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Oxidative stress has been linked to the pathogenesis of diabetic nephropathy, the complication of diabetes in the kidney. NADPH oxidases of the Nox family, and in particular the homologue Nox4, are a major source of reactive oxygen species in the diabetic kidney and are critical mediators of redox signaling in glomerular and tubulointerstitial cells exposed to the diabetic milieu. Here, we present an overview of the current knowledge related to the understanding of the role of Nox enzymes in the processes that control mesangial cell, podocyte and tubulointerstitial cell injury induced by hyperglycemia and other predominant factors enhanced in the diabetic milieu, including the renin-angiotensin system and transforming growth factor-β. The nature of the upstream modulators of Nox enzymes as well as the downstream targets of the Nox NADPH oxidases implicated in the propagation of the redox processes that alter renal biology in diabetes will be highlighted. 相似文献
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Imperfection in the formation of the name Stormbergia dangershoeki Butler is taken as an example so as to warn future taxon authors to repeat it. 相似文献
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Cyclic AMP-independent, dual regulation of voltage-dependent Ca2+ currents by LHRH and somatostatin in a pituitary cell line. 总被引:6,自引:1,他引:5
W Rosenthal J Hescheler K D Hinsch K Spicher W Trautwein G Schultz 《The EMBO journal》1988,7(6):1627-1633
Voltage-dependent Ca2+ currents appear to be involved in the actions of hormones that regulate pituitary secretion. In order to investigate modulation of Ca2+ currents by release-inducing and release-inhibiting hormones, we performed whole-cell clamp experiments in the pituitary cell line GH3. The resting potential was approximately -40 mV; spontaneous action potentials were observed in the majority of cells. Superfusion of cells with the stimulatory hormone, LHRH, depolarized the plasma membrane to approximately -10 mV, whereas the inhibitory hormone, somatostatin, caused hyperpolarization to approximately -60 mV; both hormones suppressed spontaneous action potentials. Under voltage clamp conditions, GH3 cells exhibited slowly and fast inactivating Ca2+ currents. LHRH increased whereas somatostatin decreased the slowly inactivating currents; fast inactivating currents were not affected by these hormones. The stimulatory effect of LHRH was not mimicked by intracellularly applied cAMP. In contrast to vasoactive intestinal peptide and forskolin, LHRH did not activate adenylate cyclase in membranes of GH3 cells, but rather appeared to cause inhibition of the enzyme. Hormonal stimulation and inhibition of inward currents were abolished by pretreatment of the cells with pertussis toxin. In membranes of GH3 cells, we identified a pertussis toxin-sensitive G-protein of the Gi-type and Go. We conclude that LHRH and somatostatin modulate voltage-dependent Ca2+ currents via cAMP-independent mechanisms involving pertussis toxin-sensitive G-proteins. The occurrence of both pertussis toxin-sensitive hormonal stimulation and inhibition of voltage-dependent Ca2+ currents in one cell type suggest that these opposite regulations are mediated by distinct G-proteins. 相似文献
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Immunochemical detection of the alpha-subunit of the G-protein, GZ, in membranes and cytosols of mammalian cells 总被引:1,自引:0,他引:1
K Spicher K D Hinsch H Gausepohl R Frank W Rosenthal G Schultz 《Biochemical and biophysical research communications》1988,157(3):883-890
An antiserum (AS 98) was raised against a synthetic peptide deduced from published cDNA sequences of the alpha-subunit of the putative G-protein, GZ (Fong et al. Proc. Natl. Acad. Sci. USA 85, 3066-3070, 1988; Matsuoka et al. Proc. Natl. Acad. Sci. USA 85, 5384-5388, 1988). In membrane and cytosol preparations of many but not all tested mammalian tissues, AS 98 predominantly recognized two proteins of 40 and 43 kDa Mr. Whereas high levels of a 40 kDa GZ alpha-subunit were found in rat liver membranes and in brain cytosol, AS 98 failed to detect the alpha-subunit of GZ in brain membranes. 相似文献
6.
