scholarly journals Extensive mechanical tension promotes annulus fibrosus cell senescence through suppressing cellular autophagy

2019 ◽  
Vol 39 (4) ◽  
Author(s):  
Liang Zhao ◽  
Baofang Tian ◽  
Qing Xu ◽  
Cunxin Zhang ◽  
Luo Zhang ◽  
...  
Keyword(s):  
Cell Proliferation ◽  
Protein Expression ◽  
Disc Degeneration ◽  
Cell Biology ◽  
Annulus Fibrosus ◽  
Mechanical Load ◽  
Telomerase Activity ◽  
Cell Senescence ◽  
Mechanical Tension ◽  
Cellular Autophagy

Abstract Background: Mechanical load contributes a lot to the initiation and progression of disc degeneration. Annulus fibrosus (AF) cell biology under mechanical tension remains largely unclear. Objective: The present study was aimed to investigate AF cell senescence under mechanical tension and the potential role of autophagy. Methods: Rat AF cells were cultured and experienced different magnitudes (5% elongation and 20% elongation) of mechanical tension for 12 days. Control AF cells were kept static. Cell proliferation, telomerase activity, cell cycle fraction, and expression of senescence-related molecules (p16 and p53) and matrix macromolecules (aggrecan and collagen I) were analyzed to evaluate cell senescence. In addition, expression of Beclin-1 and LC3, and the ratio of LC3-II to LC3-I were analyzed to investigate cell autophagy. Results: Compared with the control group and 5% tension group, 20% tension group significantly decreased cell proliferation potency and telomerase activity, increased G1/G0 phase fraction, and up-regulated gene/protein expression of p16 and p53, whereas down-regulated gene/protein expression of aggrecan and collagen I. In addition, autophagy-related parameters such as gene/protein expression of Beclin-1 and LC3, and the ratio of LC3-II to LC3-I, were obviously suppressed in the 20% tension group. Conclusion: High mechanical tension promotes AF cell senescence though suppressing cellular autophagy. The present study will help us to better understand AF cell biology under mechanical tension and mechanical load-related disc degeneration.

scholarly journals Mechanical Stretch Induces Annulus Fibrosus Cell Senescence through Activation of the RhoA/ROCK Pathway

2021 ◽  
Vol 2021 ◽  
pp. 1-7
Author(s):  
Li Ning ◽  
Lei Gao ◽  
Fan Zhang ◽  
Xiaoxiao Li ◽  
Tingting Wang
Keyword(s):  
Cell Cycle ◽  
Cell Proliferation ◽  
Annulus Fibrosus ◽  
Coiled Coil ◽  
Mechanical Stretch ◽  
Telomerase Activity ◽  
Cell Senescence ◽  
Central Nucleus ◽  
Biological Behavior ◽  
Signaling Transduction Pathway

Background. Intervertebral disc is responsible for absorbing and transmitting mechanical compression. Under physiological conditions, the peripheral annulus fibrosus (AF) cells are subjected to different magnitudes of transverse mechanical stretch depending on the swelling of the central nucleus pulposus tissue. However, the biological behavior of AF cells under mechanical stretch is not well studied. Objective. This study was performed to study the effects of mechanical tension on AF cell senescence and the potential signaling transduction pathway. Methods. Rat AF cells were made to experience different magnitudes of mechanical stretch (2% elongation and 20% elongation for 4 hours every day at 1 Hz) in a 10-day experiment period. The inhibitor RKI-1447 of the Rho-associated coiled-coil–containing protein kinases (ROCK) was added along with culture medium to investigate its role. Cell proliferation, cell cycle, telomerase activity, and expression of senescence markers (p16 and p53) were analyzed. Results. We found that 20% elongation significantly decreased cell proliferation, promoted G0/G1 cell cycle arrest, decreased telomerase activity, and upregulated mRNA/protein expression of p16 and p53. Moreover, the inhibitor RKI-1447 partly resisted effects of 20% elongation on these parameters of cell senescence. Conclusion. High mechanical stretch obviously induces AF cell senescence through the RhoA/ROCK pathway. This study provides us a deeper understanding on the AF cell’s behavior under mechanical stretch.

