Macrophage FOXK2 Promotes Cardiac Repair in Myocardial Infarction with Stress Hyperglycemia [RNA-Seq]

Methods

To ascertain the clinical significance of FOXK2, peripheral blood mononuclear cells (PBMCs) were collected from non-diabetic patients with MI and FOXK2 expression was quantified. We also generated Cx3cr1CreFoxk2flox/flox mice with conditional deletion of FOXK2 in the macrophages to assess the function of macrophage FOXK2 in post-MI cardiac repair. Liquid chromatography-tandem mass spectrometry (LC-MS/MS), RNA-sequencing (RNA-seq), CUT&Tag assays, in vitro O-GlcNAcylation assay, biolayer interferometry (BLI) analysis, molecular docking analysis and functional studies were used to dissect the molecular mechanism of FOXK2 O-GlcNAcylation-regulating cardiac repair post-MI with SHG.

Results: We found significantly reduced FOXK2 levels in PBMCs from MI patients with SHG and in cardiac macrophages from hyperglycemic mice following MI. Loss of macrophage FOXK2 exacerbated cardiac injury, with mechanistic studies revealing that FOXK2 is glycosylated at T552 by O-GlcNAc transferase under high-glucose conditions, promoting its degradation via the ubiquitin-proteasome pathway. Mass spectrometry and functional assays demonstrated that the FOXK2T552A variant resisted hyperglycemia-induced degradation.

Combined CUT&Tag and RNA-seq analyses showed that FOXK2 suppresses interleukin-6 (IL-6)/signal transducer and activator of transcription 3 (STAT3) signaling by repressing H3K27 acetylation, thereby aiding cardiac repair. Conclusions: Together, these findings establish FOXK2 as a critical regulator of cardiac repair and suggest that preventing excessive FOXK2 O-GlcNAcylation could be a promising therapeutic strategy for improving outcomes in MI patients with SHG.

Keywords: Stress Hyperglycemia; Myocardial Infarction; Macrophage; FOXK2; O-GlcNAcylation