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A transcriptional corepressor, Xenopus furry (Xfurry), is expressed in the chordamesodermal region and induces secondary dorsal axes when overexpressed on the ventral side of the embryo. The N-terminal furry domain functions as a repressor, and the C-terminal leucine zipper (LZ) motifs /coiled-coil structure, found only in vertebrate homologs, contributes to the nuclear localization. The engrailed repressor (enR)+LZ repressor construct, which has properties similar to Xfurry, induced several chordamesodermal genes. In contrast, an antisense morpholino oligonucleotide, Xfurry-MO, and the activating construct, herpes simplex virus protein (VP16)+LZ, had effects opposite those of Xfurry overexpression. Because blocking protein synthesis with cycloheximide superinduced several Xfurry transcriptional targets, and because expression of enR+LZ induced such genes under cycloheximide treatment, we analyzed the role of an Xfurry transcriptional target, microRNA miR-15. Cycloheximide reduced the expression of primary miR-15 (pri-miR-15), whereas miR-15 reduced the expression of genes superinduced by cycloheximide treatment. These results show that Xfurry regulates chordamesodermal genes by contributing to repression of pretranscriptional gene silencing by miR-15.
Fig. 1. Characterization of Xfurry. (A) Temporal expression of Xfurry detected by RT-PCR. Numbers indicate developmental stages. U, unfertilized eggs. (B) Regional RT-PCR of Xfurry at stage 10. (CâF) Whole-mount in situ hybridization. (C) Arrowhead indicates the dorsal lip (stage 10). (D) Arrowhead indicates the chordamesodermal region (stage 12). (E and F) Strong expression in the notochord was maintained through stage 25 (E) and stage 33 (F). (G) Control embryo (stage 33). (H) Xfurry (2 ng/blastomere) injected into ventral blastomeres of the four-cell embryo induced a secondary axis without anterior structures (arrowhead) in 63% of embryos (n = 60). (I) Expression of the chordamesodermal genes was induced in animal caps (stage 10) that were dissected from embryos injected with Xfurry (2 ng/blastomere). Gsc, goosecoid; Pint, pintallavis; Chd, chordin; ODC, Ornithine decarboxylase. (J) Control embryo (stage 26). (K) Injection of Xfurry-MO (5 ng/blastomere) into dorsal blastomeres of four-cell embryos shortened the dorsal axis in all embryos (n = 58). (L) Expression of chordamesodermal marker genes was reduced in Xfurry-MOâinjected embryos, but transcripts of Xfurry were increased by Xfurry-MO (stage 10).
Fig. 2. Function of Xfurry as a transcriptional corepressor. (A) Fluorescent signals of Xfurry constructs in stage-10 mesodermal cells (Fig. S5). Red signals indicate cell nuclei stained with DAPI. (Top Row) Xfurry+GFP. (Second Row) FD+LZ+GFP construct. (Third Row) LZ+GFP. (Bottom Row) FD+GFP. Arrowheads show colocalization of GFP and DAPI signals. Arrows indicate noncolocalized signals. (B) Control embryo (stage 27). (C) Dorsal injection of FD+SiaHD interfered with head development. (D) Expression of FD+SiaHD reduced transcripts of goosecoid (Gsc) and Cerberus (Cer). (EâG) Phenotypes of injected stage-29 embryos. (E) Control embryo. (F) Ventral injection of enR+LZ (400 pg/blastomere) induced secondary axes in all embryos (n = 59). (G) Dorsal injection of VP16+LZ (400 pg/blastomere) shortened the dorsal axis in all embryos (n = 60). (H) Dorsal expression of enR+LZ induced chordamesodermal and headorganizer genes, and expression of VP16+LZ reduced those genes (stage 10).
Fig. 3. Target genes of Xfurry and their superinduction. (A) Early inducers β-catenin, VegT, and Xnr5 induced transcripts of Xfurry (stage 10). (B) enR+LZ induced chordamesodermal genes in the pre-MBT cycloheximide-treated animal caps, and VP16+LZ reduced or did not alter expression of those genes (stage 10). (C) Superinduction in the animal caps treated with both cycloheximide (CHX) (Left) and anisomycin (ANI) (Right) (stage 10). (D) Injection of pintallavis-MO induced expression of pintallavis (stage 10). (E) Injection of goosecoid-MO induced expression of goosecoid (stage 10). (F) Injection of both pintallavis-MO and goosecoid-MO induced expression of Xfurry (stage 10).
