Hairless Gene Research Articles

Novel pathogenic variants in HR underlie atrichia with papular lesions in a cohort of 10 families.

Atrichia with papular lesions (APL) is a hair abnormality characterized by loss of hair on the scalp and rest of the body. In a few cases, hair loss is accompanied by the appearance of keratotic papules on the body. It is inherited in an autosomal recessive manner. Sequence variants in the HR (hairless) gene are responsible for this hair abnormality. Here, we present nine consanguineous families and one nonconsanguineous family with clinical manifestations of APL. Whole exome followed by Sanger sequencing and/or direct Sanger sequencing was performed to identify pathogenic variants. The study revealed seven novel pathogenic variants c.794del;p.(Pro265Argfs*98), c.2921-2936del;p.(Tyr974Leufs*16), c.2889C>A;p.(Cys963*), c.2689C>T;p.(Gln897*), c.3186_3187dup;p.(Gln1063Profs*43), c.560dup;p.(Tyr188Ilefs*131), c.2203+5G>C, c.2776+5G>A, and the previously reported variant c.1837C>T;p.(Arg613*) in HR in these families. The study not only expands the mutational spectrum in the HR gene but also highlights the unusual phenotypic findings and will facilitate genetic counseling of families with members showing various types of hair loss disorders in the local population.

Congenital Atrichia: A Case Report

Introduction: Congenital Atrichia is a rare genetic condition in which all body hair may be absent. Congenital Atrichia is a rare genodermatoses is characterized by a mutation of the human hairless (HR) gene on chromosome 8p22. There is loss of scalp hair between, eyebrow, eyelash, and body hair may also be sparse or absent; patients may have a few pubic and axillary hairs. The condition may present in isolation or along with other defects. There are many forms of inherited alopecia (i.e., hair loss), which vary in age of onset, severity, and associated ectodermal abnormalities. Congenital alopecia universalis or congenital atrichia without associated ectodermal defects is a rare autosomal recessive disorder and is the only form of inherited alopecia for which the molecular basis is known. (2) Case Report: Here is a case report on a preterm neonate delivered via normal vaginal delivery in our hospital setup. Patient was on mechanical ventilator after birth. Patient gradually improved at it was noticed that there was total absence of hair on the body. Dermatology opinion was taken and after few investigations and genetic testing it was confirmed case of Congenital Atrichia due to mutation in chromosome no 8p22. Discussion: Congenital atrichia is a rare disease, causing irreversible alopecia which is inherited autosomal recessively. There is complete irreversible hair loss seen soon after birth. Situs inversus and mesocardia has also been reported to be associated with this disease. Conclusion: Congenital atrichias represent a large and heterogeneous group of inherited hair disorders. In this report, we describe a patient affected with alopecia universalis congenita Keywords: Congenital, atrichia, hairless gene, vitamin d deficiency

The Histone Demethylase HR Suppresses Breast Cancer Development through Enhanced CELF2 Tumor Suppressor Activity.

Simple SummaryWe performed targeted sequencing to identify somatic mutations at the hairless (HR) gene locus in human breast tumors. We found HR mutations in approximately 15% of the patient cohort (n = 85), compared with 23% for BRCA2, 13% for GATA3, 7% for BRCA1, and 3% for PTEN in the same breast cancer patient cohort. We also found an average 23% HR copy number loss in breast cancers. HR reconstitution in HR-deficient human breast cancer cells significantly suppressed tumor growth in orthotopic xenograft mouse models. We further demonstrated that HR’s antitumor activity was at least partly mediated by transcriptional activation of CELF2, a tumor suppressor with RNA-binding activity. Finally, we showed that pharmacologic inhibition of histone methylation is effective in suppressing HR-deficient breast tumor growth and progression. These findings suggest that HR loss plays an important role in breast cancer pathogenesis and will lead to future studies to explore specific inhibitors of HR-dependent histone methylation pathway to abrogate HR-deficient tumor growth and progression.The hairless (HR) gene encodes a transcription factor with histone demethylase activity that is essential for development and tissue homeostasis. Previous studies suggest that mutational inactivation of HR promotes tumorigenesis. To investigate HR mutations in breast cancer, we performed targeted next-generation sequencing using DNA isolated from primary breast cancer tissues. We identified HR somatic mutations in approximately 15% of the patient cohort (n = 85), compared with 23% for BRCA2, 13% for GATA3, 7% for BRCA1, and 3% for PTEN in the same patient cohort. We also found an average 23% HR copy number loss in breast cancers. In support of HR’s antitumor functions, HR reconstitution in HR-deficient human breast cancer cells significantly suppressed tumor growth in orthotopic xenograft mouse models. We further demonstrated that HR’s antitumor activity was at least partly mediated by transcriptional activation of CELF2, a tumor suppressor with RNA-binding activity. Consistent with HR’s histone demethylase activity, pharmacologic inhibition of histone methylation suppressed HR-deficient breast cancer cell proliferation, migration and tumor growth. Taken together, we identified HR as a novel tumor suppressor that is frequently mutated in breast cancer. We also showed that pharmacologic inhibition of histone methylation is effective in suppressing HR-deficient breast tumor growth and progression.

