Caroline Delattre

Influence of calcium on the proteolytic degradation of the calmodulin-like skin protein (calmodulin-like protein 5) in psoriatic epidermis.

Abstract:  The calmodulin‐like skin protein (CLSP) or so‐called calmodulin‐like protein 5, a recently discovered skin‐specific calcium‐binding protein, is closely related to keratinocyte differentiation. The 16‐kDa protein is proteolytically degraded in the upper layers of the stratum corneum (SC) of healthy skin. With the use of specific new monoclonal antibodies to CLSP, we were able to demonstrate that the abnormal elevated levels of CLSP, characteristic of psoriatic epidermis, were probably not due to an overexpression of the protein, but most likely the result of its non‐degradation. Further in vitro experiments using recombinant CLSP and in situ data clearly showed that calcium protected and chelator accelerated CLSP degradation. These data indicate that CLSP degradation in the SC of psoriatic skin might be hindered by the abnormally elevated calcium concentration. No degradation of CLSP in psoriatic epidermis keeping its ability to bind protein as transglutaminase 3 may have a physiological role in skin diseases such as psoriasis.

Proteomic analysis identifies new biomarkers for postmenopausal and dry skin

Abstract:  A proteomic analysis of stratum corneum (SC) samples of normal healthy skin revealed the presence of more than 70 proteins by 2D electrophoresis. The majority of these proteins to our knowledge have not yet been described in normal SC. We analysed by Western blot the levels of 25 proteins in the SC taken from postmenopausal and dry skin compared with young and normal skin, respectively. In postmenopausal skin, there was a significantly increased amount of heat shock protein 27, plakoglobin and desmoglein 1, whereas transglutaminase 3, apolipoprotein D and acid ceramidase levels were significantly reduced compared with the SC of young skin. We confirmed corneodesmosin as a marker of dry skin. In addition, we showed for the first time that the levels of both phosphatidylethanolamine‐binding protein 1 and annexin A2 were significantly increased in the SC of dry skin compared with the SC of normal skin. These results suggest that a proteomic analysis of the SC obtained using a non‐invasive varnish stripping method is an attractive alternative to invasive methods to better characterize changes in the physiology of ageing and dry skin.