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Molecular and Cellular Biology, October 2008, p. 5899-5911, Vol. 28, No. 19
0270-7306/08/$08.00+0 doi:10.1128/MCB.00394-08
Copyright © 2008, American Society for Microbiology. All Rights Reserved.
,
Silvia Turró,1
Ariadna Laguna,1 and
Susana de la Luna1,2*
Genes and Disease Program, Center for Genomic Regulation (CRG), UPF, and Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER-ISCIII), Barcelona, Spain,1 Institució Catalana de Recerca i Estudis Avançats (ICREA), Barcelona, Spain2
Received 7 March 2008/ Returned for modification 15 April 2008/ Accepted 23 July 2008
Raf-MEK-extracellular signal-regulated kinase (Erk) signaling initiated by growth factor-engaged receptor tyrosine kinases (RTKs) is modulated by an intricate network of positive and negative feedback loops which determine the specificity and spatiotemporal characteristics of the intracellular signal. Well-known antagonists of RTK signaling are the Sprouty proteins. The activity of Sprouty proteins is modulated by phosphorylation. However, little is known about the kinases responsible for these posttranslational modifications. We identify DYRK1A as one of the protein kinases of Sprouty2. We show that DYRK1A interacts with and regulates the phosphorylation status of Sprouty2. Moreover, we identify Thr75 on Sprouty2 as a DYRK1A phosphorylation site in vitro and in vivo. This site is functional, since its mutation enhanced the repressive function of Sprouty2 on fibroblast growth factor (FGF)-induced Erk signaling. Further supporting the idea of a functional interaction, DYRK1A and Sprouty2 are present in protein complexes in mouse brain, where their expression overlaps in several structures. Moreover, both proteins copurify with the synaptic plasma membrane fraction of a crude synaptosomal preparation and colocalize in growth cones, pointing to a role in nerve terminals. Our results suggest, therefore, that DYRK1A positively regulates FGF-mitogen-activated protein kinase signaling by phosphorylation-dependent impairment of the inhibitory activity of Sprouty2.
Published ahead of print on 4 August 2008.
Supplemental material for this article may be found at http://mcb.asm.org/.
Present address: Department of Medical Oncology, University Medical Center (UMC Utrecht), Utrecht, The Netherlands.
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