Zhen Wang1, Tatiana Boyko1, Misha C Tran1, Marie LaRussa1, Namrata Bhatia1, Vania Rashidi1, Michael T Longaker1, George P Yang2. 1. Department of Surgery, Stanford University School of Medicine, Stanford, California. 2. Department of Surgery, Stanford University School of Medicine, Stanford, California; Palo Alto VA Health Care System, Palo Alto, California; UAB Department of Surgery, 1808 7th Ave South, Suite 502, Birmingham, Alabam. Electronic address: gpyang@uab.edu.
Abstract
BACKGROUND: Osteoarthritis (OA) is a debilitating disease process, affecting mobility and overall health of millions. Current treatment is for symptomatic relief and discovery of approaches to halt or reverse damage is imperative. Deletion of developmental endothelial locus-1 (Del1) has been shown to increase severity of OA in knockout mice. We examined the intracellular pathways involved in the ability of DEL1 to protect chondrocytes from apoptosis and anoikis and hypothesized that it functioned via integrin signaling. MATERIALS AND METHODS: Primary human chondrocytes were treated with various inducers of apoptosis, including anoikis, in the presence of added DEL1 or bovine serum albumin as control. Various inhibitors of integrin binding were examined for their effect on DEL1 activity. Downstream signaling pathway components were detected by immunoblotting. RESULTS: The addition of DEL1 protected chondrocytes from multiple inducers of apoptosis as measured by cell survival, terminal deoxynucleotidyl transferase dUTP nick end labeling and caspase 3/7 assays (P < 0.05). The effect of DEL1 was blocked by RGD peptides and by antibodies directed to integrin αVβ3, but not by controls or antibody to integrin α1 (P < 0.05). Treatment with DEL1 promoted ERK and AKT activation when cells were attached, but only AKT activation under conditions of anoikis. CONCLUSIONS: DEL1 protected chondrocytes from apoptosis in response to activators of either the intrinsic or extrinsic pathways, and to anoikis. This effect was mediated primarily through integrin αVβ3. This represents a therapeutic target for therapies to prevent cartilage degeneration in OA. Published by Elsevier Inc.
BACKGROUND:Osteoarthritis (OA) is a debilitating disease process, affecting mobility and overall health of millions. Current treatment is for symptomatic relief and discovery of approaches to halt or reverse damage is imperative. Deletion of developmental endothelial locus-1 (Del1) has been shown to increase severity of OA in knockout mice. We examined the intracellular pathways involved in the ability of DEL1 to protect chondrocytes from apoptosis and anoikis and hypothesized that it functioned via integrin signaling. MATERIALS AND METHODS: Primary human chondrocytes were treated with various inducers of apoptosis, including anoikis, in the presence of added DEL1 or bovine serum albumin as control. Various inhibitors of integrin binding were examined for their effect on DEL1 activity. Downstream signaling pathway components were detected by immunoblotting. RESULTS: The addition of DEL1 protected chondrocytes from multiple inducers of apoptosis as measured by cell survival, terminal deoxynucleotidyl transferase dUTP nick end labeling and caspase 3/7 assays (P < 0.05). The effect of DEL1 was blocked by RGD peptides and by antibodies directed to integrin αVβ3, but not by controls or antibody to integrin α1 (P < 0.05). Treatment with DEL1 promoted ERK and AKT activation when cells were attached, but only AKT activation under conditions of anoikis. CONCLUSIONS:DEL1 protected chondrocytes from apoptosis in response to activators of either the intrinsic or extrinsic pathways, and to anoikis. This effect was mediated primarily through integrin αVβ3. This represents a therapeutic target for therapies to prevent cartilage degeneration in OA. Published by Elsevier Inc.
Authors: Andrew D Foers; Laura F Dagley; Simon Chatfield; Andrew I Webb; Lesley Cheng; Andrew F Hill; Ian P Wicks; Ken C Pang Journal: Clin Transl Immunology Date: 2020-11-07