A rare cause of irrevocable childhood alopecia feigning alopecia universalis: Atrichia congenita with papular lesions

Atrichia congenita with papular lesions is rare, autosomal recessive condition that leads to complete hairloss which is irreversible and with keratin filled papular lesions. An insertion mutation in the exon 2 of hairless gene is responsible for the hairloss. Middle and lower portions of hair follicle are replaced by keratinizing cysts with absence of hair shafts. We here by reporting a case of 8-year-old girl with complete hairloss over scalp, eyebrows, eyelashes, and body which started at birth and complete hairloss was gradual by 9 months age on view of its rarity and misdiagnosis.

Triiodothyronine Treatment reverses Depression-Like Behavior in a triple-transgenic animal model of Alzheimer's Disease.

Alzheimer disease's (AD) is a neurodegenerative disorder characterized by cognitive and behavioral impairment. The central nervous system is an important target of thyroid hormones (TH). An inverse association between serum triiodothyronine (T3) levels and the risk of AD symptoms and progression has been reported. We investigated the effects of T3 treatment on the depression-like behavior in male transgenic 3xTg-AD mice. Animals were divided into 2 groups treated with daily intraperitoneal injections of 20 ng/g of body weight (b.w.) L-T3 (T3 group) or saline (vehicle, control group). The experimental protocol lasted 21 days, and behavioral tests were conducted on days 18-20. At the end of the experiment, the TH profile and hippocampal gene expression were evaluated. The T3-treated group significantly increased serum T3 and decreased thyroxine (T4) levels. When compared to control hippocampal samples, the T3 group exhibited attenuated glycogen synthase kinase-3 (GSK3), metalloproteinase 10 (ADAM10), amyloid-beta precursor-protein (APP), serotonin transporter (SERT), 5HT1A receptor, monocarboxylate transporter 8 (MCT8) and bone morphogenetic protein 7 (BMP-7) gene expression, whereas augmented superoxide dismutase 2 (SOD2) and Hairless gene expression. T3-treated animals also displayed reduced immobility time in both the tail suspension and forced swim tests, and in the latter presented a higher latency time compared to the control group. Therefore, our findings suggest that in an AD mouse model, T3 supplementation promotes improvements in depression-like behavior, through the modulation of the serotonergic related genes involved in the transmission mediated by 5HT1A receptors and serotonin reuptake, and attenuated disease progression.

Abstract P3-05-04: The histone demethylase hairless functions as a tumor suppressor gene in breast cancer development

