The remodeling of PUFAs by the Lands cycle is responsible for the diversity of
phospholipid molecular species found in cells. There have not been detailed studies of the alteration of
phospholipid molecular species as a result of serum
starvation or depletion of PUFAs that typically occurs during tissue culture. The time-dependent effect of cell culture on
phospholipid molecular species in RAW 264.7 cells cultured for 24, 48, or 72 h was examined by lipidomic strategies. These cells were then stimulated to produce arachidonate metabolites derived from the
cyclooxygenase pathway,
thromboxane B2,
PGE2, and
PGD2, and the
5-lipoxygenase pathway,
leukotriene (LT)B4,
LTC4, and
5-HETE, which decreased with increasing time in culture. However, the
5-lipoxygenase metabolites of a 20:3
fatty acid,
LTB3, all trans-LTB3, LTC3, and 5-hydroxyeicosatrienoic
acid, time-dependently increased. Molecular species of arachidonate containing
phospholipids were drastically remodeled during cell culture, with a new 20:3 acyl group being populated into
phospholipids to replace increasingly scarce arachidonate. In addition, the amount of TNFα induced by
lipopolysaccharide stimulation was significantly increased in the cells cultured for 72 h compared with 24 h, suggesting that the remodeling of PUFAs enhanced inflammatory response. These studies supported the rapid operation of the Lands cycle to maintain cell growth and viability by populating PUFA species; however, without sufficient
n-6 fatty acids, 20:3 n-9 accumulated, resulting in altered
lipid mediator biosynthesis and inflammatory response.