A PIP5 Kinase Essential for Efficient Chemotactic Signaling

作者：Fets Louise^*; Nichols John M E; Kay Robert R

来源：Current Biology, 2014, 24(4): 415-421.

DOI：10.1016/j.cub.2013.12.052

In neutrophils and Dictyostelium, chemoattractant gradients generate directed cell migration by eliciting signaling events that bias intrinsic motility and favor the production and retention of upgradient pseudopods [1, 2]. Phosphoinositides are actively regulated during chemotaxis in these cells, most iconically in the production of PI(3,4,5)P-3 gradients within the plasma membrane [3, 4]. Although it is now known that PI(3,4,5) P3 signaling is nonessential for gradient sensing [5, 6], the role of the related phosphoinositide PI(4,5)P-2 is little understood, despite its clear importance in many cell biological processes [7]. We describe here a PIP5 kinase, Pikl, which produces PI(4,5) P2 and is essential for efficient chemotaxis of Dictyostelium cells. Without PikI, PI(4,5) P2 levels are reduced by 90%, and while pikl(-) cells move at normal speeds, they are highly disorientated in cAMP gradients. Following chemotactic stimulation, Ras is efficiently activated in pikl(-) cells, yet Ras-dependent responses (including activation of PKB) are severely impaired. Pikl is phosphorylated by PKB [8], and in vitro studies of a phosphomimic mutant suggest that this phosphorylation increases Pikl activity. We propose that adequate PI(4,5) P2 levels are required to couple activated Ras to its downstream effectors and that these levels are regulated by Pikl, making it a crucial player in gradient sensing.

• 出版日期2014-2-17
• 单位河北医科大学