Profiling mRNA of the Graying Human Hair Follicle Constitutes a Promising State-of-the-Art Tool to Assess Its Aging: An Exemplary Report

Abstract

Determining hitherto uninvestigated and safe targets to halt the aging process is important in our aging society. Graying is a hallmark of the aging process and may be used to identify aging tissue for comparative analysis. Here we analyzed differential gene expressions between pigmented, gray, and white human scalp skin hair follicles (HFs) from identical donors. Forming intersections between five donors identified 194/192 downregulated and 186/177 upregulated genes in gray/white HFs. These included melanogenesis (tyrosinase; tyrosinase-related protein 1)- and melanosome structure (Melan-A; Pmel17)-associated genes and regulation of melanocyte relevant tyrosine kinases. Alongside these expected changes, regulated genes included nonmelanocyte-related genes associated with aging as well as nonaging-related genes associated with melanocytes. Intriguingly, among them, genes associated with energy metabolism (i.e., glutaminase) and axon guidance (plexin C1) were altered. These results were reflected by pathway analysis and exemplarily confirmed by PCR and immunohistochemical studies. Supplementing cultured HFs with glutamine or plexin C1 revealed biological relevance and pharmacointerventional potential of these microarray results in altering the HF aging process. Together, we present intriguing data obtained from intra-individual sample comparison that suggest the graying HF to be a valid aging model and a promising target for testing therapeutic interventions.

Hair and stress: A pilot study of hair and cytokine balance alteration in healthy young women under major exam stress

“…Decreased hair tip pigmentation detected in exam students at T2 therefore appears to be a promising surrogate indicator of hampered hair growth in a stressed healthy human. In addition, it may indicate oxidative stress [72] and the onset of premature graying [96]. Some changes in hair measures were however also observed in the comparison group between T1, T2 and T3 and no T2 group differences were found.…”

“…To monitor cessation of pigment production at the onset of HF regression, pigmentation was therefore studied in addition to hair cycle staging, as described previously. Analysis was done by histomorphometric assessment, recording fully pigmented HF as such and HF with diluted pigmentation as depigmented ( Fig 4 ) [72]. …”

Age-Related Hair Pigment Loss

“…Recent studies have reported increased melanocyte death by apoptosis and oxidative stress in the human follicular melanin unit of graying HFs [38,39]. In one study, the 'common' deletion in mitochondrial DNA (a marker of oxidative stress) was reported to occur more prominently in graying HFs than in matched normally pigmented HFs when stressed with a pro-oxidant [38].…”

Hair Coloration by Gene Regulation: Fact or Fiction?

“…Microarray analysis is a powerful technique that allows a global perspective on what is occurring in a cell, tissue, or organism at a particular moment through the comparison of the levels of all mRNAs corresponding to the genes being expressed: the transcriptome. Such analysis was conducted by a research group on pigmented and white human HFs [12]. associated with natural human hair colour variation are rather few [4].…”