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. 1983 Dec 1;97(6):1762–1776. doi: 10.1083/jcb.97.6.1762

Rapid acidification of endocytic vesicles containing asialoglycoprotein in cells of a human hepatoma line

PMCID: PMC2112727  PMID: 6315742

Abstract

Acidification of endocytic vesicles has been implicated as a necessary step in various processes including receptor recycling, virus penetration, and the entry of diphtheria toxin into cells. However, there have been few accurate pH measurements in morphologically and biochemically defined endocytic compartments. In this paper, we show that prelysosomal endocytic vesicles in HepG2 human hepatoma cells have an internal pH of approximately 5.4. (We previously reported that similar vesicles in mouse fibroblasts have a pH of 5.0.) The pH values were obtained from the fluorescence excitation profile after internalization of fluorescein labeled asialo-orosomucoid (ASOR). To make fluorescence measurements against the high autofluorescence background, we developed digital image analysis methods for estimating the pH within individual endocytic vesicles or lysosomes. Ultrastructural localization with colloidal gold ASOR demonstrated that the pH measurements were made when ligand was in tubulovesicular structures lacking acid phosphatase activity. Biochemical studies with 125I-ASOR demonstrated that acidification precedes degradation by more than 30 min at 37 degrees C. At 23 degrees C ligand degradation ceases almost entirely, but endocytic vesicle acidification and receptor recycling continue. These results demonstrate that acidification of endocytic vesicles, which causes ligand dissociation, occurs without fusion of endocytic vesicles with lysosomes. Methylamine and monensin raise the pH of endocytic vesicles and cause a ligand-independent loss of receptors. The effects on endocytic vesicle pH are rapidly reversible upon removal of the perturbant, but the effects on cell surface receptors are slowly reversible with methylamine and essentially irreversible with monensin. This suggests that monensin can block receptor recycling at a highly sensitive step beyond the acidification of endocytic vesicles. Taken together with other direct and indirect estimates of endocytic vesicle pH, these studies indicate that endocytic vesicles in many cell types rapidly acidify below pH 5.5, a pH sufficiently acidic to allow receptor-ligand dissociation and the penetration of some toxin chains and enveloped virus nucleocapsids into the cytoplasm.

