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Terminal differentiation of the epidermis is an oriented process during which keratinocytes of the innermost basal layer undergo a series of metabolic and structural changes as they migrate toward the skin surface. At the latest stage, they undergo cornification, a programmed cell death leading to the transformation of granular keratinocytes, the last living cells in the program of keratinocyte terminal differentiation, into corneocyte. The cornified layer, resulting from the stacking of corneocytes, is essential for the main function of epidermis, the barrier function, vital for the organism. Thus at the granular keratinocyte stage culminates the production of the cornified envelope precursors as well as other cellular components specific for the stratum corneum.
Our group works on the structural, cellular and molecular basis of the barrier function of the stratum corneum. More particularly, we are interested in two essential functional properties of the epidermal barrier: the stratum corneum cohesion and its mechanical resistance, studies through investigation on the cornified envelope and an adhesive protein of the corneodesmosome, corneodesmosin (CDSN).
The essential role of the epidermal barrier is largely demonstrated by the consequences of its alteration during various dermatological diseases, especially numerous Genodermatoses such as Lamellar Ichthyosis, X-linked Ichthyosis or the Netherton Syndrome, which are related to mutations of genes expressed only at late stages of keratinocyte differentiation.
A second objective of the group is to decipher the pathophysiology of some yet poorly characterized ichthyoses, including the Peeling Skin Disease, a rare disease that was recently shown to result from nonsense mutation in CDSN. In this goal, the group closely collaborates with the “Centre de Référence des Maladies Rares de la Peau” (CRMRP) of Toulouse and Bordeaux university hospitals.