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Yun Q, Ma SF, Zhang WN, Gu M, Wang J. FoxG1 as a Potential Therapeutic Target for Alzheimer's Disease: Modulating NLRP3 Inflammasome via AMPK/mTOR Autophagy Pathway. Cell Mol Neurobiol 2024; 44:35. [PMID: 38630150 PMCID: PMC11023968 DOI: 10.1007/s10571-024-01467-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2023] [Accepted: 02/27/2024] [Indexed: 04/19/2024]
Abstract
An increasing body of research suggests that promoting microglial autophagy hinders the neuroinflammation initiated though the NLRP3 inflammasome activation in Alzheimer's disease (AD). The function of FoxG1, a crucial transcription factor involved in cell survival by regulating mitochondrial function, remains unknown during the AD process and neuroinflammation occurs. In the present study, we firstly found that Aβ peptides induced AD-like neuroinflammation upregulation and downregulated the level of autophagy. Following low-dose Aβ25-35 stimulation, FoxG1 expression and autophagy exhibited a gradual increase. Nevertheless, with high-concentration Aβ25-35 treatment, progressive decrease in FoxG1 expression and autophagy levels as the concentration of Aβ25-35 escalated. In addition, FoxG1 has a positive effect on cell viability and autophagy in the nervous system. In parallel with the Aβ25-35 stimulation, we employed siRNA to decrease the expression of FoxG1 in N2A cells. A substantial reduction in autophagy level (Beclin1, LC3II, SQSTM1/P62) and a notable growth in inflammatory response (NLRP3, TNF-α, and IL-6) were observed. In addition, we found FoxG1 overexpression owned the effect on the activation of AMPK/mTOR autophagy pathway and siRNA-FoxG1 successfully abolished this effect. Lastly, FoxG1 suppressed the NLRP3 inflammasome and enhanced the cognitive function in AD-like mouse model induced by Aβ25-35. Confirmed by cellular and animal experiments, FoxG1 suppressed NLRP3-mediated neuroinflammation, which was strongly linked to autophagy regulated by AMPK/mTOR. Taken together, FoxG1 may be a critical node in the pathologic progression of AD and has the potential to serve as therapeutic target.
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Affiliation(s)
- Qi Yun
- Changzhou Children's Hospital Affiliated to Nantong University, 958 Zhongwu Avenue, Changzhou, 213000, Jiangsu Province, China
| | - Si-Fei Ma
- Changzhou Blood Center, 118 Canal Road, Changzhou, 213000, Jiangsu Province, China
| | - Wei-Ning Zhang
- Department of Laboratory Medicine, School of Medicine, Jiangsu University, 301 Xuefu Road, Zhenjiang, 213000, Jiangsu Province, China
| | - Meng Gu
- Changzhou Children's Hospital Affiliated to Nantong University, 958 Zhongwu Avenue, Changzhou, 213000, Jiangsu Province, China.
| | - Jia Wang
- Department of Laboratory Medicine, School of Medicine, Jiangsu University, 301 Xuefu Road, Zhenjiang, 213000, Jiangsu Province, China.
- The Fourth Affiliated Hospital of Jiangsu University, Zhenjiang, 212001, Jiangsu Province, PR China.
