22(R)-hydroxycholesterol and pioglitazone synergistically decrease cholesterol ester via the PPARγ–LXRα–ABCA1 pathway in cholesterosis of the gallbladder

Cholesterosis is a disease of cholesterol metabolism characterized by the presence of excessive lipid droplets in the cytoplasm. These lipid droplets are mainly composed of cholesterol esters derived from free cholesterol. The removal of excess cholesterol from gallbladder epithelial cells (GBECs) is very important for the maintenance of intracellular cholesterol homeostasis and the preservation of gallbladder function. Several lines of evidence have indicated that the activation of either peroxisome proliferator-activated receptor gamma (PPARγ) or liver X receptor α (LXRα) relates to cholesterol efflux. While pioglitazone can regulate the activation of PPARγ, 22(R)-hydroxycholesterol can activate LXRα and is a metabolic intermediate in the biosynthesis of steroid hormones. However, the effect of 22(R)-hydroxycholesterol in combination with pioglitazone on cholesterosis of the gallbladder is unclear. GBECs were treated with pioglitazone, 22(R)-hydroxycholesterol or PPARγ siRNA followed by Western blot analysis for ATP-binding cassette transporter A1 (ABCA1), PPARγ and LXRα. Cholesterol efflux to apoA-I was determined, and Oil Red O staining was performed to monitor variations in lipid levels in treated GBECs. Our data showed that 22(R)-hydroxycholesterol can modestly up-regulate LXRα while simultaneously increasing ABCA1 by 56%. The combination of 22(R)-hydroxycholesterol and pioglitazone resulted in a 3.64-fold increase in ABCA1 expression and a high rate of cholesterol efflux. Oil Red O staining showed an obvious reduction in the lipid droplets associated with cholesterosis in GBECs. In conclusion, the present findings indicate that the anti-lipid deposition action of 22(R)-hydroxycholesterol combined with pioglitazone involves the activation of the PPARγ–LXRα–ABCA1 pathway, increased ABCA1 expression and the efflux of cholesterol from GBECs. Thus, 22(R)-hydroxycholesterol synergistically combined with pioglitazone to produce a remarkable effect on lipid deposition in cholesterosis GBECs.     

Neurotropic and neuroprotective activities of the earthworm peptide Lumbricusin

We recently isolated a polypeptide from the earthworm Lumbricus terrestris that is structurally similar to defensin, a well-known antibacterial peptide. An 11-mer antibacterial peptide (NH₂-RNRRWCIDQQA), designated Lumbricusin, was synthesized based on the amino acid sequence of the isolated polypeptide. Since we previously reported that CopA3, a dung beetle peptide, enhanced neuronal cell proliferation, we here examined whether Lumbricusin exerted neurotropic and/or neuroprotective effects. Lumbricusin treatment induced a time-dependent increase (∼51%) in the proliferation of human neuroblastoma SH-SY5Y cells. Lumbricusin also significantly inhibited the apoptosis and decreased viability induced by treatment with 6-hydroxy dopamine, a Parkinson’s disease-mimicking agent. Immunoblot analyses revealed that Lumbricusin treatment increased ubiquitination of p27^Kip1 protein, a negative regulator of cell-cycle progression, in SH-SY5Y cells, and markedly promoted its degradation. Notably, adenoviral-mediated over-expression of p27^Kip1 significantly blocked the antiapoptotic effect of Lumbricusin in 6-hydroxy dopamine-treated SH-SY5Y cells. These results suggest that promotion of p27^Kip1 degradation may be the main mechanism underlying the neuroprotective and neurotropic effects of Lumbricusin.     

High-Density 3D Single Molecular Analysis Based on Compressed Sensing

Single molecule fitting-based superresolution microscopy achieves sub-diffraction-limit image resolution but suffers from a need for long acquisition times to gather enough molecules. Several methods have recently been developed that analyze high molecule density images but most are only applicable to two dimensions. In this study, we implemented a high-density superresolution localization algorithm based on compressed sensing and a biplane approach that provides three-dimensional information about molecules, achieving super-resolution imaging at higher molecule densities than those achieved using the conventional single molecule fitting method.     

Correlation analysis between three novel SNPs of the Src gene in bovine and milk production traits

As an essential signaling modulator, Src gene appears to be necessary for increased expression of the prolactin receptor, normal downstream signaling, and alveolar cell organization. In this study, we detected the polymorphism of Src gene by polymerase chain reaction-restriction fragment length polymorphism assay (PCR-RFLP) and DNA sequencing methods in 985 individuals from three Chinese cattle breeds. Three novel single nucleotide polymorphisms (SNPs) (g.14062C>T ss161151834, g.17302G>A ss161151835, g.18107T>C ss161151836) were detected. Least squares analysis showed that cows with g.14062C>T-CC genotypes and g.18107T>C-TT genotypes had the highest protein rate, while the cows with g.17302G>A-GG genotype had higher 305 d milk yield (p < 0.05), fat yield (p < 0.01) and protein yield (p < 0.01) than the ones with genotypes g.17302G>A-GA. These results revealed the statistical significant effects of three SNPs of the Src gene on the milk production traits in Chinese Holstein. In addition, based on the nine genotypes constructed from 27 combined haplotypes, the association analysis between combined haplotypes and milk production traits was carried out. Statistic results showed that the cows with combined haplotypes H2H4(CCGATT) had the highest fat rate and the highest protein rate and the cows with combined haplotypes H1H8(TCGATC) and H3H7(TCGGCC) had greater 305 d mild yield than H1H2(CCAATC)(P < 0.05). Our finding demonstrated that the Src gene possibly contributed to conducting association analysis and can be recognized as genetic marker in milk production traits and other performance for animal breeding and genetics.     

