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Cuevas-Diaz Duran R, Martinez-Ledesma E, Garcia-Garcia M, Bajo Gauzin D, Sarro-Ramírez A, Gonzalez-Carrillo C, Rodríguez-Sardin D, Fuentes A, Cardenas-Lopez A. The Biology and Genomics of Human Hair Follicles: A Focus on Androgenetic Alopecia. Int J Mol Sci 2024; 25:2542. [PMID: 38473791 DOI: 10.3390/ijms25052542] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2024] [Revised: 02/16/2024] [Accepted: 02/18/2024] [Indexed: 03/14/2024] Open
Abstract
Androgenetic alopecia is a highly prevalent condition mainly affecting men. This complex trait is related to aging and genetics; however, multiple other factors, for example, lifestyle, are also involved. Despite its prevalence, the underlying biology of androgenetic alopecia remains elusive, and thus advances in its treatment have been hindered. Herein, we review the functional anatomy of hair follicles and the cell signaling events that play a role in follicle cycling. We also discuss the pathology of androgenetic alopecia and the known molecular mechanisms underlying this condition. Additionally, we describe studies comparing the transcriptional differences in hair follicles between balding and non-balding scalp regions. Given the genetic contribution, we also discuss the most significant risk variants found to be associated with androgenetic alopecia. A more comprehensive understanding of this pathology may be generated through using multi-omics approaches.
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Affiliation(s)
- Raquel Cuevas-Diaz Duran
- Tecnologico de Monterrey, Escuela de Medicina y Ciencias de la Salud, Monterrey 64710, NL, Mexico
- CapilarFix®, Monterrey 66220, NL, Mexico
| | - Emmanuel Martinez-Ledesma
- Tecnologico de Monterrey, Escuela de Medicina y Ciencias de la Salud, Monterrey 64710, NL, Mexico
- Tecnologico de Monterrey, Institute for Obesity Research, Monterrey 64849, NL, Mexico
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Trager MH, Sah B, Chen Z, Liu L. Control of Breast Cancer Pathogenesis by Histone Methylation and the Hairless Histone Demethylase. Endocrinology 2021; 162:6259332. [PMID: 33928351 PMCID: PMC8237996 DOI: 10.1210/endocr/bqab088] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/31/2021] [Indexed: 12/19/2022]
Abstract
Breast cancer is a highly heterogeneous disease, encompassing many subtypes that have distinct origins, behaviors, and prognoses. Although traditionally seen as a genetic disease, breast cancer is now also known to involve epigenetic abnormalities. Epigenetic regulators, such as DNA methyltransferases and histone-modifying enzymes, play essential roles in gene regulation and cancer development. Dysregulation of epigenetic regulator activity has been causally linked with breast cancer pathogenesis. Hairless (HR) encodes a 130-kDa transcription factor that is essential for development and tissue homeostasis. Its role in transcription regulation is partly mediated by its interaction with multiple nuclear receptors, including thyroid hormone receptor, retinoic acid receptor-related orphan receptors, and vitamin D receptor. HR has been studied primarily in epidermal development and homeostasis. Hr-mutant mice are highly susceptible to ultraviolet- or carcinogen-induced skin tumors. Besides its putative tumor suppressor function in skin, loss of HR function has also been implicated in increased leukemia susceptibility and promotes the growth of melanoma and brain cancer cells. HR has also been demonstrated to function as a histone H3 lysine 9 demethylase. Recent genomics studies have identified HR mutations in a variety of human cancers, including breast cancer. The anticancer function and mechanism of action by HR in mammary tissue remains to be investigated. Here, we review the emerging role of HR, its histone demethylase activity and histone methylation in breast cancer development, and potential for epigenetic therapy.
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Affiliation(s)
- Megan H Trager
- Columbia University Vagelos College of Physicians and Surgeons, New York, New York 10032, USA
| | - Bindeshwar Sah
- The Hormel Institute, University of Minnesota, Austin, Minnesota 55912, USA
| | - Zhongming Chen
- The Hormel Institute, University of Minnesota, Austin, Minnesota 55912, USA
- Masonic Cancer Center, University of Minnesota, Minneapolis, Minnesota 55912, USA
| | - Liang Liu
- The Hormel Institute, University of Minnesota, Austin, Minnesota 55912, USA
- Masonic Cancer Center, University of Minnesota, Minneapolis, Minnesota 55912, USA
- Correspondence: Liang Liu, PhD, The Hormel Institute, University of Minnesota, Austin, MN, 55912, USA.
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Bi-allelic Mutations in LSS, Encoding Lanosterol Synthase, Cause Autosomal-Recessive Hypotrichosis Simplex. Am J Hum Genet 2018; 103:777-785. [PMID: 30401459 DOI: 10.1016/j.ajhg.2018.09.011] [Citation(s) in RCA: 39] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2018] [Accepted: 09/22/2018] [Indexed: 12/25/2022] Open
Abstract
Hypotrichosis simplex (HS) is a rare form of hereditary alopecia characterized by childhood onset of diffuse and progressive scalp and body hair loss. Although research has identified a number of causal genes, genetic etiology in about 50% of HS cases remains unknown. The present report describes the identification via whole-exome sequencing of five different mutations in the gene LSS in three unrelated families with unexplained, potentially autosomal-recessive HS. Affected individuals showed sparse to absent lanugo-like scalp hair, sparse and brittle eyebrows, and sparse eyelashes and body hair. LSS encodes lanosterol synthase (LSS), which is a key enzyme in the cholesterol biosynthetic pathway. This pathway plays an important role in hair follicle biology. After localizing LSS protein expression in the hair shaft and bulb of the hair follicle, the impact of the mutations on keratinocytes was analyzed using immunoblotting and immunofluorescence. Interestingly, wild-type LSS was localized in the endoplasmic reticulum (ER), whereas mutant LSS proteins were localized in part outside of the ER. A plausible hypothesis is that this mislocalization has potential deleterious implications for hair follicle cells. Immunoblotting revealed no differences in the overall level of wild-type and mutant protein. Analyses of blood cholesterol levels revealed no decrease in cholesterol or cholesterol intermediates, thus supporting the previously proposed hypothesis of an alternative cholesterol pathway. The identification of LSS as causal gene for autosomal-recessive HS highlights the importance of the cholesterol pathway in hair follicle biology and may facilitate novel therapeutic approaches for hair loss disorders in general.
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Ogawa Y, Kawamura T, Shimada S. Zinc and skin biology. Arch Biochem Biophys 2016; 611:113-119. [PMID: 27288087 DOI: 10.1016/j.abb.2016.06.003] [Citation(s) in RCA: 72] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2016] [Revised: 06/01/2016] [Accepted: 06/03/2016] [Indexed: 01/08/2023]
Abstract
Of all tissues, the skin has the third highest abundance of zinc in the body. In the skin, the zinc concentration is higher in the epidermis than in the dermis, owing to a zinc requirement for the active proliferation and differentiation of epidermal keratinocytes. Here we review the dynamics and functions of zinc in the skin as well as skin disorders associated with zinc deficiency, zinc finger domain-containing proteins, and zinc transporters. Among skin disorders associated with zinc deficiency, acrodermatitis enteropathica is a disorder caused by mutations in the ZIP4 transporter and subsequent zinc deficiency. The triad acrodermatitis enteropathica is characterized by alopecia, diarrhea, and skin lesions in acral, periorificial, and anogenital areas. We highlight the underlying mechanism of the development of acrodermatitis because of zinc deficiency by describing our new findings. We also discuss the accumulating evidence on zinc deficiency in alopecia and necrolytic migratory erythema, which is typically associated with glucagonomas.
