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Ma Y, Hou J, Huang D, Zhang Y, Liu Z, Tian M. Expression of protein phosphatase 4 in different tissues under hypoxia. INDIAN J PATHOL MICR 2023; 66:577-583. [PMID: 37530343 DOI: 10.4103/ijpm.ijpm_1179_21] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/03/2023] Open
Abstract
Relevant research data shows that there is a certain degree of energy metabolism imbalance in highland residents. Protein phosphatase 4 (PP4) has been found as a new factor in the regulation of sugar and lipid metabolism. Here, we investigate the differential expression of PP4 at a simulated altitude of 4,500 m in the heart, lung, and brain tissues of rats. A hypoxic plateau rat model was established using an animal decompression chamber. A blood routine test was performed by an animal blood cell analyzer on rats cultured for different hypoxia periods at 4,500 m above sea level. Quantitative polymerase chain reaction (qPCR) and western blot were used to detect the changes of protein phosphatase 4 catalytic subunit (PP4C) gene and protein in heart, lung, and brain tissues. The PP4C gene with the highest expression level found in rats slowly entering the high altitude area (20 m-2200 m-7 d-4500 m-3 d) was about twice as high as the low elevation group (20 m above sea level). The simulated high-altitude hypoxia induced an increase of PP4C expression level in all tissues, and the expression in the lung tissue was twice as expressed as heart and brain tissue at high altitude (P < 0.05). These results suggest that the PP4 phosphatase complex is ubiquitously expressed in rat tissues and likely involved in adaptation to or disease associated with high-altitude hypoxia.
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Affiliation(s)
- Yanyan Ma
- Central Laboratory, Affiliated Hospital of Qinghai University, Tongren Road 29, Qinghai Province; Medical College of Qinghai University, Xining, Qinghai Province, China
| | - Jing Hou
- Central Laboratory, Affiliated Hospital of Qinghai University, Tongren Road 29, Qinghai Province, China
| | - Dengliang Huang
- Central Laboratory, Affiliated Hospital of Qinghai University, Tongren Road 29, Qinghai Province, China
| | - Yaogang Zhang
- Central Laboratory, Affiliated Hospital of Qinghai University, Tongren Road 29, Qinghai Province, China
| | - Zhe Liu
- Central Laboratory, Affiliated Hospital of Qinghai University, Tongren Road 29, Qinghai Province, China
| | - Meiyuan Tian
- Central Laboratory, Affiliated Hospital of Qinghai University, Tongren Road 29, Qinghai Province; Medical College of Qinghai University, Xining, Qinghai Province, China
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2
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Kokot T, Köhn M. Emerging insights into serine/threonine-specific phosphoprotein phosphatase function and selectivity. J Cell Sci 2022; 135:277104. [DOI: 10.1242/jcs.259618] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
ABSTRACT
Protein phosphorylation on serine and threonine residues is a widely distributed post-translational modification on proteins that acts to regulate their function. Phosphoprotein phosphatases (PPPs) contribute significantly to a plethora of cellular functions through the accurate dephosphorylation of phosphorylated residues. Most PPPs accomplish their purpose through the formation of complex holoenzymes composed of a catalytic subunit with various regulatory subunits. PPP holoenzymes then bind and dephosphorylate substrates in a highly specific manner. Despite the high prevalence of PPPs and their important role for cellular function, their mechanisms of action in the cell are still not well understood. Nevertheless, substantial experimental advancements in (phospho-)proteomics, structural and computational biology have contributed significantly to a better understanding of PPP biology in recent years. This Review focuses on recent approaches and provides an overview of substantial new insights into the complex mechanism of PPP holoenzyme regulation and substrate selectivity.