Subunit–subunit interactions are weakened in mutant forms of acetohydroxy acid synthase insensitive to valine inhibition

In acetohydroxy acid synthase from Streptomyces cinnamonensis mutants affected in valine regulation, the impact of mutations on interactions between the catalytic and the regulatory subunits was examined using yeast two-hybrid system. Mutations in the catalytic and the regulatory subunits were projected into homology models of the respective proteins. Two changes in the catalytic subunit, E139A (α domain) and ΔQ217 (β domain), both located on the surface of the catalytic subunit dimer, lowered the interaction with the regulatory subunit. Three consecutive changes in the N-terminal part of the regulatory subunit were examined. Changes G16D and V17D in a loop and adjacent α-helix of ACT domain affected the interaction considerably, indicating that this region might be in contact with the catalytic subunit during allosteric regulation. In contrast, the adjacent mutation L18F did not influence the interaction at all. Thus, L18 might participate in valine binding or conformational change transfer within the regulatory subunits. Shortening of the regulatory subunit to 107 residues reduced the interaction essentially, suggesting that the C-terminal part of the regulatory subunit is also important for the catalytic subunit binding.     

Analysis of mitochondrial DNA mutations in D-loop region in thyroid lesions

Background

Mitochondrial defects have been associated with various human conditions including cancers.

Methods

We analyzed the mutations at the mitochondrial DNA (mtDNA) in patients with different thyroid lesions. In particular, in order to investigate if the accumulation of mtDNA mutations play a role in tumor progression, we studied the highly variable main control region of mtDNA, the displacement-loop (D-loop) in patients with non-tumor nodular goiters, with benign thyroid adenomas, and with malignant thyroid carcinomas. Total thyroid tumor or goiter samples were obtained from 101 patients, matched with nearby normal tissue and blood from the same subject.

Results

Noticeably, mitochondrial microsatellite instability (mtMSI) was detected in 2 of 19 nodular goiters (10.53%), and 8 of 77 (10.39%) malignant thyroid carcinomas. In addition, 6 patients, including 5 (6.49%) with malignant thyroid carcinomas and 1 (5.26%) with nodular goiter, were found to harbor point mutations. The majority of the mutations detected were heteroplasmic.

General significance

Our results indicate that mtDNA alterations in the D-loop region could happen before tumorigenesis in thyroid, and they might also accumulate during tumorigenesis.     

Shielding effect of monovalent and divalent cations on solid-phase DNA hybridization: surface plasmon resonance biosensor study

Solid-phase hybridization, i.e. the process of recognition between DNA probes immobilized on a solid surface and complementary targets in a solution is a central process in DNA microarray and biosensor technologies. In this work, we investigate the simultaneous effect of monovalent and divalent cations on the hybridization of fully complementary or partly mismatched DNA targets to DNA probes immobilized on the surface of a surface plasmon resonance sensor. Our results demonstrate that the hybridization process is substantially influenced by the cation shielding effect and that this effect differs substantially for solid-phase hybridization, due to the high surface density of negatively charged probes, and hybridization in a solution. In our study divalent magnesium is found to be much more efficient in duplex stabilization than monovalent sodium (15 mM Mg²⁺ in buffer led to significantly higher hybridization than even 1 M Na⁺). This trend is opposite to that established for oligonucleotides in a solution. It is also shown that solid-phase duplex destabilization substantially increases with the length of the involved oligonucleotides. Moreover, it is demonstrated that the use of a buffer with the appropriate cation composition can improve the discrimination of complementary and point mismatched DNA targets.     

Multilocus sequence typing and virulence factors analysis of Escherichia coli O157 strains in China

Escherichia coli O157:H7, an important food-borne pathogen, has become a major public health concern worldwide. The aim of this study was to investigate the molecular epidemiologic feature of E. coli O157:H7 strains in China. 105 E. coli O157:H7 isolates were collected from various hosts and places over 9 years. A multilocus sequence typing scheme (MLST) was applied for bacteria genotyping and polymerase chain reaction (PCR) was used for virulence factor identification. Seven new MLST sequence types (STs), namely ST836, ST837, ST838, ST839, ST840, ST841, and ST842 were identified, which grouped into two lineages. Phylogenetic analysis suggested that the most two frequent STs in China, ST837 and ST836, may be the derivatives of E. coli O157:H7 Sakai or E. coli O157:H7 EDL933. Geographical diversity and host variety of E. coli O157:H7 were observed in China. In addition, the different distribution of tccp was detected. The data presented herein provide new insights into the molecular epidemiologic feature of E. coli O157:H7, and aid in the investigation of the transmission regularity and evolutionary mechanism of E. coli O157:H7.