Acute SARS-CoV-2 infection in pregnancy is associated with placental ACE-2 shedding

Human placental tissues have variable rates of SARS-CoV-2 invasion resulting in consistently low rates of fetal transmission suggesting a unique physiologic blockade against SARS-CoV-2. Angiotensin-converting enzyme (ACE)-2, the main receptor for SARS-CoV-2, is expressed as cell surface and soluble forms regulated by a metalloprotease cleavage enzyme, ADAM17. ACE-2 is expressed in the human placenta, but the regulation of placental ACE-2 expression in relation to timing of maternal SARS-CoV-2 infection in pregnancy is not well understood. In this study, we evaluated ACE-2 expression, ADAM17 activity and serum ACE-2 abundance in a cohort of matched villous placental and maternal serum samples from Control pregnancies (SARS-CoV-2 negative, n=8) and pregnancies affected by symptomatic maternal SARS-CoV-2 infections in the 2nd trimester (2ndTri COVID, n=8) and 3rd trimester (3rdTri COVID, n=8). In 3rdTri COVID as compared to control and 2ndTri-COVID villous placental tissues ACE-2 mRNA expression was remarkably elevated, however, ACE-2 protein expression was significantly decreased with a parallel increase in ADAM17 activity. Soluble ACE-2 was also significantly increased in the maternal serum from 3rdTri COVID infections as compared to control and 2ndTri-COVID pregnancies. These data suggest that in acute maternal SARS-CoV-2 infections, decreased placental ACE-2 protein may be the result of ACE-2 shedding. Overall, this work highlights the importance of ACE-2 for ongoing studies on SARS-CoV-2 responses at the maternal-fetal interface.

Influence of Extracts from Bark of Deciduous Trees on the Activity of the Amylolytic Enzyme - Alpha Amylase

The effect of water extracts obtained from bark of growing in Latvia and widely spread in Europe grey alder (Alnusincana), black alder (Alnusglutinosa) and aspen tree (Populustremula), on the amylase activity in human saliva was evaluated. The extracts were obtained using advanced ACE equipment and distilled hot water as a solvent. The total yields of extractives from bark were rather similar and varied from 16 % to 21 % based on dry bark. However, the content of proantocianidine and salicine derivatives used as diagnostic characteristic for evaluation of effect of extracts on activity of amylase – a glucose-polymers cleavage enzyme - differed significantly. The results of in-vitro tests realized using the model of human gastrointestinal pass have shown that the abovementioned extracts in micro dosages are able to increase significantly activity of amylase. However, this effect is dose dependent and when the dose is exceeded the opposite effect – inhibition of amylase activity - is observed. This effect is explained by increasing of proantocianidins component in the volume of the tested extract dose, because pure proantocianidins, isolated from grey alder bark significantly inhibited activity of amylase. The further investigation is necessary in order to estimate effective and safe dosages for application of extracts providing a guaranteed unambiguous effect of activation or inhibition of amylase activity.

Characterization of a Novel Lutein Cleavage Dioxygenase, EhLCD, from Enterobacter hormaechei YT-3 for the Enzymatic Synthesis of 3-Hydroxy-β-ionone from Lutein

3-Hydroxy-β-ionone, a flavor and fragrance compound with fruity violet-like characteristics, is widely applied in foodstuff and beverages, and is currently produced using synthetic chemistry. In this study, a novel lutein cleavage enzyme (EhLCD) was purified and characterized from Enterobacter hormaechei YT-3 to convert lutein to 3-hydroxy-β-ionone. Enzyme EhLCD was purified to homogeneity by ammonium sulfate precipitation, Q-Sepharose, phenyl-Sepharose, and Superdex 200 chromatography. The molecular mass of purified EhLCD, obtained by SDS-PAGE, was approximately 50 kDa. The enzyme exhibited the highest activity toward lutein, followed by zeaxanthin, β-cryptoxanthin, and β-carotene, suggesting that EhLCD exhibited higher catalytic efficiency for carotenoid substrates bearing 3-hydroxy-ionone rings. Isotope-labeling experiments showed that EhLCD incorporated oxygen from O2 into 3-hydroxy-β-ionone and followed a dioxygenase reaction mechanism for different carotenoid substrates. These results indicated that EhLCD is the first characterized bacterial lutein cleavage dioxygenase. Active EhLCD was also confirmed to be a Fe2+-dependent protein with 1 molar equivalent of non-haem Fe2+. The purified enzyme displayed optimal activity at 45 °C and pH 8.0. The optimum concentrations of the substrate, enzyme, and Tween 40 for 3-hydroxy-β-ionone production were 60 mM lutein/L, 1.5 U/mL, and 2% (w/v), respectively. Under optimum conditions, EhLCD produced 3-hydroxy-β-ionone (637.2 mg/L) in 60 min with a conversion of 87.0% (w/w), indicating that this enzyme is a potential candidate for the enzymatic synthesis of 3-hydroxy-β-ionone in biotechnological applications.

