Search results for "Molecular Bases of Disease"
showing 7 items of 7 documents
E4BP4/NFIL3 modulates the epigenetically repressed RAS effector RASSF8 function through histone methyltransferases
2018
RAS proteins are major human oncogenes, and most of the studies are focused on enzymatic RAS effectors. Recently, nonenzymatic RAS effectors (RASSF, RAS association domain family) have garnered special attention because of their tumor-suppressive properties in contrast to the oncogenic potential of the classical enzymatic RAS effectors. Whereas most members of RASSF family are deregulated by promoter hypermethylation, RASSF8 promoter remains unmethylated in many cancers but the mechanism(s) of its down-regulation remains unknown. Here, we unveil E4BP4 as a critical transcriptional modulator repressing RASSF8 expression through histone methyltransferases, G9a and SUV39H1. In line with these …
Modulating disease-relevant tau oligomeric strains by small molecules
2020
The pathological aggregation of tau plays an important role in Alzheimer's disease and many other related neurodegenerative diseases, collectively referred to as tauopathies. Recent evidence has demonstrated that tau oligomers, small and soluble prefibrillar aggregates, are highly toxic due to their strong ability to seed tau misfolding and propagate the pathology seen across different neurodegenerative diseases. We previously showed that novel curcumin derivatives affect preformed tau oligomer aggregation pathways by promoting the formation of more aggregated and nontoxic tau aggregates. To further investigate their therapeutic potential, we have extended our studies o disease-relevant bra…
New Hyperekplexia Mutations Provide Insight into Glycine Receptor Assembly, Trafficking, and Activation Mechanisms*
2013
Hyperekplexia is a syndrome of readily provoked startle responses, alongside episodic and generalized hypertonia, that presents within the first month of life. Inhibitory glycine receptors are pentameric ligand-gated ion channels with a definitive and clinically well stratified linkage to hyperekplexia. Most hyperekplexia cases are caused by mutations in the α1 subunit of the human glycine receptor (hGlyR) gene (GLRA1). Here we analyzed 68 new unrelated hyperekplexia probands for GLRA1 mutations and identified 19 mutations, of which 9 were novel. Electrophysiological analysis demonstrated that the dominant mutations p.Q226E, p.V280M, and p.R414H induced spontaneous channel activity, indicat…
Endothelial Dysfunction in Tristetraprolin-deficient Mice Is Not Caused by Enhanced Tumor Necrosis Factor-α Expression
2014
Cardiovascular events are important co-morbidities in patients with chronic inflammatory diseases like rheumatoid arthritis. Tristetraprolin (TTP) regulates pro-inflammatory processes through mRNA destabilization and therefore TTP-deficient mice (TTP(-/-) mice) develop a chronic inflammation resembling human rheumatoid arthritis. We used this mouse model to evaluate molecular signaling pathways contributing to the enhanced atherosclerotic risk in chronic inflammatory diseases. In the aorta of TTP(-/-) mice we observed elevated mRNA expression of known TTP targets like tumor necrosis factor-α (TNF-α) and macrophage inflammatory protein-1α, as well as of other pro-atherosclerotic mediators, l…
The Metalloprotease Meprin β Generates Amino Terminal-truncated Amyloid β Peptide Species
2012
The amyloid β (Aβ) peptide, which is abundantly found in the brains of patients suffering from Alzheimer disease, is central in the pathogenesis of this disease. Therefore, to understand the processing of the amyloid precursor protein (APP) is of critical importance. Recently, we demonstrated that the metalloprotease meprin β cleaves APP and liberates soluble N-terminal APP (N-APP) fragments. In this work, we present evidence that meprin β can also process APP in a manner reminiscent of β-secretase. We identified cleavage sites of meprin β in the amyloid β sequence of the wild type and Swedish mutant of APP at positions p1 and p2, thereby generating Aβ variants starting at the first or seco…
Regulation of Human Mitochondrial Aldehyde Dehydrogenase (ALDH-2) Activity by Electrophiles in Vitro
2011
Recently, mitochondrial aldehyde dehydrogenase (ALDH-2) was reported to reduce ischemic damage in an experimental myocardial infarction model. ALDH-2 activity is redox-sensitive. Therefore, we here compared effects of various electrophiles (organic nitrates, reactive fatty acid metabolites, or oxidants) on the activity of ALDH-2 with special emphasis on organic nitrate-induced inactivation of the enzyme, the biochemical correlate of nitrate tolerance. Recombinant human ALDH-2 was overexpressed in Escherichia coli; activity was determined with an HPLC-based assay, and reactive oxygen and nitrogen species formation was determined by chemiluminescence, fluorescence, protein tyrosine nitration,…
Stromal Interaction Molecule 1 (STIM1) Is Involved in the Regulation of Mitochondrial Shape and Bioenergetics and Plays a Role in Oxidative Stress
2012
Calcium ions are involved in a plethora of cellular functions including cell death and mitochondrial energy metabolism. Store-operated Ca(2+) entry over the plasma membrane is activated by depletion of intracellular Ca(2+) stores and is mediated by the sensor STIM1 and the channel ORAI1. We compared cell death susceptibility to oxidative stress in STIM1 knock-out and ORAI1 knockdown mouse embryonic fibroblasts and in knock-out cells with reconstituted wild type and dominant active STIM1. We show that STIM1 and ORAI1 deficiency renders cells more susceptible to oxidative stress, which can be rescued by STIM1 and ORAI1 overexpression. STIM1 knock-out mitochondria are tubular, have a higher Ca…