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In humans, dietary polyunsaturated fatty acids (PUFAs) are involved in therapeutic processes such as prevention and treatment of cardiovascular diseases, neuropsychiatric disorders, and dementia. We examined the physiology, PUFA accumulation and glycerol lipid biosynthesis in the marine microalga Nannochloropsis salina in response to constant suboptimal temperature (<20 °C). As expected, N. salina exhibited significantly reduced growth rate and photosynthetic activity compared to optimal cultivation temperature. Total fatty acid contents were not significantly elevated at reduced temperatures. Cultures grown at 5 °C had the highest quantity of eicosapentanoic acid (EPA) (C20:5n3) and the lowest growth rate. Additionally, we monitored broadband lipid composition to model the occurrence of metabolic alteration and remodeling for various lipid pools. We focused on triacylglycerol (TAG) with elevated PUFA content. TAGs with EPA at all three acyl positions were higher at a cultivation temperature of 15 °C. Furthermore, monogalactosyldiacylglycerol and digalactosyldiacylglycerol, which are polar lipids associated with chloroplast membranes, decreased with reduced cultivation temperatures. Moreover, gene expression analysis of key genes involved in Kennedy pathway for de novo TAG biosynthesis revealed bimodal variations in transcript level amongst the temperature treatments. Collectively, these results show that Nannochloropsis salina is a promising source of PUFA containing lipids.
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The Role of p38 MAPK in Triacylglycerol Accumulation during Apoptosis
Abstract Lipids are emerging as key regulators of apoptosis. Specific lipid species are associated with apoptosis with important functional roles, but the understanding of the regulation of these lipid species is still limited. It has been previously shown by our laboratory that polyunsaturated triacylglycerols accumulate and get stored within lipid droplets during apoptosis via activated glycerolipid biosynthesis. In this work, the biochemical mechanisms that result in the activation of glycerolipid biosynthesis and, consequently, triacylglycerol and lipid droplet accumulation during apoptosis are investigated. The transcriptomes of control and apoptotic HCT‐116 cells are compared and gene enrichment analysis revealed the upregulation of p38 mitogen‐activated protein kinase (MAPK). It is shown that p38 MAPK regulates triacylglycerol biosynthesis through diacylglycerol acyltransferase1 during apoptosis. Perilipin 2 and cytosolic phospholipase A2delta are also shown to be involved in lipid droplet and polyunsaturated triacylglycerol accumulation in this process. Overall, the results provide new insights into the upregulation of glycerolipid synthesis during apoptosis.
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- Award ID(s):
- 1817468
- PAR ID:
- 10461424
- Publisher / Repository:
- Wiley Blackwell (John Wiley & Sons)
- Date Published:
- Journal Name:
- PROTEOMICS
- Volume:
- 19
- Issue:
- 13
- ISSN:
- 1615-9853
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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