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Soundararajan A, Wang T, Ghag SA, Kang MH, Pattabiraman PP. Novel insight into the role of clusterin on intraocular pressure regulation by modifying actin polymerization and extracellular matrix remodeling in the trabecular meshwork. J Cell Physiol 2022; 237:3012-3029. [PMID: 35567755 PMCID: PMC9283260 DOI: 10.1002/jcp.30769] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/25/2021] [Revised: 04/03/2022] [Accepted: 04/20/2022] [Indexed: 11/09/2022]
Abstract
This study provides comprehensive mechanistic evidence for the role of clusterin, a stress-response secretory chaperone protein, in the modulation of intraocular pressure (IOP) by regulating the trabecular meshwork (TM) actin cytoskeleton and the extracellular matrix (ECM). The pathological stressors on TM known to elevate IOP significantly lowered clusterin protein levels indicating stress-related clusterin function loss. Small interfering RNA-mediated clusterin loss in human TM cells in vitro induced actin polymerization and stabilization via protein kinase D1, serine/threonine-protein kinase N2 (PRK2), and LIM kinase 1 (LIMK1), and the recruitment and activation of adhesome proteins including paxillin, vinculin, and integrin αV and β5. A complete loss of clusterin as seen in clusterin knockout mice (Clu-/- ) led to significant IOP elevation at postnatal Day 70. Contrarily, constitutive clusterin expression using adenovirus (AdCLU) in HTM cells resulted in the loss of actin polymerization via decreased PRK2, and LIMK1 and negative regulation of integrin αV and β5. Furthermore, we found that AdCLU treatment in HTM cells significantly decreased the ECM protein expression and distribution by significantly increasing matrix metalloprotease 2 (MMP2) activity and lowering the levels of pro-fibrotic proteins such as transforming growth factor-β2 (TGFβ2), thrombospondin-1 (TSP-1), and plasminogen activator inhibitor-1 (PAI-1). Finally, we found that HTM cells supplemented with recombinant human clusterin attenuated the pro-fibrotic effects of TGFβ2. For the first time this study demonstrates the importance of clusterin in the regulation of TM actin cytoskeleton - ECM interactions and the maintenance of IOP, thus making clusterin an interesting target to reverse elevated IOP.
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Affiliation(s)
- Avinash Soundararajan
- Department of Ophthalmology, Glick Eye InstituteIndiana University School of MedicineIndianapolisIndianaUSA
| | - Ting Wang
- Department of Ophthalmology, Glick Eye InstituteIndiana University School of MedicineIndianapolisIndianaUSA
- Stark Neuroscience Research InstituteIndiana University Purdue University IndianapolisIndianapolisIndianaUSA
| | - Sachin A. Ghag
- Department of Ophthalmology, Glick Eye InstituteIndiana University School of MedicineIndianapolisIndianaUSA
| | - Min H. Kang
- Department of Ophthalmology and Visual Sciences, University Hospitals Eye InstituteCase Western Reserve University School of MedicineClevelandOhioUSA
| | - Padmanabhan P. Pattabiraman
- Department of Ophthalmology, Glick Eye InstituteIndiana University School of MedicineIndianapolisIndianaUSA
- Stark Neuroscience Research InstituteIndiana University Purdue University IndianapolisIndianapolisIndianaUSA
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2
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Wilson MR, Satapathy S, Jeong S, Fini ME. Clusterin, other extracellular chaperones, and eye disease. Prog Retin Eye Res 2021; 89:101032. [PMID: 34896599 DOI: 10.1016/j.preteyeres.2021.101032] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2021] [Revised: 11/30/2021] [Accepted: 11/30/2021] [Indexed: 12/15/2022]
Abstract
Proteostasis refers to all the processes that maintain the correct expression level, location, folding and turnover of proteins, essential to organismal survival. Both inside cells and in body fluids, molecular chaperones play key roles in maintaining proteostasis. In this article, we focus on clusterin, the first-recognized extracellular mammalian chaperone, and its role in diseases of the eye. Clusterin binds to and inhibits the aggregation of proteins that are misfolded due to mutations or stresses, clears these aggregating proteins from extracellular spaces, and facilitates their degradation. Clusterin exhibits three main homeostatic activities: proteostasis, cytoprotection, and anti-inflammation. The so-called "protein misfolding diseases" are caused by aggregation of misfolded proteins that accumulate pathologically as deposits in tissues; we discuss several such diseases that occur in the eye. Clusterin is typically found in these deposits, which is interpreted to mean that its capacity as a molecular chaperone to maintain proteostasis is overwhelmed in the disease state. Nevertheless, the role of clusterin in diseases involving such deposits needs to be better defined before therapeutic approaches can be entertained. A more straightforward case can be made for therapeutic use of clusterin based on its proteostatic role as a proteinase inhibitor, as well as its cytoprotective and anti-inflammatory properties. It is likely that clusterin works together in this way with other extracellular chaperones to protect the eye from disease, and we discuss several examples. We end this article by predicting future steps that may lead to development of clusterin as a biological drug.
