Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:2.5.1.18 (glutathione S-transferase)
22,582 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The androgen receptor (AR) is a ligand-dependent transcription factor that has an essential role in the normal growth, development, and maintenance of the prostate gland. The AR is part of a large family of steroid receptors that also includes the glucocorticoid, progesterone, and mineralocorticoid receptors. Steroid receptor family members share significant homology at their DNA and ligand-binding domains. However, these receptors exhibit a high degree of sequence variability at their NH(2)-terminal domain, which suggests the possibility of receptor-specific interactions with co-regulator proteins. Transcriptional co-regulators that interact with the AR may have a role in defining AR activity and may be involved in directing AR-specific responses. Here we have identified Ran-binding protein in the microtubule-organizing center (RanBPM) to be a novel AR-interacting protein by yeast two-hybrid assay and have confirmed this interaction by glutathione S-transferase- and His-tagged pull-down assays. In addition, transient overexpression of RanBPM in prostate cancer cell lines resulted in enhanced AR activity in a ligand-dependent fashion. Glucocorticoid receptor activity was also enhanced when RanBPM was overexpressed, whereas estrogen receptor activity remained unchanged. These data demonstrate that RanBPM interacts with steroid receptors to selectively modify their activity.
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PMID:RanBPM, a nuclear protein that interacts with and regulates transcriptional activity of androgen receptor and glucocorticoid receptor. 1236 45

Activating signal cointegrator 1 (ASC-1) has been recently reported as a coactivator of some nuclear receptors. In the present study, we have analyzed the expression of ASC-1 in the mouse testis and investigated its capacity to modulate the transcriptional activity of androgen receptor (AR). We found that although ASC-1 mRNA was ubiquitously expressed at a low level in mouse tissues, a couple of testis-specific mRNAs were expressed in the adult testis. Cloning of one testis-specific variant revealed that the ubiquitous and testis-specific transcripts of ASC-1 share at least the same open reading frame. The expression of the testis-specific ASC-1 mRNAs was developmentally regulated, and the onset of their expression coincided with the initiation of spermatogenesis. In situ hybridization of mouse testis with ASC-1 antisense probe demonstrated predominant expression of ASC-1 in the interstitial Leydig cells that express AR. Moreover, yeast two-hybrid tests and glutathione S-transferase pull-down assays revealed that ASC-1 associates directly with AR and that the hinge domain of AR and a putative zinc-finger motif of ASC-1 are major determinants for their interaction. Transient transfection assays performed by expressing ASC-1 in combination with AR and an androgen-responsive reporter gene showed that ASC-1 moderately alters the induction of the reporter gene. Taken together, these results suggest that ASC-1 may function as an AR coregulator and have a role in testicular functions.
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PMID:Activating signal cointegrator 1 is highly expressed in murine testicular Leydig cells and enhances the ligand-dependent transactivation of androgen receptor. 1239 Aug 91

APPL may function as an adapter protein to modulate the phosphatidylinositol 3-kinase (PI3K)/Akt pathway. Although we have previously proven that the PI3K/Akt pathway can suppress androgen receptor (AR) transactivation, the potential linkage from APPL to the AR remains unclear. Here we demonstrated that APPL could suppress AR-mediated transactivation in a dose-dependent manner in LNCaP and PC-3 cells. This suppressive effect could be blocked by either dominant-negative Akt or dominant-negative PI3K or LY294002, suggesting that the APPL-mediated suppression of AR transactivation is dependent on the PI3K/Akt pathway. We also observed that APPL could further enhance the Akt-mediated suppression of AR transactivation and AR target gene using the reporter gene and Northern blot assay. APPL was able to enhance insulin-like growth factor (IGF-1)-mediated Akt activation. The abrogation of IGF-1-mediated Akt activation by the dominant-negative PI3K or LY294002 or antisense APPL suggests that APPL may function as an important adapter protein in controlling the IGF-1 --> Akt signal pathway. Co-immunoprecipitation and glutathione S-transferase pull-down assays suggest that APPL, Akt, and AR may exist in a complex and Akt may serve as an important bridge factor for the association of APPL with AR. Together, our data indicate that APPL may suppress AR transactivation via potentiating Akt activity.
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PMID:APPL suppresses androgen receptor transactivation via potentiating Akt activity. 1262 Oct 49

