Fig. 4: sspodmh4/+ IVDs exhibit collagenous ECM damage and matrix remodelling.
a, b Schematic representing the normal structure and organization of zebrafish IVDs at 21 dpf (10 mm SL) in the sagittal (a) and transverse (b) planes. VB vertebra body, NV notochord vacuole, NS notochord sheath cell, CE collagen type II and elastin matrix, DC dense collagen type I matrix, CF collagen type I bundle fiber, NP nucleus pulposus, IVL intervertebral ligament. This schematic is an original image created by Xu, R. (2025) with Tayasui Sketches. c Schematic depicting the mechanism by which collagen-hybridizing peptide (CHP, green probe) integrates into open regions (yellow stars) of collagen fibril triple helices (purple) to report on collagen ECM damage and remodelling. Created in BioRender. Ciruna, B. (2025) https://BioRender.com/7k495f0. d–g Confocal images of CHP-stained vertebral and IVD segments at 21 dpf (10 mm SL). d, e CHP staining in wildtype animals demonstrates normal remodelling of the collagen ECM matrix within the NP and AF, as seen in sagittal (d, N = 12, n = 12; scale bar = 20 μm) and transverse (e, N = 13, n = 13; scale bar = 10 μm) planes. f, g In contrast, sspodmh4/+ mutant animals exhibit ectopic CHP staining within NP (arrowheads) and IVL (arrows) structures, as seen in sagittal (f, N = 12, n = 12, scale bar = 20 μm) and transverse (g, N = 15, n = 15, scale bar = 10 μm) planes, indicating significant damage to the collagenous ECM matrix of sspodmh4/+ mutant IVDs.