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Affiliation(s)
- Mark R Wilson
- Molecular Horizons and the School of Chemistry and Molecular Bioscience, University of Wollongong; Illawarra Health and Medical Research Institute, Northfields Avenue, Wollongong, New South Wales, 2522, Australia.
| | - Sandeep Satapathy
- Molecular Horizons and the School of Chemistry and Molecular Bioscience, University of Wollongong; Illawarra Health and Medical Research Institute, Northfields Avenue, Wollongong, New South Wales, 2522, Australia.
| | - Shinwu Jeong
- USC Roski Eye Institute and Department of Ophthalmology, Keck School of Medicine of USC, University of Southern California, 1333 San Pablo Street., Los Angeles, CA, 90033, USA.
| | - M Elizabeth Fini
- New England Eye Center, Tufts Medical Center and Department of Ophthalmology, Tufts University School of Medicine; Program in Pharmacology & Drug Development, Graduate School of Biomedical Sciences, Tufts University, 800 Washington St, Boston, MA, 02111, USA.
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Yao M, Sai W, Zheng W, Wang L, Dong Z, Yao D. Secretory Clusterin as a Novel Molecular-targeted Therapy for Inhibiting Hepatocellular Carcinoma Growth. Curr Med Chem 2020; 27:3290-3301. [PMID: 31232234 DOI: 10.2174/0929867326666190624161158] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2018] [Revised: 03/19/2019] [Accepted: 05/28/2019] [Indexed: 02/08/2023]
Abstract
BACKGROUND Although secretory clusterin (sCLU) plays a crucial role in Hepatocellular Carcinoma (HCC) cells proliferation, Multiple Drug Resistance (MDR), metastasis and so on, its targeted effects and exact mechanism are still unknown. This review summarizes some new progress in sCLU as a molecular-targeted therapy in the treatment of HCC. METHODS A systematic review of the published English-language literature about sCLU and HCC has been performed using the PubMed and bibliographic databases. Some valuable studies on sCLU in HCC progression were searched for relevant articles with the keywords: HCC, diagnosis, MDR, as molecular-targeted in treatment, and so on. RESULTS The incidence of the positive rate of sCLU was significantly higher in HCC tissues as compared to the surrounding tissues at mRNA or protein level, gradually increasing with tumor-nodemetastasis staging (P<0.05). Also, the abnormal level of sCLU was related to poor differentiation degree, and considered as a useful marker for HCC diagnosis or independent prognosis for patients. Hepatic sCLU could be silenced at mRNA level by specific sCLU-shRNA or by OGX-011 to inhibit cancer cell proliferation with an increase in apoptosis, cell cycle arrest, reversal MDR, alteration of cell migration or invasion behaviors, and a decrease in GSK-3β or AKT phosphorylation in vitro, as well as significant suppression of the xenograft growth by down-regulating β-catenin, p-GSK3β, and cyclinD1 expression in vivo. CONCLUSION Abnormal hepatic sCLU expression should not only be a new diagnostic biomarker but also a novel promising target for inhibiting HCC growth.
