Sprouty2-Mediated Inhibition of Fibroblast Growth Factor Signaling Is Modulated by the Protein Kinase DYRK1A

Abstract

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.

Advances in early kidney specification, development and patterning

“…Similarly, deletion of the receptor tyrosine kinase Met, the ligand of which is hepatocyte growth factor (HGF), also restricted branching morphogenesis, kidney size and nephron number (Ishibe et al, 2009). These results also raise the possibility that inhibitors of Ret signaling can inhibit other tyrosine kinases important for branching morphogenesis; for example, the Sprouty1 protein is known to suppress Fgfr signaling (Aranda et al, 2008). This further increases the complexity of signaling in the ureteric bud epithelium and makes interpretations at the biochemical level difficult.…”

Inhibition of DYRK1A destabilizes EGFR and reduces EGFR-dependent glioblastoma growth

“…Dissociated cells were plated in the absence of the drug, and the number of secondary spheres formed was counted. ***P ≤ 0.001. dampens its inhibitory influence on FGF-induced MAPK activation (57). This phosphorylation could potentially regulate SPRY2 binding to regulatory proteins and help discriminate between the EGF and FGF signaling pathways, as described for other residues (58,59).…”

Sprouty2 Interacts with Protein Kinase Cδ and Disrupts Phosphorylation of Protein Kinase D1

“…Spry2 has been reported to interact with at least two other kinases, namely Tesk1 and DYRK1A (13,14). Although the interaction with these two kinases abrogated the capacity of Spry2 to inhibit ERK1/2 activation, the reverse was true with the Spry2-PKC␦ interaction, with Spry2 curtailing the contribution of PKC␦ to ERK1/2 phosphorylation.…”

“…To date, a number of interacting partners of Spry have been identified, including c-Cbl, Grb2, Tesk1, Raf1, PP2A, and DYRK1A (11)(12)(13)(14)(15); several of these interactions contribute to the function of Spry2 as an inhibitor of the Ras/ERK pathway. In addition to binding to other proteins, studies have shown that Spry2 can affect the signaling effect of certain proteins, such as protein kinase C ␦ (PKC␦).…”