Mutations in Three Genes Encoding Proteins Involved in Hair Shaft Formation Cause Uncombable Hair Syndrome

Study on the expression patterns of inner root sheath-specific genes in Tan sheep hair follicle during different developmental stages

By analyzing the expression patterns of inner root sheath (IRS) specific genes during different developmental stages of hair follicle (HF) in Tan sheep embryos and at birth, this study aims to reveal the influence of the IRS on crimped wool. Skin tissues from the scapular region of male Tan sheep were collected at 85 days (E85) and 120 days (E120) of fetal development, and at 0 days (D0), 35 days (D35), and 60 days (D60) after birth, with four samples at each stage. Real-time quantitative polymerase chain reaction (RT-qPCR) was employed to determine the relative expression levels of IRS type I keratin genes (KRT25, KRT26, KRT27, KRT28), type II keratin genes (KRT71, KRT72, KRT73, KRT74), and the trichohyalin gene (TCHH) in the skin of Tan sheep at different stages. Results showed that the expression levels of all IRS-specific genes peaked at D0, with the expression of all genes significantly higher than at E85 (P < 0.01), except for KRT73 and TCHH. The expression levels of KRT25, KRT26, and KRT72 were also significantly higher than at E120 (P < 0.01). Furthermore, the expression levels of KRT27, KRT28, KRT71, and KRT74 were significantly higher than both at E120 and D35 (P < 0.01). The expression levels of other genes at different stages showed no significant difference (P > 0.05). Conclusion: The IRS-specific genes exhibit the highest expression levels in Tan sheep at the neonatal stage. The expression levels of KRT71, KRT72, and TCHH, which are consistent with the pattern of wool crimp, may influence the morphology of the IRS and thereby affect the crimp of Tan sheep wool.

Genome-Wide Association Study Identifies Genes for Hair Growth and Patterning are Associated With Pilonidal Disease

BACKGROUND

Pilonidal sinus disease is a highly morbid condition characterized by the formation of chronic sinus tracts throughout the sacrococcygeal region. Despite its commonality and strong association with family history, no prior investigation of genetic risk factors for pilonidal sinus disease exists.

OBJECTIVE

To identify genetic risk factors for pilonidal sinus disease.

DESIGN

A genome-wide association study.

SETTINGS

The United Kingdom Biobank, FinnGen Biobank, and Penn Medicine BioBank.

PATIENTS

There were 772,072 participants.

MAIN OUTCOME MEASURE

Genome-wide significant variants ( p < 5 × 10 -8 ) were mapped to genes using physical distance and gene expression in skin. Genetic correlation between pilonidal sinus disease and morphometric, androgen-driven, and hair phenotypes was estimated with linkage disequilibrium score regression. Finally, a genome-first approach to rare predicted deleterious variants in hair shaft genes TCHH , PADI3 , and TGM3 was conducted for association with pilonidal sinus disease via the Penn Medicine BioBank.

RESULTS

A genome-wide association study comprising 2835 individuals with pilonidal sinus disease identified 5 genome-wide significant loci, prioritizing HDAC9, TBX15, WARS2, RP11-293M10.1 , PRKAR1B , TWIST1, GPATCH2L, NEK9 , and EIF2B2 , as putative causal genes; several of these genes have known roles in balding and hair patterning. There was a significant correlation between the genetic background of pilonidal sinus disease and the androgen-driven hair traits of male pattern baldness and young age at first facial hair. In a candidate analysis of genes associated with syndromic hair disorders, rare coding variants in TCHH , a monogenic cause of uncombable hair syndrome, were associated with increased prevalence of pilonidal sinus disease (OR 4.81 [95% CI, 2.06-11.2]).

LIMITATIONS

This study is limited to European ancestry. However, because there is a higher incidence of pilonidal sinus disease in men of European ancestry, this analysis is focused on the at-risk population.

CONCLUSIONS

Genetic analysis of pilonidal sinus disease identified shared genetic architecture with hair biology and androgen-driven traits. As the first study investigating the genetic basis of pilonidal sinus disease, this provides biological insight into the long-appreciated connection between the disease state, male sex, and hair. See Video abstract.

UN ESTUDIO DE ASOCIACIN DEL GENOMA COMPLETO IDENTIFICA GENES DEL CRECIMIENTO Y EL PATRN DEL PELO ASOCIADOS A LA ENFERMEDAD PILONIDAL

ANTECEDENTES:La enfermedad del seno pilonidal es una condición muy mórbida caracterizada por la formación de tractos sinusales crónicos en toda la región sacrococcígea. A pesar de su frecuencia y su fuerte asociación con los antecedentes familiares, no se han investigado previamente los factores de riesgo genéticos de la enfermedad sinusal pilonidal.OBJETIVO:Identificar factores genéticos de riesgo para la enfermedad del seno pilonidal.DISEÑO:Estudio de asociación de genoma completo.CONJUNTOS:Biobanco del Reino Unido, Biobanco FinnGen y Biobanco PennMedicine.PACIENTES:772.072 participantes.MEDIDA DE RESULTADO PRINCIPAL:Las variantes significativas en todo el genoma (p < 5x10-8) se asignaron a genes utilizando la distancia física y la expresión génica en la piel. La correlación genética entre la enfermedad del seno pilonidal y los fenotipos morfométricos, androgénicos y de cabello se estimó con regresión de puntuación LD. Por último, se realizó una aproximación genómica a variantes deletéreas raras predichas en los genes del tallo piloso TCHH, PADI3 y TGM3 para su asociación con la enfermedad del seno pilonidal a través del Biobanco PennMedicine.RESULTADOS:El estudio de asociación de todo el genoma, que incluyó a 2.835 individuos con enfermedad del seno pilonidal, identificó 5 loci significativos en todo el genoma, dando prioridad a HDAC9, TBX15, WARS2, RP11-293M10.1, PRKAR1B, TWIST1, GPATCH2L, NEK9 y EIF2B2, como genes causales putativos; varios de estos genes tienen funciones conocidas en la calvicie y el patrón del cabello. Se observó una correlación significativa entre los antecedentes genéticos de la enfermedad del seno pilonidal y los de los rasgos calvicie de patrón masculino y edad temprana del primer vello facial impulsados por andrógenos. En un análisis de genes candidatos asociados a trastornos capilares sindrómicos, las variantes raras de codificación en TCHH, una causa monogénica del síndrome capilar incombustible, se asociaron a una mayor prevalencia de la enfermedad del seno pilonidal (OR 4,81 [IC del 5%, 2,06-11,2]).LIMITACIONES:Este estudio se limita a la ascendencia europea. Sin embargo, debido a que hay una mayor incidencia de la enfermedad sinusal pilonidal en los hombres de ascendencia europea, este análisis se centra en la población de riesgo.CONCLUSIÓN:El análisis genético de la enfermedad del seno pilonidal identificó una arquitectura genética compartida con la biología del cabello y los rasgos impulsados por andrógenos. Siendo el primer estudio que investiga las bases genéticas de la enfermedad del seno pilonidal, esto proporciona una visión biológica de la conexión, apreciada desde hace tiempo, entre el estado de la enfermedad, el sexo masculino y el cabello. (Traducción-Dr. Aurian Garcia Gonzalez ).

Two siblings with uncombable hair syndrome: A new pathogenic variant

Two siblings presented with straw-colored, frizzy, and wiry hair. They had no associated abnormalities and no family history of abnormal hair. Trichoscopy showed the longitudinal groove in the hair shafts, characteristic of uncombable hair syndrome. Molecular genetic analysis revealed a new pathogenic variant (c.1374dup; p. Val459ArgfsTer15) in PADI3, not previously described.

