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Mammalian sprouty-1 and -2 are membrane-anchored phosphoprotein inhibitors of growth factor signaling in endothelial cells.

Impagnatiello MA, Weitzer S, Gannon G, Compagni A, Cotten M, Christofori G - J. Cell Biol. (2001)

Bottom Line: Recently, Sprouty, an inhibitor of Drosophila development-associated RTK signaling, has been discovered.They are phosphorylated on serine residues and, upon growth factor stimulation, a subset is recruited to the leading edge of the plasma membrane.The data indicate that mammalian Spry-1 and -2 are membrane-anchored proteins that negatively regulate angiogenesis-associated RTK signaling, possibly in a RTK-specific fashion.

View Article: PubMed Central - PubMed

Affiliation: Research Institute of Molecular Pathology, Dr. Bohr-Gasse 7, A-1030 Vienna, Austria.

ABSTRACT
Growth factor-induced signaling by receptor tyrosine kinases (RTKs) plays a central role in embryonic development and in pathogenesis and, hence, is tightly controlled by several regulatory proteins. Recently, Sprouty, an inhibitor of Drosophila development-associated RTK signaling, has been discovered. Subsequently, four mammalian Sprouty homologues (Spry-1-4) have been identified. Here, we report the functional characterization of two of them, Spry-1 and -2, in endothelial cells. Overexpressed Spry-1 and -2 inhibit fibroblast growth factor- and vascular endothelial growth factor-induced proliferation and differentiation by repressing pathways leading to p42/44 mitogen-activating protein (MAP) kinase activation. In contrast, although epidermal growth factor-induced proliferation of endothelial cells was also inhibited by Spry-1 and -2, activation of p42/44 MAP kinase was not affected. Biochemical and immunofluorescence analysis of endogenous and overexpressed Spry-1 and -2 reveal that both Spry-1 and -2 are anchored to membranes by palmitoylation and associate with caveolin-1 in perinuclear and vesicular structures. They are phosphorylated on serine residues and, upon growth factor stimulation, a subset is recruited to the leading edge of the plasma membrane. The data indicate that mammalian Spry-1 and -2 are membrane-anchored proteins that negatively regulate angiogenesis-associated RTK signaling, possibly in a RTK-specific fashion.

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Amino acid alignment of the four mSpry proteins (mSpry-1–4) with hSpry-2 and DSpry. Dashes indicate spaces introduced to maximize alignment. Shaded residues indicate residues that are identical in at least four of the aligned sequences. A putative Sprouty domain and a putative serine-rich domain are underlined by a dotted line and a gray bar, respectively.
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Figure 1: Amino acid alignment of the four mSpry proteins (mSpry-1–4) with hSpry-2 and DSpry. Dashes indicate spaces introduced to maximize alignment. Shaded residues indicate residues that are identical in at least four of the aligned sequences. A putative Sprouty domain and a putative serine-rich domain are underlined by a dotted line and a gray bar, respectively.

Mentions: ESTs that partially encoded mouse homologues of Sprouty were identified by their homology to hSpry sequences (Hacohen et al. 1998). DNA fragments were amplified by PCR and used to screen a cDNA library generated from gestation day 14.5 mouse embryos. Four different cDNAs were recovered that were highly homologous to DSpry and hSpry and that encoded mSpry-1–4 with calculated molecular masses of 34.4, 34.6, 31.6, and 32.6 kD. All four mSpry proteins contain in their COOH-terminal region a cysteine-rich region with at least 23 cysteines; in the alignment of mSpry, hSpry, and DSpry, this region shows the highest homology (Fig. 1). However, this highly conserved Sprouty domain does not exhibit a significant homology to known functional domains of other proteins. NH2-terminal of the Sprouty domain, all Spry sequences analyzed contain a highly conserved serine-rich region (Fig. 1). No significant homologies between DSpry and mammalian Sprys are apparent at the extreme NH2 and COOH termini. None of the mammalian Sprys contains predicted signal peptides for secretion or putative transmembrane domains.


