Inhibition of Neuronal Apoptosis by Docosahexaenoic Acid (22:6n-3)

Enrichment of Neuro 2A cells with docosahexaenoic acid (22:6n-3) decreased apoptotic cell death induced by serum starvation as evidenced by the reduced DNA fragmentation and caspase-3 activity. The protective effect of 22:6n-3 became evident only after at least 24 h of enrichment before serum starvation and was potentiated as a function of the enrichment period. During enrichment 22:6n-3 incorporated into phosphatidylserine (PS) steadily, resulting in a significant increase in the total PS content. Similar treatment with oleic acid (18:1n-9) neither altered PS content nor resulted in protective effect. Hindering PS accumulation by enriching cells in a serine-free medium diminished the protective effect of 22:6n-3. Membrane translocation of Raf-1 was significantly enhanced by 22:6n-3 enrichment in Neuro 2A cells. Consistently, in vitrobiomolecular interaction between PS/phosphatidylethanolamine /phosphatidylcholine liposomes, and Raf-1 increased in a PS concentration-dependent manner. Collectively, enrichment of neuronal cells with 22:6n-3 increases the PS content and Raf-1 translocation, down-regulates caspase-3 activity, and prevents apoptotic cell death. Both the antiapoptotic effect of 22:6n-3 and Raf-1 translocation are sensitive to 22:6n-3 enrichment-induced PS accumulation, strongly suggesting that the protective effect of 22:6n-3 may be mediated at least in part through the promoted accumulation of PS in neuronal membranes. Enrichment of Neuro 2A cells with docosahexaenoic acid (22:6n-3) decreased apoptotic cell death induced by serum starvation as evidenced by the reduced DNA fragmentation and caspase-3 activity. The protective effect of 22:6n-3 became evident only after at least 24 h of enrichment before serum starvation and was potentiated as a function of the enrichment period. During enrichment 22:6n-3 incorporated into phosphatidylserine (PS) steadily, resulting in a significant increase in the total PS content. Similar treatment with oleic acid (18:1n-9) neither altered PS content nor resulted in protective effect. Hindering PS accumulation by enriching cells in a serine-free medium diminished the protective effect of 22:6n-3. Membrane translocation of Raf-1 was significantly enhanced by 22:6n-3 enrichment in Neuro 2A cells. Consistently, in vitrobiomolecular interaction between PS/phosphatidylethanolamine /phosphatidylcholine liposomes, and Raf-1 increased in a PS concentration-dependent manner. Collectively, enrichment of neuronal cells with 22:6n-3 increases the PS content and Raf-1 translocation, down-regulates caspase-3 activity, and prevents apoptotic cell death. Both the antiapoptotic effect of 22:6n-3 and Raf-1 translocation are sensitive to 22:6n-3 enrichment-induced PS accumulation, strongly suggesting that the protective effect of 22:6n-3 may be mediated at least in part through the promoted accumulation of PS in neuronal membranes. Dulbecco's modified Eagle's medium phosphate-buffered saline docosahexaenoic acid arachidonic acid oleic acid phosphatidylserine phosphatidylethanolamine phosphatidylcholine sphingomyelin liquid chromatography/mass spectrometry phospholipase A2 polymerase chain reaction polyacrylamide gel electrophoresis brain derived neurotrophic factor Ca2+-independent phospholipase A2 Mammalian brain is rich in long chain polyunsaturated fatty acids. Docosahexaenoic acid (22:6n-3), the major n-3 fatty acid found in brain, is highly enriched in neuronal cells (1Salem Jr., N. Omega-3 Fatty Acids: Molecular and Biochemical Aspects. Alan R. Liss, New York1989: 109-228Google Scholar). Growing evidences support the essential role of 22:6n-3 in neuronal function. In animal models n-3 fatty acid deficiency caused memory deficit (2Gamoh S. Hashimoto M. Sugioka K. Shahdat Hossain M. Hata N. Misawa Y. Masumura S. Neuroscience. 1999; 93: 237-241Crossref PubMed Scopus (253) Google Scholar), learning disability (3Yoshida S. Yasuda A. Kawazato H. Sakai K. Shimada T. Takeshita M. Yuasa S. Kobayashi T. Watanabe S. Okuyama H. J. Neurochem. 