Assembly of hair keratins in transfected epithelial cells.
To define the interactions required for the filament assembly of differentiation-specific keratins, active copies of mouse hair keratin mHa1 and mHb4 genes were introduced into a rat kangaroo kidney epithelial cell line (PtK2) and a rat stratified squamous epithelial cell line (rat epidermal keratinocyte). In PtK2 transient transfectants, when introduced individually or in combination, mHa1 and mHb4 formed aggregates of ring-like structures of various sizes at the perinuclear region with no evidence of organization into a keratin network. These aggregates altered the distribution of the endogenous keratins and vimentin. In most of the cells carrying the ring-like structures of mHa1 and mHb4 around the nucleus, the endogenous keratin network collapsed and localized around the nucleus. Furthermore, the densely accumulated endogenous keratin surrounded the ring-like aggregates with partial co-localization. However, when transfected into the rat epidermal keratinocytes, mHa1 and mHb4 were able to co-localize with the well-developed cytoskeleton of endogenous keratins. These results showed that, in contrast to keratin pairs K5/K14 and K8/K18, the mHa1/mHb4 pair is unable to develop an extensive keratin network on its own and that there are possible differential abilities among these hair keratins and other keratins to form well-developed cytoplasmic networks.
Manabe
M
M
Department of Dermatology, Juntendo University School of Medicine, Hongo 3-1-3, Bunkyo-ku, Tokyo, 113, Japan. manabe@med.juntendo.ac.jp
Mizoguchi
M
M
Niwa
M
M
Bertolino
A P
AP
Ishidoh
K
K
Kominami
E
E
Ogawa
H
H
D000818:Animals; D002460:Cell Line; D004848:Epithelium / Q000378:metabolism; D019084:Fluorescent Antibody Technique, Indirect; D006197:Hair / Q000378:metabolism*; D007633:Keratins / Q000235:genetics / Q000378:metabolism*; D051379:Mice; D051381:Rats; D014162:Transfection
D007633:Keratins