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Molecular adaptation to resistance exercise
Published in Adam P. Sharples, James P. Morton, Henning Wackerhage, Molecular Exercise Physiology, 2022
Beyond the acute regulation of the activity of the ribosome (the amount of protein synthesized per mRNA), mTORC1 can also regulate the number of ribosomes, or the translational capacity of the cell. mTORC1 regulates ribosome mass through the phosphorylation of a key ribosomal RNA transcription factor (upstream binding factor; UBF) and the preferential translation of ribosomal proteins. The transcription of ribosomal DNA is so essential to the function of cells that it has a specialized RNA polymerase (POL I) whose only role is to translate rDNA into the 47S pre-ribosomal RNA. The polycistronic 47S rRNA is then cleaved into the mature 5, 5.8, 18 and 28S rRNAs that make up ~80% of all the RNA in a mammalian cell (53). The transcription of rDNA is thought to be the first step in ribosome biogenesis (the production of new ribosomes) and this process is regulated by the protooncogene myc, and the transcription factors SL1 and UBF. Important for the regulation of ribosome biogenesis in response to resistance exercise, myc transcription increases, and the transcriptional activity of UBF is increased in response to phosphorylation by S6K1. In fact, activation of S6K1 is enough to drive ribosome biogenesis (54). So, following resistance exercise, UBF phosphorylation increases in relation to increased ribosomal RNA synthesis (52).
Resistance Exercise Training and The Regulation of Muscle Protein Synthesis
Published in Peter M. Tiidus, Rebecca E. K. MacPherson, Paul J. LeBlanc, Andrea R. Josse, The Routledge Handbook on Biochemistry of Exercise, 2020
Nathan Hodson, Daniel R. Moore, Chris McGlory
Ribosomes are organelles which act to produce peptide chains corresponding to an mRNA strand, and therefore an increase in their content or capacity would elevate the rates at which new muscle proteins could be produced. The two predominant ways this may occur are through (1) an increase in the number of ribosomes bound to a single mRNA strand, that is, upon full activation the distance between ribosomes on an mRNA strand can shorten from ∼90 to ∼30 nucleotides (106) and (2) an elevated total content of ribosomes, both of which increase the protein yield per strand of mRNA. Mechanistically, ribosomal biogenesis is regulated by a series of transcription factors which act to elevate the rates at which ribosomal RNA (rRNA) and mRNA corresponding to ribosomal proteins are transcribed (106). One such transcription factor is c-myc which regulates both rRNA and ribosomal protein mRNA expression (33, 92). Overexpression of this transcription factor elevates rRNA levels and ribosomal protein content (92), whereas its inhibition elicits reductions in such parameters (33). Research regarding the upstream regulation of this transcription factor is slightly contentious, with data suggesting both mTORC1-dependent (53) and -independent (5) post-translational modifications. Nevertheless, this mechanism is implicated in the regulation of ribosomal biogenesis and is reported to be sensitive to contraction, albeit in rodent skeletal muscle (111).
Diamond–Blackfan Anemia
Published in Dongyou Liu, Handbook of Tumor Syndromes, 2020
Ribosome is a cellular structure involved in the translation of messenger RNA (mRNA) to an amino acid sequence (protein). In eukaryotes, ribosome (measuring 80S in size) is separated into the small (40S) and the large (60S) subunit, each of which consists of ribosomal RNA (rRNA) and RP. The large 60S subunit comprises a 5S rRNA, a 28S rRNA, a 5.8S subunit, and ∼46 RP (or RPL, i.e., RP associated with large ribosomal subunit); whereas the small 40S subunit contains 18S rRNA and ∼33 RP (or RPS, i.e., RP associated with small ribosomal subunit). During ribosome biogenesis, RP are synthesized by RP genes in pre-existing ribosomes in the cytoplasm and transferred into the nucleus to assemble with rRNA for new ribosomes. In addition, some RP take part in signaling pathways within the cell that regulate cell division and control apoptosis [9–13].
Long-term 1800MHz electromagnetic radiation did not induce Balb/c-3T3 cells malignant transformation
Published in Electromagnetic Biology and Medicine, 2021
Zhen Ding, Xiaoyong Xiang, Jintao Li, Shuicai Wu
The PPI network analysis inplied that there are a strong interaction protein network of ribosomal proteins (RPs) and minichromosome maintenance cmplex (Mcms). Ribosome biogenesis and protein translation are finely coordinated with and essential for cell growth, proliferation, differentiation, and animal development. Highly proliferating cancer cells demand a huge amount of proteins, which means that cancer cells need more highly efficient ribosome translational machineries than normal cells (Ruggero and Pandolfi 2003; Silvera et al. 2010). Many RPs have been found to be up-regulated at either mRNA or protein level in various human tumors (Shuda et al. 2000; Kondoh et al. 2001; Artero-Castro et al. 2011; Chen and Dittmer 2011; Dong et al. 2019). Besides, the minichromosome maintenance family (MCMs) plays a central role in the replication, as replicative DNA helicase, and forms a hexameric ring-shaped complex around DNA. Studies have indicated that MCM proteins are highly expressed in several types of cancers, such as lung, breast, colon, and other cancers (Giaginis et al. 2009; Liu et al. 2017; Shetty et al. 2005). ZK Liu et al (Liu et al. 2018) found that MCM6 was identified as a driver of S/G2 cell cycle progression and a potential diagnostic and prognostic marker in HCC.
