The exonuclease ISG20 mainly localizes in the nucleolus and the Cajal (Coiled) bodies and is associated with nuclear SMN protein-containing complexes

By conventional electron microscopy, the formed elements of the nuclear interior include the nucleolus, chromatin, interchromatin granules, perichromatin granules, perichromatin fibrils, and various types of nuclear bodies (Figs. 1a-c). Of these structures, all have been reasonably well characterized structurally and functionally except for nuclear bodies. The most common types of nuclear bodies are simple nuclear bodies and coiled bodies (Figs. 1a,c). Since nuclear bodies are small in size (0.2-1.0 μm in diameter) and infrequent in number, they are often overlooked or simply not observed in any random thin section. The rat liver hepatocyte in Fig. 1b is a case in point. Historically, nuclear bodies are more prominent in hyperactive cells, they often occur in proximity to nucleoli (Fig. 1c), and sometimes they are observed to “bud off” from the nucleolar surface.

Download Full-text

Nuclear coiled bodies and the nucleolus

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100167834 ◽

1994 ◽

Vol 52 ◽

pp. 20-21

Author(s):

K. Brasch ◽

J. Williams ◽

D. Gallo ◽

T. Lee ◽

R. L. Ochs

Keyword(s):

Mouse Liver ◽

Nuclear Body ◽

Nuclear Bodies ◽

Model Systems ◽

Coiled Body ◽

Rrna Processing ◽

Malignant Cells ◽

Sm Proteins ◽

Coiled Bodies ◽

Unique Protein

Though first described in 1903 by Ramon-y-Cajal as silver-staining “accessory bodies” to nucleoli, nuclear bodies were subsequently rediscovered by electron microscopy about 30 years ago. Nuclear bodies are ubiquitous, but seem most abundant in hyperactive and malignant cells. The best studied type of nuclear body is the coiled body (CB), so termed due to characteristic morphology and content of a unique protein, p80-coilin (Fig.1). While no specific functions have as yet been assigned to CBs, they contain spliceosome snRNAs and proteins, and also the nucleolar protein fibrillarin. In addition, there is mounting evidence that CBs arise from or are generated near the nucleolus and then migrate into the nucleoplasm. This suggests that as yet undefined links may exist, between nucleolar pre-rRNA processing events and the spliceosome-associated Sm proteins in CBs.We are examining CB and nucleolar changes in three diverse model systems: (1) estrogen stimulated chick liver, (2) normal and neoplastic cells, and (3) polyploid mouse liver.

Download Full-text

The influence of storage parameters on measurement of survival motor neuron (SMN) protein levels: Implications for pre-clinical studies and clinical trials for spinal muscular atrophy

Neuromuscular Disorders ◽

10.1016/j.nmd.2014.05.013 ◽

2014 ◽

Vol 24 (11) ◽

pp. 973-977 ◽

Cited By ~ 4

Author(s):

Gillian Hunter ◽

Sarah L. Roche ◽

Eilidh Somers ◽

Heidi R. Fuller ◽

Thomas H. Gillingwater

Keyword(s):

Clinical Trials ◽

Spinal Muscular Atrophy ◽

Motor Neuron ◽

Clinical Studies ◽

Muscular Atrophy ◽

Survival Motor Neuron ◽

Protein Levels ◽

Smn Protein

Download Full-text

Nuclear fibroblast growth factor-2 interacts specifically with splicing factor SF3a66

Biological Chemistry ◽

10.1515/bc.2004.156 ◽

2004 ◽

Vol 385 (12) ◽

pp. 1203-1208 ◽

Cited By ~ 13

Author(s):

Susanne Gringel ◽

Jeroen van Bergeijk ◽

Kirsten Haastert ◽

Claudia Grothe ◽

Peter Claus

Keyword(s):

