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Polarized expression of monocarboxylate transporters in human retinal pigment epithelium and ARPE-19 cells.

PURPOSE: To evaluate the expression and subcellular distribution of proton-coupled monocarboxylate transporters (MCTs) in human RPE in vivo and determine whether ARPE-19 cells retain the ability to express and differentially polarize these transporters. METHODS: Total RNA was prepared from human donor eyes and from ARPE-19 cell cultures. Expression of MCT transcripts was evaluated by RT-PCR amplification. Expression of MCT proteins in human RPE and ARPE-19 cells was evaluated by immunolocalization and Western blot analysis with isoform-specific anti-peptide antibodies. RESULTS: The expression of MCTs in human RPE was investigated by immunofluorescence analysis on frozen sections of human donor eyes. MCT1 antibody labeled the apical membrane of the RPE intensely, whereas MCT3 labeling was restricted to the basolateral membrane. MCT4 was detected in the neural retina but not in the RPE. ARPE-19 cells constitutively expressed MCT1 and MCT4 mRNAs. Expression of MCT3 mRNA increased over time as ARPE-19 cells established a differentiated phenotype. Western blot analysis revealed that ARPE-19 cells expressed high levels of MCT1 and MCT4 but very little MCT3 protein. Sections of differentiated ARPE-19 cells were labeled with MCT1, MCT4, and glucose transporter-1 antibodies. MCT1 was polarized to the apical membrane and MCT4 to the basolateral membrane, whereas GLUT1 was expressed in both membrane domains. CD147, which is necessary for targeting MCTs to the plasma membrane, was detected in the apical and basolateral membranes of human RPE in situ and ARPE-19 cells. CONCLUSIONS: These studies demonstrate for the first time that human RPE expresses two proton-coupled monocarboxylate transporters: MCT1 in the apical membrane and MCT3 in the basolateral membrane. The coordinated activities of these two transporters could facilitate the flux of lactate from the retina to the choroid. ARPE-19 cells express two MCT isoforms, polarized to different membrane domains: MCT1 to the apical membrane and MCT4 to the basolateral membrane. The polarized expression of MCTs in ARPE-19 demonstrates that these cells retain the cellular machinery necessary for transepithelial transport of lactate.

Animals↗

Loss of MCT1, MCT3, and MCT4 expression in the retinal pigment epithelium and neural retina of the 5A11/basigin-null mouse.

PURPOSE: The neural retina expresses multiple monocarboxylate transporters (MCTs) that are likely to play a key role in the metabolism of the outer retina. Recently, it was reported that targeting of MCT1 and -4 to the plasma membrane requires association with 5A11/basigin (CD147). In the present study, the hypothesis that reduced amplitudes in the electroretinograms in the 5A11/basigin null mouse (Bsg(-/-)) may be linked to altered expression of MCTs was studied. METHODS: The expression and subcellular distribution of MCTs in Bsg(-/-) mice was analyzed by immunofluorescence microscopy with isoform-specific antibodies. Protein expression was analyzed by Western blot analysis, and mRNA expression was examined with RT-PCR. RESULTS: Immunofluorescence labeling of tissue sections from the Bsg(-/-) mice revealed a dramatic reduction in labeling with MCT antibodies. There was a loss of MCT1 labeling in the apical membrane of the RPE and in the neural retina. MCT3, which is expressed in the basolateral membrane of the RPE wild-type mouse, was expressed at very low levels in both the apical and basolateral membranes of the Bsg(-/-) mouse. There was no change in expression or distribution of the glucose transporter (GLUT)-1 in the RPE and retina of the Bsg(-/-) mouse. Western blot analysis of detergent-soluble lysates prepared from wild-type and Bsg(-/-) eyes confirmed that the levels of MCT1, MCT3, and MCT4 protein were severely reduced in Bsg(-/-) mice. RT-PCR analyses of mRNA levels from wild-type and Bsg(-/-) mice demonstrated that the MCT1 transcript was expressed at normal levels in Bsg(-/-) mice. CONCLUSIONS: In Bsg(-/-) mice, there is a severe reduction in accumulation of the MCT1 and -3 proteins in the RPE and a concomitant reduction in MCT1 and -4 in the neural retina supporting a role for 5A11/basigin in the targeting of these transporters to the plasma membrane. Decreased expression of MCT1 and -4 on the surfaces of Müller and photoreceptor cells may compromise energy metabolism in the outer retina, leading to abnormal photoreceptor cell function and degeneration.

