The gelatinases, matrix metalloproteinases 2 and 9, play individual roles in skeleton development

The gelatinases, a subgroup of the matrix metalloproteinases (MMPs) superfamily are composed of two members; MMP2 and MMP9. They are known to degrade gelatin among other components of the extracellular matrix. Recently, the two gelatinases were found to be necessary for neural crest cell migration and to compensate for each other loss in these cells. To characterize their involvement in the skeletal system, and to better reveal their individual or common roles, we have generated double knockout (dKO) mice, lacking both MMP2 and MMP9. The transcriptome of calvaria, growth plate and femoral cortical bone of P21 C57BL/6J WT, MMP2-/-, MMP9-/- and dKO mice was analyzed by bulk RNA-Seq. Cortical bone, growth plate and calvarial bone samples were collected from 5-7 P21 females of all four genotypes: WT, MMP2-/-, MMP9-/- and dKO. Cortical bone samples were taken from femur bone and were cleaned from all adjacent tissues (muscle, tendon and ligaments) and the diaphyseal bone marrow was removed by washing it out with ultra-pure water, using a small needle and syringe. Growth plate samples were collected from cleaned tibiae and for the calvarial samples the right/left frontal bone was taken. The samples were individually flash frozen in liquid nitrogen and were subjected to manually pulverization. Total RNA was extracted and purified using TRI reagent (Sigma, USA) according to the manufacturer’s protocol.