Keratin-associated Proteins Research Articles

Complex Changes in the Apoptotic and Cell Differentiation Programs during Initiation of the Hair Follicle Response to Chemotherapy

Chemotherapy has severe side-effects for normal rapidly proliferating organs, such as hair follicle, and causes massive apoptosis in hair matrix keratinocytes followed by hair loss. To define the molecular signature of hair follicle response to chemotherapy, human scalp hair follicles cultured ex vivo were treated with doxorubicin and global microarray analysis was performed 3 hours after treatment. Microarray data revealed changes in expression of 504 genes in doxorubicin-treated hair follicles versus the controls. Among these genes, upregulations of several tumor necrosis factor family of apoptotic receptors (FAS, TRAIL receptors 1/2), as well as of a large number of the keratin-associated protein genes were seen after doxorubicin treatment. Hair follicle apoptosis induced by doxorubicin was significantly inhibited by either TRAIL neutralizing antibody or caspase 8 inhibitor, thus suggesting a novel role for TRAIL receptor signaling in mediating doxorubicin-induced hair loss. These data demonstrate that the early phase of the hair follicle response to doxorubicin includes upregulation of apoptosis-associated markers, as well as substantial re-organization of the terminal differentiation programs in hair follicle keratinocytes. These data provide an important platform for further studies towards the design of novel approaches for management of chemotherapy-induced hair loss.

Effect of Heat Treatment on Human Hair Keratin Film

Human hair keratin film consisting of fine fibrous and particle structures has been utilized as an alternative device to hair samples. Since application of heat is a well-known factor causing hair damage, the thermal effects on the keratin films and hair samples were examined focusing on color change, morphological observation, protein solubility, and oxidative proteins. The opaque white appearance of the keratin film changed to a yellow/light brown color by the thermal treatments at more than 170°C. This color change at 170°C and higher was also detected by spectrophotometry. Scanning electron microscopy (SEM) observation showed that there was little change in the fine structures of the keratin films and hair samples even after a thermal treatment at 200°C for 10 min. When protein solubility of heat-treated keratin films and hair samples were examined using a solution containing dithiothreitol (DTT) and urea, the amounts of proteins solubilized from heat-treated keratin films and hair samples were less than those from untreated keratin film and hair samples. The protein solubility decreased in a heating timeand temperature-dependent manner. A linear relationship between solubilized proteins and a heating temperature of 110 to 160°C was found. Compared to hair samples, the degree of change was clearly evident in the keratin films. The solubilized proteins consisted of keratin and keratin-associated proteins (KAPs). The amount of carbonylated proteins increased in the films treated at 120–180°C. This data suggests that thermal treatment promotes protein oxidization and induce the formation of “Stable Structure” which has not yet been identified. In any event, hair thermal damage will be quantitatively evaluated using the keratin films in place of hair samples.

The sheep KAP8-2 gene, a new KAP8 family member that is absent in humans.

The keratin-associated proteins (KAPs) are fundamental components of hair and wool fibres, and are believed to in part be responsible for some of the properties of these fibres. KAPs can be divided into three groups: the high sulphur (HS) KAPs, the ultra-high sulphur (UHS) KAPs and the high glycine-tyrosine (HGT) KAPs. KAP8 is a HGT-KAP family and was believed to be coded for by a single gene in both humans and sheep. However, the recent identification of a KAP8-2 gene in goats led us to investigate whether a KAP8-2 gene exists in sheep.A BLAST search of the Ovine Genome Assembly v2.0 using the coding sequence of caprine KRTAP8-2 identified a homologous region on sheep chromosome 1 (OAR1:123005473_123005664; E = e-101). This region was clustered with a number of previously identified KAP genes including (in order from the centromere) KRTAP11-1, KRTAP7-1, KRTAP8-1, KRTAP6-2, KRTAP6-1, KRTAP13-3 and KRTAP24-1. PCR-SSCP analysis of the notional gene revealed two dissimilar PCR-SSCP banding patterns, representing two DNA sequences. A single nucleotide difference 21 bp upstream of the TATA box was identified. The two sequences did not have great homology with known ovine KRTAP sequences, but high sequence identity was found with KRTAP8-2 from goats and reindeer. These results suggest that sheep possess a KAP8-2 gene and that this gene is polymorphic.The notional KAP8-2 protein is comprised of 63 amino acid residues and is rich in glycine and tyrosine, but has a low cysteine content. In contrast to other HGT-KAPs, ovine KAP8-2 contains more acidic amino acid residues, and this would likely result in a lower isoelectric point (pI) of 6.3.Electronic supplementary materialThe online version of this article (doi:10.1186/2193-1801-3-528) contains supplementary material, which is available to authorized users.

