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Vanderwolf K, Kyle C, Davy C. A review of sebum in mammals in relation to skin diseases, skin function, and the skin microbiome. PeerJ 2023; 11:e16680. [PMID: 38144187 PMCID: PMC10740688 DOI: 10.7717/peerj.16680] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2023] [Accepted: 11/24/2023] [Indexed: 12/26/2023] Open
Abstract
Diseases vary among and within species but the causes of this variation can be unclear. Immune responses are an important driver of disease variation, but mechanisms on how the body resists pathogen establishment before activation of immune responses are understudied. Skin surfaces of mammals are the first line of defense against abiotic stressors and pathogens, and skin attributes such as pH, microbiomes, and lipids influence disease outcomes. Sebaceous glands produce sebum composed of multiple types of lipids with species-specific compositions. Sebum affects skin barrier function by contributing to minimizing water loss, supporting thermoregulation, protecting against pathogens, and preventing UV-induced damage. Sebum also affects skin microbiome composition both via its antimicrobial properties, and by providing potential nutrient sources. Intra- and interspecific variation in sebum composition influences skin disease outcomes in humans and domestic mammal species but is not well-characterized in wildlife. We synthesized knowledge on sebum function in mammals in relation to skin diseases and the skin microbiome. We found that sebum composition was described for only 29 live, wild mammalian species. Sebum is important in dermatophilosis, various forms of dermatitis, demodicosis, and potentially white-nose syndrome. Sebum composition likely affects disease susceptibility, as lipid components can have antimicrobial functions against specific pathogens. It is unclear why sebum composition is species-specific, but both phylogeny and environmental effects may drive differences. Our review illustrates the role of mammal sebum function and influence on skin microbes in the context of skin diseases, providing a baseline for future studies to elucidate mechanisms of disease resistance beyond immune responses.
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Affiliation(s)
- Karen Vanderwolf
- Department of Environmental and Life Sciences, Trent University, Peterborough, Ontario, Canada
| | - Christopher Kyle
- Forensic Science Department, Trent University, Peterborough, Ontario, Canada
- Natural Resources DNA Profiling and Forensics Center, Trent University, Peterborough, Ontario, Canada
| | - Christina Davy
- Department of Environmental and Life Sciences, Trent University, Peterborough, Ontario, Canada
- Department of Biology, Carleton University, Ottawa, Ontario, Canada
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2
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Frommeyer TC, Gilbert MM, Brittain GV, Wu T, Nguyen TQ, Rohan CA, Travers JB. UVB-Induced Microvesicle Particle Release and Its Effects on the Cutaneous Microenvironment. Front Immunol 2022; 13:880850. [PMID: 35603177 PMCID: PMC9120817 DOI: 10.3389/fimmu.2022.880850] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2022] [Accepted: 04/04/2022] [Indexed: 12/14/2022] Open
Abstract
Ultraviolet B radiation (UVB) has profound effects on human skin that results in a broad spectrum of immunological local and systemic responses and is the major cause of skin carcinogenesis. One important area of study in photobiology is how UVB is translated into effector signals. As the skin is exposed to UVB light, subcellular microvesicle particles (MVP), a subtype of bioactive extracellular vesicles, are released causing a variety of local and systemic immunological effects. In this review, we highlight keratinocyte MVP release in keratinocytes in response to UVB. Specifically, Platelet-activating factor receptor agonists generated by UVB result in MVP released from keratinocytes. The downstream effects of MVP release include the ability of these subcellular particles to transport agents including the glycerophosphocholine-derived lipid mediator Platelet-activating factor (PAF). Moreover, even though UVB is only absorbed in the epidermis, it appears that PAF release from MVPs also mediates systemic immunosuppression and enhances tumor growth and metastasis. Tumor cells expressing PAF receptors can use this mechanism to evade chemotherapy responses, leading to treatment resistance for advanced cancers such as melanoma. Furthermore, novel pharmacological agents provide greater insight into the UVB-induced immune response pathway and a potential target for pharmacological intervention. This review outlines the need to more clearly elucidate the mechanism linking UVB-irradiation with the cutaneous immune response and its pathological manifestations. An improved understanding of this process can result in new insights and treatment strategies for UVB-related disorders from carcinogenesis to photosensitivity.
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Affiliation(s)
- Timothy C. Frommeyer
- Department of Pharmacology and Toxicology, Boonshoft School of Medicine at Wright State University, Dayton, OH, United States
| | - Michael M. Gilbert
- Department of Pharmacology and Toxicology, Boonshoft School of Medicine at Wright State University, Dayton, OH, United States
| | - Garrett V. Brittain
- Department of Pharmacology and Toxicology, Boonshoft School of Medicine at Wright State University, Dayton, OH, United States
| | - Tongfan Wu
- Department of Pharmacology and Toxicology, Boonshoft School of Medicine at Wright State University, Dayton, OH, United States
| | - Trang Q. Nguyen
- Department of Pharmacology and Toxicology, Boonshoft School of Medicine at Wright State University, Dayton, OH, United States
| | - Craig A. Rohan
- Department of Pharmacology and Toxicology, Boonshoft School of Medicine at Wright State University, Dayton, OH, United States
- Department of Dermatology, Boonshoft School of Medicine at Wright State University, Dayton, OH, United States
- Department of Medicine, Dayton Veterans Administration Medical Center, Dayton, OH, United States
| | - Jeffrey B. Travers
- Department of Pharmacology and Toxicology, Boonshoft School of Medicine at Wright State University, Dayton, OH, United States
- Department of Dermatology, Boonshoft School of Medicine at Wright State University, Dayton, OH, United States
- Department of Medicine, Dayton Veterans Administration Medical Center, Dayton, OH, United States
- *Correspondence: Jeffrey B. Travers,
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Dong L, Li Y, Wu H. Platelet activating-factor acetylhydrolase II: A member of phospholipase A2 family that hydrolyzes oxidized phospholipids. Chem Phys Lipids 2021; 239:105103. [PMID: 34116047 DOI: 10.1016/j.chemphyslip.2021.105103] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2021] [Revised: 05/09/2021] [Accepted: 06/05/2021] [Indexed: 10/21/2022]
Abstract
Intracellular platelet activating-factor acetylhydrolase type II (PAF-AH II) is a 40-kDa monomeric enzyme. It was originally identified as an enzyme that hydrolyzes the acetyl group of PAF (1-O-alkyl-2-acetyl-sn-glycero-3-phosphocholine). As a member of phospholipase A2 super family, PAF-AH II has broad substrate specificity. It can hydrolyze phospholipids with relatively short-length or oxidatively modified sn-2 chains which endows it with various functions such as protection against oxidative stress, transacetylase activity and producing lipid mediators. PAF-AH II has been proven to be involved in several diseases such as allergic diseases, oxidative stress-induced injury and ischemia injury, thus it has drawn more attention from researchers. In this paper, we outline an entire summary of PAF-AH II, including its structure, substrate specificity, activity assay, inhibitors and biological activities.
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Affiliation(s)
- Linyue Dong
- Shanghai University of Traditional Chinese Medicine, Shanghai, China
| | - Yiming Li
- Department of TCM Chemistry, Shanghai University of Traditional Chinese Medicine, Shanghai, 201203, China.
| | - Huali Wu
- Department of TCM Chemistry, Shanghai University of Traditional Chinese Medicine, Shanghai, 201203, China.
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4
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Wu Z, Hai E, Di Z, Ma R, Shang F, Wang Y, Wang M, Liang L, Rong Y, Pan J, Wu W, Su R, Wang Z, Wang R, Zhang Y, Li J. Using WGCNA (weighted gene co-expression network analysis) to identify the hub genes of skin hair follicle development in fetus stage of Inner Mongolia cashmere goat. PLoS One 2020; 15:e0243507. [PMID: 33351808 PMCID: PMC7755285 DOI: 10.1371/journal.pone.0243507] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2020] [Accepted: 11/20/2020] [Indexed: 12/11/2022] Open
Abstract
OBJECTIVE Mature hair follicles represent an important stage of hair follicle development, which determines the stability of hair follicle structure and its ability to enter the hair cycle. Here, we used weighted gene co-expression network analysis (WGCNA) to identify hub genes of mature skin and hair follicles in Inner Mongolian cashmere goats. METHODS We used transcriptome sequencing data for the skin of Inner Mongolian cashmere goats from fetal days 45-135 days, and divided the co expressed genes into different modules by WGCNA. Characteristic values were used to screen out modules that were highly expressed in mature skin follicles. Module hub genes were then selected based on the correlation coefficients between the gene and module eigenvalue, gene connectivity, and Gene Ontology (GO)/Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis. The results were confirmed by quantitative polymerase chain reaction (qPCR). RESULTS Ten modules were successfully defined, of which one, with a total of 3166 genes, was selected as a specific module through sample and gene expression pattern analyses. A total of 584 candidate hub genes in the module were screened by the correlation coefficients between the genes and module eigenvalue and gene connectivity. Finally, GO/KEGG functional enrichment analyses detected WNT10A as a key gene in the development and maturation of skin hair follicles in fetal Inner Mongolian cashmere goats. qPCR showed that the expression trends of 13 genes from seven fetal skin samples were consistent with the sequencing results, indicating that the sequencing results were reliable.n.