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Affiliation(s)
- Youichi Ogawa
- Department of Dermatology, Faculty of Medicine, University of Yamanashi, Yamanashi, 409-3898, Japan.
| | - Tatsuyoshi Kawamura
- Department of Dermatology, Faculty of Medicine, University of Yamanashi, Yamanashi, 409-3898, Japan
| | - Shinji Shimada
- Department of Dermatology, Faculty of Medicine, University of Yamanashi, Yamanashi, 409-3898, Japan
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Mehmood S, Jan A, Raza SI, Ahmad F, Younus M, Irfanullah, Shahi S, Ayub M, Khan S, Ahmad W. Disease causing homozygous variants in the human hairless gene. Int J Dermatol 2015; 55:977-81. [DOI: 10.1111/ijd.13109] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/05/2015] [Revised: 04/25/2015] [Accepted: 05/07/2015] [Indexed: 11/30/2022]
Affiliation(s)
- Sabba Mehmood
- Department of Biochemistry; Faculty of Biological Sciences; Quaid-i-Azam University; Islamabad Pakistan
| | - Abid Jan
- Department of Biochemistry; Faculty of Biological Sciences; Quaid-i-Azam University; Islamabad Pakistan
- Department of Biotechnology & Genetic Engineering; Kohat University of Science & Technology (KUST); Kohat Pakistan
| | - Syed Irfan Raza
- Department of Biochemistry; Faculty of Biological Sciences; Quaid-i-Azam University; Islamabad Pakistan
- Army Medical College; National University of Science & Technology (NUST); Islamabad Pakistan
| | - Farooq Ahmad
- Department of Biochemistry; Faculty of Biological Sciences; Quaid-i-Azam University; Islamabad Pakistan
| | - Muhammad Younus
- Department of Biochemistry; Faculty of Biological Sciences; Quaid-i-Azam University; Islamabad Pakistan
| | - Irfanullah
- Department of Biochemistry; Faculty of Biological Sciences; Quaid-i-Azam University; Islamabad Pakistan
| | - Shamim Shahi
- Department of Biochemistry; Faculty of Biological Sciences; Quaid-i-Azam University; Islamabad Pakistan
| | - Muhammad Ayub
- Institute of Biochemistry; University of Baluchistan; Quetta Pakistan
| | - Saadullah Khan
- Department of Biotechnology & Genetic Engineering; Kohat University of Science & Technology (KUST); Kohat Pakistan
| | - Wasim Ahmad
- Department of Biochemistry; Faculty of Biological Sciences; Quaid-i-Azam University; Islamabad Pakistan
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Jan A, Basit S, Wakil SM, Ramzan K, Ahmad W. A novel homozygous variant in the dsp gene underlies the first case of non-syndromic form of alopecia. Arch Dermatol Res 2015; 307:793-801. [DOI: 10.1007/s00403-015-1590-y] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2015] [Revised: 05/31/2015] [Accepted: 06/29/2015] [Indexed: 02/04/2023]
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Kember RL, Georgi B, Bailey-Wilson JE, Stambolian D, Paul SM, Bućan M. Copy number variants encompassing Mendelian disease genes in a large multigenerational family segregating bipolar disorder. BMC Genet 2015; 16:27. [PMID: 25887117 PMCID: PMC4382929 DOI: 10.1186/s12863-015-0184-1] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2014] [Accepted: 02/19/2015] [Indexed: 12/20/2022] Open
Abstract
BACKGROUND Bipolar affective disorder (BP) is a common, highly heritable psychiatric disorder characterized by periods of depression and mania. Using dense SNP genotype data, we characterized CNVs in 388 members of an Old Order Amish Pedigree with bipolar disorder. We identified CNV regions arising from common ancestral mutations by utilizing the pedigree information. By combining this analysis with whole genome sequence data in the same individuals, we also explored the role of compound heterozygosity. RESULTS Here we describe 541 inherited CNV regions, of which 268 are rare in a control population of European origin but present in a large number of Amish individuals. In addition, we highlight a set of CNVs found at higher frequencies in BP individuals, and within genes known to play a role in human development and disease. As in prior reports, we find no evidence for an increased burden of CNVs in BP individuals, but we report a trend towards a higher burden of CNVs in known Mendelian disease loci in bipolar individuals (BPI and BPII, p = 0.06). CONCLUSIONS We conclude that CNVs may be contributing factors in the phenotypic presentation of mood disorders and co-morbid medical conditions in this family. These results reinforce the hypothesis of a complex genetic architecture underlying BP disorder, and suggest that the role of CNVs should continue to be investigated in BP data sets.
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Affiliation(s)
- Rachel L Kember
- Department of Genetics, University of Pennsylvania, Philadelphia, PA, USA.
| | - Benjamin Georgi
- Department of Genetics, University of Pennsylvania, Philadelphia, PA, USA.
| | - Joan E Bailey-Wilson
- Computational and Statistical Genomics Branch, National Human Genome Research Institute, National Institutes of Health, Baltimore, MD, USA.
| | - Dwight Stambolian
- Department of Ophthalmology, University of Pennsylvania, Philadelphia, PA, USA.
| | - Steven M Paul
- Appel Alzheimer's Disease Research Institute, Mind and Brain Institute, Weill Cornell Medical College, New York, NY, USA.
| | - Maja Bućan
- Department of Genetics, University of Pennsylvania, Philadelphia, PA, USA. .,Department of Psychiatry, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA.
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Basit S, Khan S, Ahmad W. Genetics of human isolated hereditary hair loss disorders. Clin Genet 2014; 88:203-12. [DOI: 10.1111/cge.12531] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2014] [Revised: 09/22/2014] [Accepted: 10/23/2014] [Indexed: 12/25/2022]
Affiliation(s)
- S. Basit
- Center for Genetics and Inherited Diseases; Taibah University; Almadinah Almunawwarah Saudi Arabia
| | - S. Khan
- Department of Biotechnology and Genetic Engineering; Kohat University of Science and Technology; Khyber Pakhtunkhwa Pakistan
| | - W. Ahmad
- Department of Biochemistry, Faculty of Biological Sciences; Quaid-i-Azam University; Islamabad Pakistan
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Devos M, De Groote P, Gilbert B, Bruggeman I, Leurs K, Lippens S, Vandenabeele P, Declercq W. Caspase-14 overexpression in hairless mice is not involved in utricle formation. Exp Dermatol 2013; 22:484-6. [DOI: 10.1111/exd.12165] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/03/2013] [Indexed: 01/12/2023]
Affiliation(s)
- Michael Devos
- Molecular Signaling and Cell Death Unit; Department for Molecular Biomedical Research; VIB; Ghent Belgium
- Department of Biomedical Molecular Biology; Ghent University; Ghent Belgium
| | - Philippe De Groote
- Molecular Signaling and Cell Death Unit; Department for Molecular Biomedical Research; VIB; Ghent Belgium
- Department of Biomedical Molecular Biology; Ghent University; Ghent Belgium
| | - Barbara Gilbert
- Molecular Signaling and Cell Death Unit; Department for Molecular Biomedical Research; VIB; Ghent Belgium
- Department of Biomedical Molecular Biology; Ghent University; Ghent Belgium
| | - Inge Bruggeman
- Molecular Signaling and Cell Death Unit; Department for Molecular Biomedical Research; VIB; Ghent Belgium
- Department of Biomedical Molecular Biology; Ghent University; Ghent Belgium
| | - Kirsten Leurs
- Molecular Signaling and Cell Death Unit; Department for Molecular Biomedical Research; VIB; Ghent Belgium
- Department of Biomedical Molecular Biology; Ghent University; Ghent Belgium
| | - Saskia Lippens
- Molecular Signaling and Cell Death Unit; Department for Molecular Biomedical Research; VIB; Ghent Belgium
- Department of Biomedical Molecular Biology; Ghent University; Ghent Belgium
| | - Peter Vandenabeele
- Molecular Signaling and Cell Death Unit; Department for Molecular Biomedical Research; VIB; Ghent Belgium
- Department of Biomedical Molecular Biology; Ghent University; Ghent Belgium
| | - Wim Declercq
- Molecular Signaling and Cell Death Unit; Department for Molecular Biomedical Research; VIB; Ghent Belgium
- Department of Biomedical Molecular Biology; Ghent University; Ghent Belgium
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Chen Z, Wang Z, Xu S, Zhou K, Yang G. Characterization of hairless (Hr) and FGF5 genes provides insights into the molecular basis of hair loss in cetaceans. BMC Evol Biol 2013; 13:34. [PMID: 23394579 PMCID: PMC3608953 DOI: 10.1186/1471-2148-13-34] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2012] [Accepted: 01/30/2013] [Indexed: 11/29/2022] Open
Abstract
Background Hair is one of the main distinguishing characteristics of mammals and it has many important biological functions. Cetaceans originated from terrestrial mammals and they have evolved a series of adaptations to aquatic environments, which are of evolutionary significance. However, the molecular mechanisms underlying their aquatic adaptations have not been well explored. This study provided insights into the evolution of hair loss during the transition from land to water by investigating and comparing two essential regulators of hair follicle development and hair follicle cycling, i.e., the Hairless (Hr) and FGF5 genes, in representative cetaceans and their terrestrial relatives. Results The full open reading frame sequences of the Hr and FGF5 genes were characterized in seven cetaceans. The sequence characteristics and evolutionary analyses suggested the functional loss of the Hr gene in cetaceans, which supports the loss of hair during their full adaptation to aquatic habitats. By contrast, positive selection for the FGF5 gene was found in cetaceans where a series of positively selected amino acid residues were identified. Conclusions This is the first study to investigate the molecular basis of the hair loss in cetaceans. Our investigation of Hr and FGF5, two indispensable regulators of the hair cycle, provide some new insights into the molecular basis of hair loss in cetaceans. The results suggest that positive selection for the FGF5 gene might have promoted the termination of hair growth and early entry into the catagen stage of hair follicle cycling. Consequently, the hair follicle cycle was disrupted and the hair was lost completely due to the loss of the Hr gene function in cetaceans. This suggests that cetaceans have evolved an effective and complex mechanism for hair loss.
