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Liu H, Dang R, Zhang W, Hong J, Li X. SNARE proteins: Core engines of membrane fusion in cancer. Biochim Biophys Acta Rev Cancer 2024:189148. [PMID: 38960006 DOI: 10.1016/j.bbcan.2024.189148] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/29/2024] [Revised: 06/23/2024] [Accepted: 06/27/2024] [Indexed: 07/05/2024]
Abstract
Vesicles are loaded with a variety of cargoes, including membrane proteins, secreted proteins, signaling molecules, and various enzymes, etc. Not surprisingly, vesicle transport is essential for proper cellular life activities including growth, division, movement and cellular communication. Soluble N-ethylmaleimide-sensitive factor attachment protein receptors (SNAREs) mediate membrane fusion of vesicles with their target compartments that is fundamental for cargo delivery. Recent studies have shown that multiple SNARE family members are aberrantly expressed in human cancers and actively contribute to malignant proliferation, invasion, metastasis, immune evasion and treatment resistance. Here, the localization and function of SNARE proteins in eukaryotic cells are firstly mapped. Then we summarize the expression and regulation of SNAREs in cancer, and describe their contribution to cancer progression and mechanisms, and finally we propose engineering botulinum toxin as a strategy to target SNAREs for cancer treatment.
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Affiliation(s)
- Hongyi Liu
- Department of Neurosurgery, Xiangya Hospital, Central South University, Changsha, China; Hunan International Scientific and Technological Cooperation Base of Brain Tumor Research, Xiangya Hospital, Central South University, Changsha, China
| | - Ruiyue Dang
- Department of Oncology, Xiangya Hospital, Central South University, Changsha, China
| | - Wei Zhang
- Department of Neurosurgery, Xiangya Hospital, Central South University, Changsha, China; Hunan International Scientific and Technological Cooperation Base of Brain Tumor Research, Xiangya Hospital, Central South University, Changsha, China
| | - Jidong Hong
- Department of Oncology, Xiangya Hospital, Central South University, Changsha, China.
| | - Xuejun Li
- Department of Neurosurgery, Xiangya Hospital, Central South University, Changsha, China; Hunan International Scientific and Technological Cooperation Base of Brain Tumor Research, Xiangya Hospital, Central South University, Changsha, China.
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2
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Huang L, Zhong X, Li A, Tu F, He M, Xu X, Liu X, Zeng X, Chi J, Tian T, Wang C, Wang X, Ye J. Syntaxin6 contributes to hepatocellular carcinoma tumorigenesis via enhancing STAT3 phosphorylation. Cancer Cell Int 2024; 24:197. [PMID: 38834986 DOI: 10.1186/s12935-024-03377-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2024] [Accepted: 05/17/2024] [Indexed: 06/06/2024] Open
Abstract
BACKGROUND Syntaxin6 (STX6) is a SNARE (Soluble N-ethylmaleimide-sensitive factor attachment protein receptors) protein complex located in the trans-Golgi network and endosomes, which is closely associated with a variety of intracellular membrane transport events. STX6 has been shown to be overexpressed in a variety of human malignant tumors such as esophageal, colorectal, and renal cell carcinomas, and participates in tumorigenesis and development. METHODS Based on clinical public database and clinical liver samples analysis, the expression of STX6 in hepatocellular carcinoma (HCC) tissues was investigated. The effects of STX6 on proliferation, migration and invasion of HCC cell in vitro and in vivo were evaluated through gain- and loss-of-function studies. We further performed RNA-seq analysis and protein interactome analysis, to further decifer the detailed mechanisms of STX6 in the regulation of the JAK-STAT pathway in HCC. RESULTS STX6 expression was upregulated in HCC tissues and its expression was highly correlated with the high histological grade of the tumor. STX6 promoted HCC cell proliferation, migration and invasion both in vitro and in vivo. Mechanistically, STX6 mediated tumor progression depending on promoting the activation of JAK-STAT signaling pathway. Receptor for activated protein kinase C (RACK1) as an essential adaptor protein mediating STX6 regulation of JAK-STAT pathway. Specifically, STX6 interacted with RACK1 and then recruited signal transducer and activator of transcription 3 (STAT3) to form a protein-binding complex and activates STAT3 transcriptional activity. CONCLUSIONS This study provided a novel concept that STX6 exerted oncogenic effects by activating the STAT3 signaling pathway, and STX6 might be a promising therapeutic target for HCC.
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Affiliation(s)
- Li Huang
- Department of oncology, First Affiliated Hospital, Gannan Medical University, Ganzhou, China
- Jiangxi Clinical Medical Research Center for Cancer, Ganzhou, China
| | - Xiaoting Zhong
- Department of oncology, First Affiliated Hospital, Gannan Medical University, Ganzhou, China
- Jiangxi Clinical Medical Research Center for Cancer, Ganzhou, China
| | - An Li
- Department of oncology, First Affiliated Hospital, Gannan Medical University, Ganzhou, China
- Jiangxi Clinical Medical Research Center for Cancer, Ganzhou, China
| | - Fuping Tu
- Department of oncology, First Affiliated Hospital, Gannan Medical University, Ganzhou, China
- Jiangxi Clinical Medical Research Center for Cancer, Ganzhou, China
| | - Miao He
- Department of oncology, First Affiliated Hospital, Gannan Medical University, Ganzhou, China
- Jiangxi Clinical Medical Research Center for Cancer, Ganzhou, China
| | - Xueming Xu
- Department of oncology, First Affiliated Hospital, Gannan Medical University, Ganzhou, China
- Jiangxi Clinical Medical Research Center for Cancer, Ganzhou, China
| | - Xiaohui Liu
- Department of oncology, First Affiliated Hospital, Gannan Medical University, Ganzhou, China
- Jiangxi Clinical Medical Research Center for Cancer, Ganzhou, China
| | - Xiaoli Zeng
- Department of oncology, First Affiliated Hospital, Gannan Medical University, Ganzhou, China
- Jiangxi Clinical Medical Research Center for Cancer, Ganzhou, China
| | - Jun Chi
- Department of oncology, First Affiliated Hospital, Gannan Medical University, Ganzhou, China
- Jiangxi Clinical Medical Research Center for Cancer, Ganzhou, China
| | - Tian Tian
- Gannan Innovation and Translational Medicine Research Institute, Gannan Medical University, Ganzhou, China
| | - Chunli Wang
- Department of critical medicine, First Affiliated Hospital, Gannan Medical University, Ganzhou, China
| | - Xiangcai Wang
- Department of oncology, First Affiliated Hospital, Gannan Medical University, Ganzhou, China.
- Jiangxi Clinical Medical Research Center for Cancer, Ganzhou, China.
- , 128 Jinling Road, Ganzhou City, Jiangxi Province, 341000, China.
| | - Jianming Ye
- Department of oncology, First Affiliated Hospital, Gannan Medical University, Ganzhou, China.
- Jiangxi Clinical Medical Research Center for Cancer, Ganzhou, China.
- , 128 Jinling Road, Ganzhou City, Jiangxi Province, 341000, China.
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Cao W, Ren Y, Liu Y, Cao G, Chen Z, Wang F. KDM4A-AS1 Promotes Cell Proliferation, Migration, and Invasion via the miR-4306/STX6 Axis in Hepatocellular Carcinoma. Crit Rev Eukaryot Gene Expr 2024; 34:55-68. [PMID: 38505873 DOI: 10.1615/critreveukaryotgeneexpr.2024051414] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/21/2024]
Abstract
As a primary liver malignancy, hepatocellular carcinoma (HCC) is commonly induced by chronic liver disease and cirrhosis. Bioinformatics analysis reveals that long noncoding RNA KDM4A antisense RNA 1 (KDM4A-AS1) may be aberrantly expressed in HCC and its abnormal expression might influence prognosis in patients. We conducted this study to illustrate the functions and mechanism of KDM4A-AS1 in regulating HCC malignant cell behavior. KD-M4A-AS1, microRNA (miR)-4306 and messenger RNA syntaxin 6 (STX6) expression was examined by reverse transcription-quantitative polymerase chain reaction (RT-qPCR). HCC cell proliferation, apoptosis, migration, and invasion were measured by colony forming assays, flow cytometry, wound healing and Transwell assays. The interaction between genes was verified by RNA immunoprecipitation and luciferase reporter assays. Western blotting was performed to quantify protein expression of STX6 or apoptotic markers. KDM4A-AS1 was highly expressed in HCC cells and tissues. KDM4A-AS1 knockdown led to enhanced HCC cell apoptosis and suppressed HCC cell proliferation, migration, and invasion. MiR-4306 bound to and negatively regulated STX6. KDM4A-AS1 directly bound to miR-4306 and thus up-regulated STX6. STX6 overexpression reversed the inhibitory influence of KDM4A-AS1 depletion on HCC malignant behavior. KDM4A-AS1 promotes HCC cell migration, invasion, and growth by upregulating STX6 via miR-4306.
