Abstract 207: Angiotensin -II (Ang-II) Induces Endoplasmic Reticulum (ER) Stress-mediated Overproduction of Mitochondrial Reactive Oxygen Species (mROS) and Alterations in Mitochondria-associated Membrane (MAM) in Neural Cells
ER stress and mROS are identified as key mediators of Ang-II-induced neurogenic hypertension. Although ER and mitochondria are linked both structurally and functionally, the interplay between these two organelles in neural cells and in the subfornical organ (SFO), a key forebrain region in Ang-II hypertension, is unknown. Previously we reported that Ang-II causes mitochondrial fragmentation in murine SFO neurons. Here we tested the hypothesis that Ang II-induced mitochondrial dysfunction is mediated by ER stress and disruption of the MAM. Neuro-2A cells were incubated with Ang-II (300 nM, 24 h) and real-time PCR was performed to examine expression of key molecular markers of MAM (n=3-5). Dynamin related peptide 1 (drp1), a MAM marker and mitochondrial fission protein, was increased in the presence of Ang-II (1.77±0.17-fold vehicle, p<0.05).This effect was blocked when cells were co-treated with the chemical ER stress inhibitor TUDCA (0.77 ± 0.27 fold vs. Ang-II; p<0.05). Ang-II also increased the expression of phosphofurin acidic cluster sorting protein 2 (pacs2, another MAM marker) and the co-administration of TUDCA was able to block this effect (Ang-II: 1.5 ± 0.02-fold vs. vehicle; TUDCA+Ang-II: 0.9 ± 0.03 fold vs. Ang-II; p<0.05). Ang-II-induced mROS production, measured by MitoSox Red dye (n=11-15), was decreased in the presence of TUDCA (12 ± 4% increase from vehicle compared to a 58 ± 2% increase with Ang-II alone ; p<0.05). BD-1047, a chemical disruptor of MAM, also prevented the Ang-II-induced increase in MitoSox fluorescence (9.6 ± 0.2 % vs. Ang-II alone; p<0.05). Furthermore, when MDivi-1, a selective drp-1 blocker, was added, a similar blockade of mROS production was observed (11.9 ± 0.8 %; p < 0.05) In dissociated SFO cells from adult male C57Bl/6 mice (n=8-23), Ang-II-induced mROS production (12.9 ± 2% increase from vehicle, p< 0.05) was blocked by TUDCA (0.8 ± 0.01%, p<0.05) and by losartan (2.2 ± 1.6%, p<0.05). These data demonstrate that induction of ER stress by Ang-II leads to mitochondrial fragmentation mediated by MAM disruption, which then results in mROS overproduction. Collectively, our data suggest a novel role for ER-MAM interaction in Ang-II-mediated hypertension.
Author Disclosures: P. Sarkar: None. U. Patel: None. G. Wang: None. C. Iadecola: None. A.L. Mark: None. R.L. Davisson: None.
- © 2014 by American Heart Association, Inc.