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Nakamizo S, Honda T, Sato T, Al Mamun M, Chow Z, Duan K, Lum J, Tan KJ, Tomari K, Sato R, Kitoh A, Tay ASL, Common JEA, Guan NL, Setou M, Ginhoux F, Kabashima K. High-fat diet induces a predisposition to follicular hyperkeratosis and neutrophilic folliculitis in mice. J Allergy Clin Immunol 2021; 148:473-485.e10. [PMID: 33713763 DOI: 10.1016/j.jaci.2021.02.032] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2020] [Revised: 02/23/2021] [Accepted: 02/26/2021] [Indexed: 01/22/2023]
Abstract
BACKGROUND Neutrophilic folliculitis is an inflammatory condition of hair follicles. In some neutrophilic folliculitis, such as in patients with acne and hidradenitis suppurativa, follicular hyperkeratosis is also observed. Neutrophilic folliculitis is often induced and/or exacerbated by a high-fat diet (HFD). However, the molecular mechanisms by which an HFD affects neutrophilic folliculitis are not fully understood. OBJECTIVE Our aim was to elucidate how an HFD promotes the development of neutrophilic folliculitis. METHODS Mice were fed an HFD, and their skin was subjected to histologic, RNA sequencing, and imaging mass spectrometry analyses. To examine the effect of an HFD on neutrophil accumulation around the hair follicles, phorbol 12-myristate 13-acetate (PMA) was used as an irritant to the skin. RESULTS Histologic analysis revealed follicular hyperkeratosis in the skin of HFD-fed mice. RNA sequencing analysis showed that genes related to keratinization, especially in upper hair follicular keratinocytes, were significantly upregulated in HFD-fed mice. Application of PMA to the skin induced neutrophilic folliculitis in HFD-fed mice but not in mice fed a normal diet. Accumulation of neutrophils in the skin and around hair follicles was dependent on CXCR2 signaling, and CXCL1 (a CXCR2 ligand) was produced mainly by hair follicular keratinocytes. Imaging mass spectrometry analysis revealed an increase in fatty acids in the skin of HFD-fed mice. Application of these fatty acids to the skin induced follicular hyperkeratosis and caused PMA-induced neutrophilic folliculitis even in mice fed a normal diet. CONCLUSION An HFD can facilitate the development of neutrophilic folliculitis with the induction of hyperkeratosis of hair follicles and increased neutrophil infiltration around the hair follicles via CXCR2 signaling.
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Affiliation(s)
- Satoshi Nakamizo
- Singapore Immunology Network, Agency for Science, Technology and Research, Biopolis, Singapore; Skin Research Institute of Singapore, Agency for Science, Technology and Research, Biopolis, Singapore; Department of Dermatology, Kyoto University Graduate School of Medicine, Kyoto, Japan
| | - Tetsuya Honda
- Department of Dermatology, Kyoto University Graduate School of Medicine, Kyoto, Japan; Department of Dermatology, School of Medicine, Hamamatsu University, Hamamatsu, Shizuoka, Japan.