Fig. 4. The role of small RNAs in gene expression. (AâD) Phenotypes of small RNA-injected embryos (stage 30). (A) Control embryo. (BâD) Small RNAs in the range of 20â60 (B), 60â100 (C), and 100â120 (D) bases were injected into dorsal blastomeres of four-cell embryos. (C) Injection of small RNAs (60â100 bases) shortened the dorsal axis in all embryos (n = 56). (E) Injection of small RNAs (60â100 bases) into all blastomeres of four-cell embryos markedly reduced the expression of chordamesodermal genes but increased expression of Xfurry (stage 10). (F) Injection of small RNAs (60â100 bases) into four animal blastomeres of 32-cell embryos in solution containing cycloheximide decreased expression of chordamesodermal genes in the animal caps and slightly reduced the expression of Xfurry (stage 10). (G) Expression of enR+LZ reduced pri-mir-15, and expression of VP16+LZ slightly up-regulated pri-mir-15 in the cycloheximide-treated animal caps (stage 10). (H) Overexpression of mir-15 in the cycloheximide-treated animal caps reduced expression of chordamesodermal genes and did not alter expression of Xfurry. (I) Cycloheximide treatment from stage 7 reduced expression of pri-mir-15 in the treated animal caps (stage 10). (J) Injection of pintallavis-MO (Pint-MO) into all blastomeres of four-cell embryos increased expression of goosecoid and Xnot, did not alter the expression of chordin, and reduced the expression of pri-mir-15 (stage 10). (K) Model of the proposed Xfurry signaling pathway. Xfurry represses expression of mir-15 and microRNAs. Several chordamesodermal genes are repressed by mir-15 and microRNAs. Xfurry also is induced by goosecoid as a downstream gene. Then this feedback loop signaling pathway together with Xfurry regulates expression of chordamesodermal genes. Moreover, low protein levels of several genes activate a system that senses the low-protein condition, thereby inducing Xfurry expression and activating the function of Xfurry as a corepressor. Pin, pintallavis.
Fig. S2. Dorsal overexpression of Xfurry. (A) Control (stage 28). (B) Injection of Xfurry (2 ng/blastomere) into dorsal blastomeres of four-cell embryos had no effect on axis formation (n = 60).
Fig. S3. Confirmation of the morpholino specificity. A tracer, Alexa 594-dextran (300 pg), GFP constructs, and morpholinos were injected in the animal pole of four-cell embryos and were observed at stage 10 to show the injected embryos (Top Row), the fluorescent Alexa 594-dextran tracer (Middle Row), and GFP fluorescence (Bottom Row). Xfurry-MO specifically reduced translation of sequences containing Xfurry-GFP targeted with Xfurry-MO at the 5â²-region but did not reduce translation of 5-mis-Xfurry-GFP, which has no targeted sequence.
Fig. S4. Rescue experiments among Xfurry, Xfurry-MO, enR+LZ, and VP16+LZ. (A) Control (stage 33). (B) Injection of Xfurry-MO (5 ng/blastomere) into dorsal blastomeres of four-cell embryos interfered with head formation and shortened the axis of all embryos, as shown also in Fig. 1K (n = 40). (C) The cement gland was rescued, and the axis was slightly elongated by coinjection of Xfurry (2 ng/blastomere) and Xfurry-MO (5 ng/blastomere) into dorsal blastomeres of fourcell embryos (57.9%; n = 57). (D) Dorsal expression of enR+LZ (400 pg/blastomere) also rescued the phenotype of Xfurry-MOnjected embryos (78.6%; n = 56). (E) Dorsal injection of VP16+LZ (400 pg/blastomere) interfered with head formation and shortened the axis of all embryos, as in Fig. 2G (n = 40). (F) Dorsal expression of Xfurry (2 ng/blastomere) rescued the phenotype of VP16+LZ-injected embryos (52.5%, n = 59).
Fig. S7. Overexpression of nuclear DBF2-related 1 (NDR1) and NDR2. (A) Control (stage 33). (B) Overexpression of NDR1 (1 ng/blastomere) into ventral blastomeres of four-cell embryos had no effect on axis formation (n = 60). (C) Ventral overexpression of NDR2 (1 ng/blastomere) at the four-cell embryo stage also had no effect on axis formation (n = 60).
fry (FRYmicrotubule binding protein) gene expression in Xenopus laevis embryos, NF stage 10, as assayed by in situ hybridization, vegetal view, dorsal up.
fry (FRYmicrotubule binding protein ) gene expression in bisected Xenopus laevis embryo, mid-sagittal section, assayed via in situ hybridization, NF stage 12, dorsal left, animal pole up.
Chiba,
MST2- and Furry-mediated activation of NDR1 kinase is critical for precise alignment of mitotic chromosomes.
2009, Pubmed
Chiba,
MST2- and Furry-mediated activation of NDR1 kinase is critical for precise alignment of mitotic chromosomes.
2009,
Pubmed Cho,
Molecular nature of Spemann's organizer: the role of the Xenopus homeobox gene goosecoid.
1991,
Pubmed
,
Xenbase Cong,
The furry gene of Drosophila is important for maintaining the integrity of cellular extensions during morphogenesis.
2001,
Pubmed Danilov,
Negative autoregulation of the organizer-specific homeobox gene goosecoid.
1998,
Pubmed
,
Xenbase Dawid,
Regulatory interactions during embryogenesis in Xenopus laevis.
