Research progress on function and molecular mechanism of transcription factor ELK1 of Ets / 中国生物制品学杂志

@#Ets transcription factor ELK 1,a member of the ternary complex factor(TCF) subfamily in the Ets family,is directly downstream signal of MAPK/ERK pathway and is activated by phosphorylation to execute the function of ERK signal.ELK1,which is highly expressed and phosphorylated in stem cells and tumor cells,plays a role in promoting proliferation,inhibiting apoptosis and differentiation in stem cells.In tumor cells,ELK1 has shown to promote proliferation,migration,and inhibit apoptosis.In neural cells,ELK1 is involved in long-term memory,learning,addiction and other functions.In this paper,the research progress on the main structure and basic biological characteristics of ELK1,the function and mechanism of ELK 1 in tumor cells,stem cells and nerve cells are reviewed in order to provide new ideas for the follow-up research.

Long Non-Coding RNA LINC00525 Promotes the Stemness and Chemoresistance of Colorectal Cancer by Targeting miR-507/ELK3 Axis

BACKGROUND AND OBJECTIVES: This study aims to explore the effects of a long non-coding RNA, LINC00525, on colorectal cancer (CRC) and its underlying molecular mechanisms. METHODS: The qPCR, MTT, colony formation, Western blotting, Luciferase reporter and biotin pull-down, shRNA knockdown and DNA fragmentation assays were performed in this study. RESULTS: High expressions of LINC00525 were associated with poor prognosis of CRC patients. LINC00525 knockdown decreased stemness properties and increased sensitivities to oxaliplatin. MiR-507 was a direct target of LINC00525 and overexpression of miR-507 significantly decreased abilities of tumorsphere formation and cell growth. Overexpression of miR-507 resulted in a decrease of expression of cancer stem cell markers and the increase of apoptosis rates. MiR-507 regulated the expression of ELK3. In addition, LINC00525 knockdown decreased the expression of ELK3. Restoration of ELK3 expression abrogated the effects of LINC00525 knockdown. LINC00525 could be served as prognostic marker of CRC. CONCLUSIONS: LINC00525 enhanced stemness properties and increased sensitivities of CRC cells to oxaliplatin by targeting miR-507/ELK3 axis.

ELK-3 interference inhibits the epithelial-mesenchymal transition of human hepatocellular carcinoma cells / 基础医学与临床

Objective To investigate the relationship of ELK-3 and epithelial-mesenchymal transition ( EMT) for ex-ploring its possible mechanism .Methods The human hepatocellular carcinoma cells ( HCC) were divided into small interference RNA transfection group and Ras-ELK-3 pathway inhibitor group .The protein level of ELK-3 target gene EGR-1 E-cadherin ,vimentin and p38 in HCC were determined by Western blot analysis .Results The protein level of ELK-3 and its target gene EGR-1 in treated human hepatocellular carcinoma cells significantly decreased as compared with the negative control group (P<0.01).The protein level of E-cadherin was significantly increased (P<0.01), while vimentin and p38 were decreased in HCC cells with ELK-3 interference (P<0.01).Conclusions ELK-3 in-terference can inhibit the epithelial-mesenchymal transition of HCC cells by down-regulating p38.

Elk-3 Contributes to the Progression of Liver Fibrosis by Regulating the Epithelial-Mesenchymal Transition

BACKGROUND/AIMS: The role of Elk-3 in the epithelial-mesenchymal transition (EMT) during liver fibrogenesis remains unclear. Here, we determined the expression of Elk-3 in in vitro and in vivo models and in human liver fibrotic tissues. We also investigated the molecular relationships among Elk-3, early growth response-1 (Egr-1), and the mitogen activated protein kinases (MAPK) pathway during EMT in hepatocytes. METHODS: We established anin vitro EMT model in which normal mouse hepatocyte cell lines were treated with transforming growth factor (TGF)-β1 and a CCl4-induced liver fibrosis model. Characteristics of EMT were determined by evaluating the expression levels of related markers. The expression of Elk-3 and its target Egr-1 were analyzed using Western blotting. Gene silencing of Elk-3 was performed using an siRNA knockdown system. RESULTS: The expression levels of mesenchymal markers were increased during TGF-β1-induced EMT of hepatocytes. The expression levels of Elk-3 and Egr-1 were significantly (p<0.05) increased during the EMT of hepatocytes, in CCl₄-induced mouse liver fibrotic tissues, and in human liver cirrhotic tissues. Silencing of Elk-3 and inhibition of the Ras-Elk-3 pathway with an inhibitor suppressed the expression of EMT-related markers. Moreover, Elk-3 expression was regulated by p38 MAPK phosphorylation during EMT. CONCLUSIONS: Elk-3 contributes to the progression of liver fibrosis by modulating the EMT via the regulation of Egr-1 under MAPK signaling.

