Apoptosis and epicardial contributions act as complementary factors in remodeling of the atrioventricular canal myocardium and atrioventricular conduction patterns in the embryonic chick heart

0499622 - FGÚ 2019 RIV US eng J - Článek v odborném periodiku
Steijn, R. V. - Sedmera, David - Blom, N. A. - Jongbloed, M. - Kvasilová, A. - Naňka, O.
Apoptosis and epicardial contributions act as complementary factors in remodeling of the atrioventricular canal myocardium and atrioventricular conduction patterns in the embryonic chick heart.
Developmental Dynamics. Roč. 247, č. 9 (2018), s. 1033-1042. ISSN 1058-8388. E-ISSN 1097-0177
Grant CEP: GA ČR(CZ) GA13-12412S; GA ČR(CZ) GA16-02972S
Institucionální podpora: RVO:67985823
Klíčová slova: ventricular pre-excitation * chick embryo * optical mapping * atrioventricular junction * apoptosis * epicardial inhibition
Obor OECD: Cell biology
Impakt faktor: 2.852, rok: 2018

Background: During heart development, it has been hypothesized that apoptosis of atrioventricular canal myocardium and replacement by fibrous tissue derived from the epicardium are imperative to develop a mature atrioventricular conduction. To test this, apoptosis was blocked using an established caspase inhibitor and epicardial growth was delayed using the experimental epicardial inhibition model, both in chick embryonic hearts. Results: Chicken embryonic hearts were either treated with the peptide caspase inhibitor zVAD-fmk by intrapericardial injection in ovo (ED4) or underwent epicardial inhibition (ED2.5). Spontaneously beating embryonic hearts isolated (ED7-ED8) were then stained with voltage-sensitive dye Di-4-ANEPPS and imaged at 0.5-1 kHz. Apoptotic cells were quantified (ED5-ED7) by whole-mount LysoTracker Red and anti-active caspase 3 staining. zVAD-treated hearts showed a significantly increased proportion of immature (base to apex) activation patterns at ED8, including ventricular activation originating from the right atrioventricular junction, a pattern never observed in control hearts. zVAD-treated hearts showed decreased numbers of apoptotic cells in the atrioventricular canal myocardium at ED7. Hearts with delayed epicardial outgrowth showed also increased immature activation patterns at ED7.5 and ED8.5. However, the ventricular activation always originated from the left atrioventricular junction. Histological examination showed no changes in apoptosis rates, but a diminished presence of atrioventricular sulcus tissue compared with controls. Conclusions: Apoptosis in the atrioventricular canal myocardium and controlled replacement of this myocardium by epicardially derived HCN4-/Trop1- sulcus tissue are essential determinants of mature ventricular activation pattern. Disruption can lead to persistence of accessory atrioventricular connections, forming a morphological substrate for ventricular pre-excitation.
Trvalý link: http://hdl.handle.net/11104/0291854