The orthopedic characterization of cfap298tm304 mutants validate zebrafish to faithfully model human AIS

Abstract

Cerebrospinal fluid (CSF) circulation relies on the beating of motile cilia projecting in the lumen of the brain and spinal cord cavities Mutations in genes involved in cilia motility disturb cerebrospinal fluid circulation and result in scoliosis-like deformities of the spine in juvenile zebrafish. However, these defects in spine alignment have not been validated with clinical criteria used to diagnose adolescent idiopathic scoliosis (AIS). The aim of this study was to describe, using orthopaedic criteria the spinal deformities of a zebrafish mutant model of AIS targeting a gene involved in cilia polarity and motility, cfap298tm304. The zebrafish mutant line cfap298tm304, exhibiting alteration of CSF flow due to defective cilia motility, was raised to the juvenile stage. The analysis of mutant animals was based on micro-computed tomography (micro-CT), which was conducted in a QUANTUM FX CALIPER, with a 59 µm-30 mm protocol. 63% of the cfap298tm304 zebrafish analyzed presented a three-dimensional deformity of the spine, that was evolutive during the juvenile phase, more frequent in females, with a right convexity, a rotational component and involving at least one dislocation. We confirm here that cfap298tm304 scoliotic individuals display a typical AIS phenotype, with orthopedic criteria mirroring patient’s diagnosis.

Urotensin II-Related Peptides, Urp1 and Urp2, Control Zebrafish Spine Morphology

“…This demonstrates that adolescent-onset curves in Urotensin-deficient mutants occur in the absence of vertebral patterning or structural defects. Additionally, we parsed our phenotypic data for sex since spinal curves often show sex bias in severity in humans (Cheng et al, 2015), something which has been recapitulated in some zebrafish spinal curve models (Marie-Hardy et al, 2021). However, in both urp1 ΔP ;urp2 ΔP and uts2r3 b1436 mutants, we found no significant differences in curve penetrance or severity between males and females (Figs.…”

“…These curves were argued to model an adolescent idiopathic scoliosis (AIS)-like condition (Fig. 4A-B and Movie S8; Grimes et al, 2016; Marie-Hardy et al, 2021). Importantly, both urp1 and urp2 transcripts were significantly downregulated in cfap298 tm304 mutants (Fig.…”

“…Mutants with defective motile cilia failed to undergo axial straightening during embryogenesis and so developed a misshapen early embryonic body axis called "curly tail down" (CTD; Brand et al, 1996). If rescued during this early stage, mutants went on to develop three-dimensional spinal curves that recapitulated some features of idiopathic scoliosis, including adolescent-stage onset and absence of vertebral structural defects (Grimes et al, 2016;Marie-Hardy et al, 2021;Wang et al, 2022). Precisely how motile cilia and CSF flow maintain spine morphology during growth is not understood, but it is known that during early larval stages cilia motility is essential for the assembly of the Reissner fiber (RF), an ex t ra c e l l u l a r t h rea d -l i ke s t r u c t u re c o m p o s e d predominantly of the large glycoprotein SCOspondin (encoded by sspo) which sits in the CSF in brain ventricles and the central canal (Cantaut-Belarif et al, 2018;Rodriguez et al, 1998).…”

Extending the Horizon of Homology Detection with Coevolution-based Structure Prediction

“…CFAP298 (also known as C21ORF59) plays a role in motile cilia within outer dynein arm assembly. 64 , 65 , 66 Its homology and domain architecture were unclear, except for a predicted coiled-coil and a C-terminal domain of unknown function. A predicted contact map indicated likely interactions between α-helices or β-strands, but yielded no further clues ( Figure 5 ).…”

Prevalence of POC5 Coding Variants in French-Canadian and British AIS Cohort

“…POC5 is a centriolar protein that is essential for cell cycle progression, cilia elongation [ 15 ], centriole elongation, and maturation. Since the identification of the POC5 gene, a ciliary gene that is strongly associated with AIS, the ciliary pathway has been thoroughly investigated and has revealed promising results [ 12 , 15 , 16 , 17 , 18 ].…”