Characterization of a novel low-molecular-mass dual-specificity phosphatase-3 (LDP-3) that enhances activation of JNK and p38.
We have isolated a mouse cDNA for a novel dual-specificity phosphatase designated LDP-3 (low-molecular-mass dual-specificity phosphatase 3). The 450 bp open reading frame encodes a protein of 150 amino acids with a predicted molecular mass of 16 kDa. Northern blot and reverse transcription-PCR analyses show that LDP-3 transcripts are expressed in almost all mouse tissues examined. In vitro analyses using several substrates and inhibitors indicate that LDP-3 possesses intrinsic dual-specificity phosphatase activity. When expressed in mammalian cells, LDP-3 protein is localized mainly to the apical submembrane area. Forced expression of LDP-3 does not alter activation of ERK (extracellular-signal-regulated kinase), but rather enhances activation of JNK (c-Jun N-terminal kinase) and p38 and their respective upstream kinases MKK4 (mitogen-activated protein kinase kinase 4) and MKK6 in cells treated with 0.4 M sorbitol. By screening with a variety of stimuli, we found that LDP-3 specifically enhances the osmotic stress-induced activation of JNK and p38.
Division of Biochemical Oncology and Immunology, Institute for Genetic Medicine, Hokkaido University, Kita-15, Nishi-7, Kita-ku, Sapporo 060-0815, Japan.
Kentaro
K
Takagaki
Takeshi
T
Satoh
Nobuhiro
N
Tanuma
Kouhei
K
Masuda
Mutsuhiro
M
Takekawa
Hiroshi
H
Shima
Kunimi
K
Kikuchi
D000595:Amino Acid Sequence; D000818:Animals; D019556:COS Cells / Q000201:enzymology; D002460:Cell Line; D002522:Chlorocebus aethiops; D054637:Dual-Specificity Phosphatases; D004789:Enzyme Activation / Q000235:genetics / Q000502:physiology; D006801:Humans; D048031:JNK Mitogen-Activated Protein Kinases / Q000378:metabolism*; D048768:MAP Kinase Kinase Kinase 4 / Q000378:metabolism; D051379:Mice; D048053:Mitogen-Activated Protein Kinase 6 / Q000378:metabolism; D008969:Molecular Sequence Data; D008970:Molecular Weight; D009154:Mutation / Q000235:genetics / Q000502:physiology; D009997:Osmotic Pressure; D017027:Protein Tyrosine Phosphatases / Q000737:chemistry* / Q000235:genetics / Q000502:physiology*; D013379:Substrate Specificity; D014162:Transfection / Q000379:methods; D048051:p38 Mitogen-Activated Protein Kinases / Q000378:metabolism*
D048031:JNK Mitogen-Activated Protein Kinases; D048053:Mitogen-Activated Protein Kinase 6; D048051:p38 Mitogen-Activated Protein Kinases; D048768:MAP Kinase Kinase Kinase 4; D054637:Dual-Specificity Phosphatases; C500227:Dusp23 protein, mouse; D017027:Protein Tyrosine Phosphatases