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Maruta H, Kittaka A. Chemical evolution for taming the 'pathogenic kinase' PAK1. Drug Discov Today 2020; 25:959-964. [PMID: 32348877 PMCID: PMC7194552 DOI: 10.1016/j.drudis.2020.03.008] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2020] [Revised: 02/17/2020] [Accepted: 03/11/2020] [Indexed: 01/14/2023]
Abstract
PAK1 is the major ‘pathogenic’ kinase. Several potent PAK1 blockers developed are introduced for treatment of a wide variety of PAK1-dependent diseases including cancers and pandemic COVID-19 infection.
To celebrate the 25th anniversary of the cloning of the first mammalian p21-activated kinases (PAKs) (RAC/CDC42-activated kinases) by Ed Manser, the first international PAK symposium was held in NYC in October 2019. Among six distinct PAKs in mammals, PAK1 is the major ‘pathogenic kinase’, the abnormal activation of which is responsible for a wide variety of diseases and disorders including cancers, ageing processes and infectious and inflammatory diseases such as pandemic coronaviral infection. Recently, for a clinical application, a few potent (highly cell-permeable and water-soluble) PAK1 blockers have been developed from natural or synthetic PAK1 blockers (triptolide, vitamin D3 and ketorolac) via a series of ‘chemical evolutions’ that boost pharmacological activities >500 times.
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Larsen BM, Cowan JE, Wang Y, Tanaka Y, Zhao Y, Voisin B, Constantinides MG, Nagao K, Belkaid Y, Awasthi P, Takahama Y, Bhandoola A. Identification of an Intronic Regulatory Element Necessary for Tissue-Specific Expression of Foxn1 in Thymic Epithelial Cells. THE JOURNAL OF IMMUNOLOGY 2019; 203:686-695. [PMID: 31243087 DOI: 10.4049/jimmunol.1801540] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/26/2018] [Accepted: 05/28/2019] [Indexed: 01/23/2023]
Abstract
The thymus is critical for the establishment of the adaptive immune system and the development of a diverse T cell repertoire. T cell development depends upon cell-cell interactions with epithelial cells in the thymus. The thymus is composed of two different types of epithelial cells: cortical and medullary epithelial cells. Both of these express and critically depend on the transcription factor Foxn1 Foxn1 is also expressed in the hair follicle, and disruption of Foxn1 function in mice results in severe thymic developmental defects and the hairless (nude) phenotype. Despite its importance, little is known about the direct regulation of Foxn1 expression. In this study, we identify a cis-regulatory element (RE) critical for expression of Foxn1 in mouse thymic epithelial cells but dispensable for expression in hair follicles. Analysis of chromatin accessibility, histone modifications, and sequence conservation identified regions within the first intron of Foxn1 that possessed the characteristics of REs. Systematic knockout of candidate regions lead us to identify a 1.6 kb region that, when deleted, results in a near total disruption of thymus development. Interestingly, Foxn1 expression and function in the hair follicle were unaffected. RNA fluorescent in situ hybridization showed a near complete loss of Foxn1 mRNA expression in the embryonic thymic bud. Our studies have identified a genomic RE with thymic-specific control of Foxn1 gene expression.
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Affiliation(s)
- Brian M Larsen
- Laboratory of Genome Integrity, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892
| | - Jennifer E Cowan
- Laboratory of Genome Integrity, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892
| | - Yueqiang Wang
- Laboratory of Genome Integrity, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892
| | - Yu Tanaka
- Experimental Immunology Branch, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892
| | - Yongge Zhao
- Laboratory of Genome Integrity, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892
| | - Benjamin Voisin
- Dermatology Branch, National Institute of Arthritis and Musculoskeletal and Skin Diseases, National Institutes of Health, Bethesda, MD 20892
| | - Michael G Constantinides
- Metaorganism Immunity Section, Laboratory of Immune System Biology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892; and
| | - Keisuke Nagao
- Dermatology Branch, National Institute of Arthritis and Musculoskeletal and Skin Diseases, National Institutes of Health, Bethesda, MD 20892
| | - Yasmine Belkaid
- Metaorganism Immunity Section, Laboratory of Immune System Biology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892; and
| | - Parirokh Awasthi
- Laboratory Animal Sciences Program, Leidos Biomedical Research Inc., Frederick National Laboratory for Cancer Research, National Institutes of Health, Frederick, MD 21701
| | - Yousuke Takahama
- Experimental Immunology Branch, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892
| | - Avinash Bhandoola
- Laboratory of Genome Integrity, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892;
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Kolb AD, Shupp AB, Mukhopadhyay D, Marini FC, Bussard KM. Osteoblasts are "educated" by crosstalk with metastatic breast cancer cells in the bone tumor microenvironment. Breast Cancer Res 2019; 21:31. [PMID: 30813947 PMCID: PMC6391840 DOI: 10.1186/s13058-019-1117-0] [Citation(s) in RCA: 49] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2018] [Accepted: 02/07/2019] [Indexed: 12/14/2022] Open
Abstract
INTRODUCTION In a cancer-free environment in the adult, the skeleton continuously undergoes remodeling. Bone-resorbing osteoclasts excavate erosion cavities, and bone-depositing osteoblasts synthesize osteoid matrix that forms new bone, with no net bone gain or loss. When metastatic breast cancer cells invade the bone, this balance is disrupted. Patients with bone metastatic breast cancer frequently suffer from osteolytic bone lesions that elicit severe bone pain and fractures. Bisphosphonate treatments are not curative. Under ideal circumstances, osteoblasts would synthesize new matrix to fill in erosion cavities caused by osteoclasts, but this is not what occurs. Our prior evidence demonstrated that osteoblasts are diverted from laying down bone matrix to producing cytokines that facilitate breast cancer cell maintenance in late-stage disease. Here, we have new evidence to suggest that there are subpopulations of osteoblasts in the tumor niche as evidenced by their protein marker expression that have distinct roles in tumor progression in the bone. METHODS Tumor-bearing tibia of mice was interrogated by immunofluorescent staining for the presence of osteoblasts and alterations in niche protein expression. De-identified tissue from patients with bone metastatic breast cancer was analyzed for osteoblast subpopulations via multi-plex immunofluorescent staining. Effects of breast cancer cells on osteoblasts were recapitulated in vitro by osteoblast exposure to breast cancer-conditioned medium. Triple-negative and estrogen receptor-positive breast cancer proliferation, cell cycle, and p21 expression were assessed upon contact with "educated" osteoblasts. RESULTS A subpopulation of osteoblasts was identified in the bone tumor microenvironment in vivo of both humans and mice with bone metastatic breast cancer that express RUNX2/OCN/OPN but is negative for IL-6 and alpha-smooth muscle actin. These tumor "educated" osteoblasts (EOs) have altered properties compared to "uneducated" osteoblasts and suppress both triple-negative and estrogen receptor-positive breast cancer cell proliferation and increase cancer cell p21 expression. EO effects on breast cancer proliferation were mediated by NOV and decorin. Importantly, the presence of EO cells in the tibia of mice bearing tumors led to increased amounts of alkaline phosphatase and suppressed the expression of inflammatory cytokines in vivo. CONCLUSIONS Our work reveals that there is a subpopulation of osteoblasts in the bone tumor microenvironment that demonstrate a functional role in retarding breast cancer cell growth.