The Evolution of Transglutaminases Underlies the Origin and Loss of Cornified Skin Appendages in Vertebrates

Transglutaminases (TGMs) cross-link proteins by introducing covalent bonds between glutamine and lysine residues. These cross-links are essential for epithelial cornification which enables tetrapods to live on land. Here, we investigated which evolutionary adaptations of vertebrates were associated with specific changes in the family of TGM genes. We determined the catalog of TGMs in the main clades of vertebrates, performed a comprehensive phylogenetic analysis of TGMs, and localized the distribution of selected TGMs in tissues. Our data suggest that TGM1 is the phylogenetically oldest epithelial TGM, with orthologs being expressed in the cornified teeth of the lamprey, a basal vertebrate. Gene duplications led to the origin of TGM10 in stem vertebrates, the origin of TGM2 in jawed vertebrates, and an increasing number of epithelium-associated TGM genes in the lineage leading to terrestrial vertebrates. TGM9 is expressed in the epithelial egg tooth, and its evolutionary origin in stem amniotes coincided with the evolution of embryonic development in eggs that are surrounded by a protective shell. Conversely, viviparous mammals have lost both the epithelial egg tooth and TGM9. TGM3 and TGM6 evolved as regulators of cornification in hair follicles and underwent pseudogenization upon the evolutionary loss of hair in cetaceans. Taken together, this study reveals the gain and loss of vertebrate TGM genes in association with the evolution of cornified skin appendages and suggests an important role of TGM9 in the evolution of amniotes.

Burden of Mendelian disorders in a large Middle Eastern biobank

BACKGROUND

Genome sequencing of large biobanks from under-represented ancestries provides a valuable resource for the interrogation of Mendelian disease burden at world population level, complementing small-scale familial studies.

METHODS

Here, we interrogate 6045 whole genomes from Qatar-a Middle Eastern population with high consanguinity and understudied mutational burden-enrolled at the national Biobank and phenotyped for 58 clinically-relevant quantitative traits. We examine a curated set of 2648 Mendelian genes from 20 panels, annotating known and novel pathogenic variants and assessing their penetrance and impact on the measured traits.

RESULTS

We find that 62.5% of participants are carriers of at least 1 known pathogenic variant relating to recessive conditions, with homozygosity observed in 1 in 150 subjects (0.6%) for which Peninsular Arabs are particularly enriched versus other ancestries (5.8-fold). On average, 52.3 loss-of-function variants were found per genome, 6.5 of which affect a known Mendelian gene. Several variants annotated in ClinVar/HGMD as pathogenic appeared at intermediate frequencies in this cohort (1-3%), highlighting Arab founder effect, while others have exceedingly high frequencies (> 5%) prompting reconsideration as benign. Furthermore, cumulative gene burden analysis revealed 56 genes having gene carrier frequency > 1/50, including 5 ACMG Tier 3 panel genes which would be candidates for adding to newborn screening in the country. Additionally, leveraging 58 biobank traits, we systematically assess the impact of novel/rare variants on phenotypes and discover 39 candidate large-effect variants associating with extreme quantitative traits. Furthermore, through rare variant burden testing, we discover 13 genes with high mutational load, including 5 with impact on traits relevant to disease conditions, including metabolic disorder and type 2 diabetes, consistent with the high prevalence of these conditions in the region.

CONCLUSIONS

This study on the first phase of the growing Qatar Genome Program cohort provides a comprehensive resource from a Middle Eastern population to understand the global mutational burden in Mendelian genes and their impact on traits in seemingly healthy individuals in high consanguinity settings.

TCHH as a Novel Prognostic Biomarker for Patients with Gastric Cancer by Bioinformatics Analysis

Background

This study aims to investigate the clinicopathological significance and prognostic value of Trichohyalin (TCHH) in gastric cancer patients through bioinformatics analysis.

Materials and Methods

Data on TCHH expression and clinicopathological information were sourced from The Cancer Genome Atlas (TCGA). The Wilcoxon signed-rank test was used for evaluating the correlation between TCHH mRNA expression levels and clinicopathological features. The predictive significance of TCHH mRNA expression for overall survival (OS), disease-specific survival (DSS), and progression-free interval (PFI) in patients with gastric cancer was assessed using Cox regression models. Furthermore, measures of immune cell infiltration in gastric cancer were made, and studies of gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment were also carried out to investigate the possible roles of TCHH in patients with gastric cancer.

Results

Compared to normal tissues, gastric cancer had a considerably higher expression of TCHH mRNA (P < 0.05). Wilcoxon analysis revealed a significant association between TCHH mRNA expression and the pathologic M stage (P = 0.017). High TPMT mRNA levels were also correlated with worse OS, DFS, and PFI in gastric cancer patients (both P < 0.05). TCHH showed significant negative correlations with the levels of NK CD56dim infiltration (r = -0.157, p = 0.002), Th17 cells infiltration (r = -0.235, P < 0.001), and Th2 infiltration (r = -0.195, P < 0.001). Furthermore, enrichment analysis indicated potential involvement in intermediate filament cytoskeleton organization, DNA methylation in gamete generation, cell-cell recognition, and G protein-coupled peptide receptor (GPCRs) activity.

Conclusion

The level of TCHH mRNA may serve as a novel prognostic biomarker for gastric cancer patients.

Comparative genomics of monotremes provides insights into the early evolution of mammalian epidermal differentiation genes

The function of the skin as a barrier against the environment depends on the differentiation of epidermal keratinocytes into highly resilient corneocytes that form the outermost skin layer. Many genes encoding structural components of corneocytes are clustered in the epidermal differentiation complex (EDC), which has been described in placental and marsupial mammals as well as non-mammalian tetrapods. Here, we analyzed the genomes of the platypus (Ornithorhynchus anatinus) and the echidna (Tachyglossus aculeatus) to determine the gene composition of the EDC in the basal clade of mammals, the monotremes. We report that mammal-specific subfamilies of EDC genes encoding small proline-rich proteins (SPRRs) and late cornified envelope proteins as well as single-copy EDC genes such as involucrin are conserved in monotremes, suggesting that they have originated in stem mammals. Monotremes have at least one gene homologous to the group of filaggrin (FLG), FLG2 and hornerin (HRNR) in placental mammals, but no clear one-to-one pairwise ortholog of either FLG, FLG2 or HRNR. Caspase-14, a keratinocyte differentiation-associated protease implicated in the processing of filaggrin, is encoded by at least 3 gene copies in the echidna. Our results reveal evolutionarily conserved and clade-specific features of the genetic regulation of epidermal differentiation in monotremes.

Investigating the cell membrane localization of PADI4 in breast cancer cells and inhibition of anti-PADI4 monoclonal antibody

BACKGROUND

Peptidyl arginine deiminase 4 (PADI4) is a post-translational modification enzymecan that converts arginine in protein into citrulline in the presence of calcium ions, which is called citrullination. PADI4 has been reported to be expressed in the cytoplasm and nucleus in a variety of malignant tumors. Based on the GeneCards database and our previous research, it is speculated that PADI4 may also be expressed on the cell membrane. This study aimed to confirm the membrane expression of PADI4 and the effect of anti-PADI4 antibodies on cell membrane PADI4. This may be another mechanism of action of anti-PADI4 monoclonal antibodies in the treatment of breast cancer.

METHODS

The subcellular localizations of PADI4 in MDA-MB-231 and MCF-7 breast cancer cells were determined by immunofluorescence, immunoelectron microscopy, and Western blot analysis. The tumor cells were treated with PADI4 antibody, and cell proliferation, migration, colony formation, apoptosis, glycolysis, and epithelial-mesenchymal transition (EMT) were measured as well as the expression of some essential tumor genes.