Mammalian keratin associated proteins (KRTAPs) subgenomes: disentangling hair diversity and adaptation to terrestrial and aquatic environments.

BackgroundAdaptation of mammals to terrestrial life was facilitated by the unique vertebrate trait of body hair, which occurs in a range of morphological patterns. Keratin associated proteins (KRTAPs), the major structural hair shaft proteins, are largely responsible for hair variation.ResultsWe exhaustively characterized the KRTAP gene family in 22 mammalian genomes, confirming the existence of 30 KRTAP subfamilies evolving at different rates with varying degrees of diversification and homogenization. Within the two major classes of KRTAPs, the high cysteine (HS) subfamily experienced strong concerted evolution, high rates of gene conversion/recombination and high GC content. In contrast, high glycine-tyrosine (HGT) KRTAPs showed evidence of positive selection and low rates of gene conversion/recombination. Species with more hair and of higher complexity tended to have more KRATP genes (gene expansion). The sloth, with long and coarse hair, had the most KRTAP genes (175 with 141 being intact). By contrast, the “hairless” dolphin had 35 KRTAPs and the highest pseudogenization rate (74% relative to the 19% mammalian average). Unique hair-related phenotypes, such as scales (armadillo) and spines (hedgehog), were correlated with changes in KRTAPs. Gene expression variation probably also influences hair diversification patterns, for example human have an identical KRTAP repertoire as apes, but much less hair.ConclusionsWe hypothesize that differences in KRTAP gene repertoire and gene expression, together with distinct rates of gene conversion/recombination, pseudogenization and positive selection, are likely responsible for micro and macro-phenotypic hair diversification among mammals in response to adaptations to ecological pressures.Electronic supplementary materialThe online version of this article (doi:10.1186/1471-2164-15-779) contains supplementary material, which is available to authorized users.

Internal structure changes in bleached black human hair resulting from chemical treatments: A Raman spectroscopic investigation

In order to investigate in detail the influence of chemical treatments (reduction, hydrolyzed eggwhite protein (HEWP) treatment, and oxidation) on damaged hair keratin fibers, the structure of cross-sections at various depths of excessively bleached (damaged) black human hair resulting from a permanent waving process was directly analyzed using Raman spectroscopy. It was found that l-cysteine (CYS) largely reacted with the gauche-gauche-gauche (GGG) conformation of disulfide (–SS–) groups (while CYS did not react with the trans-gauche-trans (TGT) conformation). In particular, not only the GGG content, but also the cysteic acid content existing throughout the cortex region of the excessively bleached human hair remarkably decreased by performing the oxidation process after reduction. On the other hand, the GGG content of the excessively bleached black human hair increased, while the TGT content decreased by performing the oxidation process after reduction and then HEWP treatment processes.From these experiments, the authors concluded that some of the keratin associated protein (KAP), which has a rich –SS– content and cysteic acid content was eluted from the cortex region along with the disconnection of –SS– groups, thereby leading to the remarkable reduction in the reconnection of –SS– groups of the excessively bleached black human hair after the permanent waving process (the reduction and oxidation processes). Also, the authors concluded that the HEWP treatment process in the permanent waving process caused the reconstruction of the KAP, thereby contributing to the acceleration of the reconnection of –SS– groups during the oxidation process.

Transcriptional regulation analysis and the potential transcription regulator site in the extended KAP6.1 promoter in sheep.

