Commenced in January 2007
Frequency: Monthly
Edition: International
Paper Count: 5

Sirt1 Related Abstracts

5 Sirt1 Promotes C2C12 Myoblast Cell Proliferation by Myostatin Signaling Pathway

Authors: Liang Wang, Chengcao Sun, Cuili Yang, Ruilin Xue, Yongyong Xi, Dejia Li


Backgrounds: Previous studies showed that Sirt1 plays an important role in C2C12 myoblast cell proliferation, but the mechanism(s) involved in this process remains unclear. This work was undertaken to determine if Myostatin participates in the regulation of C2C12 proliferation by Sirt1. Methods: We administrated the Sirt1 activator resveratrol, inhibitor Nicotinamide (NAM) and Myostatin inhibitor SB431542 on C2C12 myoblast cells. Cell viability was evaluated by CCK8 assay. The expression of Sirt1 and MyoD were detected by qRT-PCR. Utilizing western blot to determinate the expression of myostatin, P107 and p-P107. Results: Our results showed that resveratrol promoted the proliferation of C2C12 myoblast cells, while NAM suppressed the proliferation of C2C12 myoblast cells; SB431542 promoted the proliferation of C2C12 myoblast cells and attenuated the inhibition effect of NAM on C2C12 myoblast cells proliferation; Resveratrol can significantly increase the expression of Sirt1 and MyoD, decrease the expression of Myostatin, while NAM can significantly down-regulate the expression of Sirt1, MyoD and the phosphorylation of P107(p-P107), but up-regulate the expression of Myostatin and the protein P107; SB431542 can significantly mitigate the effect of NAM on the expression of MyoD, P107, and p-P107. Conclusions: Taken together, these results indicate that Sirt1 promotes the proliferation of C2C12 myoblast cells via Myostatin signaling pathway.

Keywords: proliferation, Sirt1, C2C12 cells, myostatin signaling pathway

Procedia PDF Downloads 250
4 The Improved Therapeutic Effect of Trans-Cinnamaldehyde on Adipose-Derived Stem Cells without Chemical Induction

Authors: Karthyayani Rajamani, Yi-Chun Lin, Tung-Chou Wen, Jeanne Hsieh, Yi-Maun Subeq, Jen-Wei Liu, Po-Cheng Lin, Horng-Jyh Harn, Shinn-Zong Lin, Tzyy-Wen Chiou


Assuring cell quality is an essential parameter for the success of stem cell therapy, utilization of various components to improve this potential has been the primary goal of stem cell research. The aim of this study was not only to demonstrate the capacity of trans-cinnamaldehyde (TC) to reverse stress-induced senescence but also improve the therapeutic abilities of stem cells. Because of the availability and the promising application potential in regenerative medicine, adipose-derived stem cells (ADSCs) were chosen for the study. We found that H2O2 treatment resulted in the expression of senescence characteristics in the ADSCs, including decreased proliferation rate, increased senescence-associated- β-galactosidase (SA-β-gal) activity, decreased SIRT1 (silent mating type information regulation 2 homologs) expression and decreased telomerase activity. However, TC treatment was sufficient to rescue or reduce the effects of H2O2 induction, ultimately leading to an increased proliferation rate, a decrease in the percentage of SA-β-gal positive cells, upregulation of SIRT1 expression, and increased telomerase activity of the senescent ADSCs at the cellular level. Further recently it was observed that the ADSCs were treated with TC without induction of senescence, all the before said positives were observed. Moreover, a chemically induced liver fibrosis animal model was used to evaluate the functionality of these rescued cells in vivo. Liver dysfunction was established by injecting 200 mg/kg thioacetamide (TAA) intraperitoneally into Wistar rats every third day for 60 days. The experimental rats were separated into groups; normal group (rats without TAA induction), sham group (without ADSC transplantation), positive control group (transplanted with normal ADSCs); H2O2 group (transplanted with H2O2 -induced senescent ADSCs), H2O2+TC group (transplanted with ADSCs pretreated with H2O2 and then further treated with TC) and TC group (ADSC treated with TC without H2O2 treatment). In the transplantation group, 1 × 106 human ADSCs were introduced into each rat via direct liver injection. Based on the biochemical analysis and immunohistochemical staining results, it was determined that the therapeutic effects on liver fibrosis by the induced senescent ADSCs (H2O2 group) were not as significant as those exerted by the normal ADSCs (the positive control group). However, the H2O2+TC group showed significant reversal of liver damage when compared to the H2O2 group 1 week post-transplantation. Further ADSCs without H2O2 treatment but with just TC treatment performed much better than all the groups. These data confirmed that the TC treatment had the potential to improve the therapeutic effect of ADSCs. It is therefore suggested that TC has potential applications in maintaining stem cell quality and could possibly aid in the treatment of senescence-related disorders.