RESULTS

PADI4 was not only localized in the nucleus and cytoplasm of breast cancer cells but was also detected on the cell membrane. Following PADI4 antibody treatment, cell proliferation, migration, colony formation, EMT, and ATP production through glycolysis were decreased, and the mRNA expression of MYC proto-oncogene (MYC), FAT atypical cadherin 1 (FAT1), nuclear factor kappa B subunit 1 (NFκB), and tumor necrosis factor (TNF-α) in breast cancer cells was downregulated, while the mRNA expression of tumor protein p63 (TP63) was upregulated.

CONCLUSIONS

PADI4 is expressed on the cell membrane in breast cancer cells. Anti-PADI4 antibodies can affect the biological functions of cell membrane PADI4, including proliferation, migration, apoptosis, and glycolysis, thereby inhibiting tumor progression.

Co-expression of PADI isoforms during progenitor differentiation enables functional diversity

Protein isoforms, generated through alternative splicing or promoter usage, contribute to tissue function. Here, we characterize the expression of predicted Padi3α and Padi3β isoforms in hair follicles and describe expression of Padi2β, a hitherto unknown PADI2 isoform, in the oligodendrocyte lineage. Padi2β transcription is initiated from a downstream intronic promoter, generating an N-terminally truncated, unstable, PADI2β. By contrast to the established role of the canonical PADI2 (PADI2α) (Falcao et al. 2019 Cell Rep. 27, 1090-1102.e10. (doi:10.1016/j.celrep.2019.03.108)), PADI2β inhibits oligodendrocyte differentiation, suggesting that PADI2 isoforms exert opposing effects on oligodendrocyte lineage progression. We localize Padi3α and Padi3β to developing hair follicles and find that both transcripts are expressed at low levels in progenitor cells, only to increase in expression concomitant with differentiation. When expressed in vitro, PADI3α and PADI3β are enriched in the cytoplasm and precipitate together. Whereas PADI3β protein stability is low and PADI3β fails to induce protein citrullination, we find that the enzymatic activity and protein stability of PADI3α is reduced in the presence of PADI3β. We propose that PADI3β modulates PADI3α activity by direct binding and heterodimer formation. Here, we establish expression and function of Padi2 and Padi3 isoforms, expanding on the mechanisms in place to regulate citrullination in complex tissues. This article is part of the Theo Murphy meeting issue 'The virtues and vices of protein citrullination'.

Deimination in epidermal barrier and hair formation

Peptidylarginine deiminases (PADs) transform a protein arginine residue into the non-standard amino acid citrulline. This calcium-dependent post-translational modification of proteins is called citrullination or deimination. As described in this special issue, PADs play a role in various physiological processes, and PAD deregulations are involved in many human diseases. Three PADs are expressed in the epidermis, where their roles begin to be deciphered. PAD1 and PAD3 are involved in keratinocyte differentiation, particularly in the epidermal barrier function, keratins, filaggrin and filaggrin-related proteins being the most abundant deiminated epidermal proteins. Reduced amounts of deiminated proteins and PAD1 expression may be involved in the pathogenesis of psoriasis and atopic dermatitis, two very frequent and chronic skin inflammatory diseases. The trichohyalin/PAD3/transglutaminase three pathway is important for hair shaft formation. Mutations of the PADI3 gene, leading to a decreased activity or abnormal localization of the corresponding isotype, are the cause of a rare hair disorder called uncombable hair syndrome, and are associated with the central centrifugal cicatricial alopecia, a frequent alopecia mainly affecting women of African ancestry. This article is part of the Theo Murphy meeting issue 'The virtues and vices of protein citrullination'.

Short anagen hair syndrome: association with mono- and biallelic variants in WNT10A and a genetic overlap with male pattern hair loss

BACKGROUND

Short anagen hair (SAH) is a rare paediatric hair disorder characterized by a short anagen phase, an inability to grow long scalp hair and a negative psychological impact. The genetic basis of SAH is currently unknown.

OBJECTIVES

To perform molecular genetic investigations in 48 individuals with a clinical phenotype suggestive of SAH to identify, if any, the genetic basis of this condition.

METHODS

Exome sequencing was performed in 27 patients diagnosed with SAH or with a complaint of short, nongrowing hair. The cohort was screened for variants with a minor allele frequency (MAF) < 5% in the general population and a Combined Annotation Dependent Depletion (CADD) score > 15, to identify genes whose variants were enriched in this cohort. Sanger sequencing was used for variant validation and screening of 21 additional individuals with the same clinical diagnosis and their relatives. Genetic association testing of SAH-related variants for male pattern hair loss (MPHL) was performed using UK Biobank data.

RESULTS

Analyses revealed that 20 individuals (42%) carried mono- or biallelic pathogenic variants in WNT10A. Rare WNT10A variants are associated with a phenotypic spectrum ranging from no clinical signs to severe ectodermal dysplasia. A significant association was found between WNT10A and SAH, and this was mostly observed in individuals with light-coloured hair and regression of the frontoparietal hairline. Notably, the most frequent variant in the cohort [c.682T>A;p.(Phe228Ile)] was in linkage disequilibrium with four common WNT10A variants, all of which have a known association with MPHL. Using UK Biobank data, our analyses showed that c.682T>A;p.(Phe228Ile) and one other variant identified in the SAH cohort are also associated with MPHL, and partially explain the known associations between WNT10A and MPHL.

CONCLUSIONS

Our results suggest that WNT10A is associated with SAH and that SAH has a genetic overlap with the common phenotype MPHL. The presumed shared biologic effect of WNT10A variants in SAH and MPHL is a shortening of the anagen phase. Other factors, such as modifier genes and sex, may also play a role in the clinical manifestation of hair phenotypes associated with the WNT10A locus.

Identification of MKI67, TPR , and TCHH Mutations as Prognostic Biomarkers for Patients With Defective Mismatch Repair Colon Cancer Stage II/III

BACKGROUND

Stage II/III disease is the most predominant form of colorectal cancer, accounting for approximately 70% of cases. Furthermore, approximately 15% to 20% of patients with stage II/III disease have deficient mismatch repair or microsatellite instability-high colorectal cancer. However, there are no identified significant prognostic biomarkers for this disease.

OBJECTIVE

To identify prognostic markers for patients with deficient mismatch repair/microsatellite instability-high colon cancer stage II/III.

DESIGN

Retrospective study design.

SETTING

The study was conducted at a high-volume colorectal center, the Cancer Hospital, Chinese Academy of Medical Sciences.

PATIENTS

Patients diagnosed with stage II/III deficient mismatch repair/microsatellite instability-high colon cancer who underwent curative surgery at the Cancer Hospital at the Chinese Academy of Medical Sciences between July 2015 and November 2018 were included.

MAIN OUTCOME MEASURES

The primary outcome measure was the influence of differentially mutated genes on progression-free survival.

RESULTS

The retrospective deficient mismatch repair/microsatellite instability-high cohort involved 32 patients and The Cancer Genome Atlas-microsatellite instability-high cohort involved 45 patients. Patients with deficient mismatch repair/microsatellite instability-high colon cancer had higher mutational frequencies of MKI67 , TPR , and TCHH than patients with microsatellite stable colon cancer. MKI67 , TPR , TCHH , and gene combination were significantly correlated with prognosis. The biomarker mutation-type colon cancer group had a higher risk of recurrence or death than did the wild-type group. Moreover, biomarker mutation-type tumors had more mutations in the DNA damage repair pathway and tumor mutational burden than did biomarker wild-type tumors.

LIMITATIONS

This study was limited by its retrospective nature.

CONCLUSIONS

MKI67 , TPR , and TCHH may serve as potential diagnostic and prognostic biomarkers for deficient mismatch repair/microsatellite instability-high colon cancer stage II/III.

