The discovery of Streptomyces-produced streptomycin founded the age of tuberculosis therapy. Despite the subsequent development of a curative regimen for this disease, tuberculosis remains a worldwide problem, and the emergence of multidrug-resistant Mycobacterium tuberculosis has prioritized the need for new drugs. Here we show that new optimized derivatives from Streptomyces-derived griselimycin are highly active against M. tuberculosis, both in vitro and in vivo, by inhibiting the DNA polymerase sliding clamp DnaN. We discovered that resistance to griselimycins, occurring at very low frequency, is associated with amplification of a chromosomal segment containing dnaN, as well as the ori site. Our results demonstrate that griselimycins have high translational potential for tuberculosis treatment, validate DnaN as an antimicrobial target, and capture the process of antibiotic pressure-induced gene amplification.

A key mechanism underlying physiological angiogenesis of the human endometrium is its ability to regenerate the vascular capillary network and to perform vascular remodeling (i.e., development of spiral arteries). Vascular endothelial growth factor (VEGF) is associated with angiogenesis and capillary permeability in this tissue. VEGF is expressed as several spliced variants, its main human isoforms contain 121 and 165 aa; 17␤-estradiol (E2) increases endometrial VEGF, possibly in all isoforms. Here we show that progesterone (P) selectively increases the expression of the VEGF189 (V189) isoform in the human uterus. V189 is identified in the conditioned medium of stromal cells treated with E2 ؉ P; its presence in this in vitro model of decidual stromal cells is detected after 6 -8 days, using ELISA, and after 8 -10 days, using Western blot analysis with different antibodies, including one specific for V189. The secretion pattern of V189 parallels that of the decidual protein IGFBP-1. V189 is secreted as a native isoform, as compared with the migration of recombinant V189 by SDS͞PAGE. In situ hybridization and immunocytochemistry, performed on the same biopsies, suggest that decidual cells express V189 during the midlate secretory phase of the menstrual cycle and early gestation. Finally, using an in vivo permeability assay, we show that native V189 increases capillary permeability. These observations demonstrate that P regulates V189 expression in decidual cells, which could have important implications for understanding uterine vascular remodeling and implantation, and may be relevant in a range of disease states such as edema and irregular bleeding.A s a tissue that exhibits rapid cyclic changes (1), the human endometrium is a good model for the study of physiological angiogenesis, which is under the control of 17␤ estradiol (E 2 ), progesterone (P), and vascular endothelial growth factor (VEGF) (2-7).VEGF is a protein with angiogenic activity and is a potent stimulator of microvascular permeability (8, 9); it plays an important role in physiological and pathological neovascularization, via its receptors Flt-1͞VEGFR1 and Flk-1͞VEGFR2 (10-13). Molecular cloning of the cDNA for VEGF revealed that differential exon splicing generates several isoforms containing 121, 165, 189, and 206 aa (V 121, V 165, V 189, and V 206 ) (14, 15). In most systems V 121 and V 165 are the major species expressed, whereas V 189 is only minimally present and V 206 is limited to embryonic tissue (9, 15). The different isoforms appear to have similar functions, but differ in their binding affinity for extracellular matrix (ECM). In contrast to VEGF 121 , which is secreted and found freely soluble in the culture medium, the bioavailability of VEGF 165 and to a greater extent V 189 appears to be regulated by binding to heparan sulfate proteoglycans (HSPG) in the ECM (9, 16). Bound VEGF isoforms could provide a reserve of growth factors available after cleavage by heparinase or urokinase-type plasminogen activator (uPA) (17, 18).Previous stud...

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