Structural elucidation of hydroxy fatty acids by photodissociation mass spectrometry with photolabile derivatives

© 2020 John Wiley & Sons, Ltd. Rationale: Eicosanoids are short-lived bio-responsive lipids produced locally from oxidation of polyunsaturated fatty acids (FAs) via a cascade of enzymatic or free radical reactions. Alterations in the composition and concentration of eicosanoids are indicative of inflammation responses and there is strong interest in developing analytical methods for the sensitive and selective detection of these lipids in biological mixtures. Most eicosanoids are hydroxy FAs (HFAs), which present a particular analytical challenge due to the presence of regioisomers arising from differing locations of hydroxylation and unsaturation within their structures. Methods: In this study, the recently developed derivatization reagent 1-(3-(aminomethyl)-4-iodophenyl)pyridin-1-ium (4-I-AMPP+) was applied to a representative set of HFAs including bioactive eicosanoids. Photodissociation (PD) mass spectra obtained at 266 nm of 4-I-AMPP+-modified HFAs exhibit abundant product ions arising from photolysis of the aryl–iodide bond within the derivative with subsequent migration of the radical to the hydroxyl group promoting fragmentation of the FA chain and facilitating structural assignment. Results: Representative polyunsaturated HFAs (from the hydroxyeicosatetraenoic acid and hydroxyeicosapentaenoic acid families) were derivatized with 4-I-AMPP+ and subjected to a reversed-phase liquid chromatography workflow that afforded chromatographic resolution of isomers in conjunction with structurally diagnostic PD mass spectra. Conclusions: PD of these complex HFAs was found to be sensitive to the locations of hydroxyl groups and carbon–carbon double bonds, which are structural properties strongly associated with the biosynthetic origins of these lipid mediators

SEIPIN Regulates Lipid Droplet Expansion and Adipocyte Development by Modulating the Activity of Glycerol-3-phosphate Acyltransferase

Berardinelli-Seip congenital lipodystrophy 2 (BSCL2) is caused by loss-of-function mutations in SEIPIN, a protein implicated in both adipogenesis and lipid droplet expansion but whose molecular function remains obscure. Here, we identify physical and functional interactions between SEIPIN and microsomal isoforms of glycerol-3-phosphate acyltransferase (GPAT) in multiple organisms. Compared to controls, GPAT activity was elevated in SEIPIN-deficient cells and tissues and GPAT kinetic values were altered. Increased GPAT activity appears to underpin the block in adipogenesis and abnormal lipid droplet morphology associated with SEIPIN loss. Overexpression of Gpat3 blocked adipogenesis, and Gpat3 knockdown in SEIPIN-deficient preadipocytes partially restored differentiation. GPAT overexpression in yeast, preadipocytes, and fly salivary glands also formed supersized lipid droplets. Finally, pharmacological inhibition of GPAT in Seipin-/- mouse preadipocytes partially restored adipogenesis. These data identify SEIPIN as an evolutionarily conserved regulator of microsomal GPAT and suggest that GPAT inhibitors might be useful for the treatment of human BSCL2 patients

Biochemical Properties of Highly Neuroinvasive Prion Strains

Infectious prions propagate from peripheral entry sites into the central nervous system (CNS), where they cause progressive neurodegeneration that ultimately leads to death. Yet the pathogenesis of prion disease can vary dramatically depending on the strain, or conformational variant of the aberrantly folded and aggregated protein, PrPSc. Although most prion strains invade the CNS, some prion strains cannot gain entry and do not cause clinical signs of disease. The conformational basis for this remarkable variation in the pathogenesis among strains is unclear. Using mouse-adapted prion strains, here we show that highly neuroinvasive prion strains primarily form diffuse aggregates in brain and are noncongophilic, conformationally unstable in denaturing conditions, and lead to rapidly lethal disease. These neuroinvasive strains efficiently generate PrPSc over short incubation periods. In contrast, the weakly neuroinvasive prion strains form large fibrillary plaques and are stable, congophilic, and inefficiently generate PrPSc over long incubation periods. Overall, these results indicate that the most neuroinvasive prion strains are also the least stable, and support the concept that the efficient replication and unstable nature of the most rapidly converting prions may be a feature linked to their efficient spread into the CNS

THE RELATIONSHIPS BETWEEN POOR HEALTH, COPING STYLES, AND HEALTH PRACTICES: A TEST OF SEVERAL POSSIBLE MODERATORS

This study sought to examine the relationship between poor health and coping styles and the relationship between poor health and health practices. Another goal of this study was to observe if variables such as depression, religiosity, and locus of control might serve as moderators of these relationships. The participants and data used in this study were from the Eugene-Springfield Community Sample. The materials used included the Health Practices Questionnaire (HPQ), the Personal Attribute Survey (PAS), the Comprehensive Health Survey (CHS), and the Experimental Personality Survey (EPS). Structural equation modeling was used to analyze the data. The results revealed that poor health was positively associated with distraction coping, instrumental coping, emotional-preoccupation coping, and health practices. Furthermore, depression was positively associated with emotional-preoccupation coping; religiosity was positively associated with distraction coping, palliative coping, and instrumental coping as well as health practices; and locus of control was negatively associated with emotional-preoccupation coping. No moderating effect of depression, religiosity, or locus of control was found on the relationships between poor health, coping styles, and health practices