Taurine stimulates protein synthesis and proliferation of C2C12 myoblast cells through the PI3K-ARID4B-mTOR pathway

2021 ◽  
pp. 1-27
Author(s):  
Qi Hao ◽  
Lulu Wang ◽  
Minghui Zhang ◽  
Zhe Wang ◽  
Meng Li ◽  
...  

Abstract Taurine (Tau) has many profound physiological functions, but its role and molecular mechanism in muscle cells are still not fully understood. In this study, we investigated the role and underlying molecular mechanism of Tau on protein synthesis and proliferation of C2C12 myoblast cells. Cells were treated with Tau (0, 60, 120, 180 and 240 μM) for 24 h. Tau dose-dependently promoted protein synthesis, cell proliferation, mTOR phosphorylation, and also AT-rich interaction domain 4B (ARID4B) expression, with the best stimulatory effects at 120 μM. LY 294002 treatment showed that Tau promoted ARID4B expression in a PI3K-dependent manner. ARID4B knockdown (by siRNA transfection for 24 h) prevented Tau from stimulating protein synthesis and cell proliferation, whereas ARID4B gene activation (using the CRISPR/dCas9 technology) had stimulatory effects. ARID4B knockdown abolished Tau signaling to mRNA expression and protein phosphorylation of mTOR, whereas ARID4B gene activation had stimulatory effects. ChIP-PCR identified that all of ARID4B, H3K27ac and H3K27me3 bound to the -4368∼-4591 bp site in the mTOR promoter, and ChIP-qPCR further detected that Tau stimulated ARID4B binding to this site. ARID4B knockdown or gene activation did not affect H3K27me3 binding to the mTOR promoter, but decreased or increased H3K27ac binding, respectively. Furthermore, ARID4B knockdown abolished the stimulation of Tau on H3K27ac binding to the mTOR promoter. In summary, these data uncover that Tau promotes protein synthesis and proliferation of C2C12 myoblast cells through the PI3K-ARID4B-mTOR pathway, providing a deep understanding how Tau regulates anabolism in muscle cells.

2020 ◽  
Vol 19 ◽  
pp. 153303382095702
Author(s):  
Xue-zhen Song ◽  
Xiao-ning Ren ◽  
Xiao-jun Xu ◽  
Xiao-xuan Ruan ◽  
Yi-li Wang ◽  
...  

Hepatocellular carcinoma (HCC) is a severe disease with high mortality in the world. Emerging evidence has suggested that lncRNAs play an important role in cancer progression, including HCC. This study aimed to comprehensively investigate the effect of lncRNA RHPN1 antisense RNA 1 (RHPN1-AS1) on HCC and its underlying molecular mechanism. In this study, we evaluated the expressions of lncRNA RHPN1-AS1 and miR-7-5p by qRT-RCR in both HCC tissue and HCC cells. Our findings showed that lncRNA RHPN1-AS1 was upregulated in HCC tissue and HCC cells, while miR-7-5p was downregulated. LncRNA RHPN1-AS1 expression in HCC patients was closely related to vascular invasion, tumor-node-metastasis (TNM) stage and barcelona clinic liver cancer (BCLC) stage. Furthermore, we quantified cell clone-formation ability, proliferation, migration and invasion of HCCLM3 and MHCC97 H cells using several assays (colony formation assay, 5-Ethynyl-2′-deoxyuridine (EdU) assay and transwell assay, respectively). Functional experiments confirmed that silencing lncRNA RHPN1-AS1 inhibited cell proliferation, migration and invasion in HCCLM3 and MHCC97 H cells. After that, bioinformatics analysis, dual luciferase reporter gene assay, qRT-PCR and western blot were used to investigate the molecular mechanism of lncRNA RHPN1-AS1 on HCC. Mechanistically, the rescue experiments demonstrated that miR-7-5p inhibitor reversed the inhibition effect of silencing lncRNA RHPN1-AS1 on HCCLM3 cells proliferation, migration and invasion. Moreover, silencing lncRNA RHPN1-AS1 also inhibited the activation of PI3K/AKT/mTOR pathway. Taken together our findings demonstrated that lncRNA RHPN1-AS1 could facilitate cell proliferation, migration and invasion via targeting miR-7-5p and activating PI3K/AKT/mTOR pathway in HCC.


