Chloride conductance is required for the protein kinase A and Rac1-dependent phosphorylation of moesin at Thr-558 by KCl in PC12 cells.
Moesin is a member of the ERM family, a family of cross-linkers between the plasma membrane and the actin cytoskeleton, which are known to be activated by phosphorylation. Previously, we reported the RhoA and Rho kinase-dependent phosphorylation of moesin at Thr-558 in hippocampal neuronal cells by glutamate. Here we studied the induction of moesin phosphorylation by KCl (60 mm) in PC12 cells. Moesin phosphorylation at Thr-558 was increased after 2 min of KCl treatment, peaked at 5 min, and returned to the basal level by 60 min. KCl also activated Rac1, but not RhoA, in PC12 cells, and KCl-induced moesin phosphorylation was suppressed in dominant negative Rac1 (N17 Rac1)-expressed cells. The inhibition of protein kinase A (PKA), known as an upstream kinase of Rac1, abolished Rac1 activation and moesin phosphorylation by KCl. Interestingly, the phosphorylation of moesin by KCl was independent of KCl-induced membrane depolarization and calcium influx but was dependent on KCl-induced chloride conductance. 60 mm KCl induced chloride conductance in PC12 cells, and pretreatment with Cl- channel blocker abolished Rac1 activation and moesin phosphorylation by KCl. These results suggest that the phosphorylation of moesin at Thr-558 in PC12 cells by KCl treatment is PKA- and Rac1-dependent and that KCl-induced chloride conductance is involved in the activation of this signaling system.
Jeon
Songhee
S
Department of Molecular Cell Biology, Samsung Biomedical Research Institute, and Center for Neuronal Cell Excitability Research, Sungkyunkwan University School of Medicine, Suwon 440-746, Korea.
Kim
Sohee
S
Kim
Eunhee
E
Lee
Ji Eun
JE
Kim
Sung Joon
SJ
Juhnn
Yong-Sung
YS
Kim
Yong Sik
YS
Bae
Chang-Dae
CD
Park
Joobae
J
D000818:Animals; D018118:Chloride Channels / Q000378:metabolism*; D002712:Chlorides / Q000378:metabolism*; D016895:Culture Media, Serum-Free / Q000494:pharmacology; D017868:Cyclic AMP-Dependent Protein Kinases / Q000378:metabolism*; D004591:Electrophoresis, Polyacrylamide Gel; D015151:Immunoblotting; D008840:Microfilament Proteins / Q000737:chemistry / Q000378:metabolism*; D016716:PC12 Cells; D018408:Patch-Clamp Techniques; D010766:Phosphorylation; D010957:Plasmids / Q000378:metabolism; D011188:Potassium / Q000737:chemistry; D011189:Potassium Chloride / Q000378:metabolism*; D051381:Rats; D015398:Signal Transduction; D013912:Threonine / Q000378:metabolism*; D013997:Time Factors; D014162:Transfection; D020830:rac1 GTP-Binding Protein / Q000378:metabolism*; D020742:rhoA GTP-Binding Protein / Q000378:metabolism
D018118:Chloride Channels; D002712:Chlorides; D016895:Culture Media, Serum-Free; D008840:Microfilament Proteins; C071058:moesin; D013912:Threonine; D011189:Potassium Chloride; D017868:Cyclic AMP-Dependent Protein Kinases; D020830:rac1 GTP-Binding Protein; D020742:rhoA GTP-Binding Protein; D011188:Potassium