Four and a half LIM domain (FHL) proteins are members of the LIM protein superfamily. Several FHL proteins function as co-activators of CREM/CREB transcription factors and the androgen receptor. FHL3 is highly expressed in skeletal muscle, but its function is unknown. FHL3 localized to the nucleus in C2C12 myoblasts and, following integrin engagement, exited the nucleus and localized to actin stress fibers and focal adhesions. In mature skeletal muscle FHL3 was found at the Z-line. Actin was identified as a potential FHL3 binding partner in yeast two-hybrid screening of a skeletal muscle library. FHL3 complexed with actin both in vitro and in vivo as shown by glutathione S-transferase pull-down assays and co-immunoprecipitation of recombinant and endogenous proteins. FHL3 promoted cell spreading and when overexpressed in spread C2C12 cells disrupted actin stress fibers. Increased FHL3 expression was detected in highly motile cells migrating into an artificial wound, compared with non-motile cells. The molecular mechanism by which FHL3 induced actin stress fiber disassembly was demonstrated by low speed actin co-sedimentation assays and electron microscopy. FHL3 inhibited alpha-actinin-mediated actin bundling. These studies reveal FHL3 as a significant regulator of actin cytoskeletal dynamics in skeletal myoblasts.
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PMID:FHL3 is an actin-binding protein that regulates alpha-actinin-mediated actin bundling: FHL3 localizes to actin stress fibers and enhances cell spreading and stress fiber disassembly. 1270 94

Early studies suggested that the signature motif, LXXLL, within steroid hormone receptor p160 coregulators may play important roles for the mediation of receptor-coregulator interaction. Interestingly, several androgen receptor (AR) coregulators, such as ARA70 and ARA55, may not use such a unique motif to mediate their coregulator activity. Here we apply the phage display technique to identify some new signature motifs, (F/W)XXL(F/W) and FXXLY (where F is phenylalanine, W is tryptophan, L is leucine, Y is tyrosine, and X is any amino acid) that can influence the interaction between AR and AR coregulators. Sequence analyses found that several AR coregulators, such as ARA70, ARA55, ARA54, and FHL2, contain FXXL(F/Y) motifs. Both glutathione S-transferase pull-down assays and transient transfection reporter assays demonstrate that these AR coregulators may use the FXXL(F/Y) motif to interact with AR and exert their AR coregulator activity. Exchanging the amino acid of Phe, Trp, or Tyr in this newly identified signature motif cluster may influence these peptides to interact with AR. The motif-containing peptides, as well as ARA70 or ARA54, may require selective flanking sequences for the better interaction with AR. In addition to influencing the AR transactivation, these motifs in AR-interacting peptides/proteins were also able to influence the AR N-/C-terminal interaction. Together, our data suggest that AR interacting peptides and/or AR coregulators may utilize the (F/W)XXL(F/W) and FXXLY motifs to mediate their interaction with AR and exert their influences on the AR transactivation.
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PMID:The use of phage display technique for the isolation of androgen receptor interacting peptides with (F/W)XXL(F/W) and FXXLY new signature motifs. 1271 4