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Affiliation(s)
- Thomas Kokot
- Signalling Research Centres BIOSS and CIBSS, University of Freiburg 1 , Freiburg 79104 , Germany
- University of Freiburg, 2 Faculty of Biology , Freiburg 79104 , Germany
| | - Maja Köhn
- Signalling Research Centres BIOSS and CIBSS, University of Freiburg 1 , Freiburg 79104 , Germany
- University of Freiburg, 2 Faculty of Biology , Freiburg 79104 , Germany
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3
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Sapir T, Kshirsagar A, Gorelik A, Olender T, Porat Z, Scheffer IE, Goldstein DB, Devinsky O, Reiner O. Heterogeneous nuclear ribonucleoprotein U (HNRNPU) safeguards the developing mouse cortex. Nat Commun 2022; 13:4209. [PMID: 35864088 PMCID: PMC9304408 DOI: 10.1038/s41467-022-31752-z] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2021] [Accepted: 06/30/2022] [Indexed: 11/20/2022] Open
Abstract
HNRNPU encodes the heterogeneous nuclear ribonucleoprotein U, which participates in RNA splicing and chromatin organization. Microdeletions in the 1q44 locus encompassing HNRNPU and other genes and point mutations in HNRNPU cause brain disorders, including early-onset seizures and severe intellectual disability. We aimed to understand HNRNPU’s roles in the developing brain. Our work revealed that HNRNPU loss of function leads to rapid cell death of both postmitotic neurons and neural progenitors, with an apparent higher sensitivity of the latter. Further, expression and alternative splicing of multiple genes involved in cell survival, cell motility, and synapse formation are affected following Hnrnpu’s conditional truncation. Finally, we identified pharmaceutical and genetic agents that can partially reverse the loss of cortical structures in Hnrnpu mutated embryonic brains, ameliorate radial neuronal migration defects and rescue cultured neural progenitors’ cell death. HNRNPU is an RNA splicing protein associated with brain disorders such as early onset seizures. Here they show that HNRNPU functions to maintain neural progenitors and their progeny by regulating splicing of key neuronal genes.
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Affiliation(s)
- Tamar Sapir
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot, Israel
| | - Aditya Kshirsagar
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot, Israel
| | - Anna Gorelik
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot, Israel
| | - Tsviya Olender
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot, Israel
| | - Ziv Porat
- Flow Cytometry Unit, Life Sciences Core Facilities, Weizmann Institute of Science, Rehovot, Israel
| | - Ingrid E Scheffer
- The University of Melbourne, Austin Health and Royal Children's Hospital, Florey and Murdoch Children's Research Institutes, Melbourne, VIC, Australia
| | - David B Goldstein
- Institute for Genomic Medicine, Columbia University, New York, NY, USA
| | | | - Orly Reiner
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot, Israel.
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Huang X, Yang G, Zhao L, Yuan H, Chen H, Shen T, Tang W, Man Y, Ma J, Ma Y, Dou L, Li J. Protein Phosphatase 4 Promotes Hepatocyte Lipoapoptosis by Regulating RAC1/MLK3/JNK Pathway. OXIDATIVE MEDICINE AND CELLULAR LONGEVITY 2021; 2021:5550498. [PMID: 34221233 PMCID: PMC8221892 DOI: 10.1155/2021/5550498] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/09/2021] [Revised: 04/08/2021] [Accepted: 05/19/2021] [Indexed: 12/30/2022]
Abstract
Lipotoxicity-induced apoptosis, also referred to as lipoapoptosis, is one of the important initial factors promoting the progression from hepatosteatosis to nonalcoholic steatohepatitis (NASH). Saturated free fatty acids (SFAs), which are increased significantly in NASH, are directly hepatotoxic which induce hepatocyte lipoapoptosis. Previously, we reported that protein phosphatase 4 (PP4) was a novel regulator of hepatic insulin resistance and lipid metabolism, but its role in hepatic lipoapoptosis remains unexplored. In this study, we found out that PP4 was upregulated in the livers of western diet-fed-induced NASH mice and SFA-treated murine primary hepatocytes and HepG2 cells. In addition, we found for the first time that suppression of PP4 decreased SFA-induced JNK activation and expression of key modulators of hepatocyte lipoapoptosis including p53-upregulated modulator of apoptosis (PUMA) and Bcl-2-interacting mediator (Bim) and reduced hepatocyte lipoapoptosis level as well both in vitro and in vivo. Further study revealed that PP4 induced JNK activation and lipoapoptosis-related protein expression by regulating the RAC1/MLK3 pathway instead of the PERK/CHOP pathway. The effects of palmitate-treated and PP4-induced lipoapoptosis pathway activation were largely abolished by RAC1 inhibition. Moreover, we identified that PP4 interacted with RAC1 and regulated GTPase activity of RAC1. In conclusion, these results demonstrated that PP4 was a novel regulator of hepatocyte lipoapoptosis and mediated hepatocyte lipoapoptosis by regulating the RAC1/MLK3/JNK signaling pathway. Our finding provided new insights into the mechanisms of this process.
