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A Phosphatidylinositol 3-Kinase-independent Insulin Signaling Pathway to N-WASP/Arp2/3/F-actin Required for GLUT4 Glucose Transporter Recycling*

Open AccessPublished:November 01, 2001DOI:https://doi.org/10.1074/jbc.M108280200
      Recruitment of intracellular glucose transporter 4 (GLUT4) to the plasma membrane of fat and muscle cells in response to insulin requires phosphatidylinositol (PI) 3-kinase as well as a proposed PI 3-kinase-independent pathway leading to activation of the small GTPase TC10. Here we show that in cultured adipocytes insulin causes acute cortical localization of the actin-regulatory neural Wiskott-Aldrich syndrome protein (N-WASP) and actin-related protein-3 (Arp3) as well as cortical F-actin polymerization by a mechanism that is insensitive to the PI 3-kinase inhibitor wortmannin. Expression of the dominant inhibitory N-WASP-ΔWA protein lacking the Arp and actin binding regions attenuates the cortical F-actin rearrangements by insulin in these cells. Remarkably, the N-WASP-ΔWA protein also inhibits insulin action on GLUT4 translocation, indicating dependence of GLUT4 recycling on N-WASP-directed cortical F-actin assembly. TC10 exhibits sequence similarity to Cdc42 and has been reported to bind N-WASP. We show the inhibitory TC10 (T31N) mutant, which abrogates insulin-stimulated GLUT4 translocation and glucose transport, also inhibits both cortical localization of N-WASP and F-actin formation in response to insulin. These findings reveal that N-WASP likely functions downstream of TC10 in a PI 3-kinase-independent insulin signaling pathway to mobilize cortical F-actin, which in turn promotes GLUT4 responsiveness to insulin.
      GLUT4
      glucose transporter 4
      Arp
      actin-related protein
      GFP
      green fluorescent protein
      EGFP
      enhanced GFP
      F-actin
      actin filament
      N-WASP
      neural Wiskott-Aldrich syndrome protein
      PI
      phosphatidylinositol
      FITC
      fluorescein isothiocyanate
      HA
      hemagglutinin
      Insulin stimulates glucose uptake by skeletal muscle and adipose tissues primarily through regulation of the subcellular distribution of the glucose transporter 4 (GLUT4)1 (
      • Czech M.P.
      • Corvera S.
      ,
      • Pessin J.E.
      • Saltiel A.R.
      ). In response to insulin, a fraction of GLUT4 present in intracellular membranes is redistributed to the plasma membrane, resulting in an increase of GLUT4 on the cell surface and enhanced glucose uptake by these cells. This effect of insulin is important in maintaining glucose homeostasis in humans, and impaired insulin action can contribute to the pathogenesis of type 2 diabetes (
      • Shulman G.I.
      ). The precise mechanism by which insulin directs exocytosis of GLUT4-containing membrane vesicles remains obscure. However, it is established that activation of the insulin receptor tyrosine kinase catalyzes tyrosine phosphorylation of insulin receptor substrate proteins that bind to Src-homology 2 domain-containing molecules, including the p85 subunit of phosphatidylinositol 3-kinase (PI 3-kinase) (
      • Virkamaki A.
      • Ueki K.
      • Kahn C.R.
      ,
      • White M.F.
      ). This results in activation of the p110 catalytic subunit of the kinase, which then phosphorylates cellular polyphosphoinositides at the D-3 position, forming signaling molecules such as phosphatidylinositol 3,4,5-trisphosphate. Multiple studies using various pharmacologic inhibitors, overexpression of constitutively active or dominant negative mutants, and microinjection of blocking antibodies have suggested a necessary role of the p85/p110-type PI 3-kinase in insulin-stimulated GLUT4 translocation and glucose transport (
      • Czech M.P.
      • Corvera S.
      ,
      • Pessin J.E.
      • Saltiel A.R.
      ,
      • Cheatham B.
