Refolding of ribonuclease A monitored by real-time photo-CIDNP NMR spectroscopy

Photo-CIDNP NMR spectroscopy is a powerful method for investigating the solvent accessibility of histidine, tyrosine and tryptophan residues in a protein. When coupled to real-time NMR, this technique allows changes in the environments of these residues to be used as a probe of protein folding. In this paper we describe experiments performed to monitor the refolding of ribonuclease A following dilution from a high concentration of chemical denaturant. These experiments provide a good example of the utility of this technique which provides information that is difficult to obtain by other biophysical methods. Real-time photo-CIDNP measurements yield residue-specific kinetic data pertaining to the folding reaction, interpreted in terms of current knowledge of the folding of bovine pancreatic ribonuclease A.     

Resveratrol counteracts gallic acid-induced down-regulation of gap-junction intercellular communication

Since reactive oxygen species (ROS) play a key role in carcinogenesis, many studies have focused on the chemopreventive activities of naturally occurring antioxidants. However, the possibility that different antioxidants in food exert opposing effects on carcinogenesis has not been adequately investigated. Gap-junction intercellular communication (GJIC), which is strongly related to carcinogenesis (particularly the tumor promotion stage), may be a suitable model for investigating the tumor-promoting and antitumor-promoting effects of phytochemicals. The present study investigated the possible combined effects of resveratrol and gallic acid (GA), which are major antioxidants in red wine, on GJIC in WB-F344 rat liver epithelial (RLE) cells. GA at 100 microM, but not resveratrol, inhibited GJIC and generated hydrogen peroxide. The GA-induced inhibition of GJIC was recovered by resveratrol, but only partially recovered by catalase. Resveratrol did not attenuate GA-induced generation of hydrogen peroxide, but it did block GA-induced phosphorylation of connexin 43 (Cx43), a key modulator of GJIC. Furthermore, resveratrol down-regulated GA-induced phosphorylation of extracellular signal-regulated kinase (ERK)1/2, one of the critical regulators of Cx43. However, catalase partially blocked the GA-induced phosphorylation of Cx43 and ERK1/2. Collectively, these findings suggest that the combined effects of red wine phenolic phytochemicals on GJIC and antioxidants differ in ROS-mediated carcinogenesis depending on their dosages and structures.     

ATG5 expression induced by MDMA (ecstasy), interferes with neuronal differentiation of neuroblastoma cells

The amphetamine derivative 3, 4-methylenedioxymethamphetamine (MDMA) has become a popular recreational drug, and has also been shown to cause serotonergic neurotoxicity. This report shows that MDMA impairs brain development in a whole mouse embryo culture. The results of quantitative real-time PCR analysis showed that autophagy-related protein 5 (Atg5) expression is elevated in mouse embryo and neuroblastoma cells after MDMA treatment. This elevated Atg5 expression interferes with the neuronal differentiation of neuroblastoma cells such as SH-SY5Y and PC12 cells. Thus, our results suggest that the use of MDMA during pregnancy may impair neuronal development via an induction of Atg5 expression.     

Carbachol regulates pacemaker activities in cultured interstitial cells of Cajal from the mouse small intestine

We studied the effect of carbachol on pacemaker currents in cultured interstitial cells of Cajal (ICC) from the mouse small intestine by muscarinic stimulation using a whole cell patch clamp technique and Ca²⁺-imaging. ICC generated periodic pacemaker potentials in the current-clamp mode and generated spontaneous inward pacemaker currents at a holding potential of–70 mV. Exposure to carbachol depolarized the membrane and produced tonic inward pacemaker currents with a decrease in the frequency and amplitude of the pacemaker currents. The effects of carbachol were blocked by 1-dimethyl-4-diphenylacetoxypiperidinium, a muscarinic M₃ receptor antagonist, but not by methotramine, a muscarinic M₂ receptor antagonist. Intracellular GDP-β-S suppressed the carbachol-induced effects. Carbachol-induced effects were blocked by external Na⁺-free solution and by flufenamic acid, a non-selective cation channel blocker, and in the presence of thapsigargin, a Ca²⁺-ATPase inhibitor in the endoplasmic reticulum. However, carbachol still produced tonic inward pacemaker currents with the removal of external Ca²⁺. In recording of intracellular Ca²⁺ concentrations using fluo 3-AM dye, carbachol increased intracellular Ca²⁺ concentrations with increasing of Ca²⁺ oscillations. These results suggest that carbachol modulates the pacemaker activity of ICC through the activation of non-selective cation channels via muscarinic M₃ receptors by a G-protein dependent intracellular Ca²⁺ release mechanism.     

