Nonsteroidal anti-inflammatory drugs modulate cellular glycosaminoglycan synthesis by affecting EGFR and PI3K signaling pathways

In this report, selected non-steroidal anti-inflammatory drugs (NSAIDs), indomethacin and nimesulide, and analgesics acetaminophen, alone, as well as in combination with isoflavone genistein as potential glycosaminoglycan (GAG) metabolism modulators were considered for the treatment of mucopolysaccharidoses (MPSs) with neurological symptoms due to the effective blood-brain barrier\ud (BBB) penetration properties of these compounds. We found that indomethacin and nimesulide, but not acetaminophen, inhibited GAG synthesis in fibroblasts significantly, while the most pronounced impairment of glycosaminoglycan production was observed after exposure to the mixture of nimesulide and genistein. Phosphorylation of the EGF receptor (EGFR) was inhibited even more effective in the presence of indomethacin and nimesulide than in the presence of genistein. When examined the activity of phosphatidylinositol-3-kinase (PI3K) production, we observed its most significant decrease in the case of fibroblast exposition to nimesulide, and afterwards to indomethacin and genistein mix, rather than indomethacin used alone. Some effects on expression of individual GAG metabolism-related and lysosomal function genes, and significant activity modulation of a number of genes involved in intracellular signal transduction pathways and metabolism of DNA and proteins were detected. This study documents that NSAIDs, and their mixtures with genistein modulate cellular glycosaminoglycan synthesis by affecting EGFR and PI3K signaling pathways

Modulation of expression of genes involved in glycosaminoglycan metabolism and lysosome biogenesis by flavonoids

Flavonoids were found previously to modulate efficiency of synthesis of glycosaminoglycans (GAGs), compounds which are accumulated in cells of patients suffering from mucopolysaccharidoses (MPSs). The aim of this work was to determine effects of different flavonoids (genistein, kaempferol, daidzein) used alone or in combinations, on expression of genes coding for proteins involved in GAG metabolism. Analyses with DNA microarray, followed by real-time qRT-PCR revealed that genistein, kaempferol and combination of these two compounds induced dose- and time-dependent remarkable alterations in transcript profiles of GAG metabolism genes in cultures of wild-type human dermal fibroblasts (HDFa). Interestingly, effects of the mixture of genistein and kaempferol were stronger than those revealed by any of these compounds used alone. Similarly, the most effective reduction in levels of GAG production, in both HDFa and MPS II cells, was observed in the presence of genistein, keampferol and combination of these compounds. Forty five genes were chosen for further verification not only in HDFa, but also inMPS II fibroblasts by using real-time qRT-PCR. Despite effects on GAG metabolism-related genes, we found that genistein, kaempferol and mixture of these compounds significantly stimulated expression of TFEB. Additionally, a decrease inMTOR transcript level was observed at these conditions

Hyperhomocysteinemia - important risk factor for ischemic stroke

Udary mózgu są trzecią co do częstości przyczyną śmierci oraz najczęstszą przyczyną inwalidztwa w populacji osób dorosłych. Etiologia udarów często pozostaje nieustalona. Wśród licznych czynników etiopatogenetycznych udaru mózgu należy uwzględnić hiperhomocysteinemię, która odgrywa istotną rolę w patogenezie udaru mózgu jako czynnik wywołujący proces miażdżycowy i wpływający na zaburzenia krzepnięcia. Metabolizm homocysteiny zależy od wielu czynników, takich jak: stężenia kwasu foliowego, witamin B6 i B12 lub mutacji genów kodujących metabolizm homocysteiny: reduktazy N5, N10-metylenotetrahydrofolianowej (MTHFR, methylenetetrahydrofolate reductase), β-syntazy cystationinowej (CBS, cystationine β syntase) i syntazy metioninowej (MS, metionine syntase). Ocena stężenia homocysteiny u pacjentów z chorobami naczyniowymi, w tym u chorych z udarem mózgu, nie tylko poszerza wiedzę o etiologii i mechanizmach udarów mózgu, ale w sposób praktyczny wpływa na ich leczenie i zapobieganie im.Hyperhomocysteinemia is emerging as possible risk factor for cardiovascular disease, including cerebral stroke. Stroke is one of the leading causes of mortality and disability in Poland. The etiology of stroke is often unknown; it has been estimated that etiology and pathophysiology in more that 40% of strokes remains unexplained. Hyperhomocysteinemia is considered a modifiable risk factor for stroke, possibly because of atherogenic and prothrombotic mechanism. Both, genetics and environmental (e.g. dietary intake of folic acid and B vitamins) factors affects homocysteine level. One of the most common genetics defects of homocysteine metabolism is a mutation in the enzyme methylenetetrahydrofolate reductase (MTHFR), metionine syntase (MS) and cystationine beta syntase (CBS). Identification of the role of hyperhomocysteinemia as the modifiable risk factor for stroke may lead to more effective prevention of stroke through dietary and pharmacological modification of homocysteine level