| | - Tomohito Sato
- Department of Cellular and Molecular Anatomy, Hamamatsu University School of Medicine, Hamamatsu, Japan
| | - Md Al Mamun
- Department of Cellular and Molecular Anatomy, Hamamatsu University School of Medicine, Hamamatsu, Japan
| | - Zachary Chow
- Skin Research Institute of Singapore, Agency for Science, Technology and Research, Biopolis, Singapore
| | - Kaibo Duan
- Singapore Immunology Network, Agency for Science, Technology and Research, Biopolis, Singapore
| | - Josephine Lum
- Singapore Immunology Network, Agency for Science, Technology and Research, Biopolis, Singapore
| | - Kahbing Jasmine Tan
- Singapore Immunology Network, Agency for Science, Technology and Research, Biopolis, Singapore; Skin Research Institute of Singapore, Agency for Science, Technology and Research, Biopolis, Singapore
| | - Kaori Tomari
- Department of Dermatology, Kyoto University Graduate School of Medicine, Kyoto, Japan
| | - Reiko Sato
- Singapore Immunology Network, Agency for Science, Technology and Research, Biopolis, Singapore; Department of Dermatology, Kyoto University Graduate School of Medicine, Kyoto, Japan
| | - Akihiko Kitoh
- Department of Dermatology, Kyoto University Graduate School of Medicine, Kyoto, Japan
| | - Angeline S L Tay
- Skin Research Institute of Singapore, Agency for Science, Technology and Research, Biopolis, Singapore
| | - John E A Common
- Skin Research Institute of Singapore, Agency for Science, Technology and Research, Biopolis, Singapore
| | - Ng Lai Guan
- Singapore Immunology Network, Agency for Science, Technology and Research, Biopolis, Singapore
| | - Mitsutoshi Setou
- Department of Cellular and Molecular Anatomy, Hamamatsu University School of Medicine, Hamamatsu, Japan
| | - Florent Ginhoux
- Singapore Immunology Network, Agency for Science, Technology and Research, Biopolis, Singapore; Skin Research Institute of Singapore, Agency for Science, Technology and Research, Biopolis, Singapore.
| | - Kenji Kabashima
- Singapore Immunology Network, Agency for Science, Technology and Research, Biopolis, Singapore; Skin Research Institute of Singapore, Agency for Science, Technology and Research, Biopolis, Singapore; Department of Dermatology, Kyoto University Graduate School of Medicine, Kyoto, Japan.
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2
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Gao QS, Xuan MF, Luo ZB, Paek HJ, Kang JD, Yin XJ. Hairless-knockout piglets generated using the clustered regularly interspaced short palindromic repeat/CRISPR-associated-9 exhibit abnormalities in the skin and thymus. Exp Anim 2019; 68:519-529. [PMID: 31308290 PMCID: PMC6842791 DOI: 10.1538/expanim.19-0018] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
The nuclear receptor corepressor Hairless (HR) interacts with nuclear receptors and
controls expression of specific target genes involved in hair morphogenesis and hair
follicle cycling. Patients with HR gene mutations exhibit atrichia, and
in rare cases, immunodeficiency. Pigs with HR gene mutations may provide
a useful model for developing therapeutic strategies because pigs are highly similar to
humans in terms of anatomy, genetics, and physiology. The present study aimed to knockout
the HR gene in pigs using the clustered regularly interspaced short
palindromic repeat (CRISPR)/CRISPR-associated-9 (Cas9) system and to investigate the
molecular and structural alterations in the skin and thymus. We introduced a biallelic
mutation into the HR gene in porcine fetal fibroblasts and generated nine
piglets via somatic cell nuclear transfer. These piglets exhibited a lack of hair on the
eyelids, abnormalities in the thymus and peripheral blood, and altered expression of
several signaling factors regulated by HR. Our results indicate that introduction of the
biallelic mutation successfully knocked out the HR gene, resulting in
several molecular and structural changes in the skin and thymus. These pigs will provide a
useful model for studying human hair disorders associated with HR gene
mutations and the underlying molecular mechanisms.