1997; 68: 1261-1268Crossref PubMed Scopus (101) Google Scholar, 4Carrie I. Clement M. De Javel D. Frances H. Bourre J.M. Neurosci. Lett. 1999; 266: 69-72Crossref PubMed Scopus (33) Google Scholar), and visual acuity loss (5Neuringe M. Am. J. Clin. Nutr. 2000; 71 (suppl.): 256-267Crossref Google Scholar). In humans, various neurological disease states have been shown to be associated with a deficient 22:6n-3 status, implying the influence of this fatty acid in neuronal function (6Hoffman D.R. Birch D.G. World Rev. Nutr. Diet. 1998; 83: 52-60Crossref PubMed Google Scholar, 7Martinez M. Brain Res. 1992; 583: 171-182Crossref PubMed Scopus (147) Google Scholar). In the case of preterm infants with underdeveloped brains, the inclusion of 22:6n-3 fatty acid in infant formula has been shown to improve visual attention (8Birch E.E. Hoffman D.R. Uauy R. Birch D.G. Prestidge C. Pediatr. Res. 1998; 44: 201-209Crossref PubMed Scopus (404) Google Scholar). More recently, it has been shown that 22:6n-3 is required for the survival of rat retinal photoreceptors (9Rotstein N.P. Aveldano M.I. Barrantes F.J. Roccamo A.M. Politi L.E. J. Neurochem. 1997; 69: 504-513Crossref PubMed Scopus (108) Google Scholar) and exerts a protective effect on apoptosis of retinal photoreceptors during development (10Rotstein N.P. Aveldano M.I. Barrantes F.J. Politi L.E. J. Neurochem. 1996; 66: 1851-1859Crossref PubMed Scopus (101) Google Scholar). Neuronal apoptosis normally occurs during the development and maturation period (11Sastry P.S. Rao K.S. J. Neurochem. 2000; 74: 1-20Crossref PubMed Scopus (394) Google Scholar, 12Homma S. Yaginuma H. Oppenheim R.W. J. Comp. Neurol. 1994; 345: 377-395Crossref PubMed Scopus (117) Google Scholar, 13Oppenheim R.W. Schwartz L.M. Shatz C.J. J. Neurobiol. 1992; 23: 1111-1351Crossref PubMed Scopus (37) Google Scholar). However, it has been shown that various neurodegenerative conditions are also associated with apoptotic neuronal cell death (14Thompson C.G. Science. 1995; 267: 1456-1460Crossref PubMed Scopus (6162) Google Scholar, 15Portera-Cailliau C. Hedreen J.C. Price D.L. Koliatsos V.E. J. Neurosci. 1995; 15: 3775-3787Crossref PubMed Google Scholar, 16Yamatsuji T. Okamoto T. Komatsuzaki K. Komatsuzaki K. Takeda S. Fukumoto H. Iwatsubo T. Suzuki N. Asami-Odaka A. Ireland S. Kinane T.B. Giambarella U. Nishimoto I. Science. 1996; 272: 1349-1352Crossref PubMed Scopus (216) Google Scholar). Neuronal cell survival is critically dependent on the supply of trophic factors, which influences downstream signaling pathways (17Barde Y.A. Neuron. 1989; 2: 1525-1534Abstract Full Text PDF PubMed Scopus (1442) Google Scholar). For example, in many cells phosphatidylinositol 3-kinase-dependent Akt serine/threonine kinase transduces a survival signal through phosphorylating proapoptotic protein BAD, which in turn associates with 14-3-3, preventing the interaction of BAD with Bcl-2 and Bcl-XL (18Zha J. Harda H. Yang E. Jockel J. Korsmeyer S.J. Cell. 1996; 87: 619-628Abstract Full Text Full Text PDF PubMed Scopus (2233) Google Scholar, 19Datta S.R. Dudek H. Tao X. Masters S. Fu H. Gotoh Y. Greenberg M.E. Cell. 1997; 91: 231-241Abstract Full Text Full Text PDF PubMed Scopus (4895) Google Scholar, 20Dudek H. Datta S.R. Franke T. Birnbaum M.J. Yao R. Cooper G.M. Segal R.A. Kaplan D. Greenberg M.E. Science. 1997; 275: 661-665Crossref PubMed Scopus (2212) Google Scholar). Deprivation of trophic factors inhibits phosphatidylinositol 3-kinase/Akt and subsequently BAD phosphorylation, which enables binding of BAD to Bcl-XL, resulting in mitochondrial damage. Subsequent release of cytochromec activates caspases, ultimately leading to apoptotic cell death (21Green D. Reed J.C. Science. 1998; 281: 1309-1312Crossref PubMed Google Scholar). Growing evidence indicates that Raf-1 activation, which is known to be essential for transducing signals of many growth factors, can play an important role in the regulation of apoptotic processes (22Hoyle P.E. Moye P.W. Steelman L.S. Blalock W.L. Franklin R.A. Pearce M. Cherwinski H. Bosch E. McMahon M. McCubrey J.A. Leukemia (Baltimore ). 2000; 14: 642-656Crossref PubMed Scopus (87) Google Scholar, 23Neshat M.S. Raitano A.B. Wang H.G. Reed J.C. Sawyers C.L. Mol. Cell. Biol. 2000; 20: 1179-1186Crossref PubMed Scopus (162) Google Scholar, 24Salomoni P. Wasik M.A. Riedel R.F. Reiss K. Choi J.K. Skorski T. Calabretta J. 1998; PubMed Scopus (101) Google Scholar). of Raf-1 kinase has been shown to apoptosis in cells (22Hoyle P.E. Moye P.W. Steelman L.S. Blalock W.L. Franklin R.A. Pearce M. Cherwinski H. Bosch E. McMahon M. McCubrey J.A. Leukemia (Baltimore ). 