Polymeric IgA and Galactose-Specific Pathways in Rat Hepatocytes: Evidence for Intracellular Ligand Sorting

Courtoy, Pierre J.; Quintart, J.; Limet, J N; Roe, C. De; Baudhuin, Pierre

doi:10.1007/978-1-4615-6904-6_6

Cited by 22 publications

(14 citation statements)

References 116 publications

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“…In addition, pIgA and galactosylated proteins, when internalized for short times, were found at the same density in sucrose [lo] or Ficoll gradients [15]. Density shift assays have confirmed the colocalization of galactosylated proteins and pIgA within minutes after uptake [12,19,23,521. Finally, Barr et al [21] denionstrated that ASOR internalized for 2 rnin and pIgR were present in vesicles immunoisolated with anti-ASGP-R antibody.…”

Section: Discussionmentioning

confidence: 97%

“…The lysosomal and transcytotic routes can be labeled by the hepatocyte-specific ligands asialoglycoproteins (ASGP; [6, 71) and polymeric immunoglobulin A (pIgA; [8]), respectively. Morphological and biochemical approaches demonstrated that both pathways involve distinct endosome subpopulations differing in their density, shape, size, membrane composition, intracellular localization, function and internal pH [9-211. ASGP and pIgA enter the cell after binding to their respective receptors present at the sinusoidal plasma membrane [9,[22][23][24] via coated pits and vesicles. Both markers are then delivered to an early endosome, where they colocalize although pIgA is found predominantly in the tubular and ASGP in the vesicular elements of this compartment [9,111.…”

Section: Introductionmentioning

confidence: 99%

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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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Section: Discussionmentioning

confidence: 97%

Section: Introductionmentioning

confidence: 99%

Free‐flow electrophoretic analysis of endosome subpopulations of rat hepatocytes

et al. 1997

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“…The observation of lateral sorting and exclusion of ASGP-Rs from vesicles must be accompanied by a countercurrent movement of proteins into the vesicle membranes, since secretory vesicles (e.g., reference 32) and CURL vesicles (9,24,48) possess their own characteristic membrane proteins. We and others have described a special class of CURL vesicles derived from tubules in liver cells that are involved in receptor-mediated transport of polymeric IgA (6,17,28) but contain little ASGP-R (17). Additional high resolution im-munocytochemistry will aid in elucidating possible sorting pathways of specific vesicular membrane proteins.…”

Section: Discussionmentioning

confidence: 99%

Membranes of sorting organelles display lateral heterogeneity in receptor distribution.

Geuze¹,

Slot²,

Schwartz³

1987

The Journal of Cell Biology

148

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Abstract. This study describes the distribution of an intrinsic membrane protein, the asialoglycoprotein receptor (ASGP-R) in the trans-Golgi reticulum and compartment of uncoupling receptor and ligand (CURL) of rat liver cells. Using quantitative immunogold electron microscopy and membrane length measurements, we showed lateral nonhomogeneity of receptors in the membranes of trans-Golgi reticulum and CURL, in particular in the membranes of secretory vesicles (identified by their content of albumin and very low density lipoprotein particles) and of CURL vesicles (endosomes), including multivesicular bodies. The characteristic tubulovesicular morphology of both sorting organelles defines the transition of receptor-rich tubular membrane and the receptor-poor limiting membrane of the attached vesicles. There was a direct relationship between the size of the secretory and CURL vesicles and the density of ASGP-Rs in their membranes. Receptor density in the smallest vesicles was similar to that found in adjacent continuous tubules. The larger the vesicles, the less receptor was detectable in their membranes. We propose that the receptor molecules are excluded from the vesicle membranes by dynamic lateral redistribution. Nonrandom receptor distribution in the CURL vesicle membranes was present even at the multivesicular body stage. These observations strongly suggest the existence of barriers to ASGP-R diffusion at the junctions of tubules and vesicles. In addition, our observations suggest that ASGP-Rs are transported to the plasma membrane via a mechanism other than the normal secretory pathway.

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“…Besides its specificity for glycans with terminal galactose residues, the properties of the ASGP-r as an endocytotic receptor have drawn much attention. In fact, it became an important model system for cell biologists studying receptor-mediated endocytosis Bridges et al, 1982;Connolly et al, 1982;Courtoy et al, 1985;Harford and Ashwell, 1985;Harford et af., 1984), as reviewed by and Weigel (1993).…”

Section: Hepatic Galactose Receptormentioning

confidence: 99%

Sialic Acids in Molecular and Cellular Interactions

Kelm

Schauer

1997

International Review of Cytology

429

348

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Polymeric IgA and Galactose-Specific Pathways in Rat Hepatocytes: Evidence for Intracellular Ligand Sorting

Cited by 22 publications

References 116 publications

Free‐flow electrophoretic analysis of endosome subpopulations of rat hepatocytes

Free‐flow electrophoretic analysis of endosome subpopulations of rat hepatocytes

Membranes of sorting organelles display lateral heterogeneity in receptor distribution.

Sialic Acids in Molecular and Cellular Interactions

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