THE FACETED S100B PROTEIN: THE JEKYLL/HYDE SIDE

F. Michetti | LUM University Casamassima, Genes Company, Roma, Italy

S100B is a calcium-binding protein originally isolated in the nervous system, where it is concentrated in astrocytes. It has also been found in definite extra-neural cell types, although at a lower level, excepting adipocytes, which constitute an intriguing site of concentration for the protein. While many functions have been attributed to the protein, at present it appears to have a double concentration-dependent role. A trophic role at low (nM) physiological concentration (Jekyll side), and a toxic role at high (mM) pathological concentration (Hyde side). This latter aspect, understandably, mainly attracted the attention of the scientific community, which also individuated the protein levels in biological fluids as a biomarker, and an effector/therapeutic target of active disorders, mainly of the nervous system for review.¹ Thus, the trophic physiological role of the protein has been in fact disregarded, although it appears to deserve primary attention. In particular, after the indication that the protein is a natural constituent of milk, more recent discovery indicated that it is also a natural constituent of commonly used healthy aliments, such as vegetables, and its possible nutrient function is explained by its interaction with microbiota. In this respect, its presence in enteroglial cells, which essentially play a role similar to astrocytes in the enteric nervous system, deserves attention susceptible of interesting and unexpected developments (for review²).