[Advances of the technologies in large-scale membrane proteome identification].

Membrane proteins play important functions not only as receptors and transporters, but also in many other important intracellular functions such as photosynthetic and respiratory electron transport. Identification of membrane proteins is a necessary step to understand their functions. Membrane proteins are generally highly hydrophobic and difficult to be resolved by aqueous solutions, and large-scale proteomic identification of membrane proteins has been a great technical challenge. Significant efforts have been invested in the field to improve the solubility of membrane proteins in aqueous solutions that are compatible for mass spectrometry analysis. This review summarizes the main technological achievements in the field of membrane proteomics particularly for the improvement of membrane protein identification, and uses the photosynthetic model cyanobacterium Synechocystis sp. PCC6803 as an example to illustrate how technology advances push forward the field in terms of the increased coverage of membrane proteome identification.

Effects of hot air drying process on lipid quality of whelks Neptunea arthritica cumingi Crosse and Neverita didyma.

Whelks Neptunea arthritica cumingi Crosse and Neverita didyma were processed by hot air drying and changes of thei lipids and the mechanism involved were evaluated by analyzing peroxide value, thiobarbituric acid-reactive substances, total oxidation value, fatty acid composition, activities of lipases and lipoxygenase (LOX), as well as contents of triacylglycerol (TAG), free fatty acid (FFA), phosphatidylcholine (PC) and phosphatidylethanolamine (PE). The processing significantly decreased the contents of PC, PE and TAG but increased the content of FFA. The presence of acid lipase and phospholipase in whelk tissues and their activity preservation during processing suggest that the enzymes may help hydrolyze lipids. By contrast, the reduction of PC, PE and TAG was more pronounced than the increase in FFA in whelk tissues upon processing, indicating the oxidative degradation of FFA. LOX may play a role in lipid oxidation due to the stability of the starting components during processing.

Autophagy plays beneficial effect on diabetic encephalopathy in type 2 diabetes: studies in vivo and in vitro.

OBJECTIVES: The hypothalamus regulates metabolism and feeding behavior by perceiving the levels of peripheral insulin. However, little is known about the hypothalamic changes after aberrant metabolism. In this study, we investigated the changes of insulin and autophagy relevant signals of hypothalamus under diabetes mellitus. METHODS: C57B/L mice were injected with low-dose streptozotocin (STZ) and fed with high-fat diet to induce type 2 diabetes mellitus. In vitro, PC12 cells were treated with oleic acid to mimic lipotoxicity. RESULTS: Results showed that the cholesterol level in the hypothalamus of the diabetic mice was higher than that of the normal mice. The expression of insulin receptors and insulin receptor substrate-1 were downregulated and the number of Fluoro-Jade C positive cells significantly increased in the hypothalamic arcuate nucleus of the diabetic mice. Furthermore, Upregulation of mammalian target of rapamycin (mTOR) and downregulation of LC 3II were obvious in the hypothalamus of the diabetic mice. In vitro, results showed that high-lipid caused PC12 cell damage and upregulated LC3 II expression. Pretreatment of cells with 3-methyladenine evidently downregulated LC3 II expression and aggravated PC12 cell death under high lipid conditions. By contrast, pretreatment of cells with rapamycin upregulated LC3 II expression and ameliorated PC12 cell death caused by lipotoxicity. CONCLUSION: These results demonstrate that autophagy activation confers protection to neurons under aberrant metabolism and that autophagy dysfunction in the hypothalamus occurs in the chronic metabolic disorder such as T2DM.

The effect of Platycodin D on the expression of cytoadherence proteins P1 and P30 in Mycoplasma pneumoniae models.