2000; 14: 642-656Crossref PubMed Scopus (87) Google Scholar). has been also shown that of Raf-1 in cells which cells apoptosis induced by growth factor can apoptosis M.S. Raitano A.B. Wang H.G. Reed J.C. Sawyers C.L. Mol. Cell. Biol. 2000; 20: 1179-1186Crossref PubMed Scopus (162) Google Scholar). In of mitochondrial Raf-1 has been shown to antiapoptotic of a P. Wasik M.A. Riedel R.F. Reiss K. Choi J.K. Skorski T. Calabretta J. 1998; PubMed Scopus (101) Google Scholar). it has been that of mitochondrial Raf-1 is in the antiapoptotic effect of Akt M. M. P. A. Reiss K. R. Calabretta Skorski T. Res. 1999; Google Scholar). of Raf-1 is and translocation of Raf-1 to the and are to be important for D. K. M. Science. 1994; PubMed Scopus Google Scholar, S.J. C.J. 1994; PubMed Scopus Google Scholar, H. D. S. M.S. 1998; PubMed Scopus Google Scholar, Biol. 1997; PubMed Scopus Google Scholar). has been shown that Raf-1 kinase binding for and acid S. J.C. J. Biol. 1996; Full Text Full Text PDF PubMed Scopus Google Scholar), and the of Raf-1 may be dependent on the of is the major in cell and is enriched with 22:6n-3 fatty acid (1Salem Jr., N. Omega-3 Fatty Acids: Molecular and Biochemical Aspects. Alan R. Liss, New York1989: 109-228Google Scholar). have that which is in neuronal the accumulation of phosphatidylserine in cell C. Jr., N. J. Neurochem. 1998; PubMed Scopus Google Scholar, J. 2000; PubMed Scopus Google Scholar). In the the of 22:6n-3 by effect on apoptotic trophic factor in to to phosphatidylserine found that enrichment of neuronal cells with 22:6n-3 increased the accumulation of PS and the of caspase-3 activity, and apoptotic cell death protective was sensitive to the of PS accumulation, suggesting that the antiapoptotic effect of 22:6n-3 may be mediated at least in part through the enhanced PS accumulation in neuronal membranes. Dulbecco's modified Eagle's medium and for Raf-1 and caspase-3 and DNA was Molecular was gel Fatty acid and and cells in medium with serum and serum in a Neuro 2A cells in with serum in a of and at The medium was and cells For DNA fragmentation by cells on at a of and For DNA cells in of medium in For of cells to fatty fatty to serum and to cells in medium during serum the effect of fatty acid Neuro 2A cells with fatty for 24 h and to serum Fatty acid in to serum in the of and in the that of fatty and serum became and during the enrichment fatty The DNA fragmentation by was as in New Scholar). of Neuro 2A cells with of for 24 cells with medium to and in the medium for cells enriched with fatty before serum was 24 h before the of serum cells and at for at of the was with the of during apoptosis induced by serum The cells in a in The DNA and the DNA by at for at The DNA was the with The in and to liquid The DNA fragmentation is as the of DNA was Neuro 2A cells by an apoptotic DNA Molecular to the after h of serum as the cells by in of and with of and at for of and the DNA was by a through a to a The was on and and DNA was The DNA was in and with and in to of total DNA was on gel in in at and h of serum the medium was at to which subsequently in of The cells to the on the with of for and and of in was for at least cells by with a Neuro 2A cells with and the was in of that and The protein was by acid PubMed Scopus Google Scholar). of protein a gel and at a of the gel to a at for and the with and by enhanced was a to the cell at for at and protein in the resulting by with for h at and the at was was Neuro 2A cells to the and of was with and for The was with of for at and by of of in of reaction of of and of of The was in a at for a by a at and a the was the after was by with of for at of of reaction Molecular was with of an at and a downstream at was as for at and at for at and for at of was as a a of was by after of the was on gel and for h at Neuro 2A cells on at a of in of the of was in of serum and E. The of the fatty acid was to fatty acids. and h of the medium was and the cells with medium serum in and to the of and J. PubMed Scopus Google Scholar). The and in and for The of the with of and on the and was and to liquid as Brain Res. 1997; PubMed Scopus Google Scholar). cells enriched with and as by liquid chromatography/mass spectrometry as C. Jr., N. J. Neurochem. 