1
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Albraiki S, Ajiboye O, Sargent R, Beck MR. Functional comparison of full-length palladin to isolated actin binding domain. Protein Sci 2023; 32:e4638. [PMID: 37027210 PMCID: PMC10117391 DOI: 10.1002/pro.4638] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2022] [Revised: 03/29/2023] [Accepted: 04/04/2023] [Indexed: 04/08/2023]
Abstract
Palladin is an actin binding protein that is specifically upregulated in metastatic cancer cells but also colocalizes with actin stress fibers in normal cells and is critical for embryonic development as well as wound healing. Of nine isoforms present in humans, only the 90 kDa isoform of palladin, comprising three immunoglobulin (Ig) domains and one proline-rich region, is ubiquitously expressed. Previous work has established that the Ig3 domain of palladin is the minimal binding site for F-actin. In this work, we compare functions of the 90 kDa isoform of palladin to the isolated actin binding domain. To understand the mechanism of action for how palladin can influence actin assembly, we monitored F-actin binding and bundling as well as actin polymerization, depolymerization, and copolymerization. Together, these results demonstrate that there are key differences between the Ig3 domain and full-length palladin in actin binding stoichiometry, polymerization, and interactions with G-actin. Understanding the role of palladin in regulating the actin cytoskeleton may help us develop means to prevent cancer cells from reaching the metastatic stage of cancer progression.
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Affiliation(s)
- Sharifah Albraiki
- Department of Chemistry and BiochemistryWichita State UniversityWichitaKansasUSA
- Department of Chemistry and GeosciencesJacksonville State UniversityJacksonvilleAlabamaUSA
| | - Oluwatosin Ajiboye
- Department of Chemistry and BiochemistryWichita State UniversityWichitaKansasUSA
| | - Rachel Sargent
- Department of Chemistry and BiochemistryWichita State UniversityWichitaKansasUSA
| | - Moriah R. Beck
- Department of Chemistry and BiochemistryWichita State UniversityWichitaKansasUSA
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2
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Dias C, Nita E, Faktor J, Tynan AC, Hernychova L, Vojtesek B, Nylandsted J, Hupp TR, Kunath T, Ball KL. CHIP-dependent regulation of the actin cytoskeleton is linked to neuronal cell membrane integrity. iScience 2021; 24:102878. [PMID: 34401662 PMCID: PMC8350547 DOI: 10.1016/j.isci.2021.102878] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2020] [Revised: 04/13/2021] [Accepted: 07/15/2021] [Indexed: 12/12/2022] Open
Abstract
CHIP is an E3-ubiquitin ligase that contributes to healthy aging and has been characterized as neuroprotective. To elucidate dominant CHIP-dependent changes in protein steady-state levels in a patient-derived human neuronal model, CHIP function was ablated using gene-editing and an unbiased proteomic analysis conducted to compare knock-out and wild-type isogenic induced pluripotent stem cell (iPSC)-derived cortical neurons. Rather than a broad effect on protein homeostasis, loss of CHIP function impacted on a focused cohort of proteins from actin cytoskeleton signaling and membrane integrity networks. In support of the proteomics, CHIP knockout cells had enhanced sensitivity to induced membrane damage. We conclude that the major readout of CHIP function in cortical neurons derived from iPSC of a patient with elevate α-synuclein, Parkinson's disease and dementia, is the modulation of substrates involved in maintaining cellular "health". Thus, regulation of the actin cytoskeletal and membrane integrity likely contributes to the neuroprotective function(s) of CHIP.
