Disruption of CTCF-mediated IGF2 repression promotes AKT-dependent mitochondrial oxidative stress and chondrocyte senescence in osteoarthritis.
Abstract
Aims
The upstream epigenetic mechanisms linking chronic inflammation to mitochondrial dysregulation and chondrocyte senescence in osteoarthritis (OA) remain incompletely defined. This study investigated whether inflammation-associated loss of CTCF occupancy at the IGF2-H19 intergenic region contributes to IGF2 upregulation, AKT-dependent mitochondrial oxidative stress, and chondrocyte senescence.
Materials And Methods
Integrative transcriptomic analysis of GSE114007 was performed using DESeq2, WGCNA, and protein-protein interaction network analysis. Key findings were examined in human OA cartilage and mechanistically investigated in cytokine-stimulated C28/I2 chondrocytes using chromatin immunoprecipitation, mitochondrial functional profiling, and senescence assays. Mechanistic studies combined CTCF gain- and loss-of-function approaches with pharmacological targeting of IGF2, AKT, and mitochondrial ROS. IGF2 neutralization was further evaluated in an ACLT murine model. KEY
Findings
IGF2 emerged as a transcriptomic hub gene associated with mitochondrial and senescence-related networks in OA. Inflammatory stimulation reduced CTCF expression and occupancy at the IGF2-H19 intergenic region, accompanied by increased IGF2 expression, AKT activation, mitochondrial respiratory activity, ROS production, matrix catabolism, and senescence-associated phenotypes. CTCF overexpression attenuated IGF2 upregulation and oxidative/senescence-associated phenotypes, whereas CTCF knockdown elicited complementary changes. Targeting IGF2, AKT, or mitochondrial ROS reduced oxidative stress and senescence-associated changes. In vivo, IGF2 neutralization attenuated cartilage degeneration, matrix catabolism, AKT activation, and senescence-associated alterations.
Significance
These findings support a functional regulatory framework linking CTCF-IGF2 dysregulation with AKT-dependent mitochondrial oxidative stress and chondrocyte senescence in OA, highlighting IGF2 signaling as a potential therapeutic target.