title: Upregulation of class II beta-tubulin expression in differentiating keratinocytes.
abstract: The diverse functions of microtubules (MT) in different cells and tissues may be facilitated by compositional changes in tubulin isotypes. We obtained partial cDNA clones of class II beta-tubulin from a library of differentiating normal human epidermal keratinocytes (NHEK) cells, whereas screening via subtractive hybridization for genes involved in calcium-induced keratinocyte differentiation. Analysis of the isotypic composition of beta-tubulin from NHEK cells revealed elevations in class II beta-tubulin concentrations at both protein and message levels during cell differentiation, resulting in increased rates of incorporation of class II beta-tubulin into MT. Immunohistochemistry of normal and pathologic skin tissues showed that class II beta-tubulin occurred in the granular layer of the epidermis and in differentiated areas of carcinomas. Class II beta-tubulin was, however, not observed in the uppermost granular and cornified layers of normal epidermis. Further experiments showed that MT were likely to decay in the final stage of terminal differentiation during formation of the cornified envelope. Our results suggest that there is differential modulation of MT composition and stability during keratinocyte differentiation.
authors.affiliation: Department of Dermatology, School of Medicine, Chungnam National University, Deajeon, Korea.
authors.forename: Woong-Hee
authors.initials: WH
authors.lastname: Lee
authors.forename: Joo-Young
authors.initials: JY
authors.lastname: Kim
authors.forename: Young-Sik
authors.initials: YS
authors.lastname: Kim
authors.forename: Hye-Joon
authors.initials: HJ
authors.lastname: Song
authors.forename: Ki-Joon
authors.initials: KJ
authors.lastname: Song
authors.forename: Jin-Won
authors.initials: JW
authors.lastname: Song
authors.forename: Luck-Ju
authors.initials: LJ
authors.lastname: Baek
authors.forename: Eun-Young
authors.initials: EY
authors.lastname: Seo
authors.forename: Chang Deok
authors.initials: CD
authors.lastname: Kim
authors.forename: Chang-Duk
authors.initials: CD
authors.lastname: Kim
authors.forename: Jeung-Hoon
authors.initials: JH
authors.lastname: Lee
authors.forename: Sun-Ho
authors.initials: SH
authors.lastname: Kee
mesh_terms: D000107:Acetylation; D002454:Cell Differentiation / Q000502:physiology; D002478:Cells, Cultured; D015870:Gene Expression / Q000502:physiology; D006801:Humans; D015603:Keratinocytes / Q000166:cytology* / Q000502:physiology*; D008870:Microtubules / Q000502:physiology; D012867:Skin / Q000166:cytology / Q000378:metabolism; D014404:Tubulin / Q000235:genetics* / Q000378:metabolism; D015854:Up-Regulation / Q000502:physiology
chemical_list: D014404:Tubulin