ABSTRACT
Novel therapeutics are required for improving the management of chronic inflammatory diseases. Aptamers are single-stranded RNA or DNA molecules that have recently shown utility in a clinical setting, as they can specifically neutralize biomedically relevant proteins, particularly cell surface and extracellular proteins. The nuclear chromatin protein DEK is a secreted chemoattractant that is abundant in the synovia of patients with juvenile idiopathic arthritis (JIA). Here, we show that DEK is crucial to the development of arthritis in mouse models, thus making it an appropriate target for aptamer-based therapy. Genetic depletion of DEK or treatment with DEK-targeted aptamers significantly reduces joint inflammation in vivo and greatly impairs the ability of neutrophils to form neutrophil extracellular traps (NETs). DEK is detected in spontaneously forming NETs from JIA patient synovial neutrophils, and DEK-targeted aptamers reduce NET formation. DEK is thus key to joint inflammation, and anti-DEK aptamers hold promise for the treatment of JIA and other types of arthritis.
Subject(s)
Aptamers, Nucleotide/therapeutic use , Arthritis, Juvenile/therapy , Chemotactic Factors/antagonists & inhibitors , Chromosomal Proteins, Non-Histone/antagonists & inhibitors , DNA-Binding Proteins/genetics , Extracellular Traps/immunology , Oncogene Proteins/antagonists & inhibitors , Oncogene Proteins/genetics , Poly-ADP-Ribose Binding Proteins/antagonists & inhibitors , Poly-ADP-Ribose Binding Proteins/genetics , Adult , Animals , Arthritis, Juvenile/immunology , Chemotactic Factors/genetics , Chemotactic Factors/immunology , Chemotactic Factors/metabolism , Chromosomal Proteins, Non-Histone/genetics , Chromosomal Proteins, Non-Histone/immunology , Chromosomal Proteins, Non-Histone/metabolism , DNA-Binding Proteins/antagonists & inhibitors , DNA-Binding Proteins/metabolism , Disease Models, Animal , Extracellular Traps/metabolism , Female , Healthy Volunteers , Humans , Male , Mice , Mice, Inbred C57BL , Mice, Knockout , Neutrophils/immunology , Oncogene Proteins/immunology , Oncogene Proteins/metabolism , Poly-ADP-Ribose Binding Proteins/immunology , Poly-ADP-Ribose Binding Proteins/metabolism , Primary Cell Culture , Synovial Fluid/chemistry , Synovial Fluid/cytology , Synovial Fluid/immunology , Zymosan/immunologyABSTRACT
Oxidative stress is caused by an increase in reactive oxygen species (ROS) relative to the antioxidant defense system. An increase in ROS is known to decrease vascular function, increase inflammatory cytokines, and promote adipocyte hypertrophy. A known regulator of the oxidative stress response is the heat shock protein, heme-oxygenase 1 (HO-1), which is induced by cobalt protoporphyrin IX (CoPP). Menin was recently found to promote the sustained expression of heat shock proteins and is implicated in the regulation of oxidative stress. In this study, we investigated how changes in menin expression affected adipogenesis via the interaction between endothelial cells and adipocytes in response to CoPP treatment during oxidative stress. Using angiotensin II (Ang II) to induce oxidative stress in endothelial cells and adipocytes, we observed the induction of various cytokines including EGF, VEGF, angiogenin, IL-6, and MCP-1. Preadipocytes cultured in endothelial cell conditioned media treated with Ang II showed no changes in differentiation markers. Preadipocytes treated with the endothelial cell-conditioned media pretreated with CoPP resulted in an increase in the number of adipocytes, which expressed higher levels of adipocyte differentiation markers in direct correlation with the complete downregulation of the stress response regulator, menin. This change was not detected in adipocytes directly treated with CoPP alone. Therefore, we concluded that loss of menin is associated with the maturation of adipocytes induced by conditioned media from endothelial cells treated with CoPP.
ABSTRACT
Menin is the ubiquitously expressed nuclear protein product of the MEN1 gene, which interacts with PKB/Akt in the cytoplasm to inhibit its activity. This study describes a novel insulin-dependent mechanism of menin regulation and interaction with other metabolic proteins. We show that insulin downregulated menin in a time-dependent manner via the human insulin receptor. Inhibition analysis indicated a critical role for the protein kinase Akt in regulation of menin expression and localization. Insulin-mediated decrease in menin expression was abrogated by the PI3K/Akt inhibitor LY-294002 at early time points, from 2 to 7 h. Furthermore, exposure to insulin resulted in the cytoplasmic localization of menin and increased interaction with FOXO1. Fasting followed by refeeding modulates serum insulin levels, which corresponded to an increase in menin interaction with FOXO1 in the liver. Liver-specific hemizygous deletion of menin resulted in increased expression of FOXO1 target genes, namely IGFBP-1, PGC-1α, insulin receptor, Akt, and G-6-Pase. This study provides evidence that menin expression and localization are regulated by insulin signaling and that this regulation triggers an increase in its interaction with FOXO1 via Akt with metabolic consequences.
