The role of expansion segment of human ribosomal protein L35 in nuclear entry, translation activity, and endoplasmic reticulum docking

Chen, In-Jay ChenI.; Wang, I-Ann WangI.; Tai, Lin-Ru; Lin, Alan

doi:10.1139/o08-032

Cited by 14 publications

(12 citation statements)

References 18 publications

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“…However, it could be demonstrated that human L35 r-protein binds to nucle(ol)ar pre-60S r-particles in HeLa cells (44). Consistently, it has also been shown in HeLa cells that L35 is imported to the nucleus due to the presence of a NLS within the C-terminal part of the protein (108). In this study, we present several lines of evidence that yeast L35 assembly occurs in the nucle(ol)us.…”

Section: Discussionsupporting

confidence: 55%

Ribosomal protein L35 is required for 27SB pre-rRNA processing in Saccharomyces cerevisiae

Babiano

Cruz

2010

Nucleic Acids Research

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Ribosome synthesis involves the concomitance of pre-rRNA processing and ribosomal protein assembly. In eukaryotes, this is a complex process that requires the participation of specific sequences and structures within the pre-rRNAs, at least 200 trans-acting factors and the ribosomal proteins. There is little information on the function of individual 60S ribosomal proteins in ribosome synthesis. Herein, we have analysed the contribution of ribosomal protein L35 in ribosome biogenesis. In vivo depletion of L35 results in a deficit in 60S ribosomal subunits and the appearance of half-mer polysomes. Pulse-chase, northern hybridization and primer extension analyses show that processing of the 27SB to 7S pre-rRNAs is strongly delayed upon L35 depletion. Most likely as a consequence of this, release of pre-60S ribosomal particles from the nucleolus to the nucleoplasm is also blocked. Deletion of RPL35A leads to similar although less pronounced phenotypes. Moreover, we show that L35 assembles in the nucleolus and binds to early pre-60S ribosomal particles. Finally, flow cytometry analysis indicated that L35-depleted cells mildly delay the G1 phase of the cell cycle. We conclude that L35 assembly is a prerequisite for the efficient cleavage of the internal transcribed spacer 2 at site C2.

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Section: Discussionsupporting

confidence: 55%

Ribosomal protein L35 is required for 27SB pre-rRNA processing in Saccharomyces cerevisiae

Babiano

Cruz

2010

Nucleic Acids Research

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“…This complexity suggests that many molecules that were not initially imported were added later to the import repertoire in a piecemeal fashion by acquiring a diversity of NLS recognized preferentially by different karyopherins. Some ribosomal proteins show clear evidence of the later addition of NLS in expansion segments [276], an example of the quantum evolutionary impact on ribosomes of the origin of the nuclear envelope earlier postulated [3,70]. Though one might think that replication and repair enzymes and RNA polymerases were among the early molecules imported [3], it remains unclear how many of these, especially RNA polymerase are imported [277]; the case of transcription initiation factors is interesting in emphasizing that in a large macromolecular complex only some (minimally one) constituents needs an NLS - thus TAF10 a component of transcription factor complex TFII (that recognizes TATA boxes) and other transcription regulatory complexes lacks an NLS but is imported by being bound to three proteins with histone fold domains that contain NLS [278]; these histone-fold factors might themselves have evolved from core histones and thus ancestrally would have had NLSs.…”