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Affiliation(s)
- Zhuo Chen
- Jiangsu Key Laboratory for Biodiversity and Biotechnology, College of Life Sciences, Nanjing Normal University, Nanjing 210023, China
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Wang S, Tu C, Feng Y, Wang X, Zhang D, Xiao S. Atrichia with Papular Lesions in a Chinese Family Caused by Novel Compound Heterozygous Mutations and Literature Review. Dermatology 2013; 226:68-74. [DOI: 10.1159/000346753] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2012] [Accepted: 12/24/2012] [Indexed: 11/19/2022] Open
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Unveiling the roots of monogenic genodermatoses: genotrichoses as a paradigm. J Invest Dermatol 2011; 132:906-14. [PMID: 22170492 DOI: 10.1038/jid.2011.408] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
The past two decades have seen significant and unprecedented progress in human genetics owing to the advent of novel molecular biological technologies and major developments in computational methods. Dermatology has benefited from and, in some cases, led these advances. In this article, we review major discoveries in the field of inherited hair diseases, which illustrate the changes that genodermatology has undergone in recent years from a mostly descriptive discipline through the elucidation of the molecular basis of numerous disorders, up to the first attempts at translating these new findings into novel preventive and therapeutic tools to the benefit of our patients.
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Malloy PJ, Feldman D. The role of vitamin D receptor mutations in the development of alopecia. Mol Cell Endocrinol 2011; 347:90-6. [PMID: 21693169 PMCID: PMC3196847 DOI: 10.1016/j.mce.2011.05.045] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/08/2011] [Revised: 05/27/2011] [Accepted: 05/28/2011] [Indexed: 12/22/2022]
Abstract
Hereditary Vitamin D Resistant Rickets (HVDRR) is a rare disease caused by mutations in the vitamin D receptor (VDR). The consequence of defective VDR is the inability to absorb calcium normally in the intestine. This leads to a constellation of metabolic abnormalities including hypocalcemia, secondary hyperparathyroidism and hypophosphatemia that cause the development of rickets at an early age in affected children. An interesting additional abnormality is the presence of alopecia in some children depending on the nature of the VDR mutation. The data indicate that VDR mutations that cause defects in DNA binding, RXR heterodimerization or absence of the VDR cause alopecia while mutations that alter VDR affinity for 1,25(OH)(2)D(3) or disrupt coactivator interactions do not cause alopecia. The cumulative findings indicate that hair follicle cycling is dependent on unliganded actions of the VDR. Further research is ongoing to elucidate the role of the VDR in hair growth and differentiation.
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Affiliation(s)
- Peter J Malloy
- Stanford University School of Medicine, Stanford, CA 94305-5103, USA
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Kim JK, Kim BK, Park JK, Choi JH, KimYoon SJ. The Hairless Gene: A Putative Navigator of Hair Follicle Development. Genomics Inform 2011. [DOI: 10.5808/gi.2011.9.3.93] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
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15
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Refke M, Pasternack SM, Fiebig B, Wenzel S, Ishorst N, Ludwig M, Nöthen MM, Seyger MM, Hamel BC, Betz RC. Functional analysis of splice site mutations in the human hairless (HR) gene using a minigene assay. Br J Dermatol 2011; 165:1127-32. [PMID: 21718278 DOI: 10.1111/j.1365-2133.2011.10495.x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
BACKGROUND Congenital atrichia is a rare autosomal recessive form of isolated alopecia which is caused by mutations in the human hairless (HR) gene. Patients are born with normal hair that is shed almost completely and irreversibly during the first weeks of life. OBJECTIVES To investigate the molecular genetic basis of congenital atrichia in two patients, and to analyse the functional consequences of one newly identified and all seven previously identified HR splice site mutations using a minigene assay. METHODS Molecular analysis of the HR gene was performed by direct DNA sequencing. To analyse the functional consequences of the splice site mutations, the respective sequences were cloned into a vector which allows directed splicing. After transfection of COS7 cells, isolation of RNA and cDNA synthesis, sequencing was performed to analyse the products. RESULTS Two novel mutations were identified: an insertion in exon 2 (c.485insT; p.C162LfsX17), and a splice site mutation (c.2847-1G>A). In vitro analysis revealed aberrant splicing for all eight of the investigated HR splice site mutations. Comparison with the results of two biocomputational programs (neural network splice server and CRYP-SKIP) and calculation of consensus values revealed that the predictions of these two programs were consistent in only five and two of the eight mutations, respectively. CONCLUSIONS This is the first report to analyse the consequences of HR splice site mutations using a cell-based in vitro assay. The results highlight the importance of performing splicing experiments to clarify the consequences of putative splice site mutations.
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Affiliation(s)
- M Refke
- Institute of Human Genetics, University of Bonn, Bonn, Germany
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Basit S, Wali A, Aziz A, Muhammad N, Jelani M, Ahmad W. Digenic inheritance of an autosomal recessive hypotrichosis in two consanguineous pedigrees. Clin Genet 2011; 79:273-81. [PMID: 20528890 DOI: 10.1111/j.1399-0004.2010.01455.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
Hypotrichosis is a human hereditary hair loss disorder in which affected individuals show sparse to complete absence of hair on scalp and/or on different body parts. To date, at least eight isolated autosomal recessive and dominant forms of hypotrichosis loci have been mapped on different human chromosomes, and the corresponding genes have been identified. Detailed clinical and molecular studies were undertaken of the hereditary hypotrichosis observed in the two consanguineous families (A and B) presented here. Human genome scan, using >500 highly polymorphic microsatellite markers, identified equal evidence of linkage of the hypotrichosis phenotype on chromosomes 12q21.2-q22 and 16q21-q23.1 in both the families. The novel hypotrichosis locus on chromosome 12q21.2-q22 spans 16.3 cM (17.62 Mb), flanked by markers D12S326 and D12S101. At this locus, maximum multipoint logarithm of the odds ratio (LOD) scores of 3.68 and 3.31 were obtained in families A and B, respectively. The second hypotrichosis locus on chromosome 16q21-q23.1, identified in the two families, spans 5.58 cM (8.28 Mb) and is flanked by markers D16S3031 and D16S512. Maximum multipoint LOD scores of 3.17 and 3.31 were obtained with markers mapped at this locus in families A and B, respectively. DNA sequence analysis of six candidate genes (PLEKHG7, SLC6A15, VEZT, DUSP6, KERA and KITLG), located in the linkage interval on chromosome 12q21.2-q22, failed to detect potential sequence variants in the affected individuals of the two families. However, DNA sequence analysis of CDH3 gene, located on chromosome 16q21-q23.1, detected a single base pair homozygous insertion (c.1024_1025insG and p.342insGfsX345) in exon 9 in family A and deletion of four base pair (c.1859_1862delCTCT and p.620delSfsX629) in exon 13 in family B. We described for the first time digenic inheritance of an autosomal recessive hypotrichosis phenotype in two unlinked loci on chromosomes 12q21.2-q22 and 16q21-q23.1 in two unrelated consanguineous Pakistani families.