Abstract The hairless (HR) gene encodes a transcription factor with histone demethylase activity that is essential for development and tissue homeostasis. Previous studies suggest that HR possesses antitumor activity in skin cancer models. Surveying human cancer genomics datasets identified frequent HR missense mutations or deletions in various human malignancies including breast cancers, suggesting that HR might function as a tumor suppressor in cancer development. By targeted sequencing, we identified HR mutations in approximately 29% of human breast cancer tissues (n=85), compared to 33% for BRCA2 and 17% for BRCA1 in the same sample cohort. Digital PCR assays also revealed frequent HR copy number loss across breast cancer subtypes. To further define HR’s putative tumor suppressor function in breast cancer and its mechanism of action, we reconstituted HR expression in HR-deficient human breast cancer cells. HR re-expression significantly suppressed tumor growth and metastasis in orthotopic xenograft mouse models. This antitumor activity of HR in breast cancer cells was partly associated with transcriptional activation of the CELF2 tumor suppressor gene, a new HR-regulated gene identified by RNA-seq studies. Consistent with HR’s H3K9 demethylase activity, pharmacological inhibition of H3K9 methylation inhibited HR-deficient breast cancer cell proliferation and migration. Taken together, these studies demonstrate that HR is a novel tumor suppressor, and pharmacological inhibition of H3K9 methylation may be explored to reduce HR-deficient breast cancer cell growth and survival. methylation inhibited HR-deficient breast cancer cell proliferation and migration in vitro, and tumor growth and metastasis in xenograft models. Taken together, these studies suggest that HR is a novel tumor suppressor, and pharmacological inhibition of H3K9 methylation may be explored to treat HR-deficient breast cancers. Citation Format: Liang Liu, Yao Shen, Jasvinder Singh, Bindy Sah, Zhongming Chen, Christine Henzler, Wootae Ha, Tao Su, Hanina Hibshoosh. The histone demethylase hairless functions as a tumor suppressor gene in breast cancer development [abstract]. In: Proceedings of the 2021 San Antonio Breast Cancer Symposium; 2021 Dec 7-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2022;82(4 Suppl):Abstract nr P3-05-04.

Hairless regulates heterochromatin maintenance and muscle stem cell function as a histone demethylase antagonist

Skeletal muscle possesses remarkable regenerative ability because of the resident muscle stem cells (MuSCs). A prominent feature of quiescent MuSCs is a high content of heterochromatin. However, little is known about the mechanisms by which heterochromatin is maintained in MuSCs. By comparing gene-expression profiles from quiescent and activated MuSCs, we found that the mammalian Hairless (Hr) gene is expressed in quiescent MuSCs and rapidly down-regulated upon MuSC activation. Using a mouse model in which Hr can be specifically ablated in MuSCs, we demonstrate that Hr expression is critical for MuSC function and muscle regeneration. In MuSCs, loss of Hr results in reduced trimethylated Histone 3 Lysine 9 (H3K9me3) levels, reduced heterochromatin, increased susceptibility to genotoxic stress, and the accumulation of DNA damage. Deletion of Hr leads to an acceleration of the age-related decline in MuSC numbers. We have also demonstrated that despite the fact that Hr is homologous to a family of histone demethylases and binds to di- and trimethylated H3K9, the expression of Hr does not lead to H3K9 demethylation. In contrast, we show that the expression of Hr leads to the inhibition of the H3K9 demethylase Jmjd1a and an increase in H3K9 methylation. Taking these data together, our study has established that Hr is a H3K9 demethylase antagonist specifically expressed in quiescent MuSCs.

Autozygosity Mapping by Genome-wide Single Nucleotide Polymorphism Array Identifies a Novel Homozygous HR Mutation in a Consanguineous Family with Universal Hereditary Hair Loss

AbstractObjective:Isolated hereditary hypotrichosis is caused by mutations in as many as 11 different genes. The conventional mutation detection strategy consists of sequencing of individual candidate genes separately, a time consuming and costly approach. In this study, we perform genome-wide single nucleotide polymorphism (SNP) array to identify candidate genes of hereditary hypotrichosis.Methods:A consanguineous family with two patients with hereditary hypotrichosis was enrolled, and autozygosity mapping by genome-wide SNP array was utilized to identify candidate genes.Results:Autozygosity mapping delineated runs of homozygosity, and alignment of the 11 genes identified the hairless (HR) gene as the candidate gene. Nucleotide sequencing revealed a novel homozygous mutation c.381delT, p.Ser127ArgfsTer40.Conclusion:This study illustrates how autozygosity mapping by a high-density SNP array streamlines mutation detection in heritable skin diseases.