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Affiliation(s)
- Catarina Dias
- Institute of Genetics and Cancer, University of Edinburgh, Edinburgh EH4 2XU, UK
- Centre for Regenerative Medicine, Institute for Stem Cell Research, School of Biological Sciences, The University of Edinburgh, Edinburgh EH16 4UU, UK
| | - Erisa Nita
- Institute of Genetics and Cancer, University of Edinburgh, Edinburgh EH4 2XU, UK
| | - Jakub Faktor
- Research Centre for Applied Molecular Oncology, Masaryk Memorial Cancer Institute, 656 53 Brno, Czech Republic
- University of Gdansk, International Centre for Cancer Vaccine Science, 80-822 Gdansk, Poland
| | - Ailish C. Tynan
- Institute of Genetics and Cancer, University of Edinburgh, Edinburgh EH4 2XU, UK
| | - Lenka Hernychova
- Research Centre for Applied Molecular Oncology, Masaryk Memorial Cancer Institute, 656 53 Brno, Czech Republic
| | - Borivoj Vojtesek
- Research Centre for Applied Molecular Oncology, Masaryk Memorial Cancer Institute, 656 53 Brno, Czech Republic
| | - Jesper Nylandsted
- Membrane Integrity Group, Danish Cancer Society Research Center, Strandboulevarden 49, 2100, Copenhagen, Denmark
| | - Ted R. Hupp
- Institute of Genetics and Cancer, University of Edinburgh, Edinburgh EH4 2XU, UK
- University of Gdansk, International Centre for Cancer Vaccine Science, 80-822 Gdansk, Poland
| | - Tilo Kunath
- Centre for Regenerative Medicine, Institute for Stem Cell Research, School of Biological Sciences, The University of Edinburgh, Edinburgh EH16 4UU, UK
| | - Kathryn L. Ball
- Institute of Genetics and Cancer, University of Edinburgh, Edinburgh EH4 2XU, UK
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3
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Kostan J, Pavšič M, Puž V, Schwarz TC, Drepper F, Molt S, Graewert MA, Schreiner C, Sajko S, van der Ven PFM, Onipe A, Svergun DI, Warscheid B, Konrat R, Fürst DO, Lenarčič B, Djinović-Carugo K. Molecular basis of F-actin regulation and sarcomere assembly via myotilin. PLoS Biol 2021; 19:e3001148. [PMID: 33844684 PMCID: PMC8062120 DOI: 10.1371/journal.pbio.3001148] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2020] [Revised: 04/22/2021] [Accepted: 02/16/2021] [Indexed: 12/25/2022] Open
Abstract
Sarcomeres, the basic contractile units of striated muscle cells, contain arrays of thin (actin) and thick (myosin) filaments that slide past each other during contraction. The Ig-like domain-containing protein myotilin provides structural integrity to Z-discs-the boundaries between adjacent sarcomeres. Myotilin binds to Z-disc components, including F-actin and α-actinin-2, but the molecular mechanism of binding and implications of these interactions on Z-disc integrity are still elusive. To illuminate them, we used a combination of small-angle X-ray scattering, cross-linking mass spectrometry, and biochemical and molecular biophysics approaches. We discovered that myotilin displays conformational ensembles in solution. We generated a structural model of the F-actin:myotilin complex that revealed how myotilin interacts with and stabilizes F-actin via its Ig-like domains and flanking regions. Mutant myotilin designed with impaired F-actin binding showed increased dynamics in cells. Structural analyses and competition assays uncovered that myotilin displaces tropomyosin from F-actin. Our findings suggest a novel role of myotilin as a co-organizer of Z-disc assembly and advance our mechanistic understanding of myotilin's structural role in Z-discs.