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Affiliation(s)
- Xiuqing Huang
- The Key Laboratory of Geriatrics, Beijing Institute of Geriatrics, Beijing Hospital, National Center of Gerontology, National Health Commission; Institute of Geriatric Medicine, Chinese Academy of Medical Sciences, Beijing 100730, China
| | - Guang Yang
- The Key Laboratory of Geriatrics, Beijing Institute of Geriatrics, Beijing Hospital, National Center of Gerontology, National Health Commission; Institute of Geriatric Medicine, Chinese Academy of Medical Sciences, Beijing 100730, China
| | - Li Zhao
- Department of Gastroenterology, Beijing Hospital, National Center of Gerontology, Institute of Geriatric Medicine, Chinese Academy of Medical Sciences, Beijing 100730, China
| | - Huiping Yuan
- The Key Laboratory of Geriatrics, Beijing Institute of Geriatrics, Beijing Hospital, National Center of Gerontology, National Health Commission; Institute of Geriatric Medicine, Chinese Academy of Medical Sciences, Beijing 100730, China
| | - Hao Chen
- The Key Laboratory of Geriatrics, Beijing Institute of Geriatrics, Beijing Hospital, National Center of Gerontology, National Health Commission; Institute of Geriatric Medicine, Chinese Academy of Medical Sciences, Beijing 100730, China
| | - Tao Shen
- The Key Laboratory of Geriatrics, Beijing Institute of Geriatrics, Beijing Hospital, National Center of Gerontology, National Health Commission; Institute of Geriatric Medicine, Chinese Academy of Medical Sciences, Beijing 100730, China
| | - Weiqing Tang
- The Key Laboratory of Geriatrics, Beijing Institute of Geriatrics, Beijing Hospital, National Center of Gerontology, National Health Commission; Institute of Geriatric Medicine, Chinese Academy of Medical Sciences, Beijing 100730, China
| | - Yong Man
- The Key Laboratory of Geriatrics, Beijing Institute of Geriatrics, Beijing Hospital, National Center of Gerontology, National Health Commission; Institute of Geriatric Medicine, Chinese Academy of Medical Sciences, Beijing 100730, China
| | - Jiarui Ma
- The Key Laboratory of Geriatrics, Beijing Institute of Geriatrics, Beijing Hospital, National Center of Gerontology, National Health Commission; Institute of Geriatric Medicine, Chinese Academy of Medical Sciences, Beijing 100730, China
| | - Yanyan Ma
- Department of Scientific Research, Qinghai University Affiliated Hospital, Xining 810001, China
| | - Lin Dou
- The Key Laboratory of Geriatrics, Beijing Institute of Geriatrics, Beijing Hospital, National Center of Gerontology, National Health Commission; Institute of Geriatric Medicine, Chinese Academy of Medical Sciences, Beijing 100730, China
| | - Jian Li
- The Key Laboratory of Geriatrics, Beijing Institute of Geriatrics, Beijing Hospital, National Center of Gerontology, National Health Commission; Institute of Geriatric Medicine, Chinese Academy of Medical Sciences, Beijing 100730, China
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Park J, Lee DH. Functional roles of protein phosphatase 4 in multiple aspects of cellular physiology: a friend and a foe. BMB Rep 2021. [PMID: 32192570 PMCID: PMC7196183 DOI: 10.5483/bmbrep.2020.53.4.019] [Citation(s) in RCA: 27] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Protein phosphatase 4 (PP4), one of serine/threonine phosphatases, is involved in many critical cellular pathways, including DNA damage response (DNA repair, cell cycle regulation, and apoptosis), tumorigenesis, cell migration, immune response, stem cell development, glucose metabolism, and diabetes. PP4 has been steadily studied over the past decade about wide spectrum of physiological activities in cells. Given the many vital functions in cells, PP4 has great potential to develop into the finding of key working mechanisms and effective treatments for related diseases such as cancer and diabetes. In this review, we provide an overview of the cellular and molecular mechanisms by which PP4 impacts and also discuss the functional significance of it in cell health.
