Fig. 4: AREG drives circadian-dependent cardioprotection.
From: BMAL1–HIF2A heterodimer modulates circadian variations of myocardial injury
a, Schematic of myocardial injury and cardiac function assessment in Areg−/− mice and WT mice subjected to IRI at ZT8 or ZT20. b, Heart slices were stained with Evan’s blue and TTC after 2 h reperfusion. Scale bar, 1 mm. c, The AAR as a percentage of the LV. d, The infarct size as a percentage of the AAR. n = 7 mice per group per timepoint. e, Serum troponin I levels. n = 8 mice per group per timepoint. f,g, Cardiac function on day 14 after MI was determined using STE. f, The EF and GLS. g, B-mode images with 2D longitudinal strain. 1, anterior base; 2, anterior middle; 3, anterior apex; 4, posterior apex; 5, posterior middle; 6, posterior base. n = 8 mice per group per timepoint. h,i, TUNEL staining in the border zone on day 1 after MI (h; scale bar, 25 μm) and quantification (i). White arrows point out TUNEL-positive (green) cardiomyocyte (red) nuclei (blue). n = 4 mice per group per timepoint. j, Schematic of the cardiac injury and function assessment in AREG-treated or vehicle (veh.)-treated mice subjected to IRI at ZT8 or ZT20. Treatment was initiated at reperfusion and continued daily for 3 days. k,l, AREG protein in the AAR (k) with quantification (l). n = 3 mice per group per timepoint. m–p, Evan’s blue- and TTC-stained heart slices (m, scale bar, 1 mm), the AAR as a percentage of the LV (n), the infarct size as a percentage of the AAR (o) and serum troponin I levels (p) after 2 h reperfusion. n = 7 mice per group per timepoint. q,r, Cardiac function on day 14 after MI. q, The EF, FS and GLS. r, LV 3D images with six-segment longitudinal strain. n = 7 mice per group per timepoint. s,t, TUNEL staining in the border zone. The percentage of TUNEL-positive cells (s) and representative images (t) are shown. White arrows indicate TUNEL-positive (green) cardiomyocyte (red) nuclei (blue). Scale bar, 25 μm. n = 5 (veh., ZT8), n = 4 (veh., ZT20), n = 5 (AREG, ZT8) and n = 5 (AREG, ZT20). All data are mean ± s.e.m. For c–f,i,l,n–q and s, statistical analysis was performed using two‐way ANOVA. The diagrams in a and j were created using BioRender.