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Yan X, Hou L, Zhang C. FOXG1 is involved in mouse ovarian functions and embryogenesis. J Steroid Biochem Mol Biol 2023; 233:106372. [PMID: 37536505 DOI: 10.1016/j.jsbmb.2023.106372] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/12/2023] [Revised: 07/26/2023] [Accepted: 07/27/2023] [Indexed: 08/05/2023]
Abstract
TGF-β superfamily has long been demonstrated to be essential for folliculogenesis and luteinization. Forkhead box G1 (FOXG1, also known as BF1), a member of the FOX family and an inhibitor of TGF-β signaling pathway, is a nucleocytoplasmic transcription factor that is essential for forebrain development. FOXG1 is involved in neurodevelopment and cancer pathology, however, little is known about the role of FOXG1 in reproduction. In this study, the spatiotemporal expression pattern of FOXG1 was examined during early mouse oocyte and embryonic development and its role during corpora luteum (CL) formation was further elucidated. The results showed that FOXG1 is localized in oocytes, theca cells (TCs) and CLs. After fertilization, FOXG1 is expressed at all stages during early embryogenesis, from zygotes to blastocysts. Following gonadotropin administration in immature mice, the expression of Foxg1 significantly increased along with steroidogenic genes, including Star, Hsd3β, Cyp11a1, as well as Cyp17a1 and Cyp19a1. The latter two first increased after pregnant mare serum gonadotropin stimulation, then decreased in response to hCG treatment. In addition, silencing of Foxg1 significantly reduced the concentration of testosterone and estrogen in cultured primary granulosa cells (GCs) and TCs (P < 0.05). Mechanistic studies demonstrated that the expression level of genes that are critical in estrogen synthesis were significantly reduced after Foxg1 silencing, including Cyp17a1 and Cyp19a1. In conclusion, FOXG1 is expressed in a stage-specific manner during folliculogenesis and embryogenesis and exerts a regulatory influence on testosterone and estrogen synthesis.
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Affiliation(s)
- Xingyu Yan
- Center for Reproductive Medicine, Ren Ji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai 200135, China; Shanghai Key Laboratory for Assisted Reproduction and Reproductive Genetics, Shanghai, China; Shandong Provincial Key Laboratory of Animal Resistance Biology, College of Life Sciences, Shandong Normal University, Jinan, Shandong 250014, China; Fujian Provincial Key Laboratory of Reproductive Health Research, Medical College of Xiamen University, Xiamen, Fujian 361102, China
| | - Linlin Hou
- Shandong Provincial Key Laboratory of Animal Resistance Biology, College of Life Sciences, Shandong Normal University, Jinan, Shandong 250014, China
| | - Cong Zhang
- Center for Reproductive Medicine, Ren Ji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai 200135, China; Shanghai Key Laboratory for Assisted Reproduction and Reproductive Genetics, Shanghai, China; Shandong Provincial Key Laboratory of Animal Resistance Biology, College of Life Sciences, Shandong Normal University, Jinan, Shandong 250014, China.
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3
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Lottini G, Baggiani M, Chesi G, D'Orsi B, Quaranta P, Lai M, Pancrazi L, Onorati M, Pistello M, Freer G, Costa M. Zika virus induces FOXG1 nuclear displacement and downregulation in human neural progenitors. Stem Cell Reports 2022; 17:1683-1698. [PMID: 35714598 PMCID: PMC9287670 DOI: 10.1016/j.stemcr.2022.05.008] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2021] [Revised: 05/13/2022] [Accepted: 05/17/2022] [Indexed: 11/25/2022] Open
Abstract
Congenital alterations in the levels of the transcription factor Forkhead box g1 (FOXG1) coding gene trigger "FOXG1 syndrome," a spectrum that recapitulates birth defects found in the "congenital Zika syndrome," such as microcephaly and other neurodevelopmental conditions. Here, we report that Zika virus (ZIKV) infection alters FOXG1 nuclear localization and causes its downregulation, thus impairing expression of genes involved in cell replication and apoptosis in several cell models, including human neural progenitor cells. Growth factors, such as EGF and FGF2, and Thr271 residue located in FOXG1 AKT domain, take part in the nuclear displacement and apoptosis protection, respectively. Finally, by progressive deletion of FOXG1 sequence, we identify the C-terminus and the residues 428-481 as critical domains. Collectively, our data suggest a causal mechanism by which ZIKV affects FOXG1, its target genes, cell cycle progression, and survival of human neural progenitors, thus contributing to microcephaly.