Animals↗

Retina-specific expression of 5A11/Basigin-2, a member of the immunoglobulin gene superfamily.

PURPOSE: 5A11/Basigin has recently been identified as a critical glycoprotein for full maturity and function of the mouse retina. However, the biological function of 5A11/Basigin has yet to be determined. Previous reports indicate the presence of multiple 5A11/Basigin polypeptides within the retina. Therefore, in an effort to determine the function of 5A11/Basigin, the molecular diversity of its expression was evaluated. METHODS: Northern blot and immunoblot techniques were used to evaluate the number of forms of 5A11/Basigin in the mouse retina. cDNA cloning, using a mouse retina library or RT-PCR from rat, chicken, zebrafish, and human retina, was performed to determine the sequence of 5A11/Basigin transcripts. A peptide was generated, based on the deduced amino acid sequence, for subsequent antibody production. Localization of 5A11/Basigin expression was evaluated by immunoblot, immunohistochemistry, and real-time RT-PCR. RESULTS: Two 5A11/Basigin transcripts of approximately 1.5 kb and approximately 1.8 kb, which correspond to glycosylated proteins of approximately 45 and approximately 55 kDa, respectively, were identified in mouse retina. The shorter form was previously cloned. However, the longer form, a splice variant of mouse 5A11/Basigin, is a member of the immunoglobulin gene superfamily and has been named 5A11/Basigin-2. Homologous transcripts were also cloned from rat, chicken, zebrafish, and human retina. 5A11/Basigin-2 expression was limited to the retina, specifically to photoreceptor cells, where it appeared to be most concentrated in the inner segments. CONCLUSIONS: The specific and limited expression of 5A11/Basigin-2 explicitly within photoreceptor cells implies that this glycoprotein plays a fundamental role within the retina. However, its role remains to be determined.

Amino Acid Sequence↗

Tumor collagenase stimulatory factor (TCSF) expression and localization in human lung and breast cancers.

Tumor cell-derived collagenase stimulatory factor (TCSF) stimulates in vitro the biosynthesis of various matrix metalloproteinases involved in tumor invasion, such as interstitial collagenase, gelatinase A, and stromelysin 1. The expression of TCSF mRNAs was studied in vivo, using in situ hybridization and Northern blotting analysis, in seven normal tissues and in 22 squamous cell carcinomas of the lung, and in seven benign proliferations and in 22 ductal carcinomas of the mammary gland. By in situ hybridization, TCSF mRNAs were detected in 40 of 44 carcinomas, in pre-invasive and invasive cancer cells of both lung and breast cancers. TCSF mRNAs and gelatinase A mRNAs were both visualized in the same areas in serial sections in breast cancers, and were expressed by different cells, tumor cells, and fibroblasts. The histological results were confirmed by Northern blot analysis, which showed a higher expression of TCSF mRNAs in cancers than in benign and normal tissues. These observations support the hypothesis that TCSF is an important factor in lung and breast tumor progression.

Antigens, CD↗

Expression of the extracellular matrix metalloproteinase inducer (EMMPRIN) and the matrix metalloproteinase-2 in bronchopulmonary and breast lesions.

Tumor cells interact with stromal cells via soluble or cell-bound factors stimulating the production of matrix metalloproteinases (MMPs), a group of enzymes largely involved in the extracellular matrix (ECM) remodeling in tumor invasion. Among these factors, extracellular matrix metalloproteinase inducer (EMMPRIN) has been shown to stimulate in vitro the fibroblast production of various MMPs such as interstitial collagenase (MMP-1), stromelysin-1 (MMP-3), and gelatinase A (MMP-2). In this study, the EMMPRIN protein was detected by immunohistochemistry prominently in malignant proliferations of the breast and the lung. It was present at the surface of both tumor epithelial and peritumor stromal cells. Because previous studies have reported that stromal cells do not express EMMPRIN mRNAs, it is very likely that EMMPRIN is bound to stromal cells via a specific receptor. Moreover, our observations also demonstrated that the same peritumor stromal cells strongly express MMP-2. Our results show that EMMPRIN is an important factor in tumor progression by causing tumor-associated stromal cells to increase their MMP-2 production, thus facilitating tumor invasion and neoangiogenesis. (J Histochem Cytochem 47: 1575-1580, 1999)

Adenocarcinoma↗

Lack of effect of short-term depletion of plasma complement C3 on the survival of syngeneic dopaminergic neurons following grafting into the intact rat striatum.