T cell factor (Tcf) proteins bind beta-catenin and are downstream effectors of Wnt/beta-catenin signals. A recently demonstrated interaction between beta-catenin and the androgen receptor (AR) ligand binding domain has suggested that AR may be a Tcf-independent Wnt/beta-catenin effector. This study demonstrates that there is a direct interaction between the AR DNA binding domain (DBD) and Tcf4. Tcf4 bound specifically to a glutathione S-transferase-ARDBD fusion protein and could be coimmunoprecipitated with beta-catenin and transfected AR or endogenous AR in prostate cancer cells. Transfected Tcf4 repressed the transcriptional activity of full-length AR and a VP16-ARDBD fusion protein, and this repression was only partially reversed by transfected beta-catenin. AR activation by cyproterone acetate, a partial agonist that did not support beta-catenin binding to the AR, was also repressed by Tcf4, further indicating that repression was not due to beta-catenin sequestration. Tcf4 could recruit beta-catenin to the AR DBD in vitro and to the cyproterone acetate-liganded AR in vivo. Chromatin immunoprecipitation experiments in LNCaP prostate cancer cells showed that endogenous AR was bound to a Tcf4-responsive element in the c-myc promoter. These findings indicate that AR and Tcf4 can interact directly and that this interaction may occur on the promoters or enhancers of particular genes. The direct AR-Tcf4 interaction, in conjunction AR- and Tcf4-beta-catenin binding, provides a mechanism for cooperative and selective gene regulation by AR and the Wnt/beta-catenin-Tcf pathway that may contribute to normal and neoplastic prostate growth.
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PMID:A direct beta-catenin-independent interaction between androgen receptor and T cell factor 4. 1279 78

The methylation status of 7 genes was examined in four cell lines, 36 samples of benign prostatic hyperplasia (BPH), 20 samples of prostatic intraepithelial neoplasia (PIN) and 109 samples of prostate cancer (PCa), using methylation-specific PCR (MSP): the pi-class glutathione S-transferase (GSTP1), retinoic acid receptor beta 2(RARbeta2), androgen receptor (AR), death-associated protein kinase (DAPK), tissue inhibitor of metalloproteinase-3 (TIMP-3), O(6)-methylguanine DNA methyltransferase (MGMT), and hypermethylated in cancer-1 (HIC-1). The frequencies of methylation in PCa were 88% for GSTP1, 78% for RARbeta2, 36% for DAPK, 15% for AR, 6% for TIMP-3, and 2% for MGMT, whereas the values were 11% for AR and DAPK, 6% for TIMP-3, 3% for GSTP1, and 0 for RARbeta2 and MGMT in BPH. Aberrant methylation of the GSTP1 and RARbeta2 genes was detected in 30% and 20% of PIN, respectively. Most samples of BPH and PCa were positive for HIC-1 methylation. Regarding accumulation of methylated cancer-related genes, there were significant correlations between PCa and BPH as well as PIN and BPH. In the present study, a high frequency of aberrant promoter methylation of the GSTP1 and RARbeta2 genes was noted in PCa. Our findings suggest that methylation of cancer-related genes may be involved in carcinogenesis of the prostate.
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PMID:Altered methylation of multiple genes in carcinogenesis of the prostate. 1284 78

Androgen receptor (AR) that mediates androgen action is a crucial factor in male reproductive functions. Here, we report a novel AR corepressor ARR19 (androgen receptor corepressor-19 kDa), which has been isolated as a putative androgen-induced gene from murine testis. ARR19 encoding a leucine-rich protein is expressed only in male reproductive organs such as testis and prostate. ARR19 expression in the testis is developmentally regulated. Functional analysis conducted by the transient transfection of mammalian cells shows that ARR19 represses AR transactivation in a dose-dependent manner. Furthermore, yeast two-hybrid and glutathione S-transferase pull-down analyses reveal that ARR19 directly associates with AR through the N-terminal and leucine zipper-containing regions of ARR19 and the DNA binding-hinge domain of AR. Interestingly, ARR19 localized in the cytoplasmic compartment cotranslocates into the nucleus with AR upon androgen exposure. The ARR19 repression of AR transactivation is through the recruitment of histone deacetylase 4 (HDAC4) by ARR19. Overexpression of HDAC4 further inhibits the ARR19-repressed AR transactivation. In addition, ARR19 directly interacts with HDAC4 in vitro. Furthermore, DNA-protein complex immunoprecipitation assays reveal that HDAC4 is recruited to an androgen-regulated promoter through ARR19. Taken together, the results suggest that ARR19 may act as an AR corepressor in vivo and play an important role in male reproductive functions.
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PMID:Androgen receptor corepressor-19 kDa (ARR19), a leucine-rich protein that represses the transcriptional activity of androgen receptor through recruitment of histone deacetylase. 1457 37