1998; PubMed Scopus Google Scholar, J. 2000; PubMed Scopus Google Scholar, Wang 1994; Scopus Google Scholar). of of phosphatidylcholine phosphatidylethanolamine and phosphatidylserine (PS) by the of and PS in in of in on and only a The before to an the with an of acid in with a a and through a on a to was on a as by the and serum was to the for a total of the was the was with The was Raf-1 was on the cell cells The cell was in cell was as the and was this The cell of Raf-1 on the and Raf-1 interaction at a The into the and the with and Raf-1 was of the was in a was into the by an of the to with the was for The protein was by gel electrophoresis by Raf-1 to the of the enrichment of Neuro 2A cells with fatty for cells and in at The cells with of in of for at Membrane and as S. J.C. J. Biol. 1996; Full Text Full Text PDF PubMed Scopus Google Scholar), with after the cells with in of and and by in of and cells and by at for at The was at for at The was and the was by in of and The protein content was by the protein The Raf-1 protein and was by gel electrophoresis and was the of Neuro 2A cells the conditions for h induced apoptotic cell as by DNA Neuro 2A cells of cells with during the serum period decreased the DNA fragmentation induced by serum 22:6n-3 was at a fatty and DNA fragmentation increased The protective effect to be have significant effect as was the case with 22:6n-3. 22:6n-3 fatty acid as in neuronal accumulation of this fatty acid in may play an important role the fatty acid Neuro 2A cells enriched with and the DNA fragmentation induced by serum starvation was the case with of 22:6n-3 during serum starvation Neuro 2A cells enriched with 22:6n-3 for 24 h before serum starvation DNA fragmentation in with the cells enriched with Enrichment of cells with 22:6n-3 for h as was by DNA was that the of the of DNA fragmentation induced by serum starvation on the cell conditions to in serum medium However, it was that the protective effect of 22:6n-3 was as the cells enriched for a period to The cells enriched with also DNA fragmentation the protective effect was sensitive to the of serum starvation as shown in The protective effect of during the conditions was the cells of serum for 22:6n-3 with to h of serum Similar for the of a of that has been shown to apoptosis in cells. Neuro 2A cells enriched with various fatty for h and to the medium for to during which period caspase-3 was the increase of caspase-3 as a function of the starvation with the of cells enriched with 22:6n-3. 24 h of serum and cells caspase-3 in to cells. serum the protective effect of was and only cells caspase-3 at a to serum Neuro 2A cells a DNA on an gel after serum the of apoptotic cell death. Neuro 2A cells required at least h of serum starvation for DNA in is the DNA after the cells enriched with fatty for h and subsequently of serum for In with the shown in and DNA was significantly reduced after enrichment with fatty as the of also as in cells and cells apoptotic cell death. enrichment with 22:6n-3 for h before serum the cells with the treatment with the to the cells. strongly that the effect of fatty acid enrichment may be for of fatty acid enrichment on DNA fragmentation by Neuro 2A cells enriched with various fatty for h and to serum starvation for by with are by in the of DNA fragmentation was by in cells was The with are significantly to the protective effect of 22:6n-3 after a enrichment the of this fatty acid was in to protective effect. shown in which was incorporated into was to and was to cells for was into and in the of and the major and was and The fatty acid of 24 was significantly enriched in and PS in to the and PS only and of the enrichment for an 24 h significantly increased the of in PS in to be at the of the of the was found in the by that the PS content of cells also increased during h of the enrichment period the with 22:6n-3. The increase was to the which to of protein in In cells significant in the PS content during the enrichment period. cells a significantly total PS of in with that of cells and of at h of The protective effect of 22:6n-3 on DNA fragmentation induced by serum starvation was potentiated as