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Endocytosis via caveolae: alternative pathway with distinct cellular compartments to avoid lysosomal degradation?

Kiss AL, Botos E - J. Cell. Mol. Med. (2009)

Bottom Line: Endocytosis--the uptake of extracellular ligands, soluble molecules, protein and lipids from the extracellular surface--is a vital process, comprising multiple mechanisms, including phagocytosis, macropinocytosis, clathrin-dependent and clathrin-independent uptake such as caveolae-mediated and non-caveolar raft-dependent endocytosis.The best-studied endocytotic pathway for internalizing both bulk membrane and specific proteins is the clathrin-mediated endocytosis.We are especially focussing on the intracellular route of caveolae and providing data supporting that caveolar endocytosis can join to the classical endocytotic pathway.

View Article: PubMed Central - PubMed

Affiliation: Department of Human Morphology and Developmental Biology, Semmelweis University, Budapest, Hungary. KissA@ana2.sote.hu

ABSTRACT
Endocytosis--the uptake of extracellular ligands, soluble molecules, protein and lipids from the extracellular surface--is a vital process, comprising multiple mechanisms, including phagocytosis, macropinocytosis, clathrin-dependent and clathrin-independent uptake such as caveolae-mediated and non-caveolar raft-dependent endocytosis. The best-studied endocytotic pathway for internalizing both bulk membrane and specific proteins is the clathrin-mediated endocytosis. Although many papers were published about the caveolar endocytosis, it is still not known whether it represents an alternative pathway with distinct cellular compartments to avoid lysosomal degradation or ligands taken up by caveolae can also be targeted to late endosomes/lysosomes. In this paper, we summarize data available about caveolar endocytosis. We are especially focussing on the intracellular route of caveolae and providing data supporting that caveolar endocytosis can join to the classical endocytotic pathway.

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Related in: MedlinePlus

(A) Stimulated internalization of caveolae results in the appearance of caveola-clusters (stars). (B) and (C) Some of these clusters are in connection with the cell surface through narrow tubular invagination of the plasma membrane. (C) Using anti-caveolin-1 antibody on ultra-thin–frozen sections, these multi-caveolar clusters were always found to be caveolin-positive. (The first antibody was visualized by colloidal gold-conjugated protein-A. The gold particles represent caveolin-1 and the diameter of the gold particles is shown in index.) pm: plasma membrane. Bars: 200 nm.
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fig02: (A) Stimulated internalization of caveolae results in the appearance of caveola-clusters (stars). (B) and (C) Some of these clusters are in connection with the cell surface through narrow tubular invagination of the plasma membrane. (C) Using anti-caveolin-1 antibody on ultra-thin–frozen sections, these multi-caveolar clusters were always found to be caveolin-positive. (The first antibody was visualized by colloidal gold-conjugated protein-A. The gold particles represent caveolin-1 and the diameter of the gold particles is shown in index.) pm: plasma membrane. Bars: 200 nm.

Mentions: The basic question is whether the internalized caveolae can fuse with endosomes and follow the classical endocytotic degradative pathway or the alternative endocytosis involves alternative cellular compartments. Stimulated caveolar internalization is always accompanied by the appearance of grape-like multi-caveolar complexes (Fig. 2A). Studying the entry of SV40 viruses taken up by caveolae, the virus particles were detected in these multi-caveolar complexes of neutral pH, distinct from classical endocytotic compartments [35]. These multi-caveolar complexes never fused with lysosomes; thus, viruses could escape lysosomal degradation. Since these structures were labelled with caveolin-1, they were named caveosomes [35, 68]. Until now, only a few electron microscopical pictures were published about the morphology of these organelles [35, 69].


Endocytosis via caveolae: alternative pathway with distinct cellular compartments to avoid lysosomal degradation?

Kiss AL, Botos E - J. Cell. Mol. Med. (2009)

(A) Stimulated internalization of caveolae results in the appearance of caveola-clusters (stars). (B) and (C) Some of these clusters are in connection with the cell surface through narrow tubular invagination of the plasma membrane. (C) Using anti-caveolin-1 antibody on ultra-thin–frozen sections, these multi-caveolar clusters were always found to be caveolin-positive. (The first antibody was visualized by colloidal gold-conjugated protein-A. The gold particles represent caveolin-1 and the diameter of the gold particles is shown in index.) pm: plasma membrane. Bars: 200 nm.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC4496137&req=5

fig02: (A) Stimulated internalization of caveolae results in the appearance of caveola-clusters (stars). (B) and (C) Some of these clusters are in connection with the cell surface through narrow tubular invagination of the plasma membrane. (C) Using anti-caveolin-1 antibody on ultra-thin–frozen sections, these multi-caveolar clusters were always found to be caveolin-positive. (The first antibody was visualized by colloidal gold-conjugated protein-A. The gold particles represent caveolin-1 and the diameter of the gold particles is shown in index.) pm: plasma membrane. Bars: 200 nm.
Mentions: The basic question is whether the internalized caveolae can fuse with endosomes and follow the classical endocytotic degradative pathway or the alternative endocytosis involves alternative cellular compartments. Stimulated caveolar internalization is always accompanied by the appearance of grape-like multi-caveolar complexes (Fig. 2A). Studying the entry of SV40 viruses taken up by caveolae, the virus particles were detected in these multi-caveolar complexes of neutral pH, distinct from classical endocytotic compartments [35]. These multi-caveolar complexes never fused with lysosomes; thus, viruses could escape lysosomal degradation. Since these structures were labelled with caveolin-1, they were named caveosomes [35, 68]. Until now, only a few electron microscopical pictures were published about the morphology of these organelles [35, 69].

Bottom Line: Endocytosis--the uptake of extracellular ligands, soluble molecules, protein and lipids from the extracellular surface--is a vital process, comprising multiple mechanisms, including phagocytosis, macropinocytosis, clathrin-dependent and clathrin-independent uptake such as caveolae-mediated and non-caveolar raft-dependent endocytosis.The best-studied endocytotic pathway for internalizing both bulk membrane and specific proteins is the clathrin-mediated endocytosis.We are especially focussing on the intracellular route of caveolae and providing data supporting that caveolar endocytosis can join to the classical endocytotic pathway.

View Article: PubMed Central - PubMed

Affiliation: Department of Human Morphology and Developmental Biology, Semmelweis University, Budapest, Hungary. KissA@ana2.sote.hu

ABSTRACT
Endocytosis--the uptake of extracellular ligands, soluble molecules, protein and lipids from the extracellular surface--is a vital process, comprising multiple mechanisms, including phagocytosis, macropinocytosis, clathrin-dependent and clathrin-independent uptake such as caveolae-mediated and non-caveolar raft-dependent endocytosis. The best-studied endocytotic pathway for internalizing both bulk membrane and specific proteins is the clathrin-mediated endocytosis. Although many papers were published about the caveolar endocytosis, it is still not known whether it represents an alternative pathway with distinct cellular compartments to avoid lysosomal degradation or ligands taken up by caveolae can also be targeted to late endosomes/lysosomes. In this paper, we summarize data available about caveolar endocytosis. We are especially focussing on the intracellular route of caveolae and providing data supporting that caveolar endocytosis can join to the classical endocytotic pathway.

Show MeSH
Related in: MedlinePlus