Polyunsaturated fatty acid elongation and desaturation in activated human T-cells: ELOVL5 is the key elongase.

PUFAs are important constituents of membrane glycerophospholipids. However, changes in the capacities to incorporate and metabolize PUFAs when cells enter the cell cycle have not been thoroughly studied. In this study, differences in the incorporation and metabolism of exogenous PUFAs in resting and proliferating primary human T-cells and in the Jurkat cell line were measured. Overall, proliferating T-cells and Jurkat cells had a greater capacity to incorporate and elongate exogenous 18- and 20-carbon PUFAs compared with resting T-cells. Proliferating T-cells and Jurkat cells also showed a greater capacity to desaturate 18-carbon PUFA substrates. Consistent with these observations, a significant increase in the expression of fatty acid desaturase (FADS) 1, FADS2, and elongation of very long chain fatty acids protein (ELOVL) 5 was measured in proliferating T-cells compared with resting T-cells. No quantifiable ELOVL2 was measured. Knockdown of ELOVL5 in T-cells and Jurkat cells significantly affected cellular monounsaturated and PUFA profiles and strongly impaired the elongation of 18- and 20-carbon PUFAs. In conclusion, the induction of proliferation in human T-cells is associated with a significant increase in the capacity to take up and metabolize exogenous PUFAs, and ELOVL5 is responsible for the elongation of 18- and 20-carbon PUFAs in these cells.

Fatty acid remodeling in cellular glycerophospholipids following the activation of human T cells.

Changes in fatty acid (FA) and glycerophospholipid (GPL) metabolism associated with cell cycle entry are not fully understood. In this study FA-GPL remodeling was investigated in resting and proliferating primary human T cells. Significant changes were measured in the composition and distribution of FAs in GPLs following receptor activation of human T cells. The FA distribution of proliferating T cells was very similar to that of the human Jurkat T cell line and when the stimulus was removed from proliferating T cells, they stopped proliferating and the FA distribution largely reverted back to that of resting T cells. The cellular content of saturated and monounsaturated FAs was significantly increased in proliferating cells, which was associated with an induction of FA synthase and stearoyl-CoA desaturase-1 gene expression. Additionally, cellular arachidonate was redistributed in GPLs in a distinct pattern that was unlike any other FAs. This redistribution was associated with an induction of CoA-dependent and CoA-independent remodeling. Accordingly, significant changes in the expression of several acyl-CoA synthetases, lysophospholipid acyltransferases, and phospholipase A2 were measured. Overall, these results suggest that metabolic pathways are activated in proliferating T cells that may represent fundamental changes associated with human cell proliferation.