Phosphorylation and Glycosylation of Amyloid-β Protein Precursor: The Relationship to Trafficking and Cleavage in Alzheimer’s Disease

Alzheimer’s disease (AD) is a neurodegenerative disorder in the central nervous system, and this disease is characterized by extracellular senile plaques and intracellular neurofibrillary tangles. Amyloid-β (Aβ) peptide is the main constituent of senile plaques, and this peptide is derived from the amyloid-β protein precursor (AβPP) through the successive cleaving by β-site AβPP-cleavage enzyme 1 (BACE1) and γ-secretase. AβPP undergoes the progress of post-translational modifications, such as phosphorylation and glycosylation, which might affect the trafficking and the cleavage of AβPP. In the recent years, about 10 phosphorylation sites of AβPP were identified, and they play complex roles in glycosylation modification and cleavage of AβPP. In this article, we introduced the transport and the cleavage pathways of AβPP, then summarized the phosphorylation and glycosylation sites of AβPP, and further discussed the links and relationship between phosphorylation and glycosylation on the pathways of AβPP trafficking and cleavage in order to provide theoretical basis for AD research.

Differential Roles of Three Different Upper Pathway Meta Ring Cleavage Product Hydrolases in the Degradation of Dibenzo- p -dioxin and Dibenzofuran by Sphingomonas wittichii RW1

Sphingomonas wittichii RW1 grows on the two related compounds dibenzofuran (DBF) and dibenzo- p -dioxin (DXN) as the sole source of carbon. Previous work by others (P.V. Bunz, R. Falchetto, and A.M. Cook. Biodegradation 4:171-8, 1993, doi: 10.1007/BF00695119) identified two upper pathway meta cleavage product hydrolases (DxnB1 and DxnB2) active on the DBF upper pathway metabolite 2-hydroxy-6-oxo-6-(2-hydroxyphenyl)-hexa-2,4-dienoate. We took a physiological approach to determine the role of these two enzymes in the degradation of DBF and DXN by RW1. Single knockouts of either plasmid located dbfB1 or chromosome located dbfB2 had no effect on RW1 growth on either DBF or DXN. However, a double knockout lost the ability to grow on DBF but still grew normally on DXN demonstrating that DbfB1 and DbfB2 are the only hydrolases involved in the DBF upper pathway. Using a transcriptomic-guided approach we identified a constitutively expressed third hydrolase encoded by the chromosomally located SWIT0910 gene. Knockout of SWIT0910 resulted in a strain that no longer grows on DXN but still grows normally on DBF. Thus the DbfB1 and DbfB2 hydrolases function in the DBF but not the DXN catabolic pathway and the SWIT0190 hydrolase functions in the DXN but not the DBF catabolic pathway. Importance S. wittichii RW1 is one of only a few strains known to grow on DXN as the sole course of carbon. Much of the work deciphering the related RW1 DXN and DBF catabolic pathways has involved genome gazing, transcriptomics, proteomics, heterologous expression, and enzyme purification and characterization. Very little research has utilized physiological techniques to precisely dissect the genes and enzymes involved in DBF and DXN degradation. Previous work by others identified and extensively characterized two RW1 upper pathway hydrolases. Our present work demonstrates that these two enzymes are involved in DBF but not DXN degradation. In addition, our work identified a third constitutively expressed hydrolase that is involved in DXN but not DBF degradation. Combined with our previous work, this means that the RW1 DXN upper pathway involves genes from three very different locations in the genome: an initial plasmid-encoded dioxygenase and a ring cleavage enzyme and hydrolase encoded on opposite sides of the chromosome.

Biodegradation of p-xylene – A comparison for three Cold-active Pseudomonas strains

p-xylene is considered a recalcitrant compound despite the similar aromatic structure with BTE (Benzene, toluene, ethylbenzene). This study evaluated the biodegradation potential of p-xylene by three cold-active Pseudomonas strains (named Pseudomonas putida S2TR-01, Pseudomonas S2TR-20, and Pseudomonas S2TR-09). The catabolic genes (xylM, xylA and xylE) and their regulatory genes (xylR and xylS) were investigated for the p-xylene metabolism. The biodegradation results showed that only strain S2TR-09 was able to degrade 200 mg/L of p-xylene after 60 h at 15 °C. The gene expression study indicated that xylE (encoding catechol 2, 3-dioxygenase) represents the bottleneck for p-xylene biodegradation and lack of its expression leads to the accumulation of intermediates and inhibits biomass production as well as carbon recovery. The activity of xylene monooxygenase and catechol 2,3 dioxygenase was significantly high in P. azotoformans S2TR-09 (0.5 and 0.08 U/mg) in the presence of p-xylene. The expression of ring cleavage enzyme, its encoding genes (xylE), and its activator (xylS) enabled to link the differences in p-xylene metabolism and can be used as a novel biomarker for efficient p-xylene biodegradation in contaminated sites.

