Dong-Dong Yuan

Publications of Dong-Dong Yuan

• Berberine potentizes apoptosis induced by X-rays irradiation probably through modulation of gap junctions.

  Authors: Bing Liu, Qin Wang, Dong-dong Yuan, Xiao-ting Hong, Liang Tao

  Chinese medical journal. 04/2011; 124(8):1221-8.

  Clinical combination of some traditional Chinese medical herbs, including berberine, with irradiation is demonstrated to improve efficacy of tumor radiotherapy, yet the mechanisms for such effectClinical combination of some traditional Chinese medical herbs, including berberine, with irradiation is demonstrated to improve efficacy of tumor radiotherapy, yet the mechanisms for such effect remain largely unknown. The present study investigated the effect of berberine on apoptosis induced by X-rays irradiation and the relation between this effect and gap junction intercellular communication (GJIC). The role of gap junctions in the modulation of X-rays irradiation-induced apoptosis was explored by manipulation of connexin (Cx) expression, and gap junction function, using oleamide, a GJIC inhibitor, and berberine. In transfected HeLa cells, Cx32 expression increased apoptosis induced by X-rays irradiation, while inhibition of gap junction by oleamide reduced the irradiation responses, indicating the dependence of X-rays irradiation-induced apoptosis on GJIC. Berberine, at the concentrations without cytotoxicity, enhanced apoptosis induced by irradiation only in the presence of functional gap junctions. These results suggest that berberine potentizes cell apoptosis induced by X-rays irradiation, probably through enhancement of gap junction activity.

• The effects of 2-aminoethoxydiphenyl borate and diphenylboronic anhydride on gap junctions composed of Connexin43 in TM₄ sertoli cells.

  Authors: Yan Yang, Ming-Hui Cao, Qin Wang, Dong-Dong Yuan, Li Li, Liang Tao

  Biological & pharmaceutical bulletin. 01/2011; 34(9):1390-7.

  2-Aminoethoxydiphenyl borate (2-APB) has recently been demonstrated to inhibit gap junction (GJ) channels, whereas the underlying mechanisms are still unknown. Using mouse TM₄ Sertoli cell which2-Aminoethoxydiphenyl borate (2-APB) has recently been demonstrated to inhibit gap junction (GJ) channels, whereas the underlying mechanisms are still unknown. Using mouse TM₄ Sertoli cell which expresses connexin43 (Cx43), we explored the effects of 2-APB and its analogues on dye-coupling through junctional channels formed by Cx43 and on expression of Cx43. Exposure of the cells to 2-APB (1-50 µM) and one of its analogues diphenylboronic anhydride (DPBA) (1-30 µM) for 4 h leads to a significant decrease in dye coupling of GJ in a concentration-dependent manner. The inhibitory effects of 2-APB and DPBA are reversible since decreased GJ coupling resumes after the two compounds are washed out. The disfunction of GJ induced by 2-APB and DPBA is associated with a decrease in total amount of Cx43 protein and number of GJs on the cell membrane. 2-APB and DPBA do not alter Cx43 phosphorylation state and the level of Cx43 mRNA expression. The loss of Cx43 protein is prevented by either lysosomal or proteasomal inhibitor, suggesting that the decrease in Cx43 results from a 2-APB or DPBA-enhanced degradation of Cx43. The present results indicate that 2-APB and DPBA inhibit GJ communication through decreasing Cx43 expression in TM₄ cells.