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Affiliation(s)
- Min Yao
- Medical School of Nantong University, Affiliated Hospital of Nantong University, Nantong 226001, Jiangsu Province, China.,Research Center of Clinical Medicine, Affiliated Hospital of Nantong University, Nantong 226001, Jiangsu Province, China
| | - Wenli Sai
- Research Center of Clinical Medicine, Affiliated Hospital of Nantong University, Nantong 226001, Jiangsu Province, China
| | - Wenjie Zheng
- Research Center of Clinical Medicine, Affiliated Hospital of Nantong University, Nantong 226001, Jiangsu Province, China
| | - Li Wang
- Medical School of Nantong University, Affiliated Hospital of Nantong University, Nantong 226001, Jiangsu Province, China
| | - Zhizhen Dong
- Department of Diagnostics, Affiliated Hospital of Nantong University, Nantong 226001, Jiangsu Province, China
| | - Dengfu Yao
- Medical School of Nantong University, Affiliated Hospital of Nantong University, Nantong 226001, Jiangsu Province, China.,Research Center of Clinical Medicine, Affiliated Hospital of Nantong University, Nantong 226001, Jiangsu Province, China
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Zheng W, Yao M, Wu M, Yang J, Yao D, Wang L. Secretory clusterin promotes hepatocellular carcinoma progression by facilitating cancer stem cell properties via AKT/GSK-3β/β-catenin axis. J Transl Med 2020; 18:81. [PMID: 32059741 PMCID: PMC7023808 DOI: 10.1186/s12967-020-02262-7] [Citation(s) in RCA: 36] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2019] [Accepted: 02/10/2020] [Indexed: 01/10/2023] Open
Abstract
Background To explore the modulatory effects and mechanism of secretory clusterin (sCLU) on cancer stem cell (CSC) properties in hepatocellular carcinoma (HCC). Methods The effects of sCLU repression or overexpression on chemoresistance, migration, invasion, and tumor growth were detected by MTT, wound healing, transwell assays, and xenograft assay, respectively. The tumor sphere assay was performed to evaluate the self-renewal ability of HCC cells. In addition, the molecular regulation between sCLU and AKT/GSK-3β/β-catenin axis in HCC cells were discovered by western blotting, quantitative real-time PCR (qRT-PCR), and immunofluorescence. The expression status of sCLU and β-catenin in HCC tissues were investigated by immunohistochemistry. Results Knockdown or overexpressing sCLU remarkably inhibited or promoted the chemoresistance against sorafenib/doxorubicin, metastasis, and tumor growth of HCC cells, respectively. HepG2 and HCCLM3-derived spheroids showed higher expression of sCLU than that in attached cells. Additionally, repressing sCLU impaired the self-renewal capacity of HCC cells and CSC-related chemoresistance while overexpression of sCLU enhanced these CSC properties. Knockdown or overexpression of sCLU inhibited or increased the expressions of β-catenin, cyclinD1, MMP-2 and MMP-9, and the phosphorylation of AKT or GSK3β signaling, respectively. However, LiCl or LY294002 abrogated the effects mediated by sCLU silencing or overexpression on chemoresistance, metastasis, and CSC phenotype. Furthermore, co-expression of sCLU and β-catenin in HCC tissues indicated poor prognosis of HCC patients. Conclusions Taken together, the oncogenic sCLU might promote CSC phenotype via activating AKT/GSK3β/β-catenin axis, suggesting that sCLU was a potential molecular-target for HCC therapy.
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Affiliation(s)
- Wenjie Zheng
- Research Center of Clinical Medicine, Affiliated Hospital of Nantong University, 20 Xisi Road, Nantong, 226001, Jiangsu, China.,Medical School of Nantong University, 19 Qixiu Road, Nantong, 226001, Jiangsu, China
| | - Min Yao
- Medical School of Nantong University, 19 Qixiu Road, Nantong, 226001, Jiangsu, China
| | - Mengna Wu
- Research Center of Clinical Medicine, Affiliated Hospital of Nantong University, 20 Xisi Road, Nantong, 226001, Jiangsu, China
| | - Junling Yang
- Research Center of Clinical Medicine, Affiliated Hospital of Nantong University, 20 Xisi Road, Nantong, 226001, Jiangsu, China
| | - Dengfu Yao
- Research Center of Clinical Medicine, Affiliated Hospital of Nantong University, 20 Xisi Road, Nantong, 226001, Jiangsu, China.
| | - Li Wang
- Medical School of Nantong University, 19 Qixiu Road, Nantong, 226001, Jiangsu, China.