Metabolically compromised cells may be subject to complement-mediated cytotoxicity. The aim of this study was to clarify to what extent plasma complement C3 might contribute to the low survival (5-20%) of grafted dopaminergic neurons. The survival of intrastriatal cell suspension grafts of syngeneic dopaminergic, tyrosine hydroxylase (TH)-containing neurons was compared in rats subjected to short-term i.v. treatment with 1) cobra venom factor (CVF), or 2) placebo treatment. Depletion of plasma complement C3 by CVF was confirmed by crossed immunoelectrophoresis. With 159 +/- 37 (mean +/- SEM) TH-immunoreactive and 154 + /- 40 TH mRNA-expressing neurons in the CVF-treated rats (n = 9), and 117 +/- 34 TH-immunoreactive and 160 +/- 49 TH mRNA-expressing neurons in placebo rats (n = 6), the CVF treatment did not increase the survival of the grafted dopaminergic neurons. Similarly, CVF had no apparent effect on the astroglial, microglial, or oligodendroglial cell response within and around the graft. The data indicate that depletion of plasma complement C3 at the time of grafting has no effect on the long-term survival of syngeneic ventral mesencephalic dopaminergic neuronal grafts.

Animals↗

A phase 2/3 multicenter randomized clinical trial of ABX-CBL versus ATG as secondary therapy for steroid-resistant acute graft-versus-host disease.

Treatment for steroid-resistant acute graft-versus-host disease (GVHD) has had limited success. ABX-CBL is a hybridoma-generated murine IgM monoclonal antibody against the CD147 antigen, weakly expressed on human leukocytes and up-regulated on activated lymphocytes. A prospective, multicenter, open-label, randomized clinical trial comparing ABX-CBL to antithymocyte globulin (ATG) for treatment of steroid-resistant acute GVHD was conducted in 95 patients at 21 centers. Forty-eight patients received ABX-CBL daily for 14 consecutive days followed by up to 6 weeks of ABX-CBL twice weekly. Forty-seven patients received equine ATG, 30 mg/kg every other day for a total of 6 doses with additional courses as needed. By day 180, overall improvement was similar in the patients receiving ABX-CBL and in those receiving ATG (56% versus 57%, P = .91). Patient survival at 18 months was less favorable on ABX-CBL than on ATG (35% versus 45%), with the 95% confidence interval ruling out that ABX-CBL provides at least a 10.4% improvement. Data from this trial suggest that ABX-CBL does not offer an improvement over ATG in the treatment of acute steroid-resistant GVHD. This prospective, multicenter, randomized clinical trial for steroid-resistant acute GVHD serves as a model for future evaluation of new agents.

Adolescent↗

Unavailability of CD147 leads to selective erythrocyte trapping in the spleen.

Adhesive interactions with stromal cells and the extracellular matrix are essential for the differentiation and migration of hematopoietic progenitors. In the erythrocytic lineage, a number of adhesion molecules are expressed in the developing erythrocytes and are thought to play a role in the homing and maturation of erythrocytic progenitors. However, many of these molecules are lost during the final developmental stages leading to mature erythrocytes. One of the adhesion molecules that remains expressed in mature, circulating erythrocytes is CD147. This study shows that blockade of this molecule on the cell surface by treatment with F(ab')(2) fragments of anti-CD147 monoclonal antibody disrupts the circulation of erythrocytes, leading to their selective trapping in the spleen. Consequently, mice develop an anemia, and de novo, erythropoietin-mediated erythropoiesis in the spleen. In contrast, these changes were not seen in mice similarly treated with another antierythrocyte monoclonal antibody with a different specificity. These results suggest that the CD147 expressed on erythrocytes likely plays a critical role in the recirculation of mature erythrocytes from the spleen into the general circulation. (Blood. 2001;97:3984-3988)

Animals↗

The functional interactions between CD98, beta1-integrins, and CD147 in the induction of U937 homotypic aggregation.

