Iron overload disorders are characterized by the body's inability to regulate iron absorption and its storage which can lead to organ failures. Accumulated evidence has revealed that hepcidin, the master regulator of iron homeostasis, is negatively modulated by TMPRSS6 (matriptase-2), a liver-specific type II transmembrane serine protease (TTSP). Here, we report that treatment with a peptidomimetic inhibitor affecting TMPRSS6 activity increases hepcidin production in hepatic cells. Moreover, similar effects were observed when using non-peptidic inhibitors obtained through optimization of hits from high-throughput screening. Using HepG2 cells and human primary hepatocytes, we show that TMPRSS6 inhibitors block TMPRSS6-dependent hemojuvelin cleavage and increase HAMP expression and levels of secreted hepcidin.
Drug Evaluation, Preclinical , Hepcidins/metabolism , Membrane Proteins/antagonists & inhibitors , Serine Proteinase Inhibitors/chemistry , Benzothiazoles/chemistry , Binding Sites , Catalytic Domain , Cell Survival/drug effects , GPI-Linked Proteins/metabolism , Hemochromatosis Protein/metabolism , Hep G2 Cells , Hepatocytes/cytology , Hepatocytes/metabolism , High-Throughput Screening Assays , Humans , Iron/metabolism , Membrane Proteins/metabolism , Molecular Dynamics Simulation , Peptidomimetics , Proteolysis/drug effects , Serine Endopeptidases/chemistry , Serine Endopeptidases/metabolism , Serine Proteinase Inhibitors/metabolism , Serine Proteinase Inhibitors/pharmacology , Up-Regulation/drug effects
Matriptase-2, a type II transmembrane serine protease (TTSP), is expressed in the liver and regulates iron homeostasis via the cleavage of hemojuvelin. Matriptase-2 emerges as an attractive target for the treatment of conditions associated with iron overload, such as hemochromatosis or beta-thalassemia. Starting from the crystal structure of its closest homolog matriptase, we constructed a homology model of matriptase-2 in order to further optimize the selectivity of serine trap peptidomimetic inhibitors for matriptase-2 vs matriptase. Careful modifications of the P4, P3 and P2 positions with the help of unnatural amino acids led to a thorough understanding of Structure-Activity Relationship and a >60-fold increase in selectivity for matriptase-2 vs matriptase. Additionally, the introduction of unnatural amino acids led to significant increases in plasma stability. Such compounds represent useful pharmacological tools to test matriptase-2 inhibition in a context of iron overload.
Amino Acids/chemistry , Enzyme Inhibitors/pharmacology , Iron Overload/drug therapy , Membrane Proteins/antagonists & inhibitors , Enzyme Inhibitors/chemical synthesis , Homeostasis/drug effects , Humans , Iron/metabolism , Models, Molecular , Sensitivity and Specificity , Serine Endopeptidases , Structure-Activity Relationship
A one-pot environmentally friendly transamidation of ω-3 fatty acid ethyl esters to amides and mono- or diacylglycerols was investigated via the use of a polymer-supported lipase. The method was used to synthesize a library of fatty acid monoglyceryl esters and amides. These new derivatives were found to have potent growth inhibition effects against A549 lung cancer cells.
Amides/chemistry , Fatty Acids, Unsaturated/chemistry , Amides/chemical synthesis , Amides/toxicity , Cell Line, Tumor , Cell Proliferation/drug effects , Enzymes, Immobilized/chemistry , Enzymes, Immobilized/metabolism , Esters , Fatty Acids, Unsaturated/chemical synthesis , Fatty Acids, Unsaturated/toxicity , Humans , Lipase/chemistry , Lipase/metabolism , Structure-Activity Relationship
Orthostatic hypotension is frequently observed in the elderly population and has been previously identified as a significant risk factor for increased mortality. The link between this condition and increased mortality could be due to an abnormal circadian pattern of blood pressure. The absence of a physiological nocturnal decrease in blood pressure is termed the non-dipping pattern. This abnormality is relatively frequent in elderly people suffering from orthostatic hypotension, but its prevalence in the diabetic geriatric population is unknown. The purpose of this study is to compare blood pressure profiles on ambulatory blood pressure monitoring (ABPM) in a sample of elderly diabetic subjects suffering from orthostatic hypotension with those without postural hypotension. One hundred and ninety-eight patients were recruited by mail. The presence or absence of orthostatic hypotension was determined. They all subsequently underwent ABPM. One hundred and thirty-one of our subjects (68%) suffered from orthostatic hypotension; of these, 76% had a non-dipping pattern on ABPM, compared with 74% of the subjects not suffering from orthostatic hypotension (Pâ=âNS). This study thus demonstrates the high prevalence of orthostatic hypotension in an elderly diabetic population. On the other hand, we could not demonstrate a correlation between the non-dipping pattern and the presence of orthostatic hypotension. This is in contrast with previous work done in a non-diabetic elderly population. Further studies are needed to determine the effect of diabetes on blood pressure.
Blood Pressure Monitoring, Ambulatory , Blood Pressure/physiology , Circadian Rhythm/physiology , Diabetes Mellitus, Type 2/diagnosis , Diabetes Mellitus, Type 2/physiopathology , Hypotension, Orthostatic/diagnosis , Hypotension, Orthostatic/physiopathology , Aged , Aged, 80 and over , Cross-Sectional Studies , Diabetes Mellitus, Type 2/epidemiology , Female , Humans , Hypotension, Orthostatic/epidemiology , Male , Quebec , Statistics as Topic
