revealed that ATP stimulation promoted the acidification of BCG-containing phagosomes within human macrophages, and this effect was similarly dependent upon Ca2+ mobilization from intracellular stores. We conclude that the cytotoxic and bactericidal effects of ATP can be uncoupled and that BCG killing is not the inevitable consequence of death of the host macrophage.

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H+/Ca2+ exchange in rabbit renal cortical endosomes

Cited by 18 publications

References 26 publications

Effect of sulfhydryl compounds on ATP-stimulated H+ transport and Cl− uptake in rabbit renal cortical endosomes

Effect of sulfhydryl compounds on ATP-stimulated H+ transport and Cl− uptake in rabbit renal cortical endosomes

The Role of Intraorganellar Ca2+In Late Endosome–Lysosome Heterotypic Fusion and in the Reformation of Lysosomes from Hybrid Organelles

ATP-Mediated Killing ofMycobacterium bovisBacille Calmette-Guérin Within Human Macrophages Is Calcium Dependent and Associated with the Acidification of Mycobacteria-Containing Phagosomes

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