Depolymerization and conversion of lignin to value-added bioproducts by microbial and enzymatic catalysis

Lignin, the most abundant renewable aromatic compound in nature, is an excellent feedstock for value-added bioproducts manufacturing; while the intrinsic heterogeneity and recalcitrance of which hindered the efficient lignin biorefinery and utilization. Compared with chemical processing, bioprocessing with microbial and enzymatic catalysis is a clean and efficient method for lignin depolymerization and conversion. Generally, lignin bioprocessing involves lignin decomposition to lignin-based aromatics via extracellular microbial enzymes and further converted to value-added bioproducts through microbial metabolism. In the review, the most recent advances in degradation and conversion of lignin to value-added bioproducts catalyzed by microbes and enzymes were summarized. The lignin-degrading microorganisms of white-rot fungi, brown-rot fungi, soft-rot fungi, and bacteria under aerobic and anaerobic conditions were comparatively analyzed. The catalytic metabolism of the microbial lignin-degrading enzymes of laccase, lignin peroxidase, manganese peroxidase, biphenyl bond cleavage enzyme, versatile peroxidase, and β-etherize was discussed. The microbial metabolic process of H-lignin, G-lignin, S-lignin based derivatives, protocatechuic acid, and catechol was reviewed. Lignin was depolymerized to lignin-derived aromatic compounds by the secreted enzymes of fungi and bacteria, and the aromatics were converted to value-added compounds through microbial catalysis and metabolic engineering. The review also proposes new insights for future work to overcome the recalcitrance of lignin and convert it to value-added bioproducts by microbial and enzymatic catalysis.

In Search of New Therapeutics—Molecular Aspects of the PCOS Pathophysiology: Genetics, Hormones, Metabolism and Beyond

In a healthy female reproductive system, a subtle hormonal and metabolic dance leads to repetitive cyclic changes in the ovaries and uterus, which make an effective ovulation and potential implantation of an embryo possible. However, that is not so in the case of polycystic ovary syndrome (PCOS), in which case the central mechanism responsible for entraining hormonal and metabolic rhythms during the menstrual cycle is notably disrupted. In this review we provide a detailed description of the possible scenario of PCOS pathogenesis. We begin from the analysis of how a set of genetic disorders related to PCOS leads to particular malfunctions at a molecular level (e.g., increased enzyme activities of cytochrome P450 (CYP) type 17A1 (17α-hydroxylase), 3β-HSD type II and CYP type 11A1 (side-chain cleavage enzyme) in theca cells, or changes in the expression of aquaporins in granulosa cells) and discuss further cellular- and tissue-level consequences (e.g., anovulation, elevated levels of the advanced glycation end products in ovaries), which in turn lead to the observed subsequent systemic symptoms. Since gene-editing therapy is currently out of reach, herein special emphasis is placed on discussing what kinds of drug targets and which potentially active substances seem promising for an effective medication, acting on the primary causes of PCOS on a molecular level.

Shear stress activates ADAM10 sheddase to regulate Notch1 via the Piezo1 force sensor in endothelial cells

Mechanical force is a determinant of Notch signalling but the mechanism of force detection and its coupling to Notch are unclear. We propose a role for Piezo1 channels, which are mechanically-activated non-selective cation channels. In cultured microvascular endothelial cells, Piezo1 channel activation by either shear stress or a chemical agonist Yoda1 activated a disintegrin and metalloproteinase domain-containing protein 10 (ADAM10), a Ca2+-regulated transmembrane sheddase that mediates S2 Notch1 cleavage. Consistent with this observation, we found Piezo1-dependent increase in the abundance of Notch1 intracellular domain (NICD) that depended on ADAM10 and the downstream S3 cleavage enzyme, γ-secretase. Conditional endothelial-specific disruption of Piezo1 in adult mice suppressed the expression of multiple Notch1 target genes in hepatic vasculature, suggesting constitutive functional importance in vivo. The data suggest that Piezo1 is a mechanism conferring force sensitivity on ADAM10 and Notch1 with downstream consequences for sustained activation of Notch1 target genes and potentially other processes.