Full-length 66-kDa estrogen receptor ␣ (ER␣) stimulates target gene transcription through two activation functions (AFs), AF-1 in the N-terminal domain and AF-2 in the ligand binding domain. Another physiologically expressed 46-kDa ER␣ isoform lacks the N-terminal A/B domains and is consequently devoid of AF-1. Previous studies in cultured endothelial cells showed that the N-terminal A/B domain might not be required for estradiol (E2)-elicited NO production. To evaluate the involvement of ER␣ AF-1 in the vasculoprotective actions of E2, we generated a targeted deletion of the ER␣ A/B domain in the mouse. In these ER␣AF-1 0 mice, both basal endothelial NO production and reendothelialization process were increased by E2 administration to a similar extent than in control mice. Furthermore, exogenous E2 similarly decreased fatty streak deposits at the aortic root from both ovariectomized 18-week-old ER␣AF-1 ؉/؉ LDLr ؊/؊ (low-density lipoprotein receptor) and ER␣AF-1 0 LDLr ؊/؊ mice fed with a hypercholesterolemic diet. In addition, quantification of lesion size on en face preparations of the aortic tree of 8-month-old ovariectomized or intact female mice revealed that ER␣ AF-1 is dispensable for the atheroprotective action of endogenous estrogens. We conclude that ER␣ AF-1 is not required for three major vasculoprotective actions of E2, whereas it is necessary for the effects of E2 on its reproductive targets. Thus, selective ER modulators stimulating ER␣ with minimal activation of ER␣ AF-1 could retain beneficial vascular actions, while minimizing the sexual effects.atherosclerosis ͉ reendothelialization ͉ vasculoprotection E pidemiological studies have suggested that both endogenous and exogenous estrogens protect women against cardiovascular diseases. Although the cardiovascular protective effect of conjugated equine estrogens was not confirmed in postmenopausal women enrolled in the Women Health Initiative (1), it is now widely accepted that the elevated mean age of the women (10-15 years postmenopause) largely contributed to the lack of prevention (2, 3). Thus, although the cardiovascular effects of estrogens are far more complex than initially assumed, it is clear that these hormones play important roles in vascular physiology and pathophysiology, with potential therapeutic implications. Indeed, various vasculoprotective actions of 17␤-estradiol (E2), such as atheroprotection (4, 5), increase of NO production (6), prevention of endothelial activation (7) or apoptosis (8), and the acceleration of endothelial healing (9) have been extensively described.The main action of E2 is mediated by 2 nuclear receptors, estrogen receptor (ER) ␣ and ER␤, encoded by 2 distinct genes, Esr1 and Esr2, respectively. ER␣, but not ER␤, is necessary and sufficient to mediate most of the vascular effects of E2, such as the increase in basal NO production (6) and the acceleration of reendothelialization (10). ER␣ can be divided into 6 domains from A to F that harbors 2 transactivation functions (AF-1 and AF-2) located within regions ...

Sinorhizobium meliloti is a soil bacterium able to induce the formation of nodules on the root of specific legumes, including alfalfa (Medicago sativa). Bacteria colonize nodules through infection threads, invade the plant intracellularly, and ultimately differentiate into bacteroids capable of reducing atmospheric nitrogen to ammonia, which is directly assimilated by the plant. As a first step to describe global changes in gene expression of S. meliloti during the symbiotic process, we used whole genome microarrays to establish the transcriptome profile of bacteria from nodules induced by a bacterial mutant blocked at the infection stage and from wild-type nodules harvested at various timepoints after inoculation. Comparison of these profiles to those of cultured bacteria grown either to log or stationary phase as well as examination of a number of genes with known symbiotic transcription patterns allowed us to correlate global gene-expression patterns to three known steps of symbiotic bacteria bacteroid differentiation, i.e., invading bacteria inside infection threads, young differentiating bacteroids, and fully differentiated, nitrogen-fixing bacteroids. Finally, analysis of individual gene transcription profiles revealed a number of new potential symbiotic genes.

