Click here to close
Hello! We notice that you are using Internet Explorer, which is not supported by Xenbase and may cause the site to display incorrectly.
We suggest using a current version of Chrome,
FireFox, or Safari.
???displayArticle.abstract???
A hallmark of Alzheimer's, Huntington's and similar diseases is the assembly of proteins into amyloids rather than folding into their native state. There is an increasing appreciation that amyloids, under specific conditions, may be non-pathogenic. Here we show that amyloids form as a normal part of Xenopus oocyte development. Amyloids are detectable in the cytosol and the nucleus using an amyloid binding dye and antibodies that recognize amyloid structure. In the cytosol, yolk platelets are amyloid reactive, as are a number of yet to be characterized particles. In the nucleus, we find particles associated with transcription by RNA polymerase I, II and III and RNA processing contain amyloids. Nuclear amyloids remain intact for hours following isolation; however, RNase treatment rapidly disrupts nuclear amyloids.
???displayArticle.pubmedLink???
27215327
???displayArticle.pmcLink???PMC4920187 ???displayArticle.link???Biol Open ???displayArticle.grants???[+]
Fig. 1. Xenopus oocytes contain nuclear and spatially localized cytosolic amyloid particles. Sectioned ovary was probed for amyloids using thioflavin T (thio-T) or antibodies that recognize either oligomeric (A11) or fibrillar (OC) amyloid epitopes. (A-C) Thio-T staining in (A) highlights the difference in amyloid-positive yolk deposition as oocytes develop from stage II on (left) to stage VI (right). B and C show enlargements of the stage II (B) and stage VI (C) oocyte nuclear thio-T staining in A. Scale bars: (A) 500 µm and (B-C) 50 µm. (D,E) Antibody detection of amyloids in stage III oocytes using either an A11 (D) or OC (E) antibody reveals nuclear (dotted circles) and cytosolic staining of particles similar to that found in A-C, but with lower reactivity to yolk platelets. Arrowheads in D and E indicate increased staining in vegetal hemisphere of oocytes. (F) An isotype control antibody-stained sample. Insets in E and F depict increased exposure times to better visualize nuclear staining. Scale bars: 100 µm.
Fig. 2. Isolated Xenopus nuclei (GVs) can be used for combinatorial identification of nuclear particles with thioflavin T and particle specific antibodies. (A) Manual removal of a GV from a stage VI oocyte. Scale bar: 500 µm. (B) Isolated GVs demonstrate amyloid containing particles seconds after thio-T staining. Scale bar: 200 µm. (C) Overlay of nucleolin immunofluorescence (red, D) and thio-T (green, E) staining of an isolated GV. Scale bar: 100 µm. (F) Overlay of images (G, green) stained with thio-T and (H, red) coilin immunofluorescence. A pearl particle is circled with a solid line, a histone locus body circled with a dashed line. Scale bar: 5 µm. (I) Overlay of panels (J, green) stained with thio-T and (K, red) SC35 immunofluorescence. Dashed lines indicate some thio-T-positive SC35-negative particles, dotted lines indicate a thio-T- and SC35-positive particle. The arrowhead points to a nucleolus in I-K. Scale bars: 5 µm.
Fig. 3. Nuclear particles in isolated Xenopus nuclei (GVs) have overlapping but distinctive reactivity to amyloid detecting antibodies and thio-T. Isolated GVs were examined using an anti-oligomeric amyloid antibody A11 and particle identifying antibodies. Panel (A) shows a low magnification view of a GV using A11 (green) and anti-nucleolin (red) antibodies. Arrows point to some of the many nucleolin negative, A11 positive particles. (B-E) are higher magnification images of a single nucleolus with (B) representing the composite of (C) anti-nucleolin (red), (D) A11 antibody (green) and (E) anti-dsDNA (blue) staining. The arrowhead points to an A11 positive sub structure. Scale bars (A) 500µm and (B-E) 10µm. Coilin positive particles, histone locus bodies (F-G) and pearls (H-I) are shown as overlays of coilin (red) and A11 (green) in (F and H). The A11 signal of the histone locus body (G) is higher than that of the pearl (I). Scale bars: 5µm. The composite image of A11 and anti-SC35 used to detect speckles in (J) highlights the variable intensity of the A11 signals. In (J) speckles with low A11 signal are indicated with arrowheads and those with more robust A11 signal with arrows. Scale bar: 50μm.
Fig. 4. Maintenance of nucleolin and thio-T staining of isolated Xenopus nuclei (GVs) is RNA dependent. (A-C) Alexa Fluor 568 Phalloidin-stained (red) stage V-VI Xenopus GVs were left untreated (A) or treated with RNase A (B) or Xrn1 (C) for 30 min in the presence of 50 μM thio-T (green). Scale bars: 100 μm. (D-F) Untreated (D) or RNase A-treated (E) GVs were immunostained for nucleolin (magenta). (F) Dark field image nucleus. Scale bars: 100 μm.
