Tenascin in bone morphogenesis: Expression by osteoblasts and cell type-specific expression of splice variants

Abstract

The extracellular matrix glycoprotein, tenascin, is associated in vivo with mesenchyme undergoing osteogenesis and chondrogenesis, but is absent from mature bone and cartilage matrix. The expression of tenascin by osteoblastic cells in vitro has been investigated by immunoblotting and immunocytochemistry. Tenascin was secreted into the medium and deposited in the matrix by human and rat osteoblast-like cell lines, as well as by primary osteoblast-enriched cultures from chick embryo calvarial bones. In primary osteoblastenriched cultures, extracellular tenascin was found only in cell aggregates expressing the osteoblast marker alkaline phosphatase. Chicken osteoblast cultures synthesized almo..