scholarly journals Responses of apoptosis and matrix metabolism of annulus fibrosus cells to different magnitudes of mechanical tension in vitro

2019 ◽  
Vol 39 (2) ◽  
Author(s):  
Yanhai Jiang ◽  
Lianqiang Fu ◽  
Yeliang Song
Keyword(s):  
Protein Expression ◽  
Cell Apoptosis ◽  
Annulus Fibrosus ◽  
Caspase 3 ◽  
Mechanical Load ◽  
Control Group ◽  
Mechanical Tension ◽  
Matrix Metabolism ◽  
Apoptosis Ratio

Abstract Background: Annulus fibrosus (AF) is important to confine disc nucleus pulposus (NP) tissue during mechanical load experience. However, the knowledge on AF cell biology under mechanical load is much limited compared with disc NP. Objective: The present study aimed to investigate responses of apoptosis and matrix metabolism of AF cells to different magnitudes of mechanical tension in vitro. Methods: Rat AF cells were subjected to different magnitudes (5, 10, and 20% elongations at a frequency of 1.0 Hz for 6 h per day) of mechanical tension for 7 days. Control AF cells were cultured without mechanical tension. Cell apoptosis ratio, caspase-3 activity, gene/protein expression of apoptosis-related molecules (Bcl-2, Bax, caspase-3/cleaved caspase-3 and cleaved PARP), matrix macromolecules (aggrecan and collagen I) and matrix metabolism-related enzymes (TIMP-1, TIMP-3, MMP-3, and ADAMTS-4) were analyzed. Results: Compared with 5% tension group and control group, 10 and 20% tension groups significantly increased apoptosis ratio, caspase-3 activity, up-regulated gene/protein expression of Bax, caspase-3/cleaved caspase-3, cleaved PARP, MMP-3, and ADAMTS-4, whereas down-regulated gene/protein expression of Bcl-2, aggrecan, collagen I, TIMP-1, and TIMP-3. No significant difference was found in these parameters apart from Bcl-2 expression between the control group and 5% tension group. Conclusion: High mechanical tension promotes AF cell apoptosis and suppresses AF matrix synthesis compared with low mechanical tension. The present study indirectly indicates how mechanical overload induces disc degeneration through affecting AF biology.

scholarly journals Melatonin Inhibits Annulus Fibrosus Cell Senescence through Regulating the ROS/NF-κB Pathway in an Inflammatory Environment

2021 ◽  
Vol 2021 ◽  
pp. 1-6
Author(s):  
Jing Li ◽  
Jianghua Li ◽  
Chengzhang Cao ◽  
Jianhua Sun ◽  
Sibo Wang ◽  
...  
Keyword(s):  
Disc Degeneration ◽  
Annulus Fibrosus ◽  
Underlying Mechanism ◽  
Telomerase Activity ◽  
Cell Senescence ◽  
Oxygen Species ◽  
Protective Effects ◽  
Tnf Α ◽  
Factor Α ◽  
Necrosis Factor

Inflammation response is an important reason for disc cell senescence during disc degeneration. Recently, melatonin is suggested to protect against disc degeneration. However, the effects of melatonin on annulus fibrosus (AF) cell senescence are not fully studied. The main purpose of this study was to investigate the effects of melatonin on AF cell senescence in an inflammatory environment and the underlying mechanism. Rat disc AF cells were cultured in a medium with tumor necrosis factor-α (TNF-α). Melatonin was added along with the medium to observe its protective effects. Compared with the control AF cells, TNF-α significantly declined cell proliferation potency and telomerase activity, elevated senescence-associated β-galactosidase (SA-β-Gal) activity, upregulated protein expression of senescence markers (p16 and p53), and increased reactive oxygen species (ROS) content and activity of the NF-κB pathway. However, when the TNF-α-treated AF cells were incubated with melatonin, ROS content and activity of the NF-κB pathway were decreased, and those parameters reflecting cell senescence indicated that AF cell senescence was also partly alleviated. Together, melatonin suppresses AF cell senescence through regulating the ROS/NF-κB pathway in an inflammatory environment. This study sheds a new light that melatonin may be promising to retard inflammation-caused disc degeneration.