Section: Results: the Origin Of Mitosis And The Nucleusmentioning

confidence: 99%

Origin of the cell nucleus, mitosis and sex: roles of intracellular coevolution

2010

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BackgroundThe transition from prokaryotes to eukaryotes was the most radical change in cell organisation since life began, with the largest ever burst of gene duplication and novelty. According to the coevolutionary theory of eukaryote origins, the fundamental innovations were the concerted origins of the endomembrane system and cytoskeleton, subsequently recruited to form the cell nucleus and coevolving mitotic apparatus, with numerous genetic eukaryotic novelties inevitable consequences of this compartmentation and novel DNA segregation mechanism. Physical and mutational mechanisms of origin of the nucleus are seldom considered beyond the long-standing assumption that it involved wrapping pre-existing endomembranes around chromatin. Discussions on the origin of sex typically overlook its association with protozoan entry into dormant walled cysts and the likely simultaneous coevolutionary, not sequential, origin of mitosis and meiosis.ResultsI elucidate nuclear and mitotic coevolution, explaining the origins of dicer and small centromeric RNAs for positionally controlling centromeric heterochromatin, and how 27 major features of the cell nucleus evolved in four logical stages, making both mechanisms and selective advantages explicit: two initial stages (origin of 30 nm chromatin fibres, enabling DNA compaction; and firmer attachment of endomembranes to heterochromatin) protected DNA and nascent RNA from shearing by novel molecular motors mediating vesicle transport, division, and cytoplasmic motility. Then octagonal nuclear pore complexes (NPCs) arguably evolved from COPII coated vesicle proteins trapped in clumps by Ran GTPase-mediated cisternal fusion that generated the fenestrated nuclear envelope, preventing lethal complete cisternal fusion, and allowing passive protein and RNA exchange. Finally, plugging NPC lumens by an FG-nucleoporin meshwork and adopting karyopherins for nucleocytoplasmic exchange conferred compartmentation advantages. These successive changes took place in naked growing cells, probably as indirect consequences of the origin of phagotrophy. The first eukaryote had 1-2 cilia and also walled resting cysts; I outline how encystation may have promoted the origin of meiotic sex. I also explain why many alternative ideas are inadequate.ConclusionNuclear pore complexes are evolutionary chimaeras of endomembrane- and mitosis-related chromatin-associated proteins. The keys to understanding eukaryogenesis are a proper phylogenetic context and understanding organelle coevolution: how innovations in one cell component caused repercussions on others.ReviewersThis article was reviewed by Anthony Poole, Gáspár Jékely and Eugene Koonin.

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“…Recently information on the structure of eukaryotic ribosome has greatly progressed [10], and the characteristics of the expansion segments (ES) of ribosomal rRNA and ribosomal peptides in eukaryotic ribosome have been gradually revealed [10], [11], [12], [13], [14]. These studies have suggested that the ES is often exposed on the surface of ribosome particle [10], [11], [12], [13], [14], [15].…”

Section: Introductionmentioning

confidence: 99%

“…These studies have suggested that the ES is often exposed on the surface of ribosome particle [10], [11], [12], [13], [14], [15]. Thus, the potential surface property of an ES might provide a useful means of generating a surface-specific antibody against eukaryotic ribosome particles.…”

Section: Introductionmentioning

confidence: 99%

Ribosome Distribution in HeLa Cells during the Cell Cycle

Yuan-Jhih¹,

Lee²,

Lin

2012

PLoS ONE

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In this study, we employed a surface-specific antibody against the large ribosome subunit to investigate the distribution of ribosomes in cells during the cell cycle. The antibody, anti-L7n, was raised against an expansion segment (ES) peptide from the large subunit ribosomal protein L7, and its ribosome-surface specificity was evident from the positive immuno-reactivity of ribosome particles and the detection of 60 S immune-complex formation by an immuno-electron microscopy. Using immunofluorescent staining, we have microscopically revealed that ribosomes are dispersed in the cytoplasm of cells throughout all phases of the cell cycle, except at the G2 phase where ribosomes show a tendency to gather toward the nuclear envelope. The finding in G2 cells was confirmed by electron microscopy using a morphometric assay and paired t test. Furthermore, further observations have shown that ribosomes are not distributed immune-fluorescently with nuclear envelope markers including the nuclear pore complex, the integral membrane protein gp210, the inner membrane protein lamin B2, and the endoplasm reticulum membrane during cell division we propose that the mechanism associated with ribosome segregation into daughter cells could be independent of the processes of disassembly and reassembly of the nuclear envelope.

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The role of expansion segment of human ribosomal protein L35 in nuclear entry, translation activity, and endoplasmic reticulum docking

Cited by 14 publications

References 18 publications

Ribosomal protein L35 is required for 27SB pre-rRNA processing in Saccharomyces cerevisiae

Ribosomal protein L35 is required for 27SB pre-rRNA processing in Saccharomyces cerevisiae

Origin of the cell nucleus, mitosis and sex: roles of intracellular coevolution

Ribosome Distribution in HeLa Cells during the Cell Cycle

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