The high glycine/tyrosine type II keratin protein 6.1 (KAP6.1) is a member of the keratin-associated protein family, which is restricted to cells in hair follicles and is associated with fiber diameter and fiber curvature in Merino sheep. In this study, we obtained a series of progressive 5'-deletion fragments of the KAP6.1 gene promoter from ovine genomic DNA. The KAP6.1 5'-upstream region was fused to luciferase and transfected into sheep fetal fibroblast cells (sFFCs). We demonstrated that the sequence from -1,523 to -1 bp (taking the A of the initiator methionine ATG as the +1 nt position) gave rise to a higher luciferase activity comparing to the published region from -1,042 to -1 bp. Whereas, decreased transcriptional activity of the KAP6.1 promoter was observed when the sequence extended to -3,699 bp. To identify the DNA elements that are important for transcriptional activity, we performed structural analysis and electrophoretic mobility shift assay (EMSA). Structural analysis of the KAP6.1 promoter showed that transcription factors NF-kappa-B, AP-1, and C/EBP-alpha synergistically activate KAP6.1 promoter, while POU2F1 might function as a strong negative regulator. The EMSA showed that NF-kappa-B element bound to the nuclear protein extracted from sFFCs. We conclude that NF-kappa-B binding site is an enhancer element of KAP6.1 promoter in vitro. The results are potentially useful for elucidating the regulator mechanisms of KAP6.1.

Anticancer properties of peptide fragments of hair proteins.

The primary function of hair and fur covering mammalian skin is to provide mechanical and thermal protection for the body. The proteins that constitute hair are extremely resistant to degradation by environmental factors. However, even durable materials can be slowly broken down by mechanical stresses, biodegradation mediated by endogenous enzymes in the skin or host microbes. We hypothesised that the biodegradation products of hair may possess bioprotective properties, which supplement their physical protective properties. Although evolutionary processes have led to a reduction in the amount of hair on the human body, it is possible that the bioprotective properties of hair biodegradation products have persisted. The human skin is exposed to various environmental carcinogenic factors. Therefore, we hypothesised that the potential bioprotective mechanisms of hair degradation products affect melanoma growth. We used pepsin to partially digest hair enzymatically, and this process produced a water-soluble lysate containing a mixture of peptides, including fragments of keratin and keratin-associated proteins. We found out that the mixtures of soluble peptides obtained from human hair inhibited the proliferation of human melanoma cells in vitro. Moreover, the hair-derived peptide mixtures also inhibited the proliferation of B lymphoma cells and urinary bladder cancer cells. Normal human cells varied in their susceptibility to the effects of the lysate; the hair-derived peptide mixtures modulated the proliferation of normal human fibroblasts but did not inhibit the proliferation of human mesenchymal cells derived from umbilical cord stromal cells. These results suggest that hair-derived peptides may represent a new class of anti-proliferative factors derived from basically structural proteins. Identification of active regulatory compounds and recognition of the mechanism of their action might pave the way to elaboration of new anticancer drugs.

Expression analysis of KAP9.2 and Hoxc13 genes during different cashmere growth stages by qRT-PCR method.

Keratin-associated protein 9.2 (KAP9.2) and Homeobox C13 (Hoxc13) genes were chosen to study because of their biological functions involving hair formation. KAP9.2 gene belongs to the ultra high sulfur KAPs, which is important for hair formation and may have association with cashmere. Hoxc13 takes part in the formation of cashmere keratin and maintaining the normal structure of follicle. It has been reported that Hoxc13 gene exists binding site of KP and KAP genes at its promoter regions in mouse. So the expression of KAP9.2 and Hoxc13 genes was detected at anagen stage vs telogen stage by qRT-PCR. The data showed that KAP9.2 and Hoxc13 gene had similar expression trend at different stages, which indicated that there was interaction between them. KAP9.2 and Hoxc13 gene had lower expression level in anagen than that of in telogen of cashmere growth. In anagen, KAP9.2 and Hoxc13 expressed lower in high cashmere yield individuals than that of in low cashmere yield ones. In telogen, the result was reverse. The study would provide the evidence of involvement of KAP9.2 and Hoxc13 in hair periodic growth.

Gene Expressing Difference in Sclerotial Formation of Morchella conica.

