Redox regulation of MAPK phosphatase 1 controls monocyte migration and macrophage recruitment

Abstract

Monocytic adhesion and chemotaxis are regulated by MAPK pathways, which in turn are controlled by redox-sensitive MAPK phosphatases (MKPs). We recently reported that metabolic disorders prime monocytes for enhanced recruitment into vascular lesions by increasing monocytes' responsiveness to chemoattractants. However, the molecular details of this proatherogenic mechanism were not known. Here we show that monocyte priming results in the S-glutathionylation and subsequent inactivation and degradation of MKP-1. Chronic exposure of human THP-1 monocytes to diabetic conditions resulted in the loss of MKP-1 protein levels, the hyperactivation of ERK and p38 in response to monocyte chemoattractant protein-1 (MCP-1), and increased monocyte adhesion and chemotaxis. Knockdown of MKP-1 mimicked the priming effects of metabolic stress, whereas MKP-1 overexpression blunted both MAPK activation and monocyte adhesion and migration induced by MCP-1. Metabolic stress promoted the Sglutathionylation of MKP-1, targeting MKP-1 for proteasomal degradation. Preventing MKP-1 S-glutathionylation in metabolically stressed monocytes by overexpressing glutaredoxin 1 protected MKP-1 from degradation and normalized monocyte adhesion and chemotaxis in response to MCP-1. Blood monocytes isolated from diabetic mice showed a 55% reduction in MKP-1 activity compared with nondiabetic mice. Hematopoietic MKP-1 deficiency in atherosclerosis-prone mice mimicked monocyte priming and dysfunction associated with metabolic disorders, increased monocyte chemotaxis in vivo, and accelerated atherosclerotic lesion formation. In conclusion, we identified MKP-1 as a central redox-sensitive regulator of monocyte adhesion and migration and showed that the loss of MKP-1 activity is a critical step in monocyte priming and the metabolic stress-induced conversion of blood monocytes into a proatherogenic phenotype.M etabolic disorders such as obesity and diabetes are associated with a state of chronic, low-grade inflammation (1, 2), which appears to contribute to the development of micro-and macrovascular complications such as atherosclerosis, nephropathy, and retinopathy (3-5). The cellular and molecular mechanisms involved in chronic inflammation associated with metabolic disorders are not yet fully understood, but the recruitment of blood monocytes to sites of vascular injury appears to play a central and rate-limiting role in all these complications. Metabolic disorders impact blood vessels at multiple levels, including lipid depositions, endothelial injury, and smooth muscle cell proliferation and migration, which individually or in concert initiate monocyte recruitment and promote vascular inflammation (6, 7). However, metabolic disorders also appear to affect blood monocytes directly. A number of studies reported that monocytes both in patients with metabolic disorders and in dyslipidemic or diabetic mice undergo phenotypical and functional changes that may contribute directly to the development and progression of chronic inflammatory vascular diseases (8-13)...

Mechanisms of Interferon-γ Production by Neutrophils and Its Function duringStreptococcus pneumoniaePneumonia

“…ROS modulate the activity of MAPKs by inhibiting phosphatases, resulting in sustained MAPK activation (46,47). The levels of phosphorylated and total MAPKs were determined in neutrophils isolated from the lungs of WT and Nox2-deficient mice given S. pneumoniae.…”

ProteinS-Glutathionylation Mediates Macrophage Responses to Metabolic Cues from the Extracellular Environment

“…Protein S-glutathionylation in THP-1 monocytes in response to metabolic stress and H 2 O 2 We showed previously that metabolic stress (and H 2 O 2 treatment) sensitizes monocytes to chemokine activation, converting these cells into a hypermigratory proatherogenic phenotype (32,62), a process we termed metabolic priming.…”

“…We went on to demonstrate that metabolic priming is mediated by S-glutathionylation of proteins involved in cell signaling, cytoskeletal remodeling, and cell migration (31,32,62), suggesting that protein S-glutathionylation might be a global molecular mechanism by which monocytes and macrophages alter the proteome to respond to cellular stimuli. To test this hypothesis, THP-1 monocytes were cultured in the absence or presence of either metabolic stress (low-density lipoprotein + high D-glucose [LDL+HG]) or thiol oxidative stress (H 2 O 2 ), and lysates from these cells were analyzed to identify and semiquantify S-glutathionylated proteins.…”

“…To date, only a few S-glutathionylated proteins have been validated as bona fide redox signaling transducers based on five criteria originally outlined by Mieyal et al (42). We recently identified three proteins critical for monocyte migration that fulfill these criteria: actin (36,62), mitogen-activated protein kinase phosphatase 1 (MKP-1) (32), and 14-3-3f (31). Others reported that phosphatase and tensin homolog deleted from chromosome 10 (PTEN) (11), protein tyrosine phosphatase 1B (PTP1B) (50), Na-H exchanger isoform 1 (NHE1) (33), caspase-1 (41), and paraoxonase 1 (PON1) (52) were found to be S-glutathionylated in monocytes and macrophages of varying lineages (11,33,41,50,52).…”

The Expanding List of Redox-Sensing Transcription Factors in Mammalian Cells

“…In addition to transcription factors, redox sensing proteins belonging to different categories including protein kinases, phosphatases, ion channels and structural proteins are also emerging [16][17][18][19]. It is poorly understood why cells contain so many redox sensing proteins.…”