Inactivation of dual-specificity phosphatases is involved in the regulation of extracellular signal-regulated kinases by heat shock and hsp72.

Abstract

Extracellular signal-regulated kinase 1 (ERK1) and ERK2 (ERK1/2) dramatically enhance survival of cells exposed to heat shock. Using Cos-7 cells and primary human fibroblasts (IMR90 cells), we demonstrated that heat shock activates ERKs via two distinct mechanisms: stimulation of the ERK-activating kinases, MEK1/2, and inhibition of ERK dephosphorylation. Under milder heat shock conditions, activation of ERKs proceeded mainly through stimulation of MEK1/2, whereas under more severe heat shock MEK1/2 could no longer be activated and the inhibition of ERK phosphatases became critical. In Cos-7 cells, nontoxic heat shock caused rapid inactivation of the major ERK phosphatase, MKP-3, by promoting its aggregation, so that in cells exposed to 45 degrees C for 20 min, 90% of MKP-3 became insoluble. MKP-3 aggregation was reversible and, 1 h after heat shock, MKP-3 partially resolubilized. The redistribution of MKP-3 correlated with an increased rate of ERK dephosphorylation. Similar heat-induced aggregation, followed by partial resolubilization, was found with a distinct dual-specificity phosphatase MKP-1 but not with MKP-2. Therefore, MKP-3 and MKP-1 appeared to be critical heat-labile phosphatases involved in the activation of ERKs by heat shock. Expression of the major heat shock protein Hsp72 inhibited activation of MEK1/2 and prevented inactivation of MKP-3 and MKP-1. Hsp72DeltaEEVD mutant lacking a chaperone activity was unable to protect MKP-3 from heat inactivation but interfered with MEK1/2 activation similar to normal Hsp72. Hence, Hsp72 suppressed ERK activation by both protecting dual-specificity phosphatases, which was dependent on the chaperone activity, and suppressing MEK1/2, which was independent of the chaperone activity.

• Authors: Julia Yaglom, Cornelia O'Callaghan-Sunol, Vladimir Gabai, Michael Y Sherman
• Journal: Molecular and cellular biology (Mol Cell Biol) Vol. 23 Issue 11 Pg. 3813-24 (Jun 2003) ISSN: 0270-7306 [Print] United States
• PMID: 12748284 (Publication Type: Journal Article, Research Support, U.S. Gov't, P.H.S.)

Chemical References

• Cell Cycle Proteins
• HSP72 Heat-Shock Proteins
• Heat-Shock Proteins
• Immediate-Early Proteins
• MAP2K2 protein, human
• Protein-Tyrosine Kinases
• Protein Serine-Threonine Kinases
• Mitogen-Activated Protein Kinases
• MAP Kinase Kinase 1
• MAP Kinase Kinase 2
• MAP2K1 protein, human
• Mitogen-Activated Protein Kinase Kinases
• Phosphoprotein Phosphatases
• Protein Phosphatase 1
• Phosphoric Monoester Hydrolases
• DUSP1 protein, human
• Dual Specificity Phosphatase 1
• Protein Tyrosine Phosphatases

Topics

• Animals
• COS Cells
• Cell Aggregation
• Cell Cycle Proteins
• Cell Fractionation
• Dual Specificity Phosphatase 1
• Enzyme Activation
• Fibroblasts (cytology, metabolism)
• HSP72 Heat-Shock Proteins
• Heat-Shock Proteins (genetics, metabolism)
• Hot Temperature
• Humans
• Immediate-Early Proteins (metabolism)
• MAP Kinase Kinase 1
• MAP Kinase Kinase 2
• Mitogen-Activated Protein Kinase Kinases (metabolism)
• Mitogen-Activated Protein Kinases (metabolism)
• Phosphoprotein Phosphatases
• Phosphoric Monoester Hydrolases (metabolism)
• Protein Phosphatase 1
• Protein Serine-Threonine Kinases (metabolism)
• Protein Tyrosine Phosphatases (metabolism)
• Protein-Tyrosine Kinases (metabolism)
• Substrate Specificity
• Ultraviolet Rays