The dual specificity phosphatases M3/6 and MKP-3 are highly selective for inactivation of distinct mitogen-activated protein kinases.
The mitogen-activated protein (MAP) kinase family includes extracellular signal-regulated kinase (ERK), c-Jun NH2-terminal kinase/stress-activated protein kinase (JNK/SAPK) and p38/RK/CSBP (p38) as structurally and functionally distinct enzyme classes. Here we describe two new dual specificity phosphatases of the CL100/MKP-1 family that are selective for inactivating ERK or JNK/SAPK and p38 MAP kinases when expressed in COS-7 cells. M3/6 is the first phosphatase of this family to display highly specific inactivation of JNK/SAPK and p38 MAP kinases. Although stress-induced activation of p54 SAPKbeta, p46 SAPKgamma (JNK1) or p38 MAP kinases is abolished upon co-transfection with increasing amounts of M3/6 plasmid, epidermal growth factor-stimulated ERK1 is remarkably insensitive even to the highest levels of M3/6 expression obtained. In contrast to M3/6, the dual specificity phosphatase MKP-3 is selective for inactivation of ERK family MAP kinases. Low level expression of MKP-3 blocks totally epidermal growth factor-stimulated ERK1, whereas stress-induced activation of p54 SAPKbeta and p38 MAP kinases is inhibited only partially under identical conditions. Selective regulation by M3/6 and MKP-3 was also observed upon chronic MAP kinase activation by constitutive p21(ras) GTPases. Hence, although M3/6 expression effectively blocked p54 SAPKbeta activation by p21(rac) (G12V), ERK1 activated by p21(ras) (G12V) was insensitive to this phosphatase. ERK1 activation by oncogenic p21(ras) was, however, blocked totally by co-expression of MKP-3. This is the first report demonstrating reciprocally selective inhibition of different MAP kinases by two distinct dual specificity phosphatases.
Muda
M
M
Geneva Biomedical Research Institute, Glaxo Wellcome Research and Development S. A., CH-1228 Plan-les-Ouates, Geneva, Switzerland. SA7182@GGR.CO.UK
Theodosiou
A
A
Rodrigues
N
N
Boschert
U
U
Camps
M
M
Gillieron
C
C
Davies
K
K
Ashworth
A
A
Arkinstall
S
S
D000595:Amino Acid Sequence; D000818:Animals; D001665:Binding Sites; D019556:COS Cells; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D003001:Cloning, Molecular; D054642:Dual Specificity Phosphatase 6; D004789:Enzyme Activation; D004815:Epidermal Growth Factor / Q000494:pharmacology; D019204:GTP-Binding Proteins / Q000378:metabolism; D051379:Mice; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases; D008969:Molecular Sequence Data; D010446:Peptide Fragments / Q000737:chemistry; D010749:Phosphoprotein Phosphatases / Q000737:chemistry / Q000378:metabolism*; D017027:Protein Tyrosine Phosphatases / Q000737:chemistry / Q000378:metabolism*; D016283:Proto-Oncogene Proteins p21(ras) / Q000378:metabolism; D011994:Recombinant Proteins / Q000737:chemistry / Q000378:metabolism; D013379:Substrate Specificity; D014162:Transfection; D020744:rac GTP-Binding Proteins
D010446:Peptide Fragments; D011994:Recombinant Proteins; D004815:Epidermal Growth Factor; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases; D010749:Phosphoprotein Phosphatases; D054642:Dual Specificity Phosphatase 6; C517036:Dusp6 protein, mouse; D017027:Protein Tyrosine Phosphatases; D019204:GTP-Binding Proteins; D016283:Proto-Oncogene Proteins p21(ras); D020744:rac GTP-Binding Proteins