ProsomeCytodistribution Relative to Desmin and Actin Filaments in Dividing C2.7 Myoblasts and during Myotube Formationin Vitro

Conto, Flora De; Missorini, S.; Arcangeletti, Cristina; Pinardi, Federica; Montarras, Didier; Pinset, Christian; Vassy, Jany; Géraud, Gérard; Chezzi, Carlo; Scherrer, Klaus

doi:10.1006/excr.1997.3561

Cited by 21 publications

(5 citation statements)

References 59 publications

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“…This model agrees well with EM images showing a strikingly ladder-like cross-linking of rabbit muscle actin filaments by rabbit reticulocyte proteasomes [35]. These data suggest that the actin-proteasome interaction is conserved, which is supported by co-localization of proteasomes with the actin cytoskeleton in many different cell types including Xenopus oocytes [36], epithelial cells and fibroblasts [35], [37], myoblasts [38], and in the sarcomeres of muscle cells [37], [39]–[40].…”

Section: Discussionsupporting

confidence: 86%

Novel Interactions between Actin and the Proteasome Revealed by Complex Haploinsufficiency

et al. 2011

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Saccharomyces cerevisiae has been a powerful model for uncovering the landscape of binary gene interactions through whole-genome screening. Complex heterozygous interactions are potentially important to human genetic disease as loss-of-function alleles are common in human genomes. We have been using complex haploinsufficiency (CHI) screening with the actin gene to identify genes related to actin function and as a model to determine the prevalence of CHI interactions in eukaryotic genomes. Previous CHI screening between actin and null alleles for non-essential genes uncovered ∼240 deleterious CHI interactions. In this report, we have extended CHI screening to null alleles for essential genes by mating a query strain to sporulations of heterozygous knock-out strains. Using an act1Δ query, knock-outs of 60 essential genes were found to be CHI with actin. Enriched in this collection were functional categories found in the previous screen against non-essential genes, including genes involved in cytoskeleton function and chaperone complexes that fold actin and tubulin. Novel to this screen was the identification of genes for components of the TFIID transcription complex and for the proteasome. We investigated a potential role for the proteasome in regulating the actin cytoskeleton and found that the proteasome physically associates with actin filaments in vitro and that some conditional mutations in proteasome genes have gross defects in actin organization. Whole-genome screening with actin as a query has confirmed that CHI interactions are important phenotypic drivers. Furthermore, CHI screening is another genetic tool to uncover novel functional connections. Here we report a previously unappreciated role for the proteasome in affecting actin organization and function.

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Section: Discussionsupporting

confidence: 86%

Novel Interactions between Actin and the Proteasome Revealed by Complex Haploinsufficiency

et al. 2011

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“…One can see that the cellular distribution of p23‐type prosomes differs significantly from that of p27 and p30 prosomes. The p23‐type prosomes are excluded from the greater part of the nuclear space, except spherical internal structures representing the PCs, the RNA PCs [De Conto et al, 1997; Iarovaia et al, 2001]. The p27‐ and p30‐type prosomes are distributed almost randomly both in nuclei and in the cytoplasm.…”

Section: Resultsmentioning

confidence: 99%

RNA‐dependent nuclear matrix contains a 33 kb globin full domain transcript as well as prosomes but no 26S proteasomes

Ioudinkova

Razin

Borunova

et al. 2004

J of Cellular Biochemistry

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Previously, we have shown that in murine myoblasts prosomes are constituents of the nuclear matrix; a major part of the latter was found to be RNase sensitive. Here, we further define the RNA-dependent matrix in avian erythroblastosis virus (AEV) transformed erythroid cells in relation to its structure, presence of specific RNA, prosomes and/or proteasomes. These cells transcribe but do not express globin genes prior to induction. Electron micrographs show little difference in matrices treated with DNase alone or with both, DNase and RNase. In situ hybridization with alpha globin riboprobes shows that this matrix includes globin transcripts. Of particular interest is that, apparently, a nearly 35 kb long globin full domain transcript (FDT), including genes, intergenic regions and a large upstream domain is a part of the RNA-dependent nuclear matrix. The 23K-type of prosomes, previously shown to be co-localized with globin transcripts in the nuclear RNA processing centers, were found all over the nuclear matrix. Other types of prosomes show different distributions in the intact cell but similar distribution patterns on the matrix. Globin transcripts and at least 80% of prosomes disappear from matrices upon RNase treatment. Interestingly, the 19S proteasome modulator complex is insensitive to RNase treatment. Only 20S prosomes but not 26S proteasomes are thus part of the RNA-dependent nuclear matrix. We suggest that giant pre-mRNA and FDTs in processing, aligning prosomes and other RNA-binding proteins are involved in the organization of the dynamic nuclear matrix. It is proposed that the putative function of RNA within the nuclear matrix and, thus, the nuclear dynamic architecture, might explain the giant size and complex organization of primary transcripts and their introns.

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“…In the past few years, there has been an increasing interest for the ubiquitin‐proteasome pathway of protein degradation [33]. This proteolytic pathway is essential for the myogenic differentiation and inhibitors of the proteasome, such as lactacystin, reversibly block both the fusion of L6 myoblasts and the accumulation of muscle‐specific proteins [28,34]; moreover, the subunit composition of proteasomes changes when the dividing C2C12 myoblasts fuse into myotubes [35] and this proteolytic pathway is also implicated in the degradation of MyoD during the G1 phase of the cell cycle [36]. The results presented in the current study are the first direct demonstration of the implication of the ubiquitin‐proteasome proteolytic pathway in the degradation of uPFK‐2.…”

Section: Discussionmentioning

confidence: 99%

Regulation of ubiquitous 6‐phosphofructo‐2‐kinase by the ubiquitin‐proteasome proteolytic pathway during myogenic C2C12 cell differentiation

et al. 2003

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6-Phosphofructo-2-kinase catalyzes the synthesis and degradation of fructose 2,6-bisphosphate, activator of phosphofructokinase-1 and inhibitor of fructose 1,6-bisphosphatase. These properties confer to this bifunctional enzyme a key role in the control of glycolysis and gluconeogenesis. Several mammalian isozymes generated by alternative splicing from four genes, designated pfkfb1^4, have been identi¢ed. The results presented in this study demonstrate the expression of the pfkfb3 gene in C2C12 cells and its downregulation during myogenic cell di¡erentiation. We also show that the decrease of ubiquitous 6-phosphofructo-2-kinase isozyme levels, product of pfkfb3 gene, is due to its enhanced degradation through the ubiquitinproteasome proteolytic pathway. ß

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ProsomeCytodistribution Relative to Desmin and Actin Filaments in Dividing C2.7 Myoblasts and during Myotube Formationin Vitro

Cited by 21 publications

References 59 publications

Novel Interactions between Actin and the Proteasome Revealed by Complex Haploinsufficiency

Novel Interactions between Actin and the Proteasome Revealed by Complex Haploinsufficiency

RNA‐dependent nuclear matrix contains a 33 kb globin full domain transcript as well as prosomes but no 26S proteasomes

Regulation of ubiquitous 6‐phosphofructo‐2‐kinase by the ubiquitin‐proteasome proteolytic pathway during myogenic C2C12 cell differentiation

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