      • Vlahos C.J.
      • Cheatham L.
      • Wang L.
      • Blenis J.
      • Kahn C.R.
      ,
      • Sharma P.M.
      • Egawa K.
      • Huang Y.
      • Martin J.L.
      • Huvar I.
      • Boss G.R.
      • Olefsky J.M.
      ,
      • Martin S.S.
      • Haruta T.
      • Morris A.J.
      • Klippel A.
      • Williams L.T.
      • Olefsky J.M.
      ).
      On the other hand, several lines of evidence suggest the requirement of PI 3-kinase-independent pathway(s) in GLUT4 translocation and glucose transport regulation. For example, treatment of cultured adipocytes with a cell-permeable analog of phosphatidylinositol 3,4,5-trisphosphate failed to mimic the action of insulin on hexose transport (
      • Jiang T.
      • Sweeney G.
      • Rudolf M.T.
      • Klip A.
      • Traynor-Kaplan A.
      • Tsien R.Y.
      ). Furthermore, interleukin-4 and anti-integrin antibodies do not apparently stimulate glucose transport in adipocytes, although these agonists activate PI 3-kinase (
      • Isakoff S.J.
      • Taha C.
      • Rose E.
      • Marcusohn J.
      • Klip A.
      • Skolnik E.Y.
      ,
      • Guilherme A.
      • Czech M.P.
      ). Other studies suggest that both endothelin-1 and physical exercise stimulate glucose uptake independent of PI 3-kinase activation in cultured adipocytes and muscle, respectively (
      • Kanzaki M.
      • Watson R.T.
      • Artemyev N.O.
      • Pessin J.E.
      ,
      • Bose A.
      • Cherniack A.D.
      • Langille S.E.
      • Nicoloro S.M.C.
      • Buxton J.M.
      • Park J.G.
      • Chawla A.
      • Czech M.P.
      ,
      • Lawrence J.T.R.
      • Birnbaum M.J.
      ,
      • Kennedy J.W.
      • Hirshman M.F.
      • Gervino E.V.
      • Ocel J.V.
      • Forse R.A.
      • Hoenig S.J.
      • Aronson D.
      • Goodyear L.J.
      • Horton E.S.
      ). Recent reports indicate that insulin stimulation of GLUT4 translocation requires activation of the small GTPase TC10 through a PI 3-kinase-independent pathway involving the docking of adaptor protein CAP and tyrosine phosphorylation of c-Cbl in adipocytes (
      • Baumann C.A.
      • Ribon V.
      • Kanzaki M.
      • Thurmond D.C.
      • Mora S.
      • Shigematsu S.
      • Bickel P.E.
      • Pessin J.E.
      • Saltiel A.R.
      ,
      • Chiang S.H.
      • Baumann C.A.
      • Kanzaki M.
      • Thurmond D.C.
      • Watson R.T.
      • Neudauer C.L.
      • Macara I.G.
      • Pessin J.E.
      • Saltiel A.R.
      ). The link between TC10 activation and GLUT4 translocation is unresolved (
      • Chiang S.H.
      • Baumann C.A.
      • Kanzaki M.
      • Thurmond D.C.
      • Watson R.T.
      • Neudauer C.L.
      • Macara I.G.
      • Pessin J.E.
      • Saltiel A.R.
      ). Thus, although PI 3-kinase activation and 3′-polyphosphoinositide production appears necessary for insulin to act on glucose transport, other signaling pathway(s) may also be required for optimal GLUT4 regulation by the hormone.
      In searching for such PI 3-kinase-independent signaling elements that may be downstream of TC10, we focused on recent findings from our laboratory (
      • Bose A.
      • Cherniack A.D.
      • Langille S.E.
      • Nicoloro S.M.C.
      • Buxton J.M.
      • Park J.G.
      • Chawla A.
      • Czech M.P.
      ,
      • Emoto M.
      • Langille S.E.
      • Czech M.P.