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Affiliation(s)
- Giulia Lottini
- Centro Retrovirus, Department of Translational Research, University of Pisa, Pisa 56127, Italy; Department of Medical Biotechnologies, University of Siena, Siena 53100, Italy
| | - Matteo Baggiani
- Unit of Cell and Developmental Biology, Department of Biology, University of Pisa, Pisa 56127, Italy
| | - Giulia Chesi
- Centro Retrovirus, Department of Translational Research, University of Pisa, Pisa 56127, Italy
| | - Beatrice D'Orsi
- Institute of Neuroscience, Italian National Research Council (CNR), Via Moruzzi, 1, Pisa 56124, Italy; Centro Pisano ricerca e implementazione clinica Flash Radiotherapy (CPFR@CISUP), Presidio S. Chiara, ed.18 via Roma, 67, Pisa 56126, Italy
| | - Paola Quaranta
- Centro Retrovirus, Department of Translational Research, University of Pisa, Pisa 56127, Italy
| | - Michele Lai
- Centro Retrovirus, Department of Translational Research, University of Pisa, Pisa 56127, Italy
| | - Laura Pancrazi
- Institute of Neuroscience, Italian National Research Council (CNR), Via Moruzzi, 1, Pisa 56124, Italy
| | - Marco Onorati
- Unit of Cell and Developmental Biology, Department of Biology, University of Pisa, Pisa 56127, Italy
| | - Mauro Pistello
- Centro Retrovirus, Department of Translational Research, University of Pisa, Pisa 56127, Italy
| | - Giulia Freer
- Centro Retrovirus, Department of Translational Research, University of Pisa, Pisa 56127, Italy
| | - Mario Costa
- Institute of Neuroscience, Italian National Research Council (CNR), Via Moruzzi, 1, Pisa 56124, Italy; Centro Pisano ricerca e implementazione clinica Flash Radiotherapy (CPFR@CISUP), Presidio S. Chiara, ed.18 via Roma, 67, Pisa 56126, Italy; Laboratory of Biology "Bio@SNS", Scuola Normale Superiore, Piazza dei Cavalieri, Pisa 56124, Italy.
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Dahiya UR, Heemers HV. Analyzing the Androgen Receptor Interactome in Prostate Cancer: Implications for Therapeutic Intervention. Cells 2022; 11:936. [PMID: 35326387 PMCID: PMC8946651 DOI: 10.3390/cells11060936] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2022] [Revised: 03/02/2022] [Accepted: 03/04/2022] [Indexed: 12/29/2022] Open
Abstract
The androgen receptor (AR) is a member of the ligand-activated nuclear receptor family of transcription factors. AR's transactivation activity is turned on by the binding of androgens, the male sex steroid hormones. AR is critical for the development and maintenance of the male phenotype but has been recognized to also play an important role in human diseases. Most notably, AR is a major driver of prostate cancer (CaP) progression, which remains the second leading cause of cancer deaths in American men. Androgen deprivation therapies (ADTs) that interfere with interactions between AR and its activating androgen ligands have been the mainstay for treatment of metastatic CaP. Although ADTs are effective and induce remissions, eventually they fail, while the growth of the majority of ADT-resistant CaPs remains under AR's control. Alternative approaches to inhibit AR activity and bypass resistance to ADT are being sought, such as preventing the interaction between AR and its cofactors and coregulators that is needed to execute AR-dependent transcription. For such strategies to be efficient, the 3D conformation of AR complexes needs to be well-understood and AR-regulator interaction sites resolved. Here, we review current insights into these 3D structures and the protein interaction sites in AR transcriptional complexes. We focus on methods and technological approaches used to identify AR interactors and discuss challenges and limitations that need to be overcome for efficient therapeutic AR complex disruption.