2017 ◽  
Vol 43 (3) ◽  
pp. 1100-1112 ◽  
Author(s):  
Suifeng Liu ◽  
Feng Gao ◽  
Lei Wen ◽  
Min Ouyang ◽  
Yi Wang ◽  
...  

Background/Aims: Sarcopenia is characterized by an age-related decline in skeletal muscle plus low muscle strength and/or physical performance. Despite the clinical significance of sarcopenia, the molecular pathways underlying sarcopenia remain elusive. The recent demonstration that undercarboxylated osteocalcin (ucOC) favours muscle function related to insulin sensitivity and glucose metabolism raises the question of whether this hormone may also regulate muscle mass. The present study explored the promotive effects of ucOC in proliferation and differentiation processes of C2C12 myoblasts as well as the possible signalling pathways involved. Methods: The effects of exogenous ucOC on C2C12 myoblasts proliferation were assessed using CCK8 and immunohistological staining assays. C2C12 cells were pretreated with PI3K/Akt or P38 MAPK inhibitors to investigate the possible involvement of the PI3K/Akt and P38 MAPK pathways in proliferation. The levels of Akt, phosphorylated-Akt (p-Akt), P38, and phosphorylated-P38 (p-P38) were measured by Western Blotting. The effects of ucOC on myoblast differentiation were quantified by morphological analysis. A silencing experiment was conducted in which the expression of GPRC6A in C2C12 myoblasts was modified. The expression of GPRC6A, myosin heavy chain (MyHC) and the related ERK1/2 signalling pathway in C2C12 myoblasts were monitored by qRT-PCR and Western Blotting. Results: We showed that treatment with exogenous ucOC stimulated the priming of C2C12 myoblasts proliferation. Inhibition of Akt phosphorylation by wortmannin or inhibition of P38 MAPK phosphorylation by SB203580 decreased C2C12 cell proliferation. Wortmannin also reduced P38 MAPK phosphorylation, whereas SB203580 did not affect Akt activation. Furthermore, ucOC promoted C2C12 myoblast differentiation. Inhibition of ERK1/2 phosphorylation with U0126 decreased C2C12 cell differentiation. Finally, GPRC6A expression was substantially increased after ucOC treatment of C2C12 cells. GPRC6A silencing inhibited Akt, P38 MAPK phosphorylation in C2C12 cells, and ERK1/2 phosphorylation in C2C12 myotubes; GPRC6A silencing also decreased cell proliferation, decreased cell differentiation, and downregulated MyHC expression. Conclusions: The present data suggest that ucOC induces myoblast proliferation via sequential activation of the PI3K/Akt and p38 MAPK pathways in C2C12 myoblast cells. Moreover, ucOC enhances myogenic differentiation via a mechanism involving GPRC6A-ERK1/2 signalling.


1998 ◽  
Vol 275 (4) ◽  
pp. H1209-H1215 ◽  
Author(s):  
Peter A. Wilden ◽  
Yehenew M. Agazie ◽  
Rebecca Kaufman ◽  
Stephen P. Halenda

Vascular smooth muscle cells respond to the purinergic agonist ATP by increasing intracellular calcium concentration and increasing the rate of cell proliferation. In many cells the extracellular signal-regulated kinase (ERK) cascade plays an important role in cellular proliferation. We have studied the effect of extracellular ATP on ERK activation and cell proliferation. ATP binding to a UTP-sensitive P2Y nucleotide receptor activates ERK1/ERK2 in a time- and dose-dependent manner in coronary artery smooth muscle cells (CASMC). ATP-induced activation of ERK1/ERK2 is dependent on the dual-specificity kinase mitogen-activated protein kinase/ERK kinase (i.e., MEK) but independent of phosphatidylinositol 3-kinase (PI3K) activity. We provide evidence that both ERK1/ERK2 and PI3K activities are required for CASMC proliferation. Thus ATP-stimulation of CASMC proliferation requires independent activation of both the ERK and PI3K signaling pathways.