      ,
      • Guilherme A.
      • Emoto M.
      • Buxton J.M.
      • Bose S.
      • Sabini R.
      • Theurkauf W.E.
      • Leszyk J.
      • Czech M.P.
      ) and others (
      • Tsakiridis T.
      • Vranic M.
      • Klip A.
      ,
      • Wang Q.
      • Bilan P.J.
      • Tsakiridis T.
      • Hinek A.
      • Klip A.
      ,
      • Asahi Y.
      • Hayashi H.
      • Wang L.
      • Ebina Y.
      ,
      • Omata W.
      • Shibata H.
      • Li L.
      • Takata K.
      • Kojima I.
      ,
      • Patki V.
      • Buxton J.
      • Chawla A.
      • Lifshitz L.
      • Fogarty K.
      • Carrington W.
      • Tuft R.
      • Corvera S.
      ,
      • Fletcher L.M.
      • Welsh G.I.
      • Oatey P.B.
      • Tavare J.M.
      ,
      • Olson A.L.
      • Trumbly A.R.
      • Gibson G.V.
      ) linking the microtubule- and actin-based cytoskeleton to recycling of GLUT4-containing vesicles. In particular, insulin elicits actin filament (F-actin) formation (
      • Bose A.
      • Cherniack A.D.
      • Langille S.E.
      • Nicoloro S.M.C.
      • Buxton J.M.
      • Park J.G.
      • Chawla A.
      • Czech M.P.
      ,
      • Emoto M.
      • Langille S.E.
      • Czech M.P.
      ,
      • Guilherme A.
      • Emoto M.
      • Buxton J.M.
      • Bose S.
      • Sabini R.
      • Theurkauf W.E.
      • Leszyk J.
      • Czech M.P.
      ,
      • Tsakiridis T.
      • Vranic M.
      • Klip A.
      ,
      • Wang Q.
      • Bilan P.J.
      • Tsakiridis T.
      • Hinek A.
      • Klip A.
      ,
      • Asahi Y.
      • Hayashi H.
      • Wang L.
      • Ebina Y.
      ,
      • Omata W.
      • Shibata H.
      • Li L.
      • Takata K.
      • Kojima I.
      ,
      • Patki V.
      • Buxton J.
      • Chawla A.
      • Lifshitz L.
      • Fogarty K.
      • Carrington W.
      • Tuft R.
      • Corvera S.
      ,
      • Marcusohn J.
      • Isakoff S.J.
      • Rose E.
      • Symons M.
      • Skolnik E.Y.
      ,
      • Nakashima N.
      • Rose D.W.
      • Xiao S.
      • Egawa K.
      • Martin S.S.
      • Haruta T.
      • Saltiel A.R.
      • Olefsky J.M.
      ), and reagents that cause actin depolymerization inhibit insulin-induced GLUT4 translocation and glucose uptake (
      • Emoto M.
      • Langille S.E.
      • Czech M.P.
      ,
      • Guilherme A.
      • Emoto M.
      • Buxton J.M.
      • Bose S.
      • Sabini R.
      • Theurkauf W.E.
      • Leszyk J.
      • Czech M.P.
      ,
      • Tsakiridis T.
      • Vranic M.
      • Klip A.
      ,
      • Wang Q.
      • Bilan P.J.
      • Tsakiridis T.
      • Hinek A.
      • Klip A.
      ,
      • Asahi Y.
      • Hayashi H.
      • Wang L.
      • Ebina Y.
      ,
      • Omata W.
      • Shibata H.
      • Li L.
      • Takata K.
      • Kojima I.
      ,
      • Patki V.
      • Buxton J.
      • Chawla A.
      • Lifshitz L.
      • Fogarty K.
      • Carrington W.
      • Tuft R.
      • Corvera S.
