1995?Warmth shock protein 70 overexpression affects the response to ultraviolet light in murine fibroblasts. on NF-B and IB- pathway, whereas it downregulated the expression of cited proinflammatory cytokines, in lipopolysaccharides-treated keratinocytes. These results highlighted the ability of ectoine to protect cells from stress conditions and to prevent cell damage by maintaining an elevated level of the Hsp70. Overall, these data might suggest the use of this compatible solute in cosmetic and even pharmaceutical preparations aiming to activate a cytoprotective warmth shock response in human cells. INTRODUCTION Cells have developed a number of different strategies to deal with adverse changes in their environment. The environmental stressor may produce disease conditions associated mainly to protein damage and misfolded protein structures. To restore cellular homeostasis, some mechanisms of cellular defense might be activated by inducing the expression of various genes, including the acute phase genes and the heat shock proteins (Hsps) (Giannessi et al 2003). Increased expression of Hsps occurs when cells are exposed to a number of metabolic insults other than heating, including amino acid analogues, various heavy metals, brokers that modify protein sulfhydryls, numerous ionophores, and finally a number of other metabolic poisons (Welch 1992). In addition, Hsp synthesis was proved to be increased to safeguard prokaryotic or eukaryotic cells from numerous insults during periods of stress caused by infection, inflammation, or similar events (Zgel and Kaufmann 1999). The Hsp70 represents the most highly induced member of the stress protein family (Welch 1992). However, in humans, Hsp70 is not only elevated in response to stress but is also present at basal level in unstressed cells (Leung et al 1990). This protein is usually constitutively expressed in specific skin cells, such as epidermal keratinocytes, that provide a natural barrier against potential environmental stressful attacks. The expression of hsp70 may be further induced in epidermal keratinocytes by heat treatment, providing a state of resistance against the deleterious effects of solar ultraviolet SM-164 (UV)CB radiation (Souil et al 2001). The Hsp70B, another member of Hsp70 family, is strictly stress inducible and absent in unstressed cells (Leung et al 1990; Tavoria et al 1996). The sequences of the hsp70 (also known as hsp70A or hsp72) and hsp70B genes are similar, but they differ in terms of their pattern and extent of inducibility in response to conditions such as heat shock and CdCl2 treatment (Leung et al SM-164 1990). Recently, it has been demonstrated that laser photoirradiation markedly induced a long-lasting epidermal expression of hsp70 in normal rat skin (Souil et al 2001). It has been suggested that the laser-induced expression of hsp70 might contribute to improve tissue regeneration and wound healing. In addition, Hsp70 has also been associated with reduced inflammation and cell proliferation, suggesting an alternative role for this protein in cutaneous scarring (Laplante et al 1998). Procr This research aims to evaluate novel natural biomolecules regarding their ability SM-164 to activate the hsp70 and hsp70B. In particular, there is growing scientific interest in the study of compatible solutes isolated by halophilic eubacteria. These peculiar microorganisms are able to live in harsh environments, specifically they developed biochemical strategies to cope with high salinity SM-164 (up to 20% NaCl); in fact, they synthesize small organic molecules that can accumulate in the cytosol to balance the osmotic pressure of the external medium, without affecting the metabolism. Among these molecules, ectoine, a cyclic tetrahydropyrimidine (Fig 1), produced by ssp. and ssp., has been extensively characterized as a stabilizer for cells and biomolecules (Louis et al 1994). In addition to the biological function as an osmoprotectant, it was shown to preserve enzymes and whole cells in vitro against harmful conditions such as freezing, drying, SM-164 or heating (Lippert and Galinski 1992). Open in a separate window Fig 1. ?Ectoine structure However, the potential biotechnological applications of ectoine have still to be.