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Affiliation(s)
- Qing-Shan Gao
- Department of Animal Science, Agricultural College, Yanbian University, No. 977 Gongyuan Street, Yanji City, Jilin 133002, P.R. China
| | - Mei-Fu Xuan
- Department of Animal Science, Agricultural College, Yanbian University, No. 977 Gongyuan Street, Yanji City, Jilin 133002, P.R. China.,Jilin Provincial Key Laboratory of Transgenic Animal and Embryo Engineering, Yanbian University, No. 977 Gongyuan Street, Yanji City, Jilin 133002, P.R. China
| | - Zhao-Bo Luo
- Department of Animal Science, Agricultural College, Yanbian University, No. 977 Gongyuan Street, Yanji City, Jilin 133002, P.R. China.,Jilin Provincial Key Laboratory of Transgenic Animal and Embryo Engineering, Yanbian University, No. 977 Gongyuan Street, Yanji City, Jilin 133002, P.R. China
| | - Hyo-Jin Paek
- Jilin Provincial Key Laboratory of Transgenic Animal and Embryo Engineering, Yanbian University, No. 977 Gongyuan Street, Yanji City, Jilin 133002, P.R. China
| | - Jin-Dan Kang
- Department of Animal Science, Agricultural College, Yanbian University, No. 977 Gongyuan Street, Yanji City, Jilin 133002, P.R. China.,Jilin Provincial Key Laboratory of Transgenic Animal and Embryo Engineering, Yanbian University, No. 977 Gongyuan Street, Yanji City, Jilin 133002, P.R. China
| | - Xi-Jun Yin
- Department of Animal Science, Agricultural College, Yanbian University, No. 977 Gongyuan Street, Yanji City, Jilin 133002, P.R. China.,Jilin Provincial Key Laboratory of Transgenic Animal and Embryo Engineering, Yanbian University, No. 977 Gongyuan Street, Yanji City, Jilin 133002, P.R. China
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3
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Brook L, Whitfield GK, Hsieh D, Bither RD, Hsieh JC. The Mammalian Hairless Protein as a DNA Binding Phosphoprotein. J Cell Biochem 2016; 118:341-350. [PMID: 27355563 DOI: 10.1002/jcb.25641] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2016] [Accepted: 06/28/2016] [Indexed: 11/08/2022]
Abstract
The mammalian hairless (Hr) protein plays critical roles in skin and brain tissues, but how it interacts with DNA and partner protein is only now being defined. Our initial tests of four consensus response elements, revealed that rat Hr can specifically bind to a consensus p53 response element (p53RE), 5'-AGACATGCCTAGACATGCCT-3', but not to response elements for NF-κB, TCF4 or Sp1. We then employed ChIP assays which verified that human HR binds to a p53RE of the GADD45A gene in both HEK293 (embryonic kidney) and U87 (glioblastoma) cells. Further, HR was shown to interact directly with the p53 protein in a co-immunoprecipitation assay. Cotransfections with p53RE reporter gene constructs revealed that rat Hr can boost p53-mediated transactivation of a reporter gene linked to the GADD45A p53RE, but blunts p53-mediated transactivation when the reporter gene is linked to a p21 promoter fragment containing a p53RE, with implications for the regulation of these two cell cycle control genes. Finally, our investigations of HR phosphorylation revealed that rat Hr is a substrate for PKC, but not PKA, and that human HR is phosphorylated in intact U87 cells at Ser-416, located in a highly conserved region which partially fulfills the criteria of a PKC site. We propose that mammalian Hr is a phosphoprotein which can exert cross-talk with the p53 pathway with important implications for the regulation of cell proliferation and differentiation in tissues such as skin and brain where Hr is highly expressed. J. Cell. Biochem. 118: 341-350, 2017. © 2016 Wiley Periodicals, Inc.
