Functional Divergence of Platelet Protein Kinase C (PKC) Isoforms in Thrombus Formation on Collagen

Arterial thrombosis, a major cause of myocardial infarction and stroke, is initiated by activation of blood platelets by subendothelial collagen. The protein kinase C (PKC) family centrally regulates platelet activation, and it is becoming clear that the individual PKC isoforms play distinct roles, some of which oppose each other. Here, for the first time, we address all four of the major platelet-expressed PKC isoforms, determining their comparative roles in regulating platelet adhesion to collagen and their subsequent activation under physiological flow conditions. Using mouse gene knock-out and pharmacological approaches in human platelets, we show that collagen-dependent α-granule secretion and thrombus formation are mediated by the conventional PKC isoforms, PKCα and PKCβ, whereas the novel isoform, PKCθ, negatively regulates these events. PKCδ also negatively regulates thrombus formation but not α-granule secretion. In addition, we demonstrate for the first time that individual PKC isoforms differentially regulate platelet calcium signaling and exposure of phosphatidylserine under flow. Although platelet deficient in PKCα or PKCβ showed reduced calcium signaling and phosphatidylserine exposure, these responses were enhanced in the absence of PKCθ. In summary therefore, this direct comparison between individual subtypes of PKC, by standardized methodology under flow conditions, reveals that the four major PKCs expressed in platelets play distinct non-redundant roles, where conventional PKCs promote and novel PKCs inhibit thrombus formation on collagen.     

Adiponectin and negative mood in healthy premenopausal and postmenopausal women

Negative mood and stress are associated with cardiovascular and metabolic disease. There are likely many physiological mechanisms underlying the poor health outcomes. The relationship of psychological states (negative mood, life stress, and stress-responsive hormones) and adiponectin, an adipokine that promotes insulin sensitivity, was investigated in two separate studies. The two groups of participants included 52 healthy, premenopausal women, and 63 postmenopausal women with a range of stress levels. The relationship between adiponectin and psychological state (perceived stress and negative mood) was examined cross-sectionally in both groups of participants, but also prospectively (1 year later) in the group of postmenopausal women.In premenopausal women, negative mood and nocturnal urinary epinephrine were significantly related to adiponectin, independent of BMI. In postmenopausal women, negative mood was not associated with adiponectin cross-sectionally, but negative mood was a significant predictor for lower levels of adiponectin 1 year later, independent of initial adiponectin concentrations and changes in body mass index. Lastly, having a depressive disorder was related to lower adiponectin. As adiponectin levels are associated with insulin resistance, obesity, and diabetes mellitus, these findings suggest there may be an adiponectin-mediated pathway explaining in part how negative mood affects metabolic health. Mechanistic studies are needed to explore this potential relationship further.     

Exopolysaccharides of Pantoea agglomerans have different priming and eliciting activities in suspension-cultured cells of monocots and dicots

Induced disease resistance of plants is often associated with an enhanced capacity to activate cellular defense responses to pathogen attack, named the "primed" state of the plant. Exopolysaccharides of Pantoea agglomerans have recently been reported as the first priming active component of bacterial origin in wheat cells. We now show that Pantoea exopolysaccharides also prime rice cells for better elicitation of a rapid oxidative burst. In contrast, in tobacco and parsley cell cultures Pantoea exopolysaccharides activate the oxidative burst response directly. Our results point to a different recognition and/or mode of action of Pantoea exopolysaccharides in monocot and dicot plants.     

TGFβ-inducible early gene-1 (TIEG1) mutations in hypertrophic cardiomyopathy

Hypertrophic cardiomyopathy (HCM) is the most common heritable cardiovascular disease. A recent study showed that male KLF10‐encoded TGFβ Inducible Early Gene‐1 knock‐out mice (TIEG^?/?) develop HCM with 13‐fold up‐regulation of PTTG1‐encoded pituitary tumor‐transforming gene 1. We hypothesized TIEG1 could be a novel candidate gene in the pathogenesis of genotype negative HCM in humans, possibly through a loss of its repression on PTTG1 expression. A cohort of 923 unrelated patients from two independent HCM centers was analyzed for mutations in TIEG's four translated exons using DHPLC and direct DNA‐sequencing. Site directed mutagenesis was performed to clone novel variants. The effect of TIEG1 mutations on SMAD7 and PTTG1 promoters was studied using transient transfection and luciferase‐assays. Altered expression of PTTG1 in cardiac tissue was studied by immunohistochemistry (IHC) to determine levels of PTTG1 protein in hypertrophic diseases. Six novel TIEG1 missense mutations were discovered in six patients (two males/four females, mean age at diagnosis 56.2 ± 23 years, MLVWT 20.8 ± 4 mm). Compared to WT TIEG1, five TIEG1 mutants significantly increased PTTG1 promoter function similar to TIEG1^?/?‐mice. By IHC, PTTG1‐protein expression was significantly increased in multiple models of hypertrophic cardiac disease, including TIEG1‐mutation positive HCM compared to normal hearts. This is the first article to associate mutations in TIEG1 to human disease with the discovery of six novel, HCM‐associated variants. Functional assays suggest a role for PTTG1 in the pathogenesis of TIEG1‐mediated HCM. Up‐regulation of PTTG1 seems to be a common pathway in hypertrophic heart disease, including TIEG1‐mediated HCM. J. Cell. Biochem. 113: 1896–1903, 2012. © 2012 Wiley Periodicals, Inc.     