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Affiliation(s)
- Jaehong Park
- School of Biological Sciences and Biotechnology Graduate School, Chonnam National University, Gwangju 61186, Korea
| | - Dong-Hyun Lee
- Department of Biological Sciences, College of Natural Sciences, Chonnam National University, Gwangju 61186; Research Center of Ecomimetics, Chonnam National University, Gwangju 61186, Korea
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6
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Chen MY, Hsu WC, Hsu SC, Yang YS, Chuang TH, Lin WJ, Tan TH, Su YW. PP4 deficiency leads to DNA replication stress that impairs immunoglobulin class switch efficiency. Cell Death Differ 2018; 26:1221-1234. [PMID: 30237510 PMCID: PMC6748143 DOI: 10.1038/s41418-018-0199-z] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2018] [Revised: 07/30/2018] [Accepted: 08/27/2018] [Indexed: 01/02/2023] Open
Abstract
The serine/threonine phosphatase PP4 has been implicated in DNA damage repair and cell cycle regulation through its dephosphorylation of specific substrates. We previously showed that PP4 is required for mouse B cell development, germinal center (GC) formation and immunoglobulin (Ig) class switch recombination (CSR). Here, we investigate the mechanisms underlying this requirement and demonstrate that murine PP4-deficient B lymphocytes have a defect in cell proliferation. Strikingly, the DNA damage response pathway that involves ATM/p53 and is linked to cell cycle arrest and impaired cell survival is strongly induced in these mutant B cells. In response to LPS + IL-4, stimuli that trigger IgG1 production, these PP4-deficient B cells show inefficient phosphorylation of ATR, leading to reduced retention of γH2AX-NBS1 complexes at sites of DNA damage, and compromised switching to IgG1. However, beyond the cell proliferation phase, conditional deletion of PP4 under the control of AID/cre completely restores normal IgG1 production in mutant B cell cultures. In vivo, co-deletion of PP4 and p53 by AID/cre partially rescues switching to IgG1 in B cells of mice immunized with TNP-KLH. Our findings establish that PP4 is indispensable for preventing DNA replication stress that could interfere with CSR, thereby promoting antibody switching during the humoral immune response.
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Affiliation(s)
- Ming-Yu Chen
- Immunology Research Center, National Health Research Institutes (NHRI), Zhunan, Miaoli County, Taiwan
| | - Wei-Chan Hsu
- Immunology Research Center, National Health Research Institutes (NHRI), Zhunan, Miaoli County, Taiwan
| | - Shu-Ching Hsu
- National Institute of Infectious Diseases and Vaccinology, NHRI, Zhunan, Miaoli County, Taiwan.,Graduate Institute of Medicine, College of Medicine, Kaohsiung Medical University, Kaohsiung, Taiwan.,Department of Medical Research and Development, Chang Bing Show Chwan Memorial Hospital, Chang Hua, Taiwan
| | - Yu-Shao Yang
- National Institute of Infectious Diseases and Vaccinology, NHRI, Zhunan, Miaoli County, Taiwan
| | - Tsung-Hsien Chuang
- Immunology Research Center, National Health Research Institutes (NHRI), Zhunan, Miaoli County, Taiwan
| | - Wen-Jye Lin
- Immunology Research Center, National Health Research Institutes (NHRI), Zhunan, Miaoli County, Taiwan
| | - Tse-Hua Tan
- Immunology Research Center, National Health Research Institutes (NHRI), Zhunan, Miaoli County, Taiwan.,Department of Pathology & Immunology, Baylor College of Medicine, Houston, TX, USA
| | - Yu-Wen Su
- Immunology Research Center, National Health Research Institutes (NHRI), Zhunan, Miaoli County, Taiwan.
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7
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Sivakumar S, Gorbsky GJ. Phosphatase-regulated recruitment of the spindle- and kinetochore-associated (Ska) complex to kinetochores. Biol Open 2017; 6:1672-1679. [PMID: 28982702 PMCID: PMC5703607 DOI: 10.1242/bio.026930] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Kinetochores move chromosomes on dynamic spindle microtubules and regulate signaling of the spindle checkpoint. The spindle- and kinetochore-associated (Ska) complex, a hexamer composed of two copies of Ska1, Ska2 and Ska3, has been implicated in both roles. Phosphorylation of kinetochore components by the well-studied mitotic kinases Cdk1, Aurora B, Plk1, Mps1, and Bub1 regulate chromosome movement and checkpoint signaling. Roles for the opposing phosphatases are more poorly defined. Recently, we showed that the C terminus of Ska1 recruits protein phosphatase 1 (PP1) to kinetochores. Here we show that PP1 and protein phosphatase 2A (PP2A) both promote accumulation of Ska at kinetochores. Depletion of PP1 or PP2A by siRNA reduces Ska binding at kinetochores, impairs alignment of chromosomes to the spindle midplane, and causes metaphase delay or arrest, phenotypes that are also seen after depletion of Ska. Artificial tethering of PP1 to the outer kinetochore protein Nuf2 promotes Ska recruitment to kinetochores, and it reduces but does not fully rescue chromosome alignment and metaphase arrest defects seen after Ska depletion. We propose that Ska has multiple functions in promoting mitotic progression and that kinetochore-associated phosphatases function in a positive feedback cycle to reinforce Ska complex accumulation at kinetochores. Summary: Feedback between protein phosphatases and the spindle- and kinetochore-associated (Ska) complex regulates chromosome movement and the metaphase-to-anaphase cell cycle transition. This article has an associated First Person interview with the first author of the paper as part of the supplementary information.
