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P.n. Adler - One of the best experts on this subject based on the ideXlab platform.
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A single Frizzled Protein has a dual function in tissue polarity
Development (Cambridge England), 1994Co-Authors: Randi E. Krasnow, P.n. AdlerAbstract:The Drosophila Frizzled (fz) gene is required for the development of normal tissue polarity in the epidermis. Genetic epistasis experiments argue that fz is at the top of a regulatory hierarchy that controls the subcellular site for prehair initiation within the cells of the pupal wing (Wong and Adler, 1993; J. Cell Biol. 123, 209–221). Genetic mosaic experiments indicate that fz has both cell autonomous and cell non-autonomous functions that are separately mutable (Vinson and Adler, 1987; Nature 329, 549–551). Two species of fz mRNA have been identified, raising the question as to whether the two functions are provided by a single Protein or by two separate Protein species. We generated transgenic flies that express each of these mRNAs under the control of an hsp70 promoter. Only one of the transgenes (hsfzI) showed any fz activity. At 29 degrees C, the hsfzI transgene provided almost complete rescue of a null fz mutation, indicating that the Protein encoded by this cDNA can fulfill both fz functions. Overexpression of the hsfzI transgene resulted in two distinct tissue polarity phenotypes depending on the time of heat shock.
Yamei Jin - One of the best experts on this subject based on the ideXlab platform.
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Functional analysis of the Frzb2 gene in Schistosoma japonicum
Veterinary Research, 2019Co-Authors: Guifeng Cheng, Fanglin Qin, Yuanyuan Zhang, Jinming Liu, Yamei JinAbstract:AbstractSchistosomiasis is a globally important helminthic disease of humans and animals, and it is the second most common parasitic disease after malaria. Eggs produced by mature females are responsible for the disease’s occurrence and spread. Frzb2, a secreted Frizzled-related Protein, can inhibit Wnt signalling by competitive binding to the specific Frizzled Protein receptor. In this study, the complete gene sequence of SjFrzb2 was obtained by using 3′-rapid amplification of cDNA ends technology. SjFrzb2 transcript levels at different stages of S. japonicum maturation were evaluated by quantitative real-time RT-PCR analysis. SjFrzb2 was expressed at all developmental stages examined and exhibited the highest transcription level in 7-day-old worms, then gradually decreased during the growth and developmental stages to reach the lowest level at 18 days post-infection. SjFrzb2 gene expression was higher in female worms than in male worms and was significantly higher in female worms from a single-sex infection than in female worms from a bisexual infection. The functions of SjFrzb2 were explored via a small interfering RNA-based gene silencing approach and the soaking method. The results showed that SjFrzb2 gene knockdown impaired the growth and development of S. japonicum in mice, affecting not only the survival and morphological structure of the worms but also their reproductive ability and the viability of the produced eggs. Collectively, these observations imply that Frzb2 may be a novel target for the development of immuno- and/or small molecule-based therapeutics to control schistosomiasis fecundity and transmission.
Jeremy Nathans - One of the best experts on this subject based on the ideXlab platform.
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a member of the Frizzled Protein family mediating axis induction by wnt 5a
Science, 1997Co-Authors: Jeremy Nathans, Yanshu Wang, Igor B. Dawid, Xi He, Jean Pierre Saintjeannet, Harold E VarmusAbstract:In Xenopus laevis embryos, the Wingless/Wnt-1 subclass of Wnt molecules induces axis duplication, whereas the Wnt-5A subclass does not. This difference could be explained by distinct signal transduction pathways or by a lack of one or more Wnt-5A receptors during axis formation. Wnt-5A induced axis duplication and an ectopic Spemann organizer in the presence of hFz5, a member of the Frizzled family of seven-transmembrane receptors. Wnt-5A/hFz5 signaling was antagonized by glycogen synthase kinase-3 and by the amino-terminal ectodomain of hFz5. These results identify hFz5 as a receptor for Wnt-5A.
