Proteomic Analysis of Single Hairs

Abstract

Hair is a ubiquitous and robust mammalian tissue with biological, clinical, forensic, social, and economic significance. The hair shaft proteome reflects both structural proteins, dominated by cuticular intermediate filament keratins and associated proteins, and proteins involved in the final cellular processes of terminally differentiating corneocytes prior to cornification. These distinct biological processes involve cell maintenance, biosynthesis, senescence, and xenobiotic response. Because growth occurs rapidly and predictably, there is also temporal organization. The hair shaft proteome also contains genetic and phylogenetic information in the amino acid sequence. Chemically the shaft is highly robust, the result of a highly structured protein matrix with abundant isopeptide and disulfide intermolecular bonds. Sample processing is therefore a challenge that requires robust chemistries but also minimizes the introduction of additional chemical modifications. This protocol depends on the combination of sodium dodecanoate and high levels of reductant to denature the matrix. The result is a proteome that is both readily accessible and can provide biological information to geneticists, developmental biologists, toxicologists, human and wildlife forensic scientists, scientists in the cosmetics industry, and wildlife ecologists.

Keywords: Cornification; Cuticular corneocytes; Forensic proteomics; Hair; Hair shaft protein; Shotgun mass spectrometry; Species identification; Tissue proteomics.