title: Human sprouty 4, a new ras antagonist on 5q31, interacts with the dual specificity kinase TESK1.
abstract: The Drosophila melanogaster protein sprouty is induced upon fibroblast growth factor (FGF)- and epidermal growth factor (EGF)-receptor tyrosine kinase activation and acts as an inhibitor of the ras/MAP kinase pathway downstream of these receptors. By differential display RT-PCR of activated vs. resting umbilical artery smooth muscle cells (SMCs) we detected a new human sprouty gene, which we designated human sprouty 4 (hspry4) based on its homology with murine sprouty 4. Hspry4 is widely expressed and Northern blots indicate that different isoforms of hspry4 are induced upon cellular activation. The hspry4 gene maps to 5q31.3. It encodes a protein of 322 amino acids, which, in support of a modulating role in signal transduction, contains a prototypic cysteine-rich region, three, potentially Src homology 3 (SH3) binding, proline-rich regions and a PEST sequence. This new sprouty orthologue can suppress the insulin- and EGF-receptor transduced MAP kinase signaling pathway, but fails to inhibit MAP kinase activation by constitutively active V12 ras. Hspry4 appears to impair the formation of active GTP-ras and exert its activity at the level of wild-type ras or upstream thereof. In a yeast two-hybrid screen, using hspry4 as bait, testicular protein kinase 1 (TESK1) was identified from a human fetal liver cDNA library as a partner of hspry4. The hspry4-TESK1 interaction was confirmed by coimmunoprecipitation experiments and increases by growth factor stimulation. The two proteins colocalize in apparent cytoplasmic vesicles and do not show substantial translocation to the plasma membrane upon receptor tyrosine kinase stimulation.
authors.affiliation: Departments of Biochemistry, Academic Medical Center, University of Amsterdam, The Netherlands. o.c.leeksma@amc.uva.nl
authors.forename: Onno C
authors.initials: OC
authors.lastname: Leeksma
authors.forename: Tanja A E
authors.initials: TA
authors.lastname: Van Achterberg
authors.forename: Yoshikazu
authors.initials: Y
authors.lastname: Tsumura
authors.forename: Jiro
authors.initials: J
authors.lastname: Toshima
authors.forename: Eric
authors.initials: E
authors.lastname: Eldering
authors.forename: Wilma G M
authors.initials: WG
authors.lastname: Kroes
authors.forename: Clemens
authors.initials: C
authors.lastname: Mellink
authors.forename: Marcel
authors.initials: M
authors.lastname: Spaargaren
authors.forename: Kensaku
authors.initials: K
authors.lastname: Mizuno
authors.forename: Hans
authors.initials: H
authors.lastname: Pannekoek
authors.forename: Carlie J M
authors.initials: CJ
authors.lastname: de Vries
mesh_terms: D016475:3T3 Cells; D051339:Actin Depolymerizing Factors; D000199:Actins / Q000378:metabolism; D000595:Amino Acid Sequence; D000818:Animals; D019556:COS Cells; D002460:Cell Line; D002478:Cells, Cultured; D002874:Chromosome Mapping; D002895:Chromosomes, Human, Pair 5; D003001:Cloning, Molecular; D066246:ErbB Receptors / Q000037:antagonists & inhibitors; D006367:HeLa Cells; D006801:Humans; D007329:Insulin Antagonists; D016023:Integrins / Q000378:metabolism; D047908:Intracellular Signaling Peptides and Proteins; D008297:Male; D051379:Mice; D008840:Microfilament Proteins / Q000378:metabolism; D008969:Molecular Sequence Data; D009124:Muscle Proteins / Q000378:metabolism; D009419:Nerve Tissue Proteins; D011485:Protein Binding; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism*; D011506:Proteins / Q000235:genetics* / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D015398:Signal Transduction; D013737:Testis / Q000201:enzymology; D018631:ras Proteins / Q000037:antagonists & inhibitors
chemical_list: D051339:Actin Depolymerizing Factors; D000199:Actins; D007329:Insulin Antagonists; D016023:Integrins; D047908:Intracellular Signaling Peptides and Proteins; D008840:Microfilament Proteins; D009124:Muscle Proteins; D009419:Nerve Tissue Proteins; D011506:Proteins; D012333:RNA, Messenger; C499038:SPRY4 protein, human; C097507:testis-specific protein kinase 1; D066246:ErbB Receptors; D017346:Protein Serine-Threonine Kinases; D018631:ras Proteins