SNX9 Couples Actin Assembly to Phosphoinositide Signals and Is Required for Membrane Remodeling during Endocytosis

Yarar, Defne; Waterman‐Storer, Clare M.; Schmid, Sandra L.

doi:10.1016/j.devcel.2007.04.014

Cited by 189 publications

(257 citation statements)

References 49 publications

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“…Snx9 has been implicated in endocytosis, macropinocytosis, phagocytosis (particularly of apoptotic cells), and mitosis (18)(19)(20)(21). The enrichment of PI(4,5)P 2 at the plasma membrane clearly highlights the importance of that location for the Snx9 pathway, and PI(3)P is known to be produced on macropinosomes, phagosomes, and endosomes (22)(23)(24).…”

Section: Discussionmentioning

confidence: 99%

“…Many of these proteins probably act redundantly; few have been assayed for their role in actin nucleation. Sorting nexin 9 (Snx9) is of particular interest, because it has previously been shown to both stimulate N-WASP activation of Arp2/3 complex and to have a Phox homology domain that was implicated in binding to PI(3)P, although this domain seems to act somewhat promiscuously (18). To test whether Snx9 could be involved in transducing the signal from PI(3)P to N-WASP and potentially activate the Arp2/3 complex in frog egg extracts we depleted Snx9 from the extract (Fig.…”

Section: Differences In Actin Assembly Between Liposomes and Supportedmentioning

confidence: 99%

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Phosphoinositides and membrane curvature switch the mode of actin polymerization via selective recruitment of toca-1 and Snx9

Gallop

Walrant

Cantley

et al. 2013

Proc. Natl. Acad. Sci. U.S.A.

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The membrane-cytosol interface is the major locus of control of actin polymerization. At this interface, phosphoinositides act as second messengers to recruit membrane-binding proteins. We show that curved membranes, but not flat ones, can use phosphatidylinositol 3-phosphate [PI(3)P] along with phosphatidylinositol 4,5-bisphosphate [PI(4,5)P 2 ] to stimulate actin polymerization. In this case, actin polymerization requires the small GTPase cell cycle division 42 (Cdc42), the nucleation-promoting factor neural Wiskott-Aldrich syndrome protein (N-WASP) and the actin nucleator the actin-related protein (Arp) 2/3 complex. In liposomes containing PI(4,5)P2 as the sole phosphoinositide, actin polymerization requires transducer of Cdc42 activation-1 (toca-1). In the presence of phosphatidylinositol 3-phosphate, polymerization is both more efficient and independent of toca-1. Under these conditions, sorting nexin 9 (Snx9) can be implicated as a specific adaptor that replaces toca-1 to mobilize neural Wiskott-Aldrich syndrome protein and the Arp2/3 complex. This switch in phosphoinositide and adaptor specificity for actin polymerization from membranes has implications for how different types of actin structures are generated at precise times and locations in the cell.T he original discovery of actin as the scaffold in muscle upon which myosin exerts its force obscured for some time that a major role of actin in nonmuscle cells involves its intimate association with cellular membranes. Through morphological studies of the actin cytoskeleton, the close association of actin polymerization and the specification of actin polarity with respect to membranes came to the fore. As the regulatory biochemistry of actin was unraveled, a striking role for regulators with substantial, and regulated, residence in the membrane, such as phosphoinositides and small G proteins, emerged. In the past decades, the extraordinary dynamics of the cytoskeleton as well as the equally extraordinary dynamics of membrane traffic have become centerpieces of cell biological understanding. That an important structural linkage between the dynamics of the membrane and cytoskeleton exists is evident, but how actin regulators are targeted to specific membrane sites is less clear.Phosphoinositides are chemically dynamic lipids that are important upstream regulators of actin assembly (1-3); they can exert their effects through specific protein domains, such as the FYVE (Fab1, YOTB, Vac1, EEA1) domain in EEA1 (early endosome antigen 1) that binds phosphatidylinositol 3-phosphate [PI(3)P]; the pleckstrin homology (PH) domain in Akt that binds phosphatidylinositol (3,4) bisphosphate; and the PH domain in phospholipase Cδ that binds phosphatidylinositol (4,5) bisphosphate [PI(4,5)P 2 ]. The actin polymerization machinery is vast and complex, consisting of nucleators, transducers, cappers, bundlers, and more, many of which are regulated by phosphoinositides (4, 5) and are good candidates to test for biochemical coordination of membrane processes. The fluidity and ...