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Affiliation(s)
- Lemlem Brook
- Department of Basic Medical Sciences, College of Medicine-Phoenix, University of Arizona, Phoenix, Arizona
| | - G Kerr Whitfield
- Department of Basic Medical Sciences, College of Medicine-Phoenix, University of Arizona, Phoenix, Arizona
| | - David Hsieh
- Mount Auburn Hospital, 330 Mt Auburn St, Cambridge, Massachusetts
| | - Ryan D Bither
- Department of Basic Medical Sciences, College of Medicine-Phoenix, University of Arizona, Phoenix, Arizona
| | - Jui-Cheng Hsieh
- Department of Basic Medical Sciences, College of Medicine-Phoenix, University of Arizona, Phoenix, Arizona
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4
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Kruglikov IL, Scherer PE. Skin aging: are adipocytes the next target? Aging (Albany NY) 2016; 8:1457-69. [PMID: 27434510 PMCID: PMC4993342 DOI: 10.18632/aging.100999] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2016] [Accepted: 07/07/2016] [Indexed: 01/09/2023]
Abstract
Dermal white adipose tissue (dWAT) is increasingly appreciated as a special fat depot. The adipocytes in this depot exert a variety of unique effects on their surrounding cells and can undergo massive phenotypic changes. Significant modulation of dWAT content can be observed both in intrinsically and extrinsically aged skin. Specifically, skin that has been chronically photo-damaged displays a reduction of the dWAT volume, caused by the replacement of adipocytes by fibrotic structures. This is likely to be caused by the recently uncovered process described as "adipocyte-myofibroblast transition" (AMT). In addition, contributions of dermal adipocytes to the skin aging processes are also indirectly supported by spatial correlations between the prevalence of hypertrophic scarring and the appearance of signs of skin aging in different ethnic groups. These observations could elevate dermal adipocytes to prime targets in strategies aimed at counteracting skin aging.
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Affiliation(s)
| | - Philipp E. Scherer
- Touchstone Diabetes Center, Departments of Internal Medicine and Cell Biology, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
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5
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Liu Y, Sundberg JP, Das S, Carpenter D, Cain KT, Michaud EJ, Voy BH. Molecular basis for hair loss in mice carrying a novel nonsense mutation (Hrrh-R ) in the hairless gene (Hr). Vet Pathol 2010; 47:167-76. [PMID: 20080498 DOI: 10.1177/0300985809352970] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Animal models carrying mutations in the hairless (Hr) gene provide a rich resource for study of hair follicle biology. A spontaneous mouse mutant with a phenotype strikingly similar to rhino mutants of Hr arose spontaneously in the mouse facility at Oak Ridge National Laboratory. Sequence analysis of Hr in these mutants uncovered a nonsense mutation in exon 12, designated as Hr(rh-R) (rhino, Oak Ridge). The mutation led to significant reduction in Hr mRNA levels, predicted to be due to nonsense-mediated decay. Histological analysis indicated dilated hair follicle infundibula at 14 days of age that rapidly became filled with cornified material. Microarray analyses revealed that expression levels of many genes involved in keratinocyte differentiation, epidermal regeneration, and wound healing were significantly upregulated before morphological detection of the phenotype, suggesting their role in onset of the Hr(rh-R) phenotype. Identification of this new Hr allele and the underlying molecular alterations allows further understanding of the role of Hr in hair follicle biology.
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Affiliation(s)
- Y Liu
- Life Sciences Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831-6445, USA.
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6
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Brancaz-Bouvier MV, Folco EJG, Salameire D, Romero Y, Iratni R, Nonchev S. The "bald Mill Hill" mutation in the mouse is associated with an abnormal, mislocalized HR bmh protein. J Invest Dermatol 2007; 128:311-21. [PMID: 17657241 DOI: 10.1038/sj.jid.5700998] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
We have previously identified a mutation in the mouse hairless locus-hairless rhino bald Mill Hill (Hr(rhbmh)). The genetic alteration in these mice consists in a large 296 bp deletion at the 3' part of the hairless gene (ID:MGI:3039558; J:89321). Here, we show that this deletion removes the stop codon and creates a new reading frame at the C terminus of the hairless protein, generating a larger mutant protein harboring an additional sequence of 117 amino acids. The mutant hairless gene mRNA is expressed during the embryonic and post-natal development of the hair follicle. The mutant protein is identified in bmh mouse skin at different stages of development by a specific antibody. We demonstrate that the HR bmh protein is able to interact with the vitamin D receptor (VDR), but is not able to repress VDR-mediated transactivation. Immunofluorescence analysis reveals that HR bmh protein displays an abnormal cellular localization in transfected cell lines, as well as in the epidermis and hair follicle of bmh mutant mice. We discuss the relevance of the hairless protein mis localization in cell signalling pathways and with respect to the specific skin phenotype of mouse hairless mutants.