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Affiliation(s)
| | - Hannelore V. Heemers
- Department of Cancer Biology, Lerner Research Institute, Cleveland Clinic, NB-40, 9500 Euclid Avenue, Cleveland, OH 44195, USA;
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Zeng F, Xue M, Xiao T, Li Y, Xiao S, Jiang B, Ren C. MiR-200b promotes the cell proliferation and metastasis of cervical cancer by inhibiting FOXG1. Biomed Pharmacother 2016; 79:294-301. [PMID: 27044840 DOI: 10.1016/j.biopha.2016.02.033] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2015] [Revised: 02/16/2016] [Accepted: 02/16/2016] [Indexed: 12/31/2022] Open
Abstract
BACKGROUND Previous studies have revealed the important role of miR-200b in cancer biology, including its upregulation in cervical cancer. However, miR-200b function in cervical cancer progression remains unclear. Thus, this study aims to explore the functional role of miR-200b in cervical cancer development, involving its potential regulation on FoxG1, one transcriptional repressor. METHODS Thirty paired cervical cancer samples were used to analyze the expression of miR-200b and FoxG1 by real time PCR and western blot analysis. Further gain- and loss-of-function studies were performed to validate FoxG1 as one miR-200b target, in line with luciferase report assays. MiR-200b silence was also conducted to observe its regulation on cell viability, migration and invasion in vitro, while tumor growth in vivo was tracked through the delivery of miR-200b inhibitor. RESULTS MiR-200b upregulation was confirmed in cancer tissues or cells as compared to normal controls, while FoxG1 downregulation was observed and then FoxG1 was definitely validated as one miR-200b target. Further in vitro studies showed that enforced miR-200b downregulation induced the decrease of cell ability, with increased cell apoptosis, and attenuated ability of cell migration and invasion in both HeLa and C33A cells, while further inhibition of FoxG1 expression could reverse all these changes. In addition, miR-200b silence in vivo strongly inhibited tumor growth. CONCLUSION Upregulated miR-200b in cervical cancer was proven to show positive regulation on cervical cancer development by directly targeting FoxG1. Moreover, miR-200b silence was proposed to inhibit tumor growth in vivo, implying its therapeutic value in cervical cancer treatment.
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Affiliation(s)
- Fei Zeng
- Department of Gynecology, the Third Xiangya Hospital of Central South University, Changsha, Hunan Province, China
| | - Min Xue
- Department of Gynecology, the Third Xiangya Hospital of Central South University, Changsha, Hunan Province, China.
| | - Ting Xiao
- Third Xiangya Hospital of Central South University, Changsha, Hunan Province, China
| | - Yueran Li
- Department of Gynecology, the Third Xiangya Hospital of Central South University, Changsha, Hunan Province, China
| | - Songshu Xiao
- Department of Gynecology, the Third Xiangya Hospital of Central South University, Changsha, Hunan Province, China
| | - Bin Jiang
- Department of Gynecology, the Third Xiangya Hospital of Central South University, Changsha, Hunan Province, China
| | - Caiping Ren
- Cancer Research Institute, Collaborative Innovation Center for Cancer Medicine, Key Laboratory for Carcinogenesis of Chinese Ministry of Health, School of Basic Medical Science, Central South University, Xiangya Road 110, Changsha 410078, Hunan Province, China.
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Li JV, Chien CD, Garee JP, Xu J, Wellstein A, Riegel AT. Transcriptional repression of AIB1 by FoxG1 leads to apoptosis in breast cancer cells. Mol Endocrinol 2013; 27:1113-27. [PMID: 23660594 DOI: 10.1210/me.2012-1353] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
The oncogene nuclear receptor coactivator amplified in breast cancer 1 (AIB1) is a transcriptional coactivator that is overexpressed in various types of human cancers. However, the molecular mechanisms controlling AIB1 expression in the majority of cancers remain unclear. In this study, we identified a novel interacting protein of AIB1, forkhead-box protein G1 (FoxG1), which is an evolutionarily conserved forkhead-box transcriptional corepressor. We show that FoxG1 expression is low in breast cancer cell lines and that low levels of FoxG1 are correlated with a worse prognosis in breast cancer. We also demonstrate that transient overexpression of FoxG1 can suppress endogenous levels of AIB1 mRNA and protein in MCF-7 breast cancer cells. Exogenously expressed FoxG1 in MCF-7 cells also leads to apoptosis that can be rescued in part by AIB1 overexpression. Using chromatin immunoprecipitation, we determined that FoxG1 is recruited to a region of the AIB1 gene promoter previously characterized to be responsible for AIB1-induced, positive autoregulation of transcription through the recruitment of an activating, multiprotein complex, involving AIB1, E2F transcription factor 1, and specificity protein 1. Increased FoxG1 expression significantly reduces the recruitment of AIB1, E2F transcription factor 1 and E1A-binding protein p300 to this region of the endogenous AIB1 gene promoter. Our data imply that FoxG1 can function as a pro-apoptotic factor in part through suppression of AIB1 coactivator transcription complex formation, thereby reducing the expression of the AIB1 oncogene.
