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Serum sclerostin as a potential novel biomarker for heart valve calcification in patients with chronic kidney disease. EUROPEAN REVIEW FOR MEDICAL AND PHARMACOLOGICAL SCIENCES 2019; 22:8822-8829. [PMID: 30575924 DOI: 10.26355/eurrev_201812_16650] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
OBJECTIVE To explore the correlation between change in sclerostin level and heart valve calcification in patients with chronic kidney disease (CKD) in stages 3-5, as well as the possible underlying mechanism, which could provide a clinical reference for the diagnosis and treatment of cardiovascular disease (CVD). PATIENTS AND METHODS 110 patients were divided into a healthy control group and three groups of patients with CKD stages 3, 4, and 5 according to CKD staging guidelines. Scr, BUN, AKP, TC, TG, HDL, LDL, Ca, Pi, and CRP were measured, and calcium-phosphate product (Ca×Pi) calculated. ELISA was used to measure the sclerostin level, and the estimated glomerular filtration rate (eGFR) was calculated by MDRD. Heart valve calcification was measured by a physician in the Cardiac Department of our hospital. The correlations between sclerostin-level change and heart valve calcification, as well as each index in CKD patients in stages 3-5, were analyzed. RESULTS Compared with the healthy control group, the serum Ca in CKD stage-3, stage-4, and stage-5 groups (p < 0.05) was reduced, and PTH was increased (p < 0.05). Blood Pi and Ca×Pi in the stage-4 and stage-5 groups were increased (p < 0.05). The serum sclerostin level increased with renal hypofunction in stage-3 CKD patients, and was significantly increased compared with that of the control group, reaching the highest level in the terminal stage (p < 0.01). Pearson correlation analysis indicated that serum sclerostin was negatively correlated with eGFR (r = -0.91, p < 0.001) and blood Ca (r= -0.271, p < 0.001), and positively correlated with SCr (r = 0.608, p < 0.001), blood Pi level (r = 0.295, p < 0.001), PTH (r = 0.334, p < 0.001), and Ca×Pi (r = 0.275, p < 0.001). The rate of heart valve calcification in the CKD patients in stage 5 was relatively high (11/30, 36.67%), and significantly higher than that in healthy controls (1/20, 5%; p < 0.01). Logistic regression analysis of heart valve calcification indicated that sclerostin was a risk factor for heart valve calcification in CKD patients in stages 3-5. CONCLUSIONS The sclerostin level gradually increased with renal hypofunction in CKD patients in stages 3-5, and the increase in serum sclerostin level in the CKD patients occurred earlier than the change in Pi and Ca×Pi. The risk of heart valve calcification in stage-5 CKD patients was significantly increased. Sclerostin is an independent risk factor for heart valve calcification in CKD patients.
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Diazoxide induces endoplasmic reticulum stress-related neuroprotection mediated by p38 MAPK against Aβ25-35 insults. EUROPEAN REVIEW FOR MEDICAL AND PHARMACOLOGICAL SCIENCES 2019; 22:6133-6138. [PMID: 30280801 DOI: 10.26355/eurrev_201809_15953] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
OBJECTIVE The endoplasmic reticulum (ER) -resident caspase-12 was identified as a mediator of Aβ neurotoxicity. Recent evidence indicates that mitochondrial ATP-sensitive potassium (KATP) channel openers mediate their neuroprotective role by adjusting ER stress pathways, but the molecular details remain largely unknown and have been investigated. MATERIALS AND METHODS In this study, the protein expression levels of calreticulin (CRT) and caspase-12 activation and phosphorylated p38 MAPK were observed by immunoblotting in cultured PC12 cells from different groups: treatment with Aβ25-35 (group Aβ25-35), treatment with diazoxide (group diazoxide), pretreatment with diazoxide and then exposure to Aβ25-35 (group diazoxide + Aβ25-35), pretreatment with p38 MAPK inhibitor SB 203580 and then exposure to diazoxide and Aβ25-35 (group SB 203580 + diazoxide + Aβ25-35), and the control (group control). RESULTS In response to the treatment with Aβ25-35 (10 µM) for 24 h, the protein expression levels of CRT and caspase-12 activation were increased and phosphorylated p38 MAPK was decreased significantly. Diazoxide reduced CRT overexpression and caspase-12 activation and increased the up-regulation of phosphorylated p38 MAPK. When SB 203580 was presented before exposure to diazoxide and Aβ25-35, CRT expression was markedly suppressed, and the inhibition effect of diazoxide on caspase-12 activation was almost eliminated. CONCLUSIONS We showed that diazoxide induced ERS-related neuroprotection mediated by p38 MAPK against Aβ25-35 insults. From the clinical point of view, these results are of considerable importance for the understanding of AD pathogenesis. However, further studies are required to explore more detailed mechanisms of the observed effects.
