Publications by authors named "Suxia Bai"

12 Publications

  • Page 1 of 1

Androgen receptor regulation by histone methyltransferase Suppressor of variegation 3-9 homolog 2 and Melanoma antigen-A11.

Mol Cell Endocrinol 2017 03 29;443:42-51. Epub 2016 Dec 29.

Laboratories for Reproductive Biology, Department of Pediatrics, Lineberger Comprehensive Cancer Center, and Department of Biochemistry and Biophysics, University of North Carolina, Chapel Hill, NC 27599, United States. Electronic address:

Androgen receptor (AR) transcriptional activity depends on interactions between the AR NH-terminal region and transcriptional coregulators. A yeast two-hybrid screen of a human testis library using predicted α-helical NH-terminal fragment AR-(370-420) as bait identified suppressor of variegation 3-9 homolog 2 (SUV39H2) histone methyltransferase as an AR interacting protein. SUV39H2 interaction with AR and the AR coregulator, melanoma antigen-A11 (MAGE-A11), was verified in two-hybrid, in vitro glutathione S-transferase affinity matrix and coimmunoprecipitation assays. Fluorescent immunocytochemistry colocalized SUV39H2 and AR in the cytoplasm without androgen, in the nucleus with androgen, and with MAGE-A11 in the nucleus independent of androgen. Chromatin immunoprecipitation using antibodies raised against SUV39H2 demonstrated androgen-dependent recruitment of AR and SUV39H2 to the androgen-responsive upstream enhancer of the prostate-specific antigen gene. SUV39H2 functioned cooperatively with MAGE-A11 to increase androgen-dependent AR transcriptional activity. SUV39H2 histone methyltransferase is an AR coactivator that increases androgen-dependent transcriptional activity through interactions with AR and MAGE-A11.
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http://dx.doi.org/10.1016/j.mce.2016.12.028DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5303141PMC
March 2017

Live imaging of endogenous PSD-95 using ENABLED: a conditional strategy to fluorescently label endogenous proteins.

J Neurosci 2014 Dec;34(50):16698-712

Vollum Institute, Oregon Health and Science University, Portland, Oregon 97239, Howard Hughes Medical Institute, Janelia Farms Research Campus, Ashburn, Virginia 20147,

Stoichiometric labeling of endogenous synaptic proteins for high-contrast live-cell imaging in brain tissue remains challenging. Here, we describe a conditional mouse genetic strategy termed endogenous labeling via exon duplication (ENABLED), which can be used to fluorescently label endogenous proteins with near ideal properties in all neurons, a sparse subset of neurons, or specific neuronal subtypes. We used this method to label the postsynaptic density protein PSD-95 with mVenus without overexpression side effects. We demonstrated that mVenus-tagged PSD-95 is functionally equivalent to wild-type PSD-95 and that PSD-95 is present in nearly all dendritic spines in CA1 neurons. Within spines, while PSD-95 exhibited low mobility under basal conditions, its levels could be regulated by chronic changes in neuronal activity. Notably, labeled PSD-95 also allowed us to visualize and unambiguously examine otherwise-unidentifiable excitatory shaft synapses in aspiny neurons, such as parvalbumin-positive interneurons and dopaminergic neurons. Our results demonstrate that the ENABLED strategy provides a valuable new approach to study the dynamics of endogenous synaptic proteins in vivo.
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http://dx.doi.org/10.1523/JNEUROSCI.3888-14.2014DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4261096PMC
December 2014

Mechanism of androgen receptor corepression by CKβBP2/CRIF1, a multifunctional transcription factor coregulator expressed in prostate cancer.

Mol Cell Endocrinol 2014 Jan 5;382(1):302-313. Epub 2013 Oct 5.