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Host Cell Proteases: Cathepsins. ACTIVATION OF VIRUSES BY HOST PROTEASES 2018. [PMCID: PMC7123490 DOI: 10.1007/978-3-319-75474-1_10] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Cathepsins are proteolytic enzymes with a broad spectrum of substrates. They are known to reside within endo-lysosomes where they acquire optimal conditions for proteolytic activity and substrate cleavage. However, cathepsins have been detected in locations other than the canonical compartments of the endocytotic pathway. They are often secreted from cells in either proteolytically inactive proform or as mature and active enzyme; this may happen in both physiological and pathological conditions. Moreover, cytosolic and nuclear forms of cathepsins have been described and are currently an emerging field of research aiming at understanding their functions in such unexpected cellular locations. This chapter summarizes the canonical pathways of biosynthesis and transport of cathepsins in healthy cells. We further describe how cathepsins can reach unexpected locations such as the extracellular space or the cytosol and the nuclear matrix. No matter where viruses and cathepsins encounter, several outcomes can be perceived. Thus, scenarios are discussed on how cathepsins may support virus entry into host cells, involve in viral fusion factor and polyprotein processing in different host cell compartments, or help in packaging of viral particles during maturation. It is of note to mention that this review is not meant to comprehensively cover the present literature on viruses encountering cathepsins but rather illustrates, on some representative examples, the possible roles of cathepsins in replication of viruses and in the course of disease.
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Zheng W, Yao M, Qian Q, Sai W, Qiu L, Yang J, Wu W, Dong Z, Yao D. Oncogenic secretory clusterin in hepatocellular carcinoma: Expression at early staging and emerging molecular target. Oncotarget 2016; 8:52321-52332. [PMID: 28881732 PMCID: PMC5581031 DOI: 10.18632/oncotarget.13674] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2016] [Accepted: 11/18/2016] [Indexed: 02/06/2023] Open
Abstract
Secretory clusterin (sCLU) is associated with hepatocellular carcinoma (HCC) progression by contributing to angiogenesis, chemoresistance, cell survival, and metastasis. However, the sCLU expression at early stage of HCC progression remains to be clarified. In this study, the alteration of sCLU oncogenicity was firstly evaluated in HCC- and their para-cancerous- tissues. The incidence of sCLU expression in HCC was significantly higher than that in their non-tumorous tissues at message RNA (mRNA) or protein level, gradually increasing with tumor-node-metastasis (TNM) staging. Abnormal sCLU expression was associated with the poor differentiation, TNM stage, and considered as an independent prognostic factor for HCC patients. Furthermore, silencing sCLU gene transcription inhibited the colony formation and proliferation of HCC cells, with decreasing phosphorylation level of AKT and GSK-3β in HCCLM3 cells in vitro and significantly suppressed the HCC xenograft growth in vivo, suggesting that sCLU with oncogenicity should be not only an early indicator but also novel potential molecular-targeted therapy for HCC.