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Gene expressions levels of 14-3-3a, NKCCla, A PO-14, and Na +-K +-ATPaseβ in gill tissue of Mugil cephalus acclimated to low salinity. GENETICS AND MOLECULAR RESEARCH 2017; 16:gmr-16-01-gmr.16019444. [PMID: 28218786 DOI: 10.4238/gmr16019444] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
Fishes adapt to salinity changes primarily through osmotic pressure regulation, a process often associated with several genes, including 14-3-3a, NKCCla, APO-14, and Na+-K+-ATPaseβ. The present study investigated the differential expression of genes 14-3-3a, NKCCla, APO-14, and Na+-K+-ATPaseβ in the gill tissue of Mugil cephalus acclimated to low salinity. Susceptibility relationships between the four gene expressions levels and salinity were detected and analyzed using polymerase chain reaction-restriction fragment length polymorphism. Homology analysis results indicated significant differences in the correlation between gene expression and salinity. Under low-salt conditions, expression levels for genes Na+-K+-ATPaseβ and NKCC1a were significantly elevated (P < 0.05), whereas those of genes 14-3-3a and APO-14 were significantly reduced (P < 0.05). Thus, when compared to 14-3-3a and APO-14, Na+-K+-ATPaseβ, and NKCC1a may be better suited to promoting the development of osmotic-regulation mechanisms and increased resistance to environmental stress under low-salt conditions. Furthermore, Na+-K+-ATPaseβ and NKCC1a were identified as suitable potential molecular biomarkers for regulating and controlling genes in low-salinity aquatic environments.
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Novel folliculin (FLCN) mutation and familial spontaneous pneumothorax. QJM 2017; 110:23-26. [PMID: 27486260 DOI: 10.1093/qjmed/hcw109] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/29/2016] [Revised: 06/21/2016] [Indexed: 01/01/2023] Open
Abstract
BACKGROUND Familial spontaneous pneumothorax is one of the characteristics of Birt-Hogg-Dubé syndrome (BHDS), which is an autosomal dominant disease caused by the mutation of folliculin (FLCN). AIM To investigate the mutation of FLCN gene in a familial spontaneous pneumothorax. DESIGN Prospective case study. METHODS Clinical and genetic data of a Chinese family with four patients who presented spontaneous pneumothorax in the absence of skin lesions or renal tumors were collected. CT scan of patient's lung was applied for observation of pneumothorax. DNA sequencing of the coding exons (4-14 exons) of FLCN was performed for all 11 members of the family and 100 unrelated healthy controls. RESULTS CT scan of patient's lung showed spontaneous pneumothorax. A mutation (c. 510C > G) that leads to a premature stop codon (p. Y170X) was found in the proband using DNA sequencing of coding exons (4-14 exons) of FLCN. This mutation was also observed in the other affected members of the family. CONCLUSIONS A nonsense mutation of FLCN was found in a spontaneous pneumothorax family. Our results expand the mutational spectrum of FLCN in patients with BHDS.