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Affiliation(s)
- Wei Cao
- Department of Gastroenterology, Renmin Hospital, Hubei University of Medicine, Shiyan 442000, Hubei Province, P.R. China
| | - Yuhan Ren
- Department of Gastroenterology, Renmin Hospital, Hubei University of Medicine, Shiyan 442000, Hubei Province, P.R. China
| | - Ying Liu
- Department of Gastroenterology, Renmin Hospital, Hubei University of Medicine, Shiyan 442000, Hubei Province, P.R. China
| | - Guoshu Cao
- Department of Gastroenterology, Renmin Hospital, Hubei University of Medicine, Shiyan 442000, Hubei Province, P.R. China
| | - Zhen Chen
- Department of Emergency, The Central Hospital of Wuhan, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430000, Hubei Province, P.R. China
| | - Fan Wang
- Renmin Hospital, Hubei University of Medicine
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Li W, Li K, Wei H, Sun Y, Liao Y, Zou Y, Chen X, Deng C, Chen S, He Y, Huo M, Zhang C. Syntaxin-6, a Reliable Biomarker for Predicting the Prognosis of Patients with Cancer and the Effectiveness of Immunotherapy. Cancers (Basel) 2022; 15:cancers15010027. [PMID: 36612024 PMCID: PMC9817965 DOI: 10.3390/cancers15010027] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2022] [Revised: 12/17/2022] [Accepted: 12/18/2022] [Indexed: 12/24/2022] Open
Abstract
Syntaxin-6 (STX6), a vesicular transport protein, is a direct target of the tumor suppressor gene P53, supporting cancer growth dependent on P53. However, STX6's function in the tumor microenvironment has yet to be reported. In this research, we comprehensively explored the role of the oncogene STX6 in pan-cancer by combining data from several databases, including the Cancer Genome Atlas, CPTAC, cBioPortal, and TIMER. Then, we verified the carcinogenic effect of STX6 in hepatocellular carcinoma (HCC) and colorectal cancer (CRC) through a series of experiments in vitro and in vivo. Bioinformatics analysis demonstrated that STX6 is an oncogene for several cancers and is mainly involved in the cell cycle, epithelial-mesenchymal transition, oxidative phosphorylation, and tumor immune modulation, especially for tumor-associated fibroblasts (CAFs) and NKT cells. Additionally, a high level of STX6 could indicate patients' resistance to immunotherapy. Our own data indicated that the STX6 level was upregulated in HCC and CRC. Knockdown of the STX6 levels could arrest the cell cycle and restrain cell proliferation, migration, and invasion. RNA-seq indicated that STX6 was significantly involved in pathways for cancer, such as the MAPK signal pathway. In a mouse model, knockdown of STX6 inhibited tumor growth and potentiated anti-PD-1 efficacy. In light of the essential roles STX6 plays in carcinogenesis and cancer immunology, it has the potential to be a predictive biomarker and a target for cancer immunotherapy.
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Affiliation(s)
- Wenchao Li
- Digestive Diseases Center, The Seventh Affiliated Hospital of Sun Yat-sen University, No. 628 Zhenyuan Road, Shenzhen 518107, China
- Guangdong Provincial Key Laboratory of Digestive Cancer Research, The Seventh Affiliated Hospital of Sun Yat-sen University, No. 628 Zhenyuan Road, Shenzhen 518107, China
| | - Kuan Li
- Digestive Diseases Center, The Seventh Affiliated Hospital of Sun Yat-sen University, No. 628 Zhenyuan Road, Shenzhen 518107, China
- Guangdong Provincial Key Laboratory of Digestive Cancer Research, The Seventh Affiliated Hospital of Sun Yat-sen University, No. 628 Zhenyuan Road, Shenzhen 518107, China
| | - Hongfa Wei
- Digestive Diseases Center, The Seventh Affiliated Hospital of Sun Yat-sen University, No. 628 Zhenyuan Road, Shenzhen 518107, China
- Guangdong Provincial Key Laboratory of Digestive Cancer Research, The Seventh Affiliated Hospital of Sun Yat-sen University, No. 628 Zhenyuan Road, Shenzhen 518107, China
| | - Yu Sun
- Digestive Diseases Center, The Seventh Affiliated Hospital of Sun Yat-sen University, No. 628 Zhenyuan Road, Shenzhen 518107, China
- Guangdong Provincial Key Laboratory of Digestive Cancer Research, The Seventh Affiliated Hospital of Sun Yat-sen University, No. 628 Zhenyuan Road, Shenzhen 518107, China
| | - Yangjing Liao
- Department of Traditional Chinese Medicine, The Third Affiliated Hospital of Sun Yat-sen University, Guangzhou 510000, China
| | - Yuan Zou
- Department of Pathology, Southern Hospital, Southern Medical University, Guangzhou 510000, China
| | - Xiancong Chen
- Digestive Diseases Center, The Seventh Affiliated Hospital of Sun Yat-sen University, No. 628 Zhenyuan Road, Shenzhen 518107, China
- Guangdong Provincial Key Laboratory of Digestive Cancer Research, The Seventh Affiliated Hospital of Sun Yat-sen University, No. 628 Zhenyuan Road, Shenzhen 518107, China
| | - Cuncan Deng
- Digestive Diseases Center, The Seventh Affiliated Hospital of Sun Yat-sen University, No. 628 Zhenyuan Road, Shenzhen 518107, China
- Guangdong Provincial Key Laboratory of Digestive Cancer Research, The Seventh Affiliated Hospital of Sun Yat-sen University, No. 628 Zhenyuan Road, Shenzhen 518107, China
| | - Songyao Chen
- Digestive Diseases Center, The Seventh Affiliated Hospital of Sun Yat-sen University, No. 628 Zhenyuan Road, Shenzhen 518107, China
- Guangdong Provincial Key Laboratory of Digestive Cancer Research, The Seventh Affiliated Hospital of Sun Yat-sen University, No. 628 Zhenyuan Road, Shenzhen 518107, China
| | - Yulong He
- Digestive Diseases Center, The Seventh Affiliated Hospital of Sun Yat-sen University, No. 628 Zhenyuan Road, Shenzhen 518107, China
- Guangdong Provincial Key Laboratory of Digestive Cancer Research, The Seventh Affiliated Hospital of Sun Yat-sen University, No. 628 Zhenyuan Road, Shenzhen 518107, China
| | - Mingyu Huo
- Digestive Diseases Center, The Seventh Affiliated Hospital of Sun Yat-sen University, No. 628 Zhenyuan Road, Shenzhen 518107, China
- Guangdong Provincial Key Laboratory of Digestive Cancer Research, The Seventh Affiliated Hospital of Sun Yat-sen University, No. 628 Zhenyuan Road, Shenzhen 518107, China
- Correspondence: (M.H.); (C.Z.)
| | - Changhua Zhang
- Digestive Diseases Center, The Seventh Affiliated Hospital of Sun Yat-sen University, No. 628 Zhenyuan Road, Shenzhen 518107, China
- Guangdong Provincial Key Laboratory of Digestive Cancer Research, The Seventh Affiliated Hospital of Sun Yat-sen University, No. 628 Zhenyuan Road, Shenzhen 518107, China
- Correspondence: (M.H.); (C.Z.)
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Oscilowska I, Huynh TYL, Baszanowska W, Prokop I, Surazynski A, Galli M, Zabielski P, Palka J. Proline oxidase silencing inhibits p53-dependent apoptosis in MCF-7 breast cancer cells. Amino Acids 2021; 53:1943-1956. [PMID: 34085157 PMCID: PMC8651586 DOI: 10.1007/s00726-021-03013-8] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2021] [Accepted: 05/28/2021] [Indexed: 02/02/2023]
Abstract
Proline oxidase (POX) is mitochondrial proline-degrading enzyme of dual apoptosis/survival function. POX expression and proline availability are considered an underlying mechanism for differential POX functions. The mechanism for POX-dependent regulation of cell death/survival was studied in wild-type (MCF-7WT) and shRNA POX-silenced breast cancer cells (MCF-7iPOX). Proline concentration and proteomic analyses were determined by LC/MS/QTOF and LC/MS/ORBITRA, respectively. Inhibition of collagen biosynthesis (proline utilizing process) by 2-methoxyestradiol (2ME) contributed to induction of apoptosis in MCF-7WT cells, as detected by increase in the expression of active caspase-3, -9 and p53. The process was not shown in MCF-7iPOX. In MCF-7iPOX cells prolidase activity and expression as well as proline concentration were drastically increased, compared to MCF-7WT cells. Down-regulation of p53 in MCF-7iPOX cells was corroborated by proteomic analysis showing decrease in the expression of p53-related proteins. The mechanism for down-regulation of p53 expression in MCF-7iPOX cells was found at the level of p53-PEPD complex formation that was counteracted by hydrogen peroxide treatment. In this study, we found that silencing POX modulate pro-survival phenotype of MCF-7 cells and suggest that the mechanism of this process undergoes through down-regulation of p53-dependent signaling.