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Affiliation(s)
- Julius Kostan
- Department of Structural and Computational Biology, Max Perutz Labs, University of Vienna, Vienna, Austria
| | - Miha Pavšič
- Department of Chemistry and Biochemistry, Faculty of Chemistry and Chemical Technology, University of Ljubljana, Ljubljana, Slovenia
| | - Vid Puž
- Department of Chemistry and Biochemistry, Faculty of Chemistry and Chemical Technology, University of Ljubljana, Ljubljana, Slovenia
| | - Thomas C. Schwarz
- Department of Structural and Computational Biology, Max Perutz Labs, University of Vienna, Vienna, Austria
| | - Friedel Drepper
- Biochemistry and Functional Proteomics, Institute of Biology II, Faculty of Biology, University of Freiburg, Freiburg, Germany
- Signalling Research Centres BIOSS and CIBSS, University of Freiburg, Freiburg, Germany
| | - Sibylle Molt
- Institute for Cell Biology, Department of Molecular Cell Biology, University of Bonn, Bonn, Germany
| | | | - Claudia Schreiner
- Department of Structural and Computational Biology, Max Perutz Labs, University of Vienna, Vienna, Austria
| | - Sara Sajko
- Department of Structural and Computational Biology, Max Perutz Labs, University of Vienna, Vienna, Austria
| | - Peter F. M. van der Ven
- Institute for Cell Biology, Department of Molecular Cell Biology, University of Bonn, Bonn, Germany
| | - Adekunle Onipe
- Department of Structural and Computational Biology, Max Perutz Labs, University of Vienna, Vienna, Austria
| | - Dmitri I. Svergun
- European Molecular Biology Laboratory, Hamburg Unit, c/o DESY, Hamburg, Germany
| | - Bettina Warscheid
- Biochemistry and Functional Proteomics, Institute of Biology II, Faculty of Biology, University of Freiburg, Freiburg, Germany
- Signalling Research Centres BIOSS and CIBSS, University of Freiburg, Freiburg, Germany
| | - Robert Konrat
- Department of Structural and Computational Biology, Max Perutz Labs, University of Vienna, Vienna, Austria
| | - Dieter O. Fürst
- Institute for Cell Biology, Department of Molecular Cell Biology, University of Bonn, Bonn, Germany
| | - Brigita Lenarčič
- Department of Chemistry and Biochemistry, Faculty of Chemistry and Chemical Technology, University of Ljubljana, Ljubljana, Slovenia
- Department of Biochemistry, Molecular and Structural Biology, Jožef Stefan Institute, Ljubljana, Slovenia
| | - Kristina Djinović-Carugo
- Department of Structural and Computational Biology, Max Perutz Labs, University of Vienna, Vienna, Austria
- Department of Chemistry and Biochemistry, Faculty of Chemistry and Chemical Technology, University of Ljubljana, Ljubljana, Slovenia
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4
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Vattepu R, Klausmeyer RA, Ayella A, Yadav R, Dille JT, Saiz SV, Beck MR. Conserved tryptophan mutation disrupts structure and function of immunoglobulin domain revealing unusual tyrosine fluorescence. Protein Sci 2020; 29:2062-2074. [PMID: 32797644 DOI: 10.1002/pro.3929] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2020] [Revised: 08/04/2020] [Accepted: 08/05/2020] [Indexed: 12/27/2022]
Abstract
Immunoglobulin (Ig) domains are the most prevalent protein domain structure and share a highly conserved folding pattern; however, this structural family of proteins is also the most diverse in terms of biological roles and tissue expression. Ig domains vary significantly in amino acid sequence but share a highly conserved tryptophan in the hydrophobic core of this beta-stranded protein. Palladin is an actin binding and bundling protein that has five Ig domains and plays an important role in normal cell adhesion and motility. Mutation of the core tryptophan in one Ig domain of palladin has been identified in a pancreatic cancer cell line, suggesting a crucial role for this sole tryptophan in palladin Ig domain structure, stability, and function. We found that actin binding and bundling was not completely abolished with removal of this tryptophan despite a partially unfolded structure and significantly reduced stability of the mutant Ig domain as shown by circular dichroism investigations. In addition, this mutant palladin domain displays a tryptophan-like fluorescence attributed to an anomalous tyrosine emission at 341 nm. Our results indicate that this emission originates from a tyrosinate that may be formed in the excited ground state by proton transfer to a nearby aspartic acid residue. Furthermore, this study emphasizes the importance of tryptophan in protein structural stability and illustrates how tyrosinate emission contributions may be overlooked during the interpretation of the fluorescence properties of proteins.
