Affiliations: Department of Food Science and Biotechnology, National
Chung Hsing University, Taiwan
Note: [] Address for correspondence: Professor M.-L. Hu, Department of
Food Science and Biotechnology, National Chung Hsing University, 250 Kuo-Kuang
Road, Taichung, 402, Taiwan. Tel./Fax: +886 4 22812363; E-mail:
[email protected]
Abstract: Homocysteine (Hcy), S-adenosylhomocysteine (SAH) and adenosine (Ado)
are methionine metabolism intermediates that may act synergistically in certain
disease. In this study, we examined whether HCy, SAH and Ado may
synergistically induce neuronal apoptosis of BV-2 microglial cells. We found
that an incubation of BV-2 cells with 1 mM Hcy, 1 μM SAH and 100 μM Ado
(SAH + Hcy + Ado) led to marked apoptosis
of BV-2 cells, as evidenced by several markers of apoptosis. A synergistic
effect of SAH + Hcy + Ado on apoptosis
(2.55-fold, P < 0.05) was obtained, as calculated using the
data of Annexin V-positive cells. This combination markedly induced
intracellular levels of reactive oxygen species (ROS) starting at 6 h and
significantly decreased the mitochondrial potential starting at 12 h. The
combination significantly elevated caspase-9 and caspase-3 activities at 24 and
48 h. The combination also induced hypomethylation (at 24 and 48 h), as
indicated by significantly decreased 5-methyldeoxycytidine levels and SAM/SAH
ratios. Pre-incubation of cells with α-tocopherol
(30 μM) reduced the increase of ROS (at 6 h) and
significantly restored cell viability (at 24 and 48~h) in the SAH
+ Hcy + Ado group. Overall, the present
study demonstrates that SAH, Hcy and Ado synergistically induce BV-2 apoptosis,
possibly by generation of ROS and induction of intracellular
hypomethylation.