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Affiliation(s)
- Alexus D. Kolb
- Department of Cancer Biology, Sidney Kimmel Cancer Center, Thomas Jefferson University, Philadelphia, PA USA
| | - Alison B. Shupp
- Department of Cancer Biology, Sidney Kimmel Cancer Center, Thomas Jefferson University, Philadelphia, PA USA
| | - Dimpi Mukhopadhyay
- Department of Cancer Biology, Sidney Kimmel Cancer Center, Thomas Jefferson University, Philadelphia, PA USA
| | - Frank C. Marini
- Comprehensive Cancer Center Wake Forest University and Wake Forest Institute of Regenerative Medicine, Winston-Salem, NC USA
| | - Karen M. Bussard
- Department of Cancer Biology, Sidney Kimmel Cancer Center, Thomas Jefferson University, Philadelphia, PA USA
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Yang M, Song S, Dong K, Chen X, Liu X, Rouzi M, Zhao Q, He X, Pu Y, Guan W, Ma Y, Jiang L. Skin transcriptome reveals the intrinsic molecular mechanisms underlying hair follicle cycling in Cashmere goats under natural and shortened photoperiod conditions. Sci Rep 2017; 7:13502. [PMID: 29044192 PMCID: PMC5647384 DOI: 10.1038/s41598-017-13986-w] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2017] [Accepted: 10/04/2017] [Indexed: 11/09/2022] Open
Abstract
The growth of cashmere exhibits a seasonal pattern arising from photoperiod change. However, the underlying molecular mechanism remains unclear. We profiled the skin transcriptome of six goats at seven time points during hair follicle cycling via RNA-seq. The six goats comprised three goats exposed to a natural photoperiod and three exposed to a shortened photoperiod. During hair cycle transition, 1713 genes showed differential expression, and 332 genes showed a pattern of periodic expression. Moreover, a short photoperiod induced the hair follicle to enter anagen early, and 246 genes overlapped with the periodic genes. Among these key genes, cold-shock domain containing C2 (CSDC2) was highly expressed in the epidermis and dermis of Cashmere goat skin, although its function in hair-follicle development remains unknown. CSDC2 silencing in mouse fibroblasts resulted in the decreased mRNA expression of two key hair-follicle factors, leading to reduced cell numbers and a lower cell density. Cashmere growth or molting might be controlled by a set of periodic regulatory genes. The appropriate management of short light exposure can induce hair follicles to enter full anagen early through the activation of these regulators. The CSDC2 gene is a potentially important transcription factor in the hair growth cycle.
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Affiliation(s)
- Min Yang
- State Key Laboratory of Animal Nutrition, Institute of Animal Science (IAS), Chinese Academy of Agricultural Sciences (CAAS), Beijing, 100193, China
| | - Shen Song
- State Key Laboratory of Animal Nutrition, Institute of Animal Science (IAS), Chinese Academy of Agricultural Sciences (CAAS), Beijing, 100193, China
- Department of Animal Genetics and Breeding, China Agricultural University, Beijing, 100094, China
| | - Kunzhe Dong
- State Key Laboratory of Animal Nutrition, Institute of Animal Science (IAS), Chinese Academy of Agricultural Sciences (CAAS), Beijing, 100193, China
| | - XiaoFei Chen
- State Key Laboratory of Animal Nutrition, Institute of Animal Science (IAS), Chinese Academy of Agricultural Sciences (CAAS), Beijing, 100193, China
| | - Xuexue Liu
- State Key Laboratory of Animal Nutrition, Institute of Animal Science (IAS), Chinese Academy of Agricultural Sciences (CAAS), Beijing, 100193, China
| | - Marhaba Rouzi
- State Key Laboratory of Animal Nutrition, Institute of Animal Science (IAS), Chinese Academy of Agricultural Sciences (CAAS), Beijing, 100193, China
| | - Qianjun Zhao
- State Key Laboratory of Animal Nutrition, Institute of Animal Science (IAS), Chinese Academy of Agricultural Sciences (CAAS), Beijing, 100193, China
| | - Xiaohong He
- State Key Laboratory of Animal Nutrition, Institute of Animal Science (IAS), Chinese Academy of Agricultural Sciences (CAAS), Beijing, 100193, China
| | - Yabin Pu
- State Key Laboratory of Animal Nutrition, Institute of Animal Science (IAS), Chinese Academy of Agricultural Sciences (CAAS), Beijing, 100193, China
| | - Weijun Guan
- State Key Laboratory of Animal Nutrition, Institute of Animal Science (IAS), Chinese Academy of Agricultural Sciences (CAAS), Beijing, 100193, China
| | - Yuehui Ma
- State Key Laboratory of Animal Nutrition, Institute of Animal Science (IAS), Chinese Academy of Agricultural Sciences (CAAS), Beijing, 100193, China.
| | - Lin Jiang
- State Key Laboratory of Animal Nutrition, Institute of Animal Science (IAS), Chinese Academy of Agricultural Sciences (CAAS), Beijing, 100193, China.