The difference of gene expression between sclerotia-producing and non-sclerotia-producing single spore isolates from Morchella conica were preliminary analyzed by mRNA differential display reverse transcription-polymerase chain reaction (RT-PCR) technique and 67 differential gene fragments were obtained. Fifty-eight of their second PCR products were cloned and sequenced. Thirteen special differential gene fragments related to sclerotial formation were validated by semi-quantitative RT-PCR. Some gene fragments had certain homologies with lipoprotein, cyclin-dependent kinase C-3, glycerophosphoryl diester phosphodiesterase, Rho GDP-dissociation inhibitor, gamma-aminobutyrate permease, OmpA family protein, Transcript antisense to ribosomal RNA protein, sodium-calcium exchange protein and keratin-associated proteins 5, 6. In addition, the putative protein of some DNA fragments had higher similarity with hypothetical protein-coding gene in NCBI database, as well as some were only putative gene fragments. All these fragments were speculated to be the functional gene associated with sclerotial formation in morel.

Synchrotron X-ray absorption spectroscopy analysis of arsenic chemical speciation in human nail clippings

Environmental context Chronic ingestion of arsenic leads to its accumulation in keratinous tissues, which can represent a risk factor for developing cancer. We use synchrotron X-ray absorption spectroscopy to investigate chemical bonding of arsenic in the keratins from nail clippings of volunteers from areas in Atlantic Canada with low-to-moderate arsenic contamination of drinking water. The study helps our understanding of arsenic metabolism and its role in cancer development. Abstract Drinking water aquifers in many areas of the world have naturally elevated levels of inorganic arsenic exceeding the World Health Organization limit. Arsenic concentrations in human nail clippings are commonly used as a biomarker of exposure to this toxic element. However, the chemical form of arsenic accumulated in nail tissues is not well determined. We employed synchrotron microprobe and bulk X-ray absorption spectroscopy techniques to analyse the concentration and chemical speciation of arsenic in the finger- and toenail clippings of volunteers living in the vicinity of Sackville, New Brunswick, Canada. This area is known to have low-to-moderately elevated levels of arsenic in ground water. Arsenic species in clippings were represented by three main groups, distinguished by the As-K near-edge X-ray absorption fine structure spectra: (1) AsIII type, which can be fitted as a mixture of As bound to thiols, and also to oxygen or methyl groups, with a small contribution from AsV species, (2) AsV type, best represented by fitting arsenate in aqueous solution and (3) The AsIII+AsV mixture type. The high proportion (%) of sulfur-bound arsenic species most likely corresponds to binding between arsenic (in its trivalent and, to a lesser extent, pentavalent forms) and cysteine residues in the sulfur-rich fraction of keratin and keratin-associated proteins. Further work is needed to explore whether these chemical species could be used as toxicity biomarkers of human exposure to elevated levels of As in drinking water.

Polymorphisms of KAP6, KAP7, and KAP8 genes in four Chinese sheep breeds.

High glycine-tyrosine proteins (HGTPs), also known as keratin-associated proteins (KAPs), play a key role in the major structures and mechanical properties of wool fiber. Sheep HGTPs consist of three multigene families: KAP6, KAP7, and KAP8 genes. Polymorphisms of these three genes have been proposed to have important effects on wool fiber traits. The aim of the present study was to identify polymorphisms of the KAP6, KAP7, and KAP8 genes in four sheep breeds, including Chinese Merino superfine wool sheep, Hu sheep, a Merino x Hu crossed breed, and Romney sheep. Polymerase chain reaction (PCR) product direct sequencing, PCR-single-strand conformation polymorphism, and cloned sequencing methods were used to find genetic variation and identify polymorphisms in these genes. The Mutation Surveyor v3.97 software was used to analyze the sequences. These methods revealed six different sequences of the KAP6 gene, two different sequences of the KAP7 gene, and five different sequences of the KAP8 gene. Accordingly, three (with frequencies>1%) single nucleotide polymorphisms (SNPs) of the KAP6 gene, one SNP of the KAP7 gene, and five SNPs of the KAP8 gene were detected. Interestingly, some of these sequences were present in only certain sheep breeds, thereby suggesting that these special allele sequences could be used as candidate genes of wool characteristics in further studies.