2008 ◽  
Vol 41 (5) ◽  
pp. 389-392 ◽  
Author(s):  
Aspasia-Athina Volakaki ◽  
Daniel Lafkas ◽  
Eva Kassi ◽  
Andrew V Schally ◽  
Athanasios G Papavassiliou ◽  
...  

GHRH, besides its neuroendocrine action in controlling the release of GH from the pituitary, stimulates the growth of various cancers in vivo and in vitro by direct mechanism(s). However, the molecular mechanism that mediates these proliferative effects of GHRH in extrapituitary tissues remains poorly characterized. In the present study, we investigated whether the tumor suppressor p21/waf1 is involved in the mediation of the proliferative effects of GHRH in A549 human lung cancer epithelial cells. Exposure of A549 cells to the GHRH antagonist JMR-132 caused a significant inhibition in the rate of cell proliferation. In A549 cells, GHRH suppressed while JMR-132 increased the levels of p21 expression in a dose-dependent manner. This suggests that GHRH could regulate p21 levels. We then evaluated whether p21 is required in A549 cells for the regulation of cell proliferation by GHRH. To this end, we knocked-down p21 expression in A549 cells by siRNA and assessed the effects of antagonist JMR-132 on cell proliferation. We found that the loss of p21 expression abolished the anti-proliferative effects of JMR-132. Suppression of p21 expression by siRNA in human HT29 colon cancer cells and non-transformed mouse osteoblasts KS483 also blocked the anti-proliferative effects of JMR-132 suggesting that the regulation of cell proliferation by GHRH is p21 dependent. These results shed light on the molecular mechanism of action of GHRH antagonists in tumor tissues and suggest that the antineoplastic activity of GHRH antagonists could be considered for the treatment of cancers expressing p21.


2000 ◽  
Vol 275 (44) ◽  
pp. 34619-34627 ◽  
Author(s):  
Kouichi Tamura ◽  
Yuqing E. Chen ◽  
Marco Lopez-Ilasaca ◽  
Laurent Daviet ◽  
Nobuko Tamura ◽  
...  

2014 ◽  
Vol 53 (3) ◽  
pp. 331-343 ◽  
Author(s):  
Ana P Irazoqui ◽  
Ricardo L Boland ◽  
Claudia G Buitrago

Previously, we have reported that 1,25(OH)2-vitamin D3(1,25D) activates p38 MAPK (p38) in a vitamin D receptor (VDR)-dependent manner in proliferative C2C12 myoblast cells. It was also demonstrated that 1,25D promotes muscle cell proliferation and differentiation. However, we did not study these hormone actions in depth. In this study we have investigated whether the VDR and p38 participate in the signaling mechanism triggered by 1,25D. In C2C12 cells, the VDR was knocked down by a shRNA, and p38 was specifically inhibited using SB-203580. Results from cell cycle studies indicated that hormone stimulation prompts a peak of S-phase followed by an arrest in the G0/G1-phase, events which were dependent on VDR and p38. Moreover, 1,25D increases the expression of cyclin D3 and the cyclin-dependent kinase inhibitors, p21Waf1/Cip1and p27Kip1, while cyclin D1 protein levels did not change during G0/G1 arrest. In all these events, p38 and VDR were required. At the same time, a 1,25D-dependent acute increase in myogenin expression was observed, indicating that the G0/G1 arrest of cells is a pro-differentiative event. Immunocytochemical assays revealed co-localization of VDR and cyclin D3, promoted by 1,25D in a p38-dependent manner. When cyclin D3 expression was silenced, VDR and myogenin levels were downregulated, indicating that cyclin D3 was required for 1,25D-induced VDR expression and the concomitant entrance into the differentiation process. In conclusion, the VDR and p38 are involved in control of the cellular cycle by 1,25D in skeletal muscle cells, providing key information on the mechanisms underlying hormone regulation of myogenesis.


2010 ◽  
Vol 104 (3) ◽  
pp. 326-335 ◽  
Author(s):  
Ming-Jyh Sheu ◽  
Hsu-Chen Cheng ◽  
Yi-Chung Chien ◽  
Pei-Yu Chou ◽  
Guang-Jhong Huang ◽  
...  