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Roberts NA, Adams BD, McCarthy NI, Tooze RM, Parnell SM, Anderson G, Kaech SM, Horsley V. Prdm1 Regulates Thymic Epithelial Function To Prevent Autoimmunity. JOURNAL OF IMMUNOLOGY (BALTIMORE, MD. : 1950) 2017; 199:1250-1260. [PMID: 28701508 PMCID: PMC5544928 DOI: 10.4049/jimmunol.1600941] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/03/2016] [Accepted: 06/10/2017] [Indexed: 01/10/2023]
Abstract
Autoimmunity is largely prevented by medullary thymic epithelial cells (TECs) through their expression and presentation of tissue-specific Ags to developing thymocytes, resulting in deletion of self-reactive T cells and supporting regulatory T cell development. The transcription factor Prdm1 has been implicated in autoimmune diseases in humans through genome-wide association studies and in mice using cell type-specific deletion of Prdm1 in T and dendritic cells. In this article, we demonstrate that Prdm1 functions in TECs to prevent autoimmunity in mice. Prdm1 is expressed by a subset of mouse TECs, and conditional deletion of Prdm1 in either Keratin 14- or Foxn1-expressing cells in mice resulted in multisymptom autoimmune pathology. Notably, the development of Foxp3+ regulatory T cells occurs normally in the absence of Blimp1. Importantly, nude mice developed anti-nuclear Abs when transplanted with Prdm1 null TECs, but not wild-type TECs, indicating that Prdm1 functions in TECs to regulate autoantibody production. We show that Prdm1 acts independently of Aire, a crucial transcription factor implicated in medullary TEC function. Collectively, our data highlight a previously unrecognized role for Prdm1 in regulating thymic epithelial function.
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Affiliation(s)
- Natalie A Roberts
- Department of Molecular, Cellular and Developmental Biology, Yale University, New Haven, CT 06520
- The Francis Crick Institute, London NW1 1AT, United Kingdom
| | - Brian D Adams
- The RNA Institute, University at Albany, State University of New York, Albany, NY 12222
- Investigative Medicine Program, Yale University School of Medicine, New Haven, CT 06520
| | - Nicholas I McCarthy
- School of Immunity and Infection, Medical Research Council Centre for Immune Regulation, University of Birmingham, Birmingham B15 2TT, United Kingdom
| | - Reuben M Tooze
- Section of Experimental Haematology, Leeds Institute of Molecular Medicine, University of Leeds, Leeds LS2 9JT, United Kingdom
| | - Sonia M Parnell
- School of Immunity and Infection, Medical Research Council Centre for Immune Regulation, University of Birmingham, Birmingham B15 2TT, United Kingdom
| | - Graham Anderson
- School of Immunity and Infection, Medical Research Council Centre for Immune Regulation, University of Birmingham, Birmingham B15 2TT, United Kingdom
| | - Susan M Kaech
- Department of Immunobiology, Yale University, New Haven, CT 06520; and
| | - Valerie Horsley
- Department of Molecular, Cellular and Developmental Biology, Yale University, New Haven, CT 06520;
- Department of Dermatology, Yale University, New Haven, CT 06520
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Vaidya HJ, Briones Leon A, Blackburn CC. FOXN1 in thymus organogenesis and development. Eur J Immunol 2016; 46:1826-37. [PMID: 27378598 PMCID: PMC4988515 DOI: 10.1002/eji.201545814] [Citation(s) in RCA: 67] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2016] [Revised: 06/21/2016] [Accepted: 06/29/2016] [Indexed: 01/11/2023]
Abstract
Development of the primary T-cell repertoire takes place in the thymus. The linked processes of T-cell differentiation and T-cell repertoire selection each depend on interactions between thymocytes and thymic stromal cells; in particular, with the epithelial cells of the cortical and medullary thymic compartments (cortical and medullary thymic epithelial cells; cTECs and mTECs, respectively). The importance of the thymic epithelial cell lineage in these processes was revealed in part through analysis of nude (nu/nu) mice, which are congenitally hairless and athymic. The nude phenotype results from null mutation of the forkhead transcription factor FOXN1, which has emerged as a pivotal regulator both of thymus development and homeostasis. FOXN1 has been shown to play critical roles in thymus development, function, maintenance, and even regeneration, which positions it as a master regulator of thymic epithelial cell (TEC) differentiation. In this review, we discuss current understanding of the regulation and functions of FOXN1 throughout thymus ontogeny, from the earliest stages of organogenesis through homeostasis to age-related involution, contextualising its significance through reference to other members of the wider Forkhead family.
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Affiliation(s)
- Harsh Jayesh Vaidya
- MRC Centre for Regenerative MedicineInstitute for Stem Cell ResearchSchool of Biological SciencesEdinburghUK
| | - Alberto Briones Leon
- MRC Centre for Regenerative MedicineInstitute for Stem Cell ResearchSchool of Biological SciencesEdinburghUK
| | - C. Clare Blackburn
- MRC Centre for Regenerative MedicineInstitute for Stem Cell ResearchSchool of Biological SciencesEdinburghUK
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7
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Loss of Pten Disrupts the Thymic Epithelium and Alters Thymic Function. PLoS One 2016; 11:e0149430. [PMID: 26914657 PMCID: PMC4767252 DOI: 10.1371/journal.pone.0149430] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2015] [Accepted: 01/20/2016] [Indexed: 11/19/2022] Open
Abstract
The thymus is the site of T cell development and selection. In addition to lymphocytes, the thymus is composed of several types of stromal cells that are exquisitely organized to create the appropriate environment and microenvironment to support the development and selection of maturing T cells. Thymic epithelial cells (TECs) are one of the more important cell types in the thymic stroma, and they play a critical role in selecting functional T cell clones and supporting their development. In this study, we used a mouse genetics approach to investigate the consequences of deleting the Pten tumor suppressor gene in the TEC compartment of the developing thymus. We found that PTEN deficiency in TECs results in a smaller thymus with significantly disordered architecture and histology. Accordingly, loss of PTEN function also results in decreased T cells with a shift in the distribution of T cell subtypes towards CD8+ T cells. These experiments demonstrate that PTEN is critically required for the development of a functional thymic epithelium in mice. This work may help better understand the effects that certain medical conditions or clinical interventions have upon the thymus and immune function.