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7
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Abstract
The hairless gene in mammals encodes a nuclear factor that is highly expressed in skin and appears to control hair follicle integrity and cycling. In the absence of a normal and functional Hairless (Hr) protein, the hair bulb undergoes premature apoptosis during the first catagen stage of the hair cycle. The most striking effects of the mutation are loss of hair follicles and formation of epidermal utricles and dermal cysts. The hairless gene expression appears to be widespread and temporally regulated. The gene is strongly expressed in different compartments of the brain. Hairless mRNAs were detected in cartilage, gonads, thymus and colon. In addition to alopecia, hairless mice strains show subtle defects in the development and differentiation of various tissues and organs. The Hr protein is localised in cell nuclei and functions as a transcriptional regulator. Although its role has not been resolved in molecular terms, it was demonstrated that Hr is able to interact with multiple nuclear hormone receptors. Hr seems to be a part of a large multiprotein complex capable to repress transcription by its association to chromatin remodelling factors such as histone deacetylases. Recent experimental data suggest that Hr might be involved in Hox gene regulation, cell adhesion modulation and progenitor cells identity. At least in the skin, but probably in other organs, the Hr repressor seems to be responsible for the timing of epithelial cells differentiation.
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Affiliation(s)
- Stefan Nonchev
- Laboratoire de Biologie Moléculaire et Cellulaire de la Différenciation, Inserm U309, Institut Albert Bonniot, Domaine de la Merci, 38706 La Troche, France.
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8
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Gozes Y, Moayeri M, Wiggins JF, Leppla SH. Anthrax lethal toxin induces ketotifen-sensitive intradermal vascular leakage in certain inbred mice. Infect Immun 2006; 74:1266-72. [PMID: 16428776 PMCID: PMC1360369 DOI: 10.1128/iai.74.2.1266-1272.2006] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Bacillus anthracis lethal toxin (LT) is a bipartite toxin composed of protective antigen (PA) and lethal factor (LF). Injection of LT produces clinical signs characteristic of anthrax infection, including pleural edema and vascular collapse in various animal models. We utilized the classic Miles leakage assay to quantify vascular leakage in mice. LT injected intradermally induced leakage as early as 15 to 25 min in some inbred mouse strains, but not in others, whereas PA or LF individually did not induce leakage. A third component of anthrax toxin, edema factor, did not induce leakage alone or with PA. Leakage was quantified in eight mouse strains, and no correlation was found between sensitivity to intradermal leakage and sensitivity to the lethality of systemically administered LT. The leakage could be inhibited by ketotifen, an inhibitor of mast cell degranulation, but not by azelastine, a histamine receptor 1 antagonist, or by ketanserin, a serotonin 5-HT2A receptor antagonist. LT was cytotoxic to MC/9 mast cells (in vitro) by 7 h after toxin treatment but did not induce histamine release from these cells. Mast cell-deficient mice exhibited the leakage event and had no increased resistance to systemic LT. Human umbilical vein endothelial cells were resistant to LT over 12 h, with only 20% of cells succumbing by 24 h, suggesting that endothelial cell killing is not the cause of the rapid LT-mediated leakage event. We describe here a ketotifen-sensitive vascular leakage event induced by LT which is the most rapid in vivo or in vitro LT-mediated effect reported to date.