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Affiliation(s)
- Zhihong Wu
- College of Animal Science, Inner Mongolia Agricultural University, Hohhot, Inner Mongolia, China
| | - Erhan Hai
- College of Animal Science, Inner Mongolia Agricultural University, Hohhot, Inner Mongolia, China
| | - Zhengyang Di
- College of Animal Science, Inner Mongolia Agricultural University, Hohhot, Inner Mongolia, China
| | - Rong Ma
- College of Animal Science, Inner Mongolia Agricultural University, Hohhot, Inner Mongolia, China
| | - Fangzheng Shang
- College of Animal Science, Inner Mongolia Agricultural University, Hohhot, Inner Mongolia, China
| | - Yu Wang
- College of Veterinary Medicine, Inner Mongolia Agricultural University, Hohhot, Inner Mongolia, China
| | - Min Wang
- College of Animal Science, Inner Mongolia Agricultural University, Hohhot, Inner Mongolia, China
| | - Lili Liang
- College of Animal Science, Inner Mongolia Agricultural University, Hohhot, Inner Mongolia, China
| | - Youjun Rong
- College of Animal Science, Inner Mongolia Agricultural University, Hohhot, Inner Mongolia, China
| | - Jianfeng Pan
- College of Animal Science, Inner Mongolia Agricultural University, Hohhot, Inner Mongolia, China
| | - Wenbin Wu
- Zhenlai Hehe Animal Husbandry Development Co., Ltd, Baicheng, China
| | - Rui Su
- College of Animal Science, Inner Mongolia Agricultural University, Hohhot, Inner Mongolia, China
| | - Zhiying Wang
- College of Animal Science, Inner Mongolia Agricultural University, Hohhot, Inner Mongolia, China
| | - Ruijun Wang
- College of Animal Science, Inner Mongolia Agricultural University, Hohhot, Inner Mongolia, China
| | - Yanjun Zhang
- College of Animal Science, Inner Mongolia Agricultural University, Hohhot, Inner Mongolia, China
- Engineering Research Center for Goat Genetics and Breeding, Hohhot, Inner Mongolia Autonomous Region, China
- * E-mail: (JL); , (YZ)
| | - Jinquan Li
- College of Animal Science, Inner Mongolia Agricultural University, Hohhot, Inner Mongolia, China
- Key Laboratory of Animal Genetics, Breeding and Reproduction, Hohhot, Inner Mongolia Autonomous Region, China
- Key Laboratory of Mutton Sheep Genetics and Breeding, Ministry of Agriculture, Hohhot, China
- Engineering Research Center for Goat Genetics and Breeding, Hohhot, Inner Mongolia Autonomous Region, China
- * E-mail: (JL); , (YZ)
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5
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Narzt MS, Nagelreiter IM, Oskolkova O, Bochkov VN, Latreille J, Fedorova M, Ni Z, Sialana FJ, Lubec G, Filzwieser M, Laggner M, Bilban M, Mildner M, Tschachler E, Grillari J, Gruber F. A novel role for NUPR1 in the keratinocyte stress response to UV oxidized phospholipids. Redox Biol 2018; 20:467-482. [PMID: 30466060 PMCID: PMC6243031 DOI: 10.1016/j.redox.2018.11.006] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2018] [Revised: 10/30/2018] [Accepted: 11/08/2018] [Indexed: 02/08/2023] Open
Abstract
Ultraviolet light is the dominant environmental oxidative skin stressor and a major skin aging factor. We studied which oxidized phospholipid (OxPL) mediators would be generated in primary human keratinocytes (KC) upon exposure to ultraviolet A light (UVA) and investigated the contribution of OxPL to UVA responses. Mass spectrometric analysis immediately or 24 h post UV stress revealed significant changes in abundance of 173 and 84 lipid species, respectively. We identified known and novel lipid species including known bioactive and also potentially reactive carbonyl containing species. We found indication for selective metabolism and degradation of selected reactive lipids. Exposure to both UVA and to in vitro UVA - oxidized phospholipids activated, on transcriptome and proteome level, NRF2/antioxidant response signaling, lipid metabolizing enzyme expression and unfolded protein response (UPR) signaling. We identified NUPR1 as an upstream regulator of UVA/OxPL transcriptional stress responses and found this protein to be expressed in the epidermis. Silencing of NUPR1 resulted in augmented expression of antioxidant and lipid detoxification genes and disturbed the cell cycle, making it a potential key factor in skin reactive oxygen species (ROS) responses intimately involved in aging and pathology.
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Affiliation(s)
- Marie-Sophie Narzt
- Department of Dermatology, Medical University of Vienna, Vienna, Austria; Christian Doppler Laboratory for Biotechnology of Skin Aging, Austria
| | - Ionela-Mariana Nagelreiter
- Department of Dermatology, Medical University of Vienna, Vienna, Austria; Christian Doppler Laboratory for Biotechnology of Skin Aging, Austria
| | - Olga Oskolkova
- Institute of Pharmaceutical Sciences, University of Graz, Graz, Austria
| | - Valery N Bochkov
- Institute of Pharmaceutical Sciences, University of Graz, Graz, Austria
| | - Julie Latreille
- Department of Biology & Women's Beauty, Chanel, Pantin, France
| | - Maria Fedorova
- Institute of Bioanalytical Chemistry, Faculty of Chemistry, Universität Leipzig, Leipzig, Germany; Center for Biotechnology and Biomedicine, Universität Leipzig, Leipzig, Germany
| | - Zhixu Ni
- Institute of Bioanalytical Chemistry, Faculty of Chemistry, Universität Leipzig, Leipzig, Germany; Center for Biotechnology and Biomedicine, Universität Leipzig, Leipzig, Germany
| | - Fernando J Sialana
- Department of Pharmaceutical Chemistry, Faculty of Life Sciences, University of Vienna, Vienna, Austria
| | - Gert Lubec
- Paracelsus Medical University of Salzburg, Salzburg, Austria
| | - Manuel Filzwieser
- Christian Doppler Laboratory for Biotechnology of Skin Aging, Austria
| | - Maria Laggner
- Department of Ophthalmology and Optometry, Medical University of Vienna, Vienna, Austria
| | - Martin Bilban
- Department of Laboratory Medicine & Core Facility Genomics, Medical University of Vienna, Vienna, Austria
| | - Michael Mildner
- Department of Dermatology, Medical University of Vienna, Vienna, Austria
| | - Erwin Tschachler
- Department of Dermatology, Medical University of Vienna, Vienna, Austria
| | - Johannes Grillari
- Christian Doppler Laboratory for Biotechnology of Skin Aging, Austria; Department of Biotechnology, BOKU, University of Natural Resources and Life Sciences Vienna, Austria
| | - Florian Gruber
- Department of Dermatology, Medical University of Vienna, Vienna, Austria; Christian Doppler Laboratory for Biotechnology of Skin Aging, Austria.