Platycodin D is one of the most important monomers of the Qinbaiqingfei pellet (Qinbai), which has already been approved as the first effective new Traditional Chinese Medicine used to fight against Mycoplasma pneumoniae (M. pneumoniae) in clinic in China. In previous studies, pharmacodynamics experiment has proved that Platycodin D has anti-M. pneumoniae effect and the minimum inhibitory concentration (MIC) is 16mµg/ml. This paper further clarified that the mechanism underlying the anti-M. pneumoniae effect of Platycodin D might be due to M. pneumoniae adhesion proteins P1 and P30. P1 and P30 expression levels in M. pneumoniae strain, M. pneumoniae-infected BALB/c mice, and M. pneumoniae-infected A549 cells were determined by reverse transcription PCR. Platycodin D strongly inhibited P1 and P30 expression in M. pneumonia and high dosage of Platycodin D exhibited a greater effect on reducing P1 and P30 expression than low dose Platycodin D. Platycodin D prevented M. pneumoniae infection through inhibiting the expression of adhesion proteins, which might be one of the mechanisms for the anti-M. pneumoniae properties of Qinbai. These results provide a foundation to further explore the mechanisms of action of Qinbai in future studies.

[Microwave extraction of total flavonoids in peanut skins].

OBJECTIVE: To determine the optimum microwave extraction process of flavonoids in peanut skin. METHODS: The effects of extraction methods, microwave irradiation time, microwave power, ethanol concentration, material-liquid ratio and extraction times on the extraction of total flavonoids in peanut skin was investigated. RESULTS: Based on the single factor experiments, the extraction conditions were optimized by orthogonal experiment. Microwave extraction method had higher extraction rate, and was selected for the extraction of total flavonoids in peanut skin. The optimum extraction conditions were as follows: the microwave power was 690 W, the extraction time was 40 s, the concentration of ethanol was 55%, the material-liquid ratio was 1: 20. Under the optimum conditions, the yield of total flavonoids was 3.18%. CONCLUSION: The microwave extraction method is simple, and can be applied to the fast extraction of total flavonoids in peanut skin.

pVHL mediates K63-linked ubiquitination of nCLU.

pVHL, product of von Hippel-Lindau (VHL) tumor suppressor gene, functions as the substrate recognition component of an E3-ubiquitin ligase that targets proteins for ubiquitination and proteasomal degradation. Hypoxia-inducible factor α (HIFα) is the well-known substrate of pVHL. Besides HIFα, pVHL also binds to many other proteins and has multiple functions. In this manuscript, we report that the nuclear clusterin (nCLU) is a target of pVHL. We found that pVHL had a direct interaction with nCLU. nCLU bound to pVHL at pVHL's ß domain, the site for recognition of substrate, indicating that nCLU might be a substrate of pVHL. Interestingly, pVHL bound to nCLU but did not lead to nCLU destruction. Further studies indicated that pVHL mediated K63-linked ubiquitination of nCLU and promoted nCLU nuclear translocation. In summary, our results disclose a novel function of pVHL that mediates K63-linked ubiquitination and identify nCLU as a new target of pVHL.

Prolyl hydroxylase domain protein 3 targets Pax2 for destruction.

Prolyl hydroxylase domain proteins (PHDs) hydroxylate HIFα in the presence of oxygen, leading to HIFα proteasomal destruction. The PHDs family comprises PHD1, 2, and 3. Recent studies indicate that, in addition to HIFα, PHDs have other substrates. Paired box (Pax) 2, a transcription factor, was found aberrantly expressed in a variety of cancers. However, the underlying mechanisms remain unknown. Here we demonstrate that PHD3 is a negative regulator of expression of Pax2. We found that PHD3 bound to Pax2 and mediated Pax2 destruction directly. Inhibition of PHD3 hydroxylase activity led to upregulation of Pax2 protein but not mRNA level. We found that Pax2 protein was increased and PHD3 protein was decreased in colorectal cancer, and the increased Pax2 was associated with decreased PHD3. Our results suggest that PHD3 targets Pax2 for destruction. The findings may disclose a mechanism for the regulation of Pax2 expression in cancer cells.

Discrepancy of biologic behavior influenced by bone marrow derived cells in lung cancer.

