• BMB Reports
• /
• 제42권9호
• /
• pp.552-560
• /
• 2009

Cyclooxygenases (COX-1 and COX-2) are ER-resident proteins that catalyze the committed step in prostanoid synthesis. COX-1 is constitutively expressed in many mammalian cells, whereas COX-2 is usually expressed inducibly and transiently. Abnormal expression of COX-2 has been implicated in the pathogenesis of chronic inflammation and various cancers; therefore, it is subject to tight and complex regulation. Differences in regulation of the COX enzymes at the posttranscriptional and posttranslational levels also contribute significantly to their distinct patterns of expression. Rapid degradation of COX-2 mRNA has been attributed to AU-rich elements (AREs) at its 3’UTR. Recently, microRNAs that can selectively repress COX-2 protein synthesis have been identified. The mature forms of these COX proteins are very similar in structure except that COX-2 has a unique 19-amino acid (19-aa) segment located near the C-terminus. This C-terminal 19-aa cassette plays an important role in mediation of the entry of COX-2 into the ER-associated degradation (ERAD) system, which transports ER proteins to the cytoplasm for degradation by the 26S proteasome. A second pathway for COX-2 protein degradation is initiated after the enzyme undergoes suicide inactivation following cyclooxygenase catalysis. Here, we discuss these molecular determinants of COX-2 expression in detail.

• IMMUNE NETWORK
• /
• 제6권4호
• /
• pp.204-210
• /
• 2006

Background: Nitric oxide (NO) in articular chondrocytes regulates dedifferentiation and inflammatory responses by modulating MAP kinases. In this study, we investigated whether the Src kinase in chondrocytes regulates NO-induced dedifferentiation and cyclooxygenase-2 (COX-2) expression. Methods: Primary chondrocytes were treated with various concentrations of SNP for 24 h. The COX-2 and type II collagen expression levels were determined by immunoblot analysis, and prostaglandin $E_2\;(PGE_2)$ was determined by using a $PGE_2$ assay kit. Expression and distribution of p-Caveolin and COX-2 in rabbit articular chondrocytes and cartilage explants were determined by immunohistochemical staining and immunocytochemical staining, respectively. Results: SNP treatment stimulated Src kinase activation in a dose-dependent manner in articular chondrocytes. The Src kinase inhibitors PP2 [4-amino-5-(4-chlorophenyl)-7-(t-butyl)pyrazolo(3,4-d)pyrimidine], a significantly blocked SNP-induced p38 kinase and caveolin-1 activation in a dose-dependent manner. Therefore, to determine whether Src kinase activation is associated with dedifferentiation and/or COX-2 expression and $PGE_2$ production. As expected, PP2 potentiated SNP-stimulated dedifferentiation, but completely blocked both COX-2 expression and $PGE_2$ production. And also, levels of p-Caveolin and COX-2 protein expression were increased in SNP-treated primary chondrocytes and osteoarthritic and rheumatoid arthritic cartilage, suggesting that p-Caveolin may playa role in the inflammatory responses of arthritic cartilage. Conclusion: Our previously studies indicated that NO caused dedifferentiation and COX-2 expression is regulated by p38 kinase through caveolin-1 (1). Therefore, our results collectively suggest that Src kinase regulates NO-induced dedifferentiation and COX-2 expression in chondrocytes via p38 kinase in association with caveolin-1.