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Affiliation(s)
- S Basit
- Department of Biochemistry, Faculty of Biological Sciences, Quaid-i-Azam University, Islamabad, Pakistan
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Mapping of a novel autosomal recessive hypotrichosis locus on chromosome 10q11.23–22.3. Hum Genet 2011; 127:395-401. [PMID: 20054564 DOI: 10.1007/s00439-009-0784-9] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2009] [Accepted: 12/28/2009] [Indexed: 12/15/2022]
Abstract
Autosomal recessive hypotrichosis is a rare form of human genetic disorder characterized by sparse to absent hair on scalp and rest of the body of affected individuals. Over the past few years at least five autosomal recessive forms of hypotrichosis loci have been mapped on different human chromosomes. In the present study, we report localization of another novel autosomal recessive hypotrichosis locus on human chromosome 10q11.23-22.3 in a four generation consanguineous Pakistani family. All the four patients in the family showed typical features of hereditary hypotrichosis including sparse hair on the scalp and rest of the body. Human genome scan using highly polymorphic microsatellite markers mapped the disease locus to a large region on chromosome 10. This novel locus maps to 29.81 cM (28.5 Mb) region, flanked by markers D10S538 and D10S2327 on chromosome 10q11.23-22.3. A maximum multipoint LOD score of 3.26 was obtained with several markers in this region. DNA sequence analysis of exons and splice-junction sites of four putative candidate genes (P4HA1, ZNF365, ZMYND17, MYST4), located in the linkage interval, were sequenced but were negative for functional sequence variants.
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Bennàssar A, Ferrando J, Grimalt R. Congenital atrichia and hypotrichosis. World J Pediatr 2011; 7:111-7. [PMID: 21574026 DOI: 10.1007/s12519-011-0262-z] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/24/2009] [Accepted: 09/27/2010] [Indexed: 11/26/2022]
Abstract
BACKGROUND Alopecia present from birth includes a broad differential diagnosis and often represents a diagnostic and therapeutic challenge for the involved physician. DATA SOURCES An initial correct diagnosis and classification is essential because structural hair defects may be the expression of a genetic disorder affecting hair growth, part of a congenital syndrome with accompanying hair malformations, or a marker for an underlying metabolic disorder and may impact the mental and physical development of a child. Pathological hair loss rarely occurs in the first year of life; however, it may be a leading symptom of many congenital diseases. RESULTS In recent years, the clinical and microscopic features of hereditary hair shaft disorders have been characterized and classified. Furthermore, significant progress has been made in our knowledge of genes that control the normal development and differentiation of hair follicles, and thus the research is to define and classify the hair disorders within a genetic basis. CONCLUSIONS In this article we discuss several types of genotrichosis and provide a practical classification based on their clinical features.
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Affiliation(s)
- Antoni Bennàssar
- Department of Dermatology, Hospital Clínic, University of Barcelona, Barcelona, Spain
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Lee D, Kim SH, Chun JS, Joo MH, Kim JY, Hwang SW, Kang HJ, Park SW, Sung HS. Detection of a novel missense mutations in atrichia with papular lesions. Ann Dermatol 2011; 23:132-7. [PMID: 21747609 PMCID: PMC3130853 DOI: 10.5021/ad.2011.23.2.132] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2010] [Accepted: 10/03/2010] [Indexed: 11/08/2022] Open
Abstract
BACKGROUND Atrichia with papular lesions (APL) is a rare inherited disease characterized by early onset of total hair loss, followed by papular lesions over the extensor areas of the body. Recently, mutations in the human hairless (HR) gene have been implicated in its pathogenesis. The identification of mutations in the HR gene is important for differentiating between APL and alopecia universalis (AU). OBJECTIVE We compared the HR genes of patients with presumed AU who showed minimal or no response to treatment with the HR genes of healthy controls. METHODS The subjects were 11 patients with presumed AU who had not responded to treatments. Fifty healthy people were included as controls for molecular analysis. To screen for mutations, polymerase chain reaction was performed. RESULTS DNA analysis identified a novel heterozygous G-to-A transition at nucleotide position 191 in exon 5. The mutation was not found in the controls, other AU patients, or any unaffected family members except for the patients' mother and maternal grandfather, who were heterozygous HR gene carriers. CONCLUSION Our study identifies a novel missense mutation in exon 5 of the HR gene in a Korean APL patient previously diagnosed as AU.
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Affiliation(s)
- Deborah Lee
- Department of Dermatology, Busan Paik Hospital, College of Medicine, Inje University, Busan, Korea
| | - Sang-Hyun Kim
- Department of Dermatology, Busan Paik Hospital, College of Medicine, Inje University, Busan, Korea
| | - Ji-Sung Chun
- Department of Dermatology, Busan Paik Hospital, College of Medicine, Inje University, Busan, Korea
| | - Myeong-Hoon Joo
- Graduate School of Molecular & Biomedical Technology, Inje University, Gimhae, Korea
| | - Ji-Yeon Kim
- College of General Education, Inje University, Gimhae, Korea
| | - Seon-Wook Hwang
- Department of Dermatology, Busan Paik Hospital, College of Medicine, Inje University, Busan, Korea
| | | | | | - Ho-Suk Sung
- Department of Dermatology, Busan Paik Hospital, College of Medicine, Inje University, Busan, Korea
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Redler S, Kruse R, Eigelshoven S, Hanneken S, Refke M, Wen Y, Zhang X, Cichon S, Betz RC, Nöthen MM. Marie Unna hereditary hypotrichosis: Identification of a U2HR mutation in the family from the original 1925 report. J Am Acad Dermatol 2011; 64:e45-50. [DOI: 10.1016/j.jaad.2010.06.013] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2010] [Revised: 05/11/2010] [Accepted: 06/09/2010] [Indexed: 11/30/2022]
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AZEEM Z, WASIF N, BASIT S, RAZAK S, WAHEED RA, ISLAM A, AYUB M, KAFAITULLAH, KAMRAN-UL-HASSAN NAQVI S, ALI G, AHMAD W. Congenital atrichia with papular lesions resulting from novel mutations in human hairless gene in four consanguineous families. J Dermatol 2011; 38:755-60. [DOI: 10.1111/j.1346-8138.2010.01151.x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
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Wasif N, Naqvi SKUH, Basit S, Ali N, Ansar M, Ahmad W. Novel mutations in the keratin-74 (KRT74) gene underlie autosomal dominant woolly hair/hypotrichosis in Pakistani families. Hum Genet 2010; 129:419-24. [PMID: 21188418 DOI: 10.1007/s00439-010-0938-9] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2010] [Accepted: 12/19/2010] [Indexed: 10/18/2022]
Abstract
Autosomal dominant woolly hair (ADWH) is an inherited condition of tightly curled and twisted scalp hair. Recently, a mutation in human keratin-74 (KRT74) gene has been shown to cause this form of hereditary hair disorder. In the present study, we have described two families (A and B) having multiple individuals affected with autosomal dominant form of hair loss disorders. In family A, 10 individuals showed ADWH phenotype while in the family B, 14 individuals showed hypotrichosis of the scalp. Genotyping using polymorphic microsatellite markers showed linkage of both the families to type II keratin gene cluster on the chromosome 12q12-14.1. Mutation analysis of the KRT74 gene identified two novel mutations in the affected individuals of the families. The sequence analysis revealed a splice acceptor site mutation (c.IVS8-1G>A) in family A and a missense variant (c.1444G>A, p.Asp482Asn) in family B. Mutations identified in the present study extend the body of evidence implicating the KRT74 gene in the pathogenesis of autosomal dominant hair loss disorders.
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Affiliation(s)
- Naveed Wasif
- Department of Biochemistry, Faculty of Biological Sciences, Quaid-i-Azam University, Islamabad, Pakistan
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Affiliation(s)
- Yutaka Shimomura
- Department of Dermatology, Columbia University, New York, NY 10032
| | - Angela M. Christiano
- Department of Dermatology, Columbia University, New York, NY 10032
- Department of Genetics and Development, Columbia University, New York, NY 10032;
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Hsieh JC, Slater SA, Whitfield GK, Dawson JL, Hsieh G, Sheedy C, Haussler CA, Haussler MR. Analysis of hairless corepressor mutants to characterize molecular cooperation with the vitamin D receptor in promoting the mammalian hair cycle. J Cell Biochem 2010; 110:671-86. [PMID: 20512927 DOI: 10.1002/jcb.22578] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
The mammalian hair cycle requires both the vitamin D receptor (VDR) and the hairless (Hr) corepressor, each of which is expressed in the hair follicle. Hr interacts directly with VDR to repress VDR-targeted transcription. Herein, we further map the VDR-interaction domain to regions in the C-terminal half of Hr that contain two LXXLL-like pairs of motifs known to mediate contact of Hr with the RAR-related orphan receptor alpha and with the thyroid hormone receptor, respectively. Site-directed mutagenesis indicates that all four hydrophobic motifs are required for VDR transrepression by Hr. Point mutation of rat Hr at conserved residues corresponding to natural mutants causing alopecia in mice (G985W and a C-terminal deletion DeltaAK) and in humans (P95S, C422Y, E611G, R640Q, C642G, N988S, D1030N, A1040T, V1074M, and V1154D), as well as alteration of residues in the C-terminal Jumonji C domain implicated in histone demethylation activity (C1025G/E1027G and H1143G) revealed that all Hr mutants retained VDR association, and that transrepressor activity was selectively abrogated in C642G, G985W, N988S, D1030N, V1074M, H1143G, and V1154D. Four of these latter Hr mutants (C642G, N988S, D1030N, and V1154D) were found to associate normally with histone deacetylase-3. Finally, we identified three regions of human VDR necessary for association with Hr, namely residues 109-111, 134-201, and 202-303. It is concluded that Hr and VDR interact via multiple protein-protein interfaces, with Hr recruiting histone deacetylases and possibly itself catalyzing histone demethylation to effect chromatin remodeling and repress the transcription of VDR target genes that control the hair cycle.