      ). Thus insulin signaling to polymerize cortical F-actin apparently represents a required pathway for optimal movement or fusion of GLUT4-containing membranes to the cell surface membrane. The present study was designed to test whether this signaling pathway may represent the PI 3-kinase-independent cascade involving the TC10 GTPase proposed to be necessary for insulin action on GLUT4 (
      • Chiang S.H.
      • Baumann C.A.
      • Kanzaki M.
      • Thurmond D.C.
      • Watson R.T.
      • Neudauer C.L.
      • Macara I.G.
      • Pessin J.E.
      • Saltiel A.R.
      ). We report here that acute insulin signaling causes cortical actin polymerization in 3T3-L1 adipocytes secondary to the recruitment of the TC10-interacting protein neural Wiskott-Aldrich syndrome protein (N-WASP) to the cortical regions of these cells. These effects are unaffected by the PI 3-kinase inhibitor wortmannin. N-WASP in turn is known to bind the actin-related protein-2/3 (Arp2/3) complex, which causes actin nucleation and polymerization (
      • Higgs H.N.
      • Pollard T.D.
      ,
      • Takenawa T.
      • Miki H.
      ). We find that dominant negative TC10 (T31N) blocks insulin signaling to N-WASP, while the inhibitory constructs TC10 (T31N) and N-WASP-ΔWA attenuate insulin signaling to both cortical F-actin and GLUT4 translocation to the plasma membrane. These data reveal a PI 3-kinase-independent signaling pathway from the insulin receptor to cortical actin polymerization that is required for optimal GLUT4 glucose transporter regulation.

      DISCUSSION

      A key finding of the present studies is the remarkable contrast between insulin-mediated membrane ruffling versus cortical F-actin formation in their sensitivities to the PI 3-kinase inhibitor wortmannin (Fig. 1). The effect of insulin to cause membrane ruffling requires PI 3-kinase, consistent with many previously reported experiments using either wortmannin, blocking antibodies or dominant negative forms of PI 3-kinase (
      • Martin S.S.
      • Haruta T.
      • Morris A.J.
      • Klippel A.
      • Williams L.T.
      • Olefsky J.M.
      ,
      • Khayat Z.A.
      • Tong P.
      • Yaworsky K.
      • Bloch R.J.
      • Klip A.
      ,
      • Wang Q.
      • Somwar R.
      • Bilan P.J.
      • Liu Z.
      • Jin J.
      • Woodgett J.R.
      • Klip A.
      ,
      • Siddhanta U.
      • McIlroy J.
      • Shah A.
      • Zhang Y.
      • Backer J.M.
      ). Surprisingly, we find the effect of insulin on cortical F-actin formation in 3T3-L1 adipocytes to be insensitive to wortmannin under the same conditions (Fig. 1). This distinction of the membrane ruffling phenomenon compared with modulation of actin dynamics by insulin has apparently been missed in previous studies because the exaggerated F-actin bundles easily observed in membrane ruffles of fibroblasts are indeed inhibited along with the ruffles by wortmannin. In these cells, cortical F-actin is somewhat difficult to detect in the absence of ruffles, although at certain optical planes it can be observed (e.g. Fig.1A, optical plane at the top of CHO-T cells in the presence of wortmannin). However, in insulin-sensitive 3T3-L1 adipocytes the cortical F-actin formed in response to the hormone is readily observed whether or not PI 3-kinase is blocked (Figs. 1B and 2). We also note that this effect of insulin to stimulate cortical F-actin polymerization is best observed when adipocytes are plated sparsely.
      The potential impact of the above findings is magnified by the convergence of recent work (
      • Chiang S.H.
      • Baumann C.A.
      • Kanzaki M.
      • Thurmond D.C.
      • Watson R.T.
      • Neudauer C.L.
      • Macara I.G.
      • Pessin J.E.
      • Saltiel A.R.
      ) implicating a PI 3-kinase-independent pathway leading to TC10 is required in the control of glucose transport by insulin, combined with studies (
      • Bose A.
      • Cherniack A.D.
