TY - JOUR TI - Twisting of the zebrafish heart tube during cardiac looping is a tbx5-dependent and tissue-intrinsic process AU - Tessadori, Federico AU - Tsingos, Erika AU - Colizzi, Enrico Sandro AU - Kruse, Fabian AU - van den Brink, Susanne C AU - van den Boogaard, Malou AU - Christoffels, Vincent M AU - Merks, Roeland MH AU - Bakkers, Jeroen A2 - Stainier, Didier YR A2 - Meilhac, Sigolène M A2 - Furthauer, Maximilian VL - 10 PY - 2021 DA - 2021/08/10 SP - e61733 C1 - eLife 2021;10:e61733 DO - 10.7554/eLife.61733 UR - https://doi.org/10.7554/eLife.61733 AB - Organ laterality refers to the left-right asymmetry in disposition and conformation of internal organs and is established during embryogenesis. The heart is the first organ to display visible left-right asymmetries through its left-sided positioning and rightward looping. Here, we present a new zebrafish loss-of-function allele for tbx5a, which displays defective rightward cardiac looping morphogenesis. By mapping individual cardiomyocyte behavior during cardiac looping, we establish that ventricular and atrial cardiomyocytes rearrange in distinct directions. As a consequence, the cardiac chambers twist around the atrioventricular canal resulting in torsion of the heart tube, which is compromised in tbx5a mutants. Pharmacological treatment and ex vivo culture establishes that the cardiac twisting depends on intrinsic mechanisms and is independent from cardiac growth. Furthermore, genetic experiments indicate that looping requires proper tissue patterning. We conclude that cardiac looping involves twisting of the chambers around the atrioventricular canal, which requires correct tissue patterning by Tbx5a. KW - heart KW - T-box KW - asymmetry KW - chiral KW - laterality KW - cell tracking JF - eLife SN - 2050-084X PB - eLife Sciences Publications, Ltd ER -