Cytoplasmic pH-dependent spreading of polymorphonuclear leukocytes: regulation by pH of PKC subcellular distribution and F-actin assembly.
Cytoplasmic pH (pHi) plays an important role in the regulation of polymorphonuclear leukocyte (PMN) spreading, but the molecular mechanisms involved have long been obscure. In the present study, we investigated the pH-dependence of phorbol myristate acetate (PMA)-induced PMN spreading. A change in pHi alone did not induce spreading, but cytoplasmic alkalinization promoted the spreading induced by PMA, whereas acidification inhibited it. To further investigate the mechanism by which pHi affects cell spreading, we employed subcellular fractionation and immunoblot analyses to evaluate the effect of pH on the subcellular distribution of protein kinase C (PKC) and assembly of the actin cytoskeleton. We found that cytoplasmic alkalinization enhanced PKC membrane distribution and quantitatively up-regulated the actin cytoskeleton. On the other hand, cytoplasmic acidification was found to have effects on these signaling molecules that were opposite to those of cytoplasmic alkalinization. These results may provide a potential explanation for the pH-regulation of the PMA-induced PMN spreading.
Suzuki
Kingo
K
Department of Biology, School of Education, Waseda University, Nishi-Waseda 1-6-1, Shinjuku-ku, Tokyo 169-0051, Japan. kingo@kurenai.waseda.jp
Namiki
Hideo
H
D000199:Actins / Q000378:metabolism* / Q000648:ultrastructure; D000818:Animals; D002448:Cell Adhesion / Q000187:drug effects / Q000502:physiology; D002465:Cell Movement / Q000187:drug effects / Q000502:physiology; D003593:Cytoplasm / Q000378:metabolism*; D003599:Cytoskeleton / Q000378:metabolism; D005109:Extracellular Matrix / Q000378:metabolism; D005452:Fluoresceins; D006863:Hydrogen-Ion Concentration / Q000187:drug effects; D009504:Neutrophils / Q000166:cytology* / Q000378:metabolism* / Q000648:ultrastructure; D010590:Phalloidine / Q000031:analogs & derivatives; D011493:Protein Kinase C / Q000187:drug effects / Q000378:metabolism*; D015398:Signal Transduction / Q000502:physiology*; D013347:Subcellular Fractions / Q000187:drug effects / Q000378:metabolism*; D013552:Swine; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology
D000199:Actins; D005452:Fluoresceins; C037191:fluorescein isothiocyanate-phalloidin; C057433:2',7'-bis-(2-carboxyethyl)-5(6)-carboxyfluorescein acetoxymethyl ester; D010590:Phalloidine; D011493:Protein Kinase C; D013755:Tetradecanoylphorbol Acetate