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Affiliation(s)
- Jui-Cheng Hsieh
- Department of Basic Medical Sciences, University of Arizona College of Medicine, Phoenix, Arizona 85004, USA.
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Dowd DR, MacDonald PN. The 1,25-dihydroxyvitamin D3-independent actions of the vitamin D receptor in skin. J Steroid Biochem Mol Biol 2010; 121:317-21. [PMID: 20362670 PMCID: PMC4127032 DOI: 10.1016/j.jsbmb.2010.03.072] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/19/2009] [Revised: 03/23/2010] [Accepted: 03/25/2010] [Indexed: 11/28/2022]
Abstract
The vitamin D endocrine system plays important but poorly understood roles in the skin and in hair follicle cycling. Rare, human genetic disorders and knockout mouse models highlight essential roles and potentially novel mechanisms of the vitamin D endocrine system in the skin. Vitamin D receptor knockout mice express a hair follicle cycling defect and a hyperproliferative phenotype resulting in disordered skin structure, epidermal thickening, and alopecia. In contrast, ligand knockout mice (i.e., mice with a disrupted CYP27B1 gene that encodes the 25-hydroxyvitamin-D3 1alpha-hydroxylase) have normal hair follicle function and a comparatively modest skin phenotype. These disparate models indicate that VDR may function independently of 1,25-dihydroxyvitamin D3 (1,25(OH)2D3) in regulating hair follicle cycling and skin biology. Recent studies highlight this concept and provide key support for this hypothesis. While VDR knockout mice are highly susceptible to chemically induced skin tumorigenesis, CYP27B1 knockouts are resistant. These studies reveal a second global physiological process in the skin that may be regulated by VDR in a 1,25(OH)2D3-independent fashion, namely, genoprotection against carcinogenic mutagens. Key cellular and molecular data supporting this mechanism were published recently showing a keratinocyte-selective transactivation activity mediated by VDR that is independent of the 1,25(OH)2D3 ligand. Thus, evidence is building to support a potentially novel, 1,25(OH)2D3-independent mechanism through which VDR functions in keratinocytes and perhaps within stem cell populations in the follicle to regulate genoprotection and other key developmental processes in the skin.
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26
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Basit S, Ali G, Wasif N, Ansar M, Ahmad W. Genetic mapping of a novel hypotrichosis locus to chromosome 7p21.3-p22.3 in a Pakistani family and screening of the candidate genes. Hum Genet 2010; 128:213-20. [PMID: 20544222 DOI: 10.1007/s00439-010-0847-y] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2010] [Accepted: 06/01/2010] [Indexed: 11/30/2022]
Abstract
Hereditary hypotrichosis is a heterogeneous group of inherited hair loss disorders characterized by diffused or localized thinning or absence of hair affecting scalp, eyebrows and eyelashes, and other body parts. Over the past few years, at least four autosomal dominant and six autosomal recessive forms of hypotrichosis have been described. All these ten forms of hypotrichosis have been mapped on different human chromosomes and the corresponding genes have been identified in most of these cases. In the present study, we have described a six-generation Pakistani consanguineous family with an autosomal recessive transmission of hereditary hypotrichosis. All the five affected individuals of the family showed complete absence of scalp hair and sparse eyebrows and eyelashes. They were born with complete absence of scalp hairs. Facial hair of beard and mustaches were present in all the affected adult male individuals. Papules were observed only on scalp of the affected individuals. A scalp biopsy from an affected individual showed markedly reduced number of hair follicles. Human genome scan using polymorphic microsatellite markers mapped the disease locus on chromosome 7p21.3-p22.3, flanked by markers D7S1532 and D7S3047. A maximum two-point LOD score of 4.74 (theta = 0.00) was obtained at marker D7S481. The linkage interval spans 15.69 cM, which corresponds to 6.59 Mb according to the sequence-based physical map (Build 36.2). Mutation analysis of five potential candidate genes (GNA12, FOXK1, DAGLB, ZNF12, ACTB), located in the linkage interval, did not reveal any functional sequence variant.
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Affiliation(s)
- Sulman Basit
- Department of Biochemistry, Faculty of Biological Sciences, Quaid-i-Azam University, Islamabad, Pakistan
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28
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Hamill KJ, Langbein L, Jones JCR, McLean WHI. Identification of a novel family of laminin N-terminal alternate splice isoforms: structural and functional characterization. J Biol Chem 2010; 284:35588-96. [PMID: 19773554 PMCID: PMC2790989 DOI: 10.1074/jbc.m109.052811] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The laminins are a family of heterotrimeric basement membrane proteins that play roles in cellular adhesion, migration, and tissue morphogenesis. Through in silico analysis of the laminin-encoding genes, we identified a novel family of alternate splice isoforms derived from the 5'-end of the LAMA3 and LAMA5 genes. These isoforms resemble the netrins in that they contain a laminin N-terminal domain followed by a short stretch of laminin-type epidermal growth factor-like repeats. We suggest the terms LaNt (laminin N terminus) alpha3 and LaNt alpha5, for the predicted protein products of these mRNAs. RT-PCR confirmed the presence of these transcripts at the mRNA level. Moreover, they exhibit differential, tissue-specific, expression profiles. To confirm the existence of LaNt alpha3 protein, we generated an antibody to a unique domain within the putative polypeptide. This antibody recognizes a protein at the predicted molecular mass of 64 kDa by immunoblotting. Furthermore, immunofluorescence analyses revealed a basement membrane staining in epithelial tissue for LaNt alpha3 and LaNt alpha3 localized along the substratum-associated surface of cultured keratinocytes. We have also tested the functionality LaNt alpha3 through RNAi-mediated knockdown. Keratinocytes exhibiting specific knockdown of LaNt alpha3 displayed impaired adhesion, stress resistance, and reduced ability to close scratch wounds in vitro.
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Affiliation(s)
- Kevin J Hamill
- Epithelial Genetics Group, Human Genetics Unit, Division of Pathology and Neuroscience, Ninewells Hospital and Medical School, University of Dundee, Dundee DD1 9SY, Scotland, United Kingdom.
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Thompson CC. Hairless is a nuclear receptor corepressor essential for skin function. NUCLEAR RECEPTOR SIGNALING 2009; 7:e010. [PMID: 20087431 PMCID: PMC2807636 DOI: 10.1621/nrs.07010] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/20/2009] [Accepted: 12/11/2009] [Indexed: 12/25/2022]
Abstract
The activity of nuclear receptors is modulated by numerous coregulatory factors. Corepressors can either mediate the ability of nuclear receptors to repress transcription, or can inhibit transactivation by nuclear receptors. As we learn more about the mechanisms of transcriptional repression, the importance of repression by nuclear receptors in development and disease has become clear. The protein encoded by the mammalian Hairless (Hr) gene was shown to be a corepressor by virtue of its functional similarity to the well-established corepressors N-CoR and SMRT. Mutation of the Hr gene results in congenital hair loss in both mice and men. Investigation of Hairless function both in vitro and in mouse models in vivo has revealed a critical role in maintaining skin and hair by regulating the differentiation of epithelial stem cells, as well as a putative role in regulating gene expression via chromatin remodeling.
