N-myc downregulated gene 1 is a phosphorylated protein in mast cells.
We previously demonstrated that the in vitro maturation of mouse immature bone marrow-derived mast cells into a mature connective tissue mast cell-like phenotype is accompanied by a marked induction of N-myc downregulated gene (NDRG) 1, a cytosolic protein with unknown function. Here we show that NDRG1 undergoes phosphorylation in mast cells. Recombinant NDRG1 was phosphorylated by calmodulin kinase-II, protein kinase (PK) A and PKC in vitro. Deletion of the C-terminal tandem repeats of NDRG1 resulted in increased phosphorylation by PKA and PKC, but not by calmodulin kinase-II. Furthermore, NDRG1 was phosphorylated on serine and threonine residues in mast cells, a process that was accelerated transiently following cell activation. Pharmacologic studies using kinase-specific inhibitors demonstrated that this NDRG1 phosphorylation in mast cells depended on calmodulin kinase-II and PKA, but not PKC. Collectively, our results indicate that NDRG1 is a multiphosphorylated protein in mast cells, and that the kinetics of increased NDRG1 phosphorylation parallels signaling events leading to exocytosis.
Sugiki
Toshihiko
T
Department of Health Chemistry, School of Pharmaceutical Sciences, Showa University, Tokyo, Japan.
Murakami
Makoto
M
Taketomi
Yoshitaka
Y
Kikuchi-Yanoshita
Rei
R
Kudo
Ichiro
I
D000818:Animals; D018797:Cell Cycle Proteins / Q000235:genetics / Q000378:metabolism*; D045744:Cell Line, Tumor; D015536:Down-Regulation; D016259:Genes, myc; D047908:Intracellular Signaling Peptides and Proteins; D008407:Mast Cells / Q000378:metabolism*; D010766:Phosphorylation; D011499:Protein Processing, Post-Translational; D051381:Rats; D000099259:N-myc Downstream-Regulated Gene 1 Protein
D018797:Cell Cycle Proteins; D047908:Intracellular Signaling Peptides and Proteins; D000099259:N-myc Downstream-Regulated Gene 1 Protein