Tip-1 induces filopodia growth and is important for gastrulation movements during zebrafish development

• Published in: Development, growth & differentiation Vol. 49; no. 3; pp. 205 - 214
• Main Authors: Besser, Jaya, Leito, Jelani T.D, van der Meer, David L.M, Bagowski, Christoph P
• Format: Journal Article
• Language: English
• Published: Melbourne, Australia Melbourne, Australia : Blackwell Publishing Asia 01.04.2007; Blackwell Publishing Asia
• Subjects: Amino Acid Sequence; Animals; Cloning, Molecular; Danio rerio; development; Embryo, Nonmammalian - chemistry; Embryo, Nonmammalian - metabolism; filopodia; Gastrula - physiology; Green Fluorescent Proteins - analysis; Green Fluorescent Proteins - genetics; Homeodomain Proteins - antagonists & inhibitors; Homeodomain Proteins - genetics; Homeodomain Proteins - physiology; Molecular Sequence Data; Pseudopodia - genetics; Pseudopodia - physiology; Recombinant Fusion Proteins - analysis; Recombinant Fusion Proteins - genetics; RNA, Messenger - analysis; RNA, Messenger - metabolism; Tip-1; Wnt signaling; zebrafish; Zebrafish - embryology; Zebrafish - genetics; Zebrafish Proteins - antagonists & inhibitors; Zebrafish Proteins - genetics; Zebrafish Proteins - physiology
• ISSN: 0012-1592; 1440-169X
• DOI: 10.1111/j.1440-169X.2007.00921.x

Wnt signaling is essential during animal development and also plays important roles in pathological conditions. Two mayor pathways have been described: the β-catenin-dependent canonical (or classical) pathway and the β-catenin-independent non-canonical Wnt pathway. Recent binding studies suggest links between the small PDZ protein TIP-1 (Tax-1 interacting protein) to components of both Wnt pathways. We have cloned and characterized the zebrafish tip-1 gene. Whole mount in situ hybridization and semiquantitative reverse transcriptase-polymerase chain reaction (RT-PCR) indicated that zebrafish tip-1 is present as a maternal RNA and is ubiquitously expressed during early development. After 24 h of development, tip-1 expression was high in the central nervous system (CNS) whereas only weak expression was detected in the caudal regions of the zebrafish embryo. Tip-1 knockdown using antisense morpholino oligonucleotides, as well as ectopic tip-1 expression, led to elongation defects in zebrafish embryos and larvae. Both knockdown and overexpression of tip-1 resulted in a widened goosecoid (gsc) expression domain in shield stage embryos, led to an abbreviated prechordal plate, and to reduced convergent extension movements during gastrulation. We constructed a green fluorescence protein (GFP)/TIP-1 fusion protein which, when expressed in cultured fibroblasts (ZF4-cells), induced filopodia growth. Our observations indicate a role for TIP-1 in gastrulation movements and in filopodia growth induction.