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Affiliation(s)
- Ravi Vattepu
- Chemistry Department, Wichita State University, Wichita, Kansas, USA
| | | | - Allan Ayella
- Chemistry Department, Wichita State University, Wichita, Kansas, USA.,Chemistry Department, Washburn University, Topeka, Kansas, USA
| | - Rahul Yadav
- Chemistry Department, Wichita State University, Wichita, Kansas, USA
| | - Joseph T Dille
- Chemistry Department, Wichita State University, Wichita, Kansas, USA
| | - Stan V Saiz
- Chemistry Department, Wichita State University, Wichita, Kansas, USA
| | - Moriah R Beck
- Chemistry Department, Wichita State University, Wichita, Kansas, USA
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5
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Yang T, Yang WX. The dynamics and regulation of microfilament during spermatogenesis. Gene 2020; 744:144635. [PMID: 32244053 DOI: 10.1016/j.gene.2020.144635] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2019] [Revised: 02/28/2020] [Accepted: 03/30/2020] [Indexed: 12/22/2022]
Abstract
Spermatogenesis is a highly complex physiological process which contains spermatogonia proliferation, spermatocyte meiosis and spermatid morphogenesis. In the past decade, actin binding proteins and signaling pathways which are critical for regulating the actin cytoskeleton in testis had been found. In this review, we summarized 5 actin-binding proteins that have been proven to play important roles in the seminiferous epithelium. Lack of them perturbs spermatids polarity and the transport of spermatids. The loss of Arp2/3 complex, Formin1, Eps8, Palladin and Plastin3 cause sperm release failure suggesting their irreplaceable role in spermatogenesis. Actin regulation relies on multiple signal pathways. The PI3K/Akt signaling pathway positively regulate the mTOR pathway to promote actin reorganization in seminiferous epithelium. Conversely, TSC1/TSC2 complex, the upstream of mTOR, is activated by the LKB1/AMPK pathway to inhibit cell proliferation, differentiation and migration. The increasing researches focus on the function of actin binding proteins (ABPs), however, their collaborative regulation of actin patterns and potential regulatory signaling networks remains unclear. We reviewed ABPs that play important roles in mammalian spermatogenesis and signal pathways involved in the regulation of microfilaments. We suggest that more relevant studies should be performed in the future.
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Affiliation(s)
- Tong Yang
- The Sperm Laboratory, College of Life Sciences, Zhejiang University, Hangzhou 310058, China
| | - Wan-Xi Yang
- The Sperm Laboratory, College of Life Sciences, Zhejiang University, Hangzhou 310058, China.
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6
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Nicholson L, Lindsay L, Murphy CR. Change in distribution of cytoskeleton-associated proteins, lasp-1 and palladin, during uterine receptivity in the rat endometrium. Reprod Fertil Dev 2019; 30:1482-1490. [PMID: 29739492 DOI: 10.1071/rd17530] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2017] [Accepted: 04/16/2018] [Indexed: 11/23/2022] Open
Abstract
The epithelium of the uterine lumen is the first point of contact with the blastocyst before implantation. To facilitate pregnancy, these uterine epithelial cells (UECs) undergo morphological changes specific to the receptive uterus. These changes include basal, lateral and apical alterations in the plasma membrane of UECs. This study looked at the cytoskeletal and focal adhesion-associated proteins, lasp-1 and palladin, in the uterus during early pregnancy in the rat. Two palladin isoforms, 140 kDa and 90 kDa, were analysed, with the migration-associated 140-kDa isoform increasing significantly at the time of implantation when compared with the time of fertilisation. Lasp-1 was similarly increased at this time, whilst also being located predominantly apically and laterally in the UECs, suggesting a role in the initial contact between the UECs and the blastocyst. This is the first study to investigate palladin and lasp-1 in the uterine luminal epithelium and suggests an importance for these cytoskeletal proteins in the morphological changes the UECs undergo for pregnancy to occur.