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Affiliation(s)
- Jordan V Li
- Department of Pharmacology, Lombardi Cancer Center, Georgetown University, Research Building E307, 3970 Reservoir Road Northwest, Washington, DC 20007-2197, USA
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Danesin C, Houart C. A Fox stops the Wnt: implications for forebrain development and diseases. Curr Opin Genet Dev 2012; 22:323-30. [DOI: 10.1016/j.gde.2012.05.001] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2012] [Revised: 04/17/2012] [Accepted: 05/15/2012] [Indexed: 10/28/2022]
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Gene expression profile in bone of diabetes-prone BB/OK rats fed a high-fat diet. GENES AND NUTRITION 2012; 8:99-104. [PMID: 22639302 DOI: 10.1007/s12263-012-0299-1] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/27/2012] [Accepted: 05/02/2012] [Indexed: 12/13/2022]
Abstract
A high-fat diet (HFD) has been recognized as a risk factor for diseases such as dyslipidemia, atherosclerosis, obesity, and osteoporosis. However, studies analyzing gene expression after HFD in bone are rare. That prompted us to analyze the expression of selected genes in bone of 4-week-old diabetes-prone B(io)B(reeding) rats. Two breeding pairs were fed a HFD (+10 % tallow) or were fed a normal diet (ND; Ssniff R-Z) before mating and afterward during pregnancy. After the birth of progeny, parents continued to be given HFD or ND until the progeny was weaned (3 weeks). Thereafter, offspring were weaned and were fed the same food as their parents up to an age of 4 weeks. Body weight was measured at an age of 4 weeks, and subsequently 13 HFD rats and 13 ND rats were killed and the tibial bone was harvested to analyze the expression of 53 genes in bone. All rats fed HFD were significantly heavier than rats fed ND after 3 and 4 weeks. The diet also influenced the expression of genes in bone. There were significant differences in 20 out of 53 genes studied between rats fed HFD compared with rats fed ND. Four out of 20 had a lower and 17 out of 20 genes a higher expression in HFD rats, but differences in gene expression showed obvious differences between males and females. There were only two genes that were similarly different between males and females: Bmp4 and Atf4. Two genes, Foxg1 and Npy, were inversely expressed in males and females. It seems that the gene expression is differently regulated by diet during pregnancy and later in life between males and females. Nevertheless, it cannot be excluded that HFD also acts as an epigenetic factor in the development of offspring in utero.
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Dastidar SG, Narayanan S, Stifani S, D'Mello SR. Transducin-like enhancer of Split-1 (TLE1) combines with Forkhead box protein G1 (FoxG1) to promote neuronal survival. J Biol Chem 2012; 287:14749-59. [PMID: 22354967 DOI: 10.1074/jbc.m111.328336] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Transducin-like enhancer of split-1 (TLE1) plays a critical role in the regulation of neurogenesis by inhibiting the differentiation of neural progenitor cells into neurons. Although TLE1 is also expressed highly in the postnatal brain and through adulthood, its role in postmitotic neurons is not clear. Using cultures of cerebellar granule neurons, we show that expression of TLE1 is reduced in neurons primed to die. Reestablishment of elevated TLE1 levels by ectopic expression protects neurons from death, whereas suppression of TLE1 expression in otherwise healthy neurons induces cell death. These results show that TLE1 is necessary for the maintenance of neuronal survival. Experiments using pharmacological inhibitors as well as expression of point mutants indicate that phosphorylation of TLE1 by casein kinase-2 (CK2) at Ser-239 and Ser-253 is necessary for its survival-promoting activity. TLE1-mediated survival is also inhibited by pharmacological inhibition of PI3K-Akt signaling but not by inhibitors of Raf-MEK-ERK signaling or other molecules, including histone deacetylases, calcium calmodulin kinase, or CK1. The survival-promoting activity of TLE1 depends critically on interaction with FoxG1, another protein involved in the regulation of neurogenesis and shown previously to promote survival of postmitotic neurons. Likewise, the ability of FoxG1 to promote neuronal survival depends on TLE1. Taken together, our study demonstrates that TLE1 cooperates with FoxG1 to promote neuronal survival in a CK2- and PI3K-Akt-dependent manner.