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Affiliation(s)
- Ilona Oscilowska
- Department of Medicinal Chemistry, Medical University of Bialystok, Mickiewicza 2D, 15-222, Bialystok, Poland
| | - Thi Y L Huynh
- Department of Medicinal Chemistry, Medical University of Bialystok, Mickiewicza 2D, 15-222, Bialystok, Poland
| | - Weronika Baszanowska
- Department of Medicinal Chemistry, Medical University of Bialystok, Mickiewicza 2D, 15-222, Bialystok, Poland
| | - Izabela Prokop
- Department of Medicinal Chemistry, Medical University of Bialystok, Mickiewicza 2D, 15-222, Bialystok, Poland
| | - Arkadiusz Surazynski
- Department of Medicinal Chemistry, Medical University of Bialystok, Mickiewicza 2D, 15-222, Bialystok, Poland
| | - Mauro Galli
- Department of Medical Biology, Medical University of Bialystok, Mickiewicza 2C, 15-222, Bialystok, Poland
| | - Piotr Zabielski
- Department of Medical Biology, Medical University of Bialystok, Mickiewicza 2C, 15-222, Bialystok, Poland
| | - Jerzy Palka
- Department of Medicinal Chemistry, Medical University of Bialystok, Mickiewicza 2D, 15-222, Bialystok, Poland.
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Peak TC, Panigrahi GK, Praharaj P, Su Y, Shi L, Chyr J, Rivera-Chávez J, Flores-Bocanegra L, Singh R, Vander Griend DJ, Oberlies NH, Kerr BA, Hemal A, Bitting RL, Deep G. Syntaxin 6-mediated exosome secretion regulates enzalutamide resistance in prostate cancer. Mol Carcinog 2020; 59:62-72. [PMID: 31674708 PMCID: PMC6916724 DOI: 10.1002/mc.23129] [Citation(s) in RCA: 39] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2019] [Revised: 10/16/2019] [Accepted: 10/17/2019] [Indexed: 12/12/2022]
Abstract
Prostate cancer (PCa) deaths are typically the result of metastatic castration-resistant PCa (mCRPC). Recently, enzalutamide (Enz), an oral androgen receptor inhibitor, was approved for treating patients with mCRPC. Invariably, all PCa patients eventually develop resistance against Enz. Therefore, novel strategies aimed at overcoming Enz resistance are needed to improve the survival of PCa patients. The role of exosomes in drug resistance has not been fully elucidated in PCa. Therefore, we set out to better understand the exosome's role in the mechanism underlying Enz-resistant PCa. Results showed that Enz-resistant PCa cells (C4-2B, CWR-R1, and LNCaP) secreted significantly higher amounts of exosomes (2-4 folds) compared to Enz-sensitive counterparts. Inhibition of exosome biogenesis in resistant cells by GW4869 and dimethyl amiloride strongly decreased their cell viability. Mechanistic studies revealed upregulation of syntaxin 6 as well as its increased colocalization with CD63 in Enz-resistant PCa cells compared to Enz-sensitive cells. Syntaxin 6 knockdown by specific small interfering RNAs in Enz-resistant PCa cells (C4-2B and CWR-R1) resulted in reduced cell number and increased cell death in the presence of Enz. Furthermore, syntaxin 6 knockdown significantly reduced the exosome secretion in both Enz-resistant C4-2B and CWR-R1 cells. The Cancer Genome Atlas analysis showed increased syntaxin 6 expressions associated with higher Gleason score and decreased progression-free survival in PCa patients. Importantly, IHC analysis showed higher syntaxin 6 expression in cancer tissues from Enz-treated patients compared to Enz naïve patients. Overall, syntaxin 6 plays an important role in the secretion of exosomes and increased survival of Enz-resistant PCa cells.
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Affiliation(s)
- Taylor C. Peak
- Department of Cancer Biology, Wake Forest School of Medicine, Winston-Salem, North Carolina
| | - Gati K Panigrahi
- Department of Cancer Biology, Wake Forest School of Medicine, Winston-Salem, North Carolina
| | - Prakash Praharaj
- Department of Cancer Biology, Wake Forest School of Medicine, Winston-Salem, North Carolina
| | - Yixin Su
- Department of Cancer Biology, Wake Forest School of Medicine, Winston-Salem, North Carolina
| | - Lihong Shi
- Department of Cancer Biology, Wake Forest School of Medicine, Winston-Salem, North Carolina
| | - Jacqueline Chyr
- School of Bioinformatics, University of Texas Health Science Center, Houston, Texas
| | - José Rivera-Chávez
- Department of Chemistry and Biochemistry, University of North Carolina at Greensboro; Greensboro, North Carolina
| | - Laura Flores-Bocanegra
- Department of Chemistry and Biochemistry, University of North Carolina at Greensboro; Greensboro, North Carolina
| | - Ravi Singh
- Department of Cancer Biology, Wake Forest School of Medicine, Winston-Salem, North Carolina
| | | | - Nicholas H. Oberlies
- Department of Chemistry and Biochemistry, University of North Carolina at Greensboro; Greensboro, North Carolina
| | - Bethany A. Kerr
- Department of Cancer Biology, Wake Forest School of Medicine, Winston-Salem, North Carolina
- Wake Forest Baptist Comprehensive Cancer Center
- Department of Urology
| | | | - Rhonda L. Bitting
- Internal Medicine-Hematology and Oncology, Wake Forest School of Medicine, Winston-Salem, North Carolina
| | - Gagan Deep
- Department of Cancer Biology, Wake Forest School of Medicine, Winston-Salem, North Carolina
- Wake Forest Baptist Comprehensive Cancer Center
- Department of Urology
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Syntaxin 6: A novel predictive and prognostic biomarker in papillary renal cell carcinoma. Sci Rep 2019; 9:3146. [PMID: 30816681 PMCID: PMC6395695 DOI: 10.1038/s41598-019-39305-z] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2018] [Accepted: 01/07/2019] [Indexed: 12/20/2022] Open
Abstract
Syntaxin 6 is a SNARE family protein known to play an important role in intracellular trafficking. Here, we examined the tumorogenic role of syntaxin 6 in renal cell carcinoma (RCC). The Cancer Genome Atlas (TCGA) was queried for clinicopathologic data and syntaxin 6 expression. We found a significant difference in overall survival (OS) between groups, with high syntaxin 6 expression correlating with decreased survival. When stratifying the data based on histological subtype, the papillary RCC subtype exhibited a significant correlation between syntaxin 6 expression and survival. Using ROC curve, we calculated the area under the curve (AUC) to determine the ability of syntaxin 6 to predict 3-year overall survival. The AUC for syntaxin 6 was 0.73, significantly higher compared to 0.52 for T stage. Next, syntaxin 6 expression was evaluated in clear cell (786-O and Caki-1) and papillary (Caki-2 and ACHN) RCC cells. Syntaxin 6 expression was higher in Caki-1 and ACHN RCC cells. Silencing of syntaxin 6 in ACHN cells significantly decreased the cell viability (p < 0.001). Overall, syntaxin 6 could be a prognostic biomarker for patients with papillary RCC and syntaxin 6 inhibitors hold promise as a novel therapy against RCC.
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Du J, Liu X, Wu Y, Zhu J, Tang Y. Essential role of STX6 in esophageal squamous cell carcinoma growth and migration. Biochem Biophys Res Commun 2016; 472:60-7. [PMID: 26906622 DOI: 10.1016/j.bbrc.2016.02.061] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2016] [Accepted: 02/15/2016] [Indexed: 11/15/2022]
Abstract
Abnormalities in endosomes, or dysregulation in their trafficking, play an important role directly in many diseases including oncogenesis. Syntaxin-6 (STX6) is involved in diverse cellular functions in a variety of cell types and has been shown to regulate many intracellular membrane trafficking events such as endocytosis, recycling and anterograde and retrograde trafficking. However, its expression pattern and biological functions in esophageal squamous cell carcinoma (ESCC) remained unknown. Here, we have found that the expression of STX6 was up-regulated in ESCC samples, its expression was significantly correlated with tumor size, histological differentiation, lymph node metastasis and depth. On one hand, STX6 silencing inhibited ESCC cells viability and proliferation in a p53-dependent manner. On the other hand, STX6 effect integrin trafficking and regulate ESCC cells migration. Taken together, our study revealed the oncogenic roles of STX6 in the progression of ESCC, and it might be a valuable target for ESCC therapy.
