Polarized growth: maintaining focus on the tip.
Tip growth, a spatially focused cell expansion, has been best characterized in two plant cell types: pollen tubes and root hairs. It has long been established that both cell types require three intracellular components for this process: a tip-high calcium gradient, a polarized actin cytoskeleton, and tip-directed vesicle trafficking. More recently, additional mechanistic parallels have been observed between the two cell types, including roles for ROP and Rab GTPase signaling, phosphoinositides, calcium-dependent protein kinases, and the exocyst. Uncovering pathways that control the three components is beginning to reveal a highly interconnected network, which we call the tip growth LENS (for localization enhancing network, self-sustaining), that coordinates the required cellular activities to allow regulated tip growth, and to maintain itself as the tip advances.
Cole
Rex A
RA
Molecular and Cellular Biology Program, Oregon State University, Corvallis, Oregon 97331, USA.
Fowler
John E
JE
D002118:Calcium / Q000378:metabolism; D016764:Cell Polarity; D059828:Plant Cells; D063245:Plant Development; D010940:Plant Proteins / Q000378:metabolism; D018517:Plant Roots / Q000166:cytology / Q000254:growth & development
D010940:Plant Proteins; D002118:Calcium