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6
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Iqbal J, Zhang K, Jin N, Zhao Y, Liu Q, Ni J, Shen L. Selenium positively affects the proteome of 3 × Tg-AD mice cortex by altering the expression of various key proteins: unveiling the mechanistic role of selenium in AD prevention. J Neurosci Res 2018; 96:1798-1815. [DOI: 10.1002/jnr.24309] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2018] [Revised: 06/21/2018] [Accepted: 06/29/2018] [Indexed: 12/16/2022]
Affiliation(s)
- Javed Iqbal
- College of Life Sciences and Oceanography; Shenzhen University; Shenzhen P. R. China
| | - Kaoyuan Zhang
- College of Life Sciences and Oceanography; Shenzhen University; Shenzhen P. R. China
| | - Na Jin
- College of Life Sciences and Oceanography; Shenzhen University; Shenzhen P. R. China
| | - Yuxi Zhao
- College of Life Sciences and Oceanography; Shenzhen University; Shenzhen P. R. China
| | - Qiong Liu
- College of Life Sciences and Oceanography; Shenzhen University; Shenzhen P. R. China
| | - Jiazuan Ni
- College of Life Sciences and Oceanography; Shenzhen University; Shenzhen P. R. China
| | - Liming Shen
- College of Life Sciences and Oceanography; Shenzhen University; Shenzhen P. R. China
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7
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Kono N, Arai H. Platelet-activating factor acetylhydrolases: An overview and update. Biochim Biophys Acta Mol Cell Biol Lipids 2018; 1864:922-931. [PMID: 30055287 DOI: 10.1016/j.bbalip.2018.07.006] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2018] [Revised: 07/19/2018] [Accepted: 07/23/2018] [Indexed: 01/22/2023]
Abstract
Platelet-activating factor acetylhydrolases (PAF-AHs) are unique members of the phospholipase A2 family that can hydrolyze the acetyl group of PAF, a signaling phospholipid that has roles in diverse (patho)physiological processes. Three types of PAF-AH have been identified in mammals, one plasma type and two intracellular types [PAF-AH (I) and PAF-AH (II)]. Plasma PAF-AH and PAF-AH (II) are monomeric enzymes that are structurally similar, while PAF-AH (I) is a multimeric enzyme with no homology to other PAF-AHs. PAF-AH (I) shows a strong preference for an acetyl group, whereas plasma PAF-AH and PAF-AH (II) also hydrolyze phospholipids with oxidatively modified fatty acids. Plasma PAF-AH has been implicated in several diseases including cardiovascular disease. PAF-AH (I) is required for spermatogenesis and is increasingly recognized as an oncogenic factor. PAF-AH (II) was recently shown to act as a bioactive lipid-producing enzyme in mast cells and thus could be a drug target for allergic diseases. This article is part of a Special Issue entitled Novel functions of phospholipase A2 Guest Editors: Makoto Murakami and Gerard Lambeau.
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Affiliation(s)
- Nozomu Kono
- Department of Health Chemistry, Graduate School of Pharmaceutical Sciences, The University of Tokyo, Bunkyo-ku, Tokyo 113-0033, Japan; PRIME, Japan Agency for Medical Research and Development, 1-7-1 Otemachi, Chiyodaku, Tokyo 100-0004, Japan.
| | - Hiroyuki Arai
- Department of Health Chemistry, Graduate School of Pharmaceutical Sciences, The University of Tokyo, Bunkyo-ku, Tokyo 113-0033, Japan; AMED-CREST, Japan Agency for Medical Research and Development, 1-7-1 Otemachi, Chiyodaku, Tokyo 100-0004, Japan
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8
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OLR1 scavenger receptor knockdown affects mitotic gene expression but is dispensable for oxidized phospholipid- mediated stress signaling in SZ 95 sebocytes. Mech Ageing Dev 2018; 172:35-44. [DOI: 10.1016/j.mad.2017.11.002] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2017] [Revised: 10/20/2017] [Accepted: 11/01/2017] [Indexed: 12/19/2022]
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9
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Structural and biophysical characteristics of human skin in maintaining proper epidermal barrier function. Postepy Dermatol Alergol 2016; 33:1-5. [PMID: 26985171 PMCID: PMC4793052 DOI: 10.5114/pdia.2015.48037] [Citation(s) in RCA: 112] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2014] [Accepted: 07/17/2014] [Indexed: 12/14/2022] Open
Abstract
The complex structure of human skin and its physicochemical properties turn it into an efficient outermost defence line against exogenous factors, and help maintain homeostasis of the human body. This role is played by the epidermal barrier with its major part – stratum corneum. The condition of the epidermal barrier depends on individual and environmental factors. The most important biophysical parameters characterizing the status of this barrier are the skin pH, epidermal hydration, transepidermal water loss and sebum excretion. The knowledge of biophysical skin processes may be useful for the implementation of prophylactic actions whose aim is to restore the barrier function.
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10
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Monillas ES, Caplan JL, Thévenin AF, Bahnson BJ. Oligomeric state regulated trafficking of human platelet-activating factor acetylhydrolase type-II. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2015; 1854:469-75. [PMID: 25707358 DOI: 10.1016/j.bbapap.2015.02.007] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/23/2014] [Revised: 02/06/2015] [Accepted: 02/12/2015] [Indexed: 01/19/2023]
Abstract
The intracellular enzyme platelet-activating factor acetylhydrolase type-II (PAFAH-II) hydrolyzes platelet-activating factor and oxidatively fragmented phospholipids. PAFAH-II in its resting state is mainly cytoplasmic, and it responds to oxidative stress by becoming increasingly bound to endoplasmic reticulum and Golgi membranes. Numerous studies have indicated that this enzyme is essential for protecting cells from oxidative stress induced apoptosis. However, the regulatory mechanism of the oxidative stress response by PAFAH-II has not been fully resolved. Here, changes to the oligomeric state of human PAFAH-II were investigated as a potential regulatory mechanism toward enzyme trafficking. Native PAGE analysis in vitro and photon counting histogram within live cells showed that PAFAH-II is both monomeric and dimeric. A Gly-2-Ala site-directed mutation of PAFAH-II demonstrated that the N-terminal myristoyl group is required for homodimerization. Additionally, the distribution of oligomeric PAFAH-II is distinct within the cell; homodimers of PAFAH-II were localized to the cytoplasm while monomers were associated to the membranes of the endoplasmic reticulum and Golgi. We propose that the oligomeric state of PAFAH-II drives functional protein trafficking. PAFAH-II localization to the membrane is critical for substrate acquisition and effective oxidative stress protection. It is hypothesized that the balance between monomer and dimer serves as a regulatory mechanism of a PAFAH-II oxidative stress response.
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Affiliation(s)
- Elizabeth S Monillas
- Department of Chemistry & Biochemistry, University of Delaware, Newark, DE 19716, USA
| | - Jeffrey L Caplan
- Department of Biological Sciences, University of Delaware, Newark, DE 19716, USA
| | - Anastasia F Thévenin
- Department of Chemistry & Biochemistry, University of Delaware, Newark, DE 19716, USA
| | - Brian J Bahnson
- Department of Chemistry & Biochemistry, University of Delaware, Newark, DE 19716, USA.
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Klems MM, Bahnson BJ. Trafficking and Oligomeric Regulation of Platelet-Activating Factor Acetylhydrolase Type II. PLATELET-ACTIVATING FACTOR ACETYLHYDROLASES (PAF-AH) 2015; 38:55-69. [DOI: 10.1016/bs.enz.2015.09.010] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
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12
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Karasawa K. Naturally Occurring Missense Mutation in Plasma PAF-AH Among the Japanese Population. Enzymes 2015; 38:117-43. [PMID: 26612650 DOI: 10.1016/bs.enz.2015.09.003] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
A single nucleotide polymorphism in the plasma PAF-AH enzyme, i.e., G994T, which causes the substitution of Val at amino acid 279 with Phe (V279F), has been found in the Japanese population. This enzyme preferentially degrades oxidatively modulated or truncated phospholipids; therefore, it has been suggested that this enzyme may prevent the accumulation of proinflammatory and proatherogenic oxidized phospholipids. This hypothesis is supported by the higher prevalence of the V279F mutation in patients with asthmatic and atherosclerotic diseases, as compared with healthy controls. This mutation is rare in the Caucasian population. The plasma PAF-AH mass and enzyme activity are distributed over a wide range in the plasma and they are positively correlated with low-density lipoprotein (LDL) cholesterol. However, several clinical studies in the Caucasian population have suggested that this enzyme has the opposite role. This enzyme plays an active role in the development and progression of atherosclerosis via proinflammatory and proatherogenic lysophosphatidylcholine and oxidized fatty acids produced through the oxidation of LDL by this enzyme. Thus, plasma PAF-AH is a unique enzyme with dual roles in human inflammatory diseases. In this chapter, on the basis of recent findings we describe the association between a naturally occurring missense mutation in plasma PAF-AH and human diseases especially including atherosclerosis and asthma.
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Affiliation(s)
- Ken Karasawa
- Faculty of Pharmaceutical Sciences, Teikyo University, Tokyo, Japan.