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Section: Discussionmentioning

confidence: 99%

Section: Differences In Actin Assembly Between Liposomes and Supportedmentioning

confidence: 99%

Phosphoinositides and membrane curvature switch the mode of actin polymerization via selective recruitment of toca-1 and Snx9

Gallop

Walrant

Cantley

et al. 2013

Proc. Natl. Acad. Sci. U.S.A.

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“…Because SNX18 interacts with N-WASP, a regulator of the actin cytoskeleton, and actin, it raises the possibility that SNX18 has a role in actin-cytoskeleton-mediated endocytosis, such as fluid-phase endocytosis, as does SNX9 (Yarar et al, 2007). We could detect 1748 Journal of Cell Science 123 (10) SNX18 in circular dorsal ruffles and membrane ruffles at the cell periphery of NIH3T3 cells after treatment with platelet-derived growth factor (PDGF).…”

Section: Discussionmentioning

confidence: 99%

SNX18 shares a redundant role with SNX9 and modulates endocytic trafficking at the plasma membrane

Park

Kim

Lee

et al. 2010

Journal of Cell Science

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SNX18 and SNX9 are members of a subfamily of SNX (sorting nexin) proteins with the same domain structure. Although a recent report showed that SNX18 and SNX9 localize differently in cells and appear to function in different trafficking pathways, concrete evidence regarding whether they act together or separately in intracellular trafficking is still lacking. Here, we show that SNX18 has a similar role to SNX9 in endocytic trafficking at the plasma membrane, rather than having a distinct role. SNX18 and SNX9 are expressed together in most cell lines, but to a different extent. Like SNX9, SNX18 interacts with dynamin and stimulates the basal GTPase activity of dynamin. It also interacts with neuronal Wiskott-Aldrich syndrome protein (N-WASP) and synaptojanin, as does SNX9. SNX18 and SNX9 can form a heterodimer and colocalize in tubular membrane structures. Depletion of SNX18 by small hairpin RNA inhibited transferrin uptake. SNX18 successfully compensates for SNX9 deficiency during clathrin-mediated endocytosis and vice versa. Total internal reflection fluorescence microscopy in living cells shows that a transient burst of SNX18 recruitment to clathrin-coated pits coincides spatiotemporally with a burst of dynamin and SNX9. Taken together, our results suggest that SNX18 functions with SNX9 in multiple pathways of endocytosis at the plasma membrane and that they are functionally redundant.

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“…SNX4 associates with dynein/dynactin through its interaction with the dynein light chain 1-binding protein KIBRA and is required for transport of the transferrin receptor between peripheral early endosomes and the juxtanuclear endocytic recycling compartment [18]. SNX9, in contrast, senses phosphatidylinositol 4,5-bisphosphate signals at the plasma membrane and couples actin dynamics with membrane remodeling during clathrin-mediated endocytosis, dorsal ruffle formation and clathrin-independent fluid phase endocytosis [19].…”

Section: Introductionmentioning

confidence: 99%

The retromer component SNX6 interacts with dynactin p150Glued and mediates endosome-to-TGN transport

et al. 2009

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The retromer is a protein complex that mediates retrograde transport of transmembrane cargoes from endosomes to the trans-Golgi network (TGN). It is comprised of a cargo-selection subcomplex of Vps26, Vps29 and Vps35 and a membrane-binding coat subcomplex of sorting nexins (SNXs). Previous studies identified SNX1/2 as one of the components of the SNX subcomplex, and SNX5/6 as candidates for the second SNX. How the retromer-associated cargoes are recognized and transported by molecular motors are largely unknown. In this study, we found that one of SNX1/2's dimerization partners, SNX6, interacts with the p150 Glued subunit of the dynein/dynactin motor complex. We present evidence that SNX6 is a component of the retromer, and that recruitment of the motor complex to the membrane-associated retromer requires the SNX6-p150 Glued interaction. Disruption of the SNX6-p150 Glued interaction causes failure in formation and detachment of the tubulovesicular sorting structures from endosomes and results in block of CI-MPR retrieval from endosomes to the TGN. These observations indicate that in addition to SNX1/2, SNX6 in association with the dynein/dynactin complex drives the formation and movement of tubular retrograde intermediates.

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SNX9 Couples Actin Assembly to Phosphoinositide Signals and Is Required for Membrane Remodeling during Endocytosis

Cited by 189 publications

References 49 publications

Phosphoinositides and membrane curvature switch the mode of actin polymerization via selective recruitment of toca-1 and Snx9

Phosphoinositides and membrane curvature switch the mode of actin polymerization via selective recruitment of toca-1 and Snx9

SNX18 shares a redundant role with SNX9 and modulates endocytic trafficking at the plasma membrane

The retromer component SNX6 interacts with dynactin p150Glued and mediates endosome-to-TGN transport

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