Rhomboids are intramembrane serine proteases with diverse physiological functions in organisms ranging from archaea to humans. Crystal structure analysis has provided a detailed understanding of the catalytic mechanism, and rhomboids have been implicated in various disease contexts. Unfortunately, the design of specific rhomboid inhibitors has lagged behind, and previously described small molecule inhibitors displayed insufficient potency and/or selectivity. Using a computer-aided approach, we focused on the discovery of novel scaffolds with reduced liabilities and the possibility for broad structural variations. Docking studies with the E. coli rhomboid GlpG indicated that 2-styryl substituted benzoxazinones might comprise novel rhomboid inhibitors. Protease in vitro assays confirmed activity of 2-styryl substituted benzoxazinones against GlpG but not against the soluble serine protease α-chymotrypsin. Furthermore, mass spectrometry analysis demonstrated covalent modification of the catalytic residue Ser201, corroborating the predicted mechanism of inhibition and the formation of an acyl enzyme intermediate. In conclusion, 2-styryl substituted benzoxazinones are a novel rhomboid inhibitor scaffold with ample opportunity for optimization.

• MeSH
• benzoxaziny chemická syntéza   chemie   MeSH
• chymotrypsin chemie   MeSH
• DNA vazebné proteiny antagonisté a inhibitory   chemie   genetika   MeSH
• Drosophila chemie   MeSH
• endopeptidasy chemie   genetika   MeSH
• enzymatické testy MeSH
• Escherichia coli enzymologie   MeSH
• inhibitory serinových proteinas chemická syntéza   chemie   MeSH
• katalytická doména MeSH
• lidé MeSH
• membránové proteiny antagonisté a inhibitory   chemie   genetika   MeSH
• mutace MeSH
• objevování léků MeSH
• proteiny Drosophily metabolismus   MeSH
• proteiny z Escherichia coli antagonisté a inhibitory   chemie   genetika   MeSH
• serin chemie   MeSH
• simulace molekulového dockingu MeSH
• skot MeSH
• styreny chemická syntéza   chemie   MeSH
• transformující růstový faktor alfa metabolismus   MeSH
• zvířata MeSH
• Check Tag
• lidé MeSH
• skot MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

INTRODUCTION: Competitive binding assays can be used to decipher not only the binding kinetics of studied ligands but also the binding site preference. Such assays are an essential step in the characterization of radioligands. However, the currently used competition assays require high concentrations of usually expensive ligands and still provide only binding site preference. By employing the time-resolved competition assay presented in this paper, binding characteristics including binding site preference can be obtained using less ligand. METHODS: To demonstrate the appropriateness of the time-resolved competition assay, we developed an assay in which the ligand binding was interrupted with a competitor. Experiments were performed on human carcinoma cell lines expressing epidermal growth factor receptor (EGFR). The targeting of the receptor was performed with radio-iodinated epidermal growth factor (EGF). The employed competitors involved either natural ligand transforming growth factor alpha (TGF-α) or anti-EGFR antibodies cetuximab and panitumumab targeting the same EGFR domain. RESULTS: Radio-iodinated EGF bound to EGFR was displaced with either low concentrations of cetuximab or high concentrations of panitumumab. In the case of TGF-α, we observed no competitive displacement of bound EGF at either high or low concentrations. When comparing the time-resolved competition assay with a manual competition assay, the resulting data of measured inhibition constants were in agreement. DISCUSSION: The results summarised in this study confirm the appropriateness of the time-resolved competition assay for assessing ligand binding properties. The assay has the potential to complement or replace conventional competition assays for determining binding site preference in the future.

• MeSH
• časové faktory MeSH
• epidermální růstový faktor chemie   metabolismus   MeSH
• erbB receptory antagonisté a inhibitory   chemie   metabolismus   MeSH
• humanizované monoklonální protilátky chemie   farmakologie   MeSH
• kompetitivní vazba účinky léků   MeSH
• lidé MeSH
• ligandy MeSH
• monoklonální protilátky chemie   farmakologie   MeSH
• nádorové buňky kultivované MeSH
• substrátová specifita MeSH
• transformující růstový faktor alfa chemie   metabolismus   MeSH
• vztah mezi dávkou a účinkem léčiva MeSH
• vztahy mezi strukturou a aktivitou MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

