Keratins: the hair shaft's backbone revealed

Transcriptome Analysis Reveals Genes Contributed to Min Pig Villi Hair Follicle in Different Seasons

The Min pig, a local pig breed in China, has a special trait which has intermittent villus and coat hair regeneration. However, the regulation and mechanism of villus in Min pigs have not yet been described. We observed and described the phenotype of Min pig dermal villi in detail and sequenced the mRNA transcriptome of Min pig hair follicles. A total of 1520 differentially expressed genes (DEG) were obtained.K-means hierarchical clustering showed that there was a significant expression pattern difference in winter compared with summer. Gene enrichment and network analysis results showed that the hair growth in Min pigs was closely related to the composition of desmosomes and regulated by an interaction network composed of eight core genes, namely DSP, DSC3, DSG4, PKP1, TGM1, KRT4, KRT15, and KRT84. Methylation analysis of promoters of target genes showed that the PKP1 gene was demethylated. Our study will help to supplement current knowledge of the growth mechanism of different types of hair.

Fabrication and characterization of eco-friendly composite materials from natural animal fibers

A large amount of useless portion, which is discharging from leather industries, pollutes the environment immensely. The discarded part needs to be recycled to yield other valuable products to subside environmental pollution. In this research, we utilized a rejected part (cow hair) of leather industries and unsaturated polyester resin (UPR) to fabricate valued composites to confine atmospheric pollution. A hand-lay-up technique, which is an easy and economical approach, was employed for composites fabrication. A number of cow hair fiber percentages (2, 5, 7, 10, 12, 15, and 20% by weight) were taken into consideration to investigate the impact of fiber loading on composites. Prepared composites were characterized by a few mechanical properties such as tensile strength (TS), tensile modulus (TM), elongation at break (EB), bending strength (BS), and bending modulus (BM). Fourier Transform Infrared (FTIR), Electron Scanning Microscopy (SEM), and water absorption were also performed to support the data in favor of mechanical properties. Optimum mechanical properties which were supported by the other analysis were achieved for 5% cow hair containing composites.

Translational Neuroendocrinology of Human Skin: Concepts and Perspectives

Human skin responds to numerous neurohormones, neuropeptides, and neurotransmitters that reach it via the vasculature or skin nerves, and/or are generated intracutaneously, thus acting in a para- and autocrine manner. This review focuses on how neurohormones impact on human skin physiology and pathology. We highlight basic concepts, major open questions, and translational research perspectives in cutaneous neuroendocrinology and argue that greater emphasis on neuroendocrine human skin research will foster the development of novel dermatological therapies. Furthermore, human skin and its appendages can be used as highly accessible and clinically relevant model systems for probing nonclassical, ancestral neurohormone functions. This calls for close interdisciplinary collaboration between dermatologists, skin biologists, neuroendocrinologists, and neuropharmacologists.

Hair Growth Promoting Effect of 4HGF Encapsulated with PGA Nanoparticles (PGA-4HGF) by β-Catenin Activation and Its Related Cell Cycle Molecules

Poly-γ-glutamic acid (γ-PGA)-based nanoparticles draw remarkable attention as drug delivery agents due to their controlled release characteristics, low toxicity, and biocompatibility. 4HGF is an herbal mixture of Phellinus linteus grown on germinated brown rice, Cordyceps militaris grown on germinated soybeans, Polygonum multiflorum, Ficus carica, and Cocos nucifera oil. Here, we encapsulated 4HGF within PGA-based hydrogel nanoparticles, prepared by simple ionic gelation with chitosan, to facilitate its penetration into hair follicles (HFs). In this study, we report the hair promoting activity of 4HGF encapsulated with PGA nanoparticles (PGA-4HGF) and their mechanism, compared to 4HGF alone. The average size of spherical nanoparticles was ~400 nm in diameter. Continuous release of PGA-4HGF was observed in a simulated physiological condition. As expected, PGA-4HGF treatment increased hair length, induced earlier anagen initiation, and elongated the duration of the anagen phase in C57BL/6N mice, compared with free 4HGF treatment. PGA-4HGF significantly increased dermal papilla cell proliferation and induced cell cycle progression. PGA-4HGF also significantly increased the total amount of β-catenin protein expression, a stimulator of the anagen phase, through induction of cyclinD1 and CDK4 protein levels, compared to free 4HGF treatment. Our findings underscore the potential of PGA nanocapsules to efficiently deliver 4HGF into HFs, hence promoting hair-growth. Therefore, PGA-4HGF nanoparticles may be promising therapeutic agents for hair growth disorders.

