Osteoblast populations and bone extracellular matrix proteins during skeletal development in zebrafish.

Understanding osteoblast differentiation and their function in bone matrix deposition and mineralization is central to the comprehension of bone development and of various bone pathologies. It is crucial to not only follow the expression of some landmark transcription factors or ECM proteins, but to also investigate the status of signaling pathways and factors regulating these processes. This can only be achieved by assessing the entire transcriptome of these cells.
We employed developing Tg(sp7:gfp-cr) zebrafish larvae to study the osteoblast transcriptome by isolating the entire osteoblast population at 4dpf, focusing on the possible existence of specific subpopulations. RNA-seq. Analysis revealed two populations at this stage and the differentially expressed gene list that showed genes related to bone and cartilage development. Further, GO term analysis gave us hits very specific to bone extracellular matrix, skeletal development, cartilage and bone specific genes, transcription factors and Calcium regulating hormones etc. to name a few.
The expression and function of specific genes of bone extracellular matrix, revealed by these analyses, were investigated using mutant lines and state of the art technologies. Thereafter, characterized for bone and cartilage staining’s at various stages of development. Taken together, these different approaches should allow us to better understand the function of the different genes and the regulatory circuits that are involved in skeletal differentiation, morphogenesis and mineralization, specifically in a non-mammalian vertebrate, but potentially also in humans.