Oxidative stress decreases G protein-coupled receptor kinase 2 in lymphocytes via a calpain-dependent mechanism.
G protein-coupled receptor kinase (GRK) 2 plays a crucial role in regulating the extent of desensitization and resensitization of G protein-coupled receptors (GPCRs). We have shown that the expression level of GRK2 in lymphocytes decreases during inflammatory diseases such as arthritis. Reactive oxygen species play an important role in a variety of inflammatory conditions, including arthritis. We demonstrate herein that oxidative stress, induced by exposure of lymphocytes to H(2)O(2), results in a 50% reduction in GRK2 protein levels and GRK activity with no changes in mRNA expression. Treatment of lymphocytes with the tyrosine kinase inhibitor genistein partially reverses the effect of H(2)O(2) on GRK2 levels, although we did not detect direct tyrosine phosphorylation of GRK2. Inhibition of the nonproteasomal protease calpain by calpeptin can prevent the H(2)O(2)-induced GRK2 decrease. In vitro experiments confirm that GRK2 is partially digested by m-calpain in a calcium-dependent way. Functionally, H(2)O(2)-induced decrease in GRK2 levels is associated with an ~70% decrease in agonist-induced beta(2)-adrenergic receptor sequestration. We describe oxidative stress as a novel mechanism for regulation of the intracellular level of GRK2 during inflammatory processes. Moreover, our data demonstrate that oxidative stress may change the functioning of GPCRs via calpain-dependent regulation of GRK2 levels.
Department of Immunology, Laboratory of Psychoneuroimmunology, University Medical Center, Utrecht, The Netherlands.
Maria Stella
MS
Lombardi
Annemieke
A
Kavelaars
Petronila
P
Penela
Elisabeth J
EJ
Scholtens
Marta
M
Roccio
Reinhold E
RE
Schmidt
Manfred
M
Schedlowski
Federico
F
Mayor
Cobi J
CJ
Heijnen
D002154:Calpain / Q000378:metabolism*; D017868:Cyclic AMP-Dependent Protein Kinases / Q000378:metabolism*; D003546:Cysteine Endopeptidases; D015536:Down-Regulation; D054769:G-Protein-Coupled Receptor Kinase 2; D006801:Humans; D006861:Hydrogen Peroxide / Q000494:pharmacology; D019169:Jurkat Cells; D008214:Lymphocytes / Q000145:classification / Q000187:drug effects / Q000201:enzymology*; D018384:Oxidative Stress / Q000502:physiology*; D046988:Proteasome Endopeptidase Complex; D011506:Proteins / Q000378:metabolism; D018343:Receptors, Adrenergic, beta-2 / Q000378:metabolism; D051552:beta-Adrenergic Receptor Kinases
D011506:Proteins; D018343:Receptors, Adrenergic, beta-2; D006861:Hydrogen Peroxide; D017868:Cyclic AMP-Dependent Protein Kinases; C496567:GRK2 protein, human; D051552:beta-Adrenergic Receptor Kinases; D054769:G-Protein-Coupled Receptor Kinase 2; D002154:Calpain; D003546:Cysteine Endopeptidases; C449000:m-calpain; C088874:PSMB5 protein, human; D046988:Proteasome Endopeptidase Complex