The biology and genetics of curly hair

Hair fibres show wide diversity across and within all human populations, suggesting that hair fibre form and colour have been subject to much adaptive pressure over thousands of years. All human hair fibres typically have the same basic structure. However, the three-dimensional shape of the entire fibre varies considerably depending on ethnicity and geography, with examples from very straight hair with no rotational turn about the long axis, to the tightly sprung coils of African races. The creation of the highly complex biomaterials in hair follicle and how these confer mechanical functions on the fibre so formed is a topic that remains relatively unexplained thus far. We review the current understanding on how hair fibres are formed into a nonlinear coiled form and which genetic and biological factors are thought to be responsible for hair shape. We report on a new GWAS comparing low and high curl individuals in South Africa, revealing strong links to polymorphic variation in trichohyalin, a copper transporter protein CUTC and the inner root sheath component keratin 74. This builds onto the growing knowledge base describing the control of curly hair formation.

Characterisation of cell cycle arrest and terminal differentiation in a maximally proliferative human epithelial tissue: Lessons from the human hair follicle matrix

Human hair follicle (HF) growth and hair shaft formation require terminal differentiation-associated cell cycle arrest of highly proliferative matrix keratinocytes. However, the regulation of this complex event remains unknown. CIP/KIP family member proteins (p21^CIP1, p27^KIP1 and p57^KIP2) regulate cell cycle progression/arrest, endoreplication, differentiation and apoptosis. Since they have not yet been adequately characterized in the human HF, we asked whether and where CIP/KIP proteins localise in the human hair matrix and pre-cortex in relation to cell cycle activity and HF-specific epithelial cell differentiation that is marked by keratin 85 (K85) protein expression. K85 expression coincided with loss or reduction in cell cycle activity markers, including in situ DNA synthesis (EdU incorporation), Ki-67, phospho-histone H3 and cyclins A and B1, affirming a post-mitotic state of pre-cortical HF keratinocytes. Expression of CIP/KIP proteins was found abundantly within the proliferative hair matrix, concomitant with a role in cell cycle checkpoint control. p21^CIP1, p27^KIP1 and cyclin E persisted within post-mitotic keratinocytes of the pre-cortex, whereas p57^KIP2 protein decreased but became nuclear. These data imply a supportive role for CIP/KIP proteins in maintaining proliferative arrest, differentiation and anti-apoptotic pathways, promoting continuous hair bulb growth and hair shaft formation in anagen VI. Moreover, post-mitotic hair matrix regions contained cells with enlarged nuclei, and DNA in situ hybridisation showed cells that were >2N in the pre-cortex. This suggests that CIP/KIP proteins might counterbalance cyclin E to control further rounds of DNA replication in a cell population that has a propensity to become tetraploid. These data shed new light on the in situ-biography of human hair matrix keratinocytes on their path of active cell cycling, arrest and terminal differentiation, and showcase the human HF as an excellent, clinically relevant model system for cell cycle physiology research of human epithelial cells within their natural tissue habitat.

Genetics of syndromic and non-syndromic hereditary nail disorders

The nail is a unique epithelial skin appendage made up of a fully keratinized nail plate. The nail can be affected in several systemic illnesses, dermatological diseases, and inherited nail disorders. Nail dystrophies can present as isolated disorders or as a part of syndromes. Substantial progress has been achieved in the management and diagnosis of nail diseases; however, not much is known about the underlying molecular controls of nail growth. The homeostasis and development of the nail appendage depend on the intricate interactions between the epidermis and underlying mesenchyme, and comprise different signaling pathways such as the WNT signaling pathway. Digit-tip regeneration in mice and humans has been a known fact for the past six decades; however, only recently the underlying biological mechanisms by which the nail organ achieves digit regeneration have been elucidated. Moreover, significant progress has been made in identifying nail stem cells and localizing stem cell niches in the nail unit. More fascinating, however, is the role they play in orchestrating the processes that lead to the regeneration of the digit. Further elucidating the role of nail stem cells and the signaling pathways driving epithelial-mesenchymal interactions in the nail unit might contribute to the development of novel therapeutic tools for amputees.