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Synergies between Aip1p and capping protein subunits (Acp1p and Acp2p) in clathrin-mediated endocytosis and cell polarization in fission yeast.

Berro J, Pollard TD - Mol. Biol. Cell (2014)

Bottom Line: Capping protein and Aip1p help maintain the high density of actin filaments in meshwork by keeping actin filaments close enough for cross-linking.Our experiments also reveal new cellular functions for Acp1p and Acp2p independent of their capping activity.We identified two independent pathways that control polarization of endocytic sites, one depending on acp2(+) and aip1(+) during interphase and the other independent of acp1(+), acp2(+), and aip1(+) during mitosis.

View Article: PubMed Central - PubMed

Affiliation: Department of Molecular, Cellular and Developmental Biology, Yale University, New Haven, CT 06520-8103 Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT 06520-8103 Nanobiology Institute, Yale University, New Haven, CT 06520-8103 Institut Camille Jordan, UMR CNRS 5208, Université de Lyon, 69622 Villeurbanne-Cedex, France Centre de Génétique et de Physiologie Moléculaire et Cellulaire, UMR CNRS 5534, Université de Lyon, 69622 Villeurbanne-Cedex, France.

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Scale drawings of 10-nm-thick sections of actin filament networks in endocytic patches of wild-type, acp1Δ, and aip1Δ strains at two time points, (left) just before scission of the clathrin-coated pit (t = −1 s) and (right) during disassembly (t = +5 s). The small actin network below the pinched-off wild-type vesicle at t = +5 s represents a part of the network released after severing by ADF/cofilin. Owing to the two-dimensional representation of the three-dimensional meshwork, some filaments cross-linked by fimbrin are not represented in this drawing. Widely spaced filaments in acp1/2Δ cells cannot be cross-linked. Color code: black line, actin filaments; light gray line, plasma membrane; dark gray, clathrin; thick brown wedges, Arp2/3 complex bound to an actin filament; thin brown wedges, inactive Arp2/3 complex; blue “C,” capping protein; red “A,” Aip1p; green connected disks, fimbrin. Actin, fimbrin, and membrane lengths and thicknesses are drawn to scale. The numbers of molecules of active and inactive Arp2/3 complex, capping protein, Aip1p, and fimbrin, and the overall length of actin filaments come from this study, Sirotkin et al. (2010), and Berro et al. (2010). The geometry of the clathrin-coated pit and the pinched-off vesicle are based on Kukulski et al. (2012).
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Figure 7: Scale drawings of 10-nm-thick sections of actin filament networks in endocytic patches of wild-type, acp1Δ, and aip1Δ strains at two time points, (left) just before scission of the clathrin-coated pit (t = −1 s) and (right) during disassembly (t = +5 s). The small actin network below the pinched-off wild-type vesicle at t = +5 s represents a part of the network released after severing by ADF/cofilin. Owing to the two-dimensional representation of the three-dimensional meshwork, some filaments cross-linked by fimbrin are not represented in this drawing. Widely spaced filaments in acp1/2Δ cells cannot be cross-linked. Color code: black line, actin filaments; light gray line, plasma membrane; dark gray, clathrin; thick brown wedges, Arp2/3 complex bound to an actin filament; thin brown wedges, inactive Arp2/3 complex; blue “C,” capping protein; red “A,” Aip1p; green connected disks, fimbrin. Actin, fimbrin, and membrane lengths and thicknesses are drawn to scale. The numbers of molecules of active and inactive Arp2/3 complex, capping protein, Aip1p, and fimbrin, and the overall length of actin filaments come from this study, Sirotkin et al. (2010), and Berro et al. (2010). The geometry of the clathrin-coated pit and the pinched-off vesicle are based on Kukulski et al. (2012).

Mentions: Scale drawings of endocytic patches in wild-type and the mutant cells (Figure 7) summarize our current and previous (Berro et al., 2010; Sirotkin et al., 2010) quantitative microscopy measurements and electron microscopy observations (Idrissi et al., 2008, 2012; Kukulski et al., 2012). These drawings of 15-nm slices include ∼5% of the total volume of patches and are the first quantitatively correct model of endocytic patches in fission yeast.