Laboratories for Reproductive Biology, Department of Pediatrics, University of North Carolina, School of Medicine, Chapel Hill, NC, United States; Lineberger Comprehensive Cancer Center, University of North Carolina, School of Medicine, Chapel Hill, NC, United States. Electronic address:

The transcription factor coregulator Casein kinase IIβ-binding protein 2 or CR6-interacting factor 1 (CKβBP2/CRIF1) binds the androgen receptor (AR) in prostate cancer cells and in response to dihydrotestosterone localizes with AR on the prostate-specific antigen gene enhancer, but does not bind DNA suggesting CKβBP2/CRIF1 localization in chromatin is determined by AR. In this study we show also that CKβBP2/CRIF1 inhibits wild-type AR and AR N-terminal transcriptional activity, binds to the AR C-terminal region, inhibits interaction of the AR N- and C-terminal domains (N/C interaction) and competes with p160 coactivator binding to the AR C-terminal domain, suggesting CKβBP2/CRIF1 interferes with AR activation functions 1 and 2. CKβBP2/CRIF1 is expressed mainly in stromal cells of benign prostatic hyperplasia and in stroma and epithelium of prostate cancer. CKβBP2/CRIF1 protein is increased in epithelium of androgen-dependent prostate cancer compared to benign prostatic hyperplasia and decreased slightly in castration recurrent epithelium compared to androgen-dependent prostate cancer. The multifunctional CKβBP2/CRIF1 is a STAT3 interacting protein and reported to be a coactivator of STAT3. CKβBP2/CRIF1 is expressed with STAT3 in prostate cancer where STAT3 may help to offset the AR repressor effect of CKβBP2/CRIF1 and allow AR regulation of prostate cancer growth.
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http://dx.doi.org/10.1016/j.mce.2013.09.036DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3880566PMC
January 2014

Convergence of pontine and proprioceptive streams onto multimodal cerebellar granule cells.

Elife 2013 Feb 26;2:e00400. Epub 2013 Feb 26.

Janelia Farm Research Campus, Howard Hughes Medical Institute , Ashburn , United States.

Cerebellar granule cells constitute the majority of neurons in the brain and are the primary conveyors of sensory and motor-related mossy fiber information to Purkinje cells. The functional capability of the cerebellum hinges on whether individual granule cells receive mossy fiber inputs from multiple precerebellar nuclei or are instead unimodal; this distinction is unresolved. Using cell-type-specific projection mapping with synaptic resolution, we observed the convergence of separate sensory (upper body proprioceptive) and basilar pontine pathways onto individual granule cells and mapped this convergence across cerebellar cortex. These findings inform the long-standing debate about the multimodality of mammalian granule cells and substantiate their associative capacity predicted in the Marr-Albus theory of cerebellar function. We also provide evidence that the convergent basilar pontine pathways carry corollary discharges from upper body motor cortical areas. Such merging of related corollary and sensory streams is a critical component of circuit models of predictive motor control. DOI:http://dx.doi.org/10.7554/eLife.00400.001.
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http://dx.doi.org/10.7554/eLife.00400DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3582988PMC
February 2013

Activation of the androgen receptor by intratumoral bioconversion of androstanediol to dihydrotestosterone in prostate cancer.

Cancer Res 2011 Feb 8;71(4):1486-96. Epub 2011 Feb 8.

Department of Urology, Roswell Park Cancer Institute, Buffalo, New York, USA.

The androgen receptor (AR) mediates the growth of benign and malignant prostate in response to dihydrotestosterone (DHT). In patients undergoing androgen deprivation therapy for prostate cancer, AR drives prostate cancer growth despite low circulating levels of testicular androgen and normal levels of adrenal androgen. In this report, we demonstrate the extent of AR transactivation in the presence of 5α-androstane-3α,17β-diol (androstanediol) in prostate-derived cell lines parallels the bioconversion of androstanediol to DHT. AR transactivation in the presence of androstanediol in prostate cancer cell lines correlated mainly with mRNA and protein levels of 17β-hydroxysteroid dehydrogenase 6 (17β-HSD6), one of several enzymes required for the interconversion of androstanediol to DHT and the inactive metabolite androsterone. Levels of retinol dehydrogenase 5, and dehydrogenase/reductase short-chain dehydrogenase/reductase family member 9, which also convert androstanediol to DHT, were lower than 17β-HSD6 in prostate-derived cell lines and higher in the castration-recurrent human prostate cancer xenograft. Measurements of tissue androstanediol using mass spectrometry demonstrated androstanediol metabolism to DHT and androsterone. Administration of androstanediol dipropionate to castration-recurrent CWR22R tumor-bearing athymic castrated male mice produced a 28-fold increase in intratumoral DHT levels. AR transactivation in prostate cancer cells in the presence of androstanediol resulted from the cell-specific conversion of androstanediol to DHT, and androstanediol increased LAPC-4 cell growth. The ability to convert androstanediol to DHT provides a mechanism for optimal utilization of androgen precursors and catabolites for DHT synthesis.
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http://dx.doi.org/10.1158/0008-5472.CAN-10-1343DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3075600PMC
February 2011

Transcriptional synergy between melanoma antigen gene protein-A11 (MAGE-11) and p300 in androgen receptor signaling.

