title: Hair greying is associated with active hair growth.
abstract: 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.
  
  
  OBJECTIVE
  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.
authors.affiliation: Department of Anatomy, Chungnam National University, 55, Munhwa-ro, Daejeon 301-747, Korea.
authors.forename: H I
authors.initials: HI
authors.lastname: Choi
authors.forename: G I
authors.initials: GI
authors.lastname: Choi
authors.forename: E K
authors.initials: EK
authors.lastname: Kim
authors.forename: Y J
authors.initials: YJ
authors.lastname: Choi
authors.forename: K C
authors.initials: KC
authors.lastname: Sohn
authors.forename: Y
authors.initials: Y
authors.lastname: Lee
authors.forename: C D
authors.initials: CD
authors.lastname: Kim
authors.forename: T J
authors.initials: TJ
authors.lastname: Yoon
authors.forename: H J
authors.initials: HJ
authors.lastname: Sohn
authors.forename: S H
authors.initials: SH
authors.lastname: Han
authors.forename: S
authors.initials: S
authors.lastname: Kim
authors.forename: J H
authors.initials: JH
authors.lastname: Lee
authors.forename: Y H
authors.initials: YH
authors.lastname: Lee
mesh_terms: D000368:Aged; D005138:Eyebrows / Q000254:growth & development; D051521:Fibroblast Growth Factor 5 / Q000235:genetics; D051523:Fibroblast Growth Factor 7 / Q000235:genetics; D015870:Gene Expression; D006197:Hair / Q000254:growth & development*; D006200:Hair Color / Q000235:genetics*; D006801:Humans; D007150:Immunohistochemistry; D053564:Keratins, Hair-Specific / Q000235:genetics*; D008297:Male; D008875:Middle Aged; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015854:Up-Regulation
chemical_list: C496449:FGF5 protein, human; C496453:FGF7 protein, human; D053564:Keratins, Hair-Specific; D051523:Fibroblast Growth Factor 7; D051521:Fibroblast Growth Factor 5