Proteomic Analysis of Human Nail Plate

Abstract

Shotgun proteomic analysis of the human nail plate identified 144 proteins in samples from Causcasian volunteers. The 30 identified proteins solubilized by detergent and reducing agent, 90% of the total nail plate mass, were primarily keratins and keratin associated proteins. Keratins comprised a majority of the detergent-insoluble fraction as well, but numerous cytoplasmic, membrane and junctional proteins and histones were also identified, indicating broad use by transglutaminases of available proteins as substrates for cross-linking. Two novel membrane proteins were identified, also found in the hair shaft, for which mRNAs were detected only at very low levels by real time polymerase chain reaction in other tissues. Parallel analyses of nail samples from volunteers from Inner Mongolia, China gave essentially the same protein profiles.Comparison of the profiles of nail plate and hair shaft from the latter volunteers revealed extensive overlap of protein constituents. Analyses of samples from an arsenic-exposed population revealed few proteins whose levels were altered substantially but raised the possibility of detecting sensitive individuals in this way.

Protein extraction from human anagen head hairs 1-millimeter or less in total length

“…Of particular note, Rice etal . [11], did not detect KRT38 in hair shaft or nail samples; similar results were observed in this study using a relatively small sample set. KRT38 was not detected in shaft segments, but was present in root segments (Table 2).…”

“…In this study, 11 keratins known to be highly expressed in hairs that were observed at high frequency (i.e.,detected in more than 70 of the samples analyzed) were: KRT32, KRT33A, KRT33B, KRT34, KRT35, KRT39, KRT72, KRT82, KRT83, KRT85, and KRT86. The high-frequency hair keratins identified are in agreement with major hair proteins identified in previous research [34,11,17]. Of particular note, Rice etal .…”

“…Additionally, protein extraction methods used in the studies referenced [35,8,9] employed protein extraction techniques such as bead beating and grinding by mortar and pestle, which result in sample loss, are more susceptible to contamination and are not suitable for small samples. Furthermore, the techniques described in certain studies require multiple extractions to obtain adequate levels of protein for analysis [10,11]. Finally, other methods published use on column sample clean-up which may result in sample loss and significant increase in instrument runtime.…”

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

“…The analysis revealed a rich complexity of nail matrix proteins, but it has found only a few proteins whose levels were substantially altered in the arsenic-exposed population. [27] Considerable variability in total As content was found in finger-and toenails of healthy unexposed volunteers between three ethnic groups (Somali Africans, Asians and Caucasians) living in similar environmental conditions in the United Kingdom. The total concentrations of As in fingernail samples of a Somali African population were significantly higher than in samples from the two other groups.…”

“…[25] In the studies by Goodwin et al [20] and Karagas et al [21] and related studies, [26] arsenic content in toenails and fingernails was tested as a biomarker of arsenic exposure. Nails and hair contain cysteine-rich proteins -a-keratins, [27] which have the propensity to bind arsenic. Both hair and nails have been used in environmental monitoring of human exposure to arsenic and other toxic elements.…”