Truncated recombinant Jagged1 fused with human IgG1 Fc activates Notch target genes in human periodontal ligament cells.

OBJECTIVE: Jagged1, a Notch ligand, is essential for osteogenic differentiation in human periodontal ligament cells (hPDLs) by interacting with Notch2 to induce osteogenic markers, alkaline phosphatase activity, and mineral deposition. However, its large size hampers absorption and distribution of biomaterials. This study aimed to identify the critical region of Jagged1 necessary for its interaction with Notch2 to create a truncated version that retains osteogenic activity but with improved delivery characteristics.

METHODS: Truncated versions of Jagged1 were designed by deleting C-terminal regions, focusing on the importance of the N-terminal domain. Both truncated and full-length Jagged1 were fused with human IgG1 Fc (Jagged1-Fc) and expressed in Chinese hamster ovary cells. hPDLs treated with these constructs were analyzed for Notch target gene expression using real-time PCR. Mineral deposition was assessed using alizarin red S staining.

RESULTS: Both truncated and full-length Jagged1-Fc increased the expression of Notch target genes (Hes1, Hey1, and ALP) in hPDLs, indicating successful activation of Notch signaling. However, only the full-length Jagged1-Fc enhanced mineral deposition, while the truncated version did not.

CONCLUSIONS: Full-length Jagged1-Fc is required for mineral deposition and complete osteogenic differentiation in hPDLs. The truncated versions, while capable of activating Notch signaling, are ineffective in promoting mineralization, underscoring the importance of the entire protein for clinical applications in bone regeneration.