CD98 is expressed on both hematopoietic and nonhematopoietic cells and has been implicated in a variety of different aspects of cell physiology and immunobiology. In this study, the functional interactions between CD98 and other adhesion molecules on the surface of the promonocyte line U937 are examined by means of a quantitative assay of cell aggregation. Several of the CD98 antibodies induced homotypic aggregation of these cells without affecting cellular viability or growth. Aggregation induced by CD98 antibodies could be distinguished from that induced by beta1-integrin (CD29) ligation by lack of sensitivity to EDTA and by increased sensitivity to deoxyglucose. Aggregation induced via CD98 and CD29 could also be distinguished by the pattern of protein tyrosine phosphorylation induced. Some CD29 antibodies partially inhibited CD98-induced aggregation, and these antibodies were neither agonistic for aggregation nor inhibitors of beta1-integrin binding to substrates. Conversely, some CD98 antibodies were potent inhibitors of CD29-induced aggregation. Antibodies to beta2 integrins also partially inhibited CD98-induced aggregation. Unexpectedly, 2 antibodies to CD147, an immunoglobulin superfamily member whose function has remained unclear, were also potent inhibitors of both the aggregation and the protein tyrosine phosphorylation induced via CD98 ligation. The results of this study support a central role for CD98 within a multimolecular unit that regulates cell aggregation.

Antibodies↗

Treatment of steroid-refractory acute graft-versus-host disease with anti-CD147 monoclonal antibody ABX-CBL.

ABX-CBL, an immunoglobulin M murine monoclonal antibody, recognizes CD147 and initiates cell killing through complement-mediated lysis. In a dose-finding trial, 27 patients with steroid-refractory acute graft-versus-host disease (GVHD) received ABX-CBL at 0.01 (presumed no effect dose), 0.1, 0.2, or 0.3 mg/kg per day, and an additional 32 patients were given ABX-CBL at 0.2 or 0.15 mg/kg per day. All patients had undergone allogeneic transplantation for malignant or nonmalignant disorders and received GVHD prophylaxis, generally with methotrexate- and cyclosporine-containing regimens. None responded to methylprednisolone, given for a minimum of 3 days. ABX-CBL was started 20 to 236 (median, 47) days after transplantation; it was given for 7 consecutive days and was followed by 2 infusions per week for 2 more weeks. Among 51 patients evaluable for efficacy, 26 (51%) responded, including 13 with complete responses (CR) and 13 with partial responses (PR). CR lasting 14 days or longer or PR lasting 7 days or longer occurred in 21 (41%; 8 CR, 13 PR) patients, including 19 of 43 (44%) patients who received 0.1 to 0.3 mg/kg ABX-CBL and 2 of 8 (25%) patients given 0.01 mg/kg per day. Myalgias at doses 0.2 mg/kg or greater were dose limiting and resolved without sequelae. Causes of death included organ failure, progressive GVHD, and infection. No death was attributed to ABX-CBL. At 6 months after the initiation of ABX-CBL therapy, 26 (44%) patients were surviving. These results are encouraging. Further studies on the use of ABX-CBL in the management of GVHD are warranted.

Acute Disease↗

A novel form of the membrane protein CD147 that contains an extra Ig-like domain and interacts homophilically.

BACKGROUND: CD147 is a broadly distributed integral membrane glycoprotein with two Ig-like domains implicated in a wide range of functions. It is associated at the cell surface with the monocarboxylate transporters MCT1 and 4 but interactions of the extracellular region have not been characterised. RESULTS: We report the characterisation of a form of CD147 with an additional membrane-distal Ig-like domain. In contrast to the two domain form, this three domain form of CD147 interacts homophilically. Surface plasmon resonance analysis using recombinant proteins showed that the interaction was of low affinity (KD approximately 40 microM) and this is typical of many interactions between membrane proteins. cDNA for the 3 domain form are rare but have been identified in human and mouse retina. CONCLUSION: The finding that the three domain form of CD147 has an extracellular ligand, that is it interacts homophilically, suggests this interaction may be important in aligning lactate transporters in the retina where lactate is an important metabolite.

Amino Acid Sequence↗

Involvement of CD147 in overexpression of MMP-2 and MMP-9 and enhancement of invasive potential of PMA-differentiated THP-1.