      • Langille S.E.
      • Nicoloro S.M.C.
      • Buxton J.M.
      • Park J.G.
      • Chawla A.
      • Czech M.P.
      ,
      • Emoto M.
      • Langille S.E.
      • Czech M.P.
      ,
      • Guilherme A.
      • Emoto M.
      • Buxton J.M.
      • Bose S.
      • Sabini R.
      • Theurkauf W.E.
      • Leszyk J.
      • Czech M.P.
      ,
      • Tsakiridis T.
      • Vranic M.
      • Klip A.
      ,
      • Wang Q.
      • Bilan P.J.
      • Tsakiridis T.
      • Hinek A.
      • Klip A.
      ,
      • Asahi Y.
      • Hayashi H.
      • Wang L.
      • Ebina Y.
      ,
      • Omata W.
      • Shibata H.
      • Li L.
      • Takata K.
      • Kojima I.
      ,
      • Patki V.
      • Buxton J.
      • Chawla A.
      • Lifshitz L.
      • Fogarty K.
      • Carrington W.
      • Tuft R.
      • Corvera S.
      ) showing a requirement for intact F-actin in this process. Taken together, the data we obtained in Fig. 1 and these recent findings related to GLUT4 regulation led us to test whether indeed cortical F-actin polymerization may represent the target of this PI 3-kinase-independent insulin signaling. The results presented here strongly support this hypothesis. Insulin stimulates the movements of the TC10 target N-WASP and Arp3 to the cell periphery, even when PI 3-kinase is inhibited (Fig. 2). Furthermore, inhibitory forms of TC10 and N-WASP inhibit both insulin-mediated F-actin formation and GLUT4 translocation (Figs. Figure 3, Figure 4, Figure 5and Ref.
      • Chiang S.H.
      • Baumann C.A.
      • Kanzaki M.
      • Thurmond D.C.
      • Watson R.T.
      • Neudauer C.L.
      • Macara I.G.
      • Pessin J.E.
      • Saltiel A.R.
      ). The specificity of the effect of TC10 (T31N) to inhibit insulin action on F-actin and GLUT4 recycling under conditions where dominant negative cdc42 (T17N) has no effect is striking, since both GTPases can interact with N-WASP in vitro (
      • Higgs H.N.
      • Pollard T.D.
      ,
      • Takenawa T.
      • Miki H.
      ,
      • Rohatgi R.
      • Ma L.
      • Miki H.
      • Lopez M.
      • Kirchhausen T.
      • Takenawa T.
      • Kirschner M.W.
      ,
      • Rohatgi R.
      • Ho H.Y.
      • Kirschner M.W.
      ,
      • Moreau V.
      • Frischknecht F.
      • Reckmann I.
      • Vincentelli R.
      • Rabut G.
      • Stewart D.
      • Way M.
      ,
      • Miki H.
      • Miura K.
      • Takenawa T.
      ,
      • Prehoda K.E.
      • Scott J.A.
      • Mullins R.D.
      • Lim W.A.
      ,
      • Neudauer C.L.
      • Joberty G.
      • Tatsis N.
      • Macara I.G.
      ). This specificity may derive from the recent report that TC10 expression is increased in differentiated 3T3-L1 adipocytes (
      • Imagawa M.
      • Tsuchiya T.
      • Nishihara T.
      ). In addition, this may be also related to the distinct localizations of these proteins whereby TC10 concentrates at the plasma membrane while Cdc42 is predominantly perinuclear (
      • Murphy G.A.
      • Jillian S.A.
      • Michaelson D.
      • Philips M.R.
      • D'Eustachio P.
      • Rush M.G.
      ). That N-WASP may be the physiological target of TC10 in 3T3-L1 adipocytes in a PI 3-kinase-independent signaling pathway is consistent with data in Fig.4 showing inhibitory TC10 (T31N) blocks N-WASP movements triggered by insulin.