the cells enriched for a period of and this increase the PS accumulation during the of In PS is by the reaction J. PubMed Scopus Google Scholar). to the PS accumulation, Neuro 2A cells enriched with fatty in a serine-free medium before serum and caspase-3 was in to PS accumulation the the PS accumulation enhanced by increase in the PS content was significantly in with the cells enriched in the medium the protective effect of 22:6n-3 on caspase-3 activation, as shown by was in the cells in the serine-free the that PS accumulation has a role in the protective effect of 22:6n-3. the caspase-3 nor the PS content in cells was significantly by the serine-free Fatty acid enrichment decreased The to be of protein conditions and of protein conditions for The content be to of a it was to in various cell on the of the in The significantly after various fatty acid that at a Raf-1 kinase has been to be in cell survival M.S. Raitano A.B. Wang H.G. Reed J.C. Sawyers C.L. Mol. Cell. Biol. 2000; 20: 1179-1186Crossref PubMed Scopus (162) Google Scholar, 24Salomoni P. Wasik M.A. Riedel R.F. Reiss K. Choi J.K. Skorski T. Calabretta J. 1998; PubMed Scopus (101) Google Scholar, M. M. P. A. Reiss K. R. Calabretta Skorski T. Res. 1999; Google Scholar). has been shown that translocation is required for the of Raf-1 D. K. M. Science. 1994; PubMed Scopus Google Scholar, S.J. C.J. 1994; PubMed Scopus Google Scholar) and the with PS an important role in this S. J.C. J. Biol. 1996; Full Text Full Text PDF PubMed Scopus Google Scholar). of PS accumulation by 22:6n-3 may influence the translocation of Neuro 2A enriched with 22:6n-3 for with for and the translocation of Raf-1 was in with cells. shown in Raf-1 to in to enriched with 22:6n-3 significantly of Raf-1 in to cells and was that the of total Raf-1 kinase was in as shown for protein and in that 22:6n-3 enrichment only the translocation of Raf-1 also in Neuro 2A cells. the enrichment of Neuro 2A cells significantly PS accumulation as as translocation of the enhanced PS in cell a role in the promoted translocation of the interaction of this protein with with of PS was in interaction a Raf-1 protein was and the binding of to the Raf-1 was by the in the signal resulting the of the on the to the binding M. 1992; PubMed Scopus Google Scholar). The and PS and in the of PS with the interaction was as the PS the 22:6n-3 and the of fatty acid also In this the role docosahexaenoic acid (22:6n-3) in neuronal apoptosis induced by serum that 22:6n-3 PS accumulation and neuronal cells apoptotic cell death as a The between PS accumulation and the protective effect by 22:6n-3 strongly that the antiapoptotic effect of 22:6n-3 enrichment may be mediated at least in part through the promoted accumulation of PS in neuronal membranes. also that of PS accumulation by 22:6n-3 the translocation of Raf-1 to membranes. 22:6n-3 was to medium during the serum starvation the protective effect was In the of during the enrichment period diminished the protective effect of suggesting that as the fatty acid as a may protective effect. The of caspase-3 activity, DNA fragmentation by DNA as as caspase-3 to the the effect of 22:6n-3 after In of apoptosis by 22:6n-3 only after 24 h of enrichment has been E. M. M. Y. 1998; PubMed Scopus Google Scholar), suggesting that 22:6n-3 as a may be for the effect. with the of the of altered by 22:6n-3 during the enrichment period be the of Raf-1 in cells. In a is by 22:6n-3 enrichment the PS accumulation to be an important factor in has been that the of 22:6n-3 in brain occurs in this fatty acid is Brain Res. 1997; PubMed Scopus Google Scholar, E. S. J. Neurochem. PubMed Scopus Google Scholar), suggesting that of the of may 22:6n-3 fatty acid to neuronal cells for The 22:6n-3 to in neuronal this fatty acid has been shown to be to the in neuronal cells M. H. Biol. 1999; PubMed Scopus Google Scholar, 1999; (suppl.): Google Scholar), in to release in to various A. M. J. PubMed Scopus Google Scholar). in neuronal PS is enriched with which of the total fatty acid in PS R. Neurochem. Res. PubMed Scopus Google Scholar). the PS content has been shown to be in neuronal cells in to cells J. R. Jr., N. 2000; PubMed Scopus Google Scholar, and of Scholar). that neuronal cells may and 22:6n-3 in to of PS in neuronal membranes. The also that 22:6n-3 is a of PS accumulation in Neuro 2A cells. Deprivation of the diminished the effect of 22:6n-3 on PS accumulation, that PS is the major for the enhanced PS The between the antiapoptotic effect of 22:6n-3 enrichment and PS accumulation was evident the protective effect to the PS content by the enrichment with various fatty by enrichment and by the supply for the PS In the PS content the of the protective strongly suggesting that 22:6n-3 as a of PS accumulation may play a role in preventing neuronal apoptosis induced by serum The of as C. Jr., N. J. Neurochem. 