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Affiliation(s)
- Jin Du
- Department of Cardiothoracic Surgery, The First Affiliated Hospital with Nanjing Medical University, Nanjing 210029, China; Affiliated Hospital of Integrated Traditional Chinese and Western Medicine, Nanjing University of Chinese Medicine, Nanjing 210028, China
| | - Xiang Liu
- Department of Cardiothoracic Surgery, The First Affiliated Hospital with Nanjing Medical University, Nanjing 210029, China
| | - Yanhu Wu
- Department of Cardiothoracic Surgery, The First Affiliated Hospital with Nanjing Medical University, Nanjing 210029, China.
| | - Jinfu Zhu
- Department of Cardiothoracic Surgery, The First Affiliated Hospital with Nanjing Medical University, Nanjing 210029, China
| | - Yihu Tang
- Department of Cardiothoracic Surgery, The First Affiliated Hospital with Nanjing Medical University, Nanjing 210029, China
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Abstract
The predominant function of the tumor suppressor p53 is transcriptional regulation. It is generally accepted that p53-dependent transcriptional activation occurs by binding to a specific recognition site in promoters of target genes. Additionally, several models for p53-dependent transcriptional repression have been postulated. Here, we evaluate these models based on a computational meta-analysis of genome-wide data. Surprisingly, several major models of p53-dependent gene regulation are implausible. Meta-analysis of large-scale data is unable to confirm reports on directly repressed p53 target genes and falsifies models of direct repression. This notion is supported by experimental re-analysis of representative genes reported as directly repressed by p53. Therefore, p53 is not a direct repressor of transcription, but solely activates its target genes. Moreover, models based on interference of p53 with activating transcription factors as well as models based on the function of ncRNAs are also not supported by the meta-analysis. As an alternative to models of direct repression, the meta-analysis leads to the conclusion that p53 represses transcription indirectly by activation of the p53-p21-DREAM/RB pathway.
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Key Words
- CDE, cell cycle-dependent element
- CDKN1A
- CHR, cell cycle genes homology region
- ChIP, chromatin immunoprecipitation
- DREAM complex
- DREAM, DP, RB-like, E2F4, and MuvB complex
- E2F/RB complex
- HPV, human papilloma virus
- NF-Y, Nuclear factor Y
- cdk, cyclin-dependent kinase
- genome-wide meta-analysis
- p53
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Affiliation(s)
- Martin Fischer
- a Molecular Oncology; Medical School ; University of Leipzig ; Leipzig , Germany
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Zhao S, Niu F, Xu CY, Ye L, Bi GB, Chen L, Gong P, Tian G, Nie TH. Microarray and ChIP-seq data analysis revealed changes in p53-mediated transcriptional regulation in Nutlin-3-treated U2OS cells. Mol Med Rep 2015; 12:4284-4290. [PMID: 26080812 PMCID: PMC4526040 DOI: 10.3892/mmr.2015.3933] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2014] [Accepted: 05/27/2015] [Indexed: 01/10/2023] Open
Abstract
Integrative analysis of chromatin immunoprecipitation-sequencing (ChIP-seq) data and microarray data was performed to illustrate the effect of Nutlin‑3 on promoter selectivity and transcriptional regulation by the tumor suppressor p53 in U2OS human osteosarcoma cells. Raw data (accession number, GSE46642) were downloaded from Gene Expression Omnibus. Differential analyses were performed using package limma of R software. Gene ontology enrichment and Kyoto Encyclopedia of Genes and Genomes pathway enrichment analyses were performed for the differentially expressed genes (DEGs) using the Database for Annotation, Visualization and Integration Discovery. Integrative analysis of ChIP‑seq data and microarray data were confirmed with ChIP‑Array. A total of 565 DEGs were identified, including 373 upregulated genes and 192 downregulated genes. Genes involved in the p53 signaling pathway, cell cycle, DNA replication, cytokine‑cytokine receptor interaction and melanoma were markedly over‑represented in the DEGs. A total of 39 DEGs were directly regulated by p53 and two were the transcription factors (TFs), E2F2 and HOXA1. E2F2 regulated 25 DEGs, while HOXA1 regulated one DEG. The cell cycle, p53 signaling pathway, melanoma and pathways involved in cancer were enriched in the direct and indirect target genes. Changes in the p53‑binding pattern induced by Nutlin‑3 were described in the present study, which may advance the understanding of the regulatory network of p53 in osteosarcoma and aid in the development of novel therapies.
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Affiliation(s)
- Song Zhao
- Department of Spinal Surgery, The First Hospital of Jilin University, Changchun, Jilin 130021, P.R. China
| | - Feng Niu
- Department of Spinal Surgery, The First Hospital of Jilin University, Changchun, Jilin 130021, P.R. China
| | - Chang-Yan Xu
- Department of Medical Records, The First Hospital of Jilin University, Changchun, Jilin 130021, P.R. China
| | - Long Ye
- Department of Spinal Surgery, The First Hospital of Jilin University, Changchun, Jilin 130021, P.R. China
| | - Gui-Bin Bi
- Department of Spinal Surgery, The First Hospital of Jilin University, Changchun, Jilin 130021, P.R. China
| | - Lin Chen
- Department of Spinal Surgery, The First Hospital of Jilin University, Changchun, Jilin 130021, P.R. China
| | - Ping Gong
- Department of Spinal Surgery, The First Hospital of Jilin University, Changchun, Jilin 130021, P.R. China
| | - Gang Tian
- Department of Spinal Surgery, The First Hospital of Jilin University, Changchun, Jilin 130021, P.R. China
| | - Tian-Hong Nie
- Department of Spinal Surgery, The First Hospital of Jilin University, Changchun, Jilin 130021, P.R. China
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11
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Reverter M, Rentero C, Garcia-Melero A, Hoque M, Vilà de Muga S, Alvarez-Guaita A, Conway JRW, Wood P, Cairns R, Lykopoulou L, Grinberg D, Vilageliu L, Bosch M, Heeren J, Blasi J, Timpson P, Pol A, Tebar F, Murray RZ, Grewal T, Enrich C. Cholesterol regulates Syntaxin 6 trafficking at trans-Golgi network endosomal boundaries. Cell Rep 2014; 7:883-97. [PMID: 24746815 DOI: 10.1016/j.celrep.2014.03.043] [Citation(s) in RCA: 86] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2013] [Revised: 12/30/2013] [Accepted: 03/17/2014] [Indexed: 12/27/2022] Open
Abstract
Inhibition of cholesterol export from late endosomes causes cellular cholesterol imbalance, including cholesterol depletion in the trans-Golgi network (TGN). Here, using Chinese hamster ovary (CHO) Niemann-Pick type C1 (NPC1) mutant cell lines and human NPC1 mutant fibroblasts, we show that altered cholesterol levels at the TGN/endosome boundaries trigger Syntaxin 6 (Stx6) accumulation into VAMP3, transferrin, and Rab11-positive recycling endosomes (REs). This increases Stx6/VAMP3 interaction and interferes with the recycling of αVβ3 and α5β1 integrins and cell migration, possibly in a Stx6-dependent manner. In NPC1 mutant cells, restoration of cholesterol levels in the TGN, but not inhibition of VAMP3, restores the steady-state localization of Stx6 in the TGN. Furthermore, elevation of RE cholesterol is associated with increased amounts of Stx6 in RE. Hence, the fine-tuning of cholesterol levels at the TGN-RE boundaries together with a subset of cholesterol-sensitive SNARE proteins may play a regulatory role in cell migration and invasion.
