Studies on Functional Role of Docosahexaenoic acid (DHA) in the Brain
IR@IICB: CSIR-Indian Institute of Chemical Biology, Kolkata
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| Title |
Studies on Functional Role of Docosahexaenoic acid (DHA) in the Brain
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| Creator |
Das, Moitreyi
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| Subject |
Cell Biology & Physiology
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| Description |
Docosahexaenoic acid (DHA), an important ω-3 fatty acid, showed opposite effect in two different types of cells, inducing apoptosis in neoplastic cells but promoting differentiation in normal cells. With a view to understand more about the mechanisms of such divergent action
of DHA, the present study was conceived. Treatment of C6 glioma and SH-SY5Y cell lines, representing the neoplastic cells, with 100 μM DHA for 24 h caused significant increase in apoptosis, as determined by TUNEL staining, whereas primary astrocytes cultures, representing normal healthy cells were unaffected. Employing proteomic approach, we have
identified six proteins which unlike in the astrocytes, were differently altered in the cancer cells upon exposure to DHA, suggesting their putative contribution in causing apoptosis in these cells. Of these, annexin A2, calumenin, pyruvate kinase M2 isoform, 14-3-3ζ were downregulated while aldo keto reductase-1B8 and glutathione–S-transferase P1 subunit showed upregulation by DHA in the cancer cells. Western blot analysis also identified upregulation of PPARα and the MAP kinases, ERK, JNK and p38 as well as increased ROS production selectively in the cell lines. Together, activation of multiple apoptotic pathways in
association with excess ROS and activated MAPKs appear to promote cancer cell death by DHA. Like thyroid hormones (TH), DHA also facilitated astrocytes differentiation in culture, involving a downstream role β-adrenergic receptor (β-AR) system. We explored the detailed signaling mechanisms during the differentiation process induced by TH or DHA. TH, caused an immediate decrease in the specific binding of 125I-pindolol to β2-AR in cell membranes
with a concomitant increase in β2-AR levels in the cytosol, which could be blocked by endocytic inhibitors, suggesting endocytosis of β2-AR. qRT-PCR and western blot analysis
together with knockdown and overexpression experiment demonstrated that β-arrestin-1 is transcriptionally upregulated by TH facilitating increased endocytosis of β2-AR, required for endosomal ERK activation to drive the differentiation process. DHA also promoted β2-AR
internalization and its subsequent down-stream events to induce differentiation of the cells, not by increasing the expression of β-arrestin-1 but by increasing the expression of β2-AR levels.
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| Date |
2016
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| Type |
Thesis
NonPeerReviewed |
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| Format |
application/pdf
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| Identifier |
http://www.eprints.iicb.res.in/2507/1/Moitreyi_Das_Thesis.pdf
Das, Moitreyi (2016) Studies on Functional Role of Docosahexaenoic acid (DHA) in the Brain. PhD thesis, University of Calcutta. |
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| Relation |
http://www.eprints.iicb.res.in/2507/
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