Abstract P133: Mitochondrial- Dependent Apoptosis in Arterial Remodeling: Link to Hypertension
Hyperhomocysteinemia (HHcy) has been observed to promote hypertension through endothelial dysfunction and vascular remodeling, but the mechanisms are unclear. Previously, we showed that elevated homocysteine levels disturbed mitochondrial dynamics facilitating excessive mitochondrial fission with consequent endothelial cell loss and collagen deposition in the mesenteric artery. In the present study, we hypothesize that HHcy-induced excessive mitochondrial fission promotes mitochondrial apoptosis through Bax activation that up- regulates downstream apoptotic proteases (Caspase-9, Caspase-3), causing endothelial cell loss and arterial remodeling that predispose to hypertension. To test this hypothesis, we used 12 week old C57BL/6J mice (WT) as a control; Cystathionine-β-synthase deficient mice (CBS+/-) with genetic HHcy; C3H/HeJ (C3H) mice, that are resistant to oxidative stress and CBS+/-/C3H mice. Blood pressure and vascular reactivity measurements, western blotting (Caspase-9 and Caspase-3), q-PCR (Bax, Bcl-2), immunohistochemistry (cleaved Caspase-3) and TUNEL assay were used in this study. Blood pressure values were up-regulated in CBS+/- mice (diastolic: 118.4 ± 9.8 mmHg; systolic: 153.9 ± 12.7 mmHg; mean: 130 ± 10 mmHg) compared to WT mice (diastolic: 101 ± 15 mmHg; systolic: 139 ± 10 mmHg; mean: 113 ± 14 mmHg). Interestingly, blood pressure values were decreased in C3H mice (diastolic: 74.8 ± 6.5 mmHg; systolic: 118.6 ± 9 mmHg; mean: 89 ± 7 mmHg) compared to control (diastolic: 96 ± 7 mmHg; systolic: 143.4 ± 2.4 mmHg; mean: 111.4 ± 5.5 mmHg). q-PCR showed 11 fold up-regulation of Bax mRNA expression in the mesenteric artery of CBS+/- mice compared to control. Western Blotting validated two- fold increase of Caspase-9 and Caspase-3 protein expressions in the mesenteric artery of CBS+/- mice compared to WT mice. TUNEL assay further indicated the presence of DNA fragments in the mesenteric artery of CBS+/- mice. In conclusion, our data suggested that HHcy-induced mitochondrial fission promotes Bax activation followed by mitochondrial apoptosis with activation of downstream proteases (Caspase-9, Caspase-3), leading to endothelial cell loss and arterial remodeling that contributes to hypertension.
Author Disclosures: A. Familtseva: None. A. Kalani: None. P. Chaturvedi: None. N. Metreveli: None. S.C. Tyagi: None.
- © 2015 by American Heart Association, Inc.