The zebrafish dyrk1b gene is important for endoderm formation

Abstract

Nodal-signaling is required for specification of mesoderm, endoderm, establishing left-right asymmetry and craniofacial development. Wdr68 is a WD40-repeat domain-containing protein recently shown to be required for endothelin-1 (edn1) expression and subsequent lower jaw development. Previous reports detected the Wdr68 protein in multiprotein complexes containing mammalian members of the dual-specificity tyrosine-regulated kinase (dyrk) family. Here we describe the characterization of the zebrafish dyrk1b homolog. We report the detection of a physical interaction between Dyrk1b and Wdr68. We also found perturbations of Nodal signaling in dyrk1b antisense morpholino knockdown (dyrk1b-MO) animals. Specifically, we found reduced expression of lft1 and lft2 (lft1/2) during gastrulation and a near complete loss of the later asymmetric lft1/2 expression domains. Although wdr68-MO animals did not display lft1/2 expression defects during gastrulation, they displayed a near complete loss of the later asymmetric lft1/2 expression domains. While expression of ndr1 was not substantially effected during gastrulation, ndr2 expression was moderately reduced in dyrk1b-MO animals. Analysis of additional downstream components of the Nodal signaling pathway in dyrk1b-MO animals revealed modestly expanded expression of the dorsal axial mesoderm marker gsc while the pan-mesodermal marker bik was largely unaffected. The endodermal markers cas and sox17 were also moderately reduced in dyrk1b-MO animals. Notably, and similar to defects previously reported for wdr68 mutant animals, we also found reduced expression of the pharyngeal pouch marker edn1 in dyrk1b-MO animals. Taken together, these data reveal a role for dyrk1b in endoderm formation and craniofacial patterning in the zebrafish.

The Molecular Chaperone TRiC/CCT Binds to the Trp-Asp 40 (WD40) Repeat Protein WDR68 and Promotes Its Folding, Protein Kinase DYRK1A Binding, and Nuclear Accumulation

“…WDR68 is not an exception because it binds to multiple proteins, including DYRK1A (9, 12, 13), DYRK1B (14), MEKK1 (8), HIPK2 (8), CUL4-DDB1 (6), DIAP1 (13), Drosophila atypical cadherin Dachsous (55), and TRiC/CCT (this study). Our proteomic analysis also identified many more putative WDR68-binding proteins with a wide variety of biological functions.…”

“…Previously, we found that overexpression of DYRK1A induced nuclear translocation of WDR68 in a kinase activityindependent manner (9). WDR68 regulates gene expression (7,14,63), so the binding of overexpressed DYRK1A to WDR68 in the nucleus might interfere with normal gene expression. This could partly explain how overexpressed DYRK1A affects gene expression and induces the pleiotropic phenotypes observed in Down syndrome patients.…”

“…We and others previously identified DYRK1A and DYRK1B as major cellular WDR68 binding partners (9,(12)(13)(14). The human gene for DYRK1A has received considerable attention because DYRK1A is encoded on chromosome 21 in the Down syndrome critical region (15,16).…”

The adaptor protein DCAF7 mediates the interaction of the adenovirus E1A oncoprotein with the protein kinases DYRK1A and HIPK2

“…In the zebrafish Danio rerio , DCAF7 (official gene symbol wdr68 ) was identified as a gene essential for craniofacial development19. Downregulation of dyrk1b induced similar defects in endoderm formation as reported for wdr68 mutant animals, supporting a functional interaction of these proteins in zebrafish development20. The DCAF7 ortholog in Drosophila , CG14614 (official gene symbol wap , wings apart, also called riq , riquiqui), is essential for normal wing-vein patterning and development of the adult jump muscle21.…”

Emerging role of DYRK family protein kinases as regulators of protein stability in cell cycle control

“…37 Another strong indication that DYRK1A and DYRK1B are functionally linked with E3 ubiquitin ligases is the fact that both of them, as well as HIPK2 (but not DYRK2), have repeatedly been shown to interact with DDB1 and CUL4-associated factor 7 (DCAF7, also called WDR68 or Han11). [38][39][40][41] DCAFs are a family of more than 50 proteins that function as adaptor proteins of the CUL4-DDB1 ubiquitin ligases to mediate substrate specificity. 42 The specific function of DCAF7 as a receptor subunit of E3 ligase complexes is unknown, but one might speculate that it mediates the interaction either between the kinase and its substrate or between the kinase and but it is clear that in this case, DYRK1A and DYRK1B do not act as priming kinases for GSK3.…”