BACKGROUND: During infection and inflammation, circulating blood monocytes migrate from the intravascular compartments to the extravascular compartments, where they mature into tissue macrophages. The maturation process prepares the cells to actively participate in the inflammatory and immune responses, and many factors have been reported to be involved in the process. We found in our study that CD147 played a very important role in this process. RESULTS: By using PMA-differentiated human monocyte cells line THP-1, we found that CD147 mediated matrix metalloproteinases (MMPs) expression of the leukemic THP-1 cells and thus enhanced the invasiveness of THP-1 cells. After 24 hours of PMA-induced monocyte differentiation, the mean fluorescence intensity of CD147 in differentiated THP-1 cells (289.61 +/- 31.63) was higher than that of the undifferentiated THP-1 cells (205.1 +/- 19.25). There was a significant increase of the levels of proMMP-2, proMMP-9 and their activated forms in the differentiated THP-1 cells. Invasion assays using reconstituted basement membrane showed a good correlation between the invasiveness of THP-1 cells and the production of MMP-2 and MMP-9. The difference in the MMPs expression and the invasive ability was significantly blocked by HAb18G/CD147 antagonistic peptide AP-9. The inhibitory rate of the secretion of proMMP-9 in the undifferentiated THP-1 cells was 45.07%. The inhibitory rate of the secretion of proMMP-9, the activated MMP-9 and proMMP-2 in the differentiated THP-1 cells was 52.90%, 53.79% and 47.80%, respectively. The inhibitory rate of invasive potential in the undifferentiated cells and the differentiated THP-1 cells was 41.82 % and 25.15%, respectively. CONCLUSION: The results suggest that the expression of CD147 is upregulated during the differentiation of monocyte THP-1 cells to macrophage cells, and CD147 induces the secretion and activation of MMP-2 and MMP-9 and enhances the invasive ability of THP-1 cells. The matured monocytes / macrophages, via their high expression of CD147, may play an important role in promoting the tissue repair or tissue damage during their inflammatory response.

Basigin↗

Expression of CD147 on monocytes/macrophages in rheumatoid arthritis: its potential role in monocyte accumulation and matrix metalloproteinase production.

Monocytes/macrophages play an important role in rheumatoid arthritis (RA) pathogenesis. They can activate fibroblasts through many molecules, including IL-1 and tumor necrosis factor-alpha, but there have been very few reports on the role of CD147 in RA. In our study, the results of flow cytometry reveal that the mean fluorescence intensity (MFI) of CD147 expression on CD14+ monocytes of peripheral blood from RA patients was higher than that in normal control and ankylosing spondylitis (AS) patients. The MFI of CD147 expression on the CD14+ monocytes in RA synovial fluid was higher than that in RA peripheral blood. Immunohistochemical staining shows that CD147 expression in RA synovium correlated with matrix metalloproteinase (MMP)-1 expression. A double immunofluorescent assay shows that CD147 was expressed on CD68+ cells in RA synovium. The potential role of CD147 in cyclophilin A (CyPA)-mediated cell migration was studied using a chemotaxis assay in vitro and it was found that the addition of anti-CD147 antibody or a CD147 antagonistic peptide significantly decreased the chemotactic index of the mononuclear cells. The role of CD147 in MMP production and cell invasion in vitro were studied through the co-culture of human CD14+ monocytes or monocytic line THP-1 cells and human fibroblasts, as well as by gel zymography and an invasion assay. Significantly elevated release and activation of MMP-9 and/or MMP-2 were seen in the co-culture of human monocytes/THP-1 cells and fibroblasts compared with cultures of the cells alone. An increased number of cells invading through the filters in the invasion assays was also observed in the co-cultured cells. The addition of CD147 antagonistic peptide had some inhibitory effect, not only on MMP production but also on cell invasion in the co-culture. Our study demonstrates that the increased expression of CD147 on monocytes/macrophages in RA may be responsible for elevated MMP secretion, cell invasion and CyPA-mediated cell migration into the joints, all of which may contribute to the cartilage and bone destruction of RA. These findings, together with a better understanding of CD147, CyPA and RA, will help in the development of innovative therapeutic interventions for RA.

Adult↗

CD147 overexpression on synoviocytes in rheumatoid arthritis enhances matrix metalloproteinase production and invasiveness of synoviocytes.