      The present findings are consistent with recent studies that document a requirement of intact F-actin for optimal GLUT4 translocation in response to insulin in both primary (
      • Omata W.
      • Shibata H.
      • Li L.
      • Takata K.
      • Kojima I.
      ) and cultured adipocytes (
      • Bose A.
      • Cherniack A.D.
      • Langille S.E.
      • Nicoloro S.M.C.
      • Buxton J.M.
      • Park J.G.
      • Chawla A.
      • Czech M.P.
      ,
      • Emoto M.
      • Langille S.E.
      • Czech M.P.
      ,
      • Guilherme A.
      • Emoto M.
      • Buxton J.M.
      • Bose S.
      • Sabini R.
      • Theurkauf W.E.
      • Leszyk J.
      • Czech M.P.
      ,
      • Wang Q.
      • Bilan P.J.
      • Tsakiridis T.
      • Hinek A.
      • Klip A.
      ,
      • Patki V.
      • Buxton J.
      • Chawla A.
      • Lifshitz L.
      • Fogarty K.
      • Carrington W.
      • Tuft R.
      • Corvera S.
      ). Interestingly, previous findings (
      • Emoto M.
      • Langille S.E.
      • Czech M.P.
      ,
      • Patki V.
      • Buxton J.
      • Chawla A.
      • Lifshitz L.
      • Fogarty K.
      • Carrington W.
      • Tuft R.
      • Corvera S.
      ) indicated the inhibition of insulin-stimulated GLUT4 recycling by actin depolymerization reagents such as latrunculin B is about 50%, similar to our present findings with dominant negative N-WASP (Fig. 5). This partial inhibition suggests that actin rearrangements facilitate GLUT4 movements and optimize efficiency of the translocation process. How might actin filaments near the plasma membrane promote GLUT4-containing membrane recycling? Two possibilities are suggested by studies with other systems involving secretory vesicle or granule movements in response to stimuli. One model invokes the requirement for localized active actin breakdown and remodeling so that incoming membrane vesicles can reach the plasma membrane through the thick barrier of filaments in this region (
      • Vitale M.L.
      • Seward E.P.
      • Trifaro J.M.
      ,
      • Valentijn J.A.
      • Valentijn K.
      • Pastore L.M.
      • Jamieson J.D.
      ). A second model suggests that unconventional myosins act to move membrane vesicles along actin filaments to sites of membrane fusion (
      • Kamal A.
      • Goldstein L.S.
      ). These models are not mutually exclusive. Future work will be necessary to determine whether these or other mechanisms are involved in linking the PI 3-kinase-independent actin regulation described here to movements of vesicles that transport GLUT4 to the plasma membrane.

      Acknowledgments

      We thank Dr. Marc W. Kirschner and Hsin-yi Henry Ho (Harvard Medical School) for providing N-WASP antibody and Dr. Paul Furcinitti and Dr. Masahiro Emoto (University of Massachusetts Medical School) for excellent help on image analysis.

      REFERENCES

        • Czech M.P.
        • Corvera S.
        J. Biol. Chem. 1999; 274: 1865-1868
        • Pessin J.E.
        • Saltiel A.R.
        J. Clin. Invest. 2000; 106: 165-169
        • Shulman G.I.
        J. Clin. Invest. 2000; 106: 171-176
        • Virkamaki A.
        • Ueki K.
        • Kahn C.R.
        J. Clin. Invest. 1999; 103: 931-943
        • White M.F.
        Mol. Cell. Biochem. 1998; 182: 3-11
        • Cheatham B.
        • Vlahos C.J.
        • Cheatham L.
        • Wang L.
        • Blenis J.
        • Kahn C.R.
        Mol. Cell. Biol. 1994; 14: 4902-4911
        • Sharma P.M.
        • Egawa K.
        • Huang Y.
        • Martin J.L.
        • Huvar I.
        • Boss G.R.
        • Olefsky J.M.