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Affiliation(s)
- Leigh Nicholson
- Cell and Reproductive Biology Laboratory, Discipline of Anatomy and Histology, School of Medical Sciences, University of Sydney, Camperdown, NSW 2050, Australia
| | - Laura Lindsay
- Cell and Reproductive Biology Laboratory, Discipline of Anatomy and Histology, School of Medical Sciences, University of Sydney, Camperdown, NSW 2050, Australia
| | - Christopher R Murphy
- Cell and Reproductive Biology Laboratory, Discipline of Anatomy and Histology, School of Medical Sciences, University of Sydney, Camperdown, NSW 2050, Australia
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7
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Crowley EL, Rafferty SP. Review of lactose-driven auto-induction expression of isotope-labelled proteins. Protein Expr Purif 2019; 157:70-85. [PMID: 30708035 DOI: 10.1016/j.pep.2019.01.007] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2019] [Accepted: 01/18/2019] [Indexed: 02/06/2023]
Abstract
NMR is an important method in the structural and functional characterization of proteins, but such experiments typically require isotopic labelling because of the low natural abundance of the nuclei of interest. Isotope-labelled protein for NMR experiments is typically obtained from IPTG-inducible bacterial expression systems in a minimal media that contains labelled carbon or nitrogen sources. Optimization of expression conditions is crucial yet challenging; large amounts of labelled protein are desired, yet protein yields are lower in minimal media, while the labelled precursors are expensive. Faced with these challenges there is a growing body of literature that apply innovative methods of induction to optimize the yield of isotope-labelled protein. A promising technique is lactose-driven auto-induction as it mitigates user intervention and can lead to higher protein yields. This review assesses the current advances and limitations surrounding the ability of researchers to isotope label proteins using auto-induction, and it identifies key components for optimization.
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Affiliation(s)
- Erika L Crowley
- Environmental and Life Sciences Graduate Program, Trent University, 1600 West Bank Drive, Peterborough, ON, K9J 0G2, Canada.
| | - Steven P Rafferty
- Department of Chemistry, Trent University, 1600 West Bank Drive, Peterborough, ON, K9J 0G2, Canada.
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8
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Palladin is a novel microtubule-associated protein responsible for spindle orientation. Sci Rep 2017; 7:11806. [PMID: 28924223 PMCID: PMC5603589 DOI: 10.1038/s41598-017-12051-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2017] [Accepted: 08/25/2017] [Indexed: 11/26/2022] Open
Abstract
Mitotic spindles, which consist of microtubules (MTs) and associated proteins, play critical roles in controlling cell division and maintaining tissue homeostasis. The orientation of the mitotic spindle is closely related with the duration of mitosis. However, the molecular mechanism in regulating the orientation of the mitotic spindles is largely undefined. In this study, we found that Palladin is a novel MT-associated protein and regulator of spindle orientation, which maintains proper spindle orientation by stabilizing astral MTs. Palladin depletion distorted spindle orientation, prolonged the metaphase, and impaired proliferation of HeLa cells. Results showed that Palladin depletion-induced spindle misorientation and astral MT instability could be rescued by constitutively active AKT1 or dominant negative GSK3β. Our findings revealed that Palladin regulates spindle orientation and mitotic progression mainly through the AKT1–GSK3β pathway.
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9
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Sun HM, Chen XL, Chen XJ, Liu J, Ma L, Wu HY, Huang QH, Xi XD, Yin T, Zhu J, Chen Z, Chen SJ. PALLD Regulates Phagocytosis by Enabling Timely Actin Polymerization and Depolymerization. THE JOURNAL OF IMMUNOLOGY 2017; 199:1817-1826. [PMID: 28739877 DOI: 10.4049/jimmunol.1602018] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/02/2016] [Accepted: 06/12/2017] [Indexed: 12/28/2022]
Abstract
PALLD is an actin cross-linker supporting cellular mechanical tension. However, its involvement in the regulation of phagocytosis, a cellular activity essential for innate immunity and physiological tissue turnover, is unclear. We report that PALLD is highly induced along with all-trans-retinoic acid-induced maturation of myeloid leukemia cells, to promote Ig- or complement-opsonized phagocytosis. PALLD mechanistically facilitates phagocytic receptor clustering by regulating actin polymerization and c-Src dynamic activation during particle binding and early phagosome formation. PALLD is also required at the nascent phagosome to recruit phosphatase oculocerebrorenal syndrome of Lowe, which regulates phosphatidylinositol-4,5-bisphosphate hydrolysis and actin depolymerization to complete phagosome closure. Collectively, our results show a new function for PALLD as a crucial regulator of the early phase of phagocytosis by elaborating dynamic actin polymerization and depolymerization.