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Bagchi G, Zhang Y, Stanley KA, Waxman DJ. Complex modulation of androgen responsive gene expression by methoxyacetic acid. Reprod Biol Endocrinol 2011; 9:42. [PMID: 21453523 PMCID: PMC3083340 DOI: 10.1186/1477-7827-9-42] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/10/2011] [Accepted: 03/31/2011] [Indexed: 01/12/2023] Open
Abstract
BACKGROUND Optimal androgen signaling is critical for testicular development and spermatogenesis. Methoxyacetic acid (MAA), the primary active metabolite of the industrial chemical ethylene glycol monomethyl ether, disrupts spermatogenesis and causes testicular atrophy. Transcriptional trans-activation studies have indicated that MAA can enhance androgen receptor activity, however, whether MAA actually impacts the expression of androgen-responsive genes in vivo, and which genes might be affected is not known. METHODS A mouse TM3 Leydig cell line that stably expresses androgen receptor (TM3-AR) was prepared and analyzed by transcriptional profiling to identify target gene interactions between MAA and testosterone on a global scale. RESULTS MAA is shown to have widespread effects on androgen-responsive genes, affecting processes ranging from apoptosis to ion transport, cell adhesion, phosphorylation and transcription, with MAA able to enhance, as well as antagonize, androgenic responses. Moreover, testosterone is shown to exert both positive and negative effects on MAA gene responses. Motif analysis indicated that binding sites for FOX, HOX, LEF/TCF, STAT5 and MEF2 family transcription factors are among the most highly enriched in genes regulated by testosterone and MAA. Notably, 65 FOXO targets were repressed by testosterone or showed repression enhanced by MAA with testosterone; these include 16 genes associated with developmental processes, six of which are Hox genes. CONCLUSIONS These findings highlight the complex interactions between testosterone and MAA, and provide insight into the effects of MAA exposure on androgen-dependent processes in a Leydig cell model.
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Affiliation(s)
- Gargi Bagchi
- Division of Cell and Molecular Biology, Department of Biology, Boston University, Boston, MA 02215, USA
| | - Yijing Zhang
- Division of Cell and Molecular Biology, Department of Biology, Boston University, Boston, MA 02215, USA
| | - Kerri A Stanley
- Division of Cell and Molecular Biology, Department of Biology, Boston University, Boston, MA 02215, USA
| | - David J Waxman
- Division of Cell and Molecular Biology, Department of Biology, Boston University, Boston, MA 02215, USA
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Abstract
The transcription factor FoxG1 regulates neurogenesis in the embryonic telencephalon as well as a number of other neurodevelopmental processes. While FoxG1 continues to be expressed in neurons postnatally and through adulthood, its role in fully differentiated neurons is not known. The current study demonstrates that FoxG1 promotes the survival of postmitotic neurons. In cerebellar granule neurons primed to undergo apoptosis, FoxG1 expression is reduced. Ectopic expression of FoxG1 blocks neuronal death, whereas suppression of its expression induces death in otherwise healthy neurons. The first 36 residues of FoxG1 are necessary for its survival-promoting effect, while the C-terminal half of the protein is dispensable. Mutation of Asp219, a residue necessary for DNA binding, abrogates survival promotion by FoxG1. Survival promotion is also eliminated by mutation of Thr271, a residue phosphorylated by Akt. Pharmacological inhibition of Akt blocks the survival effects of wild-type FoxG1 but not forms in which Thr271 is replaced with phosphomimetic residues. Treatment of neurons with IGF-1, a neurotrophic factor that promotes neuronal survival by activating Akt, prevents the apoptosis-associated downregulation of FoxG1 expression. Moreover, the overexpression of dominant-negative forms of FoxG1 blocks the ability of IGF-1 to maintain neuronal survival suggesting that FoxG1 is a downstream mediator of IGF-1/Akt signaling. Our study identifies a new and important function for FoxG1 in differentiated neurons.
