Biochemical and Biophysical Research Communications
Differential incorporation of docosahexaenoic acid into distinct cholesterol-rich membrane raft domains
Section snippets
Materials and methods
Materials. Tissue culture media and supplements were purchased from Invitrogen (Paisley, UK). All protease inhibitors were obtained from Calbiochem (Nottingham, UK) and the Lubrol WX was from Serva (Oxford, UK). The claudin and occludin antibodies were purchased from Zymed (San Francisco, USA) and the src antibody from Upstate (Chandler’s Ford, UK) whereas the horseradish peroxidase conjugated secondary antibodies were from Bio-Rad (Hemel Hempstead, UK). All other reagents were obtained from
DHA is incorporated into Caco-2 cell membranes
To establish that feeding the Caco-2 cell monolayers DHA did result in the incorporation of the PUFA into cell membrane lipids, the fatty acid composition of total cell membranes was determined 4 and 8 days after the introduction of DHA (100 μM) (Table 1). DHA produced significant alterations in the fatty acid profile of the cell membranes. By day 8, the amount of DHA present in the membrane lipids had increased nearly tenfold and was accompanied by a compensatory decrease in mainly oleic acid
Discussion
One of the primary ways omega-3 PUFAs, such as EPA and DHA, influence cell function is through modulating the lipid and protein composition, and therefore the function, of membrane rafts. This phenomenon and has been documented in a number of tissues, including the intestine, [4], [5], [14], [15], [16], [17]. EPA and DHA both increase the permeability of Caco-2 cell monolayers [7], [8] by “loosening” the epithelial TJs. Currently the exact mechanism whereby omega-3s influence TJ integrity is
Acknowledgments
This work was supported by a project grant awarded by the Biotechnology and Biological Sciences Research Council, UK.
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Cited by (21)
EPA and DHA differentially modulate membrane elasticity in the presence of cholesterol
2021, Biophysical JournalCitation Excerpt :We then investigated how FFA inclusion affected the Kapp of phospholipid membranes when they contained higher levels of cholesterol, which should form a greater amount of cholesterol-rich, crystalline nanodomains. Previous work by Mason et al. using x-ray diffraction analysis demonstrated that EPA and DHA can have distinct effects on cholesterol nanodomains; whereas EPA enhances cholesterol mixing and disrupts domains by integrating into both liquid-ordered and liquid-disordered domains, DHA increases the size and stability of membrane domains because of its exclusion from ordered domains (11,13,18,53,56–59). Yet, we were unsure of how these structural changes would affect the bulk membrane property, Kapp.
Pathways of polyunsaturated fatty acid utilization: Implications for brain function in neuropsychiatric health and disease
2015, Brain ResearchCitation Excerpt :This has implications for cell membrane lipid matrix properties, formerly referred to as ‘fluidity’ (Shinitzky and Barenholz, 1978), but more recently described in terms of ‘lipid rafts’ or ‘membrane microdomains’, dynamic membrane aggregations of specific lipid composition that promote interactions between membrane-bound proteins by bringing them into physical proximity (Pike, 2006; Yaqoob and Shaikh, 2010). The highly flexible n-3 PUFAs incorporate directly into membranes and thereby promote the partitioning of the more rigid cholesterol and sphingolipid molecules into lipid rafts (Altenburg and Siddiqui, 2009; Duraisamy et al., 2007; Eldho et al., 2003; Grimm et al., 2011; Huster et al., 1998; Langelier et al., 2010; Rockett et al., 2012; Rogers et al., 2010; Schley et al., 2007; Shaikh et al., 2002, 2003, 2004; Soni et al., 2008; Stillwell et al., 2005; Wassall et al., 2004; Wong et al., 2009; Ye et al., 2010). The nutritionally essential shorter chain PUFAs LA and ALA undergo a series of desaturation and elongation steps (Mayes, 1996) in the endoplasmic reticulum and peroxisomes of the liver to form n-6 (AA) and n-3 (EPA and DHA) LC-PUFAs, respectively (Fig. 1), catalyzed by enzymes that are upregulated in response to experimental deficiency of n-3 PUFAs (Rao et al., 2007).
Down-regulation of lipid raft-associated onco-proteins via cholesterol-dependent lipid raft internalization in docosahexaenoic acid-induced apoptosis
2014, Biochimica et Biophysica Acta - Molecular and Cell Biology of LipidsCitation Excerpt :Recently, reports have shown that n-3 PUFA incorporation into lipid rafts can alter the distribution or function of raft-associated signaling molecules by inducing changes in physical properties [10–13,35–37]. For example, DHA decreases EGFR levels and alters EGFR localization in the plasma membrane [14–16], whereas DHA increases CD95 levels in the lipid rafts and improves the efficacy of chemotherapy [17]. Currently, a detailed understanding of DHA-induced raft modifications responsible for the DHA effect on cell growth inhibition has not yet been achieved.
A role for lipid rafts in the protection afforded by docosahexaenoic acid against ethanol toxicity in primary rat hepatocytes
2013, Food and Chemical ToxicologyCitation Excerpt :Indeed, DHA exposure of hepatocytes led to its incorporation both in lipid rafts and non-raft regions. Such a DHA incorporation into lipid rafts was also reported in vitro after DHA treatment of Jurkat T lymphocytes (Li et al., 2005), EL4 B lymphocytes (Shaikh et al., 2009), human retinal endothelial cells (Chen et al., 2007), Caco-2 cells (Duraisamy et al., 2007), and in vivo in B lymphocytes of mice treated with fish oil (Rockett et al., 2012). Inaddition, based upon the DHA aversion for cholesterol (Wassal and Stillwell, 2009), one might have expected that DHA incorporation into lipid rafts would drive the cholesterol expulsion from them.
Biophysical and biochemical mechanisms by which dietary N-3 polyunsaturated fatty acids from fish oil disrupt membrane lipid rafts
2012, Journal of Nutritional BiochemistryCitation Excerpt :The intriguing aspect of this work was that proteins localized in DRMs were displaced in response to n-3 PUFA treatment. More recent in vitro and ex vivo measurements in several cell types have verified the basic hypothesis that n-3 PUFAs incorporate directly into DRMs to displace proteins either into or out of these “raft”-like fractions [30–36]. In some cell types, n-3 PUFAs lower the levels of cholesterol and sphingolipids in the DRMs [31].
Displacement of tight junction proteins from detergent-resistant membrane domains by treatment with sodium caprate
2009, European Journal of Pharmaceutical Sciences