Regulation of ATP-Dependent Endosome Acidification

Fuchs, Renate; Schmid, Sandra L.; Mellman, Ira; Klapper, Herbert

doi:10.1007/978-3-642-84295-5_17

Cited by 5 publications

(4 citation statements)

References 19 publications

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“…Endosome acidification is generated by means of an ATP-driven proton pump (Galloway et al, 1983;Merion et al, 1983). This ATP-dependent acidification is electrogenic and is modulated in early endosomes by the presence of the Na', K+-ATPase which reduces the degree of acidification relative to late endosomes and lysosomes (Fuchs et al, 1989;Cain et al, 1989). Differences in extent of acidification of various endosome populations appears to correlate well with differences in function.…”

Section: Acid Sortingmentioning

confidence: 97%

“…Receptors and ligands on the pathway of endocytosis encounter regions of increasing acidity (Murphy et al, 1984;Kielian et al, 1986;Yamashiro and Maxfield, 1987;Schmid et al, 1989). Endosome acidification is generated by means of an ATP-driven proton pump (Galloway et al, 1983;Merion et al, 1983).…”

Section: Acid Sortingmentioning

confidence: 99%

“…Localisation of rub5 and rub7 to specific endosomal populations (Chavrier et al, 1990) combined with the development of procedures, notably free-flow electrophoresis, for the preparation of highly purified endosome populations should allow this question to be addressed. Results to date suggest that it is possible to purify functional endosomal compartments: in vitro, endosomes retain the ability to be acidified (Schmid et al, 1988(Schmid et al, , 1989. Using these purified organelles in cell-free assays which have already been developed should allow detailed analysis of all the compartments on the route to lysosomes.…”

Section: Lysosomesmentioning

confidence: 99%

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The mechanism of receptor‐mediated endocytosis

Smythe

Warren

1991

European Journal of Biochemistry

153

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Section: Acid Sortingmentioning

confidence: 97%

Section: Acid Sortingmentioning

confidence: 99%

Section: Lysosomesmentioning

confidence: 99%

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The mechanism of receptor‐mediated endocytosis

Smythe

Warren

1991

European Journal of Biochemistry

153

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“…Due to receptor-mediated transcytosis, IgG is sorted away from the degradative pathway to the basolateral plasma membrane. Dissociation of IgG from its receptor can be induced by neutral pH either in transcytotic endosomes [50] or at the basolateral membrane, resulting in IgG release into the basolateral medium. This mechanism is similar to that proposed for IgG transport across rat yolk sac endoderm [31].…”

Section: Mechanism Of Igg Uptake and Transcytosis In Bewo Cellsmentioning

confidence: 99%

IgG transport across trophoblast-derived BeWo cells: a model system to study IgG transport in the placenta

et al. 1999

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In primates, prenatal transfer of IgG from mother to offspring occurs predominantly across the placenta. Although a number of Fcgamma-receptors and IgG binding proteins have been detected in human placental tissue, an involvement of any of these receptors in IgG transport across the syncytiotrophoblast remains to be demonstrated. Therefore, we investigated the mechanism of IgG transcytosis in trophoblast-derived BeWo cells. BeWo cells were not only found to express the MHC class I-related IgG Fc receptor, human FcRn, but also specifically bound fluorescein isothiocyanate (FITC)-labeled human IgG (FITC-hIgG) at the apical surface at mildly acidic pH. The cells preferentially transcytosed FITC-hIgG from the apical to the basolateral side when compared to the fluid-phase marker FITC-dextran and to FITC-hIgG transcytosis in the opposite direction. However, endocytosis of FITC-hIgG at the apical plasma membrane at physiological pH required the continuous presence of FITC-hIgG at concentrations similar to those present in the maternal circulation. These results suggest a mechanism by which IgG is internalized by BeWo cells via fluid-phase endocytosis. Tight binding of IgG to hFcRn may then occur in acidic endosomes, followed by selective sorting into the transcytotic pathway. Thus, the main function of this receptor is to prevent entry of IgG into the degradative pathway in lysosomes.

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Free‐flow electrophoretic analysis of endosome subpopulations of rat hepatocytes

et al. 1997

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The separation of functional early and late endosomes from other cellular compartments by free-flow electrophoresis (FFE) has been previously demonstrated in nonpolarized cells. Here, using 125I-labeled anti-secretory component antibodies ([125I]SC Ab) and FITC-labeled asialoorosomucoid (FITC-ASOR) as markers of the transcytotic and lysosomal pathway, respectively, we demonstrate the separation of three distinct endosome subpopulations from polarized rat hepatocytes. Internalization of both markers at 16 degrees C resulted in their accumulation in a common endosome compartment, indicating that both the transcytotic and the lysosomal pathways are arrested in the sorting early endosome at temperatures below 20 degrees C. After chase of the markers from early endosomes into the transcytotic or the degradative route at 37 degrees C, transcytotic endosomes carrying [125I]SC Ab migrated with an electrophoretic motility between early and late endosomes while late endosomes labeled with FITC-ASOR were deflected more towards the anode than early endosomes. These data indicate that in rat hepatocytes, the transcytotic and lysosomal pathways utilize a common (i.e. early endosomes) and two distinct endosome subpopulations (i.e. transcytotic endosomes, late endosomes) prior to delivering proteins for biliary secretion or lysosomal degradation, respectively.

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Regulation of ATP-Dependent Endosome Acidification

Cited by 5 publications

References 19 publications

The mechanism of receptor‐mediated endocytosis

The mechanism of receptor‐mediated endocytosis

IgG transport across trophoblast-derived BeWo cells: a model system to study IgG transport in the placenta

Free‐flow electrophoretic analysis of endosome subpopulations of rat hepatocytes

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