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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.

Show MeSH
Long-term internalization of albumin in HepG2 cells. Caveolin-1 and CD63 (late endosomal marker) double labelling on ultrathin–frozen section. Numerous caveolin-1 and CD63 containing multi-vesicular bodies (mvb) are present in the cytoplasm indicating that caveola-mediated endocytosis of albumin resulted in an increased trafficking of caveolae to the classical degradative pathway. CD63 was detected with smaller (d : 10 nm), whereas caveolin-1 was labelled with the larger (d : 15 nm) gold particles. (Arrows show caveolin-1 labelled with larger gold particles). Bars: 200 nm.
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fig04: Long-term internalization of albumin in HepG2 cells. Caveolin-1 and CD63 (late endosomal marker) double labelling on ultrathin–frozen section. Numerous caveolin-1 and CD63 containing multi-vesicular bodies (mvb) are present in the cytoplasm indicating that caveola-mediated endocytosis of albumin resulted in an increased trafficking of caveolae to the classical degradative pathway. CD63 was detected with smaller (d : 10 nm), whereas caveolin-1 was labelled with the larger (d : 15 nm) gold particles. (Arrows show caveolin-1 labelled with larger gold particles). Bars: 200 nm.

Mentions: The sub-cellular distribution of caveolin could provide insights into the endocytotic pathways. Caveolin-1 in many cells is evident on the cell surface and within the Golgi complex, and only partial colocalization can be detected with endosomal markers such as EEA1, a marker of the early sorting endosome [71] or CD63, late endosomal marker [73]. When caveolar endocytosis was provoked by albumin, the number of CD63 and caveolin-1 double-labelled multi-vesicular bodies or late endosomes significantly increased [73]. Studying the long-term internalization of albumin in HepG2 cells, albumin was found to accumulate in large, caveolin-1-positive caveosome-like caveolar clusters. At the same time, the number of caveolin-1 and CD63 containing multi-vesicular bodies significantly increased (Fig. 4) indicating that caveolae-mediated endocytosis of albumin resulted in an increased caveolar trafficking along the classical endosomal degradative pathway [73].


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

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

Long-term internalization of albumin in HepG2 cells. Caveolin-1 and CD63 (late endosomal marker) double labelling on ultrathin–frozen section. Numerous caveolin-1 and CD63 containing multi-vesicular bodies (mvb) are present in the cytoplasm indicating that caveola-mediated endocytosis of albumin resulted in an increased trafficking of caveolae to the classical degradative pathway. CD63 was detected with smaller (d : 10 nm), whereas caveolin-1 was labelled with the larger (d : 15 nm) gold particles. (Arrows show caveolin-1 labelled with larger gold particles). Bars: 200 nm.
© Copyright Policy
Related In: Results  -  Collection

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

fig04: Long-term internalization of albumin in HepG2 cells. Caveolin-1 and CD63 (late endosomal marker) double labelling on ultrathin–frozen section. Numerous caveolin-1 and CD63 containing multi-vesicular bodies (mvb) are present in the cytoplasm indicating that caveola-mediated endocytosis of albumin resulted in an increased trafficking of caveolae to the classical degradative pathway. CD63 was detected with smaller (d : 10 nm), whereas caveolin-1 was labelled with the larger (d : 15 nm) gold particles. (Arrows show caveolin-1 labelled with larger gold particles). Bars: 200 nm.
Mentions: The sub-cellular distribution of caveolin could provide insights into the endocytotic pathways. Caveolin-1 in many cells is evident on the cell surface and within the Golgi complex, and only partial colocalization can be detected with endosomal markers such as EEA1, a marker of the early sorting endosome [71] or CD63, late endosomal marker [73]. When caveolar endocytosis was provoked by albumin, the number of CD63 and caveolin-1 double-labelled multi-vesicular bodies or late endosomes significantly increased [73]. Studying the long-term internalization of albumin in HepG2 cells, albumin was found to accumulate in large, caveolin-1-positive caveosome-like caveolar clusters. At the same time, the number of caveolin-1 and CD63 containing multi-vesicular bodies significantly increased (Fig. 4) indicating that caveolae-mediated endocytosis of albumin resulted in an increased caveolar trafficking along the classical endosomal degradative pathway [73].

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