SIRT7, H3K18ac, and ELK4 Immunohistochemical Expression in Hepatocellular Carcinoma

BACKGROUND: SIRT7 is one of the histone deacetylases and is NAD-dependent. It forms a complex with ETS-like transcription factor 4 (ELK4), which deacetylates H3K18ac and works as a transcriptional suppressor. Overexpression of SIRT7 and deacetylation of H3K18ac have been shown to be associated with aggressive clinical behavior in some cancers, including hepatocellular carcinoma (HCC). The present study investigated the immunohistochemical expression of SIRT7, H3K18ac, and ELK4 in hepatocellular carcinoma. METHODS: A total of 278 HCC patients were enrolled in this study. Tissue microarray blocks were made from existing paraffin-embedded blocks. Immunohistochemical expressions of SIRT7, H3K18ac and ELK4 were scored and analyzed. RESULTS: High SIRT7 (p = .034), high H3K18ac (p = .001), and low ELK4 (p = .021) groups were associated with poor outcomes. Age < 65 years (p = .028), tumor size ≥ 5 cm (p = .001), presence of vascular emboli (p = .003), involvement of surgical margin (p = .001), and high American Joint Committee on Cancer stage (III&V) (p < .001) were correlated with worse prognoses. In multivariate analysis, H3K18ac (p = .001) and ELK4 (p = .015) were the significant independent prognostic factors. CONCLUSIONS: High SIRT7 expression with poor overall survival implies that deacetylation of H3K18ac contributes to progression of HCC. High H3K18ac expression with poor prognosis is predicted due to a compensation mechanism. In addition, high ELK4 expression with good prognosis suggests another role of ELK4 as a tumor suppressor beyond SIRT7's helper. In conclusion, we could assume that the H3K18ac deacetylation pathway is influenced by many other factors.

Development of monoclonal antibodies against the abnormal prion protein isoform (PrPres) associated with chronic wasting disease (CWD)

Monoclonal antibodies (mAbs) specific for the abnormal prion protein isoform (PrPres) are indispensable for diagnosing chronic wasting disease (CWD). In this study, eight mAbs were developed by immunizing PrP knockout mice with recombinant elk PrP and an immunogenic PrP peptide. The reactivity of the mAbs to recombinant PrP and the PrP peptide was measured, and their isotypes were subsequently determined. Among them, four mAbs (B85-05, B85-08, B85-12, and B77-75) were shown by Western blotting to recognize proteinase K-treated brain homogenate derived from an elk suffering from CWD.

Influence of chronic fluorosis on expression of phospho-Elk-1 in rat brains / 中国地方病学杂志

Objective To investigate the expression and distribution of the downstream substrate of extracellular regulated protein kinase(ERK1/2) pathway, ternary complex factor phospho-Elk-1, in rat brains with chronic fluorosis, and reveal the mechanism of the impaired learning and memory ability caused by chronic fluorosis. Methods Seventy-two SD rats, weighing 100 - 120 g, were randomly divided into 3 groups, 24 in each group (half male and half female). The rats in control group were fed with tap water (fluoride < 0.5 mg/L); low- and high-dose fluoride groups were fed with tap water with different concentrations of NaF(5.0,50.0 mg/L F-, respectively). After 6 months, body weight was weighed, dental fluorosis was determined by observation and urinary fluoride and bone fluoride were detected by fluorine ion-selective electrode; the learning ability of rats was measured by navigation test of Morris water maze, and memory ability by spatial probe test in Morris water maze; the expression and distribution of phospho-Elk-1 in different brain regions were detected by immunohistochemistry method. Results In low- and high-fluoride groups, the body weight of rat[(449.2 ± 77.1), (312.8 ± 89.7)g] was significantly decreased than that of control [(635.5 ± 76.2 )g, all P< 0.05], the varying degrees of dental fluorosis were observed(x2 = 7.83, P<0.05), urinary fluoride[(2.56 ±0.91),(5.73 ±3.14)mg/L] and bone fluoride[(709.2 ± 37.4) ,(1306.3 ± 102.4) mg/kg] were significantly higher than those in controls[(0.92 ± 0.30)mg/L,(348.5 ± 89.2)mg/kg, all P< 0.05]. The escape latency of low- and high-fluoride groups[ (7.4 ± 4.1), (12.2 ± 5.7)s] was longer than that of control [(4.8 ± 2.7 )s, all P < 0.05] and the escape latency in high-fluoride group was significantly longer than that in other groups (all P < 0.05); in spatial probe test, the time of first crossing platform was longer in rats with fluorosis [(4.18 ± 1.10),(5.89 ± 0.56)s] as compared to control[(1.17 ± 0.75)s, all P< 0.05]. Expressions of phospho-Elk-1 in the hippocampus CA1(167.4 ± 8.3,163.2 ± 9.4), CA2(175.7 ± 5.0,183.3 ± 4.2), CA3(165.2 ± 11.6,162.9 ± 4.4), CA4(168.7± 6.9,169.5 ±5.3), fascia dentate (185.2 ±4.0,193.1 ±6.1) and caudate putamen( 181.4 ± 3.8, 179.8 ± 5.5) in low- and high-fluoride groups were higher than those of controls(142.4 ± 8.1,144.9 ± 8.4,143.6 ± 5.8, 116.8 ± 9.1,140.2 ± 7.8,163.1 ± 13.1, all P< 0.05). Conclusion Chronic fluorosis can cause increased expression of phospho-Elk-1 in the hippocampus and caudate putamen region of rat brains, which might be related to the mechanisms of decreased learning and memory ability of rats overexposed to fluoride.