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Implantation of muscle satellite cells overexpressing myogenin improves denervated muscle atrophy in rats. Braz J Med Biol Res 2016; 49:e5124. [PMID: 26871970 PMCID: PMC4742975 DOI: 10.1590/1414-431x20155124] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2015] [Accepted: 10/08/2015] [Indexed: 11/22/2022] Open
Abstract
This study evaluated the effect of muscle satellite cells (MSCs) overexpressing myogenin (MyoG) on denervated muscle atrophy. Rat MSCs were isolated and transfected with the MyoG-EGFP plasmid vector GV143. MyoG-transfected MSCs (MTMs) were transplanted into rat gastrocnemius muscles at 1 week after surgical denervation. Controls included injections of untransfected MSCs or the vehicle only. Muscles were harvested and analyzed at 2, 4, and 24 weeks post-transplantation. Immunofluorescence confirmed MyoG overexpression in MTMs. The muscle wet weight ratio was significantly reduced at 2 weeks after MTM injection (67.17±6.79) compared with muscles injected with MSCs (58.83±5.31) or the vehicle (53.00±7.67; t=2.37, P=0.04 and t=3.39, P=0.007, respectively). The muscle fiber cross-sectional area was also larger at 2 weeks after MTM injection (2.63×10³±0.39×10³) compared with MSC injection (1.99×10³±0.58×10³) or the vehicle only (1.57×10³±0.47×10³; t=2.24, P=0.049 and t=4.22, P=0.002, respectively). At 4 and 24 weeks post-injection, the muscle mass and fiber cross-sectional area were similar across all three experimental groups. Immunohistochemistry showed that the MTM group had larger MyoG-positive fibers. The MTM group (3.18±1.13) also had higher expression of MyoG mRNA than other groups (1.41±0.65 and 1.03±0.19) at 2 weeks after injection (t=2.72, P=0.04). Transplanted MTMs delayed short-term atrophy of denervated muscles. This approach can be optimized as a novel stand-alone therapy or as a bridge to surgical re-innervation of damaged muscles.
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Successful microsurgical replantation of a child's completely amputated ear. J Plast Reconstr Aesthet Surg 2008; 61:e19-22. [PMID: 17901008 DOI: 10.1016/j.bjps.2007.07.010] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2006] [Revised: 01/22/2007] [Accepted: 07/12/2007] [Indexed: 11/18/2022]
Abstract
SUMMARY We present a case of a 9-year old boy who underwent successful replantation of a completely amputated ear. Few reports have been published on replantation of children's ears that are completely avulsed. Venous drainage is a well-known factor contributing to the failure of completely amputated ear replantation. In this case, we used a technique of transillumination to examine the amputated ear, and selected veins for exploration. Finally, a suitable vein was found and anastomosed to the one on the recipient side. The ear seemed to be completely viable once the problems of arterial blood supply and venous drainage were solved. A 4-year follow-up was conducted, and the result was satisfactory. The technique of transillumination is recommended in similar cases to solve the problem of venous drainage and to improve the survival rate of replanted ears.
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Transcatheter closure of large fistula between left main coronary artery and right atrium using Amplatzer duct occluder. Heart 2003; 89:772. [PMID: 12807854 PMCID: PMC1767709 DOI: 10.1136/heart.89.7.772] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/03/2022] Open
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c-Jun potentiates the functional interaction between the amino and carboxyl termini of the androgen receptor. J Biol Chem 2001; 276:44704-11. [PMID: 11577103 DOI: 10.1074/jbc.m107346200] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The transactivation functions of the human androgen receptor (hAR) are regulated by several accessory factors that can be either positive or negative. One factor that has been previously shown to mediate hAR transactivation is the proto-oncoprotein c-Jun. The positive effect is a primary one, can be exerted by both endogenous and exogenous c-Jun, and requires multiple regions of c-Jun. However, the exact mechanism by which c-Jun exerts its enhancing function is unknown. In this study, we have used a mammalian two-hybrid system to ask if c-Jun influences the ligand-dependent amino- to carboxyl-terminal (N-to-C) interaction of hAR, which is thought to be responsible for the homodimerization of this receptor. Our results show that c-Jun enhances both hAR N-to-C terminal interaction and DNA binding in vitro. We have also tested a panel of c-Jun and c-Fos mutants for their activities on the N-to-C interaction, and the data demonstrate that the activities of these mutants parallel their activities on hAR transactivation. A mutation in the hAR activation function-2 (AF-2) abrogates N-to-C interaction, DNA binding, and transactivation, and these activities are not rescued by exogenous c-Jun. Interestingly, the p160 coactivator TIF2 can stimulate hAR N-to-C interaction, a finding consistent with the effect on hAR transactivation. These data strongly suggest that the hAR N-to-C interaction is the target of c-Jun action, and this activity requires a functional receptor AF-2.
