Role of Zebrafish fhl1A in Satellite Cell and Skeletal Muscle Development

Abstract

Background: Four-and-a-half LIM domains protein 1 (FHL1) mutations are associated with human myopathies. However, the function of this protein in skeletal development remains unclear.Methods: Whole-mount in situ hybridization and embryo immunostaining were performed.Results: Zebrafish Fhl1A is the homologue of human FHL1. We showed that fhl1A knockdown causes defective skeletal muscle development, while injection with fhl1A mRNA largely recovered the muscle development in these fhl1A morphants. We also demonstrated that fhl1A knockdown decreases the number of satellite cells. This decrease in satellite cells and the emergence of skeletal muscle abnormalities were associated with alterations in the gene expression of myoD, pax7, mef2ca and skMLCK. We also demonstrated that fhl1A expression and retinoic acid (RA) signalling caused similar skeletal muscle development phenotypes. Moreover, when treated with exogenous RA, endogenous fhl1A expression in skeletal muscles was robust. When treated with DEAB, an RA signalling inhibitor which inhibits the activity of retinaldehyde dehydrogenase, fhl1A was downregulated.Conclusion: fhl1A functions as an activator in regulating the number of satellite cells and in skeletal muscle development. The role of fhl1A in skeletal myogenesis is regulated by RA signaling.

NMJ Analyser: a novel method to quantify neuromuscular junction morphology in zebrafish

“…The ability to perform high-resolution imaging in a living organism has revolutionized the field of biological research, and the zebrafish is playing a critical role in advancing our understanding of the underlying mechanisms of development and disease. Several studies have capitalized on the advantages of the zebrafish and provided important insights in motor axonal growth ( Myers et al 1986 , Chen et al 2012 , Sainath and Granato 2013 ), neuromuscular junction (NMJ) development ( Jing et al 2010 , Bailey et al 2019 ), synaptogenesis ( Jontes et al 2000 , Hutson and Chien 2002 , Panzer et al 2005 , Son et al 2020 ), muscle development ( Skobo et al 2014 , Dubińska-Magiera 2016 , Chen et al 2017 , Yin et al 2022 ), and in NMJ deficits underlying neuromuscular pathologies ( Patten et al 2017 , Butti et al 2021 , Lescouzères et al 2023 ). In the last few decades, the zebrafish has particularly emerged as a valuable tool in studying the pathogenesis and development of therapeutic interventions for various neuromuscular disorders ( Singh and Patten 2022 ).…”