ALBERT

Beschreibung: Postmenopausal women have an increased risk of cardiovascular disease, and heart disease is the leading cause of death in postmenopausal American women. Conventional hormone replacement therapy has been shown to result in an increase in thrombotic events in large prospective clinical trials including HERS I, and the recently halted Women’s Health Initiative. One possible mechanism for this observed increase is the unfavorable net effects of conjugated equine estrogens and medroxyprogesterone acetate on the hemostatic balance and inflammatory factors. An estimated 50 million American women are peri or postmenopausal and clinical therapies for menopausal symptoms remain a significant challenge in light of the known thrombotic risks. In this prospective blinded study, we examined the short-term effect of topical progesterone cream on menopausal symptom relief in 30 healthy postmenopausal women. Potential adverse effects of topical progesterone on hemostatic and inflammatory factors and cortisol levels were also examined. Subjects were randomized to first receive either 20 mg of topical progesterone cream or placebo cream for 4 weeks. Following a subsequent 4-week washout period, subjects were crossed over to either placebo cream or active drug for an additional 4-week period. In each case, progesterone and cortisol levels were monitored by salivary sampling. Baseline values, 4-week follow-up values and end-of-study values were also obtained for the Greene Climacteric Scale, total factor VII:C, factor VIIa, factor V, fibrinogen, antithrombin, PAI-1, CRP, TNFα, and IL-6. For subjects receiving 20 mg of topical progesterone cream for 4 weeks, Greene Climacteric Scale scores were consistently and significantly improved (decreased) over baseline, demonstrating significant relief from menopausal symptoms. In addition, in a subpopulation of hypercortisolemic women, topical progesterone was associated with a favorable decrease in nocturnal cortisol. Surprisingly, and in sharp contrast to earlier studies with conventional hormone replacement therapy, topical progesterone had no effect on any of the hemostatic components examined: total factor VII:C, factor VIIa, factor V, fibrinogen, antithrombin, and PAI-1 levels were all unchanged. Levels of CRP, TNFα and IL-6 also remained unchanged. From this study we conclude that administration of topical progesterone cream at a daily dose of 20 mg significantly relieves menopausal symptoms in postmenopausal women without adversely altering prothrombotic potential. Since the thrombotic complications that are typically observed with conventional hormone replacement therapy do not seem to occur with topical progesterone, this treatment should be seriously considered as an effective and safe alternative clinical therapy for women suffering from menopausal symptoms.

Beschreibung: Plants produce an array of natural products with important ecological functions. These compounds are often decorated with oligosaccharide groups that influence bioactivity, but the biosynthesis of such sugar chains is not well understood. Triterpene glycosides (saponins) are a large family of plant natural products that determine important agronomic traits, as exemplified by avenacins, antimicrobial defense compounds produced by oats. Avenacins have a branched trisaccharide moiety consisting ofl-arabinose linked to 2d-glucose molecules that is critical for antifungal activity. Plant natural product glycosylation is usually performed by uridine diphosphate-dependent glycosyltransferases (UGTs). We previously characterized the arabinosyltransferase that initiates the avenacin sugar chain; however, the enzymes that add the 2 remainingd-glucose molecules have remained elusive. Here we characterize the enzymes that catalyze these last 2 glucosylation steps. AsUGT91G16 is a classical cytosolic UGT that adds a 1,2-linkedd-glucose molecule tol-arabinose. Unexpectedly, the enzyme that adds the final 1,4-linkedd-glucose (AsTG1) is not a UGT, but rather a sugar transferase belonging to Glycosyl Hydrolase family 1 (GH1). Unlike classical UGTs, AsTG1 is vacuolar. Analysis of oat mutants reveals thatAsTG1corresponds toSad3, a previously uncharacterized locus shown by mutation to be required for avenacin biosynthesis.AsTG1andAsUGT91G16form part of the avenacin biosynthetic gene cluster. Our demonstration that a vacuolar transglucosidase family member plays a critical role in triterpene biosynthesis highlights the importance of considering other classes of carbohydrate-active enzymes in addition to UGTs as candidates when elucidating pathways for the biosynthesis of glycosylated natural products in plants.

