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Caveolae/raft-dependent endocytosis.

Nabi IR, Le PU - J. Cell Biol. (2003)

Bottom Line: Although caveolae are well-characterized subdomains of glycolipid rafts, their distinctive morphology and association with caveolins has led to their internalization being considered different from that of rafts.In this review, we propose that caveolae and rafts are internalized via a common pathway, caveolae/raft-dependent endocytosis, defined by its clathrin independence, dynamin dependence, and sensitivity to cholesterol depletion.The regulatory role of caveolin-1 and ligand sorting in this complex endocytic pathway are specifically addressed.

View Article: PubMed Central - PubMed

Affiliation: Département de Pathologie et Biologie Cellulaire, Université de Montréal, C.P. 6128, Succursale A, Montréal, Québec, Canada H3C 3J7. ivan.robert.nabi@umontreal.ca

ABSTRACT
Although caveolae are well-characterized subdomains of glycolipid rafts, their distinctive morphology and association with caveolins has led to their internalization being considered different from that of rafts. In this review, we propose that caveolae and rafts are internalized via a common pathway, caveolae/raft-dependent endocytosis, defined by its clathrin independence, dynamin dependence, and sensitivity to cholesterol depletion. The regulatory role of caveolin-1 and ligand sorting in this complex endocytic pathway are specifically addressed.

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Related in: MedlinePlus

Expression of dynaminK44A or caveolin-1 results in the formation of morphologically equivalent caveolar invaginations. v-abl-transformed NIH-3T3 cells that exhibit minimal caveolin expression and few cell surface caveolae were infected with adenoviruses coding for either the dynamin K44A mutant (dynK44A) or caveolin-1 (cav-1), and the cells were then processed for electron microscopy. For details, see Le et al., 2002.
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fig1: Expression of dynaminK44A or caveolin-1 results in the formation of morphologically equivalent caveolar invaginations. v-abl-transformed NIH-3T3 cells that exhibit minimal caveolin expression and few cell surface caveolae were infected with adenoviruses coding for either the dynamin K44A mutant (dynK44A) or caveolin-1 (cav-1), and the cells were then processed for electron microscopy. For details, see Le et al., 2002.

Mentions: In lymphocytes that do not express caveolin, cross-linked GPI-anchored proteins cluster in smooth vesicles morphologically equivalent to caveolae before endocytosis (Deckert et al., 1996). Expression of dynK44A in abl-transformed NIH-3T3 cells that express little caveolin and few caveolae results in the expression of smooth invaginations that are morphologically indistinguishable from caveolae induced in the same cells by expression of caveolin-1 (Fig. 1). The dynK44A-induced smooth invaginations are derived from cholesterol-rich glycolipid raft domains as they are not present in cells treated with methyl-β-cyclodextrin (Le et al., 2002). The fact that these “caveolae” can only be visualized when budding is inhibited indicates that, upon invagination, they exhibit a limited residence time at the plasma membrane. Instability of invaginated rafts at the plasma membrane would necessarily limit morphological detection of these structures, especially in ultrathin electron microscopy sections that represent but a fraction of the total plasma membrane surface. The extent to which, in the absence of caveolin-1, invagination and budding are intrinsic properties of the raft domain remains to be determined. Ligand binding and antibody cross-linking may serve not only to recruit receptors to rafts but also contribute to the formation and internalization of these domains (Parton et al., 1994; Deckert et al., 1996; Verkade et al., 2000; Lamaze et al., 2001; Fivaz et al., 2002).


Caveolae/raft-dependent endocytosis.

Nabi IR, Le PU - J. Cell Biol. (2003)

Expression of dynaminK44A or caveolin-1 results in the formation of morphologically equivalent caveolar invaginations. v-abl-transformed NIH-3T3 cells that exhibit minimal caveolin expression and few cell surface caveolae were infected with adenoviruses coding for either the dynamin K44A mutant (dynK44A) or caveolin-1 (cav-1), and the cells were then processed for electron microscopy. For details, see Le et al., 2002.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2199359&req=5

fig1: Expression of dynaminK44A or caveolin-1 results in the formation of morphologically equivalent caveolar invaginations. v-abl-transformed NIH-3T3 cells that exhibit minimal caveolin expression and few cell surface caveolae were infected with adenoviruses coding for either the dynamin K44A mutant (dynK44A) or caveolin-1 (cav-1), and the cells were then processed for electron microscopy. For details, see Le et al., 2002.
Mentions: In lymphocytes that do not express caveolin, cross-linked GPI-anchored proteins cluster in smooth vesicles morphologically equivalent to caveolae before endocytosis (Deckert et al., 1996). Expression of dynK44A in abl-transformed NIH-3T3 cells that express little caveolin and few caveolae results in the expression of smooth invaginations that are morphologically indistinguishable from caveolae induced in the same cells by expression of caveolin-1 (Fig. 1). The dynK44A-induced smooth invaginations are derived from cholesterol-rich glycolipid raft domains as they are not present in cells treated with methyl-β-cyclodextrin (Le et al., 2002). The fact that these “caveolae” can only be visualized when budding is inhibited indicates that, upon invagination, they exhibit a limited residence time at the plasma membrane. Instability of invaginated rafts at the plasma membrane would necessarily limit morphological detection of these structures, especially in ultrathin electron microscopy sections that represent but a fraction of the total plasma membrane surface. The extent to which, in the absence of caveolin-1, invagination and budding are intrinsic properties of the raft domain remains to be determined. Ligand binding and antibody cross-linking may serve not only to recruit receptors to rafts but also contribute to the formation and internalization of these domains (Parton et al., 1994; Deckert et al., 1996; Verkade et al., 2000; Lamaze et al., 2001; Fivaz et al., 2002).

Bottom Line: Although caveolae are well-characterized subdomains of glycolipid rafts, their distinctive morphology and association with caveolins has led to their internalization being considered different from that of rafts.In this review, we propose that caveolae and rafts are internalized via a common pathway, caveolae/raft-dependent endocytosis, defined by its clathrin independence, dynamin dependence, and sensitivity to cholesterol depletion.The regulatory role of caveolin-1 and ligand sorting in this complex endocytic pathway are specifically addressed.

View Article: PubMed Central - PubMed

Affiliation: Département de Pathologie et Biologie Cellulaire, Université de Montréal, C.P. 6128, Succursale A, Montréal, Québec, Canada H3C 3J7. ivan.robert.nabi@umontreal.ca

ABSTRACT
Although caveolae are well-characterized subdomains of glycolipid rafts, their distinctive morphology and association with caveolins has led to their internalization being considered different from that of rafts. In this review, we propose that caveolae and rafts are internalized via a common pathway, caveolae/raft-dependent endocytosis, defined by its clathrin independence, dynamin dependence, and sensitivity to cholesterol depletion. The regulatory role of caveolin-1 and ligand sorting in this complex endocytic pathway are specifically addressed.

Show MeSH
Related in: MedlinePlus