Geographic distribution and adaptive significance of genomic structural variants: an anthropological genetics perspective.

Anthropological geneticists have successfully used single-nucleotide and short tandem repeat variations across human genomes to reconstruct human history. These markers have also been used extensively to identify adaptive and phenotypic variation. The recent advent of high-throughput genomic technologies revealed an overlooked type of genomic variation: structural variants (SVs). In fact, some SVs may contribute to human adaptation in substantial and previously unexplored ways. SVs include deletions, insertions, duplications, inversions, and translocations of genomic segments that vary among individuals from the same species. SVs are much less numerous than single-nucleotide variants but account for at least seven times more variable base pairs than do single-nucleotide variants when two human genomes are compared. Moreover, recent studies have shown that SVs have higher mutation rates than single-nucleotide variants when the affected base pairs are considered, especially in certain parts of the genome. The null hypothesis for the evolution of SVs, as for single-nucleotide variants, is neutrality. Hence, drift is the primary force that shapes the current allelic distribution of most SVs. However, due to their size, a larger proportion of SVs appear to evolve under nonneutral forces (mostly purifying selection) than do single-nucleotide variants. In fact, as exemplified by several groundbreaking studies, SVs contribute to anthropologically relevant phenotypic variation and local adaptation among humans. In this review, we argue that with the advent of affordable genomic technologies, anthropological scrutiny of genomic structural variation emerges as a fertile area of inquiry to better understand human phenotypic variation. To motivate potential studies, we discuss scenarios through which structural variants (SVs) affect phenotypic variation among humans within an anthropological context. We further provide a methodological workflow in which we analyzed 1000 Genomes deletion variants and identified 16 exonic deletions that are specific to the African continent. We analyzed two of these deletion variants affecting the keratin-associated protein (KAP) cluster in a locus-specific manner. Our analysis revealed that these deletions may indeed affect phenotype and likely evolved under geography-specific positive selection. We outline all the major software and data sets for these analyses and provide the basic R and Perl codes we used for this example workflow analysis. Overall, we hope that this review will encourage and facilitate incorporation of genomic structural variation in anthropological research programs.

Krtap11-1, a hair keratin-associated protein, as a possible crucial element for the physical properties of hair shafts

BackgroundThe physical properties of the hair are predominantly determined by the assembly of keratin bundles. The keratin-associated proteins (Krtaps) are thought to be involved in keratin bundle assembly, however, the functional role of the individual member still remains largely unknown. ObjectiveThe aim of this study is to clarify the role of a unique class of Krtaps, Krtap11-1, in the development and physical properties of the hair. MethodsThe expression regulation of Krtap11-1 was analyzed and its binding partners in the hair cortex were determined. Also, the effects of the forcible expression of this protein on the hair follicle development were analyzed in culture. ResultsThe expression pattern of Krtap11-1 was concentrically asymmetric in the faulty hair that develops in Foxn1nu mice. In cultured keratinocytes, the expression of Krtap11-1 transgene product was strictly regulated by the keratinization process and proteasome-dependent protein elimination. While the association with keratin as well as the cohesive self-assembly of Krtap11-1 appeared to be stabilized by disulfide cross-links, the biotinylated Krtap11-1 probe enabled the adherence to certain type I keratins in the hair cortex, including K31, 33 and 34, in the absence of disulfide formation. When embryonic upper lip rudiments were forcibly introduced with Krtap11-1, the hair follicles formed irregularly arranged globular hair keratin-clumps surrounded by multilayered epithelial cells in culture. ConclusionKrtap11-1 may play an important role on keratin-bundle assembly in the hair cortex and this study provides insight into the physical properties of the hair shaft.