• Molecules and Cells
• /
• 제37권10호
• /
• pp.759-765
• /
• 2014

N-myc downstream-regulated gene 2 (NDRG2), which is known to have tumor suppressor functions, is frequently down-regulated in breast cancers and potentially involved in preventing the migration and invasion of malignant tumor cells. In the present study, we examined the inhibitory effects of NDRG2 overexpression, specifically focusing on the role of cyclooxygenase-2 (COX-2) in the migration of breast cancer cells. NDRG2 overexpression in MDA-MB-231 cells inhibited the expression of the COX-2 mRNA and protein, the transcriptional activity of COX-2, and prostaglandin $E_2$ ($PGE_2$) production, which were induced by a treatment with phorbol-12-myristate-13-acetate (PMA). Nuclear transcription factor-${\kappa}B$ (NF-${\kappa}B$) signaling attenuated by NDRG2 expression resulted in a decrease in PMA-induced COX-2 expression. Interestingly, the inhibition of COX-2 strongly suppressed PMA-stimulated migration and invasion in MDA-MB-231-NDRG2 cells. Moreover, siRNA-mediated knockdown of NDRG2 in MCF7 cells increased the COX-2 mRNA and protein expression levels and the PMA-induced COX-2 expression levels. Consistent with these results, the migration and invasion of MCF7 cells treated with NDRG2 siRNA were significantly enhanced following treatment with PMA. Taken together, our data show that the inhibition of NF-${\kappa}B$ signaling by NDRG2 expression is able to suppress cell migration and invasion through the down-regulation of COX-2 expression.

• IMMUNE NETWORK
• /
• 제13권2호
• /
• pp.75-79
• /
• 2013

Evidence for immunoregulatory roles of prostaglandins (PGs) is accumulating. Since our observation of PG production by human follicular dendritic cells (FDCs), we investigated the regulatory mechanism of PG production in FDC and attempted to understand the functions of released PGs in the responses of adjacent lymphocytes. Here, using FDC-like cells, HK cells, we analyzed protein expression alterations in cyclooxygenase-2 (COX-2) in the presence of IL-4 or histone deacetylase (HDAC) inhibitors. Both IL-4 and HDAC inhibitors suppressed COX-2 expression in dose-dependent manners. Their effect was specific to COX-2 and did not reach to COX-1 expression. Interestingly, HDAC inhibitors gave rise to an opposing effect on COX-2 expression in peripheral blood monocytes. Our results suggest that IL-4 may regulate COX-2 expression in FDCs by affecting chromatin remodeling and provide insight into the role of cellular interactions between T cells and FDC during the GC reaction. Given the growing interests in wide-spectrum HDAC inhibitors, the differential results on COX-2 expression in HK cells and monocytes raise cautions on their clinical use.

• 한국독성학회:학술대회논문집
• /
• 한국독성학회 2003년도 춘계학술대회 논문집
• /
• pp.13-14
• /
• 2003

Ceramide, a potential cell death marker formed by sphingomyelinase, is involved in the expression of cyclooxygenase-2 (COX-2). This study examines the effect of C2-ceramide (C2), a cell-permeable ceramide analog, on the LPS-inducible COX-2 expression and signaling pathways. C2 did not induce COX-2, but potentiated LPS-inducible COX-2 expression in Raw264.7 cells, whereas dihydro-C2 was inactive.(omitted)

• 한국융합학회논문지
• /
• 제10권2호
• /
• pp.331-337
• /
• 2019

연구목적 : 4x, 30x, 30c, and 200c 농도의 동종약물 Arnica montana (A. montana)를 1차 배양된 생쥐 연골세포에 적용하여 염증관련 인자의 변화를 관찰하고자 하였다. 연구방법 : 본 연구는 collagen type II (Coll-2), cyclooxygenase-2 (COX-2) 발현 그리고 prostaglandin 2 (PGE2) 분비에 대해 조사하였다. 결과: 4x, 30x 그리고 30c의 A. montana를 처리하였을 때, Coll-2의 mRNA 발현이 감소하였으며, 30x A. montana의 경우 COX-2 mRNA의 발현이 증가하였다. 또한 COX-2 단백질 발현은 30x와 30c의 A. montana 처리 시 증가함을 보였다. PGE2 분비 또한 30c에서 증가함을 관찰하였다. 결론 : A. montana 처리에 따라 생쥐의 연골세포의 분화 억제를 확인하였으며, 염증관련 인자인 COX-2 및 PGE2의 발현이 증가함을 확인하였다.