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Araujo VCP, Fukutani KF, Oshiro ET, Rodrigues PO, Rizk YS, Carollo CA, Arruda CCP. Hairless mice as an experimental model of infection with Leishmania (Leishmania) amazonensis. Exp Parasitol 2015; 157:138-44. [PMID: 26234915 DOI: 10.1016/j.exppara.2015.07.010] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2014] [Revised: 06/23/2015] [Accepted: 07/30/2015] [Indexed: 12/19/2022]
Abstract
HRS/J Hairless mice have been investigated as an experimental model in cutaneous leishmaniasis induced by Leishmania (Leishmania) amazonensis. The animals were inoculated with 10(6) promastigotes into the right hind footpad and the course of infection was followed up for 30, 60 and 90 days. BALB/c mice were infected and used as control. Hairless mice were susceptible to L. (L.) amazonensis infection and a progressive increase in number of parasites and footpad thickness was detected over time. Signals of dissemination and visceralization were confirmed by the presence of parasite in the draining lymph node of lesion and spleen, at different times post infection. IL-10 gene expression evaluated by RT-PCR was significantly higher in Hairless mice at 60 days post infection, corroborating the pattern of susceptibility. These results point this inbred strain as a promising susceptible model for the study of experimental infection induced by L. (L.) amazonensis. This model would allow the use of other infection sites that minimize secondary interference and best monitoring the skin lesion, as in the case of in vivo assays of potential drugs for LT.
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Affiliation(s)
- Vanessa Carneiro Pereira Araujo
- Laboratório de Parasitologia Humana, Centro de Ciências Biológicas e da Saúde, Universidade Federal de Mato Grosso do Sul, Av. Costa e Silva, S/No, Cidade Universitária, Campo Grande, Brazil.
| | - Kiyoshi Ferreira Fukutani
- Laboratório de Imunoparasitologia, Centro de Pesquisas Gonçalo Moniz, FIOCRUZ, Salvador, Bahia, Brazil.
| | - Elisa Teruya Oshiro
- Laboratório de Parasitologia Humana, Centro de Ciências Biológicas e da Saúde, Universidade Federal de Mato Grosso do Sul, Av. Costa e Silva, S/No, Cidade Universitária, Campo Grande, Brazil.
| | - Patrik Oening Rodrigues
- Laboratório de Tecnologia Farmacêutica, Centro de Ciências Biológicas e da Saúde, Universidade Federal de Mato Grosso do Sul, Av. Costa e Silva, S/No, Cidade Universitária, Campo Grande, Brazil.
| | - Yasmin Silva Rizk
- Laboratório de Parasitologia Humana, Centro de Ciências Biológicas e da Saúde, Universidade Federal de Mato Grosso do Sul, Av. Costa e Silva, S/No, Cidade Universitária, Campo Grande, Brazil.
| | - Carlos Alexandre Carollo
- Laboratório de Produtos Naturais e Espectrometria de Massas - LaPNEM, Centro de Ciências Biológicas e da Saúde, Universidade Federal de Mato Grosso do Sul, Av. Costa e Silva, S/No, Cidade Universitária, Campo Grande, Brazil.
| | - Carla Cardozo Pinto Arruda
- Laboratório de Parasitologia Humana, Centro de Ciências Biológicas e da Saúde, Universidade Federal de Mato Grosso do Sul, Av. Costa e Silva, S/No, Cidade Universitária, Campo Grande, Brazil.
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9
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Roberts N, Horsley V. Developing stratified epithelia: lessons from the epidermis and thymus. WILEY INTERDISCIPLINARY REVIEWS-DEVELOPMENTAL BIOLOGY 2014; 3:389-402. [PMID: 25176390 DOI: 10.1002/wdev.146] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/21/2014] [Revised: 06/25/2014] [Accepted: 07/02/2014] [Indexed: 01/01/2023]
Abstract
Stratified squamous epithelial cells are found in a number of organs, including the skin epidermis and the thymus. The progenitor cells of the developing epidermis form a multi-layered epithelium and appendages, like the hair follicle, to generate an essential barrier to protect against water loss and invasion of foreign pathogens. In contrast, the thymic epithelium forms a three-dimensional mesh of keratinocytes that are essential for positive and negative selection of self-restricted T cells. While these distinct stratified epithelial tissues derive from distinct embryonic germ layers, both tissues instruct immunity, and the epithelial differentiation programs and molecular mechanisms that control their development are remarkably similar. In this review, we aim to highlight some of the similarities between the thymus and the skin epidermis and its appendages during developmental specification.
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Affiliation(s)
- Natalie Roberts
- Department of Molecular, Cell and Developmental Biology, Yale University, New Haven, CT, USA
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10
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Kushwaha R, Thodima V, Tomishima MJ, Bosl GJ, Chaganti RSK. miR-18b and miR-518b Target FOXN1 during epithelial lineage differentiation in pluripotent cells. Stem Cells Dev 2014; 23:1149-56. [PMID: 24383669 DOI: 10.1089/scd.2013.0262] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
MicroRNAs (miRNAs) regulate myriad biological processes; however, their role in cell fate choice is relatively unexplored. Pluripotent NT2/D1 embryonal carcinoma cells differentiate into an epithelial/smooth muscle phenotype when treated with bone morphogenetic protein-2 (BMP-2). To identify miRNAs involved in epithelial cell development, we performed miRNA profiling of NT2/D1 cells treated with BMP-2 at 6, 12, and 24 h, and on days 6 and 10. Integration of the miRNA profiling data with previously obtained gene expression profiling (GEP) data of NT2/D1 cells treated with BMP-2 at the same time points identified miR-18b and miR-518b as the top two miRNAs with the highest number of up-regulated predicted targets with known functions in epithelial lineage development. Silencing of miR-18b and miR-518b in NT2/D1 cells revealed several up-regulated TFs with functions in epithelial lineage development; among these, target prediction programs identified FOXN1 as the only direct target of both miRNAs. FOXN1 has previously been shown to play an important role in keratinocyte differentiation and epithelial cell proliferation. NT2/D1 and H9 human embryonic stem cells with silenced miR-18b and miR-518b showed up-regulation of FOXN1 and the epithelial markers CDH1, EPCAM, KRT19, and KRT7. A 3'UTR luciferase assay confirmed FOXN1 to be a target of the two miRNAs, and up-regulation of FOXN1 in NT2/D1 cells led to the expression of epithelial markers. Overexpression of the two miRNAs in BMP-2-treated NT2/D1 cells led to down-regulation of FOXN1 and epithelial lineage markers. These results show that miR-18b and miR-518b are upstream controllers of FOXN1-directed epithelial lineage development.