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30
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Betz R. Genetik der monogenen isolierten Alopezien. MED GENET-BERLIN 2009. [DOI: 10.1007/s11825-009-0200-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Zusammenfassung
Die monogen vererbten isolierten Alopezien umfassen eine Gruppe klinisch und genetisch heterogener Formen von Haarlosigkeit/-verlust. Die klinische Unterteilung der isolierten Alopezien erfolgt nach Erkrankungsbeginn, betroffenen Regionen und Struktur des Haarschafts. Frauen und Männer sind gleichermaßen betroffen, die Vererbung ist autosomal-dominant oder autosomal-rezessiv. Seit der Identifizierung des Keratingens KRT86 als Ursache für die so genannte Monilethrix im Jahr 1997 konnten in der letzten Dekade Mutationen in 9 weiteren Genen für verschiedene Formen isolierter Alopezien identifiziert werden, darunter weitere Keratingene (KRT81 und KRT83) für die Monilethrix, das Hairless-Gen für die Atrichia congenita/papuläre Atrichie, das Corneodesmosingen für die autosomal-dominante Form der Hypotrichosis simplex sowie die Gene Desmoglein 4, Lipase H und der G-Protein gekoppelte Rezeptor P2RY5 (LPAR6) für autosomal-rezessive Formen der Hypotrichose. Molekulargenetische und pathophysiologische Untersuchungen dieser seltenen Haarentwicklungsstörungen trugen entscheidend dazu bei, grundlegende Mechanismen des Haarausfalls und somit auch physiologische Mechanismen des Haarwachstums besser zu verstehen.
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Affiliation(s)
- R.C. Betz
- Aff1_200 grid.15090.3d 000000008786803X Institut für Humangenetik, Biomedizinisches Zentrum Universitätsklinikum Bonn AöR Sigmund-Freud-Straße 25 53127 Bonn Deutschland
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31
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Kim JK, Kim E, Baek IC, Kim BK, Cho AR, Kim TY, Song CW, Seong JK, Yoon JB, Stenn KS, Parimoo S, Yoon SK. Overexpression of Hr links excessive induction of Wnt signaling to Marie Unna hereditary hypotrichosis. Hum Mol Genet 2009; 19:445-53. [PMID: 19897589 DOI: 10.1093/hmg/ddp509] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Marie Unna hereditary hypotrichosis (MUHH) is a rare autosomal dominant hair disorder. Through the study of a mouse model, we identified a mutation in the 5'-untranslated region of the hairless (HR) gene in patients with MUHH in a Caucasian family. The corresponding mutation, named 'hairpoor', was found in mutant mice that were generated through N-ethyl-N-nitrosourea mutagenesis. Hairpoor mouse mutants display partial hair loss at an early age and progress to near alopecia, which resembles the MUHH phenotype. This mutation conferred overexpression of HR through translational derepression and, in turn, decreased the expression of Sfrp2, an inhibitor of the Wnt signaling pathway. This study indicates that the gain in function of HR also results in alopecia, as seen with the loss of function of HR, via abnormal upregulation of the Wnt signaling pathway.
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Affiliation(s)
- Jeong-Ki Kim
- Department of Biomedical Sciences, The Catholic University of Korea, 505 Banpo-dong, Seocho-ku, Seoul, Korea
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Malloy PJ, Wang J, Jensen K, Feldman D. Modulation of vitamin d receptor activity by the corepressor hairless: differential effects of hairless isoforms. Endocrinology 2009; 150:4950-7. [PMID: 19819974 PMCID: PMC2775984 DOI: 10.1210/en.2009-0358] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
The vitamin D receptor (VDR) and its corepressor Hairless (HR) are thought to regulate key steps in the hair cycle because mutations in VDR or HR cause alopecia in humans and mice. Many mammalian cells express two major HR isoforms due to alternative splicing of exon 17. HR isoform-a encodes an 1189-amino acid protein (full-length HR), and isoform-b encodes an 1134-amino acid protein (HRDelta1072-1126). We demonstrated that both HR isoforms are expressed in primary human keratinocytes and in the human keratinocyte cell line HaCaT. In transfected COS-7 cells, the full-length HR repressed VDR-mediated transactivation. In contrast, HRDelta1072-1126 failed to suppress and even stimulated VDR-mediated transactivation. In coimmunoprecipitation, both HR isoforms interacted with the VDR, but only the full-length HR interacted with histone deacetylase 1 (HDAC1). Alanine mutagenesis of two conserved glutamic acids residues (E1100A/E1101A) encoded by exon 17 completely eliminated HR corepressor activity and interactions with HDAC1. When the two HR isoforms were coexpressed in COS-7 cells, the corepressor activity of the full-length HR was not antagonized by the HRDelta1072-1126 isoform. When transfected into HaCaT cells, the full-length HR inhibited endogenous CYP24A1 basal gene expression as well as 1,25-dihydroxyvitamin D3-stimulated CYP24A1 expression. HRDelta1072-1126 failed to suppress basal or 1,25-dihydroxyvitamin D3-stimulated CYP24A1 gene expression. In conclusion, we have demonstrated that both HR isoforms are expressed in keratinocytes and that the HRDelta1072-1126 isoform lacks corepressor activity and is unable to bind HDACs. HRDelta1072-1126 may function as a coactivator in some settings by inhibiting HDAC recruitment to the VDR transcriptional complex.
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Affiliation(s)
- Peter J Malloy
- S025 Division of Endocrinology, Gerontology, and Metabolism, Stanford University School of Medicine, 300 Pasteur Drive, Stanford, California 94305-5103, USA.
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Novel missense mutations in lipase H (LIPH) gene causing autosomal recessive hypotrichosis (LAH2). J Dermatol Sci 2009; 54:12-6. [DOI: 10.1016/j.jdermsci.2008.12.001] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2008] [Revised: 11/29/2008] [Accepted: 12/05/2008] [Indexed: 02/04/2023]
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Teichert A, Arnold LA, Otieno S, Oda Y, Augustinaite I, Geistlinger TR, Kriwacki RW, Guy RK, Bikle DD. Quantification of the vitamin D receptor-coregulator interaction. Biochemistry 2009; 48:1454-61. [PMID: 19183053 DOI: 10.1021/bi801874n] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
The vitamin D receptor (VDR) regulates a diverse set of genes that control processes including bone mineral homeostasis, immune function, and hair follicle cycling. Upon binding to its natural ligand, 1alpha,25(OH)(2)D(3), the VDR undergoes a conformational change that allows the release of corepressor proteins and the binding of coactivator proteins necessary for gene transcription. We report the first comprehensive evaluation of the interaction of the VDR with a library of coregulator binding motifs in the presence of two ligands, the natural ligand 1alpha,25(OH)(2)D(3) and a synthetic, nonsecosteroidal agonist LG190178. We show that the VDR has relatively high affinity for the second and third LxxLL motifs of SRC1, SRC2, and SRC3 and second LxxLL motif of DRIP205. This pattern is distinct in comparison to other nuclear receptors. The pattern of VDR-coregulator binding affinities was very similar for the two agonists investigated, suggesting that the biologic functions of LG190178 and 1alpha,25(OH)(2)D(3) are similar. Hairless binds the VDR in the presence of ligand through a LxxLL motif (Hr-1), repressing transcription in the presence and absence of ligand. The VDR binding patterns identified in this study may be used to predict functional differences among different tissues expressing different sets of coregulators, thus facilitating the goal of developing tissue- and gene-specific vitamin D response modulators.
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Affiliation(s)
- Arnaud Teichert
- Endocrine Unit, University of California, San Francisco, San Francisco, California 94121, USA
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Shimomura Y, Wajid M, Zlotogorski A, Lee YJ, Rice RH, Christiano AM. Founder mutations in the lipase h gene in families with autosomal recessive woolly hair/hypotrichosis. J Invest Dermatol 2009; 129:1927-34. [PMID: 19262606 DOI: 10.1038/jid.2009.19] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Autosomal-recessive woolly hair (ARWH)/hypotrichosis is a hereditary hair disorder which is characterized by tightly curled hair and is associated with sparse hair. ARWH can be caused by mutations in the P2RY5 or lipase H (LIPH) gene. Disruption of either gene results in phenotypes with features of both wooly hair (WH) and hypotrichosis. In this study, we identified two Guyanese families with ARWH. Both families are of recent Indian descent. Mutation analysis resulted in the identification of mutations in the LIPH gene in both families. Affected individuals in the first family carry compound heterozygous mutations Ex7_8del and 1303_1309dupGAAAACG in the LIPH gene, while those in the second family have a homozygous mutation 659_660delTA in the LIPH gene. The mutations Ex7_8del and 659_660delTA were identified earlier in several Pakistani families with ARWH. Haplotype analysis using microsatellite markers close to the LIPH gene defined a founder haplotype shared in families from Pakistan and Guyana. Proteomic analysis of hair shaft samples from one of the families revealed no substantial changes among the proteins identified, indicating that the syndrome does not involve global alterations in protein expression. Our results further suggest a crucial role of LIPH gene in hair growth.