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a large family of putative transmembrane receptors homologous to the product of the drosophila tissue polarity gene Frizzled
Journal of Biological Chemistry, 1996Co-Authors: Yanshu Wang, Jennifer P Macke, Benjamin S Abella, Katrin Andreasson, Paul F Worley, Debra J Gilbert, Neal G Copeland, Nancy A Jenkins, Jeremy NathansAbstract:Abstract In Drosophila melanogaster, the Frizzled gene plays an essential role in the development of tissue polarity as assessed by the orientation of cuticular structures. Through a combination of random cDNA sequencing, degenerate polymerase chain reaction amplification, and low stringency hybridization we have identified six novel Frizzled homologues from mammals, at least 11 from zebrafish, several from chicken and sea urchin, and one from Caenorhabditis elegans. The complete deduced amino acid sequences of the mammalian and nematode homologues share with the Drosophila Frizzled Protein a conserved amino-terminal cysteine-rich domain and seven putative transmembrane segments. Each of the mammalian homologues is expressed in a distinctive set of tissues in the adult, and at least three are expressed during embryogenesis. As hypothesized for the Drosophila Frizzled Protein, the Frizzled homologues are likely to act as transmembrane receptors for as yet unidentified ligands. These observations predict the existence of a family of signal transduction pathways that are homologous to the pathway that determines tissue polarity in Drosophila.
Stephen C Ekker - One of the best experts on this subject based on the ideXlab platform.
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xenopus Frizzled 7 morphant displays defects in dorsoventral patterning and convergent extension movements during gastrulation
Genesis, 2001Co-Authors: Saulius Sumanas, Stephen C EkkerAbstract:Wnt signaling has been implicated in the process of gastrulation in Xenopus laevis. Overexpression of Wnt molecules, such as a putative dominant-negative form of Wnt8 (Hoppler et al., 1996), Wnt11 (Tada and Smith, 2000), as well as wild type Wnt5A and Wnt11 Proteins (Du et al., 1995; Gradl et al., 1999; Moon et al., 1993) interferes with convergent extension movements during gastrulation. Overexpression of some other Wnt signaling pathway members such as full-length and truncated forms of Xenopus Frizzled-7 (Djiane et al., 2000; Sumanas et al., 2000), a truncated form of Xenopus disheveled (Sokol, 1996) also causes similar defects. However, evidence for the requirement of a specific Wnt pathway Protein in the gastrulation process is still missing. Here we investigated the function of Xenopus Frizzled-7 (Xfz7) utilizing the morpholino phosphorodiamidate antisense oligonucleotides approach (Heasman et al., 2000; Summerton, 1999). A mixture of two morpholinos designed against two different orthologous copies of Xfz7 was injected into unfertilized oocytes. The resulting embryos (Xfz7 morphants) failed to properly close the blastopore, whereas the more severely affected embryos exogastrulated. The gastrulation defect was caused by inhibition of convergent extension movements as demonstrated by an animal cap cell motility assay (Smith et al., 1990). Adding synthetic Xfz7 RNA alleviated the observed gastrulation defect arguing for the specificity of the morpholino-based targeting. At tadpole stages, Xfz7 morphants displayed loss or reduction of anterior structures. Molecular analysis showed that approximately half of Xfz7 morphants had reduced expression of a dorsal marker Xnr3 at the gastrula stage. Xnr3 is known to be the direct target of the maternal Wnt axis induction pathway (Smith et al., 1995; McKendry et al., 1997) and has previously been shown to be under maternal Xfz7 control (Sumanas et al., 2000). The results presented here argue for two different Xfz7 functions. They confirm our previous findings that Xfz7 is required for the dorsoventral Wnt/b-catenin axis induction pathway (Sumanas et al., 2000) and demonstrate a Xfz7 requirement