BASP1 promotes high glucose-induced endothelial apoptosis in diabetes via activation of EGFR signaling.

AIMS: Diabetes mellitus is a common chronic disease of glucose metabolism. Endothelial dysfunction is an early event in diabetes complicated by cardiovascular disease. This study aimed to reveal the expression of BASP1 and its biological roles in endothelial cell dysfunction in diabetes complicated by cardiovascular disease. MATERIALS AND METHODS: By analyzing the databases related to diabetes complicated with coronary heart disease, BASP1 was screened out as an upregulated gene. Human umbilical vein endothelial cells (HUVECs) and primary mouse aortic endothelial cells were treated with high glucose to establish cell models of diabetes-related endothelial dysfunction, and the expression changes of BASP1 were verified by RT-qPCR, western blot, and immunofluorescence. BASP1 was silenced or overexpressed by siRNA or overexpression plasmid, and its effects on cell migration, apoptosis, tube formation, inflammatory response, and ROS were detected. The possible signaling pathway of BASP1 was found and the mechanism of BASP1 on promoting the progression of endothelial dysfunction was explored using the EGFR inhibitor, gefitinib. RESULTS: Bioinformatics analysis indicated that the expression of BASP1 in patients with diabetes mellitus and concomitant coronary heart disease was increased. High glucose induced the upregulation of BASP1 expression in endothelial cells, and showed a time-dependent relationship. Silencing of BASP1 alleviated the damage of high glucose to endothelial cells. BASP1 regulated EGFR positively. The promoting effect of BASP1 on endothelial cell apoptosis may be achieved by regulating the EGFR pathway. CONCLUSION: BASP1 promotes endothelial cell injury induced by high glucose in patients with diabetes, which may be activated by activating the EGFR pathway.

TMEM120A contains a specific coenzyme A-binding site and might not mediate poking- or stretch-induced channel activities in cells.

TMEM120A, a member of the transmembrane protein 120 (TMEM120) family, has a pivotal function in adipocyte differentiation and metabolism, and may also contribute to sensing mechanical pain by functioning as an ion channel named TACAN. Here we report that expression of TMEM120A is not sufficient in mediating poking- or stretch-induced currents in cells and have solved cryo-electron microscopy (cryo-EM) structures of human TMEM120A (HsTMEM120A) in complex with an endogenous metabolic cofactor (coenzyme A, CoASH) and in the apo form. HsTMEM120A forms a symmetrical homodimer with each monomer containing an amino-terminal coiled-coil motif followed by a transmembrane domain with six membrane-spanning helices. Within the transmembrane domain, a CoASH molecule is hosted in a deep cavity and forms specific interactions with nearby amino acid residues. Mutation of a central tryptophan residue involved in binding CoASH dramatically reduced the binding affinity of HsTMEM120A with CoASH. HsTMEM120A exhibits distinct conformations at the states with or without CoASH bound. Our results suggest that TMEM120A may have alternative functional roles potentially involved in CoASH transport, sensing, or metabolism.

Phospholipid translocation captured in a bifunctional membrane protein MprF.

As a large family of membrane proteins crucial for bacterial physiology and virulence, the Multiple Peptide Resistance Factors (MprFs) utilize two separate domains to synthesize and translocate aminoacyl phospholipids to the outer leaflets of bacterial membranes. The function of MprFs enables Staphylococcus aureus and other pathogenic bacteria to acquire resistance to daptomycin and cationic antimicrobial peptides. Here we present cryo-electron microscopy structures of MprF homodimer from Rhizobium tropici (RtMprF) at two different states in complex with lysyl-phosphatidylglycerol (LysPG). RtMprF contains a membrane-embedded lipid-flippase domain with two deep cavities opening toward the inner and outer leaflets of the membrane respectively. Intriguingly, a hook-shaped LysPG molecule is trapped inside the inner cavity with its head group bent toward the outer cavity which hosts a second phospholipid-binding site. Moreover, RtMprF exhibits multiple conformational states with the synthase domain adopting distinct positions relative to the flippase domain. Our results provide a detailed framework for understanding the mechanisms of MprF-mediated modification and translocation of phospholipids.

Structural insight into light harvesting for photosystem II in green algae.

Green algae and plants rely on light-harvesting complex II (LHCII) to collect photon energy for oxygenic photosynthesis. In Chlamydomonas reinhardtii, LHCII molecules associate with photosystem II (PSII) to form various supercomplexes, including the C2S2M2L2 type, which is the largest PSII-LHCII supercomplex in algae and plants that is presently known. Here, we report high-resolution cryo-electron microscopy (cryo-EM) maps and structural models of the C2S2M2L2 and C2S2 supercomplexes from C. reinhardtii. The C2S2 supercomplex contains an LhcbM1-LhcbM2/7-LhcbM3 heterotrimer in the strongly associated LHCII, and the LhcbM1 subunit assembles with CP43 through two interfacial galactolipid molecules. The loosely and moderately associated LHCII trimers interact closely with the minor antenna complex CP29 to form an intricate subcomplex bound to CP47 in the C2S2M2L2 supercomplex. A notable direct pathway is established for energy transfer from the loosely associated LHCII to the PSII reaction centre, as well as several indirect routes. Structure-based computational analysis on the excitation energy transfer within the two supercomplexes provides detailed mechanistic insights into the light-harvesting process in green algae.