        J. Biol. Chem. 1998; 273: 18528-18537
        • Martin S.S.
        • Haruta T.
        • Morris A.J.
        • Klippel A.
        • Williams L.T.
        • Olefsky J.M.
        J. Biol. Chem. 1996; 271: 17605-17608
        • Jiang T.
        • Sweeney G.
        • Rudolf M.T.
        • Klip A.
        • Traynor-Kaplan A.
        • Tsien R.Y.
        J. Biol. Chem. 1998; 273: 11017-11024
        • Isakoff S.J.
        • Taha C.
        • Rose E.
        • Marcusohn J.
        • Klip A.
        • Skolnik E.Y.
        Proc. Natl. Acad. Sci. U. S. A. 1995; 92: 10247-10251
        • Guilherme A.
        • Czech M.P.
        J. Biol. Chem. 1998; 273: 33119-33122
        • Kanzaki M.
        • Watson R.T.
        • Artemyev N.O.
        • Pessin J.E.
        J. Biol. Chem. 2000; 275: 7167-7175
        • Bose A.
        • Cherniack A.D.
        • Langille S.E.
        • Nicoloro S.M.C.
        • Buxton J.M.
        • Park J.G.
        • Chawla A.
        • Czech M.P.
        Mol. Cell. Biol. 2001; 21: 5262-5275
        • Lawrence J.T.R.
        • Birnbaum M.J.
        Mol. Cell. Biol. 2001; 21: 5276-5285
        • Kennedy J.W.
        • Hirshman M.F.
        • Gervino E.V.
        • Ocel J.V.
        • Forse R.A.
        • Hoenig S.J.
        • Aronson D.
        • Goodyear L.J.
        • Horton E.S.
        Diabetes. 1999; 48: 1192-1197
        • Baumann C.A.
        • Ribon V.
        • Kanzaki M.
        • Thurmond D.C.
        • Mora S.
        • Shigematsu S.
        • Bickel P.E.
        • Pessin J.E.
        • Saltiel A.R.
        Nature. 2000; 407: 202-207
        • Chiang S.H.
        • Baumann C.A.
        • Kanzaki M.
        • Thurmond D.C.
        • Watson R.T.
        • Neudauer C.L.
        • Macara I.G.
        • Pessin J.E.
        • Saltiel A.R.
        Nature. 2001; 410: 944-948
        • Emoto M.
        • Langille S.E.
        • Czech M.P.
        J. Biol. Chem. 2001; 276: 10677-10682
        • Guilherme A.
        • Emoto M.
        • Buxton J.M.
        • Bose S.
        • Sabini R.
        • Theurkauf W.E.
        • Leszyk J.
        • Czech M.P.
        J. Biol. Chem. 2000; 275: 38151-38159
        • Tsakiridis T.
        • Vranic M.
        • Klip A.
        J. Biol. Chem. 1994; 269: 29934-29942
        • Wang Q.
        • Bilan P.J.
        • Tsakiridis T.
        • Hinek A.
        • Klip A.
        Biochem. J. 1998; 331: 917-928
        • Asahi Y.
        • Hayashi H.
        • Wang L.
        • Ebina Y.
        J. Med. Invest. 1999; 46: 192-199
        • Omata W.
        • Shibata H.
        • Li L.
        • Takata K.
        • Kojima I.
        Biochem. J. 2000; 346: 321-328
        • Patki V.
        • Buxton J.
        • Chawla A.
        • Lifshitz L.
        • Fogarty K.
        • Carrington W.
        • Tuft R.
        • Corvera S.
        Mol. Biol. Cell. 2001; 12: 129-141
        • Fletcher L.M.
        • Welsh G.I.
        • Oatey P.B.
        • Tavare J.M.
        Biochem. J. 2000; 352: 267-276
        • Olson A.L.
        • Trumbly A.R.
        • Gibson G.V.
        J. Biol. Chem. 2001; 276: 10706-10714
        • Marcusohn J.