IDENTIFICACIN DE MUTACIONES MKI, TPR Y TCHH COMO BIOMARCADORES PRONSTICOS PARA PACIENTES CON CNCER DE COLON EN ETAPA II/III CON DEFICIENCIA EN LA REPARACION DE ERRORES DE EMPAREJAMIENTO

ANTECEDENTES:La enfermedad en estadio II/III es la forma más predominante de cáncer colorrectal y representa aproximadamente el 70% de los casos. Además, aproximadamente entre el 15% y el 20% de los pacientes con enfermedad en estadio II/III tienen reparación deficiente de errores de emparejamiento o inestabilidad de microsatélital alta. Sin embargo, no se han identificado biomarcadores pronósticos significativos para esta enfermedad.OBJETIVO:Este estudio tuvo como objetivo identificar marcadores pronósticos para pacientes con cáncer de colon con reparación deficiente de errores de emparejamiento/inestabilidad microsatelital alta en estadio II/III.DISEÑO:Diseño de estudio retrospectivo.ESCENARIO:El estudio se realizó en un centro colorrectal de alto volumen, el Hospital del Cáncer de la Academia China de Ciencias Médicas.PACIENTES:Pacientes diagnosticados con cáncer de colon en estadio II/III con reparación deficiente de errores de emparejamiento o inestabilidad de microsatélital alta que se sometieron a cirugía curativa en el Hospital del Cáncer de la Academia China de Ciencias Médicas entre julio de 2015 y noviembre de 2018.MEDIDAS DE RESULTADO PRINCIPALES:La medida de resultado primaria fue la influencia de los genes con mutaciones diferenciales en la supervivencia libre de progresión.RESULTADOS:La cohorte retrospectiva de reparación deficiente de errores de emparejamiento o inestabilidad de microsatélital alta y la cohorte de inestabilidad microsatelital alta del Atlas del Genoma del Cáncer involucraron a 32 y 45 pacientes, respectivamente. Los pacientes con de reparación deficiente de errores de emparejamiento/inestabilidad microsatélital alta tuvieron frecuencias mutacionales más altas de MKI67 , TPR y TCHH que los pacientes estables de microsatélites. MKI67 , TPR , TCHH , y la combinación de genes se correlacionaron significativamente con el pronóstico. El grupo de cáncer de colon de tipo mutación de biomarcador tenía un mayor riesgo de recurrencia o muerte que el grupo de mutación salvaje. Además, los tumores de tipo mutación de biomarcadores tenían más mutaciones en la vía de reparación del daño del ADN y la carga mutacional del tumor que los tumores de tipo salvaje de biomarcadores.LIMITACIONES:Este estudio estuvo limitado por su naturaleza retrospectiva.CONCLUSIONES:MKI67 , TPR , y TCHH pueden servir como posibles biomarcadores de diagnóstico y pronóstico para cáncer de colon en estadio II/III con reparación deficiente de errores de emparejamiento/inestabilidad microsatélital alta. (Traducción-Dr. Jorge Silva Velazco ).

Pseudogenization of the Hair-Related Genes PADI3 and S100A3 in Cetaceans and Hippopotamus amphibius

Hair-related genes in mammals play important roles in the development and maintenance of hair and other keratinous structures in mammals. The peptidyl arginine deiminase 3 (PADI3) gene encodes an enzyme that catalyzes the conversion of arginine residues to citrulline. The S100 calcium binding protein A3 (S100A3) gene encodes a protein that is highly expressed in the hair cuticle and contains arginine residues that are converted to citrullines by PADI enzymes. In this study, we investigated the pseudogenization events of PADI3 and S100A3 in cetaceans and Hippopotamus amphibius. We found that PADI3 underwent three independent pseudogenization events during cetacean evolution, in baleen whales, toothed cetaceans other than Physeter catodon, and P. catodon. Notably, the entire PADI3 gene is absent in the baleen whales. Pseudogenization of S100A3 occurred independently in cetaceans and H. amphibius. Interestingly, we found that in cetaceans S100A3 underwent pseudogenization before PADI3, suggesting that differential selection pressures were acting on the two genes. Our findings provide valuable insights into the molecular evolution of these genes in cetaceans and hippopotamuses, highlighting their importance for understanding the evolution of hair-related genes.

Analysis of 72,469 UK Biobank exomes links rare variants to male-pattern hair loss

Male-pattern hair loss (MPHL) is common and highly heritable. While genome-wide association studies (GWAS) have generated insights into the contribution of common variants to MPHL etiology, the relevance of rare variants remains unclear. To determine the contribution of rare variants to MPHL etiology, we perform gene-based and single-variant analyses in exome-sequencing data from 72,469 male UK Biobank participants. While our population-level risk prediction suggests that rare variants make only a minor contribution to general MPHL risk, our rare variant collapsing tests identified a total of five significant gene associations. These findings provide additional evidence for previously implicated genes (EDA2R, WNT10A) and highlight novel risk genes at and beyond GWAS loci (HEPH, CEPT1, EIF3F). Furthermore, MPHL-associated genes are enriched for genes considered causal for monogenic trichoses. Together, our findings broaden the MPHL-associated allelic spectrum and provide insights into MPHL pathobiology and a shared basis with monogenic hair loss disorders.

Down-regulation of peptidylarginine deiminase type 1 in reconstructed human epidermis disturbs nucleophagy in the granular layer and affects barrier function

Deimination is a post-translational modification catalyzed by a family of enzymes named peptidylarginine deiminases (PADs). PADs transform arginine residues of protein substrates into citrulline. Deimination has been associated with numerous physiological and pathological processes. In human skin, three PADs are expressed (PAD1-3). While PAD3 is important for hair shape formation, the role of PAD1 is less clear. To decipher the main role(s) of PAD1 in epidermal differentiation, its expression was down-regulated using lentivirus-mediated shRNA interference in primary keratinocytes and in three-dimensional reconstructed human epidermis (RHE). Compared to normal RHEs, down-regulation of PAD1 caused a drastic reduction in deiminated proteins. Whereas proliferation of keratinocytes was not affected, their differentiation was disturbed at molecular, cellular and functional levels. The number of corneocyte layers was significantly reduced, expression of filaggrin and cornified cell envelope components, such as loricrin and transglutaminases, was down-regulated, epidermal permeability increased and trans-epidermal-electric resistance diminished drastically. Keratohyalin granule density decreased and nucleophagy in the granular layer was disturbed. These results demonstrate that PAD1 is the main regulator of protein deimination in RHE. Its deficiency alters epidermal homeostasis, affecting the differentiation of keratinocytes, especially the cornification process, a special kind of programmed cell death.

New genomic insights into the conformation of Lipizzan horses

Conformation traits are important selection criteria in equine breeding, as they describe the exterior aspects of the horse (height, joint angles, shape). However, the genetic architecture of conformation is not well understood, as data of these traits mainly consist of subjective evaluation scores. Here, we performed genome-wide association studies on two-dimensional shape data of Lipizzan horses. Based on this data, we identified significant quantitative trait loci (QTL) associated with cresty neck on equine chromosome (ECA)16 within the MAGI1 gene, and with type, hereby differentiating heavy from light horses on ECA5 within the POU2F1 gene. Both genes were previously described to affect growth, muscling and fatty deposits in sheep, cattle and pigs. Furthermore, we pin-pointed another suggestive QTL on ECA21, near the PTGER4 gene, associated with human ankylosing spondylitis, for shape differences in the back and pelvis (roach back vs sway back). Further differences in the shape of the back and abdomen were suggestively associated with the RYR1 gene, involved in core muscle weakness in humans. Therefore, we demonstrated that horse shape space data enhance the genomic investigations of horse conformation.