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[Clinical evaluation of intermittent strophanthin K therapy for congestive heart failure combined coronary artery disease]. HUNAN YI KE DA XUE XUE BAO = HUNAN YIKE DAXUE XUEBAO = BULLETIN OF HUNAN MEDICAL UNIVERSITY 2001; 26:448-50. [PMID: 12536498] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/28/2023]
Abstract
OBJECTIVE To evaluate the effects and safety of intermittent strophanthin K therapy (ISKT) for congestive heart failure combined coronary artery disease with sinus rhythm. METHODS Two hundred patients divided into Group A (98 cases with maintenance digoxin therapy) and Group B (102 cases with ISKT). They were studied for 3 months and some of them for longer period. RESULTS Comparing the pretreatment data: 1. heart rate (HR, bpm), 2. left ventricular ejection fraction (LVEF), 3. blood pressure (Bp, mmHg, calculated values as mean Bp for statistics). In group A, item 1. and 2. were significantly improved (item 1. 88 +/- 12 and 68 +/- 12, P < 0.01; item 2. 0.32 +/- 0.12 and 0.40 +/- 0.12, P < 0.01; item 3. showed no significant difference (126 +/- 21/90 +/- 6 and 128 +/- 21/80 +/- 5, P > 0.05). In group B, item 1., 2. and 3. were significantly improved (item 1. 90 +/- 10 and 70 +/- 11, item 2. 0.32 +/- 0.10 and 0.45 +/- 0.10, item 3. 128 +/- +/- 20/91 +/- 7 and 110 +/- 10/76 +/- 10, the p valves are the same < 0.01). As compared with the posttreatment data of both group A and B, HR, P > 0.05, there was no significant difference, LVEF, P < 0.05, there was significant difference, Bp, P < 0.01, there was significant difference. It showed no significant difference in total occurrence rate of digitalis overload or toxication between two groups also. CONCLUSION ISKT for congestive heart failure combined coronary artery disease with sinus rhythm is effective and safe, with better improvement of heart function and Bp level.
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Regulation of transcription by AMP-activated protein kinase: phosphorylation of p300 blocks its interaction with nuclear receptors. J Biol Chem 2001; 276:38341-4. [PMID: 11518699 DOI: 10.1074/jbc.c100316200] [Citation(s) in RCA: 165] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
AMP-activated protein kinase (AMP-kinase) modulates many metabolic processes in response to fluctuations in cellular energy status. Although most of its known targets are metabolic enzymes, it has been proposed that AMP-kinase might also regulate gene expression. Here we demonstrate that the transcriptional coactivator p300 is a substrate of AMP-kinase. Phosphorylation of p300 at serine 89 by AMP-kinase dramatically reduced its interaction, in vitro and in vivo, with the nuclear receptors peroxisome proliferator-activated receptor gamma, thyroid receptor, retinoic acid receptor, and retinoid X receptor, but did not affect its interaction with the non-nuclear receptor transcription factors E1a, p53, or GATA4. These findings indicate that the AMP-kinase signaling pathway selectively modulates a subset of p300 activities and represent the first example of a transcriptional component regulated by AMP-kinase. Our results suggest a direct link between cellular energy metabolism and gene expression.
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[Effects of percutaneous transluminal coronary angioplasty and stenting on QT dispersion in patients with coronary heart disease]. HUNAN YI KE DA XUE XUE BAO = HUNAN YIKE DAXUE XUEBAO = BULLETIN OF HUNAN MEDICAL UNIVERSITY 2001; 26:171-2. [PMID: 12536661] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/28/2023]
Abstract
OBJECTIVE The aim of this study was to approach the effects of percutaneous transluminal coronary angioplasty (PTCA) and stenting on QT dispersion (QTd) in patients with coronary heart disease. METHODS PTCA and stenting were performed successfully on 42 patients with coronary heart disease. QTd and corrected QTd (QTcd) were obtained with a standard 12-lead ECG before and after PTCA + Stent. RESULTS QTd and QTcd after PTCA + Stent were reduced significantly compared to those before PTCA + Stent (P < 0.01). There were no significant difference in QTd and QTcd before PTCA + Stent between single vessel lesion and multi-vessel lesion, but after PTCA + Stent, QTd and QTcd in single vessel lesion were decreased significantly compared to those in multi-vessel lesion. The ventricular arrhythmia in 9 patients was over after PTCA + Stent. CONCLUSIONS QTd and QTcd were decreased significantly after PTCA + Stent because of the improvement of myocardial ischemia and heterogeneous repolarization in patients with coronary heart disease. The degree in decreasing QTd and QTcd was associated with compensatory circulation in coronary artery.
