Muscle defects due to perturbed somite segmentation contribute to late adult scoliosis

Zebrafish: an important model for understanding scoliosis

Scoliosis is a common spinal deformity that considerably affects the physical and psychological health of patients. Studies have shown that genetic factors play an important role in scoliosis. However, its etiopathogenesis remain unclear, partially because of the genetic heterogeneity of scoliosis and the lack of appropriate model systems. Recently, the development of efficient gene editing methods and high-throughput sequencing technology has made it possible to explore the underlying pathological mechanisms of scoliosis. Owing to their susceptibility for developing scoliosis and high genetic homology with human, zebrafish are increasingly being used as a model for scoliosis in developmental biology, genetics, and clinical medicine. Here, we summarize the recent advances in scoliosis research on zebrafish and discuss the prospects of using zebrafish as a scoliosis model.

Hnrnpul1 controls transcription, splicing, and modulates skeletal and limb development in vivo

Mutations in RNA-binding proteins can lead to pleiotropic phenotypes including craniofacial, skeletal, limb, and neurological symptoms. Heterogeneous nuclear ribonucleoproteins (hnRNPs) are involved in nucleic acid binding, transcription, and splicing through direct binding to DNA and RNA, or through interaction with other proteins in the spliceosome. We show a developmental role for Hnrnpul1 in zebrafish, resulting in reduced body and fin growth and missing bones. Defects in craniofacial tendon growth and adult-onset caudal scoliosis are also seen. We demonstrate a role for Hnrnpul1 in alternative splicing and transcriptional regulation using RNA-sequencing, particularly of genes involved in translation, ubiquitination, and DNA damage. Given its cross-species conservation and role in splicing, it would not be surprising if it had a role in human development. Whole-exome sequencing detected a homozygous frameshift variant in HNRNPUL1 in 2 siblings with congenital limb malformations, which is a candidate gene for their limb malformations. Zebrafish Hnrnpul1 mutants suggest an important developmental role of hnRNPUL1 and provide motivation for exploring the potential conservation of ancient regulatory circuits involving hnRNPUL1 in human development.

Genetic animal models of scoliosis: A systematical review

Scoliosis is a complex disease with undetermined pathogenesis and has a strong relationship with genetics. Models of scoliosis in animals have been established for better comprehending its pathogenesis and treatment. In this review, we searched all the genetic animal models with body curvature in databases, and reviewed the related genes and scoliosis types. Meanwhile, we also summarized the pathogenesis of scoliosis reported so far. Summarizing the positive phenotypic animal models contributes to a better understanding on the pathogenesis of scoliosis and facilitates the selection of experimental models when a possible pathogenic factor is concerned.

Notch Signaling Regulates Muscle Stem Cell Homeostasis and Regeneration in a Teleost Fish

Muscle regeneration is mediated by the activity of resident muscle satellite cells (muSCs) that express Pax7. In mouse Notch signaling regulates muSCs during quiescence and promotes muSC proliferation in regeneration. It is unclear if these roles of Notch in regulating muSC biology are conserved across vertebrates or are a mammalian specific feature. We have therefore investigated the role of Notch in regulating muSC homeostasis and regeneration in a teleost fish, the zebrafish. We have also tested whether muSCs show differential sensitivity to Notch during myotome development. In an absence of injury Notch is important for preventing muSC proliferation at the vertical myoseptum. In contrast, Notch signaling promotes proliferation and prevents differentiation in the context of injury. Notch is required for the proliferative response to injury at early and later larval stages, suggesting it plays a similar role in regulating muSCs at developing and adult stages. Our results reveal a conserved role for Notch signaling in regulating muSCs under homeostasis and for promoting proliferation during regeneration in teleost fish.