Angiotensin II-mediated posttranslational modification of nNOS in the PVN of rats with CHF: role for PIN.
نویسندگان
چکیده
An increased sympathetic drive is an adverse characteristic in chronic heart failure (CHF). The protein expression of neuronal nitric oxide synthase (nNOS)- and hence nitric oxide (NO)-mediated sympathoinhibition is reduced in the paraventricular nucleus (PVN) of rats with CHF. However, the molecular mechanism(s) of nNOS downregulation remain(s) unclear. The aim of the study was to reveal the underlying molecular mechanism for the downregulation of nNOS in the PVN of CHF rats. Sprague-Dawley rats with CHF (6-8 wk after coronary artery ligation) demonstrated decreased nNOS dimer/monomer ratio (42%), with a concomitant increase in the expression of PIN (a protein inhibitor of nNOS known to dissociate nNOS dimers into monomers) by 47% in the PVN. Similarly, PIN expression is increased in a neuronal cell line (NG108) treated with angiotensin II (ANG II). Furthermore, there is an increased accumulation of high-molecular-weight nNOS-ubiquitin (nNOS-Ub) conjugates in the PVN of CHF rats (29%). ANG II treatment in NG108 cells in the presence of a proteasome inhibitor, lactacystin, also leads to a 69% increase in accumulation of nNOS-Ub conjugates immunoprecipitated by an antiubiquitin antibody. There is an ANG II-driven, PIN-mediated decrease in the dimeric catalytically active nNOS in the PVN, due to ubiquitin-dependent proteolytic degradation in CHF. Our results show a novel intermediary mechanism that leads to decreased levels of active nNOS in the PVN, involved in subsequent reduction in sympathoinhibition during CHF, offering a new target for the treatment of CHF and other cardiovascular diseases.
منابع مشابه
Decreased nNOS in the PVN leads to increased sympathoexcitation in chronic heart failure: role for CAPON and Ang II.
AIMS Previously, we showed an enhanced excitatory (N-methyl d-aspartate receptor-NR(1)) and decreased inhibitory neuronal nitric oxide (NO) synthase (nNOS) influence within the paraventricular nucleus (PVN) of rats with chronic heart failure (CHF). Although NR(1) and nNOS are normally linked, they can be disconnected by nNOS sequestering with nNOS-associated protein (CAPON). The aim of this stu...
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ورودعنوان ژورنال:
- American journal of physiology. Heart and circulatory physiology
دوره 305 6 شماره
صفحات -
تاریخ انتشار 2013