The pathological mechanism of restenosis is primarily attributed to excessive proliferation of vascular smooth muscle cells (VSMC). The preventive effects of ethanol extract of Dunaliella salina (EDS) on balloon injury-induced neointimal formation were investigated. To explore its molecular mechanism in regulating cell proliferation, we first showed that EDS markedly reduced the human aortic smooth muscle cell proliferation via the inhibition of 5′-bromo-2′-deoxyuridine (BrdU) incorporation at 40 and 80 μg/ml. This was further supported by the G0/G1-phase arrest using a flow cytometric analysis. In an in vivo study, EDS at 40 and 80 μg/ml was previously administered to the Sprague–Dawley rats and found that the thickness of neointima, and the ratio of neointima:media were also reduced. EDS inhibited VSMC proliferation in a dose-dependent manner following stimulation of VSMC cultures with 15 % fetal bovine serum (FBS). Suppressed by EDS were 15 % FBS-stimulated intracellular Raf, phosphorylated extracellular signal-regulated kinases (p-Erk) involved in cell-cycle arrest and proliferating cell nuclear antigen. Phosphorylated focal adhesion kinase (p-FAK) was also suppressed by EDS. Also active caspase-9, caspase-3 and cleaved poly(ADP-ribose) polymerase (PARP) protein expression levels were increased by administration with EDS; the apoptotic pathway may play an important role in the regulatory effects of EDS on cell growth. These observations provide a mechanism of EDS in attenuating cell proliferation, thus as a potential intervention for restenosis.


Blood ◽  
2015 ◽  
Vol 126 (23) ◽  
pp. 2435-2435
Author(s):  
Akihiko Yokoyama ◽  
Hiroshi Okuda

Abstract Chromosomal translocations generate a variety of mixed lineage leukemia (MLL) fusion genes, which cause aggressive leukemia. Although >70 different fusion partners have been identified, the majority of the cases are caused by the chimeric genes of MLL and a component of the AEP co-activator complex (hereafter referred to as AEP), which comprises of AF4 family proteins (e.g. AF4, AF5Q31), ENL family proteins (e.g. ENL, AF9), and the P-TEFb elongation factor. MLL-AEP fusion proteins constitutively activate their target genes by recruiting AEP components to their target chromatin, whereas wild-type MLL recruits AEP in a context-dependent manner. In the hematopoietic lineage, MLL fusion proteins aberrantly activate a subset of genes implicated in the hematopoietic stem cell (HSC) program, such as HOXA9 and MEIS1. Constitutive expression of these HSC program genes in hematopoietic progenitors has been shown to induce leukemia in a mouse model. It has been speculated that MLL-AEP activates transcription of those HSC program genes by aberrantly activating transcription elongation. However, it is largely unclear how AEP activates transcription. Using an extensive structure/function analysis, we revealed that a serine-rich domain of the AF4 family proteins, termed pSER, is an essential functional component of MLL-AEP-dependent gene activation and leukemic transformation. Through biochemical purification, we have identified Selectivity Factor 1 (SL1) as a novel factor associated with the pSER domain. SL1 comprises TBP and four TBP-associated factors (TAF1A, TAF1B, TAF1C, TAF1D), and is known as a core component of the pre-initiation complex (PIC) of RNA polymerase I (RNAP1). In the presence of UBF, SL1 forms a PIC on the promoters of ribosomal RNA genes, to drive RNAP1-dependent transcription. However, its role in RNAP2-dependent transcription was unknown. The initiation of RNAP2-dependent transcription in eukaryotes occurs through the loading of TBP to the promoter, via a direct association with the TATA element or through as-yet-unidentified mechanisms. Our results demonstrate that AEP facilitates the initiation of RNAP2-dependent transcription via the loading of TBP onto the TATA element, through SL1 activity. MLL-AEP fusion proteins utilize this TBP-loading function to activate transcription initiation in leukemic transformation. The wild-type AEP complex activates gene expression in the same manner in the physiological conditions. Taken together, our results unveil a novel role of SL1 as a TBP-loading factor in RNAP2-dependent gene activation, and a previously unknown transcription initiation mechanism involving AEP, which is more important than its transcription elongation activities for leukemic transformation. These findings greatly advance our understanding of the molecular mechanism of MLL fusion-dependent leukemic transformation, which was previously interpreted simply as mis-regulated transcription elongation. Disclosures Yokoyama: Dainipon Sumitomo Pharma Co., Ltd.: Research Funding.