Disseminated cancer cells may initially require local nutrients and growth factors to thrive and survive in bone marrow. However, data on the influence of bone marrow derived cells (BMDC, also called bone stromal cells in some publications) on lung cancer cells is largely unexplored. This study explored the mechanism of how bone stromal factors contribute to the bone tropism in lung cancer. The difference among lung cancer cell lines in their abilities to metastasize to bone was found using the SCID animal model. Supernatant of bone marrow aspiration (BM) and condition medium from human bone stromal cells (BSC) were used to study the activity of bone stromal factors. We found bone stromal factors significantly increased the proliferation, invasion, adhesion and expression of angiogenosis-related factors, and inhibited the apoptosis for high bone metastasis H460 lung cancer cells. These biologic effects were not seen in SPC-A1 or A549 cells, which are low bone metastasis lung cancer cells. Adhesion of H460 cells to surface coated with bone stromal cells can activate some signal transduction pathways, and alter the expression of adhesion associated factors, including integrin ß 3 and ADAMTS-1, two potential targets related with bone metastasis. We concluded that bone marrow derived cells had a profound effect on biological behavior of lung cancers, therefore favoring the growth of lung cancer cells in bone.

Benzo[a]pyrene induces expression of matrix metalloproteinases and cell migration and invasion of vascular smooth muscle cells.

Benzo[a]pyrene (B[a]P) has been shown to accelerate atherosclerosis development in animal models. However, the mechanisms that B[a]P induces atherogenesis are unclear. Abnormal migration and invasion of vascular smooth muscle cells (VSMCs) is a major contributor to the development of atherosclerotic lesions. In this article, we demonstrated that B[a]P promoted the migration and invasion of rat VSMCs. B[a]P increased the mRNA levels of matrix metalloproteinase (MMP) 1, 2, 3, and 9. The MMPs inhibitor GM6001 inhibited B[a]P-induced invasion of VSMCs. Among the MMPs mentioned above, MMP-3 had the maximal induction. Mechanistic studies indicate that B[a]P-induced transcriptional activation of MMP-3 is not mediated by AP-1, NF-kappaB. B[a]P-induced expression of MMPs was attenuated by alpha-naphthoflavone, the aryl hydrocarbon receptor antagonist. In addition, alpha-naphthoflavone inhibited B[a]P-induced migration and invasion of VSMCs. These results suggest that the aryl hydrocarbon receptor plays an important role in B[a]P-induced expression of MMPs and migration and invasion of VSMC. Our findings may reveal a novel role of B[a]P in inducing atherogenesis.

Insulin-like growth factor-I induces reactive oxygen species production and cell migration through Nox4 and Rac1 in vascular smooth muscle cells.

AIMS: We showed previously that insulin-like growth factor-I (IGF-I)-induced vascular smooth muscle cells (VSMCs) proliferation through the production of reactive oxygen species (ROS). However, how IGF-I-induced ROS was unknown. The aim of this study is to investigate the mechanisms by which IGF-I induces ROS production in VSMCs. Methods results Reverse transcription-PCR, real-time PCR, immunoblotting, and confocal microscopic image analysis were employed to determine protein expression, small Rho-GTPase Rac1 activation, and ROS production. Inhibition of NADPH oxidase 4 (Nox4) or Rac1 was performed by means of siRNA technology. Inhibition of Rac1 activity was accomplished using dominant-negative form of Rac1 (N17Rac1) plasmid. VSMCs from Sprague-Dawley rat thoracic aortas were used in this work.IGF-I enhanced ROS production in rat VSMCs. IGF-I increased the protein level of Nox4 but had little effect on its mRNA level. IGF-I induced the activation of Rac1. Either knockdown of Nox4 or inactivation of Rac1 impaired IGF-I-induced ROS. Over-expression of Nox4 increased NADPH oxidase activity, which was not influenced by inactivation of Rac1. Neither over-expression nor knockdown of Rac1 influenced Nox4 expression. Knockdown of Nox4 did not affect IGF-I-induced activation of Rac1. IGF-I increased matrix metalloproteinase (MMP)-2 and 9 activity and promoted VSMC migration, which was inhibited by knockdown of Nox4 and inactivation of Rac1. CONCLUSION: Our results suggest that Nox4 and Rac1 mediate IGF-I-induced ROS production and cell migration in VSMCs and that Nox4 is not regulated by Rac1.