Genomics of adaptive evolution in the woolly mammoth

Ancient genomes provide a tool to investigate the genetic basis of adaptations in extinct organisms. However, the identification of species-specific fixed genetic variants requires the analysis of genomes from multiple individuals. Moreover, the long-term scale of adaptive evolution coupled with the short-term nature of traditional time series data has made it difficult to assess when different adaptations evolved. Here, we analyze 23 woolly mammoth genomes, including one of the oldest known specimens at 700,000 years old, to identify fixed derived non-synonymous mutations unique to the species and to obtain estimates of when these mutations evolved. We find that at the time of its origin, the woolly mammoth had already acquired a broad spectrum of positively selected genes, including ones associated with hair and skin development, fat storage and metabolism, and immune system function. Our results also suggest that these phenotypes continued to evolve during the last 700,000 years, but through positive selection on different sets of genes. Finally, we also identify additional genes that underwent comparatively recent positive selection, including multiple genes related to skeletal morphology and body size, as well as one gene that may have contributed to the small ear size in Late Quaternary woolly mammoths.

Uncombable hair syndrome due to maternal uniparental disomy of chromosome 1

Uncombable hair syndrome is a hair shaft condition in which the hair is frizzy, light in color (silver to light brown), and cannot be combed flat. Autosomal dominant (with complete or incomplete penetrance), autosomal recessive, and sporadic cases have been reported. In 2016 causative mutations in three genes were identified for uncombable hair syndrome, all with an autosomal recessive inheritance pattern: PADI3, TGM3, and TCHH. In many cases, however, there is still no molecular diagnosis. Here, we describe a case of autosomal recessive uncombable hair syndrome resulting from maternal uniparental disomy of chromosome 1.

Examining the Effect of Notocactus ottonis Cold Vacuum Isolated Plant Cell Extract on Hair Growth in C57BL/6 Mice Using a Combination of Physiological and OMICS Analyses

The biological and psychological importance of hair is recognized worldwide. Molecules that can promote the activation of hair follicle stem cells and the initiation of the growth phase have been subjects of research. Clarifying how hair regeneration is regulated may help to provide hair loss treatments, including cosmetic and even psychological interventions. We examined the hair-growing effects of a cell extract (CE) obtained from cactus Notocactus ottonis by the cold vacuum extraction protocol, by investigating its hair-growing effects, relevant mechanisms, and potential factors therein. Using male C57BL/6 mice, vehicle control (VC: propylene glycol: ethanol: water), MXD (minoxidil, positive control), and N. ottonis CE (N-CE, experimental) were applied topically to the backs of mice. The results showed that MXD and N-CE were more effective in promoting hair growth than VC. An increase in number of hair follicles was observed with N-CE in hematoxylin-eosin-stained skin tissue. The metabolite composition of N-CE revealed the presence of growth-promoting factors. Using mouse back whole-skin tissue samples, whole-genome DNA microarray (4 × 44 K, Agilent) and proteomics (TMT-based liquid chromatography-tandem mass spectrometry) analyses were carried out, suggesting the molecular factors underlying hair-promoting effects of N-CE. This study raises the possibility of using the newly described N. ottonis CE as a hair-growth-promoting agent.

Transglutaminase Activity Is Conserved in Stratified Epithelia and Skin Appendages of Mammals and Birds

The cross-linking of structural proteins is critical for establishing the mechanical stability of the epithelial compartments of the skin and skin appendages. The introduction of isopeptide bonds between glutamine and lysine residues depends on catalysis by transglutaminases and represents the main protein cross-linking mechanism besides the formation of disulfide bonds. Here, we used a fluorescent labeling protocol to localize the activity of transglutaminases on thin sections of the integument and its appendages in mammals and birds. In human tissues, transglutaminase activity was detected in the granular layer of the epidermis, suprabasal layers of the gingival epithelium, the duct of sweat glands, hair follicles and the nail matrix. In the skin appendages of chickens, transglutaminase activity was present in the claw matrix, the feather follicle sheath, the feather sheath and in differentiating keratinocytes of feather barb ridges. During chicken embryogenesis, active transglutaminase was found in the cornifying epidermis, the periderm and the subperiderm. Transglutaminase activity was also detected in the filiform papillae on the tongue of mice and in conical papillae on the tongue of chickens. In summary, our study reveals that transglutaminase activities are widely distributed in integumentary structures and suggests that transglutamination contributes to the cornification of hard skin appendages such as nails and feathers.

PAD4 and Its Inhibitors in Cancer Progression and Prognosis

The systemic spread of malignancies and the risk of cancer-associated thrombosis are major clinical challenges in cancer therapy worldwide. As an important post-translational modification enzyme, peptidyl arginine deiminase 4 (PAD4) could mediate the citrullination of protein in different components (including nucleus and cytoplasm, etc.) of a variety of cells (tumor cells, neutrophils, macrophages, etc.), thus participating in gene regulation, neutrophil extracellular trap (NET) and macrophage extracellular trap (MET). Thereby, PAD4 plays an important role in enhancing the growth of primary tumors and facilitating the distant metastasis of cancer cells. In addition, it is related to the formation of cancer-associated thrombosis. Therefore, the development of PAD4-specific inhibitors may be a promising strategy for treating cancer, and it may improve patient prognosis. In this review, we describe PAD4 involvement in gene regulation, protein citrullination, and NET formation. We also discuss its potential role in cancer and cancer-associated thrombosis, and we summarize the development and application of PAD4 inhibitors.

Assessment of the Genetic Spectrum of Uncombable Hair Syndrome in a Cohort of 107 Individuals

Importance

Uncombable hair syndrome (UHS) is a rare hair shaft anomaly that manifests during infancy and is characterized by dry, frizzy, and wiry hair that cannot be combed flat. Only about 100 known cases have been reported so far.

Objective

To elucidate the genetic spectrum of UHS.

Design, Setting, and Participants

This cohort study includes 107 unrelated index patients with a suspected diagnosis of UHS and family members who were recruited worldwide from January 2013 to December 2021. Participants of all ages, races, and ethnicities were recruited at referral centers or were enrolled on their own initiative following personal contact with the authors. Genetic analyses were conducted in Germany from January 2014 to December 2021.

Main Outcomes and Measures

Clinical photographs, Sanger or whole-exome sequencing and array-based genotyping of DNA extracted from blood or saliva samples, and 3-dimensional protein modeling. Descriptive statistics, such as frequency counts, were used to describe the distribution of identified pathogenic variants and genotypes.

Results

The genetic characteristics of patients with UHS were established in 80 of 107 (74.8%) index patients (82 [76.6%] female) who carried biallelic pathogenic variants in PADI3, TGM3, or TCHH (ie, genes that encode functionally related hair shaft proteins). Molecular genetic findings from 11 of these 80 individuals were previously published. In 76 (71.0%) individuals, the UHS phenotype were associated with pathogenic variants in PADI3. The 2 most commonly observed PADI3 variants account for 73 (48.0%) and 57 (37.5%) of the 152 variant PADI3 alleles in total, respectively. Two individuals carried pathogenic variants in TGM3, and 2 others carried pathogenic variants in TCHH. Haplotype analyses suggested a founder effect for the 4 most commonly observed pathogenic variants in the PADI3 gene.

Conclusions and Relevance

This cohort study extends and gives an overview of the genetic variant spectrum of UHS based on molecular genetic analyses of the largest worldwide collective of affected individuals, to our knowledge. Formerly, a diagnosis of UHS could only be made by physical examination of the patient and confirmed by microscopical examination of the hair shaft. The discovery of pathogenic variants in PADI3, TCHH, and TGM3 may open a new avenue for clinicians and affected individuals by introducing molecular diagnostics for UHS.

