Loss of kindlin-1, a human homolog of the Caenorhabditis elegans actin-extracellular-matrix linker protein UNC-112, causes Kindler syndrome

Kindler syndrome is an autosomal recessive disorder characterized by neonatal blistering, sun sensitivity, atrophy, abnormal pigmentation, and fragility of the skin. Linkage and homozygosity analysis in an isolated Panamanian cohort and in additional inbred families mapped the gene to 20p12.3. Loss-of-function mutations were identified in the FLJ20116 gene (renamed “KIND1” [encoding kindlin-1]). Kindlin-1 is a human homolog of the Caenorhabditis elegans protein UNC-112, a membrane-associated structural/signaling protein that has been implicated in linking the actin cytoskeleton to the extracellular matrix (ECM). Thus, Kindler syndrome is, to our knowledge, the first skin fragility disorder caused by a defect in actin-ECM linkage, rather than keratin-ECM linkage.     

Effect of human urotensin-II infusion on hemodynamics and cardiac function

Recent studies have shown that the vasoactive peptide urotensin-II (U-II) exerts a wide range of action on the cardiovascular system of various species. In the present study, we determined the in vivo effects of U-II on basal hemodynamics and cardiac function in the anesthetized intact rat. Intravenous bolus injection of human U-II resulted in a dose-dependent decrease in mean arterial pressure and left ventricular systolic pressure. Cardiac contractility represented by +/-dP/dt was decreased after injection of U-II. However, there was no significant change in heart rate or diastolic pressure. The present study suggests that upregulation of myocardial U-II may contribute to impaired myocardial function in disease conditions such as congestive heart failure.     

Elucidation of the metabolic fate of glucose in the filamentous fungus Trichoderma reesei using expressed sequence tag (EST) analysis and cDNA microarrays

Despite the intense interest in the metabolic regulation and evolution of the ATP-producing pathways, the long standing question of why most multicellular microorganisms metabolize glucose by respiration rather than fermentation remains unanswered. One such microorganism is the cellulolytic fungus Trichoderma reesei (Hypocrea jecorina). Using EST analysis and cDNA microarrays, we find that in T. reesei expression of the genes encoding the enzymes of the tricarboxylic acid cycle and the proteins of the electron transport chain is programmed in a way that favors the oxidation of pyruvate via the tricarboxylic acid cycle rather than its reduction to ethanol by fermentation. Moreover, the results indicate that acetaldehyde may be channeled into acetate rather than ethanol, thus preventing the regeneration of NAD(+), a pivotal product required for anaerobic metabolism. The studies also point out that the regulatory machinery controlled by glucose was most probably the target of evolutionary pressure that directed the flow of metabolites into respiratory metabolism rather than fermentation. This finding has significant implications for the development of metabolically engineered cellulolytic microorganisms for fuel production from cellulose biomass.     

Protective effect of aminoguanidine against nephrotoxicity induced by cisplatin in normal rats

The effect of aminoguanidine (AG) on nephrotoxicity induced by cisplatin (CDDP) was investigated. A single dose of CDDP (7.5 mg/kg i.p.) induced nephrotoxicity, manifested biochemically by a significant elevation in serum urea, creatinine and a severe decrease in serum albumin. Moreover, marked increases in kidney weight, urine volume and urinary excretion of albumin were observed. Nephrotoxicity was further confirmed by a significant decrease in glutathione-S-transferase (GST, E.C. 2.5.1.18), glutathione peroxidase (GSH-Px, E.C. 1.11.1.9) and catalase (E.C. 1.11.1.6) and a significant increase in lipid peroxides measured as malondialdhyde (MDA) in kidney homogenates. Administration of AG (100 mg/kg per day p.o.) in drinking water 5 days before and 5 days after CDDP injection produced a significant protection against nephrotoxicity induced by CDDP. The amelioration of nephrotoxicity was evidenced by significant reductions in serum urea and creatinine concentrations. In addition, AG tended to normalize decreased levels of serum albumin. Urine volume, urinary excretions of albumin and GST and kidney weight were significantly decreased. Moreover, AG prevented the rise of MDA and the reduction of GST and GSH-Px activities in the kidney. These results suggest that AG has a protective effect on nephrotoxicity induced by CDDP and it may therefore improve the therapeutic index of CDDP.     

Synthesis and anti-HBV activity of thiouracils linked via S and N-1 to the 5-position of methyl beta-D-ribofuranoside

Reverse nucleoside derivatives of 2-(methylsulfanyl)uracils 6a-d were prepared by treating of the sodium salt of 2-(methylsulfanyl)uracils (5a-d) with methyl 2,3-O-isopropylidene-5-O-p-toluenesulfonyl-beta-D-ribofuranoside (2). The alkylation of 2-thiouracils 4a-d with methyl 5-deoxy-5-iodo-2,3-O-isopropylidene-D-ribofuranoside (3) afforded the corresponding S-ribofuranoside derivatives 8a-d. Deisopropylidenation of 6a-d and 8a-d afforded the corresponding deprotected derivatives 7a-d and 9a-d, respectively. The Anti-HBV activity of selected compounds was studied.     

Non-peptide alphavbeta3 antagonists. Part 6: design and synthesis of alphavbeta3 antagonists containing a pyridone or pyrazinone central scaffold

Two novel series of small-molecule RGD mimetics containing either a substituted pyridone or pyrazinone central constraint were prepared. Modification of the beta-alanine 3-substituent produced compounds that are potent and selective alpha(v)beta(3) antagonists and exhibit a range of physicochemical properties.     

