Cell adhesion in zebrafish myogenesis: Distribution of intermediate filaments, microfilaments, intracellular adhesion structures and extracellular matrix

Abstract

To overcome the limitations of in vitro studies, we have been studying myogenesis in situ in zebrafish embryos, at a sub-cellular level. While in previous works we focused on myofibrillogenesis and some aspects of adhesion structures, here we describe in more detail cell adhesion structures and interactions among cytoskeletal components, membrane and extracellular matrix during zebrafish muscle development. We studied the intermediate filaments, and we describe the full range of desmin distribution in zebrafish development, from perinuclear to striated, until its deposition around the intersomite septa of older somites. This adhesion structure, positive for desmin and actin, has not been previously observed in myogenesis in vitro. We also show that actin is initially located in the intersomite septum region whereas it is confined to the myofibrils later on. While actin localization changes during development, the adhesion complex proteins vinculin, paxillin, talin, dystrophin, laminin and fibronectin always appear exclusively at the intersomite septa, and appear to be co-distributed, even though the extracellular proteins accumulates before the intracellular ones. Contrary to the adhesion proteins, that are continuously distributed, desmin and sarcomeric actin form triangular aggregates among the septa and the cytoskeleton. We studied the cytoskeletal linker plectin as well, and we show that it has a distribution similar to desmin and not to actin. We conclude that the in situ adhesion structures differ from their in vitro counterparts, and that the actual zebrafish embryo myogenesis is quite different than that which occurs in in vitro systems.

Hanging on for the ride: Adhesion to the extracellular matrix mediates cellular responses in skeletal muscle morphogenesis and disease

“…We and others have shown that the ECM changes during muscle development and regeneration in both zebrafish and mouse (Bajanca et al, 2004; Bentzinger et al, 2013; Costa et al, 2008; Deries et al, 2012; Marques and Thorsteinsdóttir, 2013; Snow and Henry, 2009). These dynamic changes allow the muscle ECM to be tuned to the morphogenetic or adaptive responses that generate and maintain this amazing structure.…”

Development of the zebrafish myoseptum with emphasis on the myotendinous junction

“…The second linkage system contains the main collagen receptors, the integrins, which are associated to actin microfilaments on the cytoplasm side of sarcolemma and ECM molecules on the extracellular side. Several focal adhesion molecules including vinculin, FAK, paxillin and talin have been identified in zebrafish (Henry et al 2001;Crawford et al 2003;Costa et al 2008;Câmara-Pereira et al 2009). The molecular composition of the myoseptal matrix also remains elusive.…”

Alterations in zebrafish development induced by simvastatin: Comprehensive morphological and physiological study, focusing on muscle

“…Therefore, we, and others, have been using zebrafish embryos (Danio rerio) to study myogenesis. [2][3][4] These embryos are transparent and undergo rapid development ex utero, allowing detailed structural analysis of muscle development as well as physiological studies both in situ and in vivo. We have previously characterized the sequence of expression and distribution of cytoskeletal, adhesion, and extracellular matrix proteins during myogenesis in this model.…”