Understanding Mammalian Hair Follicle Ecosystems by Single-Cell RNA Sequencing

Simple Summary

Single-cell sequencing technology can reflect cell population heterogeneity at the single-cell level, leading to a better understanding of the role of individual cells in the microenvironment. Over the past few years, single-cell sequencing technology has not only made more new discoveries in the study of cellular heterogeneity of other rare cells such as stem cells, but has also become the most powerful research method for embryonic development, organ differentiation, cancer occurrence, and cell mapping. In this review, we outline the use of scRNA-seq in hair follicles. In particular, by focusing on landmark studies and the recent discovery of novel subpopulations of hair follicles, we summarize the phenotypic diversity of hair follicle cells and their links to hair follicle morphogenesis. Enhancing our understanding of the progress of hair follicle research will help to elucidate the regulatory mechanisms that determine the fate of different types of cells in the hair follicle, thereby guiding hair loss treatment and hair-producing economic animal breeding research.

Abstract

Single-cell sequencing technology can fully reflect the heterogeneity of cell populations at the single cell level, making it possible for us to re-recognize various tissues and organs. At present, the sequencing study of hair follicles is transiting from the traditional ordinary transcriptome level to the single cell level, which will provide diverse insights into the function of hair follicle cells. This review focuses on research advances in the hair follicle microenvironment obtained from scRNA-seq studies of major cell types in hair follicle development, with a special emphasis on the discovery of new subpopulations of hair follicles by single-cell techniques. We also discuss the problems and current solutions in scRNA-seq observation and look forward to its prospects.

Autocitrullination and Changes in the Activity of Peptidylarginine Deiminase 3 Induced by High Ca2+ Concentrations

Peptidylarginine deiminases (PADs) are enzymes that catalyze the Ca²⁺-dependent conversion of arginine residues into proteins to citrulline residues. Five PAD isozymes have been identified in mammals. Several studies have shown that the active-site pockets of these isozymes are formed when Ca²⁺ ions are properly bound. We previously characterized the structures of PAD3 in six states. Among these, we identified a "nonproductive" form of PAD3 in which the active site was disordered even though five Ca²⁺ ions were bound. This strange structure was probably obtained as a result of either high Ca²⁺ concentration (∼260 mM)-induced denaturation during the crystallization process or high Ca²⁺-concentration-induced autocitrullination. While autocitrullination has been reported in PAD2 and PAD4 for some time, only a single report on PAD3 has been published recently. In this study, we investigated whether PAD3 catalyzes the autocitrullination reaction and identified autocitrullination sites. In addition to the capacity of PAD3 for autocitrullination, the autocitrullination sites increased depending on the Ca²⁺ concentration and reaction time. These findings suggest that some of the arginine residues in the "nonproductive" form of PAD3 would be autocitrullinated. Furthermore, most of the autocitrullinated sites in PAD3 were located near the substrate-binding site. Given the high Ca²⁺ concentration in the crystallization condition, it is likely that Arg372 was citrullinated in the "nonproductive" PAD3 structure, the structure was slightly altered from the active form by citrulline residues, and probably inhibited Ca²⁺-ion binding at the proper position. Following Arg372 citrullination, PAD3 enters an inactive form; however, the Arg372-citrullinated PAD3 are considered minor components in autocitrullinated PAD3 (CitPAD3), and CitPAD3 does not significantly decrease the enzyme activity. Autocitrullination of PAD3 could not be confirmed at the low Ca²⁺ concentrations seen in vivo. Future experiments using cells and animals are needed to verify the effect of Ca²⁺ on the PAD3 structure and functions in vivo.

Prevalence and prognosis of molecularly defined familial hypercholesterolemia in patients with acute coronary syndrome

Background

Familial hypercholesterolemia (FH) can elevate serum low-density lipoprotein cholesterol (LDL-C) levels, which can promote the progression of acute coronary syndrome (ACS). However, the effect of FH on the prognosis of ACS remains unclear.

Methods

In this prospective cohort study, 223 patients with ACS having LDL-C ≥ 135.3 mg/dL (3.5 mmol/L) were enrolled and screened for FH using a multiple-gene FH panel. The diagnosis of FH was defined according to the ACMG/AMP criteria as carrying pathogenic or likely pathogenic variants. The clinical features of FH and the relationship of FH to the average 16.6-month risk of cardiovascular events (CVEs) were assessed.

Results

The prevalence of molecularly defined FH in enrolled patients was 26.9%, and coronary artery lesions were more severe in patients with FH than in those without (Gensini score 66.0 vs. 28.0, respectively; P < 0.001). After lipid lowering, patients with FH still had significantly higher LDL-C levels at their last visit (73.5 ± 25.9 mg/dL vs. 84.7 ± 37.1 mg/dL; P = 0.013) compared with those without. FH increased the incidence of CVEs in patients with ACS [hazard ratio (HR): 3.058; 95% confidence interval (CI): 1.585–5.900; log-rank P < 0.001].

Conclusion

FH is associated with an increased risk of CVEs in ACS and is an independent risk factor for ACS. This study highlights the importance of genetic testing of FH-related gene mutations in patients with ACS.

Disrupted citric acid metabolism inhibits hair growth

Hair follicles (HFs) play an essential role in sustaining a persistent hair growth cycle. The activities of dermal papilla cells (DPCs) and other cells inside the HFs dominate the process of hair growth. However, the detailed molecular mechanisms remain largely unknown. To investigate the role of citric acid (CA) metabolism in hair growth, we evaluated the effect of citrate synthase (CS)-CA axis on hair growth in vivo and in vitro. Mice hair growth was evaluated by morphology and histopathology analysis. The inflammation and apoptosis levels in mice, HFs, and DPCs were detected by immunohistofluorescence, qPCR, ELISA, western blot, and TUNEL assay. Cell proliferation, cell cycle, and cell apoptosis in DPCs were analyzed by real-time cell analysis and flow cytometer. We found that subcutaneous injection of CA in mice caused significant hair growth suppression, skin lesion, inflammatory response, cell apoptosis, and promotion of catagen entry, compared with the saline control, by activating p-p65 and apoptosis signaling in an NLRP3-dependent manner. In cultured human HFs, CA attenuated the hair shaft production and accelerated HF catagen entry by regulating the above-mentioned pathways. Additionally, CA hampered the proliferation rate of DPCs via inducing cell apoptosis and cell cycle arrest. Considering that citrate synthase (CS) is responsible for CA production and is a rate-limiting enzyme of the tricarboxylic acid cycle, we also investigated the role of CS in CA metabolism and hair growth. As expected, knockdown of CS reduced CA production and reversed CA-induced hair growth inhibition, anagen shrink, inflammation, and apoptosis both in HFs and DPCs. Our experiments demonstrated that CS-CA axis serves as an important mediator and might be a potential therapeutic target in hair growth.

The virtues and vices of protein citrullination

The post-translational modification of proteins expands the regulatory scope of the proteome far beyond what is achievable through genome regulation. The field of protein citrullination has seen significant progress in the last two decades. The small family of peptidylarginine deiminase (PADI or PAD) enzymes, which catalyse citrullination, have been implicated in virtually all facets of molecular and cell biology, from gene transcription and epigenetics to cell signalling and metabolism. We have learned about their association with a remarkable array of disease states and we are beginning to understand how they mediate normal physiological functions. However, while the biochemistry of PADI activation has been worked out in exquisite detail in vitro, we still lack a clear mechanistic understanding of the processes that regulate PADIs within cells, under physiological and pathophysiological conditions. This review summarizes and discusses the current knowledge, highlights some of the unanswered questions of immediate importance and gives a perspective on the outlook of the citrullination field.