Identification of QTLs affecting scopolin and scopoletin biosynthesis in Arabidopsis thaliana

Scopoletin and its glucoside scopolin are important secondary metabolites synthesized in plants as a defense mechanism against various environmental stresses. They belong to coumarins, a class of phytochemicals with significant biological activities that is widely used in medical application and cosmetics industry. Although numerous studies showed that a variety of coumarins occurs naturally in several plant species, the details of coumarins biosynthesis and its regulation is not well understood. It was shown previously that coumarins (predominantly scopolin and scopoletin) occur in Arabidopsis thaliana (Arabidopsis) roots, but until now nothing is known about natural variation of their accumulation in this model plant. Therefore, the genetic architecture of coumarins biosynthesis in Arabidopsis has not been studied before.Here, the variation in scopolin and scopoletin content was assessed by comparing seven Arabidopsis accessions. Subsequently, a quantitative trait locus (QTL) mapping was performed with an Advanced Intercross Recombinant Inbred Lines (AI-RILs) mapping population EstC (Est-1 × Col). In order to reveal the genetic basis of both scopolin and scopoletin biosynthesis, two sets of methanol extracts were made from Arabidopsis roots and one set was additionally subjected to enzymatic hydrolysis prior to quantification done by high-performance liquid chromatography (HPLC). We identified one QTL for scopolin and five QTLs for scopoletin accumulation. The identified QTLs explained 13.86% and 37.60% of the observed phenotypic variation in scopolin and scopoletin content, respectively. In silico analysis of genes located in the associated QTL intervals identified a number of possible candidate genes involved in coumarins biosynthesis.Together, our results demonstrate for the first time that Arabidopsis is an excellent model for studying the genetic and molecular basis of natural variation in coumarins biosynthesis in plants. It additionally provides a basis for fine mapping and cloning of the genes involved in scopolin and scopoletin biosynthesis. Importantly, we have identified new loci for this biosynthetic process

Analysis of the link between the redox state and enzymatic activity of the HtrA (DegP) protein from Escherichia coli

Bacterial HtrAs are proteases engaged in extracytoplasmic activities during stressful conditions and pathogenesis. A model prokaryotic HtrA (HtrA/DegP from Escherichia coli) requires activation to cleave its substrates efficiently. In the inactive state of the enzyme, one of the regulatory loops, termed LA, forms inhibitory contacts in the area of the active center. Reduction of the disulfide bond located in the middle of LA stimulates HtrA activity in vivo suggesting that this S-S bond may play a regulatory role, although the mechanism of this stimulation is not known. Here, we show that HtrA lacking an S-S bridge cleaved a model peptide substrate more efficiently and exhibited a higher affinity for a protein substrate. An LA loop lacking the disulfide was more exposed to the solvent; hence, at least some of the interactions involving this loop must have been disturbed. The protein without S-S bonds demonstrated lower thermal stability and was more easily converted to a dodecameric active oligomeric form. Thus, the lack of the disulfide within LA affected the stability and the overall structure of the HtrA molecule. In this study, we have also demonstrated that in vitro human thioredoxin 1 is able to reduce HtrA; thus, reduction of HtrA can be performed enzymatically