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Affiliation(s)
- Ritu Kushwaha
- 1 Cell Biology Program, Memorial Sloan-Kettering Cancer Center , New York, New York
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11
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Pan B, Liu J, Zhang Y, Sun Y, Wu Q, Zhao K, Zeng L, Xu K. Acute ablation of DP thymocytes induces up-regulation of IL-22 and Foxn1 in TECs. Clin Immunol 2014; 150:101-8. [PMID: 24333537 DOI: 10.1016/j.clim.2013.11.002] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2013] [Revised: 10/18/2013] [Accepted: 11/01/2013] [Indexed: 12/20/2022]
Abstract
Thymic epithelial cells (TECs) provide the basic architecture for the development of thymocytes. TEC is regenerative after impairment in thymus of young mice. However, how this regeneration program is governed remains unclear. Transcription factor Foxn1 is a central mediator of the differentiation and function of TEC. We examined the relation between thymic injury and Foxn1 in TEC. Total body irradiation (TBI) treatments induced up-regulation of Foxn1 in TEC, which was abolished when thymic function recovered. Specific depletion of double positive (DP) thymocytes triggered the up-regulation of Foxn1. On the other hand, extracellular IL-22 is a potential regulator of homeostasis of TEC. We demonstrated that TBI treatments also induced the up-regulation of intrathymic IL-22. Expression pattern of Foxn1 shares similar characteristics with IL-22. Furthermore, Foxn1 related genes that regulate the function of TEC were also up-regulated. Thus, our data reveal that TBI treatment triggers regeneration program of TEC.
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Affiliation(s)
- Bin Pan
- Department of Hematology, The Affiliated Hospital of Xuzhou Medical College, Xuzhou, China
| | - Jie Liu
- Department of Hematology, The Affiliated Hospital of Xuzhou Medical College, Xuzhou, China
| | - Ying Zhang
- Laboratory of Transplant Immunology, Xuzhou Medical College, Xuzhou, China
| | - Yuqi Sun
- Laboratory of Transplant Immunology, Xuzhou Medical College, Xuzhou, China
| | - Qingyun Wu
- Laboratory of Transplant Immunology, Xuzhou Medical College, Xuzhou, China
| | - Kai Zhao
- Laboratory of Transplant Immunology, Xuzhou Medical College, Xuzhou, China
| | - Lingyu Zeng
- Laboratory of Transplant Immunology, Xuzhou Medical College, Xuzhou, China
| | - Kailin Xu
- Department of Hematology, The Affiliated Hospital of Xuzhou Medical College, Xuzhou, China; Laboratory of Transplant Immunology, Xuzhou Medical College, Xuzhou, China.
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12
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Garfin PM, Min D, Bryson JL, Serwold T, Edris B, Blackburn CC, Richie ER, Weinberg KI, Manley NR, Sage J, Viatour P. Inactivation of the RB family prevents thymus involution and promotes thymic function by direct control of Foxn1 expression. ACTA ACUST UNITED AC 2013; 210:1087-97. [PMID: 23669396 PMCID: PMC3674705 DOI: 10.1084/jem.20121716] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
RB family genes control T cell production and promote thymic involution through reducing Foxn1 expression in thymic epithelial cells. Thymic involution during aging is a major cause of decreased production of T cells and reduced immunity. Here we show that inactivation of Rb family genes in young mice prevents thymic involution and results in an enlarged thymus competent for increased production of naive T cells. This phenotype originates from the expansion of functional thymic epithelial cells (TECs). In RB family mutant TECs, increased activity of E2F transcription factors drives increased expression of Foxn1, a central regulator of the thymic epithelium. Increased Foxn1 expression is required for the thymic expansion observed in Rb family mutant mice. Thus, the RB family promotes thymic involution and controls T cell production via a bone marrow–independent mechanism, identifying a novel pathway to target to increase thymic function in patients.
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Affiliation(s)
- Phillip M Garfin
- Department of Pediatrics, Stanford University, Stanford, CA 94305, USA
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13
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Saadoun S, Waters P, Macdonald C, Bridges LR, Bell BA, Vincent A, Verkman AS, Papadopoulos MC. T cell deficiency does not reduce lesions in mice produced by intracerebral injection of NMO-IgG and complement. J Neuroimmunol 2011; 235:27-32. [PMID: 21492943 DOI: 10.1016/j.jneuroim.2011.03.007] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2011] [Accepted: 03/17/2011] [Indexed: 10/18/2022]
Abstract
We reported recently that intracerebral administration of NMO-IgG with human complement produces neuromyelitis optica (NMO) lesions in mice. We examined the role of T cells in the formation of NMO lesions by comparing brain histopathology in wildtype and nude mice. Brains were co-injected with IgG from NMO patients and human complement. At 24h and 5days, wildtype vs. nude mouse brains had comparable inflammation (CD45 immunoreactivity), loss of myelin (Luxol Fast Blue staining) and loss of AQP4 immunoreactivity. We conclude that T cells are not required for the formation of NMO lesions in this mouse model.