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Affiliation(s)
- Wenjie Zheng
- Research Center of Clinical Medicine, Affiliated Hospital of Nantong University, Nantong 226001, Jiangsu Province, China
| | - Min Yao
- Department of Immunology, Medical School of Nantong University, Nantong 226001, Jiangsu Province, China
| | - Qi Qian
- Department of Oncology, Yancheng 1 People's Hospital, Yancheng 224005, Jiangsu Province, China
| | - Wenli Sai
- Research Center of Clinical Medicine, Affiliated Hospital of Nantong University, Nantong 226001, Jiangsu Province, China
| | - Liwei Qiu
- Research Center of Clinical Medicine, Affiliated Hospital of Nantong University, Nantong 226001, Jiangsu Province, China
| | - Junling Yang
- Research Center of Clinical Medicine, Affiliated Hospital of Nantong University, Nantong 226001, Jiangsu Province, China
| | - Wei Wu
- Research Center of Clinical Medicine, Affiliated Hospital of Nantong University, Nantong 226001, Jiangsu Province, China
| | - Zhizhen Dong
- Research Center of Clinical Medicine, Affiliated Hospital of Nantong University, Nantong 226001, Jiangsu Province, China.,Department of Diagnostics, Affiliated Hospital of Nantong University, Nantong 226001, Jiangsu Province, China
| | - Dengfu Yao
- Research Center of Clinical Medicine, Affiliated Hospital of Nantong University, Nantong 226001, Jiangsu Province, China
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Zheng W, Yao M, Sai W, Qian Q, Pan L, Qiu L, Huang J, Wu W, Yao D. Diagnostic and prognostic significance of secretory clusterin expression in patients with hepatocellular carcinoma. Tumour Biol 2015; 37:999-1008. [PMID: 26264614 DOI: 10.1007/s13277-015-3875-3] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2015] [Accepted: 07/30/2015] [Indexed: 12/14/2022] Open
Abstract
The upregulation of secretory clusterin (sCLU) is associated with tumor progression by contributing to angiogenesis, chemo-resistance, cell survival, and metastasis. However, its diagnostic or prognostic values for hepatocellular carcinoma (HCC) still remain to be clarified. The average serum sCLU level analyzed by an enzyme-linked immunosorbent assay was significantly higher (P < 0.001) in HCC patients than that in any of cases with cirrhosis, chronic hepatitis, or healthy control. The area under receiver operating characteristic curve and diagnostic sensitivity were 0.75 and 74.7 % in sCLU, and 0.74 and 58.7 % in α-fetoprotein (AFP), respectively. The combining detections of sCLU and AFP rose up to 90.7 % for HCC diagnosis. In liver, sCLU by immunohistochemistry was significantly higher (P < 0.001) in the HCC (77.3 %) group than that in their para-cancerous group (33.3 %). Abnormal serum or tissue sCLU expression was closely associated with tumor-node-metastasis (TNM) classification of malignant tumors and lymph node metastasis, as an independent prognosis factor (hazard ratio, 2.287; 95 % confidence interval, 1.044-5.007; P = 0.039), and higher sCLU expression significantly correlated (χ (2) = 4.252, P = 0.039) with poor survival of HCC patients analyzed by multivariate Cox regression or Kaplan-Meier method, suggesting that abnormal sCLU expression associated with tumor progression could be a potential diagnostic and prognostic biomarker for HCC.
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Affiliation(s)
- Wenjie Zheng
- Research Center of Clinical Medicine, Affiliated Hospital of Nantong University, 20 West Temple Road, Nantong, 226001, Jiangsu, China
| | - Min Yao
- Department of Immunology, Medical School of Nantong University, Nantong, 226001, Jiangsu, China
| | - Wenli Sai
- Research Center of Clinical Medicine, Affiliated Hospital of Nantong University, 20 West Temple Road, Nantong, 226001, Jiangsu, China
| | - Qi Qian
- Department of Oncology, Affiliated Hospital of Nantong University, Nantong, 226001, Jiangsu, China
| | - Liuhong Pan
- Department of Oncology, Affiliated Hospital of Nantong University, Nantong, 226001, Jiangsu, China
| | - Liwei Qiu
- Research Center of Clinical Medicine, Affiliated Hospital of Nantong University, 20 West Temple Road, Nantong, 226001, Jiangsu, China
| | - Jianfei Huang
- Department of Pathology, Affiliated Hospital of Nantong University, Nantong, 226001, Jiangsu, China
| | - Wei Wu
- Research Center of Clinical Medicine, Affiliated Hospital of Nantong University, 20 West Temple Road, Nantong, 226001, Jiangsu, China
| | - Dengfu Yao
- Research Center of Clinical Medicine, Affiliated Hospital of Nantong University, 20 West Temple Road, Nantong, 226001, Jiangsu, China.