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Petkova TD, Seigel GM, Otteson DC. A role for DNA methylation in regulation of EphA5 receptor expression in the mouse retina. Vision Res 2010; 51:260-8. [PMID: 20875442 DOI: 10.1016/j.visres.2010.09.022] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2010] [Revised: 09/16/2010] [Accepted: 09/17/2010] [Indexed: 01/15/2023]
Abstract
Understanding the mechanisms regulating expression of retinal ganglion cell (RGC) specific and axon-guidance genes during development and in retinal stem cells will be critical for successful optic nerve regeneration. Müller glia have some characteristics of retinal stem cells but in mammals have demonstrated limited potential to differentiate into RGCs. Chromatin remodeling through histone deacetylation and DNA methylation are a potential mechanism for silencing genes necessary for neuronal differentiation of glial cells. We investigated DNA methylation as a mechanism for regulating expression of mouse EphA5, one member of a large family of ephrin receptor genes that regulate patterning of the topographic connections of RGCs during visual system development. We analyzed spatial and age-related patterns of EphA5 promoter methylation by bisulfite sequencing and mRNA expression by quantitative RT-PCR in the mouse retina. The CpG island in the EphA5 promoter was hypomethylated in the retina and showed no change in overall methylation with age, despite a decline in EphA5 mRNA expression levels in the adult retina. In the nasal retina of post-natal day 0 mice, there was a modest, but statistically significant increase in methylation. Increased methylation corresponded with lower levels of receptor mRNA expression in the nasal retina. We cloned the EphA5 promoter and found that site-specific differences in methylation could preferentially activate or repress promoter activity in transient transfections of rat retinal progenitor cells (R28) using luciferase assays. In sphere cultures generated by EGF/FGF2 stimulation of conditionally immortalized mouse Müller glia (ImM10), EphA5 promoter was hypermethylated and EphA5 mRNA was not detected. Demethylation using 5-azadeoxycytidine (AzadC) resulted in a significant decrease of methylation of the EphA5 promoter and re-expression of the EphA5 mRNA. The inverse relationship between EphA5 promoter methylation and mRNA expression is consistent with a role for DNA methylation in modulating the spatial patterns of EphA5 gene expression in the retina and in silencing EphA5 expression in ImM10 cells. The robust up-regulation of EphA5 in ImM10 cells following demethylation suggests that modulation of chromatin structure may be a useful approach for promoting expression of silenced developmental genes and increasing the neurogenic potential of Müller glia.
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Affiliation(s)
- Tihomira D Petkova
- Department of Vision Science, College of Optometry, Houston, TX 77204-2020, USA.
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Wauthier V, Sugathan A, Meyer RD, Dombkowski AA, Waxman DJ. Intrinsic sex differences in the early growth hormone responsiveness of sex-specific genes in mouse liver. Mol Endocrinol 2010; 24:667-78. [PMID: 20150183 PMCID: PMC2840812 DOI: 10.1210/me.2009-0454] [Citation(s) in RCA: 66] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2009] [Accepted: 12/30/2009] [Indexed: 11/19/2022] Open
Abstract
Sex differences in liver gene expression are dictated by sex differences in circulating GH profiles. Presently, the pituitary hormone dependence of mouse liver gene expression was investigated on a global scale to discover sex-specific early GH response genes that could contribute to sex-specific regulation of downstream GH targets and to ascertain whether intrinsic sex differences characterize hepatic responses to plasma GH stimulation. Global RNA expression analysis identified two distinct classes of sex-specific mouse liver genes: genes subject to positive regulation (class I) and genes subject to negative regulation by pituitary hormones (class II). Genes activated or repressed in hypophysectomized (Hypox) mouse liver within 30-90 min of GH pulse treatment at a physiological dose were identified as putative direct targets of GH action (early response genes). Intrinsic sex differences in the GH responsiveness of a subset of these early response genes were observed. Notably, 45 male-specific genes, including five encoding transcriptional regulators that may mediate downstream sex-specific transcriptional responses, were induced by GH within 30 min in Hypox male but not Hypox female mouse liver. The early GH response genes were enriched in 29 male-specific targets of the transcription factor myocyte enhancer factor 2, whose activation in hepatic stellate cells is associated with liver fibrosis leading to hepatocellular carcinoma, a male-predominant disease. Thus, the rapid activation by GH pulses of certain sex-specific genes is modulated by intrinsic sex-specific factors, which may be associated with prior hormone exposure (epigenetic mechanisms) or genetic factors that are pituitary-independent, and could contribute to sex differences in predisposition to liver cancer or other hepatic patho-physiologies.
