title: Sprouty4 negatively regulates protein kinase C activation by inhibiting phosphatidylinositol 4,5-biphosphate hydrolysis.
abstract: Sproutys have been shown to negatively regulate growth factor-induced extracellular signal-regulated kinase (ERK) activation, and suggested to be an anti-oncogene. However, molecular mechanism of the suppression has not yet been clarified completely. Sprouty4 inhibits vascular endothelial growth factor (VEGF)-A-induced ERK activation, but not VEGF-C-induced ERK activation. It has been shown that VEGF-A-mediated ERK activation is strongly dependent on protein kinase C (PKC), whereas that by VEGF-C is dependent on Ras. This suggests that Sprouty4 inhibits the PKC pathway more specifically than the Ras pathway. In this study, we confirmed that Sprouty4 suppressed various signals downstream of PKC, such as phosphorylation of MARCKS and protein kinase D (PKD), as well as PKC-dependent nuclear factor (NF)-kappaB activation. Furthermore, Sprouty4 suppressed upstream signals of PKC, such as Ca(2+) mobilization, phosphatidylinositol 4,5-biphosphate (PIP(2)) breakdown and inositol 1,4,5-triphosphate (IP(3)) production in response to VEGF-A. Those effects were dependent on the C-terminal cysteine-rich region, but not on the N-terminal region of Sprouty4, which is critical for the suppression of fibroblast growth factor (FGF)-mediated ERK activation. Sprouty4 overexpression or deletion of the Sprouty4 gene did not affect phospholipase C (PLC) gamma-1 activation, which is an enzyme that catalyzes PIP(2) hydrolysis. Moreover, Sprouty4 inhibited not only VEGF-A-mediated PIP(2) hydrolysis but also inhibited the lysophosphatidic acid (LPA)-induced PIP(2) breakdown that is catalyzed by PLC beta/epsilon activated by G-protein coupled receptor (GPCR). Taken together, Sprouty4 has broader suppression activity for various stimuli than previously thought; it may function as an inhibitor for various types of PLC-dependent signaling as well as for ERK activation.
authors.affiliation: Division of Molecular and Cellular Immunology, Medical Institute of Bioregulation, Kyushu University, Fukuoka, Japan.
authors.forename: T
authors.initials: T
authors.lastname: Ayada
authors.forename: K
authors.initials: K
authors.lastname: Taniguchi
authors.forename: F
authors.initials: F
authors.lastname: Okamoto
authors.forename: R
authors.initials: R
authors.lastname: Kato
authors.forename: S
authors.initials: S
authors.lastname: Komune
authors.forename: G
authors.initials: G
authors.lastname: Takaesu
authors.forename: A
authors.initials: A
authors.lastname: Yoshimura
mesh_terms: D000818:Animals; D002118:Calcium / Q000378:metabolism; D002478:Cells, Cultured; D004789:Enzyme Activation; D048049:Extracellular Signal-Regulated MAP Kinases / Q000378:metabolism; D005346:Fibroblast Growth Factors / Q000494:pharmacology; D005347:Fibroblasts / Q000166:cytology / Q000378:metabolism; D011905:Genes, ras; D006801:Humans; D006868:Hydrolysis; D015544:Inositol 1,4,5-Trisphosphate / Q000378:metabolism; D047908:Intracellular Signaling Peptides and Proteins / Q000378:metabolism / Q000502:physiology*; D008246:Lysophospholipids / Q000494:pharmacology; D008565:Membrane Proteins / Q000378:metabolism; D051379:Mice; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D000076250:Myristoylated Alanine-Rich C Kinase Substrate; D016328:NF-kappa B / Q000235:genetics / Q000378:metabolism; D009419:Nerve Tissue Proteins / Q000502:physiology*; D019269:Phosphatidylinositol 4,5-Diphosphate / Q000037:antagonists & inhibitors* / Q000378:metabolism; D010716:Phosphatidylinositols / Q000378:metabolism; D054801:Phosphoinositide Phospholipase C / Q000378:metabolism; D054799:Phospholipase C beta / Q000378:metabolism; D010766:Phosphorylation; D011493:Protein Kinase C / Q000235:genetics / Q000378:metabolism*; D021381:Protein Transport; D015398:Signal Transduction; D042461:Vascular Endothelial Growth Factor A / Q000378:metabolism
chemical_list: D047908:Intracellular Signaling Peptides and Proteins; D008246:Lysophospholipids; C000619710:MARCKS protein, human; C000619711:Marcks protein, mouse; D008565:Membrane Proteins; D016328:NF-kappa B; D009419:Nerve Tissue Proteins; D019269:Phosphatidylinositol 4,5-Diphosphate; D010716:Phosphatidylinositols; C499038:SPRY4 protein, human; C499037:Spry4 protein, mouse; C467484:VEGFA protein, human; D042461:Vascular Endothelial Growth Factor A; D000076250:Myristoylated Alanine-Rich C Kinase Substrate; D005346:Fibroblast Growth Factors; D015544:Inositol 1,4,5-Trisphosphate; C089212:protein kinase D; D011493:Protein Kinase C; D048049:Extracellular Signal-Regulated MAP Kinases; D020928:Mitogen-Activated Protein Kinases; D054801:Phosphoinositide Phospholipase C; D054799:Phospholipase C beta; C423320:phospholipase C epsilon; C032881:lysophosphatidic acid; D002118:Calcium