2019 ◽  
Vol 2019 ◽  
pp. 1-6
Author(s):  
Xiuxia Wang ◽  
Yinmin Wang ◽  
Xianyu Zhou ◽  
Fei Liu

Background. Since the first report on the immunomodulatory and immunosuppressive properties of Adipose-Derived Stem Cells (ADSCs), many studies have elucidated the underlying molecular mechanism of their suppressive activity on mixed lymphocyte reaction (MLR). However, a gap exists in our understanding of the molecular mechanism of ADSC-conditioned medium (ADSC-CM) on MLR. Methods. ADSCs were isolated from Human Adipose Tissues, and Enzyme-linked Immunosorbent Assay (ELISA) was used to identify the concentration of transforming growth factor β1 (TGF-β1) in ADSC-CM. The transcript abundance of TGF-β1, as well as that of insulin-like growth factor binding protein 3 (IGF-BP3), was evaluated using qRT-PCR on Jurkat cells cultured in ADSC-CM for 24 hours. The proliferation of the Jurkat cells was assessed using cell cycle assay. Western blotting was performed to identify potential signaling molecules involved in the ADSC-CM-induced inhibition of Jurkat cell proliferation. Results. The findings confirm that the isolated ADSCs demonstrate classic ADSC characteristics. The level of TGF-β1 was found to be low in ADSC-CM, as assessed by ELISA. Jurkat cells grown in ADSC-CM show reduced gene expression of TGF-β1 and IGF-BP3 compared with that of the control group. Furthermore, western blotting of ADSC-CM grown Jurkat cells that were blocked at the G0/G1 stage indicates that ADSC-CM decreases the protein expression of pP38 in a dose-dependent manner. Conclusion. ADSC-CM can inhibit Jurkat cell proliferation through the TGF-β1-p38 signaling pathway.


1992 ◽  
Vol 262 (3) ◽  
pp. C578-C588 ◽  
Author(s):  
S. P. Bagby ◽  
M. M. O'Reilly ◽  
E. A. Kirk ◽  
L. H. Mitchell ◽  
P. E. Stenberg ◽  
...  

To characterize growth effects of epidermal growth factor (EGF) in subconfluent quiescent porcine aortic vascular smooth muscle cells (VSMC), we measured DNA and protein synthesis by [3H]thymidine (Thd) and [35S]methionine (Met) incorporation, respectively, and cell proliferation rates over 0-6 days in Dulbecco's modified Eagle's-Ham's F-12 media containing 0.4% fetal calf serum (FCS) and insulin. EGF induced dose-dependent [3H]Thd uptake (P less than 0.001); after 10(-9) M EGF, DNA synthesis rate peaked at 24 h, averaging 77% of the response to 10% FCS, and then declined steeply with nadir at 48-60 h. Unexpectedly, EGF failed to induce cell proliferation in the first 4 days, leaving this initial burst of DNA synthesis (12-60 h) uncoupled from cell division. A second lesser but sustained phase of increased DNA synthesis, apparent by day 3-4, was associated with a small increase in cell number on day 6 (P less than 0.05). The early unsustained burst of DNA synthesis reflects EGF's potent mitogenic efficacy for DNA synthesis (G1- to S-phase traversal), probably acting on a subset of cells partially synchronized initially at an EGF-responsive G0/G1 locus; the minimal cell division despite brisk DNA synthesis documents EGF's limited efficacy for (or inhibition of) late cell-cycle events required for completion of mitosis. Late cell-cycle processes are thus rate limiting. EGF also increased protein synthetic rate over control (P less than 0.03) but to a lesser degree (P less than 0.01) than 10% FCS. Indomethacin (10(-6) M) did not alter DNA or proliferative responses to 10(-9) M EGF but transiently augmented EGF-induced protein synthesis (P less than 0.025) at 24 h only.(ABSTRACT TRUNCATED AT 250 WORDS)


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