Elsevier

Differentiation

Volume 61, Issue 3, February 1997, Pages 187-194
Differentiation

ORIGINAL ARTICLE
Sequences and differential expression of three novel human type-II hair keratins

https://doi.org/10.1046/j.1432-0436.1997.6130187.xGet rights and content

Abstract

As part of a program designed to characterize human hair keratin genes and their expression, we present the cDNA sequences and deduced amino acid sequences of three type-II hair keratins hHb3, hHb5, and hHb6, which by virtue of their amino acid homologies are the orthologs of the previously described sheep wool keratins, K2.10, K2.12, and K.211 [29]. Amino acid sequences comparisons of these keratins, including the previously characterized human K2.9 ortholog hHb1, show extreme conservation not only in the α-helices but also in the aminoterminal and proximal carboxyterminal domains. They also demonstrate higher sequence relationships between hHb1, hHb3, and hHb6 as compared to hHb5, which exhibits chain-specific sequences in both the head and tail domains. In situ hybridization studies using specific 3′-probes for the four type-II hair keratins reveal sequential patterns of gene expression in human anagen follicles. Remarkably the onset of hHb5 mRNA synthesis occurs immediately above a small population of matrix cells at the base of the hair bulb and the trichocytes lining the dermal papilla. hHb5 mRNA synthesis extends upward through the matrix and ends in the lower part of the cortex of the hair shaft. In contrast, both hHb1 and hHb3 mRNA synthesis begins simultaneously in the cortex 10–15 cell layers above the apex of the dermal papilla, thus partially overlapping that of hHb5 but continuing to a point well beyond hHb5 in the upper cortex. Synthesis of hHb6 mRNA starts slightly higher than either hHb1 or hHb3 mRNA and proceeds much farther up into the keratogenous zone of the hair shaft. Our study demonstrates that the differentiation of human hair in terms of hair keratin expression begins much earlier than previously assumed, i.e. in lower matrix cells of the hair bulb. This early phase of hair differentiation is followed by a late cortical phase of terminal differentiation which comprises at least three type-II hair keratins in the zone of elongation and the keratogenous zone of the hair shaft.

References (44)

  • PS Kaytes et al.

    Hair-specific keratins: Characterization and expession of a mouse type I keratin gene

    J Invest Dermatol

    (1991)
  • N Kuruc et al.

    Synthesis of cytokeratin 13, a component characteristic of internal stratified epithelia, is not induced in human epidermal tumors

    Differentiation

    (1989)
  • I Moll et al.

    Cytokeratin analysis of pilomatrixoma: changes in cytokeratin-type expression during differentiation

    J Invest Dermatol

    (1988)
  • R Moll et al.

    The catalog of human cytokeratins: Patterns of expression in normal epithelia, tumors and cultured cells

    Cell

    (1982)
  • BC Powell et al.

    Characterization of a hair (wool) keratin intermediate filament gene domain

    J Invest Dermatol

    (1994)
  • A Rochat et al.

    Location of stem cells of human hair follicles by clonal analysis

    Cell

    (1994)
  • MA Rogers et al.

    Sequence data and chromosomal localization of human type I and type II hair keratin genes

    Exp Cell Res

    (1995)
  • MA Rogers et al.

    Genomic characterization of the human type I cuticular hair keratin hHa2 and identification of hHa5, an adjacent novel type-I hair keratin gene

    J Invest Dermatol

    (1996)
  • J Schweizer et al.

    Identification of murine type I keratin 9 (73 kDa) and its immunolocalization in neonatal and adult mouse foot sole epidermis

    Exp Cell Res

    (1989)
  • GD Weinstein et al.

    Cell proliferation kinetics in the human hair root

    J Invest Dermatol

    (1980)
  • H Winter et al.

    Sequence and expression of murine type I hair keratins mHa2 and mHa3

    Exp Cell Res

    (1994)
  • D-W Yu et al.

    Transient expression of mouse hair keratin in transfected HeLa cells: Interactions between “hard” and “soft” keratins

    J Invest Dermatol

    (1991)
  • Cited by (0)

    View full text