An overview of chemical straightening of human hair: technical aspects, potential risks to hair fibre and health and legal issues

Personal image, as it relates to external beauty, has attracted much attention from the cosmetic industry, and capillary aesthetics is a leader in consumption in this area. There is a great diversity of products targeting both the treatment and beautification of hair. Among them, hair straighteners stand out with a high demand by costumers aiming at beauty, social acceptance and ease of daily hair maintenance. However, this kind of treatment affects the chemical structure of keratin and of the hair fibre, bringing up some safety concerns. Moreover, the development of hair is a dynamic and cyclic process, where the duration of growth cycles depends not only on where hair grows, but also on issues such as the individual's age, dietary habits and hormonal factors. Thus, although hair fibres are composed of dead epidermal cells, when they emerge from the scalp, there is a huge variation in natural wave and the response to hair cosmetics. Although it is possible to give the hair a cosmetically favourable appearance through the use of cosmetic products, for good results in any hair treatment, it is essential to understand the mechanisms of the process. Important information, such as the composition and structure of the hair fibres, and the composition of products and techniques available for hair straightening, must be taken into account so that the straightening process can be designed appropriately, avoiding undesirable side effects for hair fibre and for health. This review aims to address the morphology, chemical composition and molecular structure of hair fibres, as well as the products and techniques used for chemical hair relaxing, their potential risk to hair fibre and to health and the legal aspects of their use.

The effects of zeolite molecular sieve based surface treatments on the properties of wool fabrics

Wool is a natural composite fiber, with keratin and keratin-associated proteins as the key molecular components. The outermost surface of wool fibers comprises a hydrophobic lipid layer that can lead to unsatisfactory processing and properties of fabric products. In this study, molecular sieve 5A, a Na+ and Ca2+ exchanged type A zeolite with a 1:1 Si:Al ratio was integrated onto the surface of wool using 3-mercaptopropyl trimethoxy silane. The resultant surface morphology, hydrophilicity and mechanical performance of the treated wool fabrics were then evaluated. Notably, the surface hydrophilicity of wool was observed to increase dramatically. When wool was treated with a dispersion of 2wt% acetic acid, 2.5wt% zeolite and 0.3wt% or more silane, the water contact angle was observed to decrease from an average value of 148° to 0° over a period of approximately 30s. Scanning electron microscopic imaging indicated good coverage of the wool surface with zeolite particles, with infrared spectroscopic evaluation indicating strong bonding of the dealuminated zeolite to wool keratins. This application of zeolite showed no adverse effects on the tensile and other mechanical properties of the fabric. This study indicates that zeolite-based treatment is a potentially efficient approach to increasing the surface hydrophilicity and modifying other key surface properties of wool and wool fabrics.

Radiographic findings regarding the toe crena

Radiographic findings regarding the toe crena

Molecular characterization of caprine KRTAP13-3 in Liaoning cashmere goat in China

Keratin-associated proteins are a main structural component of hair and wool fibers and may have effects on their characteristics. There are four KAP13 gene members that have been reported in humans, and the KAP13-3 gene has been identified in sheep and cattle, but it has not yet been identified in goats. This led us to search for the caprine KAP13-3 gene. In this study, the caprine KAP13-3 gene was polymerase chain reaction (PCR) amplified, and PCR single-stranded conformational polymorphism (PCR-SSCP) analysis was used to detect genetic variation in 214 Liaoning cashmere goats from China. PCR amplicons of 559 bp were obtained. Sequencing of the amplicons confirmed eight different sequences, and they were named alleles A–H. All of these sequences showed a high sequence homology to known KRTAP13-3 sequences from sheep and cattle. Nine nucleotide substitutions were identified within the KRTAP13-3 coding region, and all of these were nonsynonymous. All sequences showed an open reading frame of 471 nucleotides encoding 156 amino acids. This polypeptide contained high levels of serine (23.08–23.72 mol%), cysteine (10.26–11.54 mol%), and threonine (5.66 mol%). The polypeptide had high calculated pI values (9.02–9.59). The variation reported in the caprine KAP13-3 gene might affect gene expression, primary protein structure, and the character of the resultant cashmere fibers.

