Differences between ultrastructure and protein composition in straight hair fibres

Age-associated thin hair displays molecular, structural and mechanical characteristic changes

Hair thinning occurs during normal chronological aging in women and in men leading to an increased level of thinner hair shafts alongside original thicker shafts. However, the characteristics of age-associated thin hairs remain largely unknown. Here we analyzed these characteristics by comparing at multiscale thin and thick hairs originated from Caucasian women older than 50 years. We observed that the cortex of thick hair contains many K35(+)/K38(-) keratinocytes that decrease in number with decreasing hair diameter. Accordingly, X-ray diffraction revealed differences supporting that thin and thick hairs are different with regards to the nature of the intermediate filaments making up their cortices. In addition, we observed a direct correlation between hair ellipticity and diameter with thin hairs having an unexpected round shape compared to the elliptic shape of thick hairs. We also observed fewer cuticle layers and a reduced frequency of a medullae in thin hairs. Regarding mechanical properties, thin hairs exhibited a surprising increased rigidity, a decrease of the viscosity and a decrease of the water diffusion coefficient. Hence, aged-associated thin hairs exhibit numerous modifications likely due to changes of hair differentiation program as evidenced by the modulations in the expression of hair keratins and keratin-associated proteins and by the X-ray diffraction specters. Hence, hair thinning with age does not consist simply of the production of a smaller hair. It is rather a more profound process likely relying on the implementation of an "aged hair program" that takes place within the hair follicle.

Domestic animal proteomics in the 21st century: A global retrospective and viewpoint analysis

Animal production and health are of significant economic importance, particularly regarding the world food supply. Animal and veterinary sciences have evolved immensely in the past six decades, particularly in genetics, nutrition, housing, management and health. To address major challenges such as those posed by climate change or metabolic disorders, it is of utmost importance to use state-of-the-art research tools. Proteomics and the other post-genomic tools (transcriptomics or metabolomics) are among them. Proteomics has experienced a considerable development over the last decades. This brought developments to different scientific fields. The use and adoption of proteomics tools in animal and veterinary sciences has some limitations (database availability or access to proteomics platforms and funding). As a result, proteomics' use by animal science researchers varies across the globe. In this viewpoint article, we focus on the developments of domestic animal proteomics over the last decade in different regions of the globe and how the researchers have coped with such challenges. In the second part of the article, we provide examples of funding, educational and laboratory establishment initiatives designed to foster the development of (animal-based) proteomics. International scientific collaboration is a definitive and key feature in the development and advancement of domestic animal proteomics. SIGNIFICANCE: Animal production and health are very important for food supply worldwide particularly as a source of proteinaceous foods. Animal and veterinary sciences have evolved immensely in the last decades. In order to address the major contemporary challenges facing animal and veterinary sciences, it is of utmost importance to use state-of-the-art research tools such as Proteomics and other Omics. Herein, we focus on the major developments in domestic animal proteomics worldwide during the last decade and how different regions of the world have used the technology in this specific research field. We address also major international efforts aiming to increase the research output in this area and highlight the importance of international cooperation to address specific problems inherent to domestic animal proteomics.

Expression Profiling and Functional Characterization of miR-26a and miR-130a in Regulating Zhongwei Goat Hair Development via the TGF-β/SMAD Pathway

The Zhongwei goat is an important and unique goat breed indigenous to China. It has a natural hair curling phenotype at birth, but the degree of curling gradually decreases with growth. The molecular mechanism underlying the dynamic changes in the wool curvature in Zhongwei goats is poorly understood. MicroRNAs (miRNAs) play important roles in many biological processes, including hair growth and development. In this study, we selected skins from Zhongwei goats at different ages (45 and 108 days) that exhibited different levels of hair curvature and performed miRNA sequencing to explore the molecular mechanism of hair bending. In total, 28 significantly differentially expressed miRNAs (DE miRNAs) were identified in the three groups of samples between the two developmental stages. An analysis of the target genes of the above-mentioned DE miRNAs by the Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analyses indicated that the DE miRNAs were involved in signal pathways which were previously associated with hair bending and hair follicle development, such as the TGF-β/SMAD, PI3K-Akt, JAK-STAT, and MAPK pathways. A comprehensive analysis of the correlations between the miRNA-seq results and issued transcriptional findings indicated that SMAD1 was a target gene of miR-26a and SMAD5 was a target gene of miR-130a. Furthermore, goat dermal papilla cells were successfully isolated and purified to determine the role of miRNAs in follicle development in vitro. The study results demonstrated that miR-130a and miR-26a had significant effects on the proliferation of dermal papilla cells. In addition, the detection results of mRNA and protein levels indicate that the overexpression of miR-26a can promote the expression of related genes in the TGF-β/SMAD pathway, while miR-130a has the opposite substitution effect. The dual luciferase report test showed that miR-26a targeted the SMAD1 gene and reduced the expression of the SMAD1 protein in hair papillary cells. Our results identified DE microRNAs which perhaps change at the time of hair straightening in Zhongwei goats and explore the role of miR-26a and miR-130a in dermal papilla cells proliferation. The present study provided a theoretical basis to explore the mechanisms underlying the Zhongwei hair growth and curly phenotype.