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13
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Karasawa K, Inoue K. Overview of PAF-Degrading Enzymes. PLATELET-ACTIVATING FACTOR ACETYLHYDROLASES (PAF-AH) 2015; 38:1-22. [DOI: 10.1016/bs.enz.2015.09.006] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
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14
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Kono N, Arai H. Intracellular Platelet-Activating Factor Acetylhydrolase, Type II. PLATELET-ACTIVATING FACTOR ACETYLHYDROLASES (PAF-AH) 2015; 38:43-54. [DOI: 10.1016/bs.enz.2015.09.008] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
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15
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Marathe GK, Pandit C, Lakshmikanth CL, Chaithra VH, Jacob SP, D'Souza CJM. To hydrolyze or not to hydrolyze: the dilemma of platelet-activating factor acetylhydrolase. J Lipid Res 2014; 55:1847-54. [PMID: 24859738 DOI: 10.1194/jlr.r045492] [Citation(s) in RCA: 62] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Mounting ambiguity persists around the functional role of the plasma form of platelet-activating factor acetylhydrolase (PAF-AH). Because PAF-AH hydrolyzes PAF and related oxidized phospholipids, it is widely accepted as an anti-inflammatory enzyme. On the other hand, its actions can also generate lysophosphatidylcholine (lysoPC), a component of bioactive atherogenic oxidized LDL, thus allowing the enzyme to have proinflammatory capabilities. Presence of a canonical lysoPC receptor has been seriously questioned for a multitude of reasons. Animal models of inflammation show that elevating PAF-AH levels is beneficial and not deleterious and overexpression of PAF receptor (PAF-R) also augments inflammatory responses. Further, many Asian populations have a catalytically inert PAF-AH that appears to be a severity factor in a range of inflammatory disorders. Correlation found with elevated levels of PAF-AH and CVDs has led to the design of a specific PAF-AH inhibitor, darapladib. However, in a recently concluded phase III STABILITY clinical trial, use of darapladib did not yield promising results. Presence of structurally related multiple ligands for PAF-R with varied potency, existence of multi-molecular forms of PAF-AH, broad substrate specificity of the enzyme and continuous PAF production by the so called bi-cycle of PAF makes PAF more enigmatic. This review seeks to address the above concerns.
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Affiliation(s)
- Gopal Kedihitlu Marathe
- Department of Studies in Biochemistry, University of Mysore, Manasagangothri, Mysore 570006, India
| | - Chaitanya Pandit
- Department of Studies in Biochemistry, University of Mysore, Manasagangothri, Mysore 570006, India
| | | | | | - Shancy Petsel Jacob
- Department of Studies in Biochemistry, University of Mysore, Manasagangothri, Mysore 570006, India
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Chacón-Salinas R, Chen L, Chávez-Blanco AD, Limón-Flores AY, Ma Y, Ullrich SE. An essential role for platelet-activating factor in activating mast cell migration following ultraviolet irradiation. J Leukoc Biol 2013; 95:139-48. [PMID: 24009177 DOI: 10.1189/jlb.0811409] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
The UVB (290-320 nm) radiation in sunlight is responsible for inducing skin cancer. Exposure to UV radiation is also immunosuppressive, and the systemic immune suppression induced by UV is a well-recognized risk factor for cancer induction. As UVB radiation is absorbed within the upper layers of the skin, indirect mechanisms must play a role in activating systemic immune suppression. One prominent example is mast cell migration, which from the skin to the draining LN is an essential step in the cascade of events leading to immune suppression. What triggers mast cell migration is not entirely clear. Here, we tested the hypothesis that PAF, a lipid mediator of inflammation produced by the skin in response to UV exposure, is involved. Mast cell-deficient mice (Kit(W-sh/W-sh)) are resistant to the suppressive effect of UV radiation, and reconstituting mast cell-deficient mice with normal bone marrow-derived mast cells restores susceptibility to immunosuppression. However, when mast cells from PAFR-/- mice were used, the reconstituted mice were not susceptible to the suppressive effects of UV. Furthermore, PAFR-/- mice showed impaired UV-induced mast cell migration when compared with WT mice. Finally, injecting PAF into WT mice mimicked the effect of UV irradiation and induced mast cell migration but not in PAFR-/- mice. Our findings indicate that PAFR binding induces mast cells to migrate from the skin to the LNs, where they mediate immune suppression.
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Affiliation(s)
- Rommel Chacón-Salinas
- 1.Unit 902, The University of Texas, MD Anderson Cancer Center, 1515 Holcombe Blvd., Houston, TX 77030, USA.
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Zoeller M, Stingl N, Krischke M, Fekete A, Waller F, Berger S, Mueller MJ. Lipid profiling of the Arabidopsis hypersensitive response reveals specific lipid peroxidation and fragmentation processes: biogenesis of pimelic and azelaic acid. PLANT PHYSIOLOGY 2012; 160:365-78. [PMID: 22822212 PMCID: PMC3440211 DOI: 10.1104/pp.112.202846] [Citation(s) in RCA: 137] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/02/2012] [Accepted: 07/17/2012] [Indexed: 05/19/2023]
Abstract
Lipid peroxidation (LPO) is induced by a variety of abiotic and biotic stresses. Although LPO is involved in diverse signaling processes, little is known about the oxidation mechanisms and major lipid targets. A systematic lipidomics analysis of LPO in the interaction of Arabidopsis (Arabidopsis thaliana) with Pseudomonas syringae revealed that LPO is predominantly confined to plastid lipids comprising galactolipid and triacylglyceride species and precedes programmed cell death. Singlet oxygen was identified as the major cause of lipid oxidation under basal conditions, while a 13-lipoxygenase (LOX2) and free radical-catalyzed lipid oxidation substantially contribute to the increase upon pathogen infection. Analysis of lox2 mutants revealed that LOX2 is essential for enzymatic membrane peroxidation but not for the pathogen-induced free jasmonate production. Despite massive oxidative modification of plastid lipids, levels of nonoxidized lipids dramatically increased after infection. Pathogen infection also induced an accumulation of fragmented lipids. Analysis of mutants defective in 9-lipoxygenases and LOX2 showed that galactolipid fragmentation is independent of LOXs. We provide strong in vivo evidence for a free radical-catalyzed galactolipid fragmentation mechanism responsible for the formation of the essential biotin precursor pimelic acid as well as of azelaic acid, which was previously postulated to prime the immune response of Arabidopsis. Our results suggest that azelaic acid is a general marker for LPO rather than a general immune signal. The proposed fragmentation mechanism rationalizes the pathogen-induced radical amplification and formation of electrophile signals such as phytoprostanes, malondialdehyde, and hexenal in plastids.
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Affiliation(s)
- Maria Zoeller
- Julius-von-Sachs-Institute of Biosciences, Biocenter, Pharmaceutical Biology, University of Wuerzburg, D–97082 Wuerzburg, Germany
| | - Nadja Stingl
- Julius-von-Sachs-Institute of Biosciences, Biocenter, Pharmaceutical Biology, University of Wuerzburg, D–97082 Wuerzburg, Germany
| | - Markus Krischke
- Julius-von-Sachs-Institute of Biosciences, Biocenter, Pharmaceutical Biology, University of Wuerzburg, D–97082 Wuerzburg, Germany
| | - Agnes Fekete
- Julius-von-Sachs-Institute of Biosciences, Biocenter, Pharmaceutical Biology, University of Wuerzburg, D–97082 Wuerzburg, Germany
| | - Frank Waller
- Julius-von-Sachs-Institute of Biosciences, Biocenter, Pharmaceutical Biology, University of Wuerzburg, D–97082 Wuerzburg, Germany
| | - Susanne Berger
- Julius-von-Sachs-Institute of Biosciences, Biocenter, Pharmaceutical Biology, University of Wuerzburg, D–97082 Wuerzburg, Germany
| | - Martin J. Mueller
- Julius-von-Sachs-Institute of Biosciences, Biocenter, Pharmaceutical Biology, University of Wuerzburg, D–97082 Wuerzburg, Germany
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18
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Nitoda E, Moschos MM, Mavragani CP, Koutsilieris M. Ocular actions of platelet-activating factor: clinical implications. Expert Opin Ther Targets 2012; 16:1027-39. [DOI: 10.1517/14728222.2012.712961] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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19
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McIntyre TM. Bioactive oxidatively truncated phospholipids in inflammation and apoptosis: formation, targets, and inactivation. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2012; 1818:2456-64. [PMID: 22445850 DOI: 10.1016/j.bbamem.2012.03.004] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/19/2011] [Revised: 02/23/2012] [Accepted: 03/07/2012] [Indexed: 01/12/2023]
Abstract
This report reviews structurally related phospholipid oxidation products that are biologically active where molecular mechanisms have been defined. Phospholipids containing polyunsaturated fatty acyl residues are chemically or enzymatically oxidized to phospholipid hydroperoxides, which may fragment on either side of the newly introduced peroxy function to form phospholipids with a truncated sn-2 residue. These truncated phospholipids not subject to biologic control of their production and, depending on the sn-2 residue length and structure, can stimulate the plasma membrane receptor for PAF. Alternatively, these chemically formed products can be internalized by a transport system to either stimulate the lipid activated nuclear transcription factor PPARγ or at higher levels interact with mitochondria to initiate the intrinsic apoptotic cascade. Intracellular PAF acetylhydrolases specifically hydrolyze truncated phospholipids, and not undamaged, biosynthetic phospholipids, to protect cells from oxidative death. Truncated phospholipids are also formed within cells where they couple cytokine stimulation to mitochondrial damage and apoptosis. The relevance of intracellular truncated phospholipids is shown by the complete protection from cytokine induced apoptosis by PAF acetylhydrolase expression. This protection shows truncated phospholipids are the actual effectors of cytokine mediated toxicity. This article is part of a Special Issue entitled: Oxidized phospholipids-their properties and interactions with proteins.
