Impact of silencing HO-2 on EC-SOD and the mitochondrial signaling pathway.
The contribution of heme oxygenase HO-2, the primary source of bilirubin and carbon monoxide (CO) under physiological conditions, to the regulation of vascular function has remained largely unexplored. Using siRNA HO-2, we examined the effect of suppressed levels of HO-2 on vascular antioxidant and survival proteins. In vivo HO-2 siRNA treatment decreased the basal levels of EC-SOD, pAKT proteins (serine-473 and threonine-308), without changing Akt protein expression. HO-2 siRNA treatment increased 3-nitrotyrosine (3-NT) and apoptotic signaling kinase-1 (ASK-1) (P < 0.01). HO activity was decreased by the use of siRNA HO-2. We extended these studies to the mitochondria, examining for the presence of HO-1 and its role in the regulation of pro- and anti-apoptotic proteins. HO activity was increased by the administration of CoPP resulting in the translocation of HO-1 into the mitochondria, mainly to the inner face of the mitochondrial inner membrane. These findings suggest that HO-2 is critical in the maintenance of heme homeostasis and also the regulation of apoptosis by controlling levels of EC-SOD, Akt, 3-NT, and ASK-1. In addition, localization of HO-1 in the mitochondrial compartment plays a critical role in mitochondria-mediated apoptosis.
Turkseven
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Department of Pharmacology, New York Medical College, Valhalla, NY, USA.
Drummond
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Rezzani
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Rodella
L
L
Quan
S
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Ikehara
S
S
Abraham
N G
NG
D000818:Animals; D017209:Apoptosis / Q000502:physiology; D015153:Blotting, Western; D006419:Heme Oxygenase (Decyclizing) / Q000235:genetics* / Q000378:metabolism / Q000502:physiology; D008928:Mitochondria / Q000378:metabolism*; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism; D034622:RNA Interference; D034741:RNA, Small Interfering / Q000235:genetics; D051381:Rats; D017207:Rats, Sprague-Dawley; D015398:Signal Transduction / Q000235:genetics / Q000502:physiology; D013482:Superoxide Dismutase / Q000378:metabolism*; D014443:Tyrosine / Q000031:analogs & derivatives / Q000378:metabolism; D050995:Voltage-Dependent Anion Channel 1 / Q000378:metabolism
D034741:RNA, Small Interfering; C494764:Vdac1 protein, rat; C002744:3-nitrotyrosine; D014443:Tyrosine; D006419:Heme Oxygenase (Decyclizing); C105245:heme oxygenase-2; D013482:Superoxide Dismutase; D050995:Voltage-Dependent Anion Channel 1; D051057:Proto-Oncogene Proteins c-akt