ANGPTL2 and CP define complementary circadian-associated signals in atrial fibrillation: integrative transcriptomics and external validation.

INTRODUCTION

Atrial fibrillation (AF) develops through the interplay of electrical, structural, inflammatory, and metabolic remodeling. However, the circadian-associated molecular characteristics of the diseased human atrium remain incompletely understood.

METHODS

We integrated differential expression analysis, circadian gene intersection, weighted gene co-expression network analysis, and complementary feature selection algorithms in a discovery cohort. The prioritized candidate genes were subsequently validated using an independent atrial dataset, human atrial rhythmicity data, single-nucleus transcriptomics, and experimental evidence derived from human and mouse atrial tissues. We additionally performed cross-cohort drug repurposing screening and exploratory molecular docking.

RESULTS

ANGPTL2 and CP were identified as prioritized candidate genes associated with circadian rhythms. Both genes were consistently upregulated in fibrillating atria but exhibited distinct expression profiles: ANGPTL2 demonstrated stronger discriminatory power at the tissue level, whereas CP showed a larger but more heterogeneous expression alteration. Both genes displayed rhythmic expression patterns in human atrial appendage tissue and were predominantly enriched in vascular and stromal cell populations, establishing a link between temporal atrial biology and inflammatory-metabolic remodeling as well as copper-redox remodeling. The upregulation of their transcripts and proteins was further validated across independent human samples and an arrhythmia-prone mouse model. No compound met the prespecified multi-source criteria for cross-cohort drug repurposing. An independent exploratory analysis of clinically used antiarrhythmic drugs identified favorable molecular docking profiles for both target proteins.

DISCUSSION: ANGPTL2 and CP are externally validated circadian rhythm-associated candidate genes for atrial fibrillation (AF), and may yield experimentally testable candidate gene-drug pairs. However, these findings do not establish causal regulation by the circadian clock, direct molecular binding, or clinical therapeutic efficacy.