scholarly journals Resveratrol attenuates inflammation environment-induced nucleus pulposus cell senescence in vitro

2019 ◽  
Vol 39 (5) ◽  
Author(s):  
Xiaoming Li ◽  
Feixiang Lin ◽  
Yaohong Wu ◽  
Ning Liu ◽  
Jun Wang ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Cell Proliferation ◽  
Protein Expression ◽  
Cell Cycle Arrest ◽  
Inflammatory Cytokine ◽  
Telomerase Activity ◽  
Cell Senescence ◽  
Control Group ◽  
Cycle Arrest ◽  
Inflammation Group

Abstract Intervertebral disc degeneration is a disease identified as an inflammation response-participated pathological process. As a classical cellular feature, disc cell senescence is reported to be closely related with disc cell senescence. Resveratrol has a protective role against inflammation in some cells. However, its biological effects on disc cells remain largely unclear. The present study was aimed to study the effects of resveratrol on disc nucleus pulposus (NP) cell senescence in an inflammation environment. Isolated NP cells were cultured in cultured medium with (control group) or without (inflammation group) inflammatory cytokine TNF-α and IL-1β for 14 days. Resveratrol was added along with the NP cells treated with inflammatory cytokines to investigate its effects. NP cell senescence was analyzed by senescence-associated β-Galactosidase (SA-β-Gal) staining, cell proliferation, G0/1 cell cycle arrest, telomerase activity, gene/protein expression of senescence markers (p16 and p53) and NP matrix biosynthesis. In addition, the intracellular reactive oxygen species (ROS) was also analyzed. Compared with the control group, inflammation group significantly increased SA-β-Gal activity and ROS content, decreased cell proliferation and telomerase activity, promoted G0/1 cell cycle arrest, up-regulated gene/protein expression of senescence markers (p16 and p53) and matrix catabolism enzymes (MMP-3, MMP-13 and ADAMTS-4), and down-regulated gene/protein expression of NP matrix macromolecules (aggrecan and collagen II). However, resveratrol partly reversed the effects of inflammatory cytokine on these cell senescence-associated parameters. Together, resveratrol was effective to suppress cell senescence in an inflammatory environment. The present study shows new knowledge on how to retard inflammation response-initiated disc degeneration.

scholarly journals Hyper-osmolarity environment-induced oxidative stress injury promotes nucleus pulposus cell senescence in vitro

2019 ◽  
Vol 39 (9) ◽  
Author(s):  
Jiawei Xu ◽  
Haopeng Li ◽  
Kai Yang ◽  
Shuai Guo ◽  
Jie Wang ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Cell Proliferation ◽  
Nucleus Pulposus ◽  
Disc Degeneration ◽  
Telomerase Activity ◽  
Cell Senescence ◽  
Stress Injury ◽  
Regulated Expression ◽  
Collagen Ii

Abstract Nucleus pulposus (NP) cell senescence is involved in disc degeneration. The in situ osmolarity within the NP region is an important regulator of disc cell’s biology. However, its effects on NP cell senescence remain unclear. The present study was aimed to investigate the effects and mechanism of hyper-osmolarity on NP cell senescence. Rat NP cells were cultured in the in situ-osmolarity medium and hyper-osmolarity medium. The reactive oxygen species (ROS) scavenger N-acetylcysteine (NAC) was added along with the medium to investigate the role of oxidative injury. Cell cycle, cell proliferation, senescence associated β-galactosidase (SA-β-Gal) activity, telomerase activity, expression of senescence markers (p16 and p53) and matrix molecules (aggrecan and collagen II) were tested to assess NP cell senescence. Compared with the in situ-osmolarity culture, hyper-osmolarity culture significantly decreased cell proliferation and telomerase activity, increased SA-β-Gal activity and cell fraction in the G0/G1 phase, up-regulated expression of senescence markers (p16 and p53) and down-regulated expression of matrix molecules (aggrecan and collagen II), and increased intracellular ROS accumulation. However, addition of NAC partly reversed these effects of hyper-osmolarity culture on cellular senescence and decreased ROS content in NP cells. In conclusion, a hyper-osmolarity culture promotes NP cell senescence through inducing oxidative stress injury. The present study provides new knowledge on NP cell senescence and helps us to better understand the mechanism of disc degeneration.

