Trb3 Regulates LR Axis Formation in Zebrafish Embryos

Abstract

Tribless family proteins are pseudokinases that lack DFG (Asp-Phe-Gly) motif in the functional kinase domain, regulating Akt and BMP pathways, insulin metabolism, hypoxia, and ubiquitination. This report concerns expression patterns and functional roles of trb3 in zebrafish embryonic development. trb3 is evolutionarily well-conserved and located on zebrafish chromosome 11. Spatiotemporal expression studies show that trb3 transcripts are abundant throughout embryogenesis, but confined to mesendodermal cells during the late blastula phase. Over-expression of trb3 ventralizes the embryos while a knockdown of trb3 using morpholino alters positioning of the heart, liver, and pancreatic buds as well as gut looping. Furthermore, constitutive activation of TGF-β signaling with TARAM-A* (TGF-β-related type I receptor) significantly increases the level of trb3 transcripts during the late blastula phase. Over-expression of trb3 reduces the level of smurf1 transcripts, a member of TGF-β signaling. We thus propose that Trb3 governs left-right (LR) axis patterning as a component of TGF-β signaling in vertebrate embryonic development.

Sinup is essential for the integrity of centrosomes and mitotic spindles in zebrafish embryos

“…Sinup- specific translation-blocking antisense morpholino and five mismatched control morpholino oligonucleotides were obtained from GeneTools (Philomath, USA) as the sequences were described in Ro et al ( 2005 ). sinup-EGFP mRNAs were synthesized with linearized pCS2– sinup - EGFP using mMESSAGE kit (Ambion) and injected into wild-type embryos at the one- to two-cell stage as described in Anuppalle et al ( 2013a ). For in situ hybridization, probes for myoD (Weinberg et al 1996 ), pax2.1 (Krauss et al 1991 ), gsc (Stachel et al 1993 ), dlx3 (Akimenko et al 1994 ), hgg (Thisse et al 1994 ), and ntl (Schulte-Merker et al 1994 ) were synthesized as described in Lee and Rhee ( 2009 ).…”

“…The ubiquitin proteasome system critically regulates various mechanisms such as cell polarity and neurogenesis (Anuppalle et al 2013a , 2013b ). Siah as E3 ligase modulates embryonic patterning (Kang et al 2014 ) and its interacting partner Sinup is involved in the neural plate formation (Ro et al 2005 ).…”