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Affiliation(s)
- Yutaka Shimomura
- Department of Dermatology, Columbia University, New York, New York, USA
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Wen Y, Liu Y, Xu Y, Zhao Y, Hua R, Wang K, Sun M, Li Y, Yang S, Zhang XJ, Kruse R, Cichon S, Betz RC, Nöthen MM, van Steensel MAM, van Geel M, Steijlen PM, Hohl D, Huber M, Dunnill GS, Kennedy C, Messenger A, Munro CS, Terrinoni A, Hovnanian A, Bodemer C, de Prost Y, Paller AS, Irvine AD, Sinclair R, Green J, Shang D, Liu Q, Luo Y, Jiang L, Chen HD, Lo WHY, McLean WHI, He CD, Zhang X. Loss-of-function mutations of an inhibitory upstream ORF in the human hairless transcript cause Marie Unna hereditary hypotrichosis. Nat Genet 2009; 41:228-33. [PMID: 19122663 DOI: 10.1038/ng.276] [Citation(s) in RCA: 134] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2008] [Accepted: 10/14/2008] [Indexed: 11/09/2022]
Abstract
Marie Unna hereditary hypotrichosis (MUHH) is an autosomal dominant form of genetic hair loss. In a large Chinese family carrying MUHH, we identified a pathogenic initiation codon mutation in U2HR, an inhibitory upstream ORF in the 5' UTR of the gene encoding the human hairless homolog (HR). U2HR is predicted to encode a 34-amino acid peptide that is highly conserved among mammals. In 18 more families from different ancestral groups, we identified a range of defects in U2HR, including loss of initiation, delayed termination codon and nonsense and missense mutations. Functional analysis showed that these classes of mutations all resulted in increased translation of the main HR physiological ORF. Our results establish the link between MUHH and U2HR, show that fine-tuning of HR protein levels is important in control of hair growth, and identify a potential mechanism for preventing hair loss or promoting hair removal.
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Affiliation(s)
- Yaran Wen
- McKusick-Zhang Center for Genetic Medicine and National Laboratory of Medical Molecular Biology, Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing 100005, China
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Finocchiaro R, Castiglioni B, Budelli E, van Kaam JBCHM, Portolano B, Caroli A, Pagnacco G. Chromosomal assignment of the ovine hairless (hr) gene by fluorescence insitu hybridization. Hereditas 2008; 145:258-61. [PMID: 19076694 DOI: 10.1111/j.1601-5223.2008.02062.x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022] Open
Affiliation(s)
- Raffaella Finocchiaro
- Dipartimento S En Fi Mi Zo-Sezione Produzioni Animali, Università degli Studi di Palermo, Palermo, Italy.
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Finocchiaro R, Castiglioni B, Budelli E, van Kaam JB, Portolano B, Caroli A, Pagnacco G. Chromosomal assignment of the ovinehairless(hr) gene by fluorescenceinsituhybridization. Hereditas 2008. [DOI: 10.1111/j.0018-0661.2008.02062.x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
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Shimomura Y, Garzon MC, Kristal L, Shapiro L, Christiano AM. Autosomal recessive woolly hair with hypotrichosis caused by a novel homozygous mutation in the P2RY5 gene. Exp Dermatol 2008; 18:218-21. [PMID: 18803659 DOI: 10.1111/j.1600-0625.2008.00788.x] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
During the last decade, several causative genes for hereditary hair diseases have been identified, which have disclosed the molecular mechanisms involved in hair follicle morphogenesis and cycling. We and others recently reported that mutations in the P2RY5 gene, encoding an orphan G protein-coupled receptor, underlie autosomal recessive woolly hair (WH)/hypotrichosis. Although these findings clearly reveal the involvement of P2RY5 mutations in hereditary hair diseases, the clinical manifestations of P2RY5 mutations have not completely been elucidated because of limited information to date. In this study, we ascertained a consanguineous family of Iranian origin with an affected girl showing sparse and hypopigmented scalp hair. She exhibited the WH phenotype with normal hair density at birth, but progressed with age to develop hypotrichosis. Direct sequencing analysis resulted in the identification of a novel homozygous mutation in the P2RY5 gene of the patient, which results in a non-conservative amino acid change, G146R, at the protein level. Our findings extend the mutation spectrum of P2RY5 mutations, and further support a crucial role of P2Y5 in hair growth in humans.
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Affiliation(s)
- Yutaka Shimomura
- Department of Dermatology, Columbia University, New York, NY 10032, USA
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Petukhova L, Sousa EC, Martinez-Mir A, Vitebsky A, Dos Santos LG, Shapiro L, Haynes C, Gordon D, Shimomura Y, Christiano AM. Genome-wide linkage analysis of an autosomal recessive hypotrichosis identifies a novel P2RY5 mutation. Genomics 2008; 92:273-8. [PMID: 18692127 DOI: 10.1016/j.ygeno.2008.06.009] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2008] [Revised: 06/13/2008] [Accepted: 06/16/2008] [Indexed: 10/21/2022]
Abstract
While there have been significant advances in understanding the genetic etiology of human hair loss over the previous decade, there remain a number of hereditary disorders for which a causative gene has yet to be identified. We studied a large, consanguineous Brazilian family that presented with woolly hair at birth that progressed to severe hypotrichosis by the age of 5, in which 6 of the 14 offspring were affected. After exclusion of known candidate genes, a genome-wide scan was performed to identify the disease locus. Autozygosity mapping revealed a highly significant region of extended homozygosity (lod score of 10.41) that contained a haplotype with a linkage lod score of 3.28. Results of these two methods defined a 9-Mb region on chromosome 13q14.11-q14.2. The interval contains the P2RY5 gene, in which we recently identified pathogenic mutations in several families of Pakistani origin affected with autosomal recessive woolly and sparse hair. After the exclusion of several other candidate genes, we sequenced the P2RY5 gene and identified a homozygous mutation (C278Y) in all affected individuals in this family. Our findings show that mutations in P2RY5 display variable expressivity, underlying both hypotrichosis and woolly hair, and underscore the essential role of P2RY5 in the tissue integrity and maintenance of the hair follicle.
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Affiliation(s)
- Lynn Petukhova
- Department of Dermatology, Columbia University College of Physicians and Surgeons, New York, NY 10032, USA
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Hahn P, Böse J, Edler S, Lengeling A. Genomic structure and expression of Jmjd6 and evolutionary analysis in the context of related JmjC domain containing proteins. BMC Genomics 2008; 9:293. [PMID: 18564434 PMCID: PMC2453528 DOI: 10.1186/1471-2164-9-293] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2007] [Accepted: 06/18/2008] [Indexed: 12/24/2022] Open
Abstract
Background The jumonji C (JmjC) domain containing gene 6 (Jmjd6, previously known as phosphatidylserine receptor) has misleadingly been annotated to encode a transmembrane receptor for the engulfment of apoptotic cells. Given the importance of JmjC domain containing proteins in controlling a wide range of diverse biological functions, we undertook a comparative genomic analysis to gain further insights in Jmjd6 gene organisation, evolution, and protein function. Results We describe here a semiautomated computational pipeline to identify and annotate JmjC domain containing proteins. Using a sequence segment N-terminal of the Jmjd6 JmjC domain as query for a reciprocal BLAST search, we identified homologous sequences in 62 species across all major phyla. Retrieved Jmjd6 sequences were used to phylogenetically analyse corresponding loci and their genomic neighbourhood. This analysis let to the identification and characterisation of a bi-directional transcriptional unit compromising the Jmjd6 and 1110005A03Rik genes and to the recognition of a new, before overseen Jmjd6 exon in mammals. Using expression studies, two novel Jmjd6 splice variants were identified and validated in vivo. Analysis of the Jmjd6 neighbouring gene 1110005A03Rik revealed an incident deletion of this gene in two out of three earlier reported Jmjd6 knockout mice, which might affect previously described conflicting phenotypes. To determine potentially important residues for Jmjd6 function a structural model of the Jmjd6 protein was calculated based on sequence conservation. This approach identified a conserved double-stranded β-helix (DSBH) fold and a HxDxnH facial triad as structural motifs. Moreover, our systematic annotation in nine species identified 313 DSBH fold-containing proteins that split into 25 highly conserved subgroups. Conclusion We give further evidence that Jmjd6 most likely has a function as a nonheme-Fe(II)-2-oxoglutarate-dependent dioxygenase as previously suggested. Further, we provide novel insights into the evolution of Jmjd6 and other related members of the superfamily of JmjC domain containing proteins. Finally, we discuss possibilities of the involvement of Jmjd6 and 1110005A03Rik in an antagonistic biochemical pathway.
