Mycolic acids consist of long-chain alpha-alkyl-beta-hydroxy fatty acids that are produced by successive rounds of elongation catalysed by a type II fatty acid synthase (FAS-II). A key feature in the elongation process is the condensation of a two-carbon unit from malonyl-acyl-carrier protein (ACP) to a growing acyl-ACP chain catalysed by a beta-ketoacyl-ACP synthase (Kas). In the present study, we provide evidence that kasA from Mycobacterium tuberculosis encodes an enzyme that elongates in vivo the meromycolate chain, in both Mycobacterium smegmatis and Mycobacterium chelonae. We demonstrate that KasA belongs to the FAS-II system, which utilizes primarily palmitoyl-ACP rather than short-chain acyl-ACP primers. Furthermore, in an in vitro condensing assay using purified recombinant KasA, palmitoyl-AcpM and malonyl-AcpM, KasA was found to express Kas activity. Also, mutated KasA proteins, with mutation of Cys(171), His(311), Lys(340) and His(345) to Ala abrogated the condensation activity of KasA in vitro completely. Finally, purified KasA was highly sensitive to cerulenin, a well-known inhibitor of Kas, which may lead to the development of novel anti-mycobacterial drugs targeting KasA.

The ets genes family encodes a group of proteins which function as transcription factors under physiological conditions. We report here that the Erg proteins, members of the Ets family, form homo and heterodimeric complexes in vitro. We demonstrate that the Ergp55 protein isoform forms dimers with itself and with the two other isoforms, Ergp49 and Ergp38. Using a set of Erg protein deletion mutants, we de®ne two distinct domains independently involved in dimerization. The ®rst one is located in the amino-terminal part of the protein containing the pointed domain (PNT), conserved in a subset of Ets proteins. The second one resides within the ETS domain, the DNA-binding domain. We also show that the Erg protein central region behaves as an inhibitory domain of dimerization and its removal enhances the Ergp55 transactivation properties. Furthermore, Ergp55 forms heterodimers with some other Ets proteins. Among the latter, we show that Fli-1, Ets-2, Er81 and Pu-1 physically interact with Erg. Finally, we show that the formation of the previously described ternary complex Ergp55/Fos/jun is mediated by ETS domain and Jun protein, while the ternary complex Ergp49/Fos/Jun is mediated by Fos protein.

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The Erg gene belongs to the Ets family encoding a class of transcription factors. To gain new insight on the in vivo functional specificity of the Erg gene within the wide Ets family, we used in situ hybridization to determine its expression pattern during murine embryogenesis. We found that the Erg gene expression predominates in mesodermal tissues, including the endothelial, precartilaginous and urogenital areas. A specific Erg gene expression was also identified in migrating neural crest cells. A comparison with Fli-1, the most closely Erg-related gene, revealed that both gene expressions partially overlap, suggesting that they may contribute to related functions in these tissues. Like other Ets family genes, Erg seems involved in several fundamental developmental steps in murine embryogenesis, including epithelio-mesenchymal transition, cell migration, settlement and differentiation.

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Objective-To determine if a new inhibitor, esculetin (EST), can block resorption of cartilage. Methods-Interleukin 1 (IL1 , 0.04-5 ng/ ml) and oncostatin M (OSM, 0.4-50 ng/ml) were used to stimulate the release of proteoglycan and collagen from bovine nasal cartilage and human articular cartilage in explant culture. Proteoglycan and collagen loss were assessed by dimethylmethylene blue and hydroxyproline assays, respectively. Collagenase levels were measured by assay of bioactivity and by enzyme linked immunosorbent assay (ELISA). The eVects of EST on the expression of matrix metalloproteinases (MMPs) and tissue inhibitor of metalloproteinase-1 (TIMP-1) in the transformed human chondrocyte cell line T/C28a4 were assessed by northern blot analysis. TIMP-1 protein levels were assayed by ELISA. The eVect of EST on the MMP-1 promoter was assessed using a promoter-luciferase construct in transient transfection studies. Results-EST inhibited proteoglycan and collagen resorption in a dose dependent manner with significant decreases seen at 66 µM and 100 µM EST, respectively. Collagenolytic activity was significantly decreased in bovine nasal cartilage cultures. In human articular cartilage, EST also inhibited IL1 + OSM stimulated resorption and decreased MMP-1 levels. TIMP-1 levels were not altered compared with controls. In T/C28a4 chondrocytes the IL1 + OSM induced expression of MMP-1, MMP-3, and MMP-13 mRNA was reduced to control levels by 250 µM EST. TIMP-1 mRNA levels were unaffected by EST treatment. All cytokine stimulation of an MMP-1 luciferasepromoter construct was lost in the presence of the inhibitor. Conclusion-EST inhibits degradation of bovine nasal cartilage and human articular cartilage stimulated to resorb with IL1 + OSM.

Background Inflammatory skin disorders, including atopic dermatitis (AD), associated pruritus and sensitive skin, have a complex multifactorial pathogenesis including neurogenic inflammation involving the release in blood and skin of neurotransmitters such as substance P (SP). Aims and Methods In vitro models evaluated the effect of the original biological extract of Aquaphilus dolomiae extract‐G3 (ADE‐G3) on cutaneous neurogenic inflammation. Results ADE‐G3 significantly inhibited SP‐stimulated release of IL‐1β and TNF‐α from normal human epidermal keratinocytes; significantly and dose‐dependently inhibited SP‐stimulated activation of human mast cells; significantly inhibited veratridine‐stimulated release of SP from human sensory neurons; modulated expression of genes involved in lipid synthesis, innate immunity, corneocyte scaffolding and epidermal differentiation in a histamine‐sensitized reconstructed human epidermis model; and, when applied topically to ex vivo human explants, inhibited IL‐8 and histamine release. Conclusions Topically applied ADE‐G3, once formulated, may improve neuro‐inflammation in patients with inflammatory skin disorders.