Relationship of a Novel c.429delC Deletion in Hairless Gene HR with Alopecia in Two Families from Southern Punjab, Pakistan

Relationship of a Novel c.429delC Deletion in Hairless Gene HR with Alopecia in Two Families from Southern Punjab, Pakistan

786 A master regulator function of hairless in skin homeostasis and immune regulation

The hairless (Hr) gene plays an essential role in hair follicle development and skin homeostasis. Both humans and mice lacking hairless activity suffer from complete hair loss and abnormal epidermal proliferation and differentiation, although the mechanisms underlying such developmental defects remain largely unknown. We recently demonstrated that Hr encodes a histone demethylase and acts as an epigenetic regulator of the expression of its target genes. Gene expression profiling studies identified pro-inflammatory IL-1 family cytokines, including IL-36 and IL-1β, among the major targets of Hr.

Papular atrichia

<p>Congenital atrichia or papular atrichia is a rare form of irreversible alopecia inherited autosomal recessively. Atrichia congenita with papular lesions represents a complex and heterogeneous group of genodermatoses characterized by irreversible complete hair loss soon after birth, and associated with the development of keratin-filled cysts over the body. Mutation of the human hairless (HR) gene on chromosome 8p22 has been implicated with this condition. It has broad differential diagnosis and poses diagnostic and therapeutic challenges. We report an 8 year girl presenting with complete loss of hair over scalp, eye brows, eye lashes, and body soon after birth with papular lesions over face.<strong></strong></p>

Identification of a recurrent nonsense mutation in HR gene responsible for atrichia with papular lesions in two Kashmiri families

Congenital atrichia (CA) is a rare form of irreversible alopecia with an autosomal recessive mode of inheritance. This form of hair loss is mainly associated with mutations in the human hairless (HR) gene located at chromosome 8p21.3. An additional unique feature atrichia with papular lesions (APL) comprises keratin-filled cysts known as papules. The present study aimed to uncover the underlying genetic causes of APL in two consanguineous Kashmiri families. In the present study, two consanguineous families of Kashmiri origin with APL displaying an autosomal recessive mode of inheritance were investigated. Whole exome and Sanger sequencing followed by bioinformatic studies, variant prioritization, Sanger validation and segregation analysis was performed to find the mutation. A recurrent nonsense (NM_005144: c.2818C > T:p.Arg940*) mutation was detected in exon 13 of the human HR gene. Whole exome sequencing analysis has widely been used in the screening of single gene disorders mutations, both in research and diagnostic laboratories. Sanger sequencing alone for genes such as HR becomes expensive and time consuming. Instead, it is recommended that a patient is to screen by whole exome sequencing and then special attention first focuses on known genes of the APL phenotype. This is helpful for intime diagnosis, being more efficient and economic. The results obtained in the present study may contribute to prenatal diagnosis, carrier secreening and the genetic counseling of families with the APL phenotype in Kashmiri poplution.

Congenital atrichia with papular lesions

Congenital atrichia with papular lesions is a rare, autosomal recessive and irreversible form of total alopecia of the body hair characterized by hair loss soon after birth and the development of keratinfilled cysts or horny papules over extensive areas of the body. The condition is associated with a mutation of the human hairless gene on chromosome region 8p12. We report a 1-year-old boy presenting with the absence of scalp and body hair since birth. On examination, he had complete absence of hair on the scalp, eyebrows, and eyelashes. Multiple, discrete, pearly-to-skin-colored papules of 1-3mm in size were present over the scalp. The skin biopsy from a scalp papule revealed normal overlying epidermis with multiple keratin cysts and hypoplastic hair follicles in the upper dermis.

Hairless-knockout piglets generated using the clustered regularly interspaced short palindromic repeat/CRISPR-associated-9 exhibit abnormalities in the skin and thymus.