Microvillar channels: a unique plasma membrane compartment for concentrating lipoproteins on the surface of rat adrenal cortical cells 总被引:3,自引:0,他引:3
Electron microscopic studies of perfused rat adrenals indicate that plasma lipoproteins become concentrated in a specialized cell surface compartment called microvillar channels. Closely associated plasma membranes of sinusoidal microvilli of zona fasciculata cells form channels that normally are filled with electron dense particles the size of high density lipoproteins (HDL). In rats made acutely deficient in plasma lipoproteins (by treatment with 4-aminopyrazolo[3,4-d]pyrimidine (4-APP) for 1 day), particles within the microvillar channels are decreased in number. When adrenal glands of these rats are perfused with media lacking plasma lipoproteins, many but not all of these HDL-like particles are washed out. However, when these adrenals are perfused with large amounts (100-500 micrograms protein/ml) of HDL, microvillar channels become packed with electron dense particles similar to those found in vivo. These microvillar channels become wider and filled with larger particles when low density lipoproteins (LDL) are perfused through the adrenals. Autoradiograms of 125I-labeled HDL-perfused adrenals show silver grains specifically associated with the cell surface microvillar channels, and confirm the notion that the particles filling the channels are exogenously delivered HDL. Physiologic data from similarly perfused adrenals in a parallel study show that the channel-refilling process is directly related to selective (i.e., nonendocytic) cholesterol uptake and that this cholesterol uptake is associated with corticosterone production. Together, these data suggest the hypothesis that plasma lipoprotein cholesterol utilized for corticosteroid synthesis in rat adrenal fasciculata cells may be derived from lipoproteins trapped in surface-associated microvillar channels. Although the mechanism responsible for the cholesterol transfer is not yet defined, it is clearly distinct from the classical process of receptor-mediated endocytosis and catabolism of lipoprotein particles. 相似文献
7.
It is now generally recognized that cell growth conditions in nature are often suboptimal compared to controlled conditions provided in the laboratory. Natural stresses like starvation and acidity are generated by cell growth itself. Other stresses like temperature or osmotic shock, or oxygen, are imposed by the environment. It is now clear that defense mechanisms to withstand different stresses must be present in all organisms. The exploration of stress responses in lactic acid bacteria has just begun. Several stress response genes have been revealed through homologies with known genes in other organisms. While stress response genes appear to be highly conserved, however, their regulation may not be. Thus, search of the regulation of stress response in lactic acid bacteria may reveal new regulatory circuits. The first part of this report addresses the available information on stress response in Lactococcus lactis.Acid stress response may be particularly important in lactic acid bacteria, whose growth and transition to stationary phase is accompanied by the production of lactic acid, which results in acidification of the media, arrest of cell multiplication, and possible cell death. The second part of this report will focus on progress made in acid stress response, particularly in L. lactis and on factors which may affect its regulation. Acid tolerance is presently under study in L. lactis. Our results with strain MG1363 show that it survives a lethal challenge at pH 4.0 if adapted briefly (5 to 15 minutes) at a pH between 4.5 and 6.5. Adaptation requires protein synthesis, indicating that acid conditions induce expression of newly synthesized genes. These results show that L. lactis possesses an inducible response to acid stress in exponential phase.To identify possible regulatory genes involved in acid stress response, we determined low pH conditions in which MG1363 is unable to grow, and selected at 37°C for transposition insertional mutants which were able to survive. About thirty mutants resistant to low pH conditions were characterized. The interrupted genes were identified by sequence homology with known genes. One insertion interrupts ahrC, the putative regulator of arginine metabolism; possibly, increased arginine catabolism in the mutant produces metabolites which increase the pH. Several other mutations putatively map at some step in the pathway of (p)ppGpp synthesis. Our results suggest that the stringent response pathway, which is involved in starvation and stationary phase survival, may also be implicated in acid pH tolerance. 相似文献
8.
Chaubron Franck; Robert Fabien; Gendraud Michel; Petel Gilles 《Plant & cell physiology》1994,35(8):1179-1184
Plasmalemma ATPase from Jerusalem artichoke tubers was studiedin relation to the dormancy of tubers. After partial purification,one peptide of 110 kDa appeared on SDS PAGE electrophoresisfrom dormant and non-dormant materials. ATPase specific activitywas twice higher on dormant material in the crude and solubilizedfractions, but was the same in both materials after partialpurification. Immunolabeling of this enzyme was made using aspecific antibody raised against the C terminal portion of theH+-ATPase from Arabidopsis thaliana. Immunolabeling was morepronounced in dormant material, in vitro and in situ. Severalworks had shown that the C terminal part of the enzyme couldbe involved in its regulation. The results presented are discussedin relation to the hypothesis according to which an internaleffector could modulated the plasmalemma ATPase activity, duringdormancy breaking. (Received October 25, 1993; Accepted September 6, 1994) 相似文献
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