Regulation of macropinocytosis by p21-activated kinase-1

S. Dharmawardhane, A. Schurmann, M. A. Sells, J. Chernoff, S. L. Schmid, G. M. Bokoch

Research output: Contribution to journalArticlepeer-review

246 Scopus citations

Abstract

The process of macropinocytosis is an essential aspect of normal cell function, contributing to both growth and motile processes of cells. p21-activated kinases (PAKs) are targets for activated Rac and Cdc42 guanosine 5'-triphosphatases and have been shown to regulate the actin-myosin cytoskeleton. In fibroblasts PAK1 localizes to areas of membrane ruffling, as well as to amiloride-sensitive pinocytic vesicles. Expression of a PAK1 kinase autoinhibitory domain blocked both platelet-derived growth factor- and RacQ61L-stimulated uptake of 70-kDa dextran particles, whereas an inactive version of this domain did not, indicating that PAK kinase activity is required for normal growth factor-induced macropinocytosis. The mechanisms by which PAK modulate macropinocytosis were examined in NIH3T3 cell lines expressing various PAK1 constructs under the control of a tetracycline-responsive transactivator. Cells expressing PAK1 (H83,86L), a mutant that dramatically stimulates formation of dorsal membrane ruffles, exhibited increased macropinocytic uptake of 70-kDa dextran particles in the absence of additional stimulation. This effect was not antagonized by coexpression of dominant-negative Rac1-T17N. In the presence of platelet-derived growth factor, both PAK1 (H83,86L) and a highly kinase active PAK1 (T423E) mutant dramatically enhanced the uptake of 70-kDa dextran. Neither wild-type PAK1 nor vector controls exhibited enhanced macropinocytosis, nor did PAK1 (H83,86L) affect clathrin-dependent endocytic mechanisms. Active versions of PAK1 enhanced both growth factor-stimulated 70-kDa dextran uptake and efflux, suggesting that PAK1 activity modulated pinocytic vesicle cycling. These data indicate that PAK1 plays an important regulatory role in the process of macropinocytosis, perhaps related to the requirement for PAK in directed cell motility.

Original languageEnglish
Pages (from-to)3341-3352
Number of pages12
JournalMolecular Biology of the Cell
Volume11
Issue number10
DOIs
StatePublished - 2000

Keywords

  • 3T3 Cells
  • Amino Acid Substitution
  • Animals
  • Becaplermin
  • Biological Transport/drug effects
  • Dextrans/pharmacokinetics
  • Genetic Vectors
  • Mice
  • Mutagenesis, Site-Directed
  • Pinocytosis/drug effects
  • Platelet-Derived Growth Factor/pharmacology
  • Protein Serine-Threonine Kinases/genetics
  • Proto-Oncogene Proteins c-sis
  • Recombinant Proteins/metabolism
  • Trans-Activators/metabolism
  • Transfection
  • p21-Activated Kinases
  • rac1 GTP-Binding Protein/metabolism

Fingerprint

Dive into the research topics of 'Regulation of macropinocytosis by p21-activated kinase-1'. Together they form a unique fingerprint.

Cite this