The nuclear receptor corepressor Hairless (HR) interacts with nuclear receptors and controls expression of specific target genes involved in hair morphogenesis and hair follicle cycling. Patients with HR gene mutations exhibit atrichia, and in rare cases, immunodeficiency. Pigs with HR gene mutations may provide a useful model for developing therapeutic strategies because pigs are highly similar to humans in terms of anatomy, genetics, and physiology. The present study aimed to knockout the HR gene in pigs using the clustered regularly interspaced short palindromic repeat (CRISPR)/CRISPR-associated-9 (Cas9) system and to investigate the molecular and structural alterations in the skin and thymus. We introduced a biallelic mutation into the HR gene in porcine fetal fibroblasts and generated nine piglets via somatic cell nuclear transfer. These piglets exhibited a lack of hair on the eyelids, abnormalities in the thymus and peripheral blood, and altered expression of several signaling factors regulated by HR. Our results indicate that introduction of the biallelic mutation successfully knocked out the HR gene, resulting in several molecular and structural changes in the skin and thymus. These pigs will provide a useful model for studying human hair disorders associated with HR gene mutations and the underlying molecular mechanisms.

Hairless regulates p53 target genes to exert tumor suppressive functions in glioblastoma.

Glioblastoma (GBM) is the most common malignant brain tumor and is associated with a poor prognosis, with most patients living less than a year after diagnosis. Given that GBM nearly always recurs after conventional treatments, there is an urgent need to identify novel molecular targets. Hairless (HR) is a nuclear factor enriched in the skin and has been previously implicated in hair cycling. HR is also highly expressed in the brain, but its significance is unknown. We found that human hairless gene (HR) expression is significantly decreased in all GBM subtypes compared with normal brain tissue and is predictive of prognosis, which suggests that loss of HR expression can contribute to GBM pathogenesis. HR was recently discovered to bind to and regulate p53 responsive elements, and thus we hypothesized that HR may have a tumor suppressive function in GBM by modulating p53 target gene expression. We found that HR indeed regulates p53 target genes, including those implicated in cell cycle progression and apoptosis in the GBM-derived U87 cell line, and restoring HR expression triggered G2/M arrest and apoptosis. An analysis of sequenced genomes from patients with GBM revealed 10 HR somatic mutations in patients with glioma, two of which are located in the histone demethylase domain of HR. These two mutations, P996S and K1004N, were reconstructed and found to have impaired p53 transactivating properties. Collectively, the results of our study suggest that HR has tumor suppressive functions in GBM, which may be clinically relevant and a potential avenue for therapeutic intervention.

Conservation of the Notch antagonist Hairless in arthropods: functional analysis of the crustacean Daphnia pulex Hairless gene.

The Notch signaling pathway is highly conserved in all animal metazoa: upon Notch receptor activation, transcription of Notch target genes is turned on by an activator complex that centers on the transcription factor CSL. In the absence of signal, CSL assembles transcriptional repression complexes that display remarkable evolutionary diversity. The major antagonist of Notch signaling in insects named Hairless was originally identified in Drosophila melanogaster. It binds to the Drosophila CSL homologue Suppressor of Hairless [Su(H)] and recruits the two general co-repressors, Groucho and C-terminal binding protein. Whereas the majority of Notch signaling components is conserved between insects and vertebrates, Hairless is found only in insects. Here, we present the analysis of the Hairless gene from Daphnia pulex and, hence, for the first time from a crustacean. Daphnia and Drosophila Hairless protein sequences are highly diverged. Known functional domains, however, the Su(H), Groucho and the C-terminal binding protein interactions domains, are well conserved. Moreover, direct binding of the Daphnia Hairless protein and the respective Drosophila interaction partners was detected, demonstrating the conservation at the molecular level. In addition, interaction between Daphnia Hairless and Drosophila Su(H) was demonstrated in vivo, as co-overexpression of the respective genes during Drosophila development resulted in the expected downregulation of Notch activity in the fly. Structural models show that the Hairless-Su(H) repressor complexes from Daphnia and Drosophila are almost indistinguishable from one another. Amino acid residues in direct contact within the Hairless-Su(H) complex are at absolutely identical positions in the two homologues.

Hairless controls hair fate decision via Wnt/β–catenin signaling

The hairless (Hr) gene plays a central role in the hair cycle, considering that mutations in the gene result in hair loss with the exception of a few vibrissae after the first hair growth cycle in both mice and humans. This study examinedthe uncommon phenotype and using microarray analyses and functional studies, we found that β-catenin was mediated by Hr. Progenitor keratinocytes from the bulge region differentiate into both epidermis and sebaceous glands, and fail to adopt the hair keratinocytes fate in the mutant scalp, due to the decreased Wnt/β-catenin signaling in the absence of the hairless protein. This may be attributed to the dysfunction of normal epithelial-mesenchymal interactions in the hair follicle (HF).