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Affiliation(s)
- Meritxell Reverter
- Departament de Biologia Cel·lular, Immunologia i Neurociències, Facultat de Medicina, Universitat de Barcelona, 08036 Barcelona, Spain
| | - Carles Rentero
- Departament de Biologia Cel·lular, Immunologia i Neurociències, Facultat de Medicina, Universitat de Barcelona, 08036 Barcelona, Spain
| | - Ana Garcia-Melero
- Departament de Biologia Cel·lular, Immunologia i Neurociències, Facultat de Medicina, Universitat de Barcelona, 08036 Barcelona, Spain
| | - Monira Hoque
- Faculty of Pharmacy, University of Sydney, Sydney, NSW 2006, Australia
| | - Sandra Vilà de Muga
- Departament de Biologia Cel·lular, Immunologia i Neurociències, Facultat de Medicina, Universitat de Barcelona, 08036 Barcelona, Spain
| | - Anna Alvarez-Guaita
- Departament de Biologia Cel·lular, Immunologia i Neurociències, Facultat de Medicina, Universitat de Barcelona, 08036 Barcelona, Spain
| | - James R W Conway
- Garvan Institute of Medical Research and Kinghorn Cancer Centre, Cancer Research Program, St. Vincent's Clinical School, Faculty of Medicine, University of New South Wales, Sydney, NSW 2010, Australia
| | - Peta Wood
- Faculty of Pharmacy, University of Sydney, Sydney, NSW 2006, Australia
| | - Rose Cairns
- Faculty of Pharmacy, University of Sydney, Sydney, NSW 2006, Australia
| | - Lilia Lykopoulou
- First Department of Pediatrics, University of Athens, Aghia Sofia Children's Hospital, 11527 Athens, Greece
| | - Daniel Grinberg
- Departament de Genètica, Facultat de Biologia, Universitat de Barcelona, CIBERER, IBUB, 08028 Barcelona, Spain
| | - Lluïsa Vilageliu
- Departament de Genètica, Facultat de Biologia, Universitat de Barcelona, CIBERER, IBUB, 08028 Barcelona, Spain
| | - Marta Bosch
- Centre de Recerca Biomèdica CELLEX, Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), 08036 Barcelona, Spain
| | - Joerg Heeren
- Department of Biochemistry and Molecular Biology II. Molecular Cell Biology, University Medical Center Hamburg-Eppendorf, 20246 Hamburg, Germany
| | - Juan Blasi
- Department of Pathology and Experimental Therapeutics, IDIBELL-University of Barcelona, L'Hospitalet de Llobregat, 08907 Barcelona, Spain
| | - Paul Timpson
- Garvan Institute of Medical Research and Kinghorn Cancer Centre, Cancer Research Program, St. Vincent's Clinical School, Faculty of Medicine, University of New South Wales, Sydney, NSW 2010, Australia
| | - Albert Pol
- Departament de Biologia Cel·lular, Immunologia i Neurociències, Facultat de Medicina, Universitat de Barcelona, 08036 Barcelona, Spain; Centre de Recerca Biomèdica CELLEX, Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), 08036 Barcelona, Spain; Institució Catalana de Recerca i Estudis Avaçats (ICREA), 08010 Barcelona, Spain
| | - Francesc Tebar
- Departament de Biologia Cel·lular, Immunologia i Neurociències, Facultat de Medicina, Universitat de Barcelona, 08036 Barcelona, Spain; Centre de Recerca Biomèdica CELLEX, Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), 08036 Barcelona, Spain
| | - Rachael Z Murray
- Tissue Repair and Regeneration Program, Institute of Health and Biomedical, Innovation, Queensland University of Technology, Brisbane, QLD 4095, Australia
| | - Thomas Grewal
- Faculty of Pharmacy, University of Sydney, Sydney, NSW 2006, Australia.
| | - Carlos Enrich
- Departament de Biologia Cel·lular, Immunologia i Neurociències, Facultat de Medicina, Universitat de Barcelona, 08036 Barcelona, Spain; Centre de Recerca Biomèdica CELLEX, Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), 08036 Barcelona, Spain.
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12
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Chen W, Wang H, Tao S, Zheng Y, Wu W, Lian F, Jaramillo M, Fang D, Zhang DD. Tumor protein translationally controlled 1 is a p53 target gene that promotes cell survival. Cell Cycle 2014; 12:2321-8. [PMID: 24067374 DOI: 10.4161/cc.25404] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Tumor suppressor p53 maintains genome stability by differentially activating target genes that control diverse cellular responses, such as the antioxidant response, cell cycle arrest and apoptosis. Despite the fact that many p53 downstream genes have been well characterized, novel p53 target genes are continuously being identified. Here, we report that Tpt1 is a direct target gene of p53. We found that p53 upregulates the transcription of Tpt1 and identified a p53-responsive element in the promoter of the mouse Tpt1 gene. Furthermore, p53-dependent induction of Tpt1 was able to reduce oxidative stress, minimize apoptosis, and promote cell survival in response to H 2O2 challenge. In addition, a positive correlation between the expression of p53 and Tpt1 only existed in normal lung tissues, not in lung tumors. Such positive correlation was also found in lung cell lines that contain wild-type p53, but not mutated p53. Based on the important role of Tpt1 in cancer development, chemoresistance, and cancer reversion, identification of Tpt1 as a direct target gene of p53 not only adds to the complexity of the p53 network, but may also open up a new avenue for cancer prevention and intervention.
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Affiliation(s)
- Weimin Chen
- Department of Pharmacology & Toxicology, College of Pharmacy, University of Arizona, Tucson, AZ, USA
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13
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Naydenov NG, Feygin A, Wang L, Ivanov AI. N-ethylmaleimide-sensitive factor attachment protein α (αSNAP) regulates matrix adhesion and integrin processing in human epithelial cells. J Biol Chem 2013; 289:2424-39. [PMID: 24311785 DOI: 10.1074/jbc.m113.498691] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Integrin-based adhesion to the extracellular matrix (ECM) plays critical roles in controlling differentiation, survival, and motility of epithelial cells. Cells attach to the ECM via dynamic structures called focal adhesions (FA). FA undergo constant remodeling mediated by vesicle trafficking and fusion. A soluble N-ethylmaleimide-sensitive factor (NSF) attachment protein α (αSNAP) is an essential mediator of membrane fusion; however, its roles in regulating ECM adhesion and cell motility remain unexplored. In this study, we found that siRNA-mediated knockdown of αSNAP induced detachment of intestinal epithelial cells, whereas overexpression of αSNAP increased ECM adhesion and inhibited cell invasion. Loss of αSNAP impaired Golgi-dependent glycosylation and trafficking of β1 integrin and decreased phosphorylation of focal adhesion kinase (FAK) and paxillin resulting in FA disassembly. These effects of αSNAP depletion on ECM adhesion were independent of apoptosis and NSF. In agreement with our previous reports that Golgi fragmentation mediates cellular effects of αSNAP knockdown, we found that either pharmacologic or genetic disruption of the Golgi recapitulated all the effects of αSNAP depletion on ECM adhesion. Furthermore, our data implicates β1 integrin, FAK, and paxillin in mediating the observed pro-adhesive effects of αSNAP. These results reveal novel roles for αSNAP in regulating ECM adhesion and motility of epithelial cells.
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14
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Chukkapalli S, Amessou M, Dekhil H, Dilly AK, Liu Q, Bandyopadhyay S, Thomas RD, Bejna A, Batist G, Kandouz M. Ehd3, a regulator of vesicular trafficking, is silenced in gliomas and functions as a tumor suppressor by controlling cell cycle arrest and apoptosis. Carcinogenesis 2013; 35:877-85. [PMID: 24306026 DOI: 10.1093/carcin/bgt399] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
EHD3 [Eps15 homology (EH) domain-containing protein 3] is a protein that resides in tubular and vesicular membrane structures and participates in endocytic recycling, although all its functions are unknown. Since Ehd3 is most abundantly expressed in brain tissues, we examined its role in brain cancer progression. Using immunohistochemistry, we report loss of EHD3 expression in gliomas, including low-grade astrocytomas, suggesting that this is an early event in gliomagenesis. EHD3 expression is also very low in most of glioma cell lines tested. In two cell lines, a bisulfite sequencing method identifies promoter hypermethylation as a mechanism of Ehd3 silencing, and its expression was restored by the demethylating agent 5-Azacytidine. Doxycycline-inducible restoration of EHD3 expression to glioma cells decreases their growth and invasiveness and induces cell cycle arrest and apoptosis. Furthermore, shRNA-mediated Ehd3 silencing increases cell growth. Using a xenograft model, we demonstrate Ehd3 growth inhibitory functions in glioma cells in vivo. We suggest that Ehd3 functions as a tumor suppressor gene and loss of its expression is a very common event in gliomas. This is the first study to highlight the importance of a member of the C-terminal EHD proteins in cancer and to link their functions to the cell cycle and apoptosis.
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Affiliation(s)
- Sahiti Chukkapalli
- Department of Pathology, Wayne State University School of Medicine, Detroit, MI 48201, USA
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15
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Sanders AR, Göring HHH, Duan J, Drigalenko EI, Moy W, Freda J, He D, Shi J, Gejman PV. Transcriptome study of differential expression in schizophrenia. Hum Mol Genet 2013; 22:5001-14. [PMID: 23904455 DOI: 10.1093/hmg/ddt350] [Citation(s) in RCA: 68] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Schizophrenia genome-wide association studies (GWAS) have identified common SNPs, rare copy number variants (CNVs) and a large polygenic contribution to illness risk, but biological mechanisms remain unclear. Bioinformatic analyses of significantly associated genetic variants point to a large role for regulatory variants. To identify gene expression abnormalities in schizophrenia, we generated whole-genome gene expression profiles using microarrays on lymphoblastoid cell lines (LCLs) from 413 cases and 446 controls. Regression analysis identified 95 transcripts differentially expressed by affection status at a genome-wide false discovery rate (FDR) of 0.05, while simultaneously controlling for confounding effects. These transcripts represented 89 genes with functions such as neurotransmission, gene regulation, cell cycle progression, differentiation, apoptosis, microRNA (miRNA) processing and immunity. This functional diversity is consistent with schizophrenia's likely significant pathophysiological heterogeneity. The overall enrichment of immune-related genes among those differentially expressed by affection status is consistent with hypothesized immune contributions to schizophrenia risk. The observed differential expression of extended major histocompatibility complex (xMHC) region histones (HIST1H2BD, HIST1H2BC, HIST1H2BH, HIST1H2BG and HIST1H4K) converges with the genetic evidence from GWAS, which find the xMHC to be the most significant susceptibility locus. Among the differentially expressed immune-related genes, B3GNT2 is implicated in autoimmune disorders previously tied to schizophrenia risk (rheumatoid arthritis and Graves' disease), and DICER1 is pivotal in miRNA processing potentially linking to miRNA alterations in schizophrenia (e.g. MIR137, the second strongest GWAS finding). Our analysis provides novel candidate genes for further study to assess their potential contribution to schizophrenia.
