Subunit-selective proteasome inhibitors are valuable tools to assess the biological and medicinal relevance of individual proteasome active sites. Whereas the inhibitors for the β1c, β1i, β5c, and... Show more Subunit-selective proteasome inhibitors are valuable tools to assess the biological and medicinal relevance of individual proteasome active sites. Whereas the inhibitors for the β1c, β1i, β5c, and β5i subunits exploit the differences in the substrate-binding channels identified by X-ray crystallography, compounds selectively targeting β2c or β2i could not yet be rationally designed because of the high structural similarity of these two subunits. Here, we report the development, chemical synthesis, and biological screening of a compound library that led to the identification of the β2c- and β2i-selective compounds LU-002c (4; IC50 β2c: 8 nM, IC50 β2i/β2c: 40-fold) and LU-002i (5; IC50 β2i: 220 nM, IC50 β2c/β2i: 45-fold), respectively. Co-crystal structures with β2 humanized yeast proteasomes visualize protein–ligand interactions crucial for subunit specificity. Altogether, organic syntheses, activity-based protein profiling, yeast mutagenesis, and structural biology allowed us to decipher significant differences of β2 substrate-binding channels and to complete the set of subunit-selective proteasome inhibitors. Show less
The skin barrier function strongly relies on the outermost layer of the skin, the stratum corneum (SC), which consists of dead corneocytes embedded in a highly organized extracellular lipid matrix.... Show moreThe skin barrier function strongly relies on the outermost layer of the skin, the stratum corneum (SC), which consists of dead corneocytes embedded in a highly organized extracellular lipid matrix. The lipids are thought to play a crucial role in the skin barrier function. This lipid matrix consists mainly of ceramides, cholesterol and free fatty acids in an approximately equimolar ratio. Atopic eczema (AE) is a chronic relapsing inflammatory skin disease that is characterized by dryness, erythema and pruritus. AE patients have a decreased skin barrier function as monitored with transepidermal water loss. The main objective of this thesis is to determine the SC lipid composition, lipid organization and lipid/protein ratio in AE patients and control subjects and to determine how these changes are associated with the impaired skin barrier function and disease severity of AE patients. The studies demonstrate that there is an altered lipid composition and lipid/protein ratio in non-lesional as well as lesional SC of AE patients. The changes in lipid composition result in an altered lipid organization that is associated with an impaired skin barrier function in AE patients Show less
Janssens, M.; Smeden, J. van; Gooris, G.S.; Bras, W.; Portale, G.; Caspers, P.J.; ... ; Bouwstra, J.A. 2012