Effect of Elemene on Transcription Factor ELK1 and Its Target Gene of Human Cervix Cancer Hela Cell / 中国中医药信息杂志

Objective To study the effect of elemene on transcription factor ELK1 and its target gene in human cervix cancer Hela cell. Methods The cell proliferation was assessed by MTT assay. The luciferase activity of transcription factor ELK1 was determined by the Dual-Luciferase Reporter Assay System. The protein expression of phosphorated ELK1 and its target gene c-fos were determined by Western Blot. Results Elemene can remarkably inhibited the growth of Hela cell and its IC50 was 80.6 ?g/mL. The luciferase activity of transcription factor ELK1 in Hela cells treated with elemene was inhibited. The protein expression of phosphorated ELK1 and its target gene c-fos in Hela cells treated with elemene were down-regulated. Conclusion Elemene can inhibit human cervix cancer Hela cell proliferation,which may be related with suppression of c-fos gene through inhibiting expression of phosphorated ELK1.

The translation inhibitor anisomycin induces Elk-1-mediated transcriptional activation of egr-1 through multiple mitogen-activated protein kinase pathways

The early growth response-1 gene (egr-1) encodes a zinc-finger transcription factor Egr-1 and is rapidly inducible by a variety of extracellular stimuli. Anisomycin (ANX), a protein synthesis inhibitor, stimulates mitogen-activated protein kinase (MAPK) pathways and thereby causes a rapid induction of immediate-early response genes. We found that anisomycin treatment of U87MG glioma cells resulted in a marked, time-dependent increase in levels of Egr-1 protein. The results of Northern blot analysis and reporter gene assay of egr-1 gene promoter (Pegr-1) activity indicate that the ANX- induced increase in Egr-1 occurs at the transcriptional level. Deletion of the serum response element (SRE) in the 5'-flanking region of egr-1 gene abolished ANX-induced Pegr-1 activity. ANX induced the phosphorylation of the ERK1/2, JNK, and p38 MAPKs in a time-dependent manner and also induced transactivation of Gal4-Elk-1, suggesting that Elk-1 is involved in SRE-mediated egr-1 transcription. Transient transfection of dominant-negative constructs of MAPK pathways blocked ANX-induced Pegr-1 activity. Furthermore, pretreatment with specific MAPK pathway inhibitors, including the MEK inhibitor U0126, the JNK inhibitor SP600125, and the p38 kinase inhibitor SB202190, completely inhibited ANX-inducible expression of Egr-1. Taken together, these results suggest that all three MAPK pathways play a crucial role in ANX-induced transcriptional activation of Pegr-1 through SRE-mediated transactivation of Elk

Effects of elk antlers ethanolic fluidextract on behavior and immune function of aging model mice / 中华中医药杂志

Objective: To observe the effect of elk antlers ethanolic fluidextract on behavior and immune function of aging model mice. Methods: ICR mice were randomly divided into 4 groups: Normal control group (NG), model control group (MG), low-dose drug treatment group (LG,2g/kg) and high-dose drug treatment group (HG,4g/kg). Mice were given subcutaneous injection of D-galactose (D-gal) at 120 mg/kg to induce subacute aging model. At the same time LG and HG were respectively administrated corresponding concentration of elk antlers ethanolic extract. Six weeks later, the learning and memory test was run by Y-maze. Then single agar immunodiffusion method was used to detect IgG level in serum, and spleen lymphocyte transforming stimulation index (SI) was determined by methyl thiazolyl tetrazolium(MTT) method as well as the concentration of Interleukin-2(IL-2) and interferon-gama(IFN-?) in serum were determined by ELISA method. Results: The memory and immune function of aging mice declined signif icantly. Elk antlers ethanolic fluidextract could obviously improve memory ability, increase the IgG level, raise the lymphocyte transforming SI, and elevate the concentration of IL-2 and IFN-? in model mice induced by D-gal. Conclusions: Elk antlers ethanolic extract could improve behavior and immune function of aging mice to delay aging process.