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Affiliation(s)
- Phillip Hahn
- Research Group Infection Genetics, Department of Experimental Mouse Genetics, Helmholtz Centre for Infection Research, D-31824 Braunschweig, Germany.
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Dermatopathology and molecular genetics. J Am Acad Dermatol 2008; 58:452-7. [DOI: 10.1016/j.jaad.2007.12.008] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2007] [Revised: 12/11/2007] [Accepted: 12/12/2007] [Indexed: 11/20/2022]
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G protein-coupled receptor P2Y5 and its ligand LPA are involved in maintenance of human hair growth. Nat Genet 2008; 40:329-34. [PMID: 18297070 DOI: 10.1038/ng.84] [Citation(s) in RCA: 293] [Impact Index Per Article: 18.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2007] [Accepted: 11/27/2007] [Indexed: 01/08/2023]
Abstract
Hypotrichosis simplex is a group of nonsyndromic human alopecias. We mapped an autosomal recessive form of this disorder to chromosome 13q14.11-13q21.33, and identified homozygous truncating mutations in P2RY5, which encodes an orphan G protein-coupled receptor. Furthermore, we identified oleoyl-L-alpha-lysophosphatidic acid (LPA), a bioactive lipid, as a ligand for P2Y5 in reporter gene and radioligand binding experiments. Homology and studies of signaling transduction pathways suggest that P2Y5 is a member of a subgroup of LPA receptors, which also includes LPA4 and LPA5. Our study is the first to implicate a G protein-coupled receptor as essential for and specific to the maintenance of human hair growth. This finding may provide opportunities for new therapeutic approaches to the treatment of hair loss in humans.
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Abstract
Caspase-14 is a unique member of the evolutionarily conserved family of cysteinyl aspartate–specific proteinases, which are mainly involved in inflammation and apoptosis. However, recent evidence also implicates these proteases in proliferation and differentiation. Although most caspases are ubiquitously expressed, caspase-14 expression is confined mainly to cornifying epithelia, such as the skin. Moreover, caspase-14 activation correlates with cornification, indicating that it plays a role in terminal keratinocyte differentiation. The determination of in vitro conditions for caspase-14 activity paved the way to identifying its substrates. The recent development of caspase-14–deficient mice underscored its importance in the correct degradation of (pro)filaggrin and in the formation of the epidermal barrier that protects against dehydration and UVB radiation. Here, we review the current knowledge on caspase-14 in skin homeostasis and disease.
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Affiliation(s)
- Geertrui Denecker
- Department for Molecular Biomedical Research, Flanders Institute for Biotechnology (VIB), 9052 Ghent, Belgium
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Kim H, Wajid M, Kraemer L, Shimomura Y, Christiano AM. Nonsense mutations in the hairless gene underlie APL in five families of Pakistani origin. J Dermatol Sci 2007; 48:207-11. [PMID: 17869066 PMCID: PMC3341169 DOI: 10.1016/j.jdermsci.2007.07.007] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2007] [Revised: 07/13/2007] [Accepted: 07/17/2007] [Indexed: 11/25/2022]
Abstract
BACKGROUND Atrichia with papular lesions (APL) is a rare autosomal recessive form of inherited alopecia. Affected individuals present with a distinct pattern of total hair loss on the scalp, axilla and body shortly after birth and are essentially devoid of eyelashes and eyebrows. This form of hair loss is irreversible and the histology is consistent with an absence of mature hair follicles. In addition to total atrichia, APL patients also present with papules and follicular cysts filled with cornified material. Mutations in the Hairless (HR) gene have been shown to underlie APL. OBJECTIVE Here, we studied five unrelated large Pakistani families with clinical manifestations of APL. METHODS Based on previous reports of HR mutations in APL, we performed direct DNA sequencing analysis. RESULTS DNA sequencing of the HR gene in APL patients revealed three novel nonsense mutations in five unrelated families. All affected individuals were homozygous for a nonsense mutation due to C-to-T transitions at different positions in the amino acid sequence. Two families carry the mutation Q323X (CAG-TAG) in exon 3, two families harbor the mutation Q502X (CAG-TAG) in exon 6, and one family had a mutation at R940X (CGA-TGA) in exon 14. Haplotype analysis revealed that all affected individuals of both APL1 and APL16 families were homozygous for the same haplotype, and likewise, the mutation in families APL2 and APL19 was on the same haplotype. CONCLUSIONS We report three novel nonsense mutations in the HR gene in APL. Two of the newly identified mutations, Q323X and Q502X, were found to be shared between unrelated families and marker analysis confirmed an identical homozygous haplotype for APL1 and APL16, and for APL2 and APL19. These findings suggest that Q323X and Q502X did not arise independently, but instead appear to have been propagated in the population. Collectively, these findings contribute further evidence for the involvement of hairless mutations in papular atrichia.
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Affiliation(s)
- Hyunmi Kim
- Department of Dermatology, Columbia University, New York, NY
| | - Muhammad Wajid
- Department of Dermatology, Columbia University, New York, NY
| | - Liv Kraemer
- Department of Dermatology, Columbia University, New York, NY
| | | | - Angela M. Christiano
- Department of Dermatology, Columbia University, New York, NY
- Department of Genetics and Development, Columbia University, New York, NY
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Michailidis E, Theos A, Zlotogorski A, Martinez-Mir A, Christiano AM. Atrichia with papular lesions resulting from novel compound heterozygous mutations in the human hairless gene. Pediatr Dermatol 2007; 24:E79-82. [PMID: 17958788 DOI: 10.1111/j.1525-1470.2007.00448.x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Atrichia with papular lesions is a rare form of complete, irreversible alopecia that is inherited in an autosomal recessive manner. Several studies have implicated mutations in the human hairless gene as the underlying cause of this disorder. We describe two novel heterozygous mutations in exons 3 and 8 of the hairless gene in a 2-year-old Caucasian boy with complete alopecia of his scalp. These novel mutations add to the growing literature of mutations in the hairless gene found in nonconsanguineous families and expands the allelic series of mutations in this gene.
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Affiliation(s)
- Eleni Michailidis
- College of Dental Medicine, Columbia University, New York, New York, USA
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Wang J, Malloy PJ, Feldman D. Interactions of the Vitamin D Receptor with the Corepressor Hairless. J Biol Chem 2007; 282:25231-9. [PMID: 17609203 DOI: 10.1074/jbc.m702939200] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Atrichia with papular lesions (APL) and hereditary vitamin D-resistant rickets have a similar congenital hair loss disorder caused by mutations in hairless (HR) and vitamin D receptor (VDR) genes, respectively. HR is a VDR corepressor, and it has been hypothesized that VDR.HR suppress gene expression during specific phases of the hair cycle. In this study, we examined the corepressor activity of HR mutants (E583V, C622G, N970S, V1056M, D1012N, V1136D, and Q1176X) previously described as the molecular cause of APL as well as HR variants (P69S, C397Y, A576V, E591G, R620Q, T1022A) due to non-synonymous polymorphisms in the HR gene. We found that the corepressor activities of all but one of the pathogenic HR mutants were completely abolished. HR mutant E583V exhibited normal corepressor activity, suggesting that it may not be pathogenic. In co-immunoprecipitation assays, all of the pathogenic HR mutants bound VDR but exhibited reduced binding to histone deacetylase 1 (HDAC1), suggesting that the impaired corepressor activity is due in part to defective interactions with HDACs. The HR variants exhibited two classes of corepressor activity, those with normal activity (C397Y, E591G, R620Q) and those with partially reduced activity (P69S, A576V, T1022A). All of the variants interacted with VDR and HDAC1 with the exception of P69S, which was degraded. When coexpressed with VDR, all of the HR pathogenic mutants and variants increased the level of VDR protein, demonstrating that this function of HR was not impaired by these mutations. This study of HR mutations provides evidence for the molecular basis of APL.
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Affiliation(s)
- Jining Wang
- Division of Endocrinology, Gerontology, and Metabolism, Department of Medicine, Stanford University School of Medicine, Stanford, California 94305-5103, USA
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