scholarly journals The combination of mitogenic stimulation and cell cycle arrest induces senescence in equine and human cartilage explants

2020 ◽  
Author(s):  
Michaela E. Copp ◽  
Margaret C. Flanders ◽  
Rachel Gagliardi ◽  
Jessica M. Gilbertie ◽  
Garrett A. Sessions ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Articular Cartilage ◽  
Cell Cycle Arrest ◽  
Cartilage Explants ◽  
Human Cartilage ◽  
Mitogenic Stimulation ◽  
Cycle Arrest ◽  
Inflammatory Molecules ◽  
Matrix Degrading Enzymes

AbstractObjectiveCellular senescence is a phenotypic state characterized by stable cell-cycle arrest, enhanced lysosomal activity, and the secretion of inflammatory molecules and matrix degrading enzymes. Senescence has been implicated in osteoarthritis (OA) pathophysiology; however, the mechanisms that drive senescence induction in cartilage and other joint tissues are unknown. While numerous physiological signals are capable of initiating the senescence phenotype, one emerging theme is that growth-arrested cells convert to senescence in response to sustained mitogenic stimulation. The goal of this study was to develop an in vitro articular cartilage explant model to investigate the mechanisms of senescence induction.DesignThis study utilized healthy articular cartilage derived from cadaveric equine stifles and human ankles. Explants were irradiated or treated with palbociclib to initiate cell cycle arrest, and mitogenic stimulation was provided by serum-containing medium (horse) and the inclusion of growth factors (human). The primary readout of senescence was a quantitative flow cytometry assay to detect senescence-associated β galactosidase activity (SA-β-gal).ResultsIrradiation of equine explants caused 25.39% of cells to express high levels of SA-β-gal, as compared to 3.82% in control explants (p=0.0031). For human cartilage, explants that received both mitogenic stimulation and cell cycle arrest showed increased rates of senescence induction as compared to baseline control (7.16% vs. 2.34% SA-β-gal high, p=0.0007).ConclusionsTreatment of cartilage explants with mitogenic stimuli in the context of cell-cycle arrest reliably induces high levels of SA-β gal activity, which provides a physiologically relevant model system to investigate the mechanisms of senescence induction.

scholarly journals HIV-1 Vpr activates host CRL4-DCAF1 E3 ligase to degrade histone deacetylase SIRT7

2021 ◽  
Vol 18 (1) ◽  
Author(s):  
Xiaohong Zhou ◽  
Christina Monnie ◽  
Maria DeLucia ◽  
Jinwoo Ahn
Keyword(s):  
Cell Cycle ◽  
Dna Repair ◽  
Cell Cycle Arrest ◽  
Histone Deacetylase ◽  
E3 Ligase ◽  
Cycle Arrest ◽  
Wide Range ◽  
In Vitro Reconstitution ◽  
Hiv 1

Abstract Background Vpr is a virion-associated protein that is encoded by lentiviruses and serves to counteract intrinsic immunity factors that restrict infection. HIV-1 Vpr mediates proteasome-dependent degradation of several DNA repair/modification proteins. Mechanistically, Vpr directly recruits cellular targets onto DCAF1, a substrate receptor of Cullin 4 RING E3 ubiquitin ligase (CRL4) for poly-ubiquitination. Further, Vpr can mediate poly-ubiquitination of DCAF1-interacting proteins by the CRL4. Because Vpr-mediated degradation of its known targets can not explain the primary cell-cycle arrest phenotype that Vpr expression induces, we surveyed the literature for DNA-repair-associated proteins that interact with the CRL4-DCAF1. One such protein is SIRT7, a deacetylase of histone 3 that belongs to the Sirtuin family and regulates a wide range of cellular processes. We wondered whether Vpr can mediate degradation of SIRT7 via the CRL4-DCAF1. Methods HEK293T cells were transfected with cocktails of plasmids expressing DCAF1, DDB1, SIRT7 and Vpr. Ectopic and endogeneous levels of SIRT7 were monitered by immunoblotting and protein–protein interactions were assessed by immunoprecipitation. For in vitro reconstitution assays, recombinant CRL4-DCAF1-Vpr complexes and SIRT7 were prepared and poly-ubiqutination of SIRT7 was monitored with immunoblotting. Results We demonstrate SIRT7 polyubiquitination and degradation upon Vpr expression. Specifically, SIRT7 is shown to interact with the CRL4-DCAF1 complex, and expression of Vpr in HEK293T cells results in SIRT7 degradation, which is partially rescued by CRL inhibitor MNL4924 and proteasome inhibitor MG132. Further, in vitro reconstitution assays show that Vpr induces poly-ubiquitination of SIRT7 by the CRL4-DCAF1. Importantly, we find that Vpr from several different HIV-1 strains, but not HIV-2 strains, mediates SIRT7 poly-ubiquitination in the reconstitution assay and degradation in cells. Finally, we show that SIRT7 degradation by Vpr is independent of the known, distinctive phenotype of Vpr-induced cell cycle arrest at the G2 phase, Conclusions Targeting histone deacetylase SIRT7 for degradation is a conserved feature of HIV-1 Vpr. Altogether, our findings reveal that HIV-1 Vpr mediates down-regulation of SIRT7 by a mechanism that does not involve novel target recruitment to the CRL4-DCAF1 but instead involves regulation of the E3 ligase activity.

