Hair greying is associated with active hair growth

Authors


  • Funding sources
    This research was supported by Basic Science Research Program through the National Research Foundation of Korea (NRF), funded by the Ministry of Education, Science and Technology (2009-0086846).

  • Conflicts of interest
    None declared.

Young Ho Lee.
E-mail: yhlee@cnu.ac.kr

Summary

Background  Hair greying is an obvious sign of ageing in humans. White (nonpigmented) hair is thicker than black (pigmented) hair. The growth rate of white hair is also significantly higher than that of black hair. However, the mechanism underlying this is largely unknown.

Objectives  To examine the association between hair greying and hair growth patterns by evaluating expression of the genes or proteins related to hair growth in white and black hairs.

Methods  Morphological characteristics were observed in eyebrow and scalp hairs. The differential expression of genes was analysed in black and white hairs from human scalp by a microarray analysis. Reverse transcription–polymerase chain reaction (RT-PCR) and immunohistochemistry for genes and proteins related to hair growth were performed in black and white hairs.

Results  Keratin and keratin-associated protein (KRTAP) genes in white hair were upregulated at least two-fold in comparison with black hair in a microarray analysis. Upregulation of selected keratin genes and KRTAP4 isoform genes in white hair was validated by RT-PCR. Immunoreactivity for KRT6, KRT14/16 and KRT25 was increased in the hair follicle of white hair compared with black hair. Gene expression of fibroblast growth factor 5 (FGF5) was downregulated in white hair compared with black hair. However, gene expression of FGF7 was upregulated in white hair compared with black hair.

Conclusions  Expression of genes and proteins associated with active hair growth is upregulated in white (nonpigmented) hair compared with black (pigmented) hair. These results suggest that hair greying is associated with active hair growth.

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