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Affiliation(s)
- Alan R Sanders
- Department of Psychiatry and Behavioral Sciences, NorthShore University HealthSystem, Evanston, IL 60201, USA
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16
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Zhang Y, Yan W, Jung YS, Chen X. PUMA Cooperates with p21 to Regulate Mammary Epithelial Morphogenesis and Epithelial-To-Mesenchymal Transition. PLoS One 2013; 8:e66464. [PMID: 23805223 PMCID: PMC3689819 DOI: 10.1371/journal.pone.0066464] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2013] [Accepted: 05/06/2013] [Indexed: 12/20/2022] Open
Abstract
Lumen formation is essential for mammary morphogenesis and requires proliferative suppression and apoptotic clearance of the inner cells within developing acini. Previously, we showed that knockdown of p53 or p73 leads to aberrant mammary acinus formation accompanied with decreased expression of p53 family targets PUMA and p21, suggesting that PUMA, an inducer of apoptosis, and p21, an inducer of cell cycle arrest, directly regulate mammary morphogenesis. To address this, we generated multiple MCF10A cell lines in which PUMA, p21, or both were stably knocked down. We found that morphogenesis of MCF10A cells was altered modestly by knockdown of either PUMA or p21 alone but markedly by knockdown of both PUMA and p21. Moreover, we found that knockdown of PUMA and p21 leads to loss of E-cadherin expression along with increased expression of epithelial-to-mesenchymal transition (EMT) markers. Interestingly, we found that knockdown of ΔNp73, which antagonizes the ability of wide-type p53 and TA isoform of p73 to regulate PUMA and p21, mitigates the abnormal morphogenesis and EMT induced by knockdown of PUMA or p21. Together, our data suggest that PUMA cooperates with p21 to regulate normal acinus formation and EMT.
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Affiliation(s)
- Yanhong Zhang
- Comparative Oncology Laboratory, Schools of Medicine and Veterinary Medicine, University of California Davis, Davis, California, United State of America
| | - Wensheng Yan
- Comparative Oncology Laboratory, Schools of Medicine and Veterinary Medicine, University of California Davis, Davis, California, United State of America
| | - Yong Sam Jung
- Comparative Oncology Laboratory, Schools of Medicine and Veterinary Medicine, University of California Davis, Davis, California, United State of America
| | - Xinbin Chen
- Comparative Oncology Laboratory, Schools of Medicine and Veterinary Medicine, University of California Davis, Davis, California, United State of America
- * E-mail:
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17
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Zhang Y, Yan W, Chen X. P63 regulates tubular formation via epithelial-to-mesenchymal transition. Oncogene 2013; 33:1548-57. [PMID: 23542170 DOI: 10.1038/onc.2013.101] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2012] [Revised: 02/04/2013] [Accepted: 02/07/2013] [Indexed: 02/08/2023]
Abstract
P63, a p53 family member, is expressed as TA and ΔN isoforms. Interestingly, both TAp63 and ΔNp63 are transcription factors, and regulate both common and distinct sets of target genes. p63 is required for survival of some epithelial cell lineages, and lack of p63 leads to loss of epidermis and other epithelia in humans and mice. Here, we explored the role of p63 isoforms in cell proliferation, migration and tubulogenesis by using Madin-Darby Canine Kidney (MDCK) tubular epithelial cells in two- or three-dimensional (2-D or 3-D) culture. We found that like downregulation of p53, downregulation of p63 and TAp63 decreases expression of growth-suppressing genes, including p21, PUMA and MIC-1, and consequently promotes cell proliferation and migration in 2-D culture. However, in 3-D culture, downregulation of p63, especially TAp63, but not p53, decapacitates MDCK cells to form a cyst structure through enhanced epithelial-to-mesenchymal transition (EMT). In contrast, downregulation of ΔNp63 inhibits MDCK cell proliferation and migration in 2-D culture, and delays but does not block MDCK cell cyst formation and tubulogenesis in 3-D culture. Consistent with this, downregulation of ΔNp63 markedly upregulates growth-suppressing genes, including p21, PUMA and MIC-1. Taken together, these data suggest that TAp63 is the major isoform required for tubulogenesis by maintaining an appropriate level of EMT, whereas ΔNp63 fine-tunes the rate of cyst formation and tubulogenesis by maintaining an appropriate expression level of genes involved in cell cycle arrest and apoptosis.
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Affiliation(s)
- Y Zhang
- Center for Comparative Oncology, Schools of Medicine and Veterinary Medicine, University of California at Davis, Davis, CA, USA
| | - W Yan
- Center for Comparative Oncology, Schools of Medicine and Veterinary Medicine, University of California at Davis, Davis, CA, USA
| | - X Chen
- Center for Comparative Oncology, Schools of Medicine and Veterinary Medicine, University of California at Davis, Davis, CA, USA
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18
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Abstract
Intracellular membrane trafficking along endocytic and secretory transport pathways plays a critical role in diverse cellular functions including both developmental and pathological processes. Briefly, proteins and lipids destined for transport to distinct locations are collectively assembled into vesicles and delivered to their target site by vesicular fusion. SNARE (soluble N-ethylmaleimide-sensitive factor-attachment protein receptor) proteins are required for these events, during which v-SNAREs (vesicle SNAREs) interact with t-SNAREs (target SNAREs) to allow transfer of cargo from donor vesicle to target membrane. Recently, the t-SNARE family member, syntaxin-6, has been shown to play an important role in the transport of proteins that are key to diverse cellular dynamic processes. In this paper, we briefly discuss the specific role of SNAREs in various mammalian cell types and comprehensively review the various roles of the Golgi- and endosome-localized t-SNARE, syntaxin-6, in membrane trafficking during physiological as well as pathological conditions.
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19
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Perets R, Kaplan T, Stein I, Hidas G, Tayeb S, Avraham E, Ben-Neriah Y, Simon I, Pikarsky E. Genome-wide analysis of androgen receptor targets reveals COUP-TF1 as a novel player in human prostate cancer. PLoS One 2012; 7:e46467. [PMID: 23056316 PMCID: PMC3464259 DOI: 10.1371/journal.pone.0046467] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2011] [Accepted: 09/03/2012] [Indexed: 01/12/2023] Open
Abstract
Androgen activity plays a key role in prostate cancer progression. Androgen receptor (AR) is the main mediator of androgen activity in the prostate, through its ability to act as a transcription mediator. Here we performed a genome-wide analysis of human AR binding to promoters in the presence of an agonist or antagonist in an androgen dependent prostate cancer cell line. Many of the AR bound promoters are bound in all examined conditions while others are bound only in the presence of an agonist or antagonist. Several motifs are enriched in AR bound promoters, including the AR Response Element (ARE) half-site and recognition elements for the transcription factors OCT1 and SOX9. This suggests that these 3 factors could define a module of co-operating transcription factors in the prostate. Interestingly, AR bound promoters are preferentially located in AT rich genomic regions. Analysis of mRNA expression identified chicken ovalbumin upstream promoter-transcription factor 1 (COUP-TF1) as a direct AR target gene that is downregulated upon binding by the agonist liganded AR. COUP-TF1 immunostaining revealed nucleolar localization of COUP-TF1 in epithelium of human androgen dependent prostate cancer, but not in adjacent benign prostate epithelium. Stromal cells both in human and mouse prostate show nuclear COUP-TF1 staining. We further show that there is an inverse correlation between COUP-TF1 expression in prostate stromal cells and the rising levels of androgen with advancing puberty. This study extends the pool of recognized putative AR targets and identifies a negatively regulated target of AR – COUP-TF1 – which could possibly play a role in human prostate cancer.
