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Cardiovasc Res. 2012 May 11; Mitochondrial activity is critical for efficient function of the cardiovascular system. In response to cardiovascular injury, mitochondrial dysfunction occurs and can lead to apoptosis and necrosis. Calpains are a 15 member family of Ca(2+)-activated cysteine proteases localized to the cytosol and mitochondria, and several have been shown to regulate apoptosis and necrosis. For example, in endothelial cells Ca(2+)-overload causes mitochondrial calpain 1 cleavage of the Na(+)/Ca(2+) exchanger leading to mitochondrial Ca(2+) accumulation. Also, activated calpain 1 cleaves Bid, inducing cytochrome c release and apoptosis. In renal cells, calpains 1 and 2 promote apoptosis and necrosis by cleaving cytoskeletal proteins, which increases plasma membrane permeability, and cleavage of caspases. Calpain 10 cleaves electron transport chain proteins, causing decreased mitochondrial respiration and excessive activation or inhibition of calpain 10 activity induces mitochondrial dysfunction and apoptosis. In cardiomyocytes, calpain 1 activates caspase 3 and poly ADP ribose polymerase during tumor necrosis factor-α-induced apoptosis and calpain 1 cleaves apoptosis inducing factor after Ca(2+) overload. Many of these observations have been elucidated with calpain inhibitors, but most calpain inhibitors are not specific for calpains or a specific calpain family member, creating more questions. The following review will discuss how calpains affect mitochondrial function and apoptosis within the cardiovascular system. See the original post here:
Open Biochem J. 2012; 6: 40-2 A new hypothesis is discussed, which describes the initiation of the carcinogenesis through polycyclic aromatic hydrocarbons (PAHs) and aminoazo dyes (AZOs) as a two-step process: the oncogenic proteins of the ras or ras-like on-cogenes activated by mutation (“initiation A “) co-operate with the complexes in the plasma membrane formed during the “initiation B ” stage from the parent compounds of the PAHs or AZOs with cholesterol and apolipoprotein A-I. The final result of this co-operation, or the “complete initiation”, is an irreversibly modified membrane architecture with negative consequences for growth control. Go here to read the rest:
J Biol Chem. 2012 May 10; Post-translational modifications of proteins are important for the regulation of cell fate and functions; one of these post-translational modifications is arginylation. We have previously established that calreticulin (CRT), an endoplasmic reticulum (ER) resident, is also one of the arginylated substrates found in the cytoplasm. In the present study, we describe that arginylated CRT (R-CRT) binds to the cell membrane and identified its role as a pre-apoptotic signal. We also show that cells lacking arginyl-tRNA protein transferase (ATE1-/- cells) are less susceptible to apoptosis than WT cells. Under these conditions R-CRT is present on the cell membrane, but at early stages is differently localized in stress granules (SGs). Moreover, cells induced to undergo apoptosis by arsenite show increased R-CRT on their cell surface. Exogenously applied R-CRT binds to the cell membrane and is able both to increase the number of cells undergoing apoptosis in WT cells and overcome apoptosis resistance in ATE1-/- cells that express R-CRT on the cell surface. Thus, these results demonstrate the importance of surface R-CRT in the apoptotic response of cells, implying that post-translational arginylation of CRT can regulate its intracellular localization, cell function and survival. Read the original:
Ann Dermatol. 2012 May; 24(2): 168-74 Aquaporins (AQPs) are a family of water transporting proteins present in many mammalian epithelial and endothelial cell types. Among the AQPs, AQP3 is known to be a water/glycerol transporter expressed in human skin.The relationship between the expression level of AQP3 and transpidermal water loss (TEWL) in the lesional and peri-lesional skin of psoriasis-affected patients, and skin hydration in the lesional and peri-lesional skin of psoriasis patients, was investigated.The expression of AQP3 in psoriasis-affected and healthy control skin was determined using immunohistochemical and immunofluroscence staining. TEWL and skin hydration were measured using a Tewameter® TM210 (Courage & Khazaka, Cologne, Germany) and a Corneometer® CM 820 (Courage & Khazaka), respectively.AQP3 was mainly expressed in the plasma membrane of stratum corneum and the stratum spinosum in normal epidermis. Unlike the normal epidermis, AQP3 showed decreased expression in the lesional and peri-lesional epidermis of psoriasis. TEWL was increased, and skin hydration was decreased, in the lesional and peri-lesional skin of psoriasis patients, compared with the healthy control sample.Although various factors contribute to reduced skin hydration in the lesional and peri-lesional skin of psoriasis, AQP3 appears to be a key factor in the skin dehydration of psoriasis-affected skin.
Methods Mol Biol. 2012; 876: 67-82 The plasma membrane (PM) controls cell's exchange of both material and information with the outside environment, and PM-associated proteins play key roles in cellular regulation. Numerous cell surface receptors allow cells to perceive and respond to various signals from neighbor cells, pathogens, or the environment; large numbers of transporter and channel proteins control material uptake or release. Quantitative proteomic analysis of PM-associated proteins can identify key proteins involved in signal transduction and cellular regulation. Here, we describe a protocol for quantitative proteomic analysis of PM proteins using two-dimensional difference gel electrophoresis. The protocol has been successfully employed to identify new components of the brassinosteroid signaling pathway, and should also be applicable to the studies of other plant signal transduction pathways and regulatory mechanisms. See the original post:
Methods Mol Biol. 2012; 876: 67-82 The plasma membrane (PM) controls cell's exchange of both material and information with the outside environment, and PM-associated proteins play key roles in cellular regulation. Numerous cell surface receptors allow cells to perceive and respond to various signals from neighbor cells, pathogens, or the environment; large numbers of transporter and channel proteins control material uptake or release. Quantitative proteomic analysis of PM-associated proteins can identify key proteins involved in signal transduction and cellular regulation. Here, we describe a protocol for quantitative proteomic analysis of PM proteins using two-dimensional difference gel electrophoresis. The protocol has been successfully employed to identify new components of the brassinosteroid signaling pathway, and should also be applicable to the studies of other plant signal transduction pathways and regulatory mechanisms. Excerpt from:
Neoplasia. 2012 Apr; 14(4): 311-23 Statins, HMG-CoA reductase inhibitors, are used in the prevention and treatment of cardiovascular diseases owing to their lipid-lowering effects. Previous studies revealed that, by modulating membrane cholesterol content, statins could induce conformational changes in cluster of differentiation 20 (CD20) tetraspanin. The aim of the presented study was to investigate the influence of statins on glucose transporter 1 (GLUT1)-mediated glucose uptake in tumor cells. We observed a significant concentration- and time-dependent decrease in glucose analogs' uptake in several tumor cell lines incubated with statins. This effect was reversible with restitution of cholesterol synthesis pathway with mevalonic acid as well as with supplementation of plasma membrane with exogenous cholesterol. Statins did not change overall GLUT1 expression at neither transcriptional nor protein levels. An exploratory clinical trial revealed that statin treatment decreased glucose uptake in peripheral blood leukocytes and lowered (18)F-fluorodeoxyglucose ((18)F-FDG) uptake by tumor masses in a mantle cell lymphoma patient. A bioinformatics analysis was used to predict the structure of human GLUT1 and to identify putative cholesterol-binding motifs in its juxtamembrane fragment. Altogether, the influence of statins on glucose uptake seems to be of clinical significance. By inhibiting (18)F-FDG uptake, statins can negatively affect the sensitivity of positron emission tomography, a diagnostic procedure frequently used in oncology. The rest is here: |
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