Fig. 1: Ectopic Pitx2 expression in the developing delB/delB SAN. | Nature Communications

Fig. 1: Ectopic Pitx2 expression in the developing delB/delB SAN.

From: PITX2 dosage-dependent changes in pacemaker cell state underlie sinus node dysfunction and atrial arrhythmias

Fig. 1

a In situ hybridization reveals absence of Pitx2 expression at E10.5 in the wild-type SAN (n = 3) and early ectopic Pitx2 expression in the SAN alongside maintained expression in the LA, prPV, and AVC (arrow) delB/delB heart (n = 4). Scale is 200 μm. b Immunostaining shows absence of PITX2+ nuclei in the ISL1+ wild-type SAN (n = 3) and PITX2+ nuclei alongside ISL1+ nuclei in the delB/delB SAN (n = 3) at E10.5. Scale is 100 μm. Insets show co-localization of ISL1 and PITX2 expression in the delB/delB SAN. Scale is 10 μm. c In situ hybridization shows that Pitx2 clearly demarcates the left from the RA and is normally absent from the SAN (n = 2). Scale is 200 μm. Pitx2 is ectopically expressed in the delB/+ (n = 3) and delB/delB (n = 2) SAN (outlined) at E12.5. Scale is 100 μm. d Immunostaining shows that PITX2 expression is normally restricted to the SVC and LA and absent from the ISL1+ SAN (n = 3). Ectopic PITX2 expression in the delB/+ (n = 3) and delB/delB (n = 7) SAN (outlined) is heterogeneous and coincides with a loss of ISL1 expression by the end of gestation at E17.5. Scale is 200 μm and 100 μm. SAN sinus node, RA right atrium, LA left atrium, prPV primordial pulmonary vein, AVC atrioventricular canal, E embryonic day, RV right ventricle, LV left ventricle, SCV superior caval vein.

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