• 대한의생명과학회지
• /
• 제15권2호
• /
• pp.141-146
• /
• 2009

Paclitaxel, an antimicrotubule agent, binds to beta-tubulin in the microtubule and stabilizes the polymer, thereby repressing dynamic instability. Here, we have demonstrated that microtubule cytoskeletal architecture involved in regulation of the COX-2 expression in chondrocyte treated with paclitaxel. Paclitaxel enhanced COX-2 expression and prostaglandin E2 production, as indicated by the Western blot analysis, reverse transcriptase PCR(RT-PCR) and immunofluorescence staining, and $PGE_2$ assay, respectively. In our previous data have shown that paclitaxel treatment stimulated activation of ERK-1/2 and p38 kinase(Im et al., 2009). SB203580, an inhibitor of p38 kinase, blocked the induction of COX-2 expression by paclitaxel. Also PD98059, an inhibitor of ERK-1/2 kinase was blocked the induced COX-2 expression. These results indicate that activation of ERK-1/2 and p38 kinase is required for COX-2 expression induced by paclitaxel in rabbit articular chondrocytes.

• Clinical and Experimental Reproductive Medicine
• /
• 제25권1호
• /
• pp.25-33
• /
• 1998

Cyclooxygenase (COX) is an enzyme involved in the conversion of arachidonic acid to prostaglandins (PGs), and exists in two forms, COX-1 and COX-2. COX has been reported to be involved in early implantation by secretion of PGs which causes permeability of vessels and reaction of decidual cells around the implantation site. Recently, in mice and sheep studies, COX-1 and COX-2 expression in the endometrium has been reported to be different according to implantation and stages of the estrous cycle, but expression of COX-1 and COX-2 in human endometrium during the menstrual cycle has not yet been established. The purpose of this study was to observe the variances of COX-1 and COX-2 expression by immunohistochemical staining in endometrial samples obtained from human hysterectomy specimens and biopsies of women of reproductive age according to different stages of the menstrual cycle. Also, we attempted to observe COX-1 and COX-2 expression in the epithelial and stromal cells of the endometrium obtained during the mid-secretory phase, which were cultured separately. COX-2 showed a cyclic pattern of expression according to the different stages of the menstrual cycle and was strongly expressed particularly at the mid-secretory phase which corresponds to the time of implantation. However, COX-1 tended to be increased in the early proliferative, and mid- and late secretory phases, but was also expressed in the whole menstrual cycle showing no particular pattern. In the separately cultured cells COX-1 was expressed in epithilial cells and COX-2 in the stromal cells. The above results suggest that since COX-2 is expressed at the same time as implantation and cultured cells display a specific secretory pattern, COX-2 has inductive endocrine enzyme properties and has an important effect on endometrial cells during implantation. Also, COX-2 expression in endometrial cells may be utilized as a useful marker of endometrial maturation.

• 대한약학회:학술대회논문집
• /
• 대한약학회 2003년도 Proceedings of the Convention of the Pharmaceutical Society of Korea Vol.1
• /
• pp.190.2-191
• /
• 2003

Production of prostaglandins involved in renal salt and water homeostasis is modulated by regulated expression of the inducible form of cyclooxygenase-2 (COX-2) at restricted sites in the rat kidney. COX-2 expression in the kidney is regulated by dietary salt intake, but the mechanism of its action is not fully understood. We have previously that high salt regulates COX-2 expression in rat kidney. (omitted)

• 대한한의학회지
• /
• 제25권3호
• /
• pp.90-98
• /
• 2004

Objectives : The present study was undertaken to investigate the molecular mechanisms of Ichungwhan for inhibition of cyclooxygenase-2 (COX-2) gene expression via suppression of NF-κB (nuclear factor κB) using aged rats. NF-κB is the most important modulator of inflammation and NF-κB regulates the gene expression of several pro-inflammatory cytokines, such as COX-2. Methods : In the experiment, we investigated the scavenging property of Ichungwhan on reactive species (RS) including nitrogen-derived species (RNS), measured by DCF-DA (2,7-dichlorodihydrofluorexcein diacetate) / DHR 123 (dihydrorhodamine 123) assay. Protein expression levels of COX-2, NF-κB, p-ERK and p-p38 were assayed by western blot. Results : We showed that Ichungwhan inhibits RS including RNS and inhibits NF-κB activation by blocking the dissociation of inhibitory IκB-β via suppression of IKK pathway. Also, Ichungwhan inhibits COX-2 gene expression. Conclusions : These findings suggest that Ichungwhan modulates COX-2 gene expression via suppression of the NF-κB pathway.