Signalling by growth differentiation factor 6 (GDF6/BMP13) has been implicated in the development and maintenance of healthy NP cell phenotypes and GDF6 mutations are associated with defective vertebral segmentation in Klippel-Feil syndrome. GDF6 may thus represent a promising biologic for treatment of IVD degeneration. This study aimed to investigate the effect of GDF6 in human NP cells and critical signal transduction pathways involved. BMP receptor expression profile of non-degenerate and degenerate human NP cells was determined through western blot, immunofluorescence and qPCR. Phosphorylation statuses of Smad1/5/9 and non-canonical p38 MAPK and Erk1/2 were assessed in the presence/absence of pathway blockers. NP marker and matrix degrading enzyme gene expression was determined by qPCR following GDF6 stimulation. Glycosaminoglycan and collagen production were assessed through DMMB-assay and histochemical staining.Background
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