Synthesis, cytotoxicity in vitro, apoptosis, cell cycle arrest and comet assay of asymmetry ruthenium(II) complexes

Polyhedron ◽  
2016 ◽  
Vol 106 ◽  
pp. 115-124 ◽  
Author(s):  
Cheng Zhang ◽  
Chuan-Chuan Zeng ◽  
Shang-Hai Lai ◽  
De-Gang Xing ◽  
Wei Li ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Comet Assay ◽  
Cell Cycle Arrest ◽  
Cycle Arrest

Evaluation of deoxynivalenol-induced toxic effects on DF-1 cells in vitro: Cell-cycle arrest, oxidative stress, and apoptosis

2014 ◽  
Vol 37 (1) ◽  
pp. 141-149 ◽  
Author(s):  
Daotong Li ◽  
Yaqiong Ye ◽  
Shaoqing Lin ◽  
Li Deng ◽  
Xiaolong Fan ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Cell Cycle ◽  
Cell Cycle Arrest ◽  
Toxic Effects ◽  
Cycle Arrest

scholarly journals Apoptosis Induction, Cell Cycle Arrest and in Vitro Anticancer Activity of Gonothalamin in a Cancer Cell Lines

2012 ◽  
Vol 13 (10) ◽  
pp. 5131-5136 ◽  
Author(s):  
Aied M. Alabsi ◽  
Rola Ali ◽  
Abdul Manaf Ali ◽  
Sami Abdo Radman Al-Dubai ◽  
Hazlan Harun ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Anticancer Activity ◽  
Cell Cycle Arrest ◽  
Cell Lines ◽  
Cancer Cell ◽  
Cancer Cell Lines ◽  
Apoptosis Induction ◽  
Cycle Arrest

scholarly journals The innate immune sensor Toll-like receptor 2 controls the senescence-associated secretory phenotype

2018 ◽  
Author(s):  
Priya Hari ◽  
Fraser R. Millar ◽  
Nuria Tarrats ◽  
Jodie Birch ◽  
Curtis J. Rink ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Cell Cycle Arrest ◽  
Innate Immune ◽  
Toll Like Receptor ◽  
Cycle Arrest ◽  
Secretory Phenotype ◽  
Immune Sensing ◽  
Molecular Patterns ◽  
Innate Immune Sensing

ABSTRACTCellular senescence is a stress response program characterised by a robust cell cycle arrest and the induction of a pro-inflammatory senescence-associated secretory phenotype (SASP) that is triggered through an unknown mechanism. Here, we show that during oncogene-induced senescence (OIS), the Toll-like receptor TLR2 and its partner TLR10 are key mediators of senescence in vitro and in murine models. TLR2 promotes cell cycle arrest by regulating the tumour suppressors p53-p21CIP1, p16INK4a and p15INK4b, and regulates the SASP through the induction of the acute-phase serum amyloids A1 and A2 (A-SAA) that, in turn, function as the damage associated molecular patterns (DAMPs) signalling through TLR2 in OIS. Finally, we found evidence that the cGAS-STING cytosolic DNA sensing pathway primes TLR2 and A-SAA expression in OIS. In summary, we report that innate immune sensing of senescence-associated DAMPs by TLR2 controls the SASP and reinforces the cell cycle arrest program in OIS.

Sign in / Sign up

Export Citation Format

Share Document