in a zygotic Wnt pathway that regulates morphogenetic movements during gastrulation. This is the first evidence for a vertebrate Frizzled Protein to act in two distinct Wnt-signaling pathways, as known to be the case for Drosophila Frizzled-1 (Adler, 1992; Bhanot et al., 1999; Chen and Struhl, 1999). To study Xfz7 function during development, we designed two different morpholinos against the 5’UTR of two distinct orthologous copies of the Xfz7 gene present due to the allotetraploid nature of Xenopus (Kobel and Du Pasquier, 1986). One ortholog has been reported by Djiane et al. (2000)., Medina et al. (2000), and Sumanas et al. (2000), and the other ortholog of Xfz7 was reported by Wheeler and Hoppler (1999). These two Xfz7 orthologs are 97% identical in amino acid sequences, but contain more significant differences in the UTR sequences (data not shown). Both orthologs have similar expression patterns at all stages reported. A mixture of the two different morpholinos (MO-1 and MO-2) was injected into unfertilized oocytes, and the oocytes were subsequently fertilized using the host–transfer method (Heasman et al., 1994). Injection of individual morpholinos up to 20 ng resulted in no significant developmental defects, whether delivered into early embryos or into oocytes followed by host transfer fertilization (data not shown). We used doses of 5 ng (2.5ng each MO) and 10 ng (5ng each MO) of the morpholino mixture to simultaneously knockdown both orthologous copies of Xfz7. Xfz7 morphants developed seemingly normally with only a slight developmental delay until the start of gastrulation. During gastrulation, Xfz7 morphants formed greatly enlarged blastopores, which subsequently failed to involute properly, resulting in exogastrulating embryos at higher doses of morpholino used (Fig. 1a–c, i). Microinjecting synthetic Xfz7 RNA into oocytes significantly reduced the severity of the phenotype, resulting in a greater percentage of normal and weakly affected embryos (Fig. 1d, i). At tailbud and tadpole stages, Xfz7 morphants displayed defects in dorsoanterior structures. They commonly had a reduced or missing head and cement gland
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Zebrafish Frizzled-2 morphant displays defects in body axis elongation.
genesis, 2001Co-Authors: Saulius Sumanas, Hyon Kim, Spencer Hermanson, Stephen C EkkerAbstract:Wnt signaling has been implicated in many patterning processes in a vertebrate embryo including morphogenetic cell rearrangements during gastrulation. Pipetail (wnt5) and silberblick (wnt11) zebrafish mutants undergo abnormal gastrulation with an undulated notochord ( pipetail) and cyclopic embryos ( silberblick) at later stages of development (Hammerschmidt et al., 1996; Heisenberg et al., 1996; Heisenberg et al., 2000; Rauch et al., 1997). Wnt Proteins are known to transmit signals via the Frizzled seven-pass transmembrane receptor family (Bhanot et al., 1996). We have isolated cDNA encoding a new Frizzled family Protein, zebrafish Frizzled-2 (Fz2). Zebrafish Frizzled-2 is a likely ortholog of human Frizzled-2 by the sequence homology alignments and mapping data analysis. Fz2 is expressed zygotically within the notochord, somitic and posterior paraxial mesoderm. For Protein knockdown studies, we utilized morpholino phosphorodiamidate antisense oligonucleotides (morpholinos, MOs). Injection of two different morpholinos into early zebrafish embryos targeted to fz2 caused similar developmental defects. Fz2-morpholino injected embryos (morphants) are shorter than controls and display an undulating or kinked notochord, neural tube, and hypochord. Similar, although weaker, undulations of axial structures have been observed in pipetail mutant embryos, raising possibility that fz2 may function as a receptor in the wnt5 pathway regulating gastrulation movements. We isolated a novel zebrafish Frizzled homolog from gastrula stage cDNA library by the polymerase chain reaction (PCR). The isolated gene encodes a putative Frizzled Protein with highest homology