Comparison of extracellular matrix enrichment protocols for the improved characterization of the skin matrisome by mass spectrometry.

A striking feature of skin organization is that the extracellular matrix (ECM) occupies a larger volume than the cells. Skin ECM also directly contributes to aging and most cutaneous diseases. In recent years, specific ECM enrichment protocols combined with in silico approaches allowed the proteomic description of the matrisome of various organs and tumor samples. Nevertheless, the skin matrisome remains under-studied and protocols allowing the efficient recovery of the diverse ECM found in skin are still to be described. Here, we compared four protocols allowing the enrichment of ECM proteins from adult mouse back skin and found that all protocols led to a significant enrichment (up to 65%) of matrisome proteins when compared to total skin lysates. The protocols based on decellularization and solubility profiling gave the best results in terms of numbers of proteins identified and confirmed that skin matrisome proteins exhibit very diverse solubility and abundance profiles. We also report the first description of the skin matrisome of healthy adult mice that includes 236 proteins comprising 95 core matrisome proteins and 141 associated matrisome proteins. These results provide a reliable basis for future characterizations of skin ECM proteins and their dysregulations in disease-specific contexts. SIGNIFICANCE: Extracellular matrix proteins are key players in skin physiopathology and have been involved in several diseases such as genetic disorders, wound healing defects, scleroderma and skin carcinoma. However, skin ECM proteins are numerous, diverse and challenging to analyze by mass spectrometry due to the multiplicity of their post-translational modifications and to the heterogeneity of their solubility profiles. Here, we performed the thorough evaluation of four ECM enrichment protocols compatible with the proteomic analysis of mouse back skin and provide the first description of the adult mouse skin matrisome in homeostasis conditions. Our work will greatly facilitate the future characterization of skin ECM alterations in preclinical mouse models and will inspire new optimizations to analyze the skin matrisome of other species and of human clinical samples.