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Affiliation(s)
- Samira Saadoun
- Academic Neurosurgery Unit, St. George's, University of London, London SW170RE, UK
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14
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Abstract
The autoimmune regulator (AIRE) gene encodes a transcription factor involved in the presentation of tissue-restricted antigens during T-cell development in the thymus. Mutations of this gene lead to type 1 autoimmune polyglandular syndrome (APS-1), also termed autoimmune polyendocrinopathy-candidiasis-ectodermal dystrophy (APECED) syndrome, which is characterized by the clinical presentation of at least two of a triad of underlying disorders: Addison disease, hypoparathyroidism and chronic mucocutaneous candidiasis. This Review describes the process of positive and negative selection of developing T cells in the thymus and the role of AIRE as a regulator of peripheral antigen presentation. Furthermore, it addresses how mutations of this gene lead to the failure to eliminate autoreactive T cells, which can lead to clinical autoimmune syndromes.
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Affiliation(s)
- Eitan M Akirav
- Department of Immunobiology and the School of Public Health, Yale University School of Medicine, 10 Amistad Street, New Haven, CT 06520, USA
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15
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Schaffer BS, Grayson MH, Wortham JM, Kubicek CB, McCleish AT, Prajapati SI, Nelon LD, Brady MM, Jung I, Hosoyama T, Sarro LM, Hanes MA, Rubin BP, Michalek JE, Clifford CB, Infante AJ, Keller C. Immune competency of a hairless mouse strain for improved preclinical studies in genetically engineered mice. Mol Cancer Ther 2010; 9:2354-64. [PMID: 20663932 DOI: 10.1158/1535-7163.mct-10-0207] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Genetically engineered mouse models (GEMM) of cancer are of increasing value to preclinical therapeutics. Optical imaging is a cost-effective method of assessing deep-seated tumor growth in GEMMs whose tumors can be encoded to express luminescent or fluorescent reporters, although reporter signal attenuation would be improved if animals were fur-free. In this study, we sought to determine whether hereditable furlessness resulting from a hypomorphic mutation in the Hairless gene would or would not also affect immune competence. By assessing humoral and cellular immunity of the SKH1 mouse line bearing the hypomorphic Hairless mutation, we determined that blood counts, immunoglobulin levels, and CD4+ and CD8+ T cells were comparable between SKH1 and the C57Bl/6 strain. On examination of T-cell subsets, statistically significant differences in naïve T cells (1.7 versus 3.4 x 10(5) cells/spleen in SKH1 versus C57Bl/6, P = 0.008) and memory T cells (1.4 versus 0.13 x 10(6) cells/spleen in SKH1 versus C57Bl/6, P = 0.008) were detected. However, the numerical differences did not result in altered T-cell functional response to antigen rechallenge (keyhole limpet hemocyanin) in a lymph node cell in vitro proliferative assay. Furthermore, interbreeding the SKH1 mouse line to a rhabdomyosarcoma GEMM showed preserved antitumor responses of CD56+ natural killer cells and CD163+ macrophages, without any differences in tumor pathology. The fur-free GEMM was also especially amenable to multiplex optical imaging. Thus, SKH1 represents an immune competent, fur-free mouse strain that may be of use for interbreeding to other genetically engineered mouse models of cancer for improved preclinical studies.
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Affiliation(s)
- Beverly S Schaffer
- Greehey Children's Cancer Research Institute, University of Texas Health Science Center, San Antonio, Texas, USA
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16
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Transcriptional regulation of thymus organogenesis and thymic epithelial cell differentiation. PROGRESS IN MOLECULAR BIOLOGY AND TRANSLATIONAL SCIENCE 2010; 92:103-20. [PMID: 20800818 DOI: 10.1016/s1877-1173(10)92005-x] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Transcriptional regulatory networks are the central regulatory mechanisms that control organ identity, patterning, and differentiation. In the case of the thymus, several key transcription factors have been identified that are critical for various aspects of thymus organogenesis and thymic epithelial cell (TEC) differentiation. The thymus forms from the third pharyngeal pouch endoderm during embryogenesis. Organ development progresses from initial thymus cell fate specification, through multiple stages of TEC differentiation and cortical (cTEC) and medullary (mTEC) formation. Transcription factors have been identified for each of these stages: a Hoxa3-dependent cascade at initial fate specification, Foxn1 for early (and later) TEC differentiation, and NF-kappaB for mTEC differentiation. As important as these factors are, their interrelationships are not understood, and many more transcription factors are likely required for complete thymus organogenesis to occur. In this chapter, we review the literature on these known genes, as well as identify gaps in our knowledge for future studies.
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17
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Zuklys S, Gill J, Keller MP, Hauri-Hohl M, Zhanybekova S, Balciunaite G, Na KJ, Jeker LT, Hafen K, Tsukamoto N, Amagai T, Taketo MM, Krenger W, Holländer GA. Stabilized beta-catenin in thymic epithelial cells blocks thymus development and function. THE JOURNAL OF IMMUNOLOGY 2009; 182:2997-3007. [PMID: 19234195 DOI: 10.4049/jimmunol.0713723] [Citation(s) in RCA: 66] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Thymic T cell development is dependent on a specialized epithelial microenvironment mainly composed of cortical and medullary thymic epithelial cells (TECs). The molecular programs governing the differentiation and maintenance of TECs remain largely unknown. Wnt signaling is central to the development and maintenance of several organ systems but a specific role of this pathway for thymus organogenesis has not yet been ascertained. In this report, we demonstrate that activation of the canonical Wnt signaling pathway by a stabilizing mutation of beta-catenin targeted exclusively to TECs changes the initial commitment of endodermal epithelia to a thymic cell fate. Consequently, the formation of a correctly composed and organized thymic microenvironment is prevented, thymic immigration of hematopoietic precursors is restricted, and intrathymic T cell differentiation is arrested at a very early developmental stage causing severe immunodeficiency. These results suggest that a precise regulation of canonical Wnt signaling in thymic epithelia is essential for normal thymus development and function.