Macrophage-like synoviocytes and fibroblast-like synoviocytes (FLS) are known as the most active cells of rheumatoid arthritis (RA) and are close to the articular cartilage in a position enabling them to invade the cartilage. Macrophage-like synoviocytes and FLS expression of matrix metalloproteinases (MMPs) and their interaction has aroused great interest. The present article studied the expression of CD147, also called extracellular matrix metalloproteinase inducer, on monocytes/macrophages and FLS from RA patients and its potential role in enhancing MMPs and the invasiveness of synoviocytes. Expression of CD147 on FLS derived from RA patients and from osteoarthritis patients, and expression of CD147 on monocytes/macrophages from rheumatic synovial fluid and healthy peripheral blood were analyzed by flow cytometry. The levels of CD147, MMP-2 and MMP-9 mRNA in FLS were detected by RT-PCR. The role of CD147 in MMP production and the cells' invasiveness in vitro were studied by the co-culture of FLS with the human THP-1 cell line or monocytes/macrophages, by gel zymography and by invasion assay. The results showed that the expression of CD147 was higher on RA FLS than on osteoarthritis FLS and was higher on monocytes/macrophages from rheumatic synovial fluid than on monocytes/macrophages from healthy peripheral blood. RT-PCR showed that the expressions of CD147, MMP-2 and MMP-9 mRNA was higher in RA FLS than in osteoarthritis FLS. A significantly elevated secretion and activation of MMP-2 and MMP-9 were observed in RA FLS co-cultured with differentiated THP-1 cells or RA synovial monocytes/macrophages, compared with those co-cultured with undifferentiated THP-1 cells or healthy control peripheral blood monocytes. Invasion assays showed an increased number of invading cells in the co-cultured RA FLS with differentiated THP-1 cells or RA synovial monocytes/macrophages. CD147 antagonistic peptide inhibited the MMP production and the invasive potential. Our studies demonstrated that the CD147 overexpression on monocytes/macrophages and FLS in RA patients may be responsible for the enhanced MMP secretion and activation and for the invasiveness of synoviocytes. These findings suggest that CD147 may be one of the important factors in progressive joint destruction of RA and that CD147 may be a potential therapeutic target in RA treatment.

Adult↗

Nutritional iron deprivation attenuates kainate-induced neurotoxicity in rats: implications for involvement of iron in neurodegeneration.

There is evidence suggesting that oxidative stress contributes to kainate neurotoxicity. Since iron promotes oxidative stress, the present study explores how change in nutritional iron content modulates kainate-induced neurotoxicity. Rats received an iron-deficient diet (ID) from 22 days of age for 4 weeks. One control group received the same diet supplemented with iron and another control group received standard rodent diet. Cellular damage after subcutaneous kainate (10 mg/kg) was assessed by silver impregnation and gliosis by staining microglia. ID reduced cellular damage in piriform and entorhinal cortex, in thalamus, and in hippocampal layers CA1-3. ID also attenuated gliosis, except in the hippocampal CA1 layer. Given involvement of zinc in hippocampal neurotransmission and in oxidative stress, we tested for a possible interaction of nutritional iron with nutritional zinc. Rats were made iron-deficient and then assigned to supplementation with iron, zinc, or iron + zinc. Controls were continued on ID diet. After 2 weeks, rats were treated with kainate. Iron supplementation abolished the protective effect of ID in piriform and entorhinal cortex. In hippocampal CA1 and dorsal thalamus, neither iron nor zinc supplementation alone abolished the protective effect of ID against cellular damage. Iron + zinc supplementation abolished ID protection in dorsal thalamus, but not in reuniens nucleus. Kainate-induced gliosis in CA1 remained unaffected by nutritional treatments. Thus, in piriform and entorhinal cortex, nutritional iron has a major impact on cellular damage and gliosis. In hippocampal CA1, gliosis may associate with synaptic plasticity not modulated by nutritional iron, while cellular damage is sensitive to nutritional iron and zinc.

Animals↗

Identification and characterization of extracellular matrix metalloproteinase inducer in human endometrium during the menstrual cycle in vivo and in vitro.

Extracellular matrix metalloproteinase inducer (EMMPRIN) participates in the breakdown of the extracellular matrix (ECM) by augmenting matrix metalloproteinase (MMP) expression. In the present study, we identified and characterized the menstrual cycle-dependent expression of EMMPRIN in human endometrium in vivo. At the proliferative phase of the menstrual cycle, EMMPRIN was detected in glandular epithelium of the basal layer in endometrium. In addition, at the superficial region of the functional layer, EMMPRIN was expressed in stroma but not glandular epithelium. At the secretory phase, EMMPRIN was found in both stroma and glandular epithelium of the functional layer and glandular epithelium of the basal layer. Furthermore, EMMPRIN colocalized with MMP-1/collagenase-1 in the glandular epithelium in vivo. Western blot analysis of tissue from the functional layer showed that EMMPRIN species with molecular weights of approximately 35 and 47 kDa were detected at the proliferative phase, whereas approximately 35- and 51-kDa EMMPRIN species were predominantly expressed at the secretory phase. In addition, the variant EMMPRIN molecules were found to differ in glycosylation. On the other hand, EMMPRIN was constitutively produced in primary cultured endometrial stromal and glandular epithelial cells. The production and glycosylation of EMMPRIN in the stromal cells were augmented by progesterone at the posttranscriptional and posttranslational stages, respectively. These results suggest for the first time that EMMPRIN is expressed in human endometrium during the menstrual cycle and that its expression and glycosylation are augmented by progesterone. Moreover, EMMPRIN may be involved in ECM breakdown at the interface between endometrial cells and ECM by using EMMPRIN-bound MMP-1.