Frizzled6 Deficiency Disrupts the Differentiation Process of Nail Development

Nails protect the soft tissue of the tips of digits. The molecular mechanism of nail (and claw) development is largely unknown, but we have recently identified a Wnt receptor gene, Frizzled6 (Fzd6) that is mutated in a human autosomal-recessive nail dysplasia. To investigate the action of Fzd6 in claw development at the molecular level, we compared gene expression profiles of digit tips of wild-type and Fzd6−/− mice, and show that Fzd6 regulates the transcription of a striking number of epidermal differentiation-related genes. Sixty-three genes encoding keratins, keratin associated proteins, and transglutaminases and their substrates were significantly down-regulated in the knockout mice. Among them, four hard keratins, Krt86, Krt81, Krt34 and Krt31; two epithelial keratins, Krt6a and Krt6b; and transglutaminase1 were already known to be involved in nail abnormalities when dysregulated. Immunohistochemical studies revealed decreased expression of Krt86, Krt6b and involucrin in the epidermal portion of the claw field in the knockout embryos. We further showed that Dkk4, a Wnt antagonist, was significantly down-regulated in Fzd6−/− mice along with Wnt, Bmp and Hh family genes; and Dkk4 transgenic mice showed a subtly but appreciably modified claw phenotype. Thus, Fzd6-mediated Wnt signaling likely regulates the overall differentiation process of nail/claw formation.

Investigating the origins of nanostructural variations in differential ethnic hair types using X‐ray scattering techniques

Human hair is a major determinant of visual ethnic differentiation. Although hair types are celebrated as part of our ethnic diversity, the approach to hair care has made the assumption that hair types are structurally and chemically similar. Although this is clearly not the case at the macroscopic level, the intervention of many hair treatments is at the nanoscopic and molecular levels. The purpose of the work presented here is to identify the main nanoscopic and molecular hierarchical differences across five different ethnic hair types from hair fibres taken exclusively from the scalp. These are Afro (subdivided into elastic 'rubber' and softer non-elastic 'soft'), Chinese, European and Mullato (mixed race). Small angle X-Ray scattering (SAXS) is a technique capable of resolving nanostructural variations in complex materials. Individual hair fibres from different ethnic hair types were used to investigate structural features found in common and also specific to each type. Simultaneous wide angle X-Ray scattering (WAXS) was used to analyse the submolecular level structure of the fibrous keratin present. The data sets from both techniques were analysed with principal component analysis (PCA) to identify underlying variables. Principal component analysis of both SAXS and WAXS data was shown to discriminate the scattering signal between different hair types. The X-ray scattering results show a common underlying keratin intermediate filament (KIF) structure. However, distinct differences were observed in the preferential orientation and intensity signal from the lipid component of the hair. In addition, differences were observed in the intensity distribution of the very low-angle sample-dependent diffuse scatter surrounding the 'beamstop.' The results indicate that the fibrous keratin scaffold remains consistent between ethnic hair types. The hierarchies made by these may be modulated by variation in the content of keratin-associated proteins (KAPs) and lipids that alter the interfacial structures and lead to macroscopic differences in hair morphology.

Bidirectional binding property of high glycine–tyrosine keratin-associated protein contributes to the mechanical strength and shape of hair

Since their first finding in wool 50years ago, keratin-associated proteins (KAPs), which are classified into three groups; high sulfur (HS) KAPs, ultra high sulfur (UHS) KAPs, and high glycine-tyrosine (HGT) KAPs, have been the target of curiosity for scientists due to their characteristic amino acid sequences. While HS and UHS KAPs are known to function in disulfide bond crosslinking, the function of HGT KAPs remains unknown. To clarify the function as well as the binding partners of HGT KAPs, we prepared KAP8.1 and other KAP family proteins, the trichocyte intermediate filament proteins (IFP) K85 and K35, the head domain of K85, and the C subdomain of desmoplakin C-terminus (DPCT-C) and investigated the interactions between them in vitro. Western blot analysis and isothermal titration calorimetry (ITC) indicate that KAP8.1 binds to the head domain of K85, which is helically aligned around the axis of the intermediate filament (IF). From these results and transmission electron microscopy (TEM) observations of bundled filament complex in vitro, we propose that the helical arrangement of IFs found in the orthocortex, which is uniquely distributed on the convex fiber side of the hair, is regulated by KAP8.1. Structure-dependent binding of DPCT-C to trichocyte IFP was confirmed by Western blotting, ITC, and circular dichroism. Moreover, DPCT-C also binds to some HGT KAPs. It is probable that such bidirectional binding property of HGT KAPs contribute to the mechanical robustness of hair.