Audas,
Immobilization of proteins in the nucleolus by ribosomal intergenic spacer noncoding RNA.
2012, Pubmed
Audas,
Immobilization of proteins in the nucleolus by ribosomal intergenic spacer noncoding RNA.
2012,
Pubmed
Chen,
Nucleolar components involved in ribosome biogenesis cycle between the nucleolus and nucleoplasm in interphase cells.
2001,
Pubmed
Chernoff,
Role of the chaperone protein Hsp104 in propagation of the yeast prion-like factor [psi+].
1995,
Pubmed
Decker,
P-bodies and stress granules: possible roles in the control of translation and mRNA degradation.
2012,
Pubmed
Di Domizio,
Nucleic acid-containing amyloid fibrils potently induce type I interferon and stimulate systemic autoimmunity.
2012,
Pubmed
Di Domizio,
Binding with nucleic acids or glycosaminoglycans converts soluble protein oligomers to amyloid.
2012,
Pubmed
Feric,
A nuclear F-actin scaffold stabilizes ribonucleoprotein droplets against gravity in large cells.
2013,
Pubmed
,
Xenbase
Franke,
A nucleolar skeleton of protein filaments demonstrated in amplified nucleoli of Xenopus laevis.
1981,
Pubmed
,
Xenbase
Franzen,
The temperature stability of egg yolk high density lipoprotein.
1970,
Pubmed
Gallo,
Processing bodies and germ granules are distinct RNA granules that interact in C. elegans embryos.
2008,
Pubmed
Groenning,
Binding mode of Thioflavin T and other molecular probes in the context of amyloid fibrils-current status.
2010,
Pubmed
Halfmann,
Prions are a common mechanism for phenotypic inheritance in wild yeasts.
2012,
Pubmed
Handwerger,
Cajal bodies, nucleoli, and speckles in the Xenopus oocyte nucleus have a low-density, sponge-like structure.
2005,
Pubmed
,
Xenbase
KARASAKI,
Studies on amphibian yolk 1. The ultrastructure of the yolk platelet.
1963,
Pubmed
Kato,
Cell-free formation of RNA granules: low complexity sequence domains form dynamic fibers within hydrogels.
2012,
Pubmed
Kayed,
Fibril specific, conformation dependent antibodies recognize a generic epitope common to amyloid fibrils and fibrillar oligomers that is absent in prefibrillar oligomers.
2007,
Pubmed
Kiseleva,
Actin- and protein-4.1-containing filaments link nuclear pore complexes to subnuclear organelles in Xenopus oocyte nuclei.
2004,
Pubmed
,
Xenbase
Knowles,
The amyloid state and its association with protein misfolding diseases.
2014,
Pubmed
Maji,
Functional amyloids as natural storage of peptide hormones in pituitary secretory granules.
2009,
Pubmed
Mao,
Biogenesis and function of nuclear bodies.
2011,
Pubmed
March,
Prion-like domains as epigenetic regulators, scaffolds for subcellular organization, and drivers of neurodegenerative disease.
2016,
Pubmed
Mohamad,
The proteins of intra-nuclear bodies: a data-driven analysis of sequence, interaction and expression.
2010,
Pubmed
Monneron,
Fine structural organization of the interphase nucleus in some mammalian cells.
1969,
Pubmed
Newby,
Blessings in disguise: biological benefits of prion-like mechanisms.
2013,
Pubmed
Nizami,
Pearls are novel Cajal body-like structures in the Xenopus germinal vesicle that are dependent on RNA pol III transcription.
2012,
Pubmed
,
Xenbase
Olzscha,
Amyloid-like aggregates sequester numerous metastable proteins with essential cellular functions.
2011,
Pubmed
Rambaran,
Amyloid fibrils: abnormal protein assembly.
2008,
Pubmed
Schmidt,
Nup98 FG domains from diverse species spontaneously phase-separate into particles with nuclear pore-like permselectivity.
2015,
Pubmed
,
Xenbase
Si,
Aplysia CPEB can form prion-like multimers in sensory neurons that contribute to long-term facilitation.
2010,
Pubmed
Spector,
Nuclear speckles.
2011,
Pubmed
Stsiapura,
Thioflavin T as a molecular rotor: fluorescent properties of thioflavin T in solvents with different viscosity.
2008,
Pubmed
Tompa,
Intrinsically disordered proteins: a 10-year recap.
2012,
Pubmed
Weber,
Getting RNA and protein in phase.
2012,
Pubmed
Zappulla,
RNA as a flexible scaffold for proteins: yeast telomerase and beyond.
2006,
Pubmed