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Affiliation(s)
- Hai-Min Sun
- State Key Laboratory of Medical Genomics, Shanghai Institute of Hematology, RuiJin Hospital Affiliated to Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China
| | - Xin-Lei Chen
- State Key Laboratory of Medical Genomics, Shanghai Institute of Hematology, RuiJin Hospital Affiliated to Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China
| | - Xin-Jie Chen
- State Key Laboratory of Medical Genomics, Shanghai Institute of Hematology, RuiJin Hospital Affiliated to Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China
| | - Jin Liu
- State Key Laboratory of Medical Genomics, Shanghai Institute of Hematology, RuiJin Hospital Affiliated to Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China
| | - Lie Ma
- State Key Laboratory of Medical Genomics, Shanghai Institute of Hematology, RuiJin Hospital Affiliated to Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China
| | - Hai-Yan Wu
- State Key Laboratory of Medical Genomics, Shanghai Institute of Hematology, RuiJin Hospital Affiliated to Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China
| | - Qiu-Hua Huang
- State Key Laboratory of Medical Genomics, Shanghai Institute of Hematology, RuiJin Hospital Affiliated to Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China
| | - Xiao-Dong Xi
- State Key Laboratory of Medical Genomics, Shanghai Institute of Hematology, RuiJin Hospital Affiliated to Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China
| | - Tong Yin
- State Key Laboratory of Medical Genomics, Shanghai Institute of Hematology, RuiJin Hospital Affiliated to Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China
| | - Jiang Zhu
- State Key Laboratory of Medical Genomics, Shanghai Institute of Hematology, RuiJin Hospital Affiliated to Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China
| | - Zhu Chen
- State Key Laboratory of Medical Genomics, Shanghai Institute of Hematology, RuiJin Hospital Affiliated to Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China
| | - Sai-Juan Chen
- State Key Laboratory of Medical Genomics, Shanghai Institute of Hematology, RuiJin Hospital Affiliated to Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China
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10
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Kajiura K, Takizawa H, Morimoto Y, Masuda K, Tsuboi M, Kishibuchi R, Wusiman N, Sawada T, Kawakita N, Toba H, Yoshida M, Kawakami Y, Naruto T, Imoto I, Tangoku A, Kondo K. Frequent silencing of RASSF1A by DNA methylation in thymic neuroendocrine tumours. Lung Cancer 2017; 111:116-123. [PMID: 28838380 DOI: 10.1016/j.lungcan.2017.05.019] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2017] [Revised: 05/20/2017] [Accepted: 05/20/2017] [Indexed: 01/12/2023]
Abstract
OBJECTIVES Aberrant methylation of promoter CpG islands (CGIs) of tumour suppressor genes is a common epigenetic mechanism underlying cancer pathogenesis. The methylation patterns of thymic tumours have not been studied in detail since such tumours are rare. Herein, we sought to identify genes that could serve as epigenetic targets for thymic neuroendocrine tumour (NET) therapy. MATERIALS AND METHODS Genome-wide screening for aberrantly methylated CGIs was performed in three NET samples, seven thymic carcinoma (TC) samples, and eight type-B3 thymoma samples. The methylation status of thymic epithelial tumours (TETs) samples was validated by pyrosequencing in a larger cohort. The expression status was analysed by quantitative polymerase chain reaction (PCR) and immunohistochemistry. RESULTS We identified a CGI on a novel gene, RASSF1A, which was strongly hypermethylated in NET, but not in thymic carcinoma or B3 thymoma. RASSF1A was identified as a candidate gene statistically and bibliographically, as it showed frequent CGI hypermethylation in NET by genome-wide screening. Pyrosequencing confirmed significant hypermethylation of a RASSF1A CGI in NET. Low-grade NET tissue was more strongly methylated than high-grade NET. Quantitative PCR and immunohistochemical staining revealed that RASSF1A mRNA and protein expression levels were negatively regulated by DNA methylation. CONCLUSIONS RASSF1A is a tumour suppressor gene epigenetically dysregulated in NET. Aberrant methylation of RASSF1A has been reported in various tumours, but this is the first report of RASSF1A hypermethylation in TETs. RASSF1A may represent an epigenetic therapeutic target in thymic NET.
