Sprouty regulates cell migration by inhibiting the activation of Rac1 GTPase

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Abstract

Sprouty (SPRY) protein negatively modulates fibroblast growth factor and epidermal growth factor actions. We showed that human SPRY2 inhibits cell growth and migration in response to serum and several growth factors. Using rat intestinal epithelial (IEC-6) cells, we investigated the involvement of the Rho family of GTPases, RhoA, Rac1, and cdc42 in SPRY2-mediated inhibition of cell migration and proliferation. The ability of TAT-tagged SPRY2 to inhibit proliferation and migration of IEC-6 cells transfected with constitutively active mutants of RhoA(G14V), Rac1(G12V), and cdc42 (F28L) was determined. Constitutively active RhoA(G14V), Rac1(G12V), or cdc42(F28L) did not protect cells from the anti-proliferative actions of TAT-SPRY2. The ability of TAT-hSPRY2 to inhibit migration was not altered by of RhoA(G14V) and cdc42(F28L). However, Rac1(G12V) obliterated the ability of SPRY2 to inhibit cell autonomous or serum-induced migration. Also, the activation of endogenous Rac1 was attenuated by TAT-SPRY2. Thus, SPRY2 mediates its anti-migratory actions by inhibiting Rac1 activation.

Section snippets

Materials and methods

Cell culture. Rat intestinal epithelial (IEC6) cells over-expressing constitutively active Rac1, and Cdc42 in pMX-IRES-GFP were generated by transfecting the cells with plasmids pMX-IRES-GFP-G12V-Rac1 and pMX-IRES-GFP-F28L-Cdc42, respectively, as described previously [25]. Control cells were transfected with the empty plasmid in pMX-IRES-GFP. PMX-IRES-GFP constructs to express the Rho family of G proteins were the generous gift of Dr. Yi Zheng (Cincinnati Children’s Hospital). Cells expressing

Results and discussion

Previous studies of Lim et al. [15] and from our laboratory [11] have demonstrated that when cells are activated by mitogens such as epidermal growth factor, the SPRY2 protein is translocated from microtubules to the membrane ruffles. Indeed, the deletion of the membrane translocation domain in SPRY2 obliterates the ability of the protein to inhibit cell migration and proliferation [11]. The formation of membrane ruffles, cell shape changes, lamellipodia formation, and cytoskeletal changes are

Acknowledgments

This work was supported by NIH Grants HL48308 (to T.B.P.) and DK52784 (to L.R.J.). We thank Dr. Yi Zheng for the generous gift of the plasmid constructs for the Rho GTPases as well as GST-PAK1 and GST-WASP. We also thank Mr. David Neblett for technical assistance with some of the experiments.

References (38)

Cited by (32)

  • Sprouty gain of function disrupts lens cellular processes and growth by restricting RTK signaling

    2015, Developmental Biology
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    Aqueous and vitreous humors also contain MMPs (Brown et al., 1994; De La Paz et al., 1998; Huang et al., 1996), with MMP-9 increasing dramatically in the humor (Huang et al., 1996; Brown et al., 1994; Kosano et al., 1999) of patients with proliferative diabetic retinopathy, or following cataract surgery. As noted earlier, given that Rac1 GTPase activity has been shown to play an essential role in lens ECM turnover (Maddala et al., 2011) and Spry2 can limit Rac1 activation (Poppleton et al., 2004), this may be the contributing mechanism to the lens capsule rupture. It would be interesting to identify other Spry targets that influence ECM breakdown or remodeling.

  • Regulation of cellular levels of sprouty2 protein by prolyl hydroxylase domain and von Hippel-Lindau proteins

    2011, Journal of Biological Chemistry
    Citation Excerpt :

    During development, the expression of Spry proteins is augmented at the centers of growth factor signaling such as periphery of limb buds and tips of developing trachea or blood vessels to oppose the actions of growth factors in a negative-feedback manner (3). Previous findings have demonstrated that Spry proteins regulate cell migration and proliferation in response to a number of growth factors (8–13). In keeping with the anti-migratory and anti-proliferative actions of Spry proteins, the levels of Spry1 and Spry2 have been shown to be decreased in breast, hepatocellular, prostate, lung, and colon cancers (14–20), and overexpression of Spry2 decreases formation of lung tumors (21).

  • HECT domain-containing E3 ubiquitin ligase Nedd4 interacts with and ubiquitinates sprouty2

    2010, Journal of Biological Chemistry
    Citation Excerpt :

    For co-IP and pulldown experiments HA- or FLAG-tagged Spry constructs were transfected with or without C867S T7-rNedd4 in HEK293T cells (750,000 cells/60-mm dish). After 48 h, cells were placed on ice, media was removed, washed twice with ice-cold PBS before lysing in 400 μl of lysis buffer as described (18). About 500 μg of cell lysate was used to IP Spry proteins using 1 μg each of the relevant antibody for 2 h at 4 °C.

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1

Present address: Department of Developmental Neurobiology, St. Jude Children’s Research Hospital, Memphis, TN 38105, USA.

2

Present address: St. Mary’s School, Memphis, TN 38119, USA.

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