BACKGROUND: Ursodeoxycholic acid (UDCA) is used to treat primary biliary cirrhosis, intrahepatic cholestasis, and other cholestatic conditions. Although much has been learned about the molecular basis of the disease pathophysiology, our understanding of the effects of UDCA remains unclear. Possibly underlying its cytoprotective, anti-apoptotic, anti-oxidative effects, UDCA was reported to regulate the expression of TNFα and other inflammatory cytokines. However, it is not known if this effect involves also modulation of ADAM family of metalloproteinases, which are responsible for release of ectodomains of inflammatory cytokines from the cell surface. We hypothesized that UDCA modulates ADAM17 activity, resulting in amelioration of cholestasis in a murine model of bile duct ligation (BDL). METHODS: The effect of UDCA on ADAM17 activity was studied using the human liver hepatocellular carcinoma cell line HepG2. Untransfected cells or cells ectopically expressing human ADAM17 were cultured with or without UDCA and further activated using phorbol-12-myristate-13-acetate (PMA). The expression and release of ADAM17 substrates, TNFα, TGFα, and c-Met receptor (or its soluble form, sMet) were evaluated using ELISA and quantitative real-time (qRT) PCR. Immunoblotting analyses were conducted to evaluate expression and activation of ADAM17 as well as the level of ERK1/2 phosphorylation after UDCA treatment. The regulation of tissue inhibitor of metalloproteinases-1 (TIMP-1) by UDCA was studied using zymography and qRT-PCR. A mouse model of acute cholestasis was induced by common BDL technique, during which mice received daily orogastric gavage with either UDCA or vehicle only. Liver injury was quantified using alkaline phosphatase (ALP), relative liver weight, and confirmed by histological analysis. ADAM17 substrates in sera were assessed using a bead multiplex assay. RESULTS: UDCA decreases amount of shed TNFα, TGFα, and sMet in cell culture media and the phosphorylation of ERK1/2. These effects are mediated by the reduction of ADAM17 activity in PMA stimulated cells although the expression ADAM17 is not affected. UDCA reduced the level of the mature form of ADAM17. Moreover, UDCA regulates the expression of TIMP-1 and gelatinases activity in PMA stimulated cells. A BDL-induced acute cholangitis model was characterized by increased relative liver weight, serum levels of ALP, sMet, and loss of intracellular glycogen. UDCA administration significantly decreased ALP and sMet levels, and reduced relative liver weight. Furthermore, hepatocytes of UDCA-treated animals retained their metabolic activity as evidenced by the amount of glycogen storage. CONCLUSIONS: The beneficial effect of UDCA appears to be mediated in part by the inhibition of ADAM17 activation and, thus, the release of TNFα, a strong pro-inflammatory factor. The release of other ADAM17 substrates, TGFα and sMet, are also regulated this way, pointing to a general impact on the release of ADAM17 substrates, which are pivotal for liver regeneration and function. In parallel, UDCA upregulates TIMP-1 that in turn inhibits matrix metalloproteinases, which destroy the hepatic ECM in diseased liver. This control of extracellular matrix turnover represents an additional beneficial path of UDCA treatment.

• MeSH
• buňky Hep G2 MeSH
• cholagoga a choleretika farmakologie   MeSH
• cholestáza MeSH
• hepatocyty účinky léků   MeSH
• játra účinky léků   MeSH
• kyselina ursodeoxycholová farmakologie   MeSH
• lidé MeSH
• ligace MeSH
• MAP kinasový signální systém účinky léků   MeSH
• myši MeSH
• proteiny ADAM účinky léků   MeSH
• protoonkogenní proteiny c-met účinky léků   metabolismus   MeSH
• TNF-alfa účinky léků   metabolismus   MeSH
• transformující růstový faktor alfa účinky léků   metabolismus   MeSH
• žlučové cesty chirurgie   MeSH
• zvířata MeSH
• Check Tag
• lidé MeSH
• myši MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

• MeSH
• epidermální růstový faktor chemie   metabolismus   MeSH
• erythropoetin metabolismus   MeSH
• insulinu podobný růstový faktor I metabolismus   MeSH
• růstové látky MeSH
• transformující růstový faktor alfa chemie   metabolismus   MeSH
• transformující růstový faktor beta chemie   metabolismus   MeSH
• Publikační typ
• přehledy MeSH