Improved two-dimensional electrophoretic mapping of Japanese human hair proteins; application to curved and straight Japanese human hairs; and protein identification by MALDI MS and MS/MS quadrupole time-of-flight mass spectrometry

OBJECTIVES

To evaluate improved protein extraction and two-dimensional electrophoresis (2DE) separation methods with Japanese reference human hair (JRH); to determine whether fibre curvature is related to protein composition in curly and straight Japanese women's human hair (JHH) samples; and to identify proteins from JRH 2DE maps and expression differences between curly and straight JHH.

METHODS

Hair keratin and keratin-associated proteins (KAPs) were extracted intact with dithiothreitol or tris(2-carboxyethyl) phosphine from JRH or from curved or straight JHH. Extracted proteins were isoelectric-focused on first-dimensional pH gradient gel strips, then separated by molecular weight on laboratory-made, second-dimension, large format gels. The software compared protein abundance between duplicate 2DE gels of curved and straight JHH. Thirty-eight proteins from a JRH 2DE gel were enzyme-cleaved for MALDI-TOF-MS analysis to determine peptide composition, and where possible, de novo sequencing gave peptide sequence data. An in-house human hair protein database incorporating ninety-eight annotated protein sequences assisted MS analysis.

RESULTS

2DE gels of tris(2-carboxyethyl) phosphine-extracted JRH improved keratin and KAP resolution and number compared to those of dithiothreitol-extracted JRH and published commercially made second-dimensional gels. Silver-stained 2DE gels of the straight or curved JHH sets were remarkably similar. Over-staining to reveal basic proteins caused poor resolution of the major acidic protein classes. Software comparisons of fifty-nine resolved proteins revealed two were significantly different in abundance between curved and straight hairs but in insufficient amounts for MS analysis. MS identified twelve proteins from a JRH CBBG-stained 2DE gel: six type II keratins, three type I keratins and three high sulphur proteins. A further eight were potential conformational isoforms and isoelectric variants of the identified proteins bringing the total to twenty identified or partially identified proteins.

CONCLUSION

Root-end human hair extraction with tris(2-carboxyethyl) phosphine improves protein resolution and visualizes more proteins on large format 2DE gels. The two minor protein differences between duplicate straight or curved JHH 2DE gels were unlikely to change fibre structure from straight to curved hair. MS results confirmed that multiple isoforms exist of various hair proteins. Low sequence coverage prevented distinction between members in rows of homologous protein spots of similar molecular weight.

Helical twist direction in the macrofibrils of keratin fibres is left handed

Macrofibrils, the main structural features within the cortical cells of mammalian hair shafts, are long composite bundles of keratin intermediate filaments (KIFs) embedded in a matrix of keratin-associated proteins. The KIFs can be helically arranged around the macrofibril central axis, making a cylinder within which KIF helical angle relative to macrofibril axis increases approximately linearly from macrofibril centre to edge. Mesophase-based self-assembly has been implicated in the early formation of macrofibrils, which first appear as liquid-crystal tactoids in the bulb of hair follicles. Formation appears to be driven initially by interactions between pre-keratinized KIFs. Differences in the nature of these KIF-KIF interactions could result in all macrofibrils being internally twisted in a single handedness, or a 50:50 mixture of handedness within each cortical cell. We data-mined 41 electron tomograms containing three-dimensional macrofibril data from previously published studies of hair and wool. In all 644 macrofibrils examined we found that within each tomogram all macrofibrils had the same handedness. We concluded that earlier reports of left- and right-handed macrofibrils were due to artefacts of imaging or data processing. A handedness marker was used to confirm (using re-imaged sections from earlier studies) that, in both human and sheep, all macrofibrils are left-handed around the macrofibril axis. We conclude that this state is universal within mammalian hair. This also supports the conclusion that the origin of macrofibril twist is the expression of chiral twisting forces between adjacent KIFs, rather than mesophase splay and bending forces relaxing to twisting forces acting within a confined space.