Downstream process for the production of yeast extract using brewer's yeast cells

A downstream process was developed for the production of yeast extract from brewer's yeast cells. Various downstream processing conditions including clarification, debittering, and the Maillard reaction were considered in the development of the process. This simple and economic clarification process used flocculating agents, specifically calcium chloride (1%). After the clarification step, a Maillard reaction is initiated as a flavor-enhancing step. By investigating the effects of several operation parameters, including the type of sugar added, sugar dosage, glycine addition, and temperature, on the degree of browning (DB), glucose addition and reaction temperature were found to have significant effects on DB. A synthetic adsorption resin (HP20) was used for the debittering process, which induced a compositional change of the hydrophobic amino acids in the yeast hydrolysate, thereby reducing the bitter taste. The overall dry matter yield and protein yield for the entire process, including the downstream process proposed for the production of brewer's yeast extract were 50 and 50%, respectively.     

A cleavage-based surrogate reporter for the evaluation of CRISPR–Cas9 cleavage efficiency

CRISPR–Cas9 is a powerful tool for genome engineering, but its efficiency largely depends on guide RNA (gRNA). There are multiple methods available to evaluate the efficiency of gRNAs, including the T7E1 assay, surveyor nuclease assay, deep sequencing, and surrogate reporter systems. In the present study, we developed a cleavage-based surrogate that we have named the LacI-reporter to evaluate gRNA cleavage efficiency. The LacI repressor, under the control of the EF-1α promoter, represses luciferase or EGFP reporter expression by binding to the lac operator. Upon CRISPR–Cas9 cleavage at a target site located between the EF-1α promoter and the lacI gene, repressor expression is disrupted, thereby triggering luciferase or EGFP expression. Using this system, we can quantitate gRNA cleavage efficiency by assessing luciferase activity or EGFP expression. We found a strong positive correlation between the cleavage efficiency of gRNAs measured using this reporter and mutation frequency, measured using surveyor and deep sequencing. The genome-editing efficiency of gRNAs was validated in human liver organoids. Our LacI-reporter system provides a useful tool to select efficient gRNAs for genome editing.     

Significant association of the <Emphasis Type="Italic">GABRP</Emphasis> polymorphisms with ulcerative colitis patients

The γ-aminobutyric acid (GABA) is an inhibitory neurotransmitter in the central nervous system. The π subunit receptor of GABA (GABRP) is a transmembrane multi-subunit chloride channel that is expressed in the CNS and several other non-neuronal tissues. The exact function of this gene in non-neuronal tissues is not clearly identified. Our previous customized pilot SNPs chip screens analysis indicated that this gene had strong susceptibility to ulcerative colitis (UC). This study was aimed to validate whether the polymorphisms in the GABRP gene are associated with the susceptibility to UC. The genotype and allele frequencies of the rs929763 rs1063310, rs3805455, rs382819 and rs732157 of the GABRP gene were significantly associated with UC patients. Two haplotype frequencies including a major haplotype of GABRP SNPs were more significantly different between the UC patients and the healthy controls. These results suggest that the polymorphisms in the GABRP gene might be associated with the susceptibility to UC, and the haplotype of GABRP SNPs are useful genetic marker for UC.     

<Emphasis Type="Italic">EPSTI1</Emphasis> polymorphisms are associated with systemic lupus erythematosus

Epithelial stromal interaction 1 (EPSTI1) is an interferon (IFN) response gene, which was originally identified as a stromal fibroblast-induced gene in breast cancer. Our previous study using a customized SNP chip found evidence of an association between EPSTI1 and susceptibility to the chronic inflammatory disease, systematic lupus erythematosus (SLE). This study aimed to validate whether polymorphisms in EPSTI1 are associated with susceptibility to SLE. We analyzed genotype and allele frequencies of SNPs at EPSTI1 using genomic DNA from 119 patients with SLE and 512 healthy controls. We found that the genotype frequencies of rs1044856 and rs1359184 in patients with SLE were significantly different from those found in the control group (P?=?0.03 and P?=?0.01, respectively). In addition, we found that genotype and allele frequencies of rs1359184 in female patients with SLE were significantly different from those found in female controls (P?=?0.02 and P?=?0.04, respectively). We identified two major haplotypes in EPSTI1 that were significantly different between patients with SLE and healthy controls (P?=?0.01 and P?=?0.05, respectively). Furthermore, we found that rs1359184 and rs1044856 in EPSTI1 were associated with antinuclear antibody (ANA) and erythrocyte sedimentation rate (ESR) levels in patients with SLE (P?=?0.0035 and P?=?0.021, respectively). Our findings indicate that polymorphisms in EPSTI1 are associated with susceptibility to SLE and that haplotypes at EPSTI1 may be useful genetic markers for SLE.