scholarly journals Toll-like receptor 2 induced senescence in intervertebral disc cells of patients with back pain can be attenuated by o-vanillin

2021 ◽  
Vol 23 (1) ◽  
Author(s):  
Matthew Mannarino ◽  
Hosni Cherif ◽  
Li Li ◽  
Kai Sheng ◽  
Oded Rabau ◽  
...  
Keyword(s):  
Gene Expression ◽  
Back Pain ◽  
Protein Expression ◽  
Disc Degeneration ◽  
Cell Senescence ◽  
Enzyme Linked Immunosorbent Assay ◽  
Matrix Synthesis ◽  
Gene And Protein Expression ◽  
Pain Patients ◽  
In Cells

Abstract Background There is an increased level of senescent cells and toll-like teceptor-1, -2, -4, and -6 (TLR) expression in degenerating intervertebral discs (IVDs) from back pain patients. However, it is currently not known if the increase in expression of TLRs is related to the senescent cells or if it is a more general increase on all cells. It is also not known if TLR activation in IVD cells will induce cell senescence. Methods Cells from non-degenerate human IVD were obtained from spine donors and cells from degenerate IVDs came from patients undergoing surgery for low back pain. Gene expression of TLR-1,2,4,6, senescence and senescence-associated secretory phenotype (SASP) markers was evaluated by RT-qPCR in isolated cells. Matrix synthesis was verified with safranin-O staining and Dimethyl-Methylene Blue Assay (DMMB) confirmed proteoglycan content. Protein expression of p16INK4a, SASP factors, and TLR-2 was evaluated by immunocytochemistry (ICC) and/or by enzyme-linked immunosorbent assay (ELISA). Results An increase in senescent cells was found following 48-h induction with a TLR-2/6 agonist in cells from both non-degenerate and degenerating human IVDs. Higher levels of SASP factors, TLR-2 gene expression, and protein expression were found following 48-h induction with TLR-2/6 agonist. Treatment with o-vanillin reduced the number of senescent cells, and increased matrix synthesis in IVD cells from back pain patients. Treatment with o-vanillin after induction with TLR-2/6 agonist reduced gene and protein expression of SASP factors and TLR-2. Co-localized staining of p16INK4a and TLR-2 demonstrated that senescent cells have a high TLR-2 expression. Conclusions Taken together our data demonstrate that activation of TLR-2/6 induce senescence and increase TLR-2 and SASP expression in cells from non-degenerate IVDs of organ donors without degeneration and back pain and in cells from degenerating human IVD of patients with disc degeneration and back pain. The senescent cells showed high TLR-2 expression suggesting a link between TLR activation and cell senescence in human IVD cells. The reduction in senescence, SASP, and TLR-2 expression suggest o-vanillin as a potential disease-modifying drug for patients with disc degeneration and back pain.

scholarly journals N-Cadherin Attenuates High Glucose-Induced Nucleus Pulposus Cell Senescence Through Regulation of the ROS/NF-κB Pathway

2018 ◽  
Vol 47 (1) ◽  
pp. 257-265 ◽  
Author(s):  
Gang Hou ◽  
Huiqing Zhao ◽  
Haijun Teng ◽  
Pei Li ◽  
Wenbin Xu ◽  
...  
Keyword(s):  
Cell Proliferation ◽  
Nucleus Pulposus ◽  
Western Blotting ◽  
High Glucose ◽  
Culture Medium ◽  
Telomerase Activity ◽  
Cell Senescence ◽  
Cell Phenotype ◽  
P53 Expression ◽  
Pathway Activity