Ultrastructural changes in the muscles,midgut, hemopoietic organ,imaginal discs and Malpighian tubules of the mosquito Aedes aegypti larvae infected by the fungus Coelomomyces stegomyiae

Fungi belonging to the genus Coelomomyces can infect mosquito larvae and develop within the larval hemocoel. To examine fungal development, Aedesaegypti larvae infected with Coelomomyces stegomyiae Keilin were fixed, embedded and sectioned for both light and electron microscopy. While fungal hyphae of C. stegomyiae did not invade cells other than the cuticular epithelial cells, they did penetrate a number of tissues including muscles, midgut, hemopoietic organ, imaginal discs, and Malpighian tubules. This revised version was published online in July 2006 with corrections to the Cover Date.     

Lung epithelial barrier function and wound healing are decreased by IL-4 and IL-13 and enhanced by IFN-gamma

To understand theeffects of cytokines on epithelial cells in asthma, we haveinvestigated the effects of interleukin (IL)-4, IL-13, and interferon(IFN)- on barrier function and wound healing in Calu-3 human lungepithelial cells. IL-4 and IL-13 treatment of Calu-3 cells grown onTranswell filters resulted in a 70-75% decrease in barrierfunction as assessed by electrophysiological and[¹⁴C]mannitol flux measurements. In contrast, IFN-enhanced barrier function threefold using these same parameters. Cellstreated concurrently with IFN- and IL-4 or IL-13 showed an initialdecline in barrier function that was reversed within 2 days, resulting in barrier levels comparable to control cells. Analysis of the tightjunction-associated proteins ZO-1 and occludin showed that IL-4 andIL-13 significantly reduced ZO-1 expression and modestly decreasedoccludin expression compared with controls. IFN-, quite unexpectedlygiven its enhancing effect on barrier function, reduced expression ofZO-1 and occludin to almost undetectable levels compared with controls.In wound-healing assays of cells grown on collagen I, IL-4 and IL-13decreased migration, whereas IFN- treatment enhanced migration,compared with control cells. Addition of IFN-, in combination withIL-4 or IL-13, restored migration of cells to control levels. Migrationdifferences observed between the various cytokine treatments wascorrelated with expression of the collagen I-binding₂₁-integrin at the leading edge of cellsat the wound front; ₂₁-integrinexpression was decreased in IFN--treated cells compared withcontrols, whereas it was highest in IL-4- and IL-13-treated cells.These results demonstrate that IL-4 and IL-13 diminish the capacity ofCalu-3 cells to maintain barrier function and repair wounds, whereasIFN- promotes epithelial restitution by enhancing barrier functionand wound healing.

     

Differential steric effects in the axial ligation of pyridine and imidazole to α- and β-alkylcobinamides

One subclass of B₁₂-requiring enzymes is now known to bind their B₁₂ coenzymes “base-off,” with a histidine residue from the protein supplying an imidazole ligand to the cobalt center. Recent results from Sirovatka and Finke (J.M. Sirovatka and R.G. Finke, J.Am. Chem. Soc. 119, (1997) 3057) show that imidazole has an extraordinary trans effect on the mode of carbon–cobalt bond cleavage in coenzyme B₁₂ analogs, compared to pyridine or the natural 5,6-dimethylbenzimidazole ligand, and it was suggested that a differential steric effect could, in part, account for the uniqueness of the imidazole ligand. Such a differential steric effect for imidazole and pyridine is now demonstrated by studies of the thermodynamics of ligation of these ligands to the α and β diastereomers of two alkylcobinamides (RCbi⁺s, derivatives of cobalamins which lack the normal axial nucleotide) based on the known differences in steric crowding of the α (“lower”) and β (“upper”) axial ligand positions of cobalt corrinoids. Imidazole binds more tightly than pyridine to both diastereomers of NCCH₂Cbi⁺ and CF₃Cbi⁺, in all cases due to a more favorable entropy change, which is the result of lowered steric interference with corrin side chain thermal motions.     

Differential protein expression profile in the liver of pikeperch (Sander lucioperca) larvae fed with increasing levels of phospholipids

A comparative proteomic approach was used to assess the protein expression profile in the liver of 34 days old pikeperch larvae fed from day 10 post hatching, with three isoproteic and isolipidic formulated diets varying by their phospholipid (PL) contents (% dry diet weight): 1.4% (PL1), 4.7% (PL5) and 9.5% (PL9). Using 2D-DIGE minimal labelling of liver extracts, we were able to show 56 protein spots with a differential intensity (p < 0.05) depending on the dietary PL content. Among these spots, 11 proteins were unambiguously identified using nanoLC-MS/MS tandem mass spectrometry. In the PL9 larvae, our results indicate that the glycolytic pathway could be down-regulated due to the under-expression of the fructose biphosphate aldolase B and the phosphoglucomutase 1. Meanwhile, propionyl coenzyme A carboxylase (a gluconeogenic enzyme) was under-expressed. In addition, another gluconeogenic and lipogenic enzyme, pyruvate carboxylase, was identified in 3 different spots as being under-expressed in fish fed with the intermediate PL level (PL5). A high PL content increased the expression of sarcosine dehydrogenase, an enzyme involved in methionine metabolism, along with vinculin, a structural protein. Moreover, several stress proteins (glutathione S-transferase M, glucose regulated protein 75 and peroxiredoxin-1) were modulated in response to the dietary PL level and fatty acid composition. In the larvae fed with the lowest dietary PL content (PL1), over-expression of both GSTM and GRP75 might indicate a cellular stress in this experimental treatment, while the under-expression of Prx1 might indicate a lower defence against oxidative stress. In conclusion, this nutriproteomic approach showed significant modifications of protein expression in the liver of pikeperch larvae fed different PL contents, highlighting the importance of these nutrients and their influence on metabolism processes and on stress response.