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Affiliation(s)
- Ruth Perets
- Department of Pathology and Lautenberg center for immunology, IMRIC, The Hebrew University-Hadassah Medical School, Jerusalem, Israel
- Division of Oncology, Rambam Health Care Campus, Haifa, Israel
| | - Tommy Kaplan
- Department of Molecular and Cell Biology, California Institute of Quantitative Biosciences, University of California, Berkeley, California, United States of America
- School of Computer Science and Engineering, The Hebrew University of Jerusalem, Jerusalem, Israel
| | - Ilan Stein
- Department of Pathology and Lautenberg center for immunology, IMRIC, The Hebrew University-Hadassah Medical School, Jerusalem, Israel
| | - Guy Hidas
- Department of Pathology and Lautenberg center for immunology, IMRIC, The Hebrew University-Hadassah Medical School, Jerusalem, Israel
- Department of Urology, The Hebrew University-Hadassah Medical School, Jerusalem, Israel
| | - Shay Tayeb
- Department of Pathology and Lautenberg center for immunology, IMRIC, The Hebrew University-Hadassah Medical School, Jerusalem, Israel
| | - Eti Avraham
- Department of Pathology and Lautenberg center for immunology, IMRIC, The Hebrew University-Hadassah Medical School, Jerusalem, Israel
| | - Yinon Ben-Neriah
- Department of Pathology and Lautenberg center for immunology, IMRIC, The Hebrew University-Hadassah Medical School, Jerusalem, Israel
| | - Itamar Simon
- Department of Microbiology and Molecular Genetics, Institute for Medical Research Israel Canada (IMRIC), The Hebrew University-Hadassah Medical School, Jerusalem, Israel
| | - Eli Pikarsky
- Department of Pathology and Lautenberg center for immunology, IMRIC, The Hebrew University-Hadassah Medical School, Jerusalem, Israel
- * E-mail:
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20
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Zhang Y, Yan W, Jung YS, Chen X. Mammary epithelial cell polarity is regulated differentially by p73 isoforms via epithelial-to-mesenchymal transition. J Biol Chem 2012; 287:17746-17753. [PMID: 22457351 PMCID: PMC3366836 DOI: 10.1074/jbc.m112.358143] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2012] [Revised: 03/25/2012] [Indexed: 11/06/2022] Open
Abstract
p73 is expressed as TA and ΔN isoforms, both of which are implicated in tumor suppression and/or promotion. To address how p73 possesses these opposing functions, we developed three-dimensional culture of MCF10A cells, which undergo cell morphogenesis to form polarized spheroids with hollow lumen similar to normal mammary acini in vivo. Here, we showed that upon knockdown of p73, particularly TAp73 but not ΔNp73, MCF10A cells formed irregular and near-normal acini without hollow lumen in three-dimensional culture. We also found that upon knockdown of p73 or TAp73, but not ΔNp73, MCF10A cells underwent epithelial-to-mesenchymal transition (EMT) via down-regulation of E-cadherin coupled with up-regulation of β-catenin and laminin V. In addition, we found that Snail-1, Slug, and Twist, all of which are known to act as EMT inducers by repressing E-cadherin expression, were increased markedly upon knockdown of p73 and TAp73 but little if any by ΔNp73. Furthermore, we showed that knockdown of p73 or TAp73 in MCF10A cells led to a marked increase in cell proliferation and migration. Together, our data suggest that TAp73 is necessary for maintaining normal cell polarity by suppressing EMT.
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Affiliation(s)
- Yanhong Zhang
- Comparative Oncology Laboratory, Schools of Medicine and Veterinary Medicine, University of California, Davis, California 95616
| | - Wensheng Yan
- Comparative Oncology Laboratory, Schools of Medicine and Veterinary Medicine, University of California, Davis, California 95616
| | - Yong Sam Jung
- Comparative Oncology Laboratory, Schools of Medicine and Veterinary Medicine, University of California, Davis, California 95616
| | - Xinbin Chen
- Comparative Oncology Laboratory, Schools of Medicine and Veterinary Medicine, University of California, Davis, California 95616.
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21
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Riggs KA, Hasan N, Humphrey D, Raleigh C, Nevitt C, Corbin D, Hu C. Regulation of integrin endocytic recycling and chemotactic cell migration by syntaxin 6 and VAMP3 interaction. J Cell Sci 2012; 125:3827-39. [PMID: 22573826 DOI: 10.1242/jcs.102566] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
Abstract
Integrins are the primary receptors of cells adhering to the extracellular matrix, and play key roles in various cellular processes including migration, proliferation and survival. The expression and distribution of integrins at the cell surface is controlled by endocytosis and recycling. The present study examines the function of syntaxin 6 (STX6), a t-SNARE located in the trans-Golgi network, in integrin trafficking. STX6 is overexpressed in many types of human cancer. We show that depletion of STX6 inhibits chemotactic cell migration and the delivery of the laminin receptor α3β1 integrin to the cell surface, whereas STX6 overexpression stimulates chemotactic cell migration, integrin delivery, and integrin-initiated activation of focal adhesion kinase. These data indicate that STX6 plays a rate-limiting role in cell migration and integrin trafficking. In STX6-depleted cells, α3β1 integrin is accumulated in recycling endosomes that contain the v-SNARE VAMP3. Importantly, we show that STX6 and VAMP3 form a v-/t-SNARE complex, VAMP3 is required in α3β1 integrin delivery to the cell surface, and endocytosed α3β1 integrin traffics to both VAMP3 and STX6 compartments. Collectively, our data suggest a new integrin trafficking pathway in which endocytosed integrins are transported from VAMP3-containing recycling endosomes to STX6-containing trans-Golgi network before being recycled to the plasma membrane.
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Affiliation(s)
- Krista A Riggs
- Department of Biochemistry and Molecular Biology, University of Louisville School of Medicine, Louisville, KY 40202, USA
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22
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Shen DW, Gottesman MM. RAB8 enhances TMEM205-mediated cisplatin resistance. Pharm Res 2012; 29:643-50. [PMID: 21969054 PMCID: PMC3288766 DOI: 10.1007/s11095-011-0562-y] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2011] [Accepted: 08/03/2011] [Indexed: 01/13/2023]
Abstract
PURPOSE To determine whether the small endosomal recycling GTPase, RAB8, plays a role in TMEM205-associated resistance to the chemotherapeutic drug cisplatin. METHODS Antibodies were used as markers for both genes; confocal microscopy was used to visualize their localization in cisplatin-resistant cells. Both single and dual-transfections were performed. RESULTS Expression of RAB8 was markedly elevated in human cisplatin-resistant cells. We found that TMEM205 was co-localized with RAB8. Dual transfectants with over-expression of both TMEM205 and RAB8 were found to be up to 4-fold more resistant to cisplatin, while cells transfected with RAB8 alone were ~2-fold more resistant. CONCLUSIONS The development of cisplatin resistance appears to be a consequence of pleotropic epigenetic alterations. We unravel the role of one gene, the GTPase RAB8, in this process. Because its highest expression was at an early step of cisplatin resistance, it may be involved in early development of resistance. Increased expression of TMEM205 and RAB8 in double-transfected cells and their increased resistance to cisplatin indicate an additive effect of these two genes, mediating cisplatin resistance. These two proteins are potential biomarkers or targets for gene or chemotherapy.
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Affiliation(s)
- Ding-Wu Shen
- Laboratory of Cell Biology, Center for Cancer Research National Cancer Institute, National Institutes of Health, 37 Convent Drive, Room 2108, Bethesda, Maryland, 20892-4254, USA
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23
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Naydenov NG, Harris G, Brown B, Schaefer KL, Das SK, Fisher PB, Ivanov AI. Loss of soluble N-ethylmaleimide-sensitive factor attachment protein α (αSNAP) induces epithelial cell apoptosis via down-regulation of Bcl-2 expression and disruption of the Golgi. J Biol Chem 2011; 287:5928-41. [PMID: 22194596 DOI: 10.1074/jbc.m111.278358] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Intracellular trafficking represents a key mechanism that regulates cell fate by participating in either prodeath or prosurvival signaling. Soluble N-ethylmaleimide-sensitive factor (NSF) attachment protein α (αSNAP) is a well known component of vesicle trafficking machinery that mediates intermembrane fusion. αSNAP increases cell resistance to cytotoxic stimuli, although mechanisms of its prosurvival function are poorly understood. In this study, we found that either siRNA-mediated knockdown of αSNAP or expression of its dominant negative mutant induced epithelial cell apoptosis. Apoptosis was not caused by activation of the major prodeath regulators Bax and p53 and was independent of a key αSNAP binding partner, NSF. Instead, death of αSNAP-depleted cells was accompanied by down-regulation of the antiapoptotic Bcl-2 protein; it was mimicked by inhibition and attenuated by overexpression of Bcl-2. Knockdown of αSNAP resulted in impairment of Golgi to endoplasmic reticulum (ER) trafficking and fragmentation of the Golgi. Moreover, pharmacological disruption of ER-Golgi transport by brefeldin A and eeyarestatin 1 or siRNA-mediated depletion of an ER/Golgi-associated p97 ATPase recapitulated the effects of αSNAP inhibition by decreasing Bcl-2 level and triggering apoptosis. These results reveal a novel role for αSNAP in promoting epithelial cell survival by unique mechanisms involving regulation of Bcl-2 expression and Golgi biogenesis.
