Knockdown of hspg2 is associated with abnormal mandibular joint formation and neural crest cell dysfunction in zebrafish

Abstract

AbstractBackgroundHeparan sulfate proteoglycan 2 (HSPG2)encodes for perlecan, a large proteoglycan that plays an important role in cartilage formation, cell adhesion, and basement membrane stability. Mutations inHSPG2have been associated with Schwartz-Jampel Syndrome (SJS) and Dyssegmental Dysplasia Silverman-Handmaker Type (DDSH), two disorders characterized by skeletal abnormalities. These data indicate a function forHSPG2in cartilage development/maintenance. However, the mechanisms in whichHSPG2regulates cartilage development are not completely understood. Here, we explored the relationship between this gene and craniofacial development through morpholino-mediated knockdown ofhspg2using zebrafish.ResultsKnockdown ofhspg2resulted in abnormal development of the mandibular jaw joint at 5 days post fertilization (DPF). We surmised that defects in mandible development were a consequence of neural crest cell (NCC) dysfunction, as these multipotent progenitors produce the cartilage of the head. Early NCC development was normal in morphant animals as measured by distal-less homeobox 2a (dlx2a)and SRY-box transcription factor 10 (sox10)expression at 1 DPF. However, subsequent analysis at later stages of development (4 DPF) revealed a decrease in the number of Sox10+and Collagen, type II, alpha 1a (Col2a1a)+cells within the mandibular jaw joint region of morphants relative to random control injected embryos. Concurrently, morphants showed a decreased expression ofnkx3.2,a marker of jaw joint formation, at 4 DPF.ConclusionsCollectively, these data suggest a complex role forhspg2in jaw joint formation and late stage NCC differentiation.