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20
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Thévenin AF, Monillas ES, Winget JM, Czymmek K, Bahnson BJ. Trafficking of platelet-activating factor acetylhydrolase type II in response to oxidative stress. Biochemistry 2011; 50:8417-26. [PMID: 21882811 DOI: 10.1021/bi200802w] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Platelet-activating factor acetylhydrolase type II (PAFAH-II) is an intracellular phospholipase A(2) enzyme that hydrolyzes platelet-activating factor and oxidatively fragmented phospholipids. This N-terminally myristoylated protein becomes associated with cytoplasm-facing cell membranes under oxidative stress. The structural requirements for binding of PAFAH-II to membranes in response to oxidative stress are unknown. To begin elucidating the mechanism of trafficking and stress response, we constructed a homology model of PAFAH-II. From the predicted membrane orientation of PAFAH-II, the N-terminal myristoyl group and a hydrophobic patch are hypothesized to be involved in membrane binding. Localization studies of human PAFAH-II in HEK293 cells indicated that an unmyristoylated mutant remained cytoplasmic under stressed and unstressed conditions. The myristoylated wild-type enzyme was partially localized to the cytoplasmic membranes prior to stress and became more localized to these membranes upon stress. A triple mutation of three hydrophobic patch residues of the membrane binding region likewise did not localize to membranes following stress. These results indicate that both the myristoyl group and the hydrophobic patch are essential for proper trafficking of the enzyme to the membranes following oxidative stress. Additionally, colocalization studies using organelle-specific proteins demonstrate that PAFAH-II is transported to the membranes of both the endoplasmic reticulum and Golgi apparatus.
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Affiliation(s)
- Anastasia F Thévenin
- Department of Chemistry and Biochemistry, University of Delaware, Newark, Delaware 19716, United States
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21
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Maier H, Meixner M, Hartmann D, Sandhoff R, Wang-Eckhardt L, Zöller I, Gieselmann V, Eckhardt M. Normal fur development and sebum production depends on fatty acid 2-hydroxylase expression in sebaceous glands. J Biol Chem 2011; 286:25922-34. [PMID: 21628453 DOI: 10.1074/jbc.m111.231977] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
2-Hydroxylated fatty acid (HFA)-containing sphingolipids are abundant in mammalian skin and are believed to play a role in the formation of the epidermal barrier. Fatty acid 2-hydroxylase (FA2H), required for the synthesis of 2-hydroxylated sphingolipids in various organs, is highly expressed in skin, and previous in vitro studies demonstrated its role in the synthesis of HFA sphingolipids in human keratinocytes. Unexpectedly, however, mice deficient in FA2H did not show significant changes in their epidermal HFA sphingolipids. Expression of FA2H in murine skin was restricted to the sebaceous glands, where it was required for synthesis of 2-hydroxylated glucosylceramide and a fraction of type II wax diesters. Absence of FA2H resulted in hyperproliferation of sebocytes and enlarged sebaceous glands during hair follicle morphogenesis and anagen (active growth phase) in adult mice. This was accompanied by a significant up-regulation of the epidermal growth factor receptor ligand epigen in sebocytes. Loss of FA2H significantly altered the composition and physicochemical properties of sebum, which often blocked the hair canal, apparently causing a delay in the hair fiber exit. Furthermore, mice lacking FA2H displayed a cycling alopecia with hair loss in telogen. These results underline the importance of the sebaceous glands and suggest a role of specific sebaceous gland or sebum lipids, synthesized by FA2H, in the hair follicle homeostasis.
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Affiliation(s)
- Helena Maier
- Institute of Biochemistry and Molecular Biology, Germany
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22
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Fragel-Madeira L, Meletti T, Mariante RM, Monteiro RQ, Einicker-Lamas M, Bernardo RR, Lopes AH, Linden R. Platelet activating factor blocks interkinetic nuclear migration in retinal progenitors through an arrest of the cell cycle at the S/G2 transition. PLoS One 2011; 6:e16058. [PMID: 21298035 PMCID: PMC3029264 DOI: 10.1371/journal.pone.0016058] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2010] [Accepted: 12/06/2010] [Indexed: 02/06/2023] Open
Abstract
Nuclear migration is regulated by the LIS1 protein, which is the regulatory subunit of platelet activating factor (PAF) acetyl-hydrolase, an enzyme complex that inactivates the lipid mediator PAF. Among other functions, PAF modulates cell proliferation, but its effects upon mechanisms of the cell cycle are unknown. Here we show that PAF inhibited interkinetic nuclear migration (IKNM) in retinal proliferating progenitors. The lipid did not, however, affect the velocity of nuclear migration in cells that escaped IKNM blockade. The effect depended on the PAF receptor, Erk and p38 pathways and Chk1. PAF induced no cell death, nor a reduction in nucleotide incorporation, which rules out an intra-S checkpoint. Notwithstanding, the expected increase in cyclin B1 content during G2-phase was prevented in the proliferating cells. We conclude that PAF blocks interkinetic nuclear migration in retinal progenitor cells through an unusual arrest of the cell cycle at the transition from S to G2 phases. These data suggest the operation, in the developing retina, of a checkpoint that monitors the transition from S to G2 phases of the cell cycle.
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Affiliation(s)
| | - Tamara Meletti
- Institute of Biophysics, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
| | - Rafael M. Mariante
- Institute of Biophysics, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
| | - Robson Q. Monteiro
- Institute of Medical Biochemistry, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
| | | | - Robson R. Bernardo
- Institute of Chemistry, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
| | - Angela H. Lopes
- Institute of Microbiology, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
| | - Rafael Linden
- Institute of Biophysics, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
- * E-mail:
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Abstract
Multiple factors are involved in acne pathogenesis, and sebum secretion is one of the main ones. The role sebum plays in acne development has not been completely elucidated yet; however, increasing amounts of data seem to confirm the presence of alterations in sebum from acne patients. Altered ratio between saturated and unsaturated fatty acids has been indicated as an important feature to be considered in addition to the altered amount of specific fatty acids such as linoleic acid. Furthermore, particular attention has been focused on squalene peroxide that seems to be able to induce an inflammatory response beyond cytotoxicity and comedones formation. Moreover, recent data suggest that lipid mediators are able to interfere with sebocytes differentiation and sebogenesis through the activation of pathways related to peroxisome proliferators-activated receptors. Understanding the factors and mechanisms that regulate sebum production is needed in order to identify novel therapeutic strategies for acne treatment.
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24
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Platelet activating factor stimulates arachidonic acid release in differentiated keratinocytes via arachidonyl non-selective phospholipase A2. Arch Dermatol Res 2009; 302:221-7. [PMID: 20041255 PMCID: PMC2829133 DOI: 10.1007/s00403-009-1017-8] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2009] [Revised: 12/10/2009] [Accepted: 12/14/2009] [Indexed: 11/27/2022]
Abstract
Platelet activating factor (PAF, 1-O-alkyl-2-acetyl-sn-glycero-3-phosphocholine) is known to be present in excess in psoriatic skin, but its exact role is uncertain. In the present study we demonstrate for the first time the role of group VI PLA2 in PAF-induced arachidonic acid release in highly differentiated human keratinocytes. The group IVα PLA2 also participates in the release, while secretory PLA2s play a minor role. Two anti-inflammatory synthetic fatty acids, tetradecylthioacetic acid and tetradecylselenoacetic acid, are shown to interfere with signalling events upstream of group IVα PLA2 activation. In summary, our major novel finding is the involvement of the arachidonyl non-selective group VI PLA2 in PAF-induced inflammatory responses.