Beschreibung: We used the nanometer-wide tubules of the transverse tubular (t)-system of human skeletal muscle fibers as sensitive sensors for the quantitative monitoring of the Ca2+-handling properties in the narrow junctional cytoplasmic space sandwiched between the tubular membrane and the sarcoplasmic reticulum cisternae in single muscle fibers. The t-system sealed with a Ca2+-sensitive dye trapped in it is sensitive to changes in ryanodine receptor (RyR) Ca2+ leak, the store operated calcium entry flux, plasma membrane Ca pump, and sodium–calcium exchanger activities, thus making the sealed t-system a nanodomain Ca2+ sensor of Ca2+ dynamics in the junctional space. The sensor was used to assess the basal Ca2+-handling properties of human muscle fibers obtained by needle biopsy from control subjects and from people with a malignant hyperthermia (MH) causative RyR variant. Using this approach we show that the muscle fibers from MH-susceptible individuals display leakier RyRs and a greater capacity to extrude Ca2+ across the t-system membrane compared with fibers from controls. This study provides a quantitative way to assess the effect of RyR variants on junctional membrane Ca2+ handling under defined ionic conditions.

Beschreibung: It has always been difficult to account for the evolution of certain human characters such as language, empathy, and altruism via individual reproductive success. However, the striatum, a subcortical region originally thought to be exclusively motor, is now known to contribute to social behaviors and “personality styles” that may link such complexities with natural selection. We here report that the human striatum exhibits a unique neurochemical profile that differs dramatically from those of other primates. The human signature of elevated striatal dopamine, serotonin, and neuropeptide Y, coupled with lowered acetylcholine, systematically favors externally driven behavior and greatly amplifies sensitivity to social cues that promote social conformity, empathy, and altruism. We propose that selection induced an initial form of this profile in early hominids, which increased their affiliative behavior, and that this shift either preceded or accompanied the adoption of bipedality and elimination of the sectorial canine. We further hypothesize that these changes were critical for increased individual fitness and promoted the adoption of social monogamy, which progressively increased cooperation as well as a dependence on tradition-based cultural transmission. These eventually facilitated the acquisition of language by elevating the reproductive advantage afforded those most sensitive to social cues.

Beschreibung: Conventional protein kinase C (PKC) family members are reversibly activated by binding to the second messengers Ca2+ and diacylglycerol, events that break autoinhibitory constraints to allow the enzyme to adopt an active, but degradation-sensitive, conformation. Perturbing these autoinhibitory constraints, resulting in protein destabilization, is one of many mechanisms by which PKC function is lost in cancer. Here, we address how a gain-of-function germline mutation in PKCα in Alzheimer’s disease (AD) enhances signaling without increasing vulnerability to down-regulation. Biochemical analyses of purified protein demonstrate that this mutation results in an ∼30% increase in the catalytic rate of the activated enzyme, with no changes in the concentrations of Ca2+ or lipid required for half-maximal activation. Molecular dynamics simulations reveal that this mutation has both localized and allosteric effects, most notably decreasing the dynamics of the C-helix, a key determinant in the catalytic turnover of kinases. Consistent with this mutation not altering autoinhibitory constraints, live-cell imaging studies reveal that the basal signaling output of PKCα-M489V is unchanged. However, the mutant enzyme in cells displays increased sensitivity to an inhibitor that is ineffective toward scaffolded PKC, suggesting the altered dynamics of the kinase domain may influence protein interactions. Finally, we show that phosphorylation of a key PKC substrate, myristoylated alanine-rich C-kinase substrate, is increased in brains of CRISPR-Cas9 genome-edited mice containing the PKCα-M489V mutation. Our results unveil how an AD-associated mutation in PKCα permits enhanced agonist-dependent signaling via a mechanism that evades the cell’s homeostatic down-regulation of constitutively active PKCα.