J Biol Chem 2010 Jul 6;285(28):21824-36. Epub 2010 May 6.

Department of Pediatrics, University of North Carolina, Chapel Hill, North Carolina 27599, USA.

Androgen receptor (AR)-mediated gene regulation involves interactions with coregulatory proteins that include the melanoma antigen gene protein-A11 (MAGE-11). To understand the functional significance of sequence similarity between MAGE-11 and the adenovirus early protein E1A, we determined whether MAGE-11 contributes to AR transcriptional activity through an interaction with p300, a potent and ubiquitous transcriptional regulator. Here, we report that MAGE-11 interacts with the NH(2)-terminal region of p300 through the MAGE-11 MXXIF motif (185)MXXIF(189), with transcriptional activity depending on the MAGE-11 F-box and MAPK phosphorylation. The MAGE-11- and p300-dependent increase in AR transactivation required the NH(2)-terminal regions of AR and p300, p300 acetyltransferase activity, and the AR FXXLF motif (23)FQNLF(27) interaction with MAGE-11. MAGE-11 linked AR to p300 and the p160 coactivator, transcriptional intermediary protein 2 (TIF2). The p300 NH(2)-terminal FXXLF motif (33)FGSLF(37) was required for transcriptional activation by TIF2. Increased expression of p300 decreased the ubiquitinylation of MAGE-11 and transiently increased endogenous MAGE-11 levels. Autoacetylation of p300 and decreased acetylation of TIF2 were evident in the MAGE-11, p300, and TIF2 complex. The studies suggest that MAGE-11 links NH(2)-terminal domains of AR and p300 to promote transcriptional synergy through a cadre of FXXLF-related interacting motifs.
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http://dx.doi.org/10.1074/jbc.M110.120600DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2898404PMC
July 2010

Melanoma antigen gene protein-A11 (MAGE-11) F-box links the androgen receptor NH2-terminal transactivation domain to p160 coactivators.

J Biol Chem 2009 Dec 14;284(50):34793-808. Epub 2009 Oct 14.

Curriculum in Toxicology, University of North Carolina, Chapel Hill, North Carolina 27599-7500, USA.

Androgen-dependent transcriptional activity by the androgen receptor (AR) and its coregulators is required for male reproductive development and function. In humans and other primates, melanoma antigen gene protein-A11 (MAGE-11) is an AR selective coregulator that increases AR transcriptional activity. Here we show that the interaction between AR and MAGE-11 is mediated by AR NH(2)-terminal FXXLF motif binding to a highly conserved MAGE-11 F-box in the MAGE homology domain, and is modulated by serum stimulation of mitogen-activated protein kinase phosphorylation of MAGE-11 Ser-174. The MAGE-11-dependent increase in AR transcriptional activity is mediated by a direct interaction between MAGE-11 and transcriptional intermediary factor 2 (TIF2) through the NH(2)-terminal region of TIF2, and by a MAGE-11 FXXIF motif interaction with an F-box-like region in activation domain 1 of TIF2. The results suggest that MAGE-11 functions as a bridging factor to recruit AR coactivators through a novel FXX(L/I)F motif-F-box interaction paradigm.
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http://dx.doi.org/10.1074/jbc.M109.065979DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2787342PMC
December 2009

Increased expression of androgen receptor coregulator MAGE-11 in prostate cancer by DNA hypomethylation and cyclic AMP.

Mol Cancer Res 2009 Apr;7(4):523-35

University of North Carolina, Chapel Hill, NC 27599-7500, USA.