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Affiliation(s)
- Valerie Wauthier
- Division of Cell and Molecular Biology, Department of Biology, Boston University, Boston, Massachusetts 02215, USA
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Overexpression of FOXG1 contributes to TGF-beta resistance through inhibition of p21WAF1/CIP1 expression in ovarian cancer. Br J Cancer 2009; 101:1433-43. [PMID: 19755996 PMCID: PMC2768441 DOI: 10.1038/sj.bjc.6605316] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
Background: Loss of growth inhibitory response to transforming growth factor-β (TGF-β) is a common feature of epithelial cancers. Recent studies have reported that genetic lesions and overexpression of oncoproteins in TGF-β/Smads signalling cascade contribute to the TGF-β resistance. Here, we showed that the overexpressed FOXG1 was involved in attenuating the anti-proliferative control of TGF-β/Smads signalling in ovarian cancer. Methods: FOXG1 and p21WAF1/CIP1 expressions were evaluated by real-time quantitative reverse-transcription polymerase chain reaction (RT–PCR), western blot and immunohistochemical analyses. The effect of FOXG1 on p21WAF1/CIP1 transcriptional activity was examined by luciferase reporter assays. Cell lines stably expressing or short hairpin RNA interference-mediated knockdown FOXG1 were established for studying the gain-or-loss functional effects of FOXG1. XTT cell proliferation assay was used to measure cell growth of ovarian cancer cells. Results: Quantitative RT–PCR and western blot analyses showed that FOXG1 was upregulated and inversely associated with the expression levels of p21WAF1/CIP1 in ovarian cancer. The overexpression of FOXG1 was significantly correlated with high-grade ovarian cancer (P=0.025). Immunohistochemical analysis on ovarian cancer tissue array was further evidenced that FOXG1 was highly expressed and significantly correlated with high-grade ovarian cancer (P=0.048). Functionally, enforced expression of FOXG1 selectively blocked the TGF-β-induced p21WAF1/CIP1 expressions and increased cell proliferation in ovarian cancer cells. Conversely, FOXG1 knockdown resulted in a 20–26% decrease in cell proliferation together with 16–33% increase in p21WAF1/CIP1 expression. Notably, FOXG1 was able to inhibit the p21WAF1/CIP1 promoter activity in a p53-independent manner by transient reporter assays. Conclusion Our results suggest that FOXG1 acts as an oncoprotein inhibiting TGF-β-mediated anti-proliferative responses in ovarian cancer cells through suppressing p21WAF1/CIP1 transcription.
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Abstract
Athletes and bodybuilders have recognized for several decades that the use of anabolic steroids can promote muscle growth and strength but it is only relatively recently that these agents are being revisited for clinical purposes. Anabolic steroids are being considered for the treatment of cachexia associated with chronic disease states, and to address loss of muscle mass in the elderly, but nevertheless their efficacy still needs to be demonstrated in terms of improved physical function and quality of life. In sport, these agents are performance enhancers, this being particularly apparent in women, although there is a high risk of virilization despite the favourable myotrophic-androgenic dissociation that many xenobiotic steroids confer. Modulation of androgen receptor expression appears to be key to partial dissociation, with consideration of both intracellular steroid metabolism and the topology of the bound androgen receptor interacting with co-activators. An anticatabolic effect, by interfering with glucocorticoid receptor expression, remains an attractive hypothesis. Behavioural changes by non-genomic and genomic pathways probably help motivate training. Anabolic steroids continue to be the most common adverse finding in sport and, although apparently rare, designer steroids have been synthesized in an attempt to circumvent the dope test. Doping with anabolic steroids can result in damage to health, as recorded meticulously in the former German Democratic Republic. Even so, it is important not to exaggerate the medical risks associated with their administration for sporting or bodybuilding purposes but to emphasize to users that an attitude of personal invulnerability to their adverse effects is certainly misguided.
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Affiliation(s)
- A T Kicman
- King's College London, Drug Control Centre, Department of Forensic Science and Drug Monitoring, London, UK.
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