We examined whether selected polymorphisms in 11 candidate genes and serum levels of insulin-like growth factor I (IGF-I) help predict the presence of prostate cancer among patients prescreened with prostate-specific antigen (PSA) and digital rectal exam (DRE). We studied 1031 consecutive men who underwent one or more prostate biopsies because of an elevated PSA level (>4 ng/ml) or an abnormal DRE. Eleven candidate genes were examined, including the androgen receptor, SRD5A2, CYP17, CYP3A4, vitamin D receptor, PSA, GST-T1, GST-M1, GST-P1, IGF-I, and IGF binding protein 3. We also measured serum IGF-I levels before biopsy. Of the 1031 men, 483 had cancer on any biopsy (cases) and 548 men had no cancer (controls). Age, ethnicity, total PSA, and DRE result were strongly predictive of the presence of prostate cancer. The mean IGF-I level for cases (119.4 ng/ml) was lower than for controls (124.4 ng/ml, P = 0.05) and were not predictive for the presence of prostate cancer. We found no associations between the androgen receptor, SRD5A2, CYP17, CYP3A4, vitamin D receptor, GST-M1, GST-P1, and IGF binding protein 3 genotypes and prostate cancer risk. The adjusted odds ratios for having prostate cancer for patients with the GST-T1 and IGF-I variant alleles were 1.64 (95% confidence interval, 1.1-2.4; P = 0.01) and 1.70 (95% confidence interval, 1.1-2.7; P = 0.02), respectively. Nine of 11 candidate genes were not significantly predictive for prostate cancer in a clinical setting. The GST-T1 and IGF-I polymorphisms demonstrated modest associations with prostate cancer risk. IGF-I levels were not helpful in identifying patients with prostate cancer at the time of biopsy.
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PMID:Comprehensive assessment of candidate genes and serological markers for the detection of prostate cancer. 1469 33

Positive responses to combined androgen elimination therapy and radiation therapy have been well documented in the treatment of prostate cancer patients. The detailed mechanisms how androgen-androgen receptor (AR) cross talks to the radiation-related signal pathways, however, remain largely unknown. Here we report the identification of hRad9, a key member of the checkpoint Rad protein family, as a coregulator to suppress androgen-AR transactivation in prostate cancer cells. In vivo and in vitro interaction assays using Saccharomyces cerevisiae two-hybrid, mammalian two-hybrid, glutathione S-transferase pull-down, and coimmunoprecipitation methods prove that AR can interact with the C terminus of hRad9 via its ligand binding domain. The FXXLF motif within the C terminus of hRad9 interrupts the androgen-induced interaction between the N terminus and C terminus of AR. This interaction between AR and hRad9 may result in the suppression of AR transactivation, demonstrated by the repressed AR transactivation in androgen-induced luciferase reporter assay and the reduced endogenous prostate-specific antigen expression in Western blot assay. Addition of small interfering RNA of hRad9 can reverse hRad9 suppression effects, which suggests that hRad9 functions as a repressor of AR transactivation in vivo. Together, our data provide the first linkage between androgen-AR signals and radiation-induced responses. Further studies of the influence of hRad9 on prostate cancer growth may provide potential new therapeutic approaches.
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PMID:Human checkpoint protein hRad9 functions as a negative coregulator to repress androgen receptor transactivation in prostate cancer cells. 1496 97


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