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[A study on thermal decomposition mechanism and quality analysis of pearl powder]. ZHONGGUO ZHONG YAO ZA ZHI = ZHONGGUO ZHONGYAO ZAZHI = CHINA JOURNAL OF CHINESE MATERIA MEDICA 2000; 25:518-20. [PMID: 12516459] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/28/2023]
Abstract
OBJECTIVE To establish a rapid and convenient method for distinguishing genuine from sham of pearl powder as well as appraising its quality preliminarily. METHOD Thermogravimetry and differential thermogravimetry. RESULT The TG and DTG curves can be divided into two characteristic regions. The first step ranges from 250 to 380 degrees C with a weight loss of about 3%, resulting from the denaturalization and decomposition of organic matter in the powder; and the second step from 600 to 780 degrees C with a weight loss of about 40% resulting from the decomposition of calcium carbonate in the powder. CONCLUSION According to the two characteristic regions on TG and DTG curves along with corresponding parameters, pearl powder can be appropriately authenticated. Being related directly to the contents of organic matter in pearl powder, the first step is an important criterion for quality appraisal.
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c-Jun targets amino terminus of androgen receptor in regulating androgen-responsive transcription. Endocrine 2000; 13:55-62. [PMID: 11051047 DOI: 10.1385/endo:13:1:55] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/20/2000] [Revised: 05/03/2000] [Accepted: 05/03/2000] [Indexed: 11/11/2022]
Abstract
The human androgen receptor (hAR) is a member of the nuclear receptor superfamily and functions as a ligand-inducible transcription factor. We have previously proposed that c-Jun mediates the transcriptional activity of this receptor. The modular nature of hAR was used in this study to generate several fusions with the heterologous DNA-binding domain of the yeast transcription factor GAL4 in an attempt to identify the c-Jun-responsive domains within the receptor. Our results suggest that the target of c-Jun action is the amino terminus (AB region) of the receptor and that hAR amino acids 502-521 are critical for the c-Jun response. Additionally, amino acids 503-555 were shown to harbor an autonomous transactivation that is stimulated by c-Jun. Furthermore, we demonstrated that transcription intermediary factor-2 (TIF-2), a coactivator that acts on the activation function-2, stimulates the full-length hAR. These results suggest that c-Jun and TIF-2 can work together as coactivators on the hAR by targeting distinct portions of the receptor.
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Abstract
Upon binding retinoic acid (RA), the retinoic acid receptors (RARs) are able to positively and negatively regulate transcription. It has been shown that the DNA-binding domain and carboxy terminus of RARs are necessary for the ligand-dependent ability of the receptor to repress AP-1 transcriptional activity. A fusion of these two regions, shown to constitutively inhibit AP-1 activity, was used in a yeast two-hybrid screen to identify a novel hRARalpha-interacting protein. This protein, hsRPB7, a subunit of RNA polymerase II, interacts with hRARalpha in the absence of RA and addition of RA disrupts the interaction. Truncation analysis indicates that hsRPB7 specifically interacts with the hRARalpha DNA-binding domain. This interaction appears to compromise transcription, since overexpressed hRARalpha, in the absence of RA, is able to repress the activity of several RNA polymerase II-dependent activators, including AP-1 and the glucocorticoid receptor. This repression is relieved by transfected hsRPB7, strongly suggesting that ligand-free hRARalpha can block AP-1 activity by sequestering hsRPB7. The repression is dependent on the integrity of the hRARalpha DBD, since a mutation within the DBD blocks both the hRARalpha-hsRPB7 interaction and ligand-free hRARalpha repression of AP-1. These results provide evidence that non-liganded hRARalpha can regulate transcription by directly interacting with RNA polymerase II, and thus suggest a novel pathway by which hRARalpha can cross-talk with AP-1 and perhaps other families of transcriptional activators.
