Phosphatidylinositol‐3,4,5‐trisphospate (PIP3) is a potent signaling lipid that exerts key control over cell growth, survival, adhesion and migration. PIP3 signaling is often disrupted in various cancers, making understanding the regulation of PIP3 signaling an important priority. Much has been learned from the study of phosphorylation of the inositol headgroup of phosphoinositides, such as the phosphorylation of phosphatidylinositol‐4,5‐bisphospate (PIP2) to produce PIP3, as well as negative regulation of PIP3 by phosphoinositide phosphatases such as PTEN. However, much less is known about another key dimension of control of phosphoinositide action, the regulation of the fatty acyl profile of these lipids. Indeed, phosphatidylinositol and phosphoinositides exhibit remarkable selectivity of acyl chains (>50% harboring 1‐stearoyl, 2‐arachidonoyl), an acyl profile quite distinct from other phospholipids. This suggests that control of fatty acyl profile of phosphoinositides may be an important determinant of the function of these lipids that has to date remained largely unexplored. We recently uncovered that the acyltransferase LYCAT is a key regulator of the acyl profile of specific phosphoinositides such as PIP2, thus exerting control over membrane traffic phenomena dependent on these phosphoinositides (Bone LN et al 2017 Mol Biol Cell. 28:161–172). We now examine how LYCAT controls PIP3 signaling and PIP3‐dependent control of cell physiology, including the activation of Akt and control of actin dynamics. We find that LYCAT perturbation impairs the activation of Akt and the activation of a number of Akt substrates, which in turn impacts cell growth and survival. Furthermore, LYCAT perturbation elicits dramatic changes in actin filament morphology, cell migration and cancer cell invasion. These results indicate that control of phosphoinositide acyl chain profile is an important novel dimension of regulation of PIP3 signaling, impacting proliferative, growth and migration signaling, and as such may be a novel dimension to control of cancer cell growth and progression.Support or Funding InformationThis work was supported by an Ontario Early Researcher Award, a Canada Research Chair Award, and a Natural Sciences and Engineering Research Council Grant to R.J.B, and a Project Grant and New Investigator Salary Award from the Canadian Institutes of Health Research to C.N.A.This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.