Background/Aims: Diabetes mellitus (DM) is a potential etiology of disc degeneration. N-cadherin (N-CDH) helps maintain the cell viability, cell phenotype and matrix biosynthesis of nucleus pulposus (NP) cells. Here, we mainly aimed to investigate whether N-CDH can attenuate high glucose-induced NP cell senescence and its potential mechanism. Methods: Rat NP cells were cultured in a base culture medium and base culture medium with a 0.2 M glucose concentration. Recombinant lentiviral vectors were used to enhance N-CDH expression in NP cells. Senescence-associated β-galactosidase (SA-β-Gal) activity was measured by SA-β-Gal staining. NP cell proliferation was evaluated by CCK-8 assay. Telomerase activity and intracellular reactive oxygen species (ROS) content were tested by specific chemical kits according to the manufacturer’s instructions. G0/G1 cell cycle arrest was evaluated by flow cytometry. Real-time PCR and Western blotting were used to analyze mRNA and protein expressions of senescence markers (p16 and p53) and matrix macromolecules (aggrecan and collagen II). Additionally, p-NF-κB expression was also analyzed by Western blotting to evaluate NF-κB pathway activity. Results: High glucose significantly decreased N-CDH expression, increased ROS generation and NF-κB pathway activity, and promoted NP cell senescence, which was reflected in the increase in SA-β-Gal activity and senescence marker (p16 and p53) expression, compared to the control group. High glucose decreased telomerase activity and cell proliferation potency. However, N-CDH overexpression partially attenuated NP cell senescence, decreased ROS content and inhibited the activation of the NF-κB pathway under the high glucose condition. Conclusion: High glucose decreases N-CDH expression and promotes NP cell senescence. N-CDH overexpression can attenuate high glucose-induced NP cell senescence through the regulation of the ROS/ NF-κB pathway. This study suggests that N-CDH is a potential therapeutic target to slow DM-mediated disc NP degeneration.

Mesenchymal stem cells promote caspase expression in Molt-4 leukemia cells via GSK-3α/β and ERK1/2 signaling pathways as a therapeutic strategy

2020 ◽  
Vol 20 ◽  
Author(s):  
Ezzatollah Fathi ◽  
Ilja Vietor
Keyword(s):  
Stem Cells ◽  
Mesenchymal Stem Cells ◽  
Protein Expression ◽  
Signaling Pathways ◽  
Lymphoblastic Leukemia ◽  
Telomerase Activity ◽  
Cell Senescence ◽  
Activity Measurement ◽  
Caspase 8 ◽  
Expression Levels

Background: Mesenchymal stem cells (MSCs) are considered an interesting tool in cell therapy due to their unique features such as self-renewal, multi-potency, and pluripotency. The multifunctional properties of these cells are being investigated in many studies. The current research examined the influence of MSCs on the Molt-4 cell line as acute lymphoblastic leukemia (ALL) cells. Methods: MSCs were cultured, characterized, and co-cultured with Molt-4 cells in a trans-well system. Then, cultured Molt4 alone and Molt-4 co-cultured with MSCs (10:1) were collected on day 7 and subjected to western blotting for protein expression assessment. Telomerase activity as well as cell senescence were investigated by PCR-ELISA TRAP assay and βgalactosidase activity measurement, respectively. Results: It was found that MSCs resulted in a significant increase in the pro-caspase-8 and cleaved-caspase 8 and 9 expression levels. Furthermore, protein expression levels of GSK-3α/β and ERK1/2 were significantly decreased. The results also showed that MSCs caused significant decreases and increases in telomerase and β-galactosidase enzyme activity of Molt-4 cells, respectively. Conclusions: It was concluded that MSCs co-cultured with Molt-4 cells could be involved in the promotion of Molt-4 cell apoptosis and cell senescence via caspase-8, 9 cascade and GSK-3α/β and ERK1/2 signaling pathways.

scholarly journals Protein kinase D1 phosphorylates CBX8 to facilitate the disassociation of PRC1 complex from p16 promoter and promotes cell senescence

