Structural changes of DNA induced by mono- and binuclear cancer drugs

The structural features of the drug-DNA adducts resulted from treatment of DNA with the platinum based mononuclear drug cisplatin and the binuclear drug [{trans-PtCl(NH3)2}2H2N(CH2)4NH2]Cl2 or bis(platin) have been investigated by atomic force microscopy (AFM). Reduction in the contour length of the DNA fragments has been observed after cisplatin treatment while, compaction and aggregation are found to be the primary structural modifications following treatment with the binuclear drug. The intermolecular interaction upon bis(platin) treatment leads to observation of highly condense aggregates without a distinct sight of single isolated DNA molecule. These differences in drug binding indicate that unlike the mononuclear drug cisplatin, bis(platin) causes extensive interhelical/intermolecular cross-linking through its multiple linking sites. To our knowledge, this is the first report of a comparative AFM study to monitor the effects of a mono- and a binuclear platinum anti-cancer drug on DNA structure. These observations should provide clues towards explaining the distinct biological activities of the two drugs.     

Role of nephrin in podocyte injury induced by angiotension II

Objective: To investigate the function of nephrin in podocytes and its relation to proteinuria in kidney diseases, and to study more clearly theoretical basis for the molecular mechanism of losartan anti-proteinuria and the special beneficial effects of losartan on podocyte injury. Methods: Experiment set up control, Ang II and losartan group. Cell morphology was observed perturbation, and using image processing software to analyze the cell body of cell morphology and size of the difference after 8?h, 24?h and 48?h. Detecting nephrin mRNA and protein expression changes by real time PCR (RT-PCR) and western blotting at different time points. Results: Podocyte cell bodies were significantly reduced after Ang II injury (p?<?0.01), losartan directly reduces the rate of apoptotic podocytes induced by Ang. Apoptotic podocytes may related to the decrease of nephrin mRNA and protein expressions, losartan reduced the apoptosis and proteinuria by declining nephrin mRNA and protein expressions. Conclusion: Ang II induced podocyte injury caused abnormal expression and distribution of nephrin in podocytes, losartan maybe maintain the stability of nephrin expression and the integrity of hole diaphragm (SD) structure and function by blocking the signal path, playing a important role in protection mechanisms of anti-proteinuria. Our findings provide some possible clues for further exploring the pharmacological targets to the proteinuria. These novel findings provide new insights into the beneficial effects of losartan on podocytes directly.     

荧光标记法检测不同毒物对细胞骨架的影响

细胞骨架(Cytoskeleton)主要由微管(Microtubule,MT)、微丝(Microfilament,MF)以及中间丝(Intermediate filament,IF)这三种类型组成。它们在细胞的形态维持、物质运输、信号转导、能量转换及细胞的运动和分裂等多个过程中发挥着重要的作用。其中,由肌动蛋白组成的微丝是真核细胞中含量最丰富的一种蛋白复合体,以解聚时的球状肌动蛋白G-actin(Globular actin)或聚合时的纤丝状肌动蛋白F-actin(Filamen-tous actin)形式存在。正常细胞中肌动蛋白两种形态的转换处于动态平衡,共同行使细胞的变形运动、胞质分裂、基质附着和胞间连接等多…     

Morphological and physiological changes in Streptomyces lividans induced by different yeasts

Streptomyces development is a complex process that eventually finishes with the formation of individual unigenomic spores from the aerial hyphae. Intraspecific and interspecific signals must play a key role in triggering or blocking this process. Here we show that interaction between two types of microorganisms, Streptomyces and yeasts, leads to alteration of the Streptomyces developmental program. This alteration is due to the action of invertase produced by the yeast on the sucrose present in the culture media, making glucose and fructose readily available for growth.     