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Selected References

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  1. Anderson P., Tycko B., Maxfield F., Vilcek J. Effect of primary amines on interferon action. Virology. 1982 Mar;117(2):510–515. doi: 10.1016/0042-6822(82)90491-3. [DOI] [PubMed] [Google Scholar]
  2. Ashwell G., Harford J. Carbohydrate-specific receptors of the liver. Annu Rev Biochem. 1982;51:531–554. doi: 10.1146/annurev.bi.51.070182.002531. [DOI] [PubMed] [Google Scholar]
  3. Ashwell G., Morell A. G. The role of surface carbohydrates in the hepatic recognition and transport of circulating glycoproteins. Adv Enzymol Relat Areas Mol Biol. 1974;41(0):99–128. doi: 10.1002/9780470122860.ch3. [DOI] [PubMed] [Google Scholar]
  4. Basu S. K., Goldstein J. L., Anderson R. G., Brown M. S. Monensin interrupts the recycling of low density lipoprotein receptors in human fibroblasts. Cell. 1981 May;24(2):493–502. doi: 10.1016/0092-8674(81)90340-8. [DOI] [PubMed] [Google Scholar]
  5. Basu S. K., Goldstein J. L., Brown M. S. Characterization of the low density lipoprotein receptor in membranes prepared from human fibroblasts. J Biol Chem. 1978 Jun 10;253(11):3852–3856. [PubMed] [Google Scholar]
  6. Bridges K., Harford J., Ashwell G., Klausner R. D. Fate of receptor and ligand during endocytosis of asialoglycoproteins by isolated hepatocytes. Proc Natl Acad Sci U S A. 1982 Jan;79(2):350–354. doi: 10.1073/pnas.79.2.350. [DOI] [PMC free article] [PubMed] [Google Scholar]
  7. Cuatrecasas P., Illiano G. Purification of neuraminidases from Vibrio Cholerae, Clostridium Perfringens and influenza virus by affinity chromatography. Biochem Biophys Res Commun. 1971 Jul 2;44(1):178–184. doi: 10.1016/s0006-291x(71)80175-4. [DOI] [PubMed] [Google Scholar]
  8. Dunn W. A., Hubbard A. L., Aronson N. N., Jr Low temperature selectively inhibits fusion between pinocytic vesicles and lysosomes during heterophagy of 125I-asialofetuin by the perfused rat liver. J Biol Chem. 1980 Jun 25;255(12):5971–5978. [PubMed] [Google Scholar]
  9. Geuze H. J., Slot J. W., Strous G. J., Lodish H. F., Schwartz A. L. Immunocytochemical localization of the receptor for asialoglycoprotein in rat liver cells. J Cell Biol. 1982 Mar;92(3):865–870. doi: 10.1083/jcb.92.3.865. [DOI] [PMC free article] [PubMed] [Google Scholar]
  10. Geuze H. J., Slot J. W., Strous G. J., Lodish H. F., Schwartz A. L. Intracellular site of asialoglycoprotein receptor-ligand uncoupling: double-label immunoelectron microscopy during receptor-mediated endocytosis. Cell. 1983 Jan;32(1):277–287. doi: 10.1016/0092-8674(83)90518-4. [DOI] [PubMed] [Google Scholar]
  11. Gonzalez-Noriega A., Grubb J. H., Talkad V., Sly W. S. Chloroquine inhibits lysosomal enzyme pinocytosis and enhances lysosomal enzyme secretion by impairing receptor recycling. J Cell Biol. 1980 Jun;85(3):839–852. doi: 10.1083/jcb.85.3.839. [DOI] [PMC free article] [PubMed] [Google Scholar]
  12. Haigler H. T., Maxfield F. R., Willingham M. C., Pastan I. Dansylcadaverine inhibits internalization of 125I-epidermal growth factor in BALB 3T3 cells. J Biol Chem. 1980 Feb 25;255(4):1239–1241. [PubMed] [Google Scholar]
  13. Harford J., Bridges K., Ashwell G., Klausner R. D. Intracellular dissociation of receptor-bound asialoglycoproteins in cultured hepatocytes. A pH-mediated nonlysosomal event. J Biol Chem. 1983 Mar 10;258(5):3191–3197. [PubMed] [Google Scholar]
  14. Heiple J. M., Taylor D. L. pH changes in pinosomes and phagosomes in the ameba, Chaos carolinensis. J Cell Biol. 1982 Jul;94(1):143–149. doi: 10.1083/jcb.94.1.143. [DOI] [PMC free article] [PubMed] [Google Scholar]
  15. Keen J. H., Maxfield F. R., Hardegree M. C., Habig W. H. Receptor-mediated endocytosis of diphtheria toxin by cells in culture. Proc Natl Acad Sci U S A. 1982 May;79(9):2912–2916. doi: 10.1073/pnas.79.9.2912. [DOI] [PMC free article] [PubMed] [Google Scholar]
  16. Marnell M. H., Stookey M., Draper R. K. Monensin blocks the transport of diphtheria toxin to the cell cytoplasm. J Cell Biol. 1982 Apr;93(1):57–62. doi: 10.1083/jcb.93.1.57. [DOI] [PMC free article] [PubMed] [Google Scholar]
  17. Marsh M., Wellsteed J., Kern H., Harms E., Helenius A. Monensin inhibits Semliki Forest virus penetration into culture cells. Proc Natl Acad Sci U S A. 1982 Sep;79(17):5297–5301. doi: 10.1073/pnas.79.17.5297. [DOI] [PMC free article] [PubMed] [Google Scholar]