to the Frizzled-2 subfamily as evident from BLAST and CLUSTAL alignments (Fig. 1a, b). Radiation hybrid mapping using panel LN54 (Hukriede et al., 1999) places fz2 on linkage group 3, linked to the marker Z22516 (distance 0.00cR, LOD score 22.2). To confirm that we isolated true Frizzled-2 ortholog from zebrafish, we performed synteny analysis between corresponding zebrafish and human chromosome regions. Zebrafish fz2 maps to the marker Z22516, which is located between the hoxb9a and dlx8 genes on linkage group 3 in the LN54 panel (Hukriede et al., 1999; marker list at http://zfin.org/ZFIN/). This region of zebrafish linkage group 3 is syntenic to the human chromosome 17 region. Human fz2 maps by FISH to 17q21.1 (Zhao et al., 1995), human hoxB9 maps to 17q21-q22 (Acampora et al., 1989; Apiou et al., 1996; HUGO database), and human Dlx4, an ortholog of zebrafish Dlx8, maps to 17q21.33 (Nakamura et al., 1996; Stock et al., 1996). Thus, human Frizzled-2 is likely to be the true ortholog of the zebrafish Frizzled-2 gene. Using Northern blotting, we detected a single, zygotically expressed transcript of fz2, with maximal expression level approximately at the five-somite stage (Fig. 1c). In situ hybridization revealed weak and ubiquitous expression starting from the shield stage (data not shown). During early somitogenesis, fz2 RNA is detected within the forming somites as well as in two longitudinal stripes within the paraxial posterior mesoderm (Fig. 1, d–g). There is also weak expression within notochordal cells anterior to fz2 expression in the forming somites. At the 20-somite stage, fz2 expression is detected in the posterior part of the notochord and in the posterior somitic mesoderm (Fig. 1h, i). At 26 hpf, fz2 is localized within the tailbud mesoderm (Fig. 1k). Injecting 100–500 pg fz2 RNA into fish embryos at the 1–2 cell stage caused severe hyperdorsalization in .90% of experimental embryos (data not shown), as noted previously for other Frizzled Proteins (Nasevicius et al., 1998). A number of fz2-overexpressing embryos displayed secondary axes (data not shown). This illustrates that fz2 is capable of activating dorsoventral axis induction pathway when overexpressed in zebrafish embryos. To study fz2 function, we utilized an antisense morpholino oligonucleotide approach (Nasevicius and Ekker, 2000; Summerton, 1999). Two nonoverlapping morpholinos were designed against the fz2 sequence. Injecting either morpholino against fz2 produced similar phenotypes, indicating a likely high specificity of targeting to fz2 transcripts. The resulting embryos (fz2 morphants) display characteristic defects not commonly seen with other unrelated morpholinos. At 70% epiboly, fz2 morphants have an oblong shape compared with
Charles A. Ettensohn - One of the best experts on this subject based on the ideXlab platform.
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Cloning and developmental expression of a novel, secreted Frizzled-related Protein from the sea urchin, Strongylocentrotus purpuratus.
Mechanisms of development, 2002Co-Authors: Michele R. Illies, Margaret T. Peeler, Anna M. Dechtiaruk, Charles A. EttensohnAbstract:Wnt Proteins and their receptors, members of the Frizzled Protein family, play a key role in regulating a wide range of developmental processes. Recently, putative regulators of Wnt signaling known as secreted Frizzled-related Proteins (SFRPs) have been identified in several vertebrates. Here, we describe the cloning of a novel SFRP (suSFRP1) from the sea urchin, Strongylocentrotus purpuratus. SuSFRP1 contains a putative signal sequence, four cysteine-rich domains and a single Ig domain. The developmental expression of suSFRP1 mRNA is highly dynamic and can be separated into three phases: (1) abrupt accumulation in most or all cells of the embryo at the early blastula stage; (2) restriction of expression to the prospective endoderm and animal pole region of the gastrula; and (3) expression in prospective muscle cells of the coelomic pouches during late embryogenesis.