Structural changes in the lungs induced by different levels of hyperbaric oxygenation

Morphological and ultrastructural changes in the lungs of 30 rabbits placed into the altitude chamber with 100% O2 and the pressure of 2, 2.5, 3 and 4 ata for 60 min daily during 1, 2 and 3 weeks have been studied. Morphological changes in the lungs were shown to depend on the degree and duration of oxygen pressure. 2 ata for 60 min daily during two weeks or 2.5 ata for 60 min daily during one week were considered to be safe regimens of hyperbaric oxygenation. Microcirculatory disorders and dystrophic changes of the aero-hematogenic barrier (AHB), its increased permeability, the development of intraalveolar and interstitial edema are observed in the lungs at a higher pressure of 3 or 4 ata. The endothelium and type I alveolocytes are more sensible to high doses of hyperbaric oxygenation. Hydropic degeneration and exfoliation of cells from the basilar membrane are gradually increasing. Type II alveolocytes are more stable to the destructive action of hyperbaric oxygenation. Greater dystrophic changes in other AHB elements are associated with the hypertrophy of mitochondria and lamellar bodies. The described AHB changes are more expressed in atelectasis areas.     

Cathepsin C is a novel mediator of podocyte and renal injury induced by hyperglycemia

A growing body of evidence suggests a role of proteolytic enzymes in the development of diabetic nephropathy. Cathepsin C (CatC) is a well-known regulator of inflammatory responses, but its involvement in podocyte and renal injury remains obscure. We used Zucker rats, a genetic model of metabolic syndrome and insulin resistance, to determine the presence, quantity, and activity of CatC in the urine. In addition to the animal study, we used two cellular models, immortalized human podocytes and primary rat podocytes, to determine mRNA and protein expression levels via RT-PCR, Western blot, and confocal microscopy, and to evaluate CatC activity. The role of CatC was analyzed in CatC-depleted podocytes using siRNA and glycolytic flux parameters were obtained from extracellular acidification rate (ECAR) measurements. In functional analyses, podocyte and glomerular permeability to albumin was determined. We found that podocytes express and secrete CatC, and a hyperglycemic environment increases CatC levels and activity. Both high glucose and non-specific activator of CatC phorbol 12-myristate 13-acetate (PMA) diminished nephrin, cofilin, and GLUT4 levels and induced cytoskeletal rearrangements, increasing albumin permeability in podocytes. These negative effects were completely reversed in CatC-depleted podocytes. Moreover, PMA, but not high glucose, increased glycolytic flux in podocytes. Finally, we demonstrated that CatC expression and activity are increased in the urine of diabetic Zucker rats. We propose a novel mechanism of podocyte injury in diabetes, providing deeper insight into the role of CatC in podocyte biology.     

Structural changes in retinol binding protein induced by retinol removal. A molecular dynamics study

Relationships between structure and function for retinol binding protein (RBP) are elucidated with help of a 2.0 A resolution X-ray structure of the holo-protein and an average molecular dynamics (MD) structure of the apo-form. Comparisons between MD simulations of both the apo- and holo-forms with the X-ray holo-structure show conformational changes in apo-RBP that may be functionally significant. The average three dimensional structure obtained for apo-RBP is compared to the related protein apo-beta-lactoglobulin. Available biochemical information is consistent with structure/function relationships derived here.     

Renal cell apoptosis induced by nephrotoxic drugs: cellular and molecular mechanisms and potential approaches to modulation

Apoptosis plays a central role not only in the physiological processes of kidney growth and remodeling, but also in various human renal diseases and drug-induced nephrotoxicity. We present in a synthetic fashion the main molecular and cellular pathways leading to drug-induced apoptosis in kidney and the mechanisms regulating it. We illustrate them using three main nephrotoxic drugs (cisplatin, gentamicin, and cyclosporine A). We discuss the main regulators and effectors that have emerged as key targets for the design of therapeutic strategies. Novel approaches using gene therapy, antisense strategies, recombinant proteins, or compounds obtained from both classical organic and combinatorial chemistry are examined. Finally, key issues that need to be addressed for the success of apoptosis-based therapies are underlined.