Analysis of the TID-I and TID-L Splice Variants' Expression Profile under In Vitro Differentiation of Human Mesenchymal Bone Marrow Cells into Osteoblasts

Bone formation is a complex process regulated by a variety of pathways that are not yet fully understood. One of the proteins involved in multiple osteogenic pathways is TID (DNAJA3). The aim of this work was to study the association of TID with osteogenesis. Therefore, the expression profiles of the splice variants ( , ) and their protein products were analyzed during the proliferation and differentiation of bone marrow mesenchymal stromal cells (B-MSCs) into osteoblasts. As the reference, the hFOB1.19 cell line was used. The phenotype of B-MSCs was confirmed by the presence of CD73, CD90, and CD105 surface antigens on ~97% of cells. The osteoblast phenotype was confirmed by increased alkaline phosphatase activity, calcium deposition, and expression of ALPL and SPP1. The effect of silencing the gene on the expression of and was also investigated. The TID proteins and the expression of splice variants were detected. After differentiation, the expression of and increased 5-fold and 3.7-fold, respectively, while their silencing resulted in increased expression of . Three days after transfection, the expression of increased 7.6-fold and 5.6-fold in B-MSCs and differentiating cells, respectively. Our preliminary study demonstrated that the expression of and changes under differentiation of B-MSCs into osteoblasts and may influence the expression of . However, for better understanding the functional association of these results with the relevant osteogenic pathways, further studies are needed.