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25
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McIntyre TM, Prescott SM, Stafforini DM. The emerging roles of PAF acetylhydrolase. J Lipid Res 2008; 50 Suppl:S255-9. [PMID: 18838739 DOI: 10.1194/jlr.r800024-jlr200] [Citation(s) in RCA: 109] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Platelet-activating factor (PAF), a phospholipid autacoid with potent effects throughout the innate immune system, is selectively degraded by two small families of PAF acetylhydrolases (PAF-AHs). These Ca2+-independent phospholipases A2 display remarkable specificity for the length of the sn-2 residue, but this selectivity is lost as the residue gains oxygen functions. Two of the PAF-AHs therefore are specific oxidized phospholipid phospholipases that reduce inflammation, but also remove oxidatively truncated phospholipids that induce apoptosis. The roles of these enzymes are manifold, and their separate and combined functions are now being addressed in model systems and clinical studies.
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Affiliation(s)
- Thomas M McIntyre
- Department of Cell Biology, Lerner Research Institute, Cleveland Clinic College of Medicine of Case Western Reserve University, Cleveland, OH 44195, USA.
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26
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Foulks JM, Weyrich AS, Zimmerman GA, McIntyre TM. A yeast PAF acetylhydrolase ortholog suppresses oxidative death. Free Radic Biol Med 2008; 45:434-42. [PMID: 18489912 PMCID: PMC2603548 DOI: 10.1016/j.freeradbiomed.2008.04.034] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/05/2008] [Revised: 04/17/2008] [Accepted: 04/18/2008] [Indexed: 11/26/2022]
Abstract
Phospholipids containing sn-2 polyunsaturated fatty acyl residues are primary targets of oxidizing radicals, producing proapoptotic and membrane perturbing fragmented phospholipids. The only known phospholipases that specifically select these oxidized and/or short-chained phospholipids as substrates are mammalian group VII phospholipases A2s that were purified and cloned as PAF acetylhydrolases. Platelet-activating factor (PAF) is a short-chained phospholipid, and whether these enzymes actually are PAF hydrolases or evolved as oxidized phospholipid phospholipases is unknown. The fission yeast Schizosaccharomyces pombe, which does not form or use PAF as a signaling molecule, contains an open-reading frame potentially homologous to mammalian group VII phospholipase A2s. We cloned this SPBC106.11c locus and expressed it in distantly related Saccharomyces cerevisiae that lack homologous sequences. The S. pombe locus encoded a functional phospholipase A2, now renamed plg7+, that hydrolyzed PAF and a synthetic oxidized phospholipid. Expression of human type II PAF acetylhydrolase or S. pombe Plg7p enhanced the viability of S. cerevisiae subjected to oxidative stress. We conclude that a single-celled organism with an exceedingly spare genome still expresses an unusually discriminating phospholipase A2, and that selective hydrolysis of phospholipid oxidation products is an early, and critical, way to overcome oxidative membrane damage and oxidant-induced cell death.
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Affiliation(s)
- Jason M. Foulks
- Department of Experimental Pathology, University of Utah School of Medicine, Salt Lake City, UT, 84112
- Department of Internal Medicine and Human Molecular Biology and Genetics, University of Utah School of Medicine, Salt Lake City, UT, 84112
| | - Andrew S. Weyrich
- Department of Internal Medicine and Human Molecular Biology and Genetics, University of Utah School of Medicine, Salt Lake City, UT, 84112
| | - Guy A. Zimmerman
- Department of Internal Medicine and Human Molecular Biology and Genetics, University of Utah School of Medicine, Salt Lake City, UT, 84112
| | - Thomas M. McIntyre
- Department of Cell Biology, Lerner Research Institute, Cleveland Clinic Lerner College of Medicine of CWRU, 9500 Euclid Ave, Cleveland, OH 44195
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Zouboulis CC, Baron JM, Böhm M, Kippenberger S, Kurzen H, Reichrath J, Thielitz A. Frontiers in sebaceous gland biology and pathology. Exp Dermatol 2008; 17:542-51. [PMID: 18474083 DOI: 10.1111/j.1600-0625.2008.00725.x] [Citation(s) in RCA: 130] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
The development of experimental models for the in vitro study of human sebaceous gland turned down the theory of a phylogenetic relict and led to the identification of several, unknown or disregarded functions of this organ. Such functions are the production of foetal vernix caseosa, the influence of three-dimensional organization of the skin surface lipids and the integrity of skin barrier and the influence on follicular differentiation. In addition, the sebaceous gland contributes to the transport of fat-soluble antioxidants from and to the skin surface, the natural photoprotection, the pro- and antiinflammatory skin properties and to the innate antimicrobial activity of the skin. It is mainly responsible for skin's independent endocrine function, the hormonally induced skin ageing process, the steroidogenic function of the skin as well as its thermoregulatory and repelling properties and for selective control of the hormonal and xenobiotical actions of the skin. Interestingly, sebocytes, at least in vitro, preserve characteristics of stem-like cells despite their programming for terminal differentiation. This review reports on various sebaceous gland functions, which are currently under investigation, including its role on the hypothalamus-pituitary-adrenal-like axis of the skin, the impact of acetylcholine on sebocyte biology, the activity of ectopeptidases as new targets to regulate sebocyte function, the effects of vitamin D on human sebocytes, the expression of retinoid metabolizing cytochrome P450 enzymes and the possible role of sebum as vehicle of fragrances. These multiple homeostatic functions award the sebaceous gland the role 'brain of the skin' and the most important cutaneous endocrine gland.
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28
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Kono N, Inoue T, Yoshida Y, Sato H, Matsusue T, Itabe H, Niki E, Aoki J, Arai H. Protection against oxidative stress-induced hepatic injury by intracellular type II platelet-activating factor acetylhydrolase by metabolism of oxidized phospholipids in vivo. J Biol Chem 2007; 283:1628-1636. [PMID: 18024956 DOI: 10.1074/jbc.m708622200] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Membrane phospholipids are susceptible to oxidation, which is involved in various pathological processes such as inflammation, atherogenesis, neurodegeneration, and aging. One enzyme that may help to remove oxidized phospholipids from cells is intracellular type II platelet-activating factor acetylhydrolase (PAF-AH (II)), which hydrolyzes oxidatively fragmented fatty acyl chains attached to phospholipids. Overexpression of PAF-AH (II) in cells or tissues was previously shown to suppress oxidative stress-induced cell death. In this study we investigated the functions of PAF-AH (II) by generating PAF-AH (II)-deficient (Pafah2(-/-)) mice. PAF-AH (II) was predominantly expressed in epithelial cells such as kidney proximal and distal tubules, intestinal column epithelium, and hepatocytes. Although PAF-AH activity was almost abolished in the liver and kidney of Pafah2(-/-) mice, Pafah2(-/-) mice developed normally and were phenotypically indistinguishable from wild-type mice. However, mouse embryonic fibroblasts derived from Pafah2(-/-) mice were more sensitive to tert-butylhydroperoxide treatment than those derived from wild-type mice. When carbon tetrachloride (CCl(4)) was injected into mice, Pafah2(-/-) mice showed a delay in hepatic injury recovery. Moreover, after CCl(4) administration, liver levels of the esterified form of 8-iso-PGF(2alpha), a known in vitro substrate of PAF-AH (II), were higher in Pafah2(-/-) mice than in wild-type mice. These results indicate that PAF-AH (II) is involved in the metabolism of esterified 8-isoprostaglandin F(2alpha) and protects tissue from oxidative stress-induced injury.
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Affiliation(s)
- Nozomu Kono
- Graduate School of Pharmaceutical Science, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan; PRESTO and CREST, Japan Science and Technology Agency, 4-1-8 Honcho, Kawaguchi-shi, Saitama 332-0012, Japan
| | - Takao Inoue
- Graduate School of Pharmaceutical Science, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan; PRESTO and CREST, Japan Science and Technology Agency, 4-1-8 Honcho, Kawaguchi-shi, Saitama 332-0012, Japan
| | - Yasukazu Yoshida
- Human Stress Signal Research Center, National Institute of Advanced Industrial Science and Technology, 1-8-31, Midorikawa, Ikeda, Osaka, 563-8577, Japan
| | - Hiroyuki Sato
- Pharmaceutical Research Center, Mochida Pharmaceutical Co., Ltd., 722 Uenohara, Jimba, Gotenba, Shizuoka, 412-8524, Japan
| | - Tomokazu Matsusue
- Pharmaceutical Research Center, Mochida Pharmaceutical Co., Ltd., 722 Uenohara, Jimba, Gotenba, Shizuoka, 412-8524, Japan
| | - Hiroyuki Itabe
- Department of Biological Chemistry, School of Pharmaceutical Sciences, Showa University, 1-5-8 Hatanodai, Shinagawa-ku, Tokyo 142-8555, Japan
| | - Etsuo Niki
- Human Stress Signal Research Center, National Institute of Advanced Industrial Science and Technology, 1-8-31, Midorikawa, Ikeda, Osaka, 563-8577, Japan
| | - Junken Aoki
- Graduate School of Pharmaceutical Science, Tohoku University, 6-3 Aoba, Aramaki-aza, Aoba-ku, Sendai 980-8578, Japan
| | - Hiroyuki Arai
- Graduate School of Pharmaceutical Science, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan; PRESTO and CREST, Japan Science and Technology Agency, 4-1-8 Honcho, Kawaguchi-shi, Saitama 332-0012, Japan.