Keywords: Liver Fibrosis, senescence, Sirt1, adipose derived stem cells

Procedia PDF Downloads 126
3 SIRT1 Gene Polymorphisms and Its Protein Level in Colorectal Cancer

Authors: Olfat Shaker, Miriam Wadie, Reham Ali, Ayman Yosry


Colorectal cancer (CRC) is a major cause of mortality and morbidity and accounts for over 9% of cancer incidence worldwide. Silent information regulator 2 homolog 1 (SIRT1) gene is located in the nucleus and exert its effects via modulation of histone and non-histone targets. They function in the cell via histone deacetylase (HDAC) and/or adenosine diphosphate ribosyl transferase (ADPRT) enzymatic activity. The aim of this work was to study the relationship between SIRT1 polymorphism and its protein level in colorectal cancer patients in comparison to control cases. This study includes 2 groups: thirty healthy subjects (control group) & one hundred CRC patients. All subjects were subjected to: SIRT-1 serum level was measured by ELISA and gene polymorphisms of rs12778366, rs375891 and rs3740051 were detected by real time PCR. For CRC patients clinical data were collected (size, site of tumor as well as its grading, obesity) CRC patients showed high significant increase in the mean level of serum SIRT-1 compared to control group (P<0.001). Mean serum level of SIRT-1 showed high significant increase in patients with tumor size ≥5 compared to the size < 5 cm (P<0.05). In CRC patients, percentage of T allele of rs12778366 was significantly lower than controls, CC genotype and C allele C of rs 375891 were significantly higher than control group. In CRC patients, the CC genotype of rs12778366, was 75% in rectosigmoid and 25% in cecum & ascending colon. According to tumor size, the percentage of CC genotype was 87.5% in tumor size ≥5 cm. Conclusion: serum level of SIRT-1 and T allele, C allele of rs12778366 and rs 375891 respectively can be used as diagnostic markers for CRC patients.

Keywords: Polymorphisms, ELISA, Sirt1, CRC

Procedia PDF Downloads 90
2 The Effect of SIRT1 on NLRP3 (Nucleotide Oligomerization Domain-Like Receptor Family, Pyrin Domain Containing 3) Inflammasome of Osteoarthritis

Authors: So Youn Park, Yi Sle Lee, Ki Whan Hong, Chi Dae Kim


The role of metabolism in the pathogenesis of osteoarthritis is an emerging field. Metabolic alterations may be a role in osteoarthritis (OA) pathogenesis, and these changes influence joint destruction via several cytokine. Especially, in OA patients, levels of IL-1β are elevated in the synovial fluid, synovial membrane, subchondral bone, and cartilage. The IL-1β is activated by NLRP3 inflammasomes, and NLRP3 inflammasomes are cytosolic complexes that drive the production of other inflammatory cytokines, including IL-1β. In this study, we examined that SIRT1 suppresses IL-1β through inhibiting NLRP3 inflammasomes and SIRT1 ameliorates osteoarthritis. OA fibroblasts were isolated from synovium of OA patients. IL-1β and NLRP3 were detected in synovium of OA patients by immunohistochemistry. Lipopolysaccharides (LPS) stimulated the expression of active IL-1β mRNA in OA fibroblasts and combination of LPS, and adenosine triphosphate increased more the expression of active IL-1β in OA fibroblasts. The level of IL-1β was measured by western blot and ELISA assay. NLRP3 inflammasomes complex were measured by western blot. SIRT1 did not inhibit expression of NLRP3 inflammasome. So caspase-1, apoptotic speck-like protein containing a caspase recruitment domain (ASC) and NLRP3 protein were expressed in OA fibroblasts. But SIRT1 suppressed activation of IL-1β by inhibiting activity of caspase-1 via NLRP3 inflammasome in OA fibroblasts under LPS plus ATP stimulation. These results suggest that SIRT1 is a modulator of NLRP3 inflammasomes in OA fibroblasts and ameliorate IL-1β, so expression of SIRT1 in OA fibroblast may be a potential strategy for OA inflammation treatment.

Keywords: Osteoarthritis, Sirt1, inflammasome, IL-1beta

Procedia PDF Downloads 58
1 Sirt1 Activators Promote Skin Cell Regeneration and Cutaneous Wound Healing

Authors: Hussain Mustatab Wahedi, Sun You Kim


Skin acts as a barrier against the harmful environmental factors. Integrity and timely recovery of the skin from injuries and harmful effects of radiations is thus very important. This study aimed to investigate the importance of Sirt1 in the recovery of skin from UVB-induced damage and cutaneous wounds by using natural and synthetic novel Sirt1 activators. Juglone, known as a natural Pin1 inhibitor, and NED416 a novel synthetic Sirt1 activator were checked for their ability to regulate the expression and activity of Sirt1 and hence photo-damage and wound healing in cultured skin cells (NHDF and HaCaT cells) and mouse model by using Sirt1 siRNA knockdown, cell migration assay, GST-Pulldown assay, western blot analysis, tube formation assay, and immunohistochemistry. Interestingly, Sirt1 knockdown inhibited skin cell migration in vitro. Juglone up regulated the expression of Sirt1 in both the cell lines under normal and UVB irradiated conditions, enhanced Sirt1 activity and increased the cell viability by reducing reactive oxygen species synthesis and apoptosis. Juglone promoted wound healing by increasing cell migration and angiogenesis through Cdc42/Rac1/PAK, MAPKs and Smad pathways in skin cells. NED416 upregulated Sirt1 expression in HaCaT and NHDF cells as well as increased Sirt1 activity. NED416 promoted the process of wound healing in early as well as later stages by increasing macrophage recruitment, skin cell migration, and angiogenesis through Cdc42/Rac1 and MAPKs pathways. So, both these compounds activated Sirt1 and promoted the process of wound healing thus pointing towards the possible role of Sirt1 in skin regeneration and wound healing.

Keywords: Wound Healing, Sirt1, skin regeneration, UVB light

Procedia PDF Downloads 61