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Affiliation(s)
- Sushama Sivakumar
- Cell Cycle and Cancer Biology Research Program, Oklahoma Medical Research Foundation, Oklahoma City, OK 73104, USA
| | - Gary J Gorbsky
- Cell Cycle and Cancer Biology Research Program, Oklahoma Medical Research Foundation, Oklahoma City, OK 73104, USA
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8
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Hall ET, Pradhan-Sundd T, Samnani F, Verheyen EM. The protein phosphatase 4 complex promotes the Notch pathway and wingless transcription. Biol Open 2017; 6:1165-1173. [PMID: 28652317 PMCID: PMC5576076 DOI: 10.1242/bio.025221] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
The Wnt/Wingless (Wg) pathway controls cell fate specification, tissue differentiation and organ development across organisms. Using an in vivo RNAi screen to identify novel kinase and phosphatase regulators of the Wg pathway, we identified subunits of the serine threonine phosphatase Protein Phosphatase 4 (PP4). Knockdown of the catalytic and regulatory subunits of PP4 cause reductions in the Wg pathway targets Senseless and Distal-less. We find that PP4 regulates the Wg pathway by controlling Notch-driven wg transcription. Genetic interaction experiments identified that PP4 likely promotes Notch signaling within the nucleus of the Notch-receiving cell. Although the PP4 complex is implicated in various cellular processes, its role in the regulation of Wg and Notch pathways was previously uncharacterized. Our study identifies a novel role of PP4 in regulating Notch pathway, resulting in aberrations in Notch-mediated transcriptional regulation of the Wingless ligand. Furthermore, we show that PP4 regulates proliferation independent of its interaction with Notch. Summary: The protein phosphatase 4 complex promotes Notch signaling and target gene expression during Drosophila wing development.
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Affiliation(s)
- Eric T Hall
- Department of Molecular Biology and Biochemistry, Centre for Cell Biology, Development and Disease, Simon Fraser University, British Columbia V5A 1S6, Canada
| | - Tirthadipa Pradhan-Sundd
- Department of Molecular Biology and Biochemistry, Centre for Cell Biology, Development and Disease, Simon Fraser University, British Columbia V5A 1S6, Canada
| | - Faaria Samnani
- Department of Molecular Biology and Biochemistry, Centre for Cell Biology, Development and Disease, Simon Fraser University, British Columbia V5A 1S6, Canada
| | - Esther M Verheyen
- Department of Molecular Biology and Biochemistry, Centre for Cell Biology, Development and Disease, Simon Fraser University, British Columbia V5A 1S6, Canada
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Shao X, Lin S, Peng Q, Shi S, Wei X, Zhang T, Lin Y. Tetrahedral DNA Nanostructure: A Potential Promoter for Cartilage Tissue Regeneration via Regulating Chondrocyte Phenotype and Proliferation. SMALL 2017; 13. [PMID: 28112870 DOI: 10.1002/smll.201602770] [Citation(s) in RCA: 73] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/19/2016] [Revised: 12/15/2016] [Indexed: 02/05/2023]
Affiliation(s)
- Xiaoru Shao
- State Key Laboratory of Oral Diseases; West China Hospital of Stomatology; Sichuan University; Chengdu 610041 P. R. China
| | - Shiyu Lin
- State Key Laboratory of Oral Diseases; West China Hospital of Stomatology; Sichuan University; Chengdu 610041 P. R. China
| | - Qiang Peng
- State Key Laboratory of Oral Diseases; West China Hospital of Stomatology; Sichuan University; Chengdu 610041 P. R. China
| | - Sirong Shi
- State Key Laboratory of Oral Diseases; West China Hospital of Stomatology; Sichuan University; Chengdu 610041 P. R. China
| | - Xueqin Wei
- State Key Laboratory of Oral Diseases; West China Hospital of Stomatology; Sichuan University; Chengdu 610041 P. R. China
| | - Tao Zhang
- State Key Laboratory of Oral Diseases; West China Hospital of Stomatology; Sichuan University; Chengdu 610041 P. R. China
| | - Yunfeng Lin
- State Key Laboratory of Oral Diseases; West China Hospital of Stomatology; Sichuan University; Chengdu 610041 P. R. China
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