NF-B is one of the most important elements that coordinate stress-induced, immune, and inflammatory responses. Myxoma virus, a member of the Poxviridae family responsible for rabbit myxomatosis, codes for several factors that help its survival in the host. In this study, we focused on the product of the M150R gene. We show that the protein has nine ankyrin repeats (ANKs), with the eighth having a close similarity with the nuclear localization signal-containing ANK of I-B␣, which regulates NF-B activity by sequestering it in the cytosol. Because the viral protein is targeted to the nucleus, it was named MNF, for myxoma nuclear factor. This localization was lost when the eighth ANK was removed. In tumor necrosis factor alpha-treated cells, MNF and NF-B colocalized as dotted spots in the nucleus. In vivo experiments with a knockout virus showed that MNF is a critical virulence factor, with its deletion generating an almost apathogenic virus. Detailed histological examinations revealed an increase in the inflammatory process in the absence of MNF, consistent with the interference of MNF with the NF-B-induced proinflammatory pathway. Because MNF has homologs in other poxviruses, such as vaccinia, cowpox, and variola viruses, this protein is probably part of a key mechanism that contributes to the immunogenic and pathogenic properties of these viruses.

Objectives-E2 accelerates reendothelialization through estrogen receptor ␣ (ER␣), and we now aimed at defining the precise local and systemic cellular actors of this process. Methods and Results-The respective roles of endothelial and hematopoietic targets of E2 were investigated in a mouse carotid injury model, using confocal microscopy, to follow endothelium repair. Grafting ER␣ Ϫ/Ϫ mice with ER␣ ϩ/ϩ bone marrow (BM) was not sufficient to restore the accelerative effect of E2 on reendothelialization, demonstrating the necessary role of extrahematopoietic ER␣. Using an endothelial-specific inactivation of ER␣ (Cre-Lox system), we showed that endothelial ER␣ plays a pivotal role in this E2 action. Conversely, in ER␣ ϩ/ϩ grafted with ER␣ Ϫ/Ϫ BM, the E2 regenerative effect was abolished, demonstrating that ER␣-expressing hematopoietic cells are also needed. As eNOS expression in BM was required for this action, both endothelial progenitor cells and platelets could be the hematopoietic targets that participate to this beneficial E2 effect. Conclusions-We demonstrate that endothelial ER␣ plays a pivotal role in E2-mediated reendothelialization. However, endothelial targeting alone is not sufficient because the concomitant stimulation of a subpopulation of BM ER␣ is necessary. This cooperation should be taken into account in strategies aimed at optimizing in-stent reendothelialization. Key Words: estradiol Ⅲ reendothelialization Ⅲ carotid injury model Ⅲ endothelium Ⅲ confocal microscopy A ngioplasty followed by stent implantation is a commonly used procedure to treat coronary or peripheral artery stenosis. The major complication of bare metal stent implantation is intrastent stenosis because of neointimal hyperplasia. Drug-eluting stents have emerged as a potential solution against restenosis, 1 but they also inhibit proliferation of endothelial cells. Late thrombosis has become a major concern, because delayed arterial healing, characterized by incomplete reendothelialization, constitutes an important underlying substrate for coagulation. 2,3 Endothelium constitutes an antithrombogenic layer and limits neointima formation, and optimization of endothelial healing should be considered of primary importance. 4 Various treatment strategies to promote endothelial regrowth after arterial injury have been proposed. 5 Administration of angiogenic growth factors such as vascular endothelial growth factor 6 and fibroblast growth factor-2 (FGF-2) 7 increased endothelial healing in animal models. Endogenous mobilization or injection of ex vivo expanded endothelial progenitor cells (EPCs) was associated with enhanced reendothelialization. 8 Pharmacological agents including angiotensin-converting enzyme inhibition, 9 statins, 8,10 and estrogens 11,12 promote endothelial healing.17␤-estradiol (E2), the main endogenous estrogen, exerts many vascular protective effects by increasing basal production of endothelial nitric oxide (NO), 13 accelerating reendothelialization 12,14 or inhibiting neointima formation. 15 We previously demons...