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Affiliation(s)
- Yehoshua Gozes
- Microbial Pathogenesis Section, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892, USA
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9
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Nam Y, Kim JK, Cha DS, Cho JW, Cho KH, Yoon S, Yoon JB, Oh YS, Suh JG, Han SS, Song CW, Yoon SK. A novel missense mutation in the mouse hairless gene causes irreversible hair loss: genetic and molecular analyses of Hr m1Enu. Genomics 2006; 87:520-6. [PMID: 16455232 DOI: 10.1016/j.ygeno.2005.12.005] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2005] [Revised: 12/09/2005] [Accepted: 12/12/2005] [Indexed: 11/23/2022]
Abstract
A novel autosomal recessive mutant was produced using N-ethyl-N-nitrosourea mutagenesis. The characteristics of the mutant mice included progressive irreversible hair loss within a month of birth, wrinkled skin, and long curved nails. Linkage analysis revealed that the causative gene is linked to D14Mit193 on chromosome 14. Sequence analysis of the complete cDNA of the candidate gene, hairless (Hr), identified a homozygous G-to-T transition at nucleotide 3572, leading to the substitution of glycine by tryptophan, designated Gly960Trp. This missense mutation occurs in the vicinity of repression domain 3 of the hairless protein (HR). This allele was named Hr(m1Enu). The relative amounts of Hr mRNA and HR protein determined by real-time PCR and Western blot analyses, respectively, were slightly elevated in the mutant mice. Quantitative real-time PCR analysis revealed the increased expression of Kc1 and Vdr in the mutant mice, whereas the expression of Nrs1 and Krtap16-6 was decreased. These results suggest that the Gly960Trp substitution in HR protein in Hr(m1Enu) mice may alter the function of HR as a transcriptional corepressor.
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MESH Headings
- Alleles
- Alopecia/genetics
- Amino Acid Sequence
- Animals
- Blotting, Western
- Chromosome Mapping
- Chromosomes, Mammalian
- Conserved Sequence
- Crosses, Genetic
- DNA Mutational Analysis
- DNA, Complementary/genetics
- Ethylnitrosourea/pharmacology
- Genes, Recessive
- Genetic Linkage
- Haplotypes
- Homozygote
- Mice
- Mice, Inbred C57BL
- Mice, Mutant Strains
- Molecular Sequence Data
- Mutagens/pharmacology
- Mutation, Missense
- Protein Structure, Tertiary
- RNA, Messenger/analysis
- Reverse Transcriptase Polymerase Chain Reaction
- Sequence Analysis, DNA
- Sequence Homology, Amino Acid
- Transcription Factors/genetics
- Tryptophan/metabolism
- Zinc Fingers
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Affiliation(s)
- YoonYi Nam
- Laboratory of Toxicogenomics, Korea Institute of Toxicology, Taejon 305-600, Korea
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10
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Vogt A, Hebert J, Hwang J, Lu Y, Epstein EH. Anti-rejection drug treatment increases basal cell carcinoma burden in Ptch1+/- mice. J Invest Dermatol 2005; 124:263-7. [PMID: 15654983 DOI: 10.1111/j.0022-202x.2004.23573.x] [Citation(s) in RCA: 256] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The development of extensive and severe non-melanoma skin cancer is an extremely common complication of organ transplantation and is assumed to be caused by long-term treatment with anti-rejection drugs (ARD). Despite this florid clinical problem, ARD treatments have been reported to affect experimental murine skin carcinogenesis only weakly. We report here that treatment of cesium-137-irradiated Ptch1+/- mice with immunosuppressive doses of cyclosporine A plus prednisolone for 4-1/2 mo increased basal cell carcinoma burden by 2.5-fold. Thus, these mice provide a good model for study of the effects of long-term administration of ARD on at least one type of non-melanoma skin cancer.
