Phosphatidylcholine deficiency upregulates enzymes of triacylglycerol metabolism in CHO cells

We studied the regulation of triacylglycerol (TAG) metabolism by phosphatidylcholine (PC) in CHO MT58 cells, which are deficient in PC synthesis because of a temperature-sensitive CTP:phosphocholine cytidylyltransferase. At the permissive growth temperature (34 degrees C), these cells contained 49% less TAG and 30% less PC than wild-type CHO K1 cells. Treatment with dipalmitoylphosphatidylcholine normalized both the PC and TAG levels. Despite low TAG levels, the incorporation of [14C]oleate into TAG was increased in CHO MT58 cells. The in vitro de novo synthesis of TAG and the activity of diacylglycerol acyltransferase were 90% and 34% higher, respectively. Two other key enzyme activities in TAG synthesis, acyl-CoA synthetase and mitochondrial glycerol-3-phosphate acyltransferase (GPAT), increased by 48% and 2-fold, respectively, and mitochondrial GPAT mRNA increased by approximately 4-fold. Additionally, TAG hydrolysis was accelerated in CHO MT58 cells, and in vitro lipolytic activity increased by 68%. These studies suggest that a homeostatic mechanism increases TAG synthesis and recycling in response to PC deficiency. TAG recycling produces diacylglycerol and fatty acids that can be substrates for de novo PC synthesis and for lysophosphatidylcholine (lysoPC) acylation. In CHO MT58 cells, in which de novo PC synthesis is blocked, lysoPC acylation with fatty acid originating from TAG may represent the main pathway for generating PC

An ecological momentary assessment study of mood state and working memory capacity in college students who experience frequent mood fluctuations

Ph.D. University of Hawaii at Manoa 2014.Includes bibliographical references.Manic, hypomanic, and depressed mood states have been shown to be associated with significant impairments in working memory capacity. Previous studies on mood state and working memory capacity have included only participants formally diagnosed with a bipolar disorder. No study has examined this relationship in persons who experience fluctuations in mood state but do not meet diagnostic criteria for a bipolar disorder. Nor have previous studies examined the relationship between mood state and working memory capacity in college students, where working memory capacity may be particularly important to academic performance. In addition, few studies of these variables have been conducted in the participants' daily lives, rather than in laboratory settings. The goal of this study was to examine the relationships between mood state and working memory capacity in the daily lives of college students who experience frequent fluctuations in mood state. Four female and three male participants completed multiple daily mood state ratings and tests of working memory capacity using an ecological momentary assessment task. Significant relationships were observed between concurrent measures of mood state and working memory capacity for three out of seven participants. A significant relationship was also observed between time-lagged measures of mood state and working memory capacity for one out of seven participants. Finally, no relationship was observed between time-lagged measures of working memory capacity and mood state. Inferences regarding mood state and working memory capacity in college students with frequent mood fluctuations and the advantages of utilizing time-series methodology to examine mood states were discussed

Elucidating Mechanisms of Toxicity Using Phenotypic Data from Primary Human Cell Systems—A Chemical Biology Approach for Thrombosis-Related Side Effects

Here we describe a chemical biology approach for elucidating potential toxicity mechanisms for thrombosis-related side effects. This work takes advantage of a large chemical biology data set comprising the effects of known, well-characterized reference agents on the cell surface levels of tissue factor (TF) in a primary human endothelial cell-based model of vascular inflammation, the BioMAP® 3C system. In previous work with the Environmental Protection Agency (EPA) for the ToxCast™ program, aryl hydrocarbon receptor (AhR) agonists and estrogen receptor (ER) antagonists were found to share an usual activity, that of increasing TF levels in this system. Since human exposure to compounds in both chemical classes is associated with increased incidence of thrombosis-related side effects, we expanded this analysis with a large number of well-characterized reference compounds in order to better understand the underlying mechanisms. As a result, mechanisms for increasing (AhR, histamine H1 receptor, histone deacetylase or HDAC, hsp90, nuclear factor kappa B or NFκB, MEK, oncostatin M receptor, Jak kinase, and p38 MAPK) and decreasing (vacuolar ATPase or V-ATPase) and mTOR) TF expression levels were uncovered. These data identify the nutrient, lipid, bacterial, and hypoxia sensing functions of autophagy as potential key regulatory points controlling cell surface TF levels in endothelial cells and support the mechanistic hypothesis that these functions are associated with thrombosis-related side effects in vivo