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Affiliation(s)
- Saulius Zuklys
- Department of Clinical-Biological Sciences, Laboratory of Pediatric Immunology, University of Basel, and Basel University Children's Hospital, Basel, Switzerland
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18
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Abstract
The epithelial architecture of the thymus fosters growth, differentiation, and T cell receptor repertoire selection of large numbers of immature T cells that continuously feed the mature peripheral T cell pool. Failure to build or to maintain a proper thymus structure can lead to defects ranging from immunodeficiency to autoimmunity. There has been long-standing interest in unraveling the cellular and molecular basis of thymus organogenesis. Earlier studies gave important morphological clues on thymus development. More recent cell biological and genetic approaches yielded new and conclusive insights regarding the germ layer origin of the epithelium and the composition of the medulla as a mosaic of clonally derived islets. The existence of epithelial progenitors common for cortex and medulla with the capacity for forming functional thymus after birth has been uncovered. In addition to the thymus in the chest, mice can have a cervical thymus that is small, but functional, and produces T cells only after birth. It will be important to elucidate the pathways from putative thymus stem cells to mature thymus epithelial cells, and the properties and regulation of these pathways from ontogeny to thymus involution.
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19
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Weiner L, Han R, Scicchitano BM, Li J, Hasegawa K, Grossi M, Lee D, Brissette JL. Dedicated epithelial recipient cells determine pigmentation patterns. Cell 2007; 130:932-42. [PMID: 17803914 DOI: 10.1016/j.cell.2007.07.024] [Citation(s) in RCA: 88] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2007] [Revised: 05/28/2007] [Accepted: 07/13/2007] [Indexed: 11/26/2022]
Abstract
Mammals generate external coloration via dedicated pigment-producing cells but arrange pigment into patterns through mechanisms largely unknown. Here, using mice as models, we show that patterns ultimately emanate from dedicated pigment-receiving cells. These pigment recipients are epithelial cells that recruit melanocytes to their position in the skin and induce the transfer of melanin. We identify Foxn1 (a transcription factor) as an activator of this "pigment recipient phenotype" and Fgf2 (a growth factor and Foxn1 target) as a signal released by recipients. When Foxn1 - and thus dedicated recipients - are redistributed in the skin, new patterns of pigmentation develop, suggesting a mechanism for the evolution of coloration. We conclude that recipients provide a cutaneous template or blueprint that instructs melanocytes where to place pigment. As Foxn1 and Fgf2 also modulate epithelial growth and differentiation, the Foxn1 pathway should serve as a nexus coordinating cell division, differentiation, and pigmentation.
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MESH Headings
- Animals
- Antibodies
- Cell Differentiation
- Cell Movement
- Cell Proliferation
- Cells, Cultured
- Fibroblast Growth Factor 2/genetics
- Fibroblast Growth Factor 2/immunology
- Fibroblast Growth Factor 2/metabolism
- Forkhead Transcription Factors/deficiency
- Forkhead Transcription Factors/genetics
- Forkhead Transcription Factors/metabolism
- Hair Color/physiology
- Hair Follicle/metabolism
- Humans
- Keratin-15
- Keratin-5/genetics
- Keratinocytes/metabolism
- Melanins/metabolism
- Melanocytes/metabolism
- Mice
- Mice, Inbred C57BL
- Mice, Inbred DBA
- Mice, Knockout
- Mice, Nude
- Mice, Transgenic
- Phenotype
- Promoter Regions, Genetic
- RNA, Messenger/metabolism
- Signal Transduction
- Skin/cytology
- Skin/growth & development
- Skin/metabolism
- Skin Pigmentation/physiology
- Time Factors
- Transcription, Genetic
- Transduction, Genetic
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Affiliation(s)
- Lorin Weiner
- Cutaneous Biology Research Center, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA 02129, USA
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20
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Abstract
The thymus provides the essential microenvironment for T-cell development and maturation. Thymic epithelial cells (TECs), which are composed of thymic cortical epithelial cells (cTECs) and thymic medullary epithelial cells (mTECs), have been well documented to be critical for these tightly regulated processes. It has long been controversial whether the common progenitor cells of TECs could give rise to both cTECs and mTECs. Great progress has been made to characterize the common TEC progenitor cells in recent years. We herein discuss the sole origin paradigm with regard to TEC differentiation as well as these progenitor cells in thymus regeneration.
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Affiliation(s)
- Lianjun Zhang
- Transplantation Biology Research Division, State Key Laboratory of Biomembrane and Membrane Biotechnology, Institute of Zoology, Chinese Academy of Sciences, Beijing 100080, China
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21
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Holländer G, Gill J, Zuklys S, Iwanami N, Liu C, Takahama Y. Cellular and molecular events during early thymus development. Immunol Rev 2006; 209:28-46. [PMID: 16448532 DOI: 10.1111/j.0105-2896.2006.00357.x] [Citation(s) in RCA: 85] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
The thymic stromal compartment consists of several cell types that collectively enable the attraction, survival, expansion, migration, and differentiation of T-cell precursors. The thymic epithelial cells constitute the most abundant cell type of the thymic microenvironment and can be differentiated into morphologically, phenotypically, and functionally separate subpopulations of the postnatal thymus. All thymic epithelial cells are derived from the endodermal lining of the third pharyngeal pouch. Very soon after the formation of a thymus primordium and prior to its vascularization, thymic epithelial cells orchestrate the first steps of intrathymic T-cell development, including the attraction of lymphoid precursor cells to the thymic microenvironment. The correct segmentation of pharyngeal epithelial cells and their subsequent crosstalk with cells in the pharyngeal arches are critical prerequisites for the formation of a thymus anlage. Mutations in several transcription factors and their target genes have been informative to detail some of the complex mechanisms that control the development of the thymus anlage. This review highlights recent findings related to the genetic control of early thymus organogenesis and provides insight into the molecular basis by which lymphocyte precursors are attracted to the thymus.
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Affiliation(s)
- Georg Holländer
- Pediatric Immunology, The Center for Biomedicine, Department of Clinical-Biological Sciences, University of Basel, and The University Children's Hospital of Basel, Basel, Switzerland.