  18. Maxfield F. R., Schlessinger J., Shechter Y., Pastan I., Willingham M. C. Collection of insulin, EGF and alpha2-macroglobulin in the same patches on the surface of cultured fibroblasts and common internalization. Cell. 1978 Aug;14(4):805–810. doi: 10.1016/0092-8674(78)90336-7. [DOI] [PMC free article] [PubMed] [Google Scholar]
  19. Maxfield F. R. Weak bases and ionophores rapidly and reversibly raise the pH of endocytic vesicles in cultured mouse fibroblasts. J Cell Biol. 1982 Nov;95(2 Pt 1):676–681. doi: 10.1083/jcb.95.2.676. [DOI] [PMC free article] [PubMed] [Google Scholar]
  20. Ohkuma S., Moriyama Y., Takano T. Identification and characterization of a proton pump on lysosomes by fluorescein-isothiocyanate-dextran fluorescence. Proc Natl Acad Sci U S A. 1982 May;79(9):2758–2762. doi: 10.1073/pnas.79.9.2758. [DOI] [PMC free article] [PubMed] [Google Scholar]
  21. Ohkuma S., Poole B. Fluorescence probe measurement of the intralysosomal pH in living cells and the perturbation of pH by various agents. Proc Natl Acad Sci U S A. 1978 Jul;75(7):3327–3331. doi: 10.1073/pnas.75.7.3327. [DOI] [PMC free article] [PubMed] [Google Scholar]
  22. Pastan I. H., Willingham M. C. Journey to the center of the cell: role of the receptosome. Science. 1981 Oct 30;214(4520):504–509. doi: 10.1126/science.6170111. [DOI] [PubMed] [Google Scholar]
  23. Poole B., Ohkuma S. Effect of weak bases on the intralysosomal pH in mouse peritoneal macrophages. J Cell Biol. 1981 Sep;90(3):665–669. doi: 10.1083/jcb.90.3.665. [DOI] [PMC free article] [PubMed] [Google Scholar]
  24. Regoeczi E., Chindemi P. A., Debanne M. T., Charlwood P. A. Partial resialylation of human asialotransferrin type 3 in the rat. Proc Natl Acad Sci U S A. 1982 Apr;79(7):2226–2230. doi: 10.1073/pnas.79.7.2226. [DOI] [PMC free article] [PubMed] [Google Scholar]
  25. Schwartz A. L., Fridovich S. E., Lodish H. F. Kinetics of internalization and recycling of the asialoglycoprotein receptor in a hepatoma cell line. J Biol Chem. 1982 Apr 25;257(8):4230–4237. [PubMed] [Google Scholar]
  26. Strous G. J., Lodish H. F. Intracellular transport of secretory and membrane proteins in hepatoma cells infected by vesicular stomatitis virus. Cell. 1980 Dec;22(3):709–717. doi: 10.1016/0092-8674(80)90547-4. [DOI] [PubMed] [Google Scholar]
  27. Tartakoff A. M. Perturbation of vesicular traffic with the carboxylic ionophore monensin. Cell. 1983 Apr;32(4):1026–1028. doi: 10.1016/0092-8674(83)90286-6. [DOI] [PubMed] [Google Scholar]
  28. Tartakoff A. M., Vassalli P. Plasma cell immunoglobulin secretion: arrest is accompanied by alterations of the golgi complex. J Exp Med. 1977 Nov 1;146(5):1332–1345. doi: 10.1084/jem.146.5.1332. [DOI] [PMC free article] [PubMed] [Google Scholar]
  29. Tietze C., Schlesinger P., Stahl P. Mannose-specific endocytosis receptor of alveolar macrophages: demonstration of two functionally distinct intracellular pools of receptor and their roles in receptor recycling. J Cell Biol. 1982 Feb;92(2):417–424. doi: 10.1083/jcb.92.2.417. [DOI] [PMC free article] [PubMed] [Google Scholar]
  30. Tycko B., Maxfield F. R. Rapid acidification of endocytic vesicles containing alpha 2-macroglobulin. Cell. 1982 Mar;28(3):643–651. doi: 10.1016/0092-8674(82)90219-7. [DOI] [PubMed] [Google Scholar]
  31. Van Leuven F., Cassiman J. J., Van Den Berghe H. Primary amines inhibit recycling of alpha 2M receptors in fibroblasts. Cell. 1980 May;20(1):37–43. doi: 10.1016/0092-8674(80)90232-9. [DOI] [PubMed] [Google Scholar]
  32. WARREN L. The thiobarbituric acid assay of sialic acids. J Biol Chem. 1959 Aug;234(8):1971–1975. [PubMed] [Google Scholar]
  33. Wall D. A., Wilson G., Hubbard A. L. The galactose-specific recognition system of mammalian liver: the route of ligand internalization in rat hepatocytes. Cell. 1980 Aug;21(1):79–93. doi: 10.1016/0092-8674(80)90116-6. [DOI] [PubMed] [Google Scholar]
  34. Weigel P. H., Oka J. A. Endocytosis and degradation mediated by the asialoglycoprotein receptor in isolated rat hepatocytes. J Biol Chem. 1982 Feb 10;257(3):1201–1207. [PubMed] [Google Scholar]
  35. van Renswoude J., Bridges K. R., Harford J. B., Klausner R. D. Receptor-mediated endocytosis of transferrin and the uptake of fe in K562 cells: identification of a nonlysosomal acidic compartment. Proc Natl Acad Sci U S A. 1982 Oct;79(20):6186–6190. doi: 10.1073/pnas.79.20.6186. [DOI] [PMC free article] [PubMed] [Google Scholar]

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