XB-ART-49703Development 2014 Sep 01;14118:3505-16. doi: 10.1242/dev.114033.
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The PDZ domain protein Mcc is a novel effector of non-canonical Wnt signaling during convergence and extension in zebrafish.
During vertebrate gastrulation, a complex set of mass cellular rearrangements shapes the embryonic body plan and appropriately positions the organ primordia. In zebrafish and Xenopus, convergence and extension (CE) movements simultaneously narrow the body axis mediolaterally and elongate it from head to tail. This process is governed by polarized cell behaviors that are coordinated by components of the non-canonical, β-catenin-independent Wnt signaling pathway, including Wnt5b and the transmembrane planar cell polarity (PCP) protein Vangl2. However, the intracellular events downstream of Wnt/PCP signals are not fully understood. Here, we show that zebrafish mutated in colorectal cancer (mcc), which encodes an evolutionarily conserved PDZ domain-containing putative tumor suppressor, is required for Wnt5b/Vangl2 signaling during gastrulation. Knockdown of mcc results in CE phenotypes similar to loss of vangl2 and wnt5b, whereas overexpression of mcc robustly rescues the depletion of wnt5b, vangl2 and the Wnt5b tyrosine kinase receptor ror2. Biochemical experiments establish a direct physical interaction between Mcc and the Vangl2 cytoplasmic tail. Lastly, CE defects in mcc morphants are suppressed by downstream activation of RhoA and JNK. Taken together, our results identify Mcc as a novel intracellular effector of non-canonical Wnt5b/Vangl2/Ror2 signaling during vertebrate gastrulation.
PubMed ID: 25183869
Article link: Development
Species referenced: Xenopus
Genes referenced: ctnnb1 gsc hhex mapk8 mcc rhoa ror2 sia1 tbxt tp53 vangl2 wnt11 wnt5b
Morpholinos: mcc MO1
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|Supplementary Figure 1. Later expression of zebrafish mcc and cloning and expression of Xenopus laevis Mcc. (A) Zebrafish mcc expression from 2 to 5 days post fertilization (dpf) by whole-mount in situ hybridization (WISH). mcc transcript levels in the somites decrease and then increase, but persist in head structures and also emerge in the developing digestive system and swim bladder. Section of 5 dpf embryo (far right panel); plane of section indicated by dashed line. Abbreviations: gt, gut tube; l, liver; p, pancreas; sw, swim bladder; nt, neural tube. ( B) Expression analysis of Xenopus laevis Mcc by QPCR. Mcc transcripts are detected both maternally (up to stage (St) 8) and zygotically (St 10 and beyond). (C) Xenopus Mcc expression from St 3 to 35 by WISH and vibratome sections of St 18 and 35 embryos at the indicated planes (white and black dashed lines). St 3 (4-cell stage), animal view; St 8, lateral view; St 10 and 11, vegetal view; St 23 and 24, lateral view. Abbreviations: nc, neural crest; ba, branchial arches; mn, motor neurons; nt, nephric tubules; s, somite; lm, lateral mesoderm.|
|Supplementary Figure 2. Supporting information for Figure 2. (A) Series of control mRNA and morpholino injections at 1 day post fertilization (dpf): p53 MO alone; mcc mismatch control morpholino (MO1*); co-injection of p53 MO and mcc MO1, which attenuates the anterior cell death sometimes observed with either mcc MO1 or MO2 (Fig. 2A); overexpression of nls-lacZ mRNA; and co-injection of mcc MO1 and nls-lacZ mRNA. Injection of the shorter mouse Mcc isoform 2 mRNA, like isoform 1 (Fig. 2A), efficiently rescues both mcc MO1 and MO2. (B) wnt11/slb and wnt11-related (wntllr) homozygous mutant embryos (Heisenberg et al., 2000; Matsui et al., 2005) at 10 hpf show characteristic convergence and extension defects: the polster (hgg1) lags behind the wider neural plate (dlx3) and the midline notochord (ntl1) is thickened. These phenotypes are seen in mcc MO1 or MO2-injected embryos and are rescued equally as efficiently by mouse Mcc isoform 2 mRNA as isoform 1 (Fig. 2A). Overexpression of zebrafish mcc results in similar CE defects as mcc MO1 or MO2 injection (Fig. 2A). Abbreviations: np, neural plate; p, polster; n, notochord. (C) Mcc loss of function in Xenopus leads to an increase of embryos with gastrulation and neural tube closure defects. Embryos were injected at the 2-cell stage with 10, 15, or 20 ng control or Mcc ATG MO. Gastrulation defects were analyzed at stage 11 (a-i) and neurulation defects (j-o) at stage 19. Vegetal (a,c,e,g) or lateral (b,d,f,h) views of gastrula stage embryos are shown. Neurula stage embryos are shown from a posterior view, the injected site is on the right (j-m). (a,b) Uninjected control embryo. (c,d) Embryo injected with 20 ng control MO (Co MO) showing normal gastrulation. (e-h) Embryos injected with 20 ng Mcc ATG MO showing defective blastopore closure (e,f) and exogastrulation (g,h). (i) Graph summarizing the percentage of gastrulation defects in three independent experiments. MO concentrations (10, 15 or 20) are in ng. Standard error of the mean and number of injected embryos are indicated for each column. The same embryos were analyzed for neural tube closure defects at stage 19 (j-m,o). (j) Embryo injected with 20 ng control MO shows normal neural tube closure. (k,l,m) Embryos injected with 20 ng Mcc ATG MO show defective neural tube closure on the injected site (right). (n) Transverse section through the neural tube of an embryo injected with 20 ng Mcc ATG MO together with lacZ RNA (blue staining, indicates the injected side; dashed line indicates the midline). Black arrow marks the hinge point and the rolled up neural tube of the control site. The blue arrow marks the hinge point area of the injected side. Note the distance between the blue arrow and the midline suggesting defects in cell intercalation on the injected site. Scale bar = 50 μm. (o) Graph summarizing the percentage of neural tube closure defects of the same embryos as shown in (i). (D) Mcc overexpression (2ng of EGFP-Mcc mRNA) in Xenopus results in foreshortening and buckling of the anteroposterior axis—two classic CE phenotypes (St 38). (E) Activation of the canonical, β-catenin-dependent Siamois luciferase reporter (Brannon et al., 1997) is not affected by Mcc overexpression in injected Xenopus embryos. See Materials and Methods for additional details about luciferase reporter constructs and DNA/mRNA concentrations. (F) Early gastrulation and germ layer specification are unperturbed in Xenopus Mcc morphants. Whole-mount in situ hybridization for Brachyury (Bra, pan-mesodermal), Gsc (dorsal organizer) and Hex (nascent endoderm) expression at St 10.5. Alternating animal pole and hemisected views are shown for each riboprobe with dorsal to the right. (G) Zebrafish embryos at 52 hpf. Wild-type (WT) uninjected, wnt11 MO injected, and co-injection of wnt11 MO with zebrafish mcc mRNA. wnt11 morphants typically have eyes that are too close together or fused (Heisenberg et al., 2000)—a phenotype that is not rescued upon mcc overexpression. (A-E) Morpholino and mRNA concentrations are provided in Supp. Table 3. Phenotypic distributions are indicated as percentages, with scored embryo counts listed in Supp. Table 4.|
|mcc (mutated in colorectal cancers) gene expression in Xenopus laevis embryo, assayed via in situ hybridization, NF stage 25, lateral view, anterior left, dorsal up.|
|mcc (mutated in colorectal cancers) gene expression in Xenopus laevis embryo, assayed via in situ hybridization, NF stage 35, lateral view, anterior left, dorsal up.|