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Chen R, Yang L, McIntyre TM. Cytotoxic phospholipid oxidation products. Cell death from mitochondrial damage and the intrinsic caspase cascade. J Biol Chem 2007; 282:24842-50. [PMID: 17597068 PMCID: PMC2701377 DOI: 10.1074/jbc.m702865200] [Citation(s) in RCA: 72] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Phospholipid oxidation products accumulate in the necrotic core of atherosclerotic lesions, in apoptotic cells, and circulate in oxidized low density lipoprotein. Phospholipid oxidation generates toxic products, but little is known about which specific products are cytotoxic, their receptors, or the mechanism(s) that induces cell death. We find the most common phospholipid oxidation product of oxidized low density lipoprotein, phosphatidylcholine with esterified sn-2-azelaic acid, induced apoptosis at low micromolar concentrations. The synthetic ether phospholipid hexadecyl azelaoyl phosphatidylcholine (HAzPC) was rapidly internalized, and overexpression of PLA2g7 (PAF acetylhydrolase) that specifically hydrolyzes such oxidized phospholipids suppressed apoptosis. Internalized HAzPC associated with mitochondria, and cytochrome c, and apoptosis-inducing factor escaped from mitochondria to the cytoplasm and nucleus, respectively, in cells exposed to HAzPC. Isolated mitochondria exposed to HAzPC rapidly swelled and released cytochrome c and apoptosis-inducing factor. Other phospholipid oxidation products induced swelling, but HAzPC was the most effective and was twice as effective as its diacyl homolog. Cytoplasmic cytochrome c completes the apoptosome, and activated caspase 9 and 3 were present in cells exposed to HAzPC. Irreversible inhibition of caspase 9 blocked downstream caspase 3 activation and prevented apoptosis. Mitochondrial damage initiated this apoptotic cascade, because overexpression of Bcl-X(L), an anti-apoptotic protein localized to mitochondria, blocked cytochrome c escape and apoptosis. Thus, exogenous phospholipid oxidation products target intracellular mitochondria to activate the intrinsic apoptotic cascade.
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Affiliation(s)
- Rui Chen
- Department of Cell Biology, Cleveland Clinic, Cleveland, Ohio 44195, USA
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30
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Wolf P, Nghiem DX, Walterscheid JP, Byrne S, Matsumura Y, Matsumura Y, Bucana C, Ananthaswamy HN, Ullrich SE. Platelet-activating factor is crucial in psoralen and ultraviolet A-induced immune suppression, inflammation, and apoptosis. THE AMERICAN JOURNAL OF PATHOLOGY 2006; 169:795-805. [PMID: 16936256 PMCID: PMC1579250 DOI: 10.2353/ajpath.2006.060079] [Citation(s) in RCA: 70] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Psoralen plus UVA (PUVA) is used as a very effective treatment modality for various diseases, including psoriasis and cutaneous T-cell lymphoma. PUVA-induced immune suppression and/or apoptosis are thought to be responsible for the therapeutic action. However, the molecular mechanisms by which PUVA acts are not well understood. We have previously identified platelet-activating factor (PAF), a potent phospholipid mediator, as a crucial substance triggering ultraviolet B radiation-induced immune suppression. In this study, we used PAF receptor knockout mice, a selective PAF receptor antagonist, a COX-2 inhibitor (presumably blocking downstream effects of PAF), and PAF-like molecules to test the role of PAF receptor binding in PUVA treatment. We found that activation of the PAF pathway is crucial for PUVA-induced immune suppression (as measured by suppression of delayed type hypersensitivity to Candida albicans) and that it plays a role in skin inflammation and apoptosis. Downstream of PAF, interleukin-10 was involved in PUVA-induced immune suppression but not inflammation. Better understanding of PUVA's mechanisms may offer the opportunity to dissect the therapeutic from the detrimental (ie, carcinogenic) effects and/or to develop new drugs (eg, using the PAF pathway) that act like PUVA but have fewer side effects.
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MESH Headings
- Animals
- Apoptosis/drug effects
- Apoptosis/radiation effects
- Candida albicans/immunology
- Candidiasis/drug therapy
- Candidiasis/immunology
- Candidiasis/pathology
- Combined Modality Therapy/methods
- Female
- Ficusin/pharmacology
- Humans
- Hypersensitivity, Delayed/drug therapy
- Hypersensitivity, Delayed/immunology
- Hypersensitivity, Delayed/pathology
- Immune Tolerance/drug effects
- Immune Tolerance/immunology
- Immune Tolerance/radiation effects
- Immunosuppression Therapy/methods
- Inflammation/drug therapy
- Inflammation/immunology
- Inflammation/pathology
- Interleukin-10/immunology
- Lymphoma, T-Cell, Cutaneous/drug therapy
- Lymphoma, T-Cell, Cutaneous/immunology
- Lymphoma, T-Cell, Cutaneous/pathology
- Male
- Mice
- Mice, Knockout
- PUVA Therapy/adverse effects
- PUVA Therapy/methods
- Platelet Activating Factor/immunology
- Platelet Membrane Glycoproteins/deficiency
- Platelet Membrane Glycoproteins/immunology
- Psoriasis/drug therapy
- Psoriasis/immunology
- Psoriasis/pathology
- Receptors, G-Protein-Coupled/deficiency
- Receptors, G-Protein-Coupled/immunology
- Signal Transduction/drug effects
- Signal Transduction/immunology
- Signal Transduction/radiation effects
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Affiliation(s)
- Peter Wolf
- Research Unit for Photodermatology, Department of Dermatology, Medical University Graz, Auenbrugger Platz 8, A-8036 Graz, Austria.
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31
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Zhang Q, Seltmann H, Zouboulis CC, Travers JB. Activation of platelet-activating factor receptor in SZ95 sebocytes results in inflammatory cytokine and prostaglandin E2production. Exp Dermatol 2006; 15:769-74. [PMID: 16984258 DOI: 10.1111/j.1600-0625.2006.00458.x] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Platelet-activating factor (PAF) is a group of phosphocholines with various biological effects mediated by the PAF receptor (PAF-R). Activation of the epidermal PAF-R induces the expression of inflammatory mediators, including cyclooxygenase-2 (COX-2) and prostaglandin E(2) (PGE(2)). The upregulation of COX-2 expression has been shown to be involved in sebocyte proliferation, sebaceous gland inflammation and carcinogenesis. The present study was designed to investigate whether PAF-R activation could induce the expression of COX-2 and production of PGE(2), as well as secretion of the inflammatory cytokine, interleukin-8 (IL-8), in the immortalized sebaceous gland cell line SZ95. Using calcium mobilization studies, we first confirmed that PAF can signal through PAF-R in SZ95 sebocytes. We then found that the production of IL-8 was induced following treatment with PAF-R agonist, however blocked by a specific PAF-R antagonist. Induction of COX-2 expression and increased PGE(2) production were observed in SZ95 sebocytes after PAF-R activation. Finally, it was demonstrated that the production of PGE(2), induced by PAF-R activation and mediated by COX-2 expression, was blocked following PAF-R antagonism in SZ95 sebocytes. These studies suggest that SZ95 sebocytes express functional PAF-Rs and PAF-Rs are involved in regulating the expression of inflammatory mediators, including COX-2, PGE(2) and IL-8.