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Affiliation(s)
- Nayden G Naydenov
- Department of Medicine, University of Rochester, Rochester, New York 14642, USA
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24
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Tiwari A, Jung JJ, Inamdar SM, Brown CO, Goel A, Choudhury A. Endothelial cell migration on fibronectin is regulated by syntaxin 6-mediated alpha5beta1 integrin recycling. J Biol Chem 2011; 286:36749-61. [PMID: 21880737 DOI: 10.1074/jbc.m111.260828] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
The α5β1 integrin heterodimer regulates many processes that contribute to embryonic development and angiogenesis, in both physiological and pathological contexts. As one of the major adhesion complexes on endothelial cells, it plays a vital role in adhesion and migration along the extracellular matrix. We recently showed that angiogenesis is modulated by syntaxin 6, a Golgi- and endosome-localized t-SNARE, and that it does so by regulating the post-Golgi trafficking of VEGFR2. Here we show that syntaxin 6 is also required for α5β1 integrin-mediated adhesion of endothelial cells to, and migration along, fibronectin. We demonstrate that syntaxin 6 and α5β1 integrin colocalize in EEA1-containing early endosomes, and that functional inhibition of syntaxin 6 leads to misrouting of β1 integrin to the degradation pathway (late endosomes and lysosomes) rather transport along recycling pathway from early endosomes; an increase in the pool of ubiquitinylated α5 integrin and its lysosome-dependent degradation; reduced cell spreading on fibronectin; decreased Rac1 activation; and altered Rac1 localization. Collectively, our data show that functional syntaxin 6 is required for the regulation of α5β1-mediated endothelial cell movement on fibronectin. These syntaxin 6-regulated membrane trafficking events control outside-in signaling via haptotactic and chemotactic mechanisms.
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Affiliation(s)
- Ajit Tiwari
- Department of Anatomy and Cell Biology, University of Iowa, Iowa City, Iowa 52242, USA
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25
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Palmieri M, Impey S, Kang H, di Ronza A, Pelz C, Sardiello M, Ballabio A. Characterization of the CLEAR network reveals an integrated control of cellular clearance pathways. Hum Mol Genet 2011; 20:3852-66. [PMID: 21752829 DOI: 10.1093/hmg/ddr306] [Citation(s) in RCA: 681] [Impact Index Per Article: 52.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
In metazoans, lysosomes are the center for the degradation of macromolecules and play a key role in a variety of cellular processes, such as autophagy, exocytosis and membrane repair. Defects of lysosomal pathways are associated with lysosomal storage disorders and with several late onset neurodegenerative diseases. We recently discovered the CLEAR (Coordinated Lysosomal Expression and Regulation) gene network and its master gene transcription factor EB (TFEB), which regulates lysosomal biogenesis and function. Here, we used a combination of genomic approaches, including ChIP-seq (sequencing of chromatin immunoprecipitate) analysis, profiling of TFEB-mediated transcriptional induction, genome-wide mapping of TFEB target sites and recursive expression meta-analysis of TFEB targets, to identify 471 TFEB direct targets that represent essential components of the CLEAR network. This analysis revealed a comprehensive system regulating the expression, import and activity of lysosomal enzymes that control the degradation of proteins, glycosaminoglycans, sphingolipids and glycogen. Interestingly, the CLEAR network appears to be involved in the regulation of additional lysosome-associated processes, including autophagy, exo- and endocytosis, phagocytosis and immune response. Furthermore, non-lysosomal enzymes involved in the degradation of essential proteins such as hemoglobin and chitin are also part of the CLEAR network. Finally, we identified nine novel lysosomal proteins by using the CLEAR network as a tool for prioritizing candidates. This study provides potential therapeutic targets to modulate cellular clearance in a variety of disease conditions.
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Affiliation(s)
- Michela Palmieri
- Department of Molecular and Human Genetics, Baylor College of Medicine, Jan and Dan Duncan Neurological Research Institute at Texas Children's Hospital, Houston, TX, USA
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26
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Integrated biochemical and computational approach identifies BCL6 direct target genes controlling multiple pathways in normal germinal center B cells. Blood 2009; 115:975-84. [PMID: 19965633 DOI: 10.1182/blood-2009-06-227017] [Citation(s) in RCA: 168] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
BCL6 is a transcriptional repressor required for mature B-cell germinal center (GC) formation and implicated in lymphomagenesis. BCL6's physiologic function is only partially known because the complete set of its targets in GC B cells has not been identified. To address this issue, we used an integrated biochemical-computational-functional approach to identify BCL6 direct targets in normal GC B cells. This approach includes (1) identification of BCL6-bound promoters by genome-wide chromatin immunoprecipitation, (2) inference of transcriptional relationships by the use of a regulatory network reverse engineering approach (ARACNe), and (3) validation of physiologic relevance of the candidate targets down-regulated in GC B cells. Our approach demonstrated that a large set of promoters (> 4000) is physically bound by BCL6 but that only a fraction of them is repressed in GC B cells. This set of 1207 targets identifies several cellular functions directly controlled by BCL6 during GC development, including activation, survival, DNA-damage response, cell cycle arrest, cytokine signaling, Toll-like receptor signaling, and differentiation. These results define a broad role of BCL6 in preventing centroblasts from responding to signals leading to exit from the GC before they complete the phase of proliferative expansion and of antibody affinity maturation.
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27
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Rajcan-Separovic E, Qiao Y, Tyson C, Harvard C, Fawcett C, Kalousek D, Stephenson M, Philipp T. Genomic changes detected by array CGH in human embryos with developmental defects. Mol Hum Reprod 2009; 16:125-34. [PMID: 19778950 DOI: 10.1093/molehr/gap083] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Developmental abnormalities of human embryos can be visualized in utero using embryoscopy. Our previous embryoscopic and genetic evaluations detected developmental abnormalities in the majority of both euploid (74%) and aneuploid or polyploid (90%) miscarriages. Since we found the pattern of morphological changes to be similar in euploid and non-euploid embryos, we proposed that lethal submicroscopic changes, not detected by standard chromosome testing, may be responsible for miscarriage of euploid embryos. Whole genome oligo and bacterial artificial chromosome array comparative genome hybridization (CGH) was used to screen for submicroscopic chromosomal changes (DNA copy number variants or CNVs) in 17 euploid embryonic miscarriages, with a range of developmental abnormalities documented by embryoscopy. The CNV breakpoints were refined using a custom array (Agilent) with high resolution coverage of the CNVs. Six unique CNVs, previously not reported, were identified in 5 of the 17 embryos (29% of all cases or 50% of cases studied with higher resolution arrays). All six unique CNVs were <250 kb in size. On the basis of parental array CGH analysis, a de novo origin of a CNV was determined for one embryo (at 13q32.1) and suspected for another (at 10p15.3). Three CNVs, at Xq28, 1q25.3 and 7p14.3, were inherited and a CNV at 17p13.1 was of unknown origin. The genes contained within these unique CNVs will be discussed, with specific reference to rearrangements of syntaxin and tryptophan-aspartic acid (WD) repeat genes. Our report describes for the first time, de novo and inherited unique CNVs in euploid human embryos with specific developmental defects.
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Affiliation(s)
- E Rajcan-Separovic
- Department of Pathology and Laboratory Medicine, University of British Columbia (UBC), Vancouver, BC, Canada, V5Z 4H4.
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28
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Zhang Y, Qian Y, Lu W, Chen X. The G protein-coupled receptor 87 is necessary for p53-dependent cell survival in response to genotoxic stress. Cancer Res 2009; 69:6049-56. [PMID: 19602589 DOI: 10.1158/0008-5472.can-09-0621] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
p53 regulates an array of target genes, which mediates p53 tumor suppression by inducing cell cycle arrest, apoptosis, and cell survival. G protein-coupled receptors belong to a superfamily of cell surface molecules and are known to regulate cell proliferation, migration, and survival. Here, we found that G protein-coupled receptor 87 (GPR87) was up-regulated by p53 and by DNA damage in a p53-dependent manner. We also found that p53 directly regulated GPR87 potentially via a p53-responsive element in the GPR87 gene. To investigate the role of GPR87 in the p53 pathway, we generated multiple RKO and MCF7 cell lines in that GPR87 can be inducibly overexpressed or knocked down by a tetracycline-inducible system. We found that overexpression of GPR87 had little effect on cell growth. However, GPR87 knockdown sensitized cancer cells to DNA damage-induced growth suppression via enhanced p53 stabilization and activation. Importantly, the prosurvival activity of GPR87 can be reversed by knockdown of p53. Together, our results suggested that GPR87 is essential for p53-dependent cell survival in response to DNA damage. Thus, due to its expression on the cell surface and its role in cell survival, GPR87 may be explored as a novel therapeutic target for cancer treatment and prevention.
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Affiliation(s)
- Yanhong Zhang
- Center for Comparative Oncology, Schools of Medicine and Veterinary Medicine, University of California, Davis, California 95616, USA
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