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Ligand-activated retinoic acid receptor inhibits AP-1 transactivation by disrupting c-Jun/c-Fos dimerization. Mol Endocrinol 1999; 13:276-85. [PMID: 9973257 DOI: 10.1210/mend.13.2.0237] [Citation(s) in RCA: 61] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
In the presence of retinoic acid (RA), the retinoid receptors, retinoic acid receptor (RAR) and retinoid X receptor (RXR), are able to up-regulate transcription directly by binding to RA-responsive elements on the promoters of responsive genes. Liganded RARs and RXRs are also capable of down-regulating transcription, but, by contrast, this is an indirect effect, mediated by the interaction of these nuclear receptors not with DNA but the transcription factor activating protein-1 (AP-1). AP-1 is a dimeric complex of the protooncoproteins c-Jun and c-Fos and directly regulates transcription of genes important for cellular growth. Previous in vitro results have suggested that RARs can block AP-1 DNA binding. Using a mammalian two-hybrid system, we report here that human RARalpha (hRARalpha) can disrupt in a RA-dependent manner the homo- and heterodimerization properties of c-Jun and c-Fos. This inhibition of dimerization is cell specific, occurring only in those cells that exhibit RA-induced repression of AP-1 transcriptional activity. Furthermore, this mechanism appears to be specific for the RARs, since another potent inhibitor of AP-1 activity, the glucocorticoid receptor, does not affect AP-1 dimerization. Our data argue for a novel mechanism by which RARs can repress AP-1 DNA binding, in which liganded RARs are able to interfere with c-Jun/c-Jun homodimerization and c-Jun/c-Fos heterodimerization and, in this way, may prevent the formation of AP-1 complexes capable of DNA binding.
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c-Fos dimerization with c-Jun represses c-Jun enhancement of androgen receptor transactivation. Endocrine 1998; 9:193-200. [PMID: 9867253 DOI: 10.1385/endo:9:2:193] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/10/1998] [Revised: 06/22/1998] [Accepted: 06/22/1998] [Indexed: 11/11/2022]
Abstract
The transcriptional activity of the human androgen receptor (hAR), like other nuclear receptors, is dependent on accessory factors. One such factor is c-Jun, which has been shown to have a selective function of mediating androgen receptor-dependent transactivation. This c-Jun activity is inhibited by c-Fos, another protooncoprotein that can dimerize with c-Jun to form the transcription factor AP-1. Here we show that c-jun mediates hAR-induced transactivation from the promoter of the androgen-regulated gene, human kallikrein-2 (hKLK2), and c-Fos blocks this activity. Using c-Fos truncation mutants and measuring hKLK2-dependent transcription, we have determined that the bZIP region of c-Fos is required and sufficient for inhibiting c-Jun enhancement of hAR transactivation. Further truncation analysis of the bZIP shows that the c-Fos dimerization function, mediated through the leucine zipper, is essential for the negative activity, whereas DNA binding, mediated through the basic region, is dispensable. These results suggest that heterodimerization by c-Fos with c-Jun blocks c-Jun's ability to enhance hAR-induced transactivation.
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Abstract
The proto-oncoprotein c-Jun forms as a heterodimer with c-Fos, the transcription factor AP-1. AP-1 regulates transcription through transactivation, a process requiring DNA binding. Here we report an indirect mechanism by which c-Jun can regulate transcription via the androgen receptor. In this process, c-Jun is able to support androgen receptor-mediated transactivation in the absence of an interaction with c-Fos or any apparent DNA binding. This positive effect of c-Jun was dose-dependent. Both exogenously added and endogenously induced c-Jun are able to act on the androgen receptor. Transactivation by the androgen receptor can undergo self-squelching, and this was relieved by transfected c-Jun. Using a time-course experiment, we provide evidence that the c-Jun effect is primary. c-Fos is able to block human androgen receptor activity in both the absence and presence of transfected c-Jun. Using a modified form of the yeast two-hybrid system, we show in Cos cells that c-Jun can interact with the DNA binding domain/hinge region (CD regions) of the androgen receptor. Therefore, we propose that c-Jun functions as a mediator for androgen receptor-induced transactivation.