Growth Factor ◽

Fibroblast Growth Factor ◽

Splicing Factor ◽

Fibroblast Growth Factor 2 ◽

Interacting Proteins ◽

Fibroblast Growth ◽

Extracellular Signaling ◽

C Terminus ◽

Assembly Factor ◽

Smn Protein

Abstract Fibroblast growth factor 2 (FGF-2) has a dual role as a classical extracellular signaling protein and as an intracellular factor. Isoforms of FGF-2, resulting from alternatively used start codons on one mRNA species, locate differentially to nuclear compartments. In this study we aimed to analyze functions of intracellular FGF-2 by identification of interacting proteins. We identified the 66-kDa subunit of splicing factor 3a (SF3a66) as a binding partner in a yeast two-hybrid screen and confirmed this interaction by pull-down assays. The splicing factor interacted with the 18-kDa (FGF-218) and with the 23-kDa (FGF-223) isoforms, indicating an interaction with a domain common to both isoforms. Moreover, FGF-2 interacted with the C-terminus of SF3a66, a sequence that has not previously been assigned a functional role. In a functional neurite outgrowth assay, SF3a66 enhanced neurite lengths similar to FGF-218. We have previously identified the spliceosomal assembly factor survival of motoneuron (SMN) protein as a protein interacting specifically with the FGF-223 isoform [Claus et al., J. Biol. Chem. 278 (2003), 479–485]. The identification of two FGF-2 interacting proteins from the same biochemical pathway suggests a novel intranuclear role of FGF-2.

Download Full-text

SMN mRNA and protein levels in peripheral blood

Neurology ◽

10.1212/01.wnl.0000201929.56928.13 ◽

2006 ◽

Vol 66 (7) ◽

pp. 1067-1073 ◽

Cited By ~ 58

Author(s):

C. J. Sumner ◽

S. J. Kolb ◽

G. G. Harmison ◽

N. O. Jeffries ◽

K. Schadt ◽

...

Keyword(s):

Clinical Trials ◽

Spinal Muscular Atrophy ◽

Disease Severity ◽

Peripheral Blood ◽

Muscular Atrophy ◽

Gene Copy ◽

Blood Levels ◽

Type I ◽

Protein Levels ◽

Smn Protein

Background: Clinical trials of drugs that increase SMN protein levels in vitro are currently under way in patients with spinal muscular atrophy.Objective: To develop and validate measures of SMN mRNA and protein in peripheral blood and to establish baseline SMN levels in a cohort of controls, carriers, and patients of known genotype, which could be used to follow response to treatment.Methods: SMN1 and SMN2 gene copy numbers were determined in blood samples collected from 86 subjects. Quantitative reverse transcription PCR was used to measure blood levels of SMN mRNA with and without exon 7. A cell immunoassay was used to measure blood levels of SMN protein.Results: Blood levels of SMN mRNA and protein were measured with high reliability. There was little variation in SMN levels in individual subjects over a 5-week period. Levels of exon 7-containing SMN mRNA and SMN protein correlated with SMN1 and SMN2 gene copy number. With the exception of type I SMA, there was no correlation between SMN levels and disease severity.Conclusion: SMN mRNA and protein levels can be reliably measured in the peripheral blood and used during clinical trials in spinal muscular atrophy, but these levels do not necessarily predict disease severity.

Download Full-text

Argyrophilic grain disease: An underestimated tauopathy

Dementia & Neuropsychologia ◽

10.1590/s1980-57642015dn91000002 ◽

2015 ◽

Vol 9 (1) ◽

pp. 2-8 ◽

Cited By ~ 19

Author(s):

Roberta Diehl Rodriguez ◽

Lea Tenenholz Grinberg

Keyword(s):

Alzheimer’S Disease ◽

Alzheimer's Disease ◽

Defense Mechanism ◽

Neuropsychiatric Symptoms ◽

Argyrophilic Grain Disease ◽

Coiled Bodies ◽

Pathologic Features ◽

High Prevalence ◽

Argyrophilic Grain ◽

Argyrophilic Grains

Argyrophilic grain disease (AGD) is an under-recognized, distinct, highly frequent sporadic tauopathy, with a prevalence reaching 31.3% in centenarians. The most common AGD manifestation is slowly progressive amnestic mild cognitive impairment, accompanied by a high prevalence of neuropsychiatric symptoms. AGD diagnosis can only be achieved postmortem based on the finding of its three main pathologic features: argyrophilic grains, oligodendrocytic coiled bodies and neuronal pretangles. AGD is frequently seen together with Alzheimer's disease-type pathology or in association with other neurodegenerative diseases. Recent studies suggest that AGD may be a defense mechanism against the spread of other neuropathological entities, particularly Alzheimer's disease. This review aims to provide an in-depth overview of the current understanding on AGD.