1998; PubMed Scopus Google Scholar, Wang 1994; Scopus Google Scholar) that Neuro 2A cells enriched with 22:6n-3 in serine-free that has been in J. T. S. Y. J. Biol. 1998; Full Text Full Text PDF PubMed Scopus Google Scholar). of in neuronal apoptosis has been R. J. Neurosci. Res. 2000; PubMed Scopus Google Scholar). The of in serine-free the of that Jr., PubMed Scopus (394) Google Scholar). However, neither fatty acid enrichment nor suggesting that may be regulation in of this signaling in was influence of 22:6n-3 enrichment on of the status, was required for the antiapoptotic effect of 22:6n-3 strongly suggesting to be highly has been that by the of the of various signaling as protein kinase and and in to R. C. J. 1994; Google Scholar). of which was with fatty acid in this may be to the fatty acid the protective effect of also increased the PS accumulation after h of enrichment of was to apoptosis during long serum The loss of the protective effect in cells after serum starvation that signaling pathways may also be it has been that of during apoptosis fatty acid release M. K. A. M. I. J. Biol. 2000; 275: Full Text Full Text PDF PubMed Scopus Google Scholar). has been that and that release can be promoted by M. K. A. M. I. J. Biol. 2000; 275: Full Text Full Text PDF PubMed Scopus Google Scholar). it is that the neuronal enriched with may be to the increased during serum that fatty acid may the pathways sensitive to may during the apoptotic and may the protective effect. the of neuronal cell and apoptosis are in this on signaling pathways derived the protein kinase protein kinase as as pathways as the of phosphatidylinositol 3-kinase/Akt D.R. Brain Res. 1998; PubMed Google Scholar). has been that PS is in various signaling pathways protein kinase and Raf-1 kinase S. J.C. J. Biol. 1996; Full Text Full Text PDF PubMed Scopus Google Scholar, M. 1998; PubMed Scopus Google Scholar, D.G. Jr., J.K. S. Cooper J.A. J. Biol. 1998; Full Text Full Text PDF PubMed Scopus Google Scholar). of Raf-1 kinase to cell an important in growth factor has been shown to be by and PS S. J.C. J. Biol. 1996; Full Text Full Text PDF PubMed Scopus Google Scholar, S. K. Science. 1999; PubMed Scopus Google Scholar). has been also shown that Raf-1 with PS through the PS binding S. J.C. J. Biol. 1996; Full Text Full Text PDF PubMed Scopus Google the effect of PS on interaction has been The of Raf-1 in the in may be with the to binding to in the interaction the PS in the interaction of Raf-1 and that binding to Raf-1 may significantly interaction with The in of PS the enhanced translocation of Raf-1 in cells PS increased significantly the role of in evidence indicates the of interaction with the phosphatidylinositol 3-kinase/Akt for cell survival in an D. K. M. Science. 1994; PubMed Scopus Google Scholar, S.J. C.J. 1994; PubMed Scopus Google Scholar, H. D. S. M.S. 1998; PubMed Scopus Google Scholar) S. K. Science. 1999; PubMed Scopus Google Scholar, C. S. R. K. K. Science. 1999; PubMed Scopus Google Scholar). in signaling pathways the enhanced translocation of Raf-1 by 22:6n-3 enrichment to the survival signal the be In enrichment of neuronal cells with 22:6n-3 increases the PS content and Raf-1 translocation, down-regulates caspase-3 activity, and prevents apoptotic cell death. The between the of protective effect and the of PS accumulation as as the Raf-1 translocation enhanced by 22:6n-3 enrichment strongly that the protective effect of 22:6n-3 may be mediated at least in part through the promoted accumulation of PS in neuronal membranes. that 22:6n-3 as a of the PS may be an important the for 22:6n-3 fatty acid in the neuronal and for in DNA fragmentation and