Mammalian sprouty-1 and -2 are membrane-anchored phosphoprotein inhibitors of growth factor signaling in endothelial cells.

Impagnatiello MA, Weitzer S, Gannon G, Compagni A, Cotten M, Christofori G - J. Cell Biol. (2001)

Amino acid alignment of the four mSpry proteins (mSpry-1–4) with hSpry-2 and DSpry. Dashes indicate spaces introduced to maximize alignment. Shaded residues indicate residues that are identical in at least four of the aligned sequences. A putative Sprouty domain and a putative serine-rich domain are underlined by a dotted line and a gray bar, respectively.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2198812&req=5

Figure 1: Amino acid alignment of the four mSpry proteins (mSpry-1–4) with hSpry-2 and DSpry. Dashes indicate spaces introduced to maximize alignment. Shaded residues indicate residues that are identical in at least four of the aligned sequences. A putative Sprouty domain and a putative serine-rich domain are underlined by a dotted line and a gray bar, respectively.
Mentions: ESTs that partially encoded mouse homologues of Sprouty were identified by their homology to hSpry sequences (Hacohen et al. 1998). DNA fragments were amplified by PCR and used to screen a cDNA library generated from gestation day 14.5 mouse embryos. Four different cDNAs were recovered that were highly homologous to DSpry and hSpry and that encoded mSpry-1–4 with calculated molecular masses of 34.4, 34.6, 31.6, and 32.6 kD. All four mSpry proteins contain in their COOH-terminal region a cysteine-rich region with at least 23 cysteines; in the alignment of mSpry, hSpry, and DSpry, this region shows the highest homology (Fig. 1). However, this highly conserved Sprouty domain does not exhibit a significant homology to known functional domains of other proteins. NH2-terminal of the Sprouty domain, all Spry sequences analyzed contain a highly conserved serine-rich region (Fig. 1). No significant homologies between DSpry and mammalian Sprys are apparent at the extreme NH2 and COOH termini. None of the mammalian Sprys contains predicted signal peptides for secretion or putative transmembrane domains.

Bottom Line: Recently, Sprouty, an inhibitor of Drosophila development-associated RTK signaling, has been discovered.They are phosphorylated on serine residues and, upon growth factor stimulation, a subset is recruited to the leading edge of the plasma membrane.The data indicate that mammalian Spry-1 and -2 are membrane-anchored proteins that negatively regulate angiogenesis-associated RTK signaling, possibly in a RTK-specific fashion.

View Article: PubMed Central - PubMed

Affiliation: Research Institute of Molecular Pathology, Dr. Bohr-Gasse 7, A-1030 Vienna, Austria.

ABSTRACT
Growth factor-induced signaling by receptor tyrosine kinases (RTKs) plays a central role in embryonic development and in pathogenesis and, hence, is tightly controlled by several regulatory proteins. Recently, Sprouty, an inhibitor of Drosophila development-associated RTK signaling, has been discovered. Subsequently, four mammalian Sprouty homologues (Spry-1-4) have been identified. Here, we report the functional characterization of two of them, Spry-1 and -2, in endothelial cells. Overexpressed Spry-1 and -2 inhibit fibroblast growth factor- and vascular endothelial growth factor-induced proliferation and differentiation by repressing pathways leading to p42/44 mitogen-activating protein (MAP) kinase activation. In contrast, although epidermal growth factor-induced proliferation of endothelial cells was also inhibited by Spry-1 and -2, activation of p42/44 MAP kinase was not affected. Biochemical and immunofluorescence analysis of endogenous and overexpressed Spry-1 and -2 reveal that both Spry-1 and -2 are anchored to membranes by palmitoylation and associate with caveolin-1 in perinuclear and vesicular structures. They are phosphorylated on serine residues and, upon growth factor stimulation, a subset is recruited to the leading edge of the plasma membrane. The data indicate that mammalian Spry-1 and -2 are membrane-anchored proteins that negatively regulate angiogenesis-associated RTK signaling, possibly in a RTK-specific fashion.

Show MeSH
Related in: MedlinePlus