Expression of the orphan protein Plet-1 during trichilemmal differentiation of anagen hair follicles.
The rat mAb 33A10 recognizes an antigen in a variety of mouse epithelial tissues. In this study, we investigated in detail the expression pattern of the 33A10-defined antigen in the hair follicle. We show that 33A10 reactivity is confined to the most differentiated keratinocytes of the outer root sheath (ORS), the companion layer (CL), and to cells of the sebaceous gland duct. In vitro, the 33A10-defined antigen is expressed in keratinocytes derived from the ORS and accumulates on induction of differentiation. Using microarray analysis and transient transfection approaches, we established that the 33A10-defined antigen is the orphan protein, Placenta-expressed transcript (Plet)-1. Biochemical data indicated that Plet-1 is a glycosylphosphatidylinositol-anchored glycoprotein with N-linked carbohydrates in addition to other posttranslational modifications. Although silencing of Plet-1 expression using stable RNA interference in ORS keratinocytes decreased cellular migration, it increased adhesion to collagens I and IV. Immunohistochemical analysis showed that Plet-1 was primarily localized at the leading edge of epidermal wounds, where keratinocytes contacted the eschar. The restricted localization in both differentiated ORS and CL cells contacting the hair fiber and epidermal wounds suggests a role for the Plet-1 protein in regulating the interaction of keratinocytes with inert tissues.
Division of Cell Biology, The Netherlands Cancer Institute, Plesmanlaan 121, Amsterdam, The Netherlands.
Karine
K
Raymond
Anja
A
Richter
Maaike
M
Kreft
Evelyne
E
Frijns
Hans
H
Janssen
Monique
M
Slijper
Silke
S
Praetzel-Wunder
Lutz
L
Langbein
Arnoud
A
Sonnenberg
D000818:Animals; D000911:Antibodies, Monoclonal / Q000378:metabolism; D019556:COS Cells; D002454:Cell Differentiation / Q000502:physiology*; D002465:Cell Movement / Q000502:physiology; D002522:Chlorocebus aethiops; D024042:Collagen Type I / Q000378:metabolism; D024141:Collagen Type IV / Q000378:metabolism; D018859:Hair Follicle / Q000166:cytology* / Q000378:metabolism*; D006801:Humans; D015603:Keratinocytes / Q000166:cytology / Q000378:metabolism; D051379:Mice; D041681:NIH 3T3 Cells; D011257:Pregnancy Proteins / Q000235:genetics / Q000276:immunology / Q000378:metabolism*
D000911:Antibodies, Monoclonal; D024042:Collagen Type I; D024141:Collagen Type IV; C526395:Plet-1 protein, mouse; D011257:Pregnancy Proteins