Inhibition of connexin 43 expression and function in cultured rat dental pulp cells by antisense oligonucleotide

Connexins are gap-junction proteins forming hexameric structures in the plasma membranes of adjacent cells, thereby creating intercellular channels. Connexin 43 (CX43) is expressed in pulp tissue. However, its function in dental pulp tissue has yet to be fully investigated. We have employed antisense oligonucleotides (AS) against rat CX43 to study the role of CX43 in dental pulp cells. Cultured dental pulp cells were treated with AS or sense (S) oligonucleotides. The number of cells in the AS-treated groups was approximately 1.3-fold that in the S-treated controls. Growth rates were significantly different between the AS- and S-treated groups at 48 h (P < 0.01). An alkaline phosphatase assay revealed that AS-treated pulp cells dramatically decreased at 48 h after AS incorporation, whereas S-treated pulp cells showed no marked changes. Western blot analysis revealed that heat-shock protein 25 was highly expressed in S-treated cells but was only weakly expressed in AS-treated cells at 48 h. Furthermore, AS-treated cells highly expressed CX45, whereas S-treated cells exhibited high expression of CX32. These results suggest that CX43 is involved in cell growth, mineralization, and differentiation to odontoblasts in rat pulp cells, and that CX43 plays the opposite role to that of CX45.