Melanoma antigen gene protein-A11 (MAGE-11) of the MAGE family of cancer germ-line antigens increases androgen receptor (AR) transcriptional activity through its interaction with the AR NH(2)-terminal FXXLF motif. The present study investigated the regulatory mechanisms that control MAGE-11 expression during androgen deprivation therapy and prostate cancer progression. Studies include the CWR22 xenograft model of human prostate cancer, clinical specimens of benign and malignant prostate, and prostate cancer cell lines. MAGE-11 mRNA levels increased 100- to 1,500-fold during androgen deprivation therapy and prostate cancer progression, with highest levels in the castration-recurrent CWR22 xenograft and clinical specimens of castration-recurrent prostate cancer. Pyrosequencing of genomic DNA from prostate cancer specimens and cell lines indicated the increase in MAGE-11 resulted from DNA hypomethylation of a CpG island in the 5' promoter of the MAGE-11 gene. Sodium bisulfite sequencing of genomic DNA from benign and malignant prostate tumors and prostate cancer cell lines revealed DNA hypomethylation at individual CpG sites at the transcription start site were most critical for MAGE-11 expression. Cyclic AMP (cAMP) also increased MAGE-11 expression and AR transcriptional activity in prostate cancer cell lines. However, cAMP did not alter DNA methylation of the promoter and its effects were inhibited by extensive DNA methylation in the MAGE-11 promoter region. Increased expression of the AR coregulator MAGE-11 through promoter DNA hypomethylation and cAMP provides a novel mechanism for increased AR signaling in castration-recurrent prostate cancer.
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http://dx.doi.org/10.1158/1541-7786.MCR-08-0400DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2670465PMC
April 2009

Epidermal-growth-factor-dependent phosphorylation and ubiquitinylation of MAGE-11 regulates its interaction with the androgen receptor.

Mol Cell Biol 2008 Mar 22;28(6):1947-63. Epub 2008 Jan 22.

Laboratories for Reproductive Biology, CB 7500, University of North Carolina, Chapel Hill, NC 27599-7500, USA.

The androgen receptor (AR) is a ligand-activated transcription factor that interacts with coregulatory proteins during androgen-dependent gene regulation. Melanoma antigen gene protein 11 (MAGE-11) is an AR coregulator that specifically binds the AR NH(2)-terminal FXXLF motif and modulates the AR NH(2)- and carboxyl-terminal N/C interaction to increase AR transcriptional activity. Here we demonstrate that epidermal growth factor (EGF) signaling increases androgen-dependent AR transcriptional activity through the posttranslational modification of MAGE-11. EGF in the presence of dihydrotestosterone stabilizes the AR-MAGE complex through the site-specific phosphorylation of MAGE-11 at Thr-360 and ubiquitinylation at Lys-240 and Lys-245. The time-dependent EGF-induced increase in AR transcriptional activity by MAGE-11 is mediated through AR activation functions 1 and 2 in association with the increased turnover of AR and MAGE-11. The results reveal a dynamic mechanism whereby growth factor signaling increases AR transcriptional activity through the covalent modification of an AR-specific coregulatory protein. Sequence conservation of the MAGE-11 phosphorylation and ubiquitinylation sites throughout the MAGE gene family suggests common regulatory mechanisms for this group of cancer-testis antigens.
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http://dx.doi.org/10.1128/MCB.01672-07DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2268407PMC
March 2008

Hormone control and expression of androgen receptor coregulator MAGE-11 in human endometrium during the window of receptivity to embryo implantation.

Mol Hum Reprod 2008 Feb 29;14(2):107-16. Epub 2007 Nov 29.

Laboratories for Reproductive Biology, University of North Carolina, Chapel Hill, NC 27599, USA.

The androgen receptor (AR) is a ligand-activated transcription factor of the male and female reproductive tracts whose activity is modulated by coregulator binding. We recently identified melanoma antigen gene protein-11 (MAGE-11) of the MAGEA gene family that functions as an AR coregulator by binding the AR N-terminal FXXLF motif. Here we report that MAGE-11 is expressed in a temporal fashion in endometrium of normally cycling women. Highest levels of MAGE-11 mRNA and protein occur in the mid-secretory stage, coincident with the window of uterine receptivity to embryo implantation. Studies in human endometrial cell lines together with the hormone profile of the menstrual cycle and pattern of estrogen receptor-alpha expression in cycling endometrium suggest the rise in MAGE-11 mRNA results from down-regulation by estradiol during the proliferative phase and up-regulation by cyclic AMP signaling in the early and mid-secretory stage. In agreement with its coregulatory function, MAGE-11 localizes with AR in glandular epithelial cell nuclei in the mid-secretory stage. The increase in AR protein in the mid-secretory endometrium without an increase in AR mRNA suggests MAGE-11 stabilizes AR in glandular epithelial cell nuclei. This was supported by expression studies at low androgen levels indicating AR stabilization by MAGE-11 dependent on the AR N-terminal transactivation domain. The results suggest that MAGE-11 functions as a coregulator that increases AR transcriptional activity during the establishment of uterine receptivity in the human female.
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http://dx.doi.org/10.1093/molehr/gam080DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2701302PMC
February 2008