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Zheng W, Sai W, Yao M, Gu H, Yao Y, Qian Q, Yao D. Silencing clusterin gene transcription on effects of multidrug resistance reversing of human hepatoma HepG2/ADM cells. Tumour Biol 2015; 36:3995-4003. [DOI: 10.1007/s13277-015-3043-9] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2014] [Accepted: 01/02/2015] [Indexed: 12/27/2022] Open
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Zheng W, Sai W, Yao M, Gu H, Yao Y, Qian Q, Yao D. Silencing clusterin gene transcription on effects of multidrug resistance reversing of human hepatoma HepG2/ADM cells. Tumour Biol 2015. [PMID: 25600802 DOI: 10.1007/s13277-015] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Abnormal clusterin (CLU) expression is associated with multidrug resistance (MDR) of hepatocellular carcinoma (HCC). In the present study, the CLU expression was analyzed in human hepatoma cells and chemoresistant counterpart HepG2/ADM cells. Compared with L02 cells, the overexpression of cellular CLU was identified in HepG2, HepG2/ADM, SMMC7721, Hep3B ,and PLC cells and relatively lower expression in Bel-7404, SNU-739, and MHCC97H cells. Specific short hairpin RNAs (shRNAs) to silence CLU gene transcription were designed, and the most effective sequences were screened. After the HepG2/ADM cells transfected with shRNA-1, the inhibition of CLU expression was 73.68 % at messenger RNA (mRNA) level by real-time quantitative RT-PCR with obvious enhancement in cell chemosensitivity, increasing apoptosis induced by doxorubicin using fluorescence kit, and Rh-123 retention qualified with flow cytometry. Knockdown CLU also significantly decreased the drug efflux pump activity through the depression of MDR1/P-glycoprotein (q = 11.739, P < 0.001). Moreover, silencing CLU led to downregulation of β-catenin (q = 13.544, P = 0.001), suggesting that downregulation of CLU might be a key point to reverse multidrug resistance of HepG2/ADM cells.
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Affiliation(s)
- Wenjie Zheng
- Research Center of Clinical Medicine, Affiliated Hospital of Nantong University, 20 West Temple Road, Nantong, 226001, Jiangsu Province, China
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Novinec M, Lenarčič B, Baici A. Probing the activity modification space of the cysteine peptidase cathepsin K with novel allosteric modifiers. PLoS One 2014; 9:e106642. [PMID: 25184245 PMCID: PMC4153677 DOI: 10.1371/journal.pone.0106642] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2014] [Accepted: 08/07/2014] [Indexed: 01/08/2023] Open
Abstract
Targeting allosteric sites is gaining increasing recognition as a strategy for modulating the activity of enzymes, especially in drug design. Here we investigate the mechanisms of allosteric regulation of cathepsin K as a representative of cysteine cathepsins and a promising drug target for the treatment of osteoporosis. Eight novel modifiers are identified by computational targeting of predicted allosteric sites on the surface of the enzyme. All act via hyperbolic kinetic mechanisms in presence of low molecular mass substrates, as expected for allosteric effectors. Two compounds have sizable effects on enzyme activity using interstitial collagen as a natural substrate of cathepsin K and four compounds show a significantly stabilizing effect on cathepsin K. The concept of activity modification space is introduced to obtain a global perspective of the effects elicited by the modifiers. Analysis of the activity modification space reveals that the activity of cathepsin K is regulated via multiple, different allosteric mechanisms.
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Affiliation(s)
- Marko Novinec
- Department of Chemistry and Biochemistry, Faculty of Chemistry and Chemical Technology, University of Ljubljana, Ljubljana, Slovenia
- Department of Biochemistry, University of Zürich, Zürich, Switzerland
- * E-mail: (MN); (AB)
| | - Brigita Lenarčič
- Department of Chemistry and Biochemistry, Faculty of Chemistry and Chemical Technology, University of Ljubljana, Ljubljana, Slovenia
- Department of Biochemistry and Molecular and Structural Biology, Jožef Stefan Institute, Ljubljana, Slovenia
| | - Antonio Baici
- Department of Biochemistry, University of Zürich, Zürich, Switzerland
- * E-mail: (MN); (AB)
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