Synergies between Aip1p and capping protein subunits (Acp1p and Acp2p) in clathrin-mediated endocytosis and cell polarization in fission yeast.

Berro J, Pollard TD - Mol. Biol. Cell (2014)

Scale drawings of 10-nm-thick sections of actin filament networks in endocytic patches of wild-type, acp1Δ, and aip1Δ strains at two time points, (left) just before scission of the clathrin-coated pit (t = −1 s) and (right) during disassembly (t = +5 s). The small actin network below the pinched-off wild-type vesicle at t = +5 s represents a part of the network released after severing by ADF/cofilin. Owing to the two-dimensional representation of the three-dimensional meshwork, some filaments cross-linked by fimbrin are not represented in this drawing. Widely spaced filaments in acp1/2Δ cells cannot be cross-linked. Color code: black line, actin filaments; light gray line, plasma membrane; dark gray, clathrin; thick brown wedges, Arp2/3 complex bound to an actin filament; thin brown wedges, inactive Arp2/3 complex; blue “C,” capping protein; red “A,” Aip1p; green connected disks, fimbrin. Actin, fimbrin, and membrane lengths and thicknesses are drawn to scale. The numbers of molecules of active and inactive Arp2/3 complex, capping protein, Aip1p, and fimbrin, and the overall length of actin filaments come from this study, Sirotkin et al. (2010), and Berro et al. (2010). The geometry of the clathrin-coated pit and the pinched-off vesicle are based on Kukulski et al. (2012).
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Related In: Results  -  Collection

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Figure 7: Scale drawings of 10-nm-thick sections of actin filament networks in endocytic patches of wild-type, acp1Δ, and aip1Δ strains at two time points, (left) just before scission of the clathrin-coated pit (t = −1 s) and (right) during disassembly (t = +5 s). The small actin network below the pinched-off wild-type vesicle at t = +5 s represents a part of the network released after severing by ADF/cofilin. Owing to the two-dimensional representation of the three-dimensional meshwork, some filaments cross-linked by fimbrin are not represented in this drawing. Widely spaced filaments in acp1/2Δ cells cannot be cross-linked. Color code: black line, actin filaments; light gray line, plasma membrane; dark gray, clathrin; thick brown wedges, Arp2/3 complex bound to an actin filament; thin brown wedges, inactive Arp2/3 complex; blue “C,” capping protein; red “A,” Aip1p; green connected disks, fimbrin. Actin, fimbrin, and membrane lengths and thicknesses are drawn to scale. The numbers of molecules of active and inactive Arp2/3 complex, capping protein, Aip1p, and fimbrin, and the overall length of actin filaments come from this study, Sirotkin et al. (2010), and Berro et al. (2010). The geometry of the clathrin-coated pit and the pinched-off vesicle are based on Kukulski et al. (2012).
Mentions: Scale drawings of endocytic patches in wild-type and the mutant cells (Figure 7) summarize our current and previous (Berro et al., 2010; Sirotkin et al., 2010) quantitative microscopy measurements and electron microscopy observations (Idrissi et al., 2008, 2012; Kukulski et al., 2012). These drawings of 15-nm slices include ∼5% of the total volume of patches and are the first quantitatively correct model of endocytic patches in fission yeast.

Bottom Line: Capping protein and Aip1p help maintain the high density of actin filaments in meshwork by keeping actin filaments close enough for cross-linking.Our experiments also reveal new cellular functions for Acp1p and Acp2p independent of their capping activity.We identified two independent pathways that control polarization of endocytic sites, one depending on acp2(+) and aip1(+) during interphase and the other independent of acp1(+), acp2(+), and aip1(+) during mitosis.

View Article: PubMed Central - PubMed

Affiliation: Department of Molecular, Cellular and Developmental Biology, Yale University, New Haven, CT 06520-8103 Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT 06520-8103 Nanobiology Institute, Yale University, New Haven, CT 06520-8103 Institut Camille Jordan, UMR CNRS 5208, Université de Lyon, 69622 Villeurbanne-Cedex, France Centre de Génétique et de Physiologie Moléculaire et Cellulaire, UMR CNRS 5534, Université de Lyon, 69622 Villeurbanne-Cedex, France.

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Related in: MedlinePlus