Download Full-text

Calpain Inhibition Increases SMN Protein in Spinal Cord Motoneurons and Ameliorates the Spinal Muscular Atrophy Phenotype in Mice

Molecular Neurobiology ◽

10.1007/s12035-018-1379-z ◽

2018 ◽

Vol 56 (6) ◽

pp. 4414-4427 ◽

Cited By ~ 4

Author(s):

Sandra de la Fuente ◽

Alba Sansa ◽

Ambika Periyakaruppiah ◽

Ana Garcera ◽

Rosa M. Soler

Keyword(s):

Spinal Cord ◽

Spinal Muscular Atrophy ◽

Muscular Atrophy ◽

Smn Protein ◽

Calpain Inhibition

Download Full-text

Regulation of SMN Protein Stability

Molecular and Cellular Biology ◽

10.1128/mcb.01262-08 ◽

2008 ◽

Vol 29 (5) ◽

pp. 1107-1115 ◽

Cited By ~ 173

Author(s):

Barrington G. Burnett ◽

Eric Muñoz ◽

Animesh Tandon ◽

Deborah Y. Kwon ◽

Charlotte J. Sumner ◽

...

Keyword(s):

Complex Formation ◽

Protein Stability ◽

Half Life ◽

Muscular Atrophy ◽

Ubiquitin Proteasome System ◽

Protein Product ◽

Smn Complex ◽

A Cell ◽

Smn Protein ◽

Survival Of Motor Neuron

ABSTRACT Spinal muscular atrophy (SMA) is caused by mutations of the survival of motor neuron (SMN1) gene and deficiency of full-length SMN protein (FL-SMN). All SMA patients retain one or more copies of the SMN2 gene, but the principal protein product of SMN2 lacks exon 7 (SMNΔ7) and is unable to compensate for a deficiency of FL-SMN. SMN is known to oligomerize and form a multimeric protein complex; however, the mechanisms regulating stability and degradation of FL-SMN and SMNΔ7 proteins have been largely unexplored. Using pulse-chase analysis, we characterized SMN protein turnover and confirmed that SMN was ubiquitinated and degraded by the ubiquitin proteasome system (UPS). The SMNΔ7 protein had a twofold shorter half-life than FL-SMN in cells despite similar intrinsic rates of turnover by the UPS in a cell-free assay. Mutations that inhibited SMN oligomerization and complex formation reduced the FL-SMN half-life. Furthermore, recruitment of SMN into large macromolecular complexes as well as increased association with several Gemin proteins was regulated in part by protein kinase A. Together, our data indicate that SMN protein stability is modulated by complex formation. Promotion of the SMN complex formation may be an important novel therapeutic strategy for SMA.

Download Full-text

Interactions of U2 Gene Loci and Their Nuclear Transcripts with Cajal (Coiled) Bodies: Evidence for PreU2 within Cajal Bodies

Molecular Biology of the Cell ◽

10.1091/mbc.11.9.2987 ◽

2000 ◽

Vol 11 (9) ◽

pp. 2987-2998 ◽

Cited By ~ 40

Author(s):

Kelly P. Smith ◽

Jeanne Bentley Lawrence

Keyword(s):

Potential Role ◽

Coiled Body ◽

Oligonucleotide Probes ◽

Primary Transcript ◽

U2 Snrna ◽

Rna Foci ◽

Coiled Bodies ◽

Snrna Gene

The Cajal (coiled) body (CB) is a structure enriched in proteins involved in mRNA, rRNA, and snRNA metabolism. CBs have been shown to interact with specific histone and snRNA gene loci. To examine the potential role of CBs in U2 snRNA metabolism, we used a variety of genomic and oligonucleotide probes to visualize in situ newly synthesized U2 snRNA relative to U2 loci and CBs. Results demonstrate that long spacer sequences between U2 coding repeats are transcribed, supporting other recent evidence that U2 transcription proceeds past the 3′ box. The presence of bright foci of this U2 locus RNA differed between alleles within the same nucleus; however, this did not correlate with the loci's association with a CB. Experiments with specific oligonucleotide probes revealed signal for preU2 RNA within CBs. PreU2 was also detected in the locus-associated RNA foci, whereas sequences 3′ of preU2 were found only in these foci, not in CBs. This suggests that a longer primary transcript is processed before entry into CBs. Although this work shows that direct contact of a U2 locus with a CB is not simply correlated with RNA at that locus, it provides the first evidence of new preU2 transcripts within CBs. We also show that, in contrast to CBs, SMN gems do not associate with U2 gene loci and do not contain preU2. Because other evidence indicates that preU2 is processed in the cytoplasm before assembly into snRNPs, results point to an involvement of CBs in modification or transport of preU2 RNA.

Download Full-text