Human Hairless Protein Roles in Skin/Hair and Emerging Connections to Brain and Other Cancers.

The mammalian hairless protein (HR) is a 130 kDa nuclear transcription factor that is essential for proper skin and hair follicle function. Previous studies have focused on the role of HR in skin maintenance and hair cycling. However, the hairless gene (HR) is also expressed in brain and other tissues, where its role remains poorly understood. HR has been reported to contain functional domains that potentially serve in DNA binding, histone demethylation, nuclear translocation and protein-protein interactions. Indeed, HR has been shown to interact with and repress the action of the nuclear receptors for vitamin D and thyroid hormone as well as RAR-related orphan receptor alpha, possibly via recruitment of histone deacetylases. HR may also have important functions in non-skin tissues given that nearly 200 HR mutations have been identified in patients with various cancers, including prostate, breast, lung, melanoma, uterine, and glioma. This suggests that HR and/or mutants thereof have relevance to the growth and survival of cancer cells. For example, the reported intrinsic histone H3K9 demethylase activity of HR may activate dormant genes to contribute to carcinogenesis. Alternatively, the demonstrated ability of HR to interact with p53 and/or the p53 DNA response element to influence p53-regulated pathways may explain, at least in part, why many cancers express mutated HR proteins. In this review, we summarize the current knowledge of HR bioactions, how HR mutations may be contributing to alopecia as well as to cancer, and, finally, outline future directions in the study of this largely enigmatic nuclear protein. J. Cell. Biochem. 119: 69-80, 2018. © 2017 Wiley Periodicals, Inc.

Application of hairless mouse strain to bioluminescence imaging of Arc expression in mouse brain

BackgroundBioluminescence imaging (BLI) is a powerful technique for monitoring the temporal and spatial dynamics of gene expression in the mouse brain. However, the black fur, skin pigmentation and hair regrowth after depilation of mouse interfere with BLI during developmental and daily examination. The aim of this study was to extend the application of Arc-Luc transgenic (Tg) mice to the BLI of neuronal activity in the mouse brain by introducing the hairless (HL) gene and to examine Arc-Luc expression at various developmental stages without interference from black fur, skin pigmentation, and hair regrowth.ResultsThe Arc-Luc Tg HL mice were established by crossing the Tg C57BL/6 mouse strain with the HL mouse strain. Under physiological and pathological conditions, BLI was performed to detect the signal intensity changes at various developmental stages and at an interval of <7 days. The established Arc-Luc Tg HL mice exhibited clear and stable photon signals from the brain without interference during development. After surgical monocular deprivation during visual-critical period, large signal intensity changes in bioluminescence were observed in the mouse visual cortex. Exposure of mice to a novel object changed the photon distribution in the caudal and rostral cerebral areas. The temporal pattern of kainic-acid-induced Arc-Luc expression showed biphasic changes in signal intensity over 24 h.ConclusionsThis study showed the advantages of using the mutant HL gene in BLI of Arc expression in the mouse brain at various developmental stages. Thus, the use of the Arc-Luc Tg HL mice enabled the tracking of neuronal-activity-dependent processes over a wide range from a focal area to the entire brain area with various time windows.

Transgenic mice display hair loss and regrowth overexpressing mutant Hr gene.

Mutations in the hairless (Hr) gene in both mice and humans have been implicated in the development of congenital atrichia, but the role of Hr in skin and hair follicle (HF) biology remains unknown. Here, we established transgenic mice (TG) overexpressing mutant Hr to investigate its specific role in the development of HF. Three transgenic lines were successfully constructed, and two of them (TG3 and TG8) displayed a pattern of hair loss and regrowth with alternation in the expression of HR protein. The mutant Hr gene inhibited the expression of the endogenous gene in transgenic individuals, which led to the development of alopecia. Interestingly, the hair regrew with the increase in the endogenous expression levels resulting from decreased mutant Hr expression. The findings of our study indicate that the changes in the expression of Hr result in hair loss or regrowth.