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Affiliation(s)
- Koichiro Kajiura
- Department of Thoracic, Endocrine and Oncological Surgery, Graduate School of Biomedical Sciences, Tokushima University Graduate School, Tokushima city 770-8503, Japan; Department of Human Genetics, Graduate School of Biomedical Sciences, Tokushima University Graduate School, Tokushima city 770-8503, Japan.
| | - Hiromitsu Takizawa
- Department of Thoracic, Endocrine and Oncological Surgery, Graduate School of Biomedical Sciences, Tokushima University Graduate School, Tokushima city 770-8503, Japan.
| | - Yuki Morimoto
- Department of Oncological Medical Services, Graduate School of Biomedical Sciences, Tokushima University Graduate School, Tokushima city 770-8503, Japan.
| | - Kiyoshi Masuda
- Department of Human Genetics, Graduate School of Biomedical Sciences, Tokushima University Graduate School, Tokushima city 770-8503, Japan.
| | - Mitsuhiro Tsuboi
- Department of Thoracic, Endocrine and Oncological Surgery, Graduate School of Biomedical Sciences, Tokushima University Graduate School, Tokushima city 770-8503, Japan.
| | - Reina Kishibuchi
- Department of Oncological Medical Services, Graduate School of Biomedical Sciences, Tokushima University Graduate School, Tokushima city 770-8503, Japan.
| | - Nuliamina Wusiman
- Department of Oncological Medical Services, Graduate School of Biomedical Sciences, Tokushima University Graduate School, Tokushima city 770-8503, Japan.
| | - Toru Sawada
- Department of Thoracic, Endocrine and Oncological Surgery, Graduate School of Biomedical Sciences, Tokushima University Graduate School, Tokushima city 770-8503, Japan.
| | - Naoya Kawakita
- Department of Thoracic, Endocrine and Oncological Surgery, Graduate School of Biomedical Sciences, Tokushima University Graduate School, Tokushima city 770-8503, Japan.
| | - Hiroaki Toba
- Department of Thoracic, Endocrine and Oncological Surgery, Graduate School of Biomedical Sciences, Tokushima University Graduate School, Tokushima city 770-8503, Japan.
| | - Mitsuteru Yoshida
- Department of Thoracic, Endocrine and Oncological Surgery, Graduate School of Biomedical Sciences, Tokushima University Graduate School, Tokushima city 770-8503, Japan.
| | - Yukikiyo Kawakami
- Department of Thoracic, Endocrine and Oncological Surgery, Graduate School of Biomedical Sciences, Tokushima University Graduate School, Tokushima city 770-8503, Japan.
| | - Takuya Naruto
- Department of Human Genetics, Graduate School of Biomedical Sciences, Tokushima University Graduate School, Tokushima city 770-8503, Japan.
| | - Issei Imoto
- Department of Human Genetics, Graduate School of Biomedical Sciences, Tokushima University Graduate School, Tokushima city 770-8503, Japan.
| | - Akira Tangoku
- Department of Thoracic, Endocrine and Oncological Surgery, Graduate School of Biomedical Sciences, Tokushima University Graduate School, Tokushima city 770-8503, Japan.
| | - Kazuya Kondo
- Department of Oncological Medical Services, Graduate School of Biomedical Sciences, Tokushima University Graduate School, Tokushima city 770-8503, Japan.
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