Expression of Notch-related genes in mesenchymal progenitor cell, Kusa-A1

Objective: To investigate the expression of Notch-related genes in mouse mesenchymal progenitor cell Kusa-A1 and analyze the possible role of Notch pathway in osteogenic differentiation. Methods: Kusa-A1 cells were cultured under normal or mineralization-inducing condition. Total RNA was isolated at day 0, 1, 3, 5 after confluence. Real-time PCR was used to detect the expression of Delta1, Jagged1, Notch1, CBF1, HES1 genes. Expression of osteopontin (OPN) was also examined. Results: Under normal culture condition, OPN expression was slightly down-regulated and level of Notch-related genes remained unchanged or showed slight down-regulation. After addition of L-ascorbic acid-2-phosphate and &beta-glycerophosphate, which are known to induce differentiation in osteogenic cells, OPN expression was up-regulated but expression of Delta1, Jagged1, Notch1 and HES1 all showed striking down-regulation. Interestingly, CBF1 expression exhibited slight up-regulation. Conclusion: Notch pathway is involved and may exert a suppression role in the differentiation of osteogenic cells. However, CBF1, transcriptional mediator of Notch signaling, may have a positive effect on osteogenic differentiation.