The cytoskeletal protein Zyxin inhibits Shh signaling during the CNS patterning in Xenopus laevis through interaction with the transcription factor Gli1

Abstract

Zyxin is a cytoskeletal protein that controls cell movements by regulating actin filaments assembly, but it can also modulate gene expression owing to its interactions with the proteins involved in signaling cascades. Therefore, identification of proteins that interact with Zyxin in embryonic cells is a promising way to unravel mechanisms responsible for coupling of two major components of embryogenesis: morphogenetic movements and cell differentiation. Now we show that in Xenopus laevis embryos Zyxin can bind to and suppress activity of the primary effector of Sonic hedgehog (Shh) signaling cascade, the transcription factor Gli1. By using loss- and gain-of-function approaches, we demonstrate that Zyxin is essential for reduction of Shh signaling within the dorsal part of the neural tube of X. laevis embryo. Thus, our finding discloses a novel function of Zyxin in fine tuning of the central neural system patterning which is based on the ventral-to-dorsal gradient of Shh signaling.

Cytoskeletal Protein Zyxin Inhibits the Activity of Genes Responsible for Embryonic Stem Cell Status

“…To identify genes directly or indirectly regulated by zyxin, we compared the next-generation sequencing (NGS) transcriptomes of X. laevis embryo neural plates excised together with the underlying mesoderm from wild-type embryos at the midneurula stage and from sibling embryos in which zyxin was downregulated with the anti-sense morpholino (MO) to zyxin mRNA as described in our previous paper (Martynova et al, 2013;Figure 1A). As a result,~200 differentially expressed genes were revealed (with R2-fold difference) (Table S1).…”

“…We next attempted to unravel the mechanism by which zyxin controls the stability of pou5f3.3 mRNA based on data from a previous study in which we performed yeast two-hybrid screening (2HS) to find proteins that could interact with zyxin in X. laevis embryos (Martynova et al, 2013). One of the potential protein partners of zyxin was Ybx1, a Y-box transcription factor that can form a ribonucleoprotein (RNP) complex with mRNA, thereby greatly increasing its resistance to degradation (Sommerville and Ladomery, 1996;Evdokimova et al, 2001).…”

“…Strikingly, we found that zyxin did not regulate the transcription of pou5f3 but rather provoked degradation of its mRNA. While attempting to reveal the mechanism by which zyxin regulated the stability of pou5f3 mRNA, we considered our previous finding that zyxin could physically interact with Ybx1, a Y-box factor, that is known to protect mRNA from degradation through its chaperone activity (Evdokimova et al, 2001;Martynova et al, 2013). Y-box (YB) proteins are DNA/RNA-binding proteins that belong to a large family of proteins with an evolutionarily conserved cold-shock domain.…”

Bioinformatic screening of genes present only in well regenerating vertebrates reveals novel FGF and purinergic signaling modulator - c-Answer

“…Lysates of embryos were prepared as described (Bayramov et al, 2011;Martynova et al, 2013). For immunoprecipitation, aliquots of lysates containing standard amount of tagged protein were mixed with EZview Red ANTI-MycAffinity Gel (Sigma E6654) or EZview Red ANTI-Flag Affinity Gel (Sigma F 2426) and incubated with rotation overnight at4C.…”

Mechano‐sensitive regulation of gene expression during the embryonic development

“…Recently we identified the Xenopus homologue of Zyxin and demonstrated that this protein can bind to the transcription factors Xanf1 and Gli1 and modulate their activity in cells of the CNS (Martynova et al, ). Given these data, we hypothesize that Zyxin may act as a mechanosensitive regulator of gene expression in early CNS development.…”