scholarly journals A kinase-dependent checkpoint prevents escape of immature ribosomes into the translating pool

2019 ◽  
Author(s):  
Melissa D. Parker ◽  
Jason C. Collins ◽  
Boguslawa Korona ◽  
Homa Ghalei ◽  
Katrin Karbstein
Keyword(s):  
Cell Viability ◽  
Protein Homeostasis ◽  
Binding Partner ◽  
Rrna Cleavage ◽  
Premature Release

AbstractPremature release of nascent ribosomes into the translating pool must be prevented, as these do not support viability and may be prone to mistakes. Here we show that the kinase Rio1, the nuclease Nob1, and its binding partner Pno1 cooperate to establish a checkpoint that prevents the escape of immature ribosomes into polysomes. Nob1 blocks mRNA recruitment, and rRNA cleavage is required for its dissociation from nascent 40S subunits, thereby setting up a checkpoint for maturation. Rio1 releases Nob1 and Pno1 from pre-40S ribosomes to discharge nascent 40S into the translating pool. Weakly binding Nob1 and Pno1 mutants can bypass the requirement for Rio1, and Pno1 mutants rescue cell viability. In these strains, immature ribosomes escape into the translating pool, where they cause fidelity defects and perturb protein homeostasis. Thus, the Rio1-Nob1-Pno1 network establishes a checkpoint that safeguards against the release of immature ribosomes into the translating pool.

Stew in its Own Juice: Protein Homeostasis Machinery Inhibition Reduces Cell Viability in Multiple Myeloma Cell Lines

2019 ◽  
Vol 19 (2) ◽  
pp. 112-119 ◽  
Author(s):  
Mariana B. de Oliveira ◽  
Luiz F.G. Sanson ◽  
Angela I.P. Eugenio ◽  
Rebecca S.S. Barbosa-Dantas ◽  
Gisele W.B. Colleoni
Keyword(s):  
Multiple Myeloma ◽  
Cell Death ◽  
Cell Viability ◽  
Cell Lines ◽  
Treatment Options ◽  
Compensatory Mechanism ◽  
Protein Homeostasis ◽  
Protein Response ◽  
Rpmi 8226

Introduction:Multiple myeloma (MM) cells accumulate in the bone marrow and produce enormous quantities of immunoglobulins, causing endoplasmatic reticulum stress and activation of protein handling machinery, such as heat shock protein response, autophagy and unfolded protein response (UPR).Methods:We evaluated cell lines viability after treatment with bortezomib (B) in combination with HSP70 (VER-15508) and autophagy (SBI-0206965) or UPR (STF- 083010) inhibitors.Results:For RPMI-8226, after 72 hours of treatment with B+VER+STF or B+VER+SBI, we observed 15% of viable cells, but treatment with B alone was better (90% of cell death). For U266, treatment with B+VER+STF or with B+VER+SBI for 72 hours resulted in 20% of cell viability and both treatments were better than treatment with B alone (40% of cell death). After both triplet combinations, RPMI-8226 and U266 presented the overexpression of XBP-1 UPR protein, suggesting that it is acting as a compensatory mechanism, in an attempt of the cell to handle the otherwise lethal large amount of immunoglobulin overload.Conclusion:Our in vitro results provide additional evidence that combinations of protein homeostasis inhibitors might be explored as treatment options for MM.

scholarly journals PDI Family Members as Guides for Client Folding and Assembly

2020 ◽  
Vol 21 (24) ◽  
pp. 9351
Author(s):  
Shingo Kanemura ◽  
Motonori Matsusaki ◽  
Kenji Inaba ◽  
Masaki Okumura
Keyword(s):  
Endoplasmic Reticulum ◽  
Cell Viability ◽  
Molecular Chaperones ◽  
Protein Disulfide Isomerase ◽  
Family Members ◽  
Secretory Proteins ◽  
Efficient Production ◽  
Protein Homeostasis ◽  
Disulfide Isomerase ◽  
Protein Disulfide

Complicated and sophisticated protein homeostasis (proteostasis) networks in the endoplasmic reticulum (ER), comprising disulfide catalysts, molecular chaperones, and their regulators, help to maintain cell viability. Newly synthesized proteins inserted into the ER need to fold and assemble into unique native structures to fulfill their physiological functions, and this is assisted by protein disulfide isomerase (PDI) family. Herein, we focus on recent advances in understanding the detailed mechanisms of PDI family members as guides for client folding and assembly to ensure the efficient production of secretory proteins.

scholarly journals Bacterial Protein Homeostasis Disruption as a Therapeutic Intervention

2021 ◽  
Vol 8 ◽  
Author(s):  
Laleh Khodaparast ◽  
Guiqin Wu ◽  
Ladan Khodaparast ◽  
Béla Z. Schmidt ◽  
Frederic Rousseau ◽  
...  
Keyword(s):  
Cell Viability ◽  
Protein Misfolding ◽  
Bacterial Infections ◽  
Multidrug Resistant ◽  
Protein Homeostasis ◽  
Bacterial Cells ◽  
Hydrophobic Core ◽  
Turnover Rates ◽  
Root Cause ◽  
Protein Misfolding And Aggregation