Triggering the production of the cryptic blue pigment indigoidine from Photorhabdus luminescens

The production of the blue pigment indigoidine has been achieved in the entomopathogenic bacterium Photorhabdus luminescens by a promoter exchange and in Escherichia coli following heterologous expression of the biosynthesis gene indC. Moreover, genes involved in the regulation of this previously “silent” biosynthesis gene cluster have been identified in P. luminescens.     

Heritability and phenotypic variation of canine hip dysplasia radiographic traits in a cohort of Australian German shepherd dogs

Canine Hip Dysplasia (CHD) is a common, painful and debilitating orthopaedic disorder of dogs with a partly genetic, multifactorial aetiology. Worldwide, potential breeding dogs are evaluated for CHD using radiographically based screening schemes such as the nine ordinally-scored British Veterinary Association Hip Traits (BVAHTs). The effectiveness of selective breeding based on screening results requires that a significant proportion of the phenotypic variation is caused by the presence of favourable alleles segregating in the population. This proportion, heritability, was measured in a cohort of 13,124 Australian German Shepherd Dogs born between 1976 and 2005, displaying phenotypic variation for BVAHTs, using ordinal, linear and binary mixed models fitted by a Restricted Maximum Likelihood method. Heritability estimates for the nine BVAHTs ranged from 0.14-0.24 (ordinal models), 0.14-0.25 (linear models) and 0.12-0.40 (binary models). Heritability for the summed BVAHT phenotype was 0.30 ± 0.02. The presence of heritable variation demonstrates that selection based on BVAHTs has the potential to improve BVAHT scores in the population. Assuming a genetic correlation between BVAHT scores and CHD-related pain and dysfunction, the welfare of Australian German Shepherds can be improved by continuing to consider BVAHT scores in the selection of breeding dogs, but that as heritability values are only moderate in magnitude the accuracy, and effectiveness, of selection could be improved by the use of Estimated Breeding Values in preference to solely phenotype based selection of breeding animals.     

Environmental Impact of the Production of Mealworms as a Protein Source for Humans – A Life Cycle Assessment

The demand for animal protein is expected to rise by 70–80% between 2012 and 2050, while the current animal production sector already causes major environmental degradation. Edible insects are suggested as a more sustainable source of animal protein. However, few experimental data regarding environmental impact of insect production are available. Therefore, a lifecycle assessment for mealworm production was conducted, in which greenhouse gas production, energy use and land use were quantified and compared to conventional sources of animal protein. Production of one kg of edible protein from milk, chicken, pork or beef result in higher greenhouse gas emissions, require similar amounts of energy and require much more land. This study demonstrates that mealworms should be considered a more sustainable source of edible protein.     

A lipoxygenase with linoleate diol synthase activity from Nostoc sp. PCC 7120

Bax, a pro-apoptotic Bcl-2 family protein, translocates to mitochondria during apoptosis, where it causes MOMP (mitochondrial outer membrane permeabilization). MOMP releases pro-apoptotic factors, such as cytochrome c and SMAC (second mitochondrial activator of caspases)/Diablo, into the cytosol where they activate caspases. It is often inferred that Bax activation occurs in a single step, a conformational change in the protein causing its translocation and oligomerization into high-molecular-mass membrane pores. However, a number of studies have shown that Bax translocation to mitochondria does not necessarily induce MOMP. Indeed, Bax translocation can occur several hours prior to release of cytochrome c, indicating that its regulation may be a complex series of events, some of which occur following its association with mitochondria. In the present study, we have examined endogenous Bax in epithelial cells undergoing anoikis, a physiologically relevant form of apoptosis that occurs when normal cells lose contact with the ECM (extracellular matrix). Using BN-PAGE (blue native PAGE), we show that Bax forms a 200 kDa complex before caspase activation. Furthermore, Bax in this 200 kDa complex is not in the active conformation, as determined by exposure of N-terminal epitopes. These results indicate that Bax oligomerization is an event that must be interpreted differently from the currently held view that it represents the apoptotic pore.