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22
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Abstract
In mice, rats, and humans, loss of function of Foxn1, a member of the winged helix/forkhead family of transcription factors, leads to macroscopic nudity and an inborn dysgenesis of the thymus. Nude (Foxn1(nu)/Foxn1(nu)) mice develop largely normal hair follicles and produce hair shafts. However, presumably because of a lack of certain hair keratins, the hair shafts that are generated twist and coil in the hair follicle infundibulum, which becomes dilated. Since hair shafts fail to penetrate the epidermis, macroscopic nudity results and generates the - grossly misleading - impression that nude mice are hairless. Here, we provide an overview of what is known on the role of Foxn1 in mammalian skin biology, its expression patterns in the hair follicle, its influence on hair follicle function, and onychocyte differentiation. We focus on the mechanisms and signaling pathways by which Foxn1 modulates keratinocyte differentiation in the hair follicle and nail apparatus and summarize the current knowledge on the molecular and functional consequences of a loss of function of the Foxn1 protein in skin. Foxn1 target genes, gene regulation of Foxn, and pharmacological manipulation of the nude phenotype (e.g. by cyclosporine A, KGF, and vitamin D3) are discussed, and important open questions as well as promising research strategies in Foxn1 biology are defined. Taken together, this review aims at delineating why enhanced research efforts in this comparatively neglected field of investigative dermatology promise important new insights into the controls of epithelial differentiation in mammalian skin.
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Affiliation(s)
- Lars Mecklenburg
- Department of Pathobiology, College of Veterinary Medicine, Texas A&M University, College Station, USA
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23
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Johns SA, Soullier S, Rashbass P, Cunliffe VT. Foxn1 is required for tissue assembly and desmosomal cadherin expression in the hair shaft. Dev Dyn 2005; 232:1062-8. [PMID: 15739220 DOI: 10.1002/dvdy.20278] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
The mouse nude mutation inactivates the gene encoding the Foxn1 transcription factor, causing defective hair morphogenesis. Here, we show for the first time that Foxn1 is required for proper assembly of the hair medulla, and we identify Foxn1-regulated genes by transcript profiling. One such gene encodes the desmosomal cadherin, Dsc2. Significantly, Foxn1-dependent Dsc2 expression is restricted to the hair medulla, and within these cells, Dsc2 protein is predominantly localized to specialized adhesion junctions between the cortex and the medulla. Our results reveal Foxn1 as an essential regulator of tissue assembly in the growing hair shaft and implicate Dsc2 as a downstream effector of this activity.
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Affiliation(s)
- Sarah A Johns
- Centre for Developmental Genetics, School of Medicine and Biomedical Science, University of Sheffield, Firth Court, Western Bank, Sheffield, S10 2TN, United Kingdom
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24
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Mecklenburg L, Paus R, Halata Z, Bechtold LS, Fleckman P, Sundberg JP. FOXN1 is critical for onycholemmal terminal differentiation in nude (Foxn1) mice. J Invest Dermatol 2005; 123:1001-11. [PMID: 15610506 DOI: 10.1111/j.0022-202x.2004.23442.x] [Citation(s) in RCA: 54] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Nude mice have a mutation in the transcription factor Foxn1(nu), resulting in downregulation of hair keratins. Although hair follicles develop normally, the hair fibers become structurally weak, curl, and break off at the surface. Nails in nude mice are deformed, based on alterations of the onychocyte differentiation process. Elemental microanalysis of the nail plate reveals marked decreases in sulfur concentrations in the nude mouse nail plates. Immunohistochemistry shows a lack of keratin 1 expression in terminally differentiating keratinocytes of the nail matrix. Instead, the typical differentiation process of the matrix is altered toward an epidermis-like differentiation pattern, comprising the production of filaggrin-containing keratohyalin granules in cells resembling those of the stratum granulosum, which are never observed in normally haired mice. The nail plate has diffuse basophilic stippling. It is thinner than normal, weak, and in most Foxn1(nu)/Foxn1(nu) mice breaks where it separates from the hyponychium. These studies indicate that the Foxn1(nu) mutated gene has effects beyond downregulating keratin expression, including changes in filaggrin expression, and is critical for normal onycholemmal differentiation. The nails of nude mice provide new insights into the molecular controls of onychocyte differentiation, and they offer a useful model to investigate the pathogenesis of nail hypergranulosis, a common feature in human nail diseases.
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Affiliation(s)
- Lars Mecklenburg
- Department of Dermatology, University Hospital Hamburg-Eppendorf, University of Hamburg, Hamburg, Germany
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25
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Abstract
Substantial progress has been made regarding the elucidation of differentiation processes of the human hair follicle. This review first describes the genomic organization of the human hair keratin gene family and the complex expression characteristics of hair keratins in the hair-forming compartment. Sections describe the role and fate of hair keratins in the diseased hair follicle, particularly hereditary disorders and hair follicle-derived tumors. Also included is a report on the actual state of knowledge concerning the regulation of hair keratin expression. In the second part of this review, essentially the same principles are applied to outline more recent and, thus, occasionally fewer data on specialized epithelial keratins expressed in various tissue constituents of the external sheaths and the companion layer of the follicle. A closing outlook highlights issues that need to be explored further to deepen our insight into the biology and genetics of the hair follicle.
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Affiliation(s)
- Lutz Langbein
- Division of Cell Biology, German Cancer Research Center, Heidelberg, Germany
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26
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Balciunaite G, Keller MP, Balciunaite E, Piali L, Zuklys S, Mathieu YD, Gill J, Boyd R, Sussman DJ, Holländer GA. Wnt glycoproteins regulate the expression of FoxN1, the gene defective in nude mice. Nat Immunol 2002; 3:1102-8. [PMID: 12379851 DOI: 10.1038/ni850] [Citation(s) in RCA: 206] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2002] [Accepted: 09/09/2002] [Indexed: 11/09/2022]
Abstract
T cell development and selection require the fully mature and diverse epithelial microenvironment of the thymus. Acquisition of these characteristics is dependent on expression of the forkhead (also known as winged-helix) transcription factor FoxN1, as a lack of functional FoxN1 results in aberrant epithelial morphogenesis and an inability to attract lymphoid precursors to the thymus primordium. However, the transcriptional control of Foxn1 expression has not been elucidated. Here we report that secreted Wnt glycoproteins, expressed by thymic epithelial cells and thymocytes, regulate epithelial Foxn1 expression in both autocrine and paracrine fashions. Wnt molecules therefore provide regulatory signals critical for thymic function.
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Affiliation(s)
- Gina Balciunaite
- Pediatric Immunology, Department of Research and Clinical-biological Sciences, and the Children's Hospital, University of Basel, Basel, Switzerland
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