Reconstructing the epidermal proteolytic cascades in health and disease

The epidermis is the outer stratified epithelium of the skin, forming the physical barrier that is indispensable for homeostasis. Epidermal proteolysis, mainly but not exclusively executed by kallikrein-related peptidases (KLKs), is tightly regulated to ensure maintenance of physiological skin renewal and an intact skin barrier. Perturbation of epidermal proteolytic networks is implicated in a wide array of rare and common skin pathologies of diverse genetic backgrounds. Recent studies of monogenic human skin diseases and newly developed animal models have revealed new mechanisms of regulation of proteolytic pathways in epidermal physiology and in disease states. These new data have challenged some accepted views, for example the role of matriptase in epidermal desquamation, which turned out to be restricted to mouse skin. The significance of PAR2 signaling in skin inflammation should also be reconsidered in the face of recent findings. Cumulatively, recent studies necessitate a sophisticated redefinition of the proteolytic and signaling pathways that operate in human skin. We elaborate how epidermal proteolysis is finely regulated at multiple levels, and in a spatial manner that was not taken into consideration so far, in which specific proteases are confined to distinct epidermal sublayers. Of interest, transglutaminases have emerged as regulators of epidermal proteolysis and desquamation by spatially fixing endogenous protease inhibitors, constituting regulatory factors that were not recognized before. Furthermore, new evidence suggests a link between proteolysis and lipid metabolism. By synthesis of established notions and recent discoveries, we provide an up-to-date critical parathesis of current knowledge and the extended complexity of proteolysis regulation and signaling pathways in skin. This article is protected by copyright. All rights reserved.

Emerging Roles of Post-Translational Modifications in Skin Diseases: Current Knowledge, Challenges and Future Perspectives

Post-translational modifications (PTMs) of proteins represent as a key step in regulating their biological functions and dynamic interaction with other players. This process is fine-tuned by a myriad of enzymes named “writers, readers and erasers” whose actions are precisely controlled. Either the mutation, aberration in the expression of the aforementioned enzymes or their substrates have shown to participate in the pathogenesis of various skin diseases such as melanoma, vitiligo, psoriasis, eczema, atopic dermatitis and inherited dermatological diseases. It is becoming increasingly clear that key transcriptional factors, inflammation-related molecules are prone to PTMs. Despite their importance in regulating key processes including inflammation, keratinocyte apoptosis, proliferation and differentiation, PTMs have received less attention due to the challenges involved. Here in this review we summarize the role of the most common types and the newly discovered PTMs, including acetylation, glycosylation, citrullination, PARylation and sumoylation in dermatoses and surveys the recent progress in PTM-based therapeutic approaches in skin diseases.

A Hairy Cituation - PADIs in Regeneration and Alopecia

In this Review article, we focus on delineating the expression and function of Peptidyl Arginine Delminases (PADIs) in the hair follicle stem cell lineage and in inflammatory alopecia. We outline our current understanding of cellular processes influenced by protein citrullination, the PADI mediated posttranslational enzymatic conversion of arginine to citrulline, by exploring citrullinomes from normal and inflamed tissues. Drawing from other stem cell lineages, we detail the potential function of PADIs and specific citrullinated protein residues in hair follicle stem cell activation, lineage specification and differentiation. We highlight PADI3 as a mediator of hair shaft differentiation and display why mutations in PADI3 are linked to human alopecia. Furthermore, we propose mechanisms of PADI4 dependent fine-tuning of the hair follicle lineage progression. Finally, we discuss citrullination in the context of inflammatory alopecia. We present how infiltrating neutrophils establish a citrullination-driven self-perpetuating proinflammatory circuitry resulting in T-cell recruitment and activation contributing to hair follicle degeneration. In summary, we aim to provide a comprehensive perspective on how citrullination modulates hair follicle regeneration and contributes to inflammatory alopecia.

Identification of the Key Genes Associated with the Yak Hair Follicle Cycle

The development of hair follicles in yak shows significant seasonal cycles. In our previous research, transcriptome data including mRNAs and lncRNAs in five stages during the yak hair follicles (HFs) cycle were detected, but their regulation network and the hub genes in different periods are yet to be explored. This study aimed to screen and identify the hub genes during yak HFs cycle by constructing a mRNA-lncRNA co-expression network. A total of 5000 differently expressed mRNA (DEMs) and 729 differently expressed long noncoding RNA (DELs) were used to construct the co-expression network, based on weighted genes co-expression network analysis (WGCNA). Four temporally specific modules were considered to be significantly associated with the HFs cycle of yak. Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis revealed that the modules are enriched into Wnt, EMC-receptor interaction, PI3K-Akt, focal adhesion pathways, and so on. The hub genes, such as FER, ELMO1, PCOLCE, and HOXC13, were screened in different modules. Five hub genes (WNT5A, HOXC13, DLX3, FOXN1, and OVOL1) and part of key lncRNAs were identified for specific expression in skin tissue. Furthermore, immunofluorescence staining and Western blotting results showed that the expression location and abundance of DLX3 and OVOL1 are changed following the process of the HFs cycle, which further demonstrated that these two hub genes may play important roles in HFs development.

Cracking the Skin Barrier: Liquid-Liquid Phase Separation Shines under the Skin

Central to forming and sustaining the skin’s barrier, epidermal keratinocytes (KCs) fluxing to the skin surface undergo a rapid and enigmatic transformation into flat, enucleated squames. At the crux of this transformation are intracellular keratohyalin granules (KGs) that suddenly disappear as terminally differentiating KCs transition to the cornified skin surface. Defects in KGs have long been linked to skin barrier disorders. Through the biophysical lens of liquid-liquid phase separation (LLPS), these enigmatic KGs recently emerged as liquid-like membraneless organelles whose assembly and subsequent pH-triggered disassembly drive squame formation. To stimulate future efforts toward cracking the complex process of skin barrier formation, in this review, we integrate the key concepts and foundational work spanning the fields of LLPS and epidermal biology. We review the current progress in the skin and discuss implications in the broader context of membraneless organelles across stratifying epithelia. The discovery of environmentally sensitive LLPS dynamics in the skin points to new avenues for dissecting the skin barrier and for addressing skin barrier disorders. We argue that skin and its appendages offer outstanding models to uncover LLPS-driven mechanisms in tissue biology.

Transglutaminase 2 mediates UVB-induced matrix metalloproteinase-1 expression by inhibiting nuclear p65 degradation in dermal fibroblasts

Matrix metalloproteinases (MMPs) play a key role in tissue remodelling by cleaving extracellular matrix (ECM) components. In the skin, UV irradiation increases expression of MMPs that causes dysregulation of ECM homeostasis in dermis, leading to acceleration of skin aging. However, the mediator(s) that links UV irradiation to the upregulation of MMPs have not been fully defined. Previously, we showed that UVB irradiation activated transglutaminase 2 (TG2) in keratinocytes, eliciting an inflammatory response by activating NF-κB signalling. In this study, we reported the role of TG2 in mediating the UVB-induced expression of MMP-1. In human dermal fibroblasts, UVB irradiation enhanced the expression and activity of TG2, which in turn promotes the expression of MMP-1. Analyses of MMP-1 promoter showed that activation of the NF-κB signalling pathway, rather than AP-1, was responsible for the TG2-mediated upregulation of MMP-1. Moreover, Western blot analysis revealed that TG2 increased the activity of NF-κB by inhibiting degradation of p65 in the nucleus. Furthermore, ex vivo skin from TG2-knockout mice exhibited significantly reduced levels of MMP-1 compared to that from wild-type mice. These results indicate that TG2 functions as a mediator for the UVB-induced expression of MMP-1 in dermal fibroblasts, providing a new target for preventing skin photodamage.