1993,
Pubmed
,
Xenbase Emoto,
Control of dendritic branching and tiling by the Tricornered-kinase/Furry signaling pathway in Drosophila sensory neurons.
2004,
Pubmed Fan,
A role for Siamois in Spemann organizer formation.
1997,
Pubmed
,
Xenbase Fukui,
SDF-1 alpha regulates mesendodermal cell migration during frog gastrulation.
2007,
Pubmed
,
Xenbase Geng,
The tricornered gene, which is required for the integrity of epidermal cell extensions, encodes the Drosophila nuclear DBF2-related kinase.
2000,
Pubmed Harland,
In situ hybridization: an improved whole-mount method for Xenopus embryos.
1991,
Pubmed
,
Xenbase Hawkins,
Promoter targeted small RNAs induce long-term transcriptional gene silencing in human cells.
2009,
Pubmed Hayette,
AF4p12, a human homologue to the furry gene of Drosophila, as a novel MLL fusion partner.
2005,
Pubmed He,
The tricornered Ser/Thr protein kinase is regulated by phosphorylation and interacts with furry during Drosophila wing hair development.
2005,
Pubmed Heasman,
Overexpression of cadherins and underexpression of beta-catenin inhibit dorsal mesoderm induction in early Xenopus embryos.
1994,
Pubmed
,
Xenbase Hirata,
Fission yeast Mor2/Cps12, a protein similar to Drosophila Furry, is essential for cell morphogenesis and its mutation induces Wee1-dependent G(2) delay.
2002,
Pubmed Jing,
Involvement of microRNA in AU-rich element-mediated mRNA instability.
2005,
Pubmed Kessler,
Siamois is required for formation of Spemann's organizer.
1997,
Pubmed
,
Xenbase Kim,
MicroRNA-directed transcriptional gene silencing in mammalian cells.
2008,
Pubmed Lemaire,
Expression cloning of Siamois, a Xenopus homeobox gene expressed in dorsal-vegetal cells of blastulae and able to induce a complete secondary axis.
1995,
Pubmed
,
Xenbase Lund,
Deadenylation of maternal mRNAs mediated by miR-427 in Xenopus laevis embryos.
2009,
Pubmed
,
Xenbase Lustig,
A Xenopus nodal-related gene that acts in synergy with noggin to induce complete secondary axis and notochord formation.
1996,
Pubmed
,
Xenbase Martello,
MicroRNA control of Nodal signalling.
2007,
Pubmed
,
Xenbase Martynova,
Patterning the forebrain: FoxA4a/Pintallavis and Xvent2 determine the posterior limit of Xanf1 expression in the neural plate.
2004,
Pubmed
,
Xenbase Morris,
RNA-directed transcriptional gene silencing and activation in human cells.
2009,
Pubmed Morris,
Small interfering RNA-induced transcriptional gene silencing in human cells.
2004,
Pubmed Nelson,
RAM: a conserved signaling network that regulates Ace2p transcriptional activity and polarized morphogenesis.
2003,
Pubmed Onuma,
Multiple nodal-related genes act coordinately in Xenopus embryogenesis.
2002,
Pubmed
,
Xenbase Piccolo,
The head inducer Cerberus is a multifunctional antagonist of Nodal, BMP and Wnt signals.
1999,
Pubmed
,
Xenbase Rosa,
The miR-430/427/302 family controls mesendodermal fate specification via species-specific target selection.
2009,
Pubmed
,
Xenbase Ruiz i Altaba,
Ectopic neural expression of a floor plate marker in frog embryos injected with the midline transcription factor Pintallavis.
1993,
Pubmed
,
Xenbase Sander,
The opposing homeobox genes Goosecoid and Vent1/2 self-regulate Xenopus patterning.
2007,
Pubmed
,
Xenbase Sasai,
Xenopus chordin: a novel dorsalizing factor activated by organizer-specific homeobox genes.
1994,
Pubmed
,
Xenbase Schohl,
A role for maternal beta-catenin in early mesoderm induction in Xenopus.
2003,
Pubmed
,
Xenbase Suzuki,
Transcriptional regulation by promoter targeted RNAs.
2009,
Pubmed Tadano,
Differential induction of regulatory genes during mesoderm formation in Xenopus laevis embryos.
1993,
Pubmed
,
Xenbase Takahashi,
Two novel nodal-related genes initiate early inductive events in Xenopus Nieuwkoop center.
2000,
Pubmed
,
Xenbase Valencia-Sanchez,
Control of translation and mRNA degradation by miRNAs and siRNAs.
2006,
Pubmed von Dassow,
Induction of the Xenopus organizer: expression and regulation of Xnot, a novel FGF and activin-regulated homeo box gene.
1993,
Pubmed
,
Xenbase Wylie,
Maternal beta-catenin establishes a 'dorsal signal' in early Xenopus embryos.
1996,
Pubmed
,
Xenbase Zhang,
The role of maternal VegT in establishing the primary germ layers in Xenopus embryos.
1998,
Pubmed
,
Xenbase