Cells have evolved a complex molecular network, collectively called the protein homeostasis (proteostasis) network, to produce and maintain proteins in the appropriate conformation, concentration and subcellular localization. Loss of proteostasis leads to a reduction in cell viability, which occurs to some degree during healthy ageing, but is also the root cause of a group of diverse human pathologies. The accumulation of proteins in aberrant conformations and their aggregation into specific beta-rich assemblies are particularly detrimental to cell viability and challenging to the protein homeostasis network. This is especially true for bacteria; it can be argued that the need to adapt to their changing environments and their high protein turnover rates render bacteria particularly vulnerable to the disruption of protein homeostasis in general, as well as protein misfolding and aggregation. Targeting bacterial proteostasis could therefore be an attractive strategy for the development of novel antibacterial therapeutics. This review highlights advances with an antibacterial strategy that is based on deliberately inducing aggregation of target proteins in bacterial cells aiming to induce a lethal collapse of protein homeostasis. The approach exploits the intrinsic aggregation propensity of regions residing in the hydrophobic core regions of the polypeptide sequence of proteins, which are genetically conserved because of their essential role in protein folding and stability. Moreover, the molecules were designed to target multiple proteins, to slow down the build-up of resistance. Although more research is required, results thus far allow the hope that this strategy may one day contribute to the arsenal to combat multidrug-resistant bacterial infections.

scholarly journals Characteristics of Human OAS1 Isoform Proteins

Viruses ◽  
2020 ◽  
Vol 12 (2) ◽  
pp. 152 ◽  
Author(s):  
Han Di ◽  
Husni Elbahesh ◽  
Margo A. Brinton
Keyword(s):  
Mammalian Cells ◽  
Cellular Localization ◽  
Hek293 Cells ◽  
Poly I:C ◽  
Synthetase Activity ◽  
Binding Partner ◽  
Rrna Cleavage ◽  
Functional Capacities ◽  
Two Hybrid

The human OAS1 (hOAS1) gene produces multiple possible isoforms due to alternative splicing events and sequence variation among individuals, some of which affect splicing. The unique C-terminal sequences of the hOAS1 isoforms could differentially affect synthetase activity, protein stability, protein partner interactions and/or cellular localization. Recombinant p41, p42, p44, p46, p48, p49 and p52 hOAS1 isoform proteins expressed in bacteria were each able to synthesize trimer and higher order 2′-5′ linked oligoadenylates in vitro in response to poly(I:C). The p42, p44, p46, p48 and p52 isoform proteins were each able to induce RNase-mediated rRNA cleavage in response to poly(I:C) when overexpressed in HEK293 cells. The expressed levels of the p42 and p46 isoform proteins were higher than those of the other isoforms, suggesting increased stability in mammalian cells. In a yeast two-hybrid screen, Fibrillin1 (FBN1) was identified as a binding partner for hOAS1 p42 isoform, and Supervillin (SVIL) as a binding partner for the p44 isoform. The p44-SVIL interaction was supported by co-immunoprecipitation data from mammalian cells. The data suggest that the unique C-terminal regions of hOAS1 isoforms may mediate the recruitment of different partners, alternative functional capacities and/or different cellular localization.

Cytoprotective Effect of Tocotrienol-Rich Fraction and α-Tocopherol Vitamin E Isoforms Against Glutamate-Induced Cell Death in Neuronal Cells

2014 ◽  
Vol 84 (3-4) ◽  
pp. 0140-0151 ◽  
Author(s):  
Thilaga Rati Selvaraju ◽  
Huzwah Khaza’ai ◽  
Sharmili Vidyadaran ◽  
Mohd Sokhini Abd Mutalib ◽  
Vasudevan Ramachandran ◽  
...  
Keyword(s):  
Vitamin E ◽  
Cell Viability ◽  
Neuronal Cells ◽  
Positive Control ◽  
Post Treatment ◽  
Mitochondrial Activity ◽  
Before And After ◽  
Pre Treatment ◽  
Tocotrienol Rich Fraction ◽  
Major Mediator

Glutamate is the major mediator of excitatory signals in the mammalian central nervous system. Extreme amounts of glutamate in the extracellular spaces can lead to numerous neurodegenerative diseases. We aimed to clarify the potential of the following vitamin E isomers, tocotrienol-rich fraction (TRF) and α-tocopherol (α-TCP), as potent neuroprotective agents against glutamate-induced injury in neuronal SK-N-SH cells. Cells were treated before and after glutamate injury (pre- and post-treatment, respectively) with 100 - 300 ng/ml TRF/α-TCP. Exposure to 120 mM glutamate significantly reduced cell viability to 76 % and 79 % in the pre- and post-treatment studies, respectively; however, pre- and post-treatment with TRF/α-TCP attenuated the cytotoxic effect of glutamate. Compared to the positive control (glutamate-injured cells not treated with TRF/α-TCP), pre-treatment with 100, 200, and 300 ng/ml TRF significantly improved cell viability following glutamate injury to 95.2 %, 95.0 %, and 95.6 %, respectively (p < 0.05).The isomers not only conferred neuroprotection by enhancing mitochondrial activity and depleting free radical production, but also increased cell viability and recovery upon glutamate insult. Our results suggest that vitamin E has potent antioxidant potential for protecting against glutamate injury and recovering glutamate-injured neuronal cells. Our findings also indicate that both TRF and α-TCP could play key roles as anti-apoptotic agents with neuroprotective properties.

Assessment of the properties of the essential oil from Ridolfia segetum Moris (Portugal) on cancer cell viability

Planta Medica ◽  
2014 ◽  
Vol 80 (16) ◽  
Author(s):  
J Poças ◽  
M Lemos ◽  
C Cabral ◽  
C Cavaleiro ◽  
MT Cruz ◽  
...  
Keyword(s):  
Essential Oil ◽  
Cell Viability ◽  
Cancer Cell

Effects of novel phenolic chalcone derivatives upon MCF-7 Cell viability

Planta Medica ◽  
2016 ◽  
Vol 81 (S 01) ◽  
pp. S1-S381
Author(s):  
A Hussain ◽  
M Grootveld ◽  
R Arroo ◽  
K Beresford ◽  
K Ruparelia ◽  
...  
Keyword(s):  
Cell Viability ◽  
Chalcone Derivatives ◽  
Mcf 7
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