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The dimerization interfaces formed between the DNA binding domains of RXR, RAR and TR determine the binding specificity and polarity of the full-length receptors to direct repeats. EMBO J 1994; 13:1425-33. [PMID: 8137826 PMCID: PMC394960 DOI: 10.1002/j.1460-2075.1994.tb06396.x] [Citation(s) in RCA: 174] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
Heterodimers of retinoid X receptor (RXR) and retinoic acid receptor (RAR) bind preferentially to directly repeated elements with spacing of two (DR2) or five (DR5) base pairs, due to the specific heterocooperative interaction of their DNA binding domains (DBDs) on these elements. We have demonstrated in the accompanying paper that the heterodimeric DBD interface that is responsible for the cooperative binding to DR5 elements, specifically involves the D-box of the RXR CII finger and the tip of the RAR CI finger. We show here that a second type of dimerization interface, which specifically implicates the RAR T-box and the RXR CII finger to the exclusion of the D-box, determines the selective binding to DR2 elements. Interestingly, the same type of dimerization interface (RXR T-box and CII finger) is responsible for the cooperative binding of homodimers of the RXR DBD to DR1 elements. Based on the three-dimensional structure of the glucocorticoid receptor DBD, modeling of RXR/RAR, RXR/TR and RXR/RXR DBD cooperative interactions predicts that in all cases the DBD contributing the CII finger, i.e. that of RXR, has to be positioned 5' to its cooperatively bound partner. This binding polarity of the DBDs is conferred upon the full-length receptors, since crosslinking experiments indicate that RXR is always 5' to RAR in complexes between either DR5 or DR2 and RXR/RAR heterodimers. The possible significance of these observations for transactivation by retinoic acid receptors is discussed.
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Dimerization interfaces formed between the DNA binding domains determine the cooperative binding of RXR/RAR and RXR/TR heterodimers to DR5 and DR4 elements. EMBO J 1994; 13:1414-24. [PMID: 8137825 PMCID: PMC394959 DOI: 10.1002/j.1460-2075.1994.tb06395.x] [Citation(s) in RCA: 137] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
We have previously reported that the binding site repertoires of heterodimers formed between retinoid X receptor (RXR) and either retinoic acid receptor (RAR) or thyroid hormone receptor (TR) bound to response elements consisting of directly repeated PuG(G/T)TCA motifs spaced by 1-5 bp [direct repeat (DR) elements 1-5] are highly similar to those of their corresponding DNA binding domains (DBDs). We have now mapped the dimerization surfaces located in the DBDs of RXR, RAR and TR, which are responsible for cooperative interaction on DR4 (RXR and TR) and DR5 (RXR and RAR). The D-box of the C-terminal CII finger of RXR provides one of the surfaces which is specifically required for the formation of the heterodimerization interfaces on both DR4 and DR5. Heterodimerization with the RXR DBD on DR5 specifically requires the tip of the RAR CI finger as the complementary surface, while a 7 amino acid sequence encompassing the 'prefinger region', but not the TR CI finger, is specifically required for efficient dimerization of TR and RXR DBDs on DR4. Importantly, DBD swapping experiments demonstrate not only that the binding site repertoires of the full-length receptors are dictated by those of their DBDs, but also that the formation of distinct dimerization interfaces between the DBDs are the critical determinants for cooperative DNA binding of these receptors to specific DRs.
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[Comparative study of single-point method and multipoint method in the measurement of estrogen receptor and progesterone receptor in breast cancer]. ZHONGHUA ZHONG LIU ZA ZHI [CHINESE JOURNAL OF ONCOLOGY] 1992; 14:112-5. [PMID: 1618078] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
A comparative study of estrogen receptor (ER) and progesterone receptor (PgR) by single-point method and multi-point method in dextran coated charcoal assay (DCC) was carried out in 50 and 47 cases of breast cancer, respectively. Taking 10 fmol/mg protein as the positive value, the conformation rate of both methods in ER measurement was 96.0% (48/50) with r = 0.978 by linear regression analysis (P less than 0.001). In PgR measurement, the conformation rate of both methods was 95.7% with r = 0.988 (P less than 0.001). Statistically, the difference between single-point method and multi-point method in the ER and PgR measurements was not significant (P greater than 0.5) both in rank-sum test and in paired t-test. The authors suggest that ER and PgR of breast cancer samples be measured with single-point method for its simplicity and less tumor tissue required.
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