Abstract Body:
Introduction:
Diabetic vascular complications are driven by endothelial dysfunction, yet the role of 3D genome organization in this process is unknown. We sought to define the alterations in chromatin architecture in diabetic endothelium and identify the key regulators involved.
Aims:
This study aimed to generate a high-resolution 3D genome atlas of diabetic endothelium, uncover the role of JUNB as a key architectural transcription factor, and identify RBBP6-mediated JUNB degradation as a critical mechanism contributing to chromatin disorganization and vascular dysfunction in diabetes.
Methods:
Chromatin topology in diabetic endothelium was profiled using H3K27ac HiChIP, ChIP-seq, ATAC-seq, and RNA-seq in both diabetic mouse models and human endothelial cells. JUNB overexpression and RBBP6 knockdown were performed to assess their roles in chromatin remodeling and endothelial function. Rapid immunoprecipitation mass spectrometry (RIME), co-immunoprecipitation, and ubiquitination assays were conducted to elucidate the post-translational regulation of JUNB by RBBP6.
Results:
Our analyses revealed that disruption of JUNB-centric chromatin topology is a key feature of diabetic endothelial cells. Mechanistically, hyperglycemia activates RBBP6-mediated ubiquitination and degradation of JUNB, resulting in a widespread loss of enhancer-promoter interactions critical for maintaining endothelial homeostasis. Furthermore, JUNB overexpression or RBBP6 knockdown restored enhancer-promoter interactions in gene programs essential for endothelial functions. Notably, RBBP6 knockdown recovered endothelium-dependent relaxation of aorta and ameliorated hindlimb ischemia in diabetic mice.
Conclusions:
Our work not only establishes 3D genome disorganization as a hallmark of diabetic endothelium but also reveals the RBBP6-JUNB axis as a potential therapeutic target for vascular complications. By linking metabolic dysregulation to chromatin-based mechanisms of gene control, this study opens new avenues for developing targeted interventions to preserve vascular health in diabetes.