Dissecting the basis of nongenomic activation of endothelial nitric oxide synthase by estradiol: role of ERalpha domains with known nuclear functions

Estradiol stimulates endothelial nitric oxide synthase (eNOS) via the activation of plasma membrane (PM)-associated estrogen receptor (ER) alpha. The process requires Src and erk signaling and eNOS phosphorylation by phosphoinositide 3-kinase (PI3 kinase)-Akt kinase, with Src and PI3 kinase associating with ERalpha upon ligand activation. To delineate the basis of nongenomic eNOS stimulation, the potential roles of ERalpha domains necessary for classical nuclear function were investigated in COS-7 cells. In cross-linking studies, estradiol-17beta (E2) caused PM-associated ERalpha to form dimers. However, eNOS activation by E2 was unaltered for a dimerization-deficient mutant ERalpha (ERalphaL511R). In contrast, ERalpha mutants lacking the nuclear localization signals (NLS), NLS2,3 (ERalphaDelta250-274) or the DNA binding domain (ERalphaDelta185-251), which targeted normally to PM and caveolae/rafts, were incapable of activating eNOS. The loss of NLS2/NLS3 prevented Src and erk activation, and it altered ligand-induced PI3 kinase-ERalpha interaction and prevented eNOS phosphorylation. Loss of the DNA binding domain did not change E2 activation of Src or erk, but ligand-induced PI3 kinase-ERalpha binding and eNOS phosphorylation did not occur. Thus, dimerization is not required for ERalpha coupling to eNOS; however, NLS2/NLS3 plays a role in Src activation, and the DNA binding region is involved in the dynamic interaction between ERalpha and PI3 kinase.     

Vasopressors for the Treatment of Septic Shock: Systematic Review and Meta-Analysis

Objective

International guidelines recommend dopamine or norepinephrine as first-line vasopressor agents in septic shock. Phenylephrine, epinephrine, vasopressin and terlipressin are considered second-line agents. Our objective was to assess the evidence for the efficiency and safety of all vasopressors in septic shock.

Methods

Systematic review and meta-analysis. We searched electronic database of MEDLINE, CENTRAL, LILACS and conference proceedings up to June 2014. We included randomized controlled trials comparing different vasopressors for the treatment of adult patients with septic shock. Primary outcome was all-cause mortality. Other clinical and hemodynamic measurements were extracted as secondary outcomes. Risk ratios (RR) and mean differences with 95% confidence intervals (CI) were pooled.

Results

Thirty-two trials (3,544 patients) were included. Compared to dopamine (866 patients, 450 events), norepinephrine (832 patients, 376 events) was associated with decreased all-cause mortality, RR 0.89 (95% CI 0.81-0.98), corresponding to an absolute risk reduction of 11% and number needed to treat of 9. Norepinephrine was associated with lower risk for major adverse events and cardiac arrhythmias compared to dopamine. No other mortality benefit was demonstrated for the comparisons of norepinephrine to epinephrine, phenylephrine and vasopressin / terlipressin. Hemodynamic data were similar between the different vasopressors, with some advantage for norepinephrine in central venous pressure, urinary output and blood lactate levels.

Conclusions

Evidence suggests a survival benefit, better hemodynamic profile and reduced adverse events rate for norepinephrine over dopamine. Norepinephrine should be regarded as the first line vasopressor in the treatment of septic shock.     

PAX6 Regulates Melanogenesis in the Retinal Pigmented Epithelium through Feed-Forward Regulatory Interactions with MITF

During organogenesis, PAX6 is required for establishment of various progenitor subtypes within the central nervous system, eye and pancreas. PAX6 expression is maintained in a variety of cell types within each organ, although its role in each lineage and how it acquires cell-specific activity remain elusive. Herein, we aimed to determine the roles and the hierarchical organization of the PAX6-dependent gene regulatory network during the differentiation of the retinal pigmented epithelium (RPE). Somatic mutagenesis of Pax6 in the differentiating RPE revealed that PAX6 functions in a feed-forward regulatory loop with MITF during onset of melanogenesis. PAX6 both controls the expression of an RPE isoform of Mitf and synergizes with MITF to activate expression of genes involved in pigment biogenesis. This study exemplifies how one kernel gene pivotal in organ formation accomplishes a lineage-specific role during terminal differentiation of a single lineage.