Identification of a Dual Leucine Zipper Kinase involved in rat fracture repair

Complete cDNA sequence was obtained for a gene found to be expressed al a high level during fracture healing in the rat. Comparison of the amino acid sequence (deduced from the cDNA sequence) with known sequences showed 99% identify with mouse Dual Leucine Zipper Kinase (mDLK) and 96% identity with human Zipper Protein Kinase (hZPK). Relative quantitation by RT-PCR indicates abundant expression of this gene in cultured chondrocytes, growth plate and brain tissue. Further, regulated expression of this gene has been observed during fracture healing in rat femur fracture model; maximum gene expression in this model appears to coincide with chondrogenesis and bone formation. Since DLK has been shown to function in the mitogen activated signaling (MAP) pathway, these results provide the first evidence for the involvement of this signaling pathway in fracture healing. (C) 1996 Academic Press, Inc.