Association analysis for SNPs of KRT26 and TCHH genes with cashmere production performance, body measurement traits and milk production traits in Liaoning cashmere goats

Cashmere fineness is getting thicker, which is one of the key problems in cashmere breeding, however, there have been no systematic studies on the molecular regulation of cashmere fineness. The aim of this study was to investigate the relationship between KRT26 and TCHH gene polymorphism and production performance in Liaoning cashmere goats (LCG). The potential single nucleotide polymorphisms (SNPs) of LCG were detected by sequence alignment and PCR-Seq polymorphism of KRT26 and TCHH genes and analyzed the effect of SNPs on production performance by SPSS software. Two SNPs sites (A559T and A6839G) of two genes were detected. The AA genotype of KRT26 A559T locus was the dominant genotype. AG and GG at TCHH A6839G locus were the dominant genotypes. AAAA was the dominant haplotype combination. The results showed that KRT26 and TCHH genes were associated with cashmere fineness of LCG, and A559T (AA) and A6839G (GG) genotypes were the preferred marker genotypes for cashmere fineness, which provided more theoretical basis for further research on cashmere fineness.

Structural characterization of human peptidyl-arginine deiminase type III by X-ray crystallography

The Ca2+-dependent enzyme peptidyl-arginine deiminase type III (PAD3) catalyses the deimination of arginine residues to form citrulline residues in proteins such as keratin, filaggrin and trichohyalin. This is an important post-translation modification that is required for normal hair and skin formation in follicles and keratocytes. The structure of apo human PAD3 was determined by X-ray crystallography to a resolution of 2.8 Å. The structure of PAD3 revealed a similar overall architecture to other PAD isoforms: the N-terminal and middle domains of PAD3 show sequence and structural variety, whereas the sequence and structure of the C-terminal catalytic domain is highly conserved. Structural analysis indicates that PAD3 is a dimer in solution, as is also the case for the PAD2 and PAD4 isoforms but not the PAD1 isoform.

Protein-coding repeat polymorphisms strongly shape diverse human phenotypes

Many human proteins contain domains that vary in size or copy number because of variable numbers of tandem repeats (VNTRs) in protein-coding exons. However, the relationships of VNTRs to most phenotypes are unknown because of difficulties in measuring such repetitive elements. We developed methods to estimate VNTR lengths from whole-exome sequencing data and impute VNTR alleles into single-nucleotide polymorphism haplotypes. Analyzing 118 protein-altering VNTRs in 415,280 UK Biobank participants for association with 786 phenotypes identified some of the strongest associations of common variants with human phenotypes, including height, hair morphology, and biomarkers of health. Accounting for large-effect VNTRs further enabled fine-mapping of associations to many more protein-coding mutations in the same genes. These results point to cryptic effects of highly polymorphic common structural variants that have eluded molecular analyses to date.

Structures of human peptidylarginine deiminase type III provide insights into substrate recognition and inhibitor design

Peptidylarginine deiminase type III (PAD3) is an isozyme belonging to the PAD enzyme family that converts arginine to citrulline residue(s) within proteins. PAD3 is expressed in most differentiated keratinocytes of the epidermis and hair follicles, while S100A3, trichohyalin, and filaggrin are its principal substrates. In this study, the X-ray crystal structures of PAD3 in six states, including its complex with the PAD inhibitor Cl-amidine, were determined. This structural analysis identified a large space around Gly374 in the PAD3-Ca2+-Cl-amidine complex, which may be used to develop novel PAD3-selective inhibitors. In addition, similarities between PAD3 and PAD4 were found based on the investigation of PAD4 reactivity with S100A3 in vitro. A comparison of the structures of PAD1, PAD2, PAD3, and PAD4 implied that the flexibility of the structures around the active site may lead to different substrate selectivity among these PAD isozymes.

PAD2-mediated citrullination of Fibulin-5 promotes elastogenesis

The formation of elastic fibers is active only in the perinatal period. How elastogenesis is developmentally regulated is not fully understood. Citrullination is a unique form of post-translational modification catalyzed by peptidylarginine deiminases (PADs), including PAD1-4. Its physiological role is largely unknown. By using an unbiased proteomic approach of lung tissues, we discovered that FBLN5 and LTBP4, two key elastogenic proteins, were temporally modified in mouse and human lungs. We further demonstrated that PAD2 citrullinated FBLN5 preferentially in young lungs compared to adult lungs. Genetic ablation of PAD2 resulted in attenuated elastogenesis in vitro and age-dependent emphysema in vivo. Mechanistically, citrullination protected FBLN5 from proteolysis and subsequent inactivation of its elastogenic activity. Furthermore, citrullinated but not native FBLN5 partially rescued in vitro elastogenesis in the absence of PAD activity. Our data uncover a novel function of citrullination, namely promoting elastogenesis, and provide additional insights to how elastogenesis is regulated.

Grainyhead-like transcription factors: guardians of the skin barrier

There has been selective pressure to maintain a skin barrier since terrestrial animals evolved 360 million years ago. These animals acquired an unique integumentary system with a keratinized, stratified, squamous epithelium surface barrier. The barrier protects against dehydration and entry of microbes and toxins. The skin barrier centres on the stratum corneum layer of the epidermis and consists of cornified envelopes cemented by the intercorneocyte lipid matrix. Multiple components of the barrier undergo cross-linking by transglutaminase (TGM) enzymes, while keratins provide additional mechanical strength. Cellular tight junctions also are crucial for barrier integrity. The grainyhead-like (GRHL) transcription factors regulate the formation and maintenance of the integument in diverse species. GRHL3 is essential for formation of the skin barrier during embryonic development, whereas GRHL1 maintains the skin barrier postnatally. This is achieved by transactivation of Tgm1 and Tgm5, respectively. In addition to its barrier function, GRHL3 plays key roles in wound repair and as an epidermal tumour suppressor. In its former role, GRHL3 activates the planar cell polarity signalling pathway to mediate wound healing by providing directional migration cues. In squamous epithelium, GRHL3 regulates the balance between proliferation and differentiation, and its loss induces squamous cell carcinoma (SCC). In the skin, this is mediated through increased expression of MIR21, which reduces the expression levels of GRHL3 and its direct target, PTEN, leading to activation of the PI3K-AKT signalling pathway. These data position the GRHL family as master regulators of epidermal homeostasis across a vast gulf of evolutionary history.

Hair Loss Caused by Gain-of-Function Mutant TRPV3 Is Associated with Premature Differentiation of Follicular Keratinocytes

Gain-of-function mutations in the TRPV3 gene can cause Olmsted syndrome characterized by palmoplantar and periorificial keratoderma, itch, and hair loss. The mechanism underlying the hair loss remains unclear. In this study, we engineered an Olmsted syndrome mouse model by introducing the point mutation G568V to the corresponding Trpv3 locus in the mice. These mice developed fully penetrant hair loss. The hair loss was associated with premature differentiation of follicular keratinocytes characterized by precocious degeneration of trichohyalin and keratins, increased production of deiminated proteins, elevated apoptosis, and attenuation of transcription regulators (Foxn1, Msx2, Dlx3, and Gata3) known to regulate hair follicle differentiation. These abnormalities occurred in the medial‒proximal region of the inner root sheath and the hair shaft, where Trpv3 is highly expressed, and correlated with an impaired formation of the hair canal and the hair shaft. The mutant Trpv3 mice also exhibited increased proliferation in the outer root sheath, accelerated hair cycle, reduction of hair follicle stem cells, and miniaturization of regenerated hair follicles. Findings from this study suggest that precocious maturation of postmitotic follicular keratinocytes drives hair loss in patients with Olmsted syndrome.