The human hair is an important biological structure whose proteome poses considerable research interest. Hair follicles embedded within the skin constantly interact with growth factors, hormones, and other signaling molecules. Meanwhile, the lesser studied hair shaft is directly exposed to the environment and is a host to the human microbiome. In a recent study, a team led by researchers from Singapore’s Nanyang University provides a new proteomic analysis of the human hair.
Previous work have identified about 300 proteins that comprise the hair structure, mostly dominated by keratins and keratin-associated proteins (KAPs). However, since keratins are very sturdy and difficult to solubilize, they pose a technical hurdle for accurate investigation.
To overcome this, the team used a variety of protein extraction conditions, including the presence of the denaturant and detergent, urea and SDS, respectively. This was followed up by liquid chromatography-tandem mass spectrometry (LC-MS/MS) in a shotgun proteomic approach for protein identification.
As detailed in the their paper in Scientific Reports, the team was able to identify a combined total of 490 proteins. “We found an enrichment of keratin, KAPs, and intermediate filament proteins, which were part of protein networks associated with response to stress, innate immunity, epidermis development, and the hair cycle,” the team notes.
Deamidation, a type of degenerative protein modification linked to aging and longevity, was observed on a sizeable portion of keratins and KAPs. Histones proteins were also identified. In addition to their roles in regulating transcription, histones have also been associated with broad-spectrum microbial activity. The paper concluded that “analysis of the hair proteome, particularly its composition, protein abundances, deamidated hair proteins, and modification sites, may offer a novel approach to explore potential biomarkers of hair health quality, hair diseases, and aging."
Image: Scanning electron microscope (SEM) images of hair shaft showing surface morphology before and after protein extraction techniques. Image courtesy of Siu Kwan Sze, Artur Schmidtchen, and Springer Nature.