SILAC-based quantitative proteomics identifies size-dependent molecular mechanisms involved in silver nanoparticles-induced toxicity
Published in Nanotoxicology, 2019
M. N. Fernández, R. Muñoz-Olivas, J. L. Luque-Garcia
In eukaryotic cells, ribosome biogenesis is a complex process in which a long pre-rRNA is transcribed and processed to mature rRNA. Many trans-acting factors and ribosomal proteins are assembled into pre-ribosomes during processing of pre-rRNA (Thomson, Ferreira-Cerca, and Hurt 2013). In agreement with the results commented above, we found in our SILAC experiment several downregulated proteins involved in rRNA maturation and ribosome assembly, which supports the ribosome biogenesis disruption induced by AgNP10 exposure. Such is the case of SERBP1 (RSILAC = −1.30), which has been identified as a pre-rRNA processing factor (Tafforeau et al. 2013); RAC1 (RSILAC = −1.44), a GTP-binding protein belonging to the Rho family of small GTPases that is involved in rRNA synthesis (Xu et al. 2013); NAT1 (RSILAC = −1.51), which is one of the catalytic subunits of NATA and plays a crucial role in the 60S ribosomal subunit biogenesis (Wan et al. 2013); HNRNPL (RSILAC = −1.41) and HNRPRF (RSILAC = −1.37), which interact with B23, a well known nucleolar protein involved in rRNA transcription (D’Agostino, Caracciolo, and Giordano 2010); and RPS15A (RSILAC = −1.37), a subunit of the 40S ribosomal protein that modulates ribosome assembly and translation, and whose downregulation suppresses cell growth and proliferation (Zhao et al. 2015).
Ribosomopathies and cancer: pharmacological implications
Published in Expert Review of Clinical Pharmacology, 2022
Gazmend Temaj, Sarmistha Saha, Shpend Dragusha, Valon Ejupi, Brigitta Buttari, Elisabetta Profumo, Lule Beqa, Luciano Saso
Ribosome biogenesis is a highly coordinated cellular process involving a multitude of macromolecular components, leading to the stoichiometric assembly of ribosomes. Box C/D and H/ACA are RNPs that play pivotal roles in rRNA maturation. Box C/D snoRNP is composed of the methyltransferase fibrillarin (FBL), the function of which is not limited to maturation. It has also been shown to be involved in chaperoning and endo- and exonucleolytic cleavage of pre-rRNA [43]. Other proteins are also implicated in rRNA processing and ribosome biogenesis, and often exert several extra-ribosomal functions. One of these is nucleolin (NCL), a multifunctional phosphoprotein that interacts with the promoter and coding regions to facilitate transcription elongation by Pol I [44,45]. It plays a key role in rRNA maturation by binding to a specific site in the 5’-ETS region in the pre-rRNA, and cleavage of this site facilitates the action of its interacting partner [44,46]. NCL is also shown to participate in the pre-ribosome assembly by interacting with ribosomal proteins [46,47]. Another protein involved in ribosome biogenesis is nucleophosmin (NPM). NPM, like NCL, is a chaperone with the ability to stimulate rRNA [48]. It is involved in the cleavage of the pre-rRNA in the ITS2 region and promotes the release of 28S rRNA [49]. NPM has been shown to be responsible for ribosomal protein transport, such as the nuclear export of RPL5/uL18 and pre-ribosomal subunits [50,51]. Different studies have demonstrated that NPM is also involved in many other cellular processes such as centrosome duplication, cell cycle regulation, and genome stability [52]. NPM is degraded by interaction with ARF, which coincides with the inhibition of ribosome biogenesis [53]. NPM also displays pro-apoptotic activity due to its ability to bind to the pro-apoptotic BAX protein [54]. Ribosomal protein import from the nucleus is an energy-dependent process that is facilitated by several other proteins of the β-karyopherin family. Importin-7 is involved in the nuclear transport of ribosomal proteins, including RPL4/uL4, RPL6/eL6, and RPL23A/uL23 [55]. Similar to the nuclear import of ribosomal proteins, the export of ribosomal proteins is also an energy-dependent process, in which β-karyopherin family proteins play a crucial role. Exportin-1 is involved in this process and can export both pre-ribosomal subunits. Subsequently, both subunits undergo maturation in the cytoplasm [55].