Antigens, CD↗

Expression of extracellular matrix metalloproteinase inducer in human placenta and fetal membranes at term labor.

Matrix metalloproteinases (MMPs) are the main mediators of extracellular matrix (ECM) degradation during human parturition. However, the mechanisms involved in regulation of MMP production during parturition remain poorly understood. Recently, an extracellular matrix metalloproteinase inducer (EMMPRIN) has been shown to play a key role, as a local regulator, in stimulating MMP production in cancer systems. Whether EMMPRIN is expressed and stimulates MMP production in human placenta and fetal membranes is presently unknown. In this study, we investigated the expression of EMMPRIN at the levels of mRNA and protein in human term placenta and fetal membranes with or without labor. Western blot analysis showed that EMMPRIN protein was detected in term placenta and fetal membranes at two molecular masses of 40 and 65 kDa (glycosylated protein) and one of approximately 30 kDa (nonglycosylated protein). The ratio of 65 kDa EMMPRIN to total EMMPRIN significantly increased (P < 0.05) in term labor chorio-decidua and amnion compared with nonlabor chorio-decidua and amnion. Immunohistochemical analysis revealed that EMMPRIN was expressed in placental syncytiotrophoblast, amniotic epithelial cells, trophoblast cells of chorion laeve, and decidua parietalis. EMMPRIN was also detected at the mRNA level using RT-PCR in cultured placental syncytiotrophoblast, amniotic epithelial cells, and chorionic trophoblast cells. We conclude that human placenta and fetal membranes express EMMPRIN, with the potential to stimulate MMP production, thereby facilitating fetal membrane rupture and leading to detachment of the placenta and fetal membranes from the maternal uterus at the time of parturition.

Amnion↗

Extracellular matrix metalloproteinase inducer regulates metalloproteinases in human uterine endometrium.

CONTEXT: Endometrial remodeling occurs during each menstrual cycle in women and also during the establishment of endometriosis. Both processes involve the production of metalloproteinases (MMPs) by uterine endometrial cells. OBJECTIVE: The objective of this study was to determine whether tissue remodeling and endometrial invasion involve activation of MMPs by extracellular matrix metalloproteinase inducer (EMMPRIN). MAIN OUTCOME MEASURES: EMMPRIN expression was examined by immunohistochemistry and real-time PCR in ectopic and eutopic endometria. For functional assays, human uterine fibroblasts were treated in the absence or presence of IL-1beta (10 ng/ml) or purified native EMMPRIN (0.5 or 1 microg/ml) for 24 h. Cellular RNA and conditioned medium were assayed by real-time PCR or immunoblotting. RESULTS: EMMPRIN protein localized to epithelial and fibroblast cells of eutopic and ectopic endometria. The pattern of localization was regulated by ovarian hormones. EMMPRIN mRNA levels varied throughout the menstrual cycle in parallel with the cyclic changes in estradiol. EMMPRIN treatment (0.5 microg/ml) of human uterine fibroblast cells stimulated MMP-1 (5.23-fold) and MMP-2 (8.55-fold), but not MMP-3, mRNA levels over levels in control cells (P < 0.05). EMMPRIN treatment (1 microg/ml) stimulated endogenous EMMPRIN (1.6-fold) mRNA levels (P > 0.05). IL-1beta stimulated MMP-1 (5.6-fold), MMP-2 (2.8-fold), and MMP-3 (75-fold) gene expression, but not EMMPRIN, over levels in control cells (P < 0.05). Both EMMPRIN and IL-1beta treatments stimulated MMP-1, -2, and -3, but not EMMPRIN protein secretion, with 0.5 microg/ml producing the greatest response. CONCLUSIONS: The ability of EMMPRIN to stimulate MMP secretion by endometrial fibroblasts indicates its potential role in uterine remodeling and the pathogenesis of endometriosis.

Basigin↗