        • Isakoff S.J.
        • Rose E.
        • Symons M.
        • Skolnik E.Y.
        Curr. Biol. 1995; 5: 1296-1302
        • Nakashima N.
        • Rose D.W.
        • Xiao S.
        • Egawa K.
        • Martin S.S.
        • Haruta T.
        • Saltiel A.R.
        • Olefsky J.M.
        J. Biol. Chem. 1999; 274: 3001-3008
        • Higgs H.N.
        • Pollard T.D.
        Annu. Rev. Biochem. 2001; 70: 649-676
        • Takenawa T.
        • Miki H.
        J. Cell Sci. 2001; 114: 1801-1809
        • Rohatgi R.
        • Ma L.
        • Miki H.
        • Lopez M.
        • Kirchhausen T.
        • Takenawa T.
        • Kirschner M.W.
        Cell. 1999; 97: 221-231
        • Rohatgi R.
        • Ho H.Y.
        • Kirschner M.W.
        J. Cell Biol. 2000; 150: 1299-1310
        • Langille S.E.
        • Patki V.
        • Klarlund J.K.
        • Buxton J.M.
        • Holik J.J.
        • Chawla A.
        • Corvera S.
        • Czech M.P.
        J. Biol. Chem. 1999; 274: 27099-27104
        • Moreau V.
        • Frischknecht F.
        • Reckmann I.
        • Vincentelli R.
        • Rabut G.
        • Stewart D.
        • Way M.
        Nat. Cell Biol. 2000; 2: 441-448
        • Murphy G.A.
        • Solski P.A.
        • Jillian S.A.
        • Perez de la Ossa P.
        • D'Eustachio P.
        • Der C.J.
        • Rush M.G.
        Oncogene. 1999; 18: 3831-3845
        • Czech M.P.
        • Chawla A.
        • Woon C.W.
        • Buxton J.
        • Armoni M.
        • Tang W.
        • Joly M.
        • Corvera S.
        J. Cell Biol. 1993; 123: 127-135
        • Khayat Z.A.
        • Tong P.
        • Yaworsky K.
        • Bloch R.J.
        • Klip A.
        J. Cell Sci. 2000; 113: 279-290
        • Wang Q.
        • Somwar R.
        • Bilan P.J.
        • Liu Z.
        • Jin J.
        • Woodgett J.R.
        • Klip A.
        Mol. Cell. Biol. 1999; 19: 4008-4018
        • Siddhanta U.
        • McIlroy J.
        • Shah A.
        • Zhang Y.
        • Backer J.M.
        J. Cell Biol. 1998; 143: 1647-1659
        • Miki H.
        • Miura K.
        • Takenawa T.
        EMBO J. 1996; 15: 5326-5335
        • Prehoda K.E.
        • Scott J.A.
        • Mullins R.D.
        • Lim W.A.
        Science. 2000; 290: 801-806
        • Neudauer C.L.
        • Joberty G.
        • Tatsis N.
        • Macara I.G.
        Curr. Biol. 1998; 8: 1151-1160
        • Imagawa M.
        • Tsuchiya T.
        • Nishihara T.
        Biochem. Biophys. Res. Commun. 1999; 254: 299-305
        • Murphy G.A.
        • Jillian S.A.
        • Michaelson D.
        • Philips M.R.
        • D'Eustachio P.
        • Rush M.G.
        Cell Growth Differ. 2001; 12: 157-167
        • Vitale M.L.
        • Seward E.P.
        • Trifaro J.M.
        Neuron. 1995; 14: 353-363
        • Valentijn J.A.
        • Valentijn K.
        • Pastore L.M.
        • Jamieson J.D.
        Proc. Natl. Acad. Sci. U. S. A. 2000; 97: 1091-1095
        • Kamal A.
        • Goldstein L.S.
        Curr. Opin. Cell Biol. 2000; 12: 503-508