Melanoma antigen gene protein MAGE-11 regulates androgen receptor function by modulating the interdomain interaction.

Mol Cell Biol 2005 Feb;25(4):1238-57

Laboratories for Reproductive Biology, CB# 7500, Rm. 3340, Medical Biomolecular Research Building, University of North Carolina, Chapel Hill, NC 27599, USA.

Gene activation by steroid hormone receptors involves the recruitment of the steroid receptor coactivator (SRC)/p160 coactivator LXXLL motifs to activation function 2 (AF2) in the ligand binding domain. For the androgen receptor (AR), AF2 also serves as the interaction site for the AR NH(2)-terminal FXXLF motif in the androgen-dependent NH(2)-terminal and carboxyl-terminal (N/C) interaction. The relative importance of the AR AF2 site has been unclear, since the AR FXXLF motif interferes with coactivator recruitment by competitive inhibition of LXXLL motif binding. In this report, we identified the X chromosome-linked melanoma antigen gene product MAGE-11 as an AR coregulator that specifically binds the AR NH(2)-terminal FXXLF motif. Binding of MAGE-11 to the AR FXXLF alpha-helical region stabilizes the ligand-free AR and, in the presence of an agonist, increases exposure of AF2 to the recruitment and activation by the SRC/p160 coactivators. Intracellular association between AR and MAGE-11 is supported by their coimmunoprecipitation and colocalization in the absence and presence of hormone and by competitive inhibition of the N/C interaction. AR transactivation increases in response to MAGE-11 and the SRC/p160 coactivators through mechanisms that include but are not limited to the AF2 site. MAGE-11 is expressed in androgen-dependent tissues and in prostate cancer cell lines. The results suggest MAGE-11 is a unique AR coregulator that increases AR activity by modulating the AR interdomain interaction.
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http://dx.doi.org/10.1128/MCB.25.4.1238-1257.2005DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC548016PMC
February 2005

An androgen receptor NH2-terminal conserved motif interacts with the COOH terminus of the Hsp70-interacting protein (CHIP).

J Biol Chem 2004 Jul 23;279(29):30643-53. Epub 2004 Apr 23.

Laboratories for Reproductive Biology, University of North Carolina, Chapel Hill, North Carolina 27599, USA.

The NH2-terminal sequence of steroid receptors is highly variable between different receptors and in the same receptor from different species. In this study, a primary sequence homology comparison identified a 14-amino acid NH2-terminal motif of the human androgen receptor (AR) that is common to AR from all species reported, including the lower vertebrates. The evolutionarily conserved motif is unique to AR, with the exception of a partial sequence in the glucocorticoid receptor of higher species. The presence of the conserved motif in AR and the glucocorticoid receptor and its absence in other steroid receptors suggests convergent evolution. The function of the AR NH2-terminal conserved motif was suggested from a yeast two-hybrid screen that identified the COOH terminus of the Hsp70-interacting protein (CHIP) as a binding partner. We found that CHIP functions as a negative regulator of AR transcriptional activity by promoting AR degradation. In support of this, two mutations in the AR NH2-terminal conserved motif previously identified in the transgenic adenocarcinoma of mouse prostate model reduced the interaction between CHIP and AR. Our results suggest that the AR NH2-terminal domain contains an evolutionarily conserved motif that functions to limit AR transcriptional activity. Moreover, we demonstrate that the combination of comparative sequence alignment and yeast two-hybrid screening using short conserved peptides as bait provides an effective strategy to probe the structure-function relationships of steroid receptor NH2-terminal domains and other intrinsically unstructured transcriptional regulatory proteins.
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http://dx.doi.org/10.1074/jbc.M403117200DOI Listing
July 2004