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Affiliation(s)
- Qiwei Zhang
- Department of Dermatology, Indiana University School of Medicine, Indianapolis, IN 46202, USA
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32
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Zhang Q, Seltmann H, Zouboulis CC, Travers JB. Activation of platelet-activating factor receptor in SZ95 sebocytes results in inflammatory cytokine and prostaglandin E2 production. Exp Dermatol 2006. [DOI: 10.1111/j.0906-6705.2006.00458.x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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33
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Selleri S, Seltmann H, Gariboldi S, Shirai YF, Balsari A, Zouboulis CC, Rumio C. Doxorubicin-Induced Alopecia Is Associated with Sebaceous Gland Degeneration. J Invest Dermatol 2006; 126:711-20. [PMID: 16470179 DOI: 10.1038/sj.jid.5700175] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Alopecia, accompanied by skin dryness, is one of the distressing side effects often occurring in chemotherapy-treated cancer patients. Little is known of the effects of chemotherapy on sebaceous glands, despite their importance in hair follicle homeostasis. This study investigates sebaceous gland morphology and the response of SZ95 sebaceous gland cell line to doxorubicin (DXR) treatment. The morphology of sebaceous glands during intraperitoneal DXR treatment was investigated by optical and electron microscopy in a 7-day-old rat model and further confirmed in an adult mouse model. Moreover, in vitro studies using the SZ95 sebaceous gland cell line were performed to assess the response of sebocytes to DXR in terms of cell proliferation, apoptosis, and necrosis. DXR treatment induced sebaceous gland regression and occasionally caused their complete disappearance. This observed damage and disappearance preceded DXR-induced hair loss. In vitro experiments using the SZ95 sebaceous gland cell line indicated that DXR treatment induced a differentiation process leading to premature sebocytes apoptosis. Owing to the importance of the sebaceous gland in hair follicle homeostasis, DXR-induced involution of this gland might be related to subsequent hair loss.
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Affiliation(s)
- Silvia Selleri
- Department of Human Morphology, Università degli Studi di Milano, Milano, Italy
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34
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Bonin F, Ryan SD, Migahed L, Mo F, Lallier J, Franks DJ, Arai H, Bennett SAL. Anti-apoptotic Actions of the Platelet-activating Factor Acetylhydrolase I α2 Catalytic Subunit. J Biol Chem 2004; 279:52425-36. [PMID: 15456758 DOI: 10.1074/jbc.m410967200] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Platelet-activating factor (PAF) is an important mediator of cell loss following diverse pathophysiological challenges, but the manner in which PAF transduces death is not clear. Both PAF receptor-dependent and -independent pathways are implicated. In this study, we show that extracellular PAF can be internalized through PAF receptor-independent mechanisms and can initiate caspase-3-dependent apoptosis when cytosolic concentrations are elevated by approximately 15 pM/cell for 60 min. Reducing cytosolic PAF to less than 10 pM/cell terminates apoptotic signaling. By pharmacological inhibition of PAF acetylhydrolase I and II (PAF-AH) activity and down-regulation of PAF-AH I catalytic subunits by RNA interference, we show that the PAF receptor-independent death pathway is regulated by PAF-AH I and, to a lesser extent, by PAF-AH II. Moreover, the anti-apoptotic actions of PAF-AH I are subunit-specific. PAF-AH I alpha1 regulates intracellular PAF concentrations under normal physiological conditions, but expression is not sufficient to reduce an acute rise in intracellular PAF levels. PAF-AH I alpha2 expression is induced when cells are deprived of serum or exposed to apoptogenic PAF concentrations limiting the duration of pathological cytosolic PAF accumulation. To block PAF receptor-independent death pathway, we screened a panel of PAF antagonists (CV-3988, CV-6209, BN 52021, and FR 49175). BN 52021 and FR 49175 accelerated PAF hydrolysis and inhibited PAF-mediated caspase 3 activation. Both antagonists act indirectly to promote PAF-AH I alpha2 homodimer activity by reducing PAF-AH I alpha1 expression. These findings identify PAF-AH I alpha2 as a potent anti-apoptotic protein and describe a new means of pharmacologically targeting PAF-AH I to inhibit PAF-mediated cell death.
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Affiliation(s)
- Fanny Bonin
- Neural Regeneration Laboratory, Department of Biochemistry, Microbiology, and Immunology, University of Ottawa, Ottawa, Ontario K1H 8M5, Canada
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35
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Abstract
The paradox of aerobic life, or the 'Oxygen Paradox', is that animals and plants cannot exist without oxygen, yet oxygen is inherently dangerous to their existence. The reductive environment of cells provides ample opportunities for oxygen to undergo unscheduled reduction events, yielding free radicals that catalyze lipid peroxidation. Oxidized lipids are constitutively present in higher organisms and, notably, their levels increase in response to a variety of stresses. Recent results suggest that products of non-enzymatic lipid peroxidation pathways, such as the isoprostanes/phytoprostanes in animals and plants, might have an evolutionarily ancient function in host defense.
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Affiliation(s)
- Martin J Mueller
- Julius-von-Sachs-Institut of Biosciences, Pharmaceutical Biology, University of Wuerzburg, Julius-von-Sachs-Platz 2, 97082 Wuerzburg, Germany.
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36
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Huang Z, Senoh Y, Katoh S, Miwa N. Preventive effects of a water-soluble derivative of chroman moiety of vitamin E on lipid hydroperoxide-induced cell injuries and DNA cleavages through repressions of oxidative stress in the cytoplasm of human keratinocytes. J Cell Biochem 2004; 92:425-35. [PMID: 15156555 DOI: 10.1002/jcb.20081] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
ChrCrx (6-hydroxy-2, 5, 7, 8-tetramethyl-chroman-2-carboxylic acid) is a water-soluble analog in which 4', 8', 12'-trimethyltridecyl chain is deleted from an alpha-tocopherol molecule known as a hydrophobic antioxidant. Cell viability of human skin epidermal keratinocytes HaCaT was lowered by treatment with tert-butylhydroperoxide (t-BuOOH) of 50 microM for 48 h, designated as a subacute cytotoxicity, which was prevented by previous administration with ChrCrx in a dose-dependent manner as estimated by mitochondrial function-based WST-1 assay and cell morphological microscopy. In contrast an acute cytotoxicity due to treatment with t-BuOOH as dense as 200 microM for a period as short as 2 h could be also prevented with ChrCrx that was administered before and after, but was eliminated during, treatment with t-BuOOH. In contrast alpha-tocopherol was not cytoprotective against t-BuOOH. DNA strand cleavages were induced with t-BuOOH in the keratinocytes, and could be prevented by ChrCrx more effectively than alpha-tocopherol as assayed by TUNEL stain. The intracellular reactive oxygen species (ROS) was accumulated in a manner dependent on periods of t-BuOOH treatment in the cytoplasm more abundantly rather than the nucleus of keratinocytes, and was markedly diminished by ChrCrx as shown by fluorography using the redox indicator dye. Thus t-BuOOH-induced cell injuries and DNA cleavages of the keratinocytes can be prevented at least in part through efficient diminishment of ROS generated in the cytoplasm, to which the preferred distribution of ChrCrx may be advantageous over to the nucleus or membrane owing to its molecular hydrophilicity relative to alpha-tocopherol.
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Affiliation(s)
- Zhe Huang
- Department of BioTechnology, Hiroshima Prefectural University School of BioSciences, Nanatsuka, Shobara, Hiroshima, Japan
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37
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38
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Travers JB, Leung DYM, Johnson C, Schlievert P, Marques M, Cosgrove J, Clay KL. Augmentation of staphylococcal alpha-toxin signaling by the epidermal platelet-activating factor receptor. J Invest Dermatol 2003; 120:789-94. [PMID: 12713583 DOI: 10.1046/j.1523-1747.2003.12149.x] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Staphylococcal alpha-toxin is a cytolytic toxin secreted by many strains of Staphylococcus aureus that has proinflammatory and cytotoxic effects on human keratinocytes. alpha-toxin exerts its effects by forming a transmembrane pore that behaves like an ionophore for ions such as calcium. Because cellular membrane disruption with resultant intracellular calcium mobilization is a potent stimulus for the synthesis for the lipid mediator platelet-activating factor, the ability of alpha-toxin to induce platelet-activating factor production was assessed, and whether the epidermal platelet-activating factor receptor could augment toxin-induced signaling in epithelial cells examined. Treatment of the human keratinocyte-derived cell line HaCaT with alpha-toxin resulted in significant levels of platelet-activating factor, which were approximately 50% of the levels induced by calcium ionophore A23187. alpha-toxin also stimulated arachidonic acid release in HaCaT keratinocytes. Pretreatment of HaCaT cells with platelet-activating factor receptor antagonists, or overexpression of the platelet-activating factor metabolizing enzyme acetylhydrolase II blunted alpha-toxin-induced arachidonic acid release by approximately one-third, suggesting a role for toxin-produced platelet-activating factor in this process. Finally, retroviral-mediated expression of the platelet-activating factor receptor into the platelet-activating factor receptor-negative epithelial cell line KB resulted in an augmentation of alpha-toxin-mediated intracellular calcium mobilization and arachidonic acid release. These studies suggest that alpha-toxin-mediated signaling can be augmented via the epidermal platelet-activating factor receptor.
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Affiliation(s)
- Jeffrey B Travers
- Department of Dermatology, Indiana University School of Medicine, Indianapolis, Indiana 46202, USA.
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