Enhancement of alpha- and beta-galactosidase activity in Lactobacillus reuteri by different metal ions.

The hydrolysis of oligosaccharides and lactose is of great importance to the food industry. Normally, oligosaccharides like raffinose, stachyose, and verbascose which are rich in different plants like soy bean are considered indigestible by the human gut. Moreover, many humans suffer from lactose intolerance due to the absence of effective enzyme that can digest lactose. alpha-Galactosidase can digest oligosaccharides like raffinose, while beta-galactosidases can hydrolyze lactose. Therefore, selection of microorganisms safe for human use and capable of producing high levels of enzymes becomes an attractive task. The objective of this study was to investigate the enhancement of alpha- and beta-galactosidase activity in Lactobacillus reuteri by different metal ions. Ten millimolar of Na(+), K(+), Fe(2+), and Mg(2+) and 1 mM of Mn(2+) were added separately to the growth culture of six strains of L. reuteri (CF2-7F, DSM20016, MF14-C, MM2-3, MM7, and SD2112). Results showed that L. reuteri CF2-7F had the highest alpha- and beta-galactosidase activity when grown in the medium with added Mn(2+) ions (22.7 and 19.3 Gal U/ml, respectively). 0.0274% of Mn(2+) ions lead to 27, 18% enhancement of alpha- and beta-galactosidase activity over the control group, and therefore, it could be added to the growth culture of CF2-7F to produce enhanced levels of alpha- and beta-galactosidase activity. The addition of Fe(2+) led to a significant (P < 0.01) decrease in the activity of both enzymes for most strains. This study shows that modified culture medium with that 0.0274% Mn(2+) can be used to promote the production for alpha- and beta-galactosidase in L. reuteri CF2-7F, which may lead to enhancement of alpha- and beta-galactosidase activity and have a good potential to be used in the food industry.

Alternative method for site-directed mutagenesis of complex polyketide synthase in Streptomyces albus JA3453.

Sequence analysis of oxazolomycin (OZM) biosynthetic gene cluster from Streptomyces albus JA3453 revealed a gene, ozmH, encoding a hybrid polyketide and non-ribosomal peptide enzyme. Tandem ketosynthase (KS) domains (KS 10-1 and KS 10-2) were characterized and they show significant homology with known KSs. Using an alternative method that involves RecA-mediated homologous recombination, the negative selection marker sacB gene, and temperature-sensitive replications, site-directed mutagenesis of the catalytic triad amino acid cysteines were carried out in each of the tandem KS domains to test the function they play in OZM biosynthesis. HPLC-mass spectrometry analysis of the resulting mutant strains showed that KS 10-2 is essential for OZM biosynthesis but KS 10-1 is not indispensable and might serve as a "redundant" domain. These results confirmed the existence of an "extra domain" in complex polyketide synthase.

Utilization of the methoxymalonyl-acyl carrier protein biosynthesis locus for cloning the oxazolomycin biosynthetic gene cluster from Streptomyces albus JA3453.

Oxazolomycin (OZM), a hybrid peptide-polyketide antibiotic, exhibits potent antitumor and antiviral activities. Using degenerate primers to clone genes encoding methoxymalonyl-acyl carrier protein (ACP) biosynthesis as probes, a 135-kb DNA region from Streptomyces albus JA3453 was cloned and found to cover the entire OZM biosynthetic gene cluster. The involvement of the cloned genes in OZM biosynthesis was confirmed by deletion of a 12-kb DNA fragment containing six genes for methoxymalonyl-ACP biosynthesis from the specific region of the chromosome, as well as deletion of the ozmC gene within this region, to generate OZM-nonproducing mutants.

Enzymatic degradation of oligosaccharides in pinto bean flour.

The use of dry edible beans is limited due to the presence of flatulence factors, the raffinose oligosaccharides. Our objective was to investigate the process for the removal of oligosaccharides from pinto bean using enzymatic treatment and to compare it to removal by soaking and cooking methods. Crude enzyme preparation was produced by six fungal species on wheat bran- and okara-based substrates with soy tofu whey. The loss of raffinose oligosaccharides after soaking pinto beans for 16 h at the room temperature was 10%, after cooking for 90 min was 52%, and after autoclaving for 30 min was 58%. On the other hand, the treatment using crude alpha-galactosidase (60 U mL(-1)) produced by Aspergillus awamori NRRL 4869 from wheat bran-based substrate with soy tofu whey on pinto bean flour for 2 h completely hydrolyzed raffinose oligosaccharides. These results supported that the enzymatic treatment was the most effective among various processing methods tested for removing the raffinose oligosaccharides, and hence, crude alpha-galactosidases from fungi have potential use in the food industry.

[Effect of apoptosis in human breast cancer cells and its probable mechanisms by genistein].