The model homologue of the partially defective human 5,10-methylenetetrahydrofolate reductase, considered as a risk factor for stroke due to increased homocysteine level, can be protected and reactivated by heat shock proteins

The A222V substitution in the human MTHFR gene product (5,10-methylenetetrahydrofolate reductase) is responsible for a decreased activity of this enzyme. This may cause an increased homocysteine level, considered as a risk factor for arteriosclerosis and stroke. The bacterial homologue of the human enzyme, MetF, has been found to be a useful model in genetic and biochemical studies. The similarity of Escherichia coli MetF and human MTHFR proteins is so high that particular mutations in the corresponding human gene can be reflected by the bacterial mutants. For example, the A222V substitution in MTHFR (caused by the C667T substitution in the MTHFR gene) can be ascribed to the A117V substitution in MetF. Here, it is reported that a temperature-sensitive MetF117 (A117V) protein can be partially protected from a thermal inactivation by the heat shock proteins from the Hsp70/100 systems. Moreover, activity of the thermally denatured enzyme can be partially restored by the same heat shock proteins. High temperature protein G (HtpG) had no effect on MetF117 activity in both experimental systems. The presented results indicate that functions of heat shock proteins may be required for maintenance of the MetF117 function. This may have implications for the mechanisms of arteriosclerosis and stroke, especially in the light of previous findings that the A222V MTHFR polymorphism may be a risk factor for stroke, as well as recently published results which demonstrated the increased levels of antibodies against heat shock proteins in stroke patients

Glycosaminoglycans and mucopolysaccharidosis type III

Mucopolysaccharidosis type III (MPS III), or Sanfilippo syndrome, is a lysosomal storage disease in which heparan sulfate is accumulated in lysosomes, as well as outside of cells, as the primary storage material. This disease is a complex of four conditions caused by dysfunctions of one of genes coding for lysosomal enzymes involved in degradation of heparan sulfate: SGSH (coding for heparan N-sulfatase) – causing MPS IIIA, NAGLU (coding for -N-acetylglucosaminidase) - causing MPS IIIB, HGSNAT (coding for acetyl CoA -glucosaminide acetyltransferase) - causing MPS IIIC), and GNS (coding for N-acetylglucosamine-6-sulfatase) – causing MPS IIID. The primary storage is responsible for some disease symptoms, but other arise as a result of secondary storage, including glycosphingolipids, and subsequent processes, like oxidative stress and neuroinflammation. Central nervous system is predominantly affected in all subtypes of MPS III. Heparan sulfate and its derivatives are the most commonly used biomarkers for diagnosis and prediction procedures. Currently, there is no therapy for Sanfilippo syndrome, however, clinical trials are ongoing for enzyme replacement therapy, gene therapy and substrate reduction therapy (particularly gene expression-targeted isoflavone therapy)

Evidence for interactions between homocysteine and genistein: insights into stroke risk and potential treatment

Elevated plasma homocysteine (2-amino-4- sulfanylbutanoic acid) level is a risk factor for stroke. Moreover, it has been suggested that high levels of homocysteine in the acute phase of an ischemic stroke can predict mortality, especially in stroke patients with the large-vessel atherosclerosis subtype. In clinical studies, supplementation with genistein(5, 7-dihydroxy-3- (4-hydroxyphenyl)-4H-1-benzopyran-4-one) decreased plasma homocysteine levels considerably. Therefore, genistein could be considered as a potential drug for prevention and/or treatment of stroke. However, the mechanism of the effect of genistein on homocysteine level remains to be elucidated. In this report, direct functional interactions between homocysteine and genistein are demonstrated in in vitro experimental systems for determination of methylenetetrahydrofolate reductase (MetF) and glutathione peroxidase(GPx) activities, reconstructed with purified compounds, and in a simple in vivo system, based on measurement of growth rate of Vibrio harveyi and Bacillus subtilis cultures. Results of molecular modelling indicated that homocysteine can directly interact with genistein. Therefore, genisteinmediated decrease in plasma levels of homocysteine, and alleviation of biochemical and physiological effects of one of these compounds by another, might be ascribed to formation of homocysteine-genistein complexes in which biological activities of these molecules are abolished or alleviated