Mycobacterium bovis Infection in a Farmed Elk in Korea

A case of tuberculosis is reported in an eight-year-old, male, elk (Cervus elaphus nelsoni). The elk showed severe coughing, respiratory distress, abdominal breathing, anorexia, and severe progressive emaciation in the elk farm. At necropsy, the elk appeared in poor body condition. Mild enlargement of retropharyngeal and submandibular lymph node was observed in the head. Diffuse fibrinous pleuritis and purple red lobar pneumonia were found in the thorax. Well demarcated numerous dark yellow discrete or confluent nodules from 0.3 to 2 cm in diameter were scattered in the whole lung. Bronchial and mediastinal lymph nodes were also enlarged. Histopathologically, lungs had typical classical tuberculous granulomas, multiple abscesses, and numerous macrophages and Langhans giant cells infiltration in alveolar lumen. In the lymph nodes, there were small clusters of necrosis and infiltration of numerous macrophages, epithelioid cells, and Langhans giant cells. With the acid-fast staining, numerous mycobacteria were revealed in the lung and lymph nodes. According to this study, there are differences of the histopathologic lesions and the numbers of acid-fast bacilli in the lesions between this elk and cattle. Mycobacterium bovis was confirmed as a causative agent in this elk using bacterial isolation, biochemical characteristics, and PCR technique. The isolate was negative for niacin test, nitrate reductase, and pyrazinamidase. This is a first report for bovine tuberculosis of farmed elk in Asia.

The Induction of Immediate Early Genes and Phosphorylation of p42, p44 MAPK and Elk-1 by Kainic Acid in Developing Rat Hippocampus / 신경정신의학

OBJECTIVES: In order to investigate the maturational process of intracellular signal transduction system in rat brain, we studied the induction of the immediate early genes(IEGs)c-fos, junB, and TIS1 in each developmental stage after kainic acid(KA)induced seizure in young rat hippocampus and then compared these with the results after electroconvulsive shock(ECS) And to elucidate the induction mechanism of c-fos via mitogen-activated protein kinase(MAPK)by KA in each developmental stage, we investigated the phosphorylation of p42, p44 MAPK and Elk-1 after KA treatment in young rat hippocampus. METHODS: We examined the induction patterns of IEGs by northern blot analysis, and the phosphorylation of p42, p44 MAPK and Elk-1 by immunoblotting in rat hippocampus at post-natal day 7, 14, and 21(P7, P14 & P21) respectively after intraperitoneal injection of KA. RESULTS: Unlike ECS, KA did not induce c-fos, junB, and TIS1 in P7 hippocampus. But these genes were apparently induced at P14 and to an adult level at P21. These three IEGs showed similar temporal patterns of induction in each developmental stage. Although the basal level of phosphorylated 42p, 44p MAPK was considerable in P7 rat hippocampus, the increase of phosphorylation after KA treatment was observed at P14 . While the phosphorylation of Elk-1 was detected with high basal level in P7 rat, the amount of phosphorylated Elk-1 was not changed after KA treatment. CONCLUSION: Our results suggest that the differences in IEGs induction patterns between KA and ECS may be due to the differences in the activated signal transduction pathways. And our results also implicate that the signal transduction system involved in MAPK phosphorylation after KA treatment mature with aging and c-fos induction via MAPK activation may be regulated through some pathways other than Elk-1 in rat hippocampus.

Studies on anti-ageing effect of elk antlers ethanolic fluidextracr / 中成药

AIM: To study the anti ageing effect of elk antlers ethanolic fluidextract. METHODS: The subacute ageing model mice induced by D galactose was established and was given elk antlers ethanolic fluidextract for 30 days. SOD and MDA activity of the blood in the mice was determined at the end of experiment. The anti stress action and the immunomodulation were measured by determining the surviving time under hypoxic condition and swimming time and by determining the immune organ index, respectively. RESULTS: Elk antlers ethanolic fluidextract could raise SOD activity and reduce MDA content of the blood in subacute ageing model mice. It could prolong the surviving time under hypoxic conditon and swimming time in mice. It could also increase spleen index and reduce thymus index in mice. CONCLUSION: Elk antlers ethanolic fluidextract has anti oxidation action. It can strengthen the ability to bear hypoxic condition and tiredness in mice.It has certain action to regulate immune function.