2020 ◽  
Author(s):  
Yuanyuan Su ◽  
Yao Liang ◽  
Chenzhong Xu ◽  
Na Zhang ◽  
Doudou Liu ◽  
...  
Keyword(s):  
Cell Proliferation ◽  
Protein Kinase ◽  
Cell Biology ◽  
Hepatocellular Cancer ◽  
Cell Senescence ◽  
Polycomb Group ◽  
Republic Of China ◽  
Protein Kinase D1 ◽  
Serum Stimulation ◽  
And Migration

AbstractThe Polycomb group (PcG) protein chromobox 8 (CBX8) is the subunit of Polycomb repressive complex 1 (PRC1) and recognizes the trimethylation of histone H3 on Lysine 27 (H3K27me3), and coordinates with PRC2 complex to function as epigenetic gene silencer. CBX8 plays a key role in cell proliferation, stem cell biology, cell senescence, and cancer development. However, our knowledge of CBX8 post-translational modifications remains elusive. Here, we report that protein kinase D1 (PKD1) interacts and phosphorylates CBX8 at Ser256 and Ser311 in an evolutionarily conserved motif. We found that PKD1 activation triggered by serum stimulation, Nocodazole treatment and oncogene Ras-induced cell senescence (Ras OIS) all promotes CBX8 S256/311 phosphorylation. PKD1-mediated CBX8 S256/311 phosphorylation impairs PRC1 complex integrity by reducing the binding of CBX8 to other PRC1 components BMI1 and RING1B, decreases the monoubiquitination of histone H2AK119, and results in CBX8 dissociation from its target INK4a/ARF locus and the de-repression of p16, and thus ultimately facilitates cellular senescence. CBX8 S256/311 phosphorylation also compromises hepatocellular cancer cells proliferation and migration. Collectively, these results suggest that PKD1-mediated CBX8 S256/311 phosphorylation is a key mechanism governing CBX8 function, including cell senescence and cancer cell proliferation.Financial supportThis work was supported by grants from Ministry of Science and Technology of the People’s Republic of China (2018YFC2000102), and from National Natural Science Foundation of China (31871382 and 81571369).

scholarly journals HnRNP F/H associate with hTERC and telomerase holoenzyme to modulate telomerase function and promote cell proliferation

2019 ◽  
Vol 27 (6) ◽  
pp. 1998-2013 ◽  
Author(s):  
Chenzhong Xu ◽  
Nan Xie ◽  
Yuanyuan Su ◽  
Zhaomeng Sun ◽  
Yao Liang ◽  
...  
Keyword(s):  
Cell Proliferation ◽  
Stem Cell ◽  
Telomerase Activity ◽  
Cell Senescence ◽  
Promote Cell Proliferation ◽  
Associated Proteins ◽  
Hnrnp F ◽  
Human Telomerase

AbstractHuman telomerase RNA component hTERC comprises multiple motifs that contribute to hTERC biogenesis, holoenzyme activity, and enzyme recruitment to telomeres. hTERC contains several guanine tracts (G-tracts) at its 5′-end, but its associated proteins and potential roles in telomerase function are still poorly understood. The heterogeneous nuclear ribonucleoproteins F, H1, and H2 (hnRNP F/H) are splicing factors that preferentially bind to poly(G)-rich sequences RNA. Here, we demonstrate that hnRNP F/H associate with both hTERC and telomerase holoenzyme to regulate telomerase activity. We reveal hnRNP F/H bind to the 5′-end region of hTERC in vitro and in vivo, and identify the first three G-tracts of hTERC and qRRM1 domain of hnRNP F/H are required for their interaction. Furthermore, hnRNP F/H also directly interact with telomerase holoenzyme. Functionally, we show that hnRNP F/H plays important roles in modulating telomerase activity and telomere length. Moreover, hnRNP F/H deletion greatly impair cancer and stem cell proliferation, and induce stem cell senescence, while hnRNP F/H overexpression delay stem cell senescence. Collectively, our findings unveil a novel role of hnRNP F/H as the binding partners of hTERC and telomerase holoenzyme to regulate telomerase function.

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