The distribution of ? 2 ? 1, ? 3 ? 1 and ? 6 ? 4 integrins identifies distinct subpopulations of basal keratinocytes in the outer root sheath of the human anagen hair follicle

Abstract

The human hair follicle is composed of different concentric compartments, which reflect different programmes of differentiation. Using monoclonal antibodies against alpha 2 beta 1 and alpha 3 beta 1 integrins we demonstrated a shift in their expression, from a basolateral distribution in the basal cells of the lower outer root sheath, to an apicolateral expression in the upper outer root sheath, as in epidermis. This shift takes place in a transition zone, localized to the midpart of the follicle. The distinct basolateral distribution of alpha 2 beta 1 and alpha 3 beta 1 integrins in the lower portion of the outer root sheath coincides with the presence of basal cell protrusions and is probably linked to the presence of the vitreous membrane which surrounds the bottom part of the anagen human hair follicle. Moreover, we showed that the expression of alpha 6 beta 4 integrin is discontinuous along the hair follicle and coincides with that of laminin 5. Together these results establish that within a given compartment-namely the outer root sheath-several domains can be clearly identified, which probably reflect the onset of successive differentiation pathways along the hair follicle.

Dissociation of the complex between CD151 and laminin-binding integrins permits migration of epithelial cells

“…Laminin 5, its binding integrins and CD151 were stained by indirect immunofluorescence in human skin cryosections containing both interfollicular epidermis and hair follicles. In agreement with previous results [36], laminin 5 (Fig. 10A), integrin α6 (Fig.…”

Integrin-linked kinase is required for epidermal and hair follicle morphogenesis

“…The α2β1 is found around the entire basal keratinocytes, where it is thought to mediate cell–cell interactions. ORS cells express α2β1, α3β1, and α6β4 integrins at different levels according to the region of the HF (Commo and Bernard, 1997). In vitro studies with keratinocytes and genetic manipulations in mice revealed that β1 integrins regulate adhesion and differentiation of epidermal cells and play an essential role for hair germ invagination, ORS cell migration, and sustained HM proliferation during HF morphogenesis (Brakebusch et al, 2000; Raghavan et al, 2000; Watt, 2002; Grose et al, 2002).…”

Alterated integrin expression in lichen planopilaris

“…The outer root sheath cells interact with the basement membrane mainly via α 3 β 1 and α 6 β 4 integrins, which are expressed at different levels in different regions of the hair follicle [7]. …”