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Affiliation(s)
- Annika Vogt
- Department of Dermatology, University of California, San Francisco, California 94110, USA
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11
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Brancaz MV, Iratni R, Morrison A, Mancini SJC, Marche P, Sundberg J, Nonchev S. A new allele of the mouse hairless gene interferes with Hox/LacZ transgene regulation in hair follicle primordia. Exp Mol Pathol 2004; 76:173-81. [PMID: 15010296 DOI: 10.1016/j.yexmp.2003.10.003] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2003] [Indexed: 10/26/2022]
Abstract
A new autosomal recessive mouse mutation, causing loss of hair in homozygous mice 2-3 weeks after birth, arose spontaneously in a colony at the National Institute for Medical Research (NIMR), Mill Hill, London in early 1998. Complementation analysis confirmed that this mutation was an allele of the hairless gene (hr). The gene symbol hr(rhbm) (hairless-rhino-bald Mill Hill) was assigned to reflect the source of the colony. Here we show the molecular defect in these mutants, which is a substantial deletion at the 3'-end of the hairless gene. Morphological and immunological analysis of the new hairless mutation was performed at early postnatal stages. In an effort to address the molecular and cellular mechanisms of the hairless phenotype, we analysed developmental stages before the establishment of alopecia. Using a HoxLacZ reporter line of transgenic mice, epidermal placode formation was followed in embryos. Homozygous mutant embryos (hr(rhbmh)/hr(rhbmh)), containing the LacZ reporter under the control of a Hoxb4 gene enhancer, display sharp loss of LacZ staining in epidermal cells invaginating to form the embryonic hair follicle placode. In the light of targeted mutagenesis data involving a Hox gene in the hair development, we discuss the potential implication of the hr(rhbmh) locus in cascades of Hox gene regulation during embryogenesis.
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12
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Domínguez-Gerpe L, Rey-Méndez M. Evolution of the thymus size in response to physiological and random events throughout life. Microsc Res Tech 2003; 62:464-76. [PMID: 14635139 DOI: 10.1002/jemt.10408] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
During embryogenesis and in the early stages of life, the thymus is a crucial organ for the generation of the T cell repertoire. T cells are generated from hematopoietic stem cells already differentiated to precursor T cells in the bone marrow. These cells enter the thymus guided by chemotactic factors secreted by this organ. The complex maturation process takes place that ensures self-tolerance and homeostasis. Thymocytes that show autoreactivity do not leave the thymus, but rather die by apoptosis. The final percentage of mature T cells that survive to migrate from the thymus to the periphery is very low: at most 5%, under optimal conditions. The highest migration occurs in childhood and adulthood, at least in mice and humans; however, it declines throughout life and is minimal in the elderly. Under normal circumstances, the thymus commences involution soon after birth, and this involution correlates with the capacity to export mature T cells to the periphery. Hormones, cytokines, and neurotransmitters all play a role in this age-associated process, but the reasons for and mechanisms of this involution remain unknown. Apart from physiological conditions that change throughout life and govern age-related thymus evolution, random states and events provoked by intrinsic or extrinsic factors can induce either thymus involution, as in reversible transient thymic hypoplasias, or thymic hyperplasias. The age-associated involution, unlike transient involutions, follows a regular pattern for all individuals, though there are clear differences between the sexes. Nevertheless, even the age-associated involution seems to be reversible, raising the possibility of therapeutic strategies aimed at enhancing thymus function in the elderly.
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Affiliation(s)
- Lourdes Domínguez-Gerpe
- Departamento de Bioquímica y Biología Molecular, Facultad de Biología, Universidad de Santiago de Compostela, 15706 Santiago de Compostela, La Coruña, Spain.
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13
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Varas A, Sacedón R, Hernandez-López C, Jiménez E, García-Ceca J, Arias-Díaz J, Zapata AG, Vicente A. Age-dependent changes in thymic macrophages and dendritic cells. Microsc Res Tech 2003; 62:501-7. [PMID: 14635143 DOI: 10.1002/jemt.10411] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Aging is characterized by the decline and deregulation of several physiological systems, especially the immune system. The involution of the thymus gland has been identified as one of the key events that precedes the age-related decline in immune function. Whereas the decrease in thymocyte numbers and in the thymic output during thymus atrophy has been analyzed by various authors, very little information is available about the age-associated modifications in thymic macrophages and dendritic cells. Here we present evidence that these thymic stromal cell components are only slightly affected by age.
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Affiliation(s)
- Alberto Varas
- Department of Cell Biology, Faculty of Medicine, Complutense University, Madrid, Spain.
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