OBJECTIVE: To investigate the effects of genistein on human breast cancer cell MCF-7 apoptosis and its probable mechanisms. METHODS: In this study, the methods of MTT, cell apoptosis detecting in fluorescent and electronic microscope and flow cytometry, and expression of Bax and erbB-2 protein were employed. RESULTS: The results showed that genistein could significantly inhibit the growth and induce the apoptosis of MCF-7 cells. Apoptotic cells of morphology from MCF-7 cells treated by different concentrations of genistein were observed by fluorescent and electronic microscope and the frequency of apoptosis in MCF-7 cells by flow cytometry showed increasingly with concentrations of genistein increased. The expression of Bax protein in MCF-7 cells was increased and the expression of erbB-2 protein was decreased with the doses of genistein. CONCLUSION: Genistein can induce MCF-7 cells apoptosis and it may be one of the mechanisms for the inhibitory effect of genistein in human cancer cells.

Blocking effects of genistein on cell proliferation and possible mechanism in human gastric carcinoma.

AIM: To study the blocking effects of genistein on cell proliferation cycle in human gastric carcinoma cells (SGC-7901) and the possible mechanism. METHODS: MTT assay was applied in the detection of the inhibitory effects of genistein on cell proliferation. Flow cytometry was used to analyze the cell cycle distribution. Immunocytochemical technique and Western blotting were performed to detect the protein expression of cyclin D1, cyclin B1 and p21(waf1/cip1). RESULTS: Genistein significantly inhibited the growth and proliferation of human gastric carcinoma cells (SGC-7901). Seven days after treatment with different concentrations of genistein (2.5, 5.0, 10.0, 20.0 microg/mL), the growth inhibitory rates were 11.2%, 28.8%, 55.3%, 84.7% respectively and cell cycles were arrested at the G(2)/ M phase. Genistein decreased cyclin D1 protein expression and enhanced cyclin B1 and p21(waf/cip1) protein expression in a concentration-dependent manner. CONCLUSION: The growth and proliferation of SGC-7901 cells can be inhibited by genistein via blocking the cell cycle, with reduced expression of cyclin D1 and enhanced expression of cyclin B1 and p21(waf/cip1) protein in the concentration range of 0-20 microg/mL.

[Study of the effects of isoflavone on serum lipid and bone biochemical markers in ovariectomized rats].

The effects of isoflavone on serum lipid and bone biochemical markers in ovariectomized rats were studied. Four-month old Wistar rats were divided into 6 groups according to their weights. Rats were either sham-operated or ovariectomized (ovx). Some ovx rats were given different dosage of isoflavone or estrostilben. Sixteen weeks later, the rats were killed and the serum were separated to determine the analytical indexes. The experiment results show that in the group of isoflavone the content of serum HDL and bone formation index bone gamma-carkoxyglutamate protein (BGP) increase, but total cholesterol (TC), triglycerides (TG) and bone absorption index tartrate-resistant acid phosphatase (TRAP) decrease obviously. The results from this study indicate that isoflavone can modulate serum lipid and inhibit bone absorption.

[Study on mechanisms of human gastric carcinoma cells apoptosis induced by genistein].

In order to study the apoptosic effect of genistein on human gastric carcinoma SGC-7901 cells, DAPI dyeing and DNA electrophoresis were used. Western Blot was used to detect the changes of the expression of p53 protein, Caspase-3 after SGC-7901 cells were exposed to genistein. The results showed that genistein induced cell apoptosis. Genistein also decreased the expression of mutant p53, and increased the protein expression of Caspase-3. These indicated that genistein could induce the apoptosis of gastric carcinoma cells. The inhibition of the expression of mutant p53 and enhance of the protein expression of Caspase-3 would be possible mechanism.

[Effect of isoflavone on human breast cancer cell line MCF-7 and its probable mechanism].

The effects of isoflavone on human breast cancer cell line MCF-7 growth and apoptosis and its probable mechanisms were studied in vitro. The results showed that isoflavone could significantly inhibit the growth and induce the apoptosis of MCF-7 cells. Western Blotting showed that isoflavone increased iNOS protein expression. These results suggested that isoflavone significantly inhibited the MCF-7 growth and induced cell apoptosis by regulating iNOS gene expression.

[Inhibitory effects of genistein on the synthesis of DNA and the protein expression of cyclin D1 in human gastric carcinoma cell-line].

In order to study the inhibitory effects of genistein on the growth of human gastric carcinoma cells and to explore its possible mechanism, cell proliferation and DNA incorporation tests are applied. Immunocytochemistry is also applied in this study to detect the protein expression of cyclin D1 after the cell-line is exposed to genistein. The results showed that the growth of the cells and the synthesis of DNA is decreased in a marked dose-dependent manner after the treatment with genistein. Genistein also decreased the protein expression of cyclin D1. The above mentioned results indicate that genistein inhibits the growth of gastric carcinoma cells and the possible mechanism of this inhibition might be resulted from inhibiting the synthesis of DNA and the protein expression of cyclin D1.