Joseph Fomusi Ndisang Pages 1318 - 1327 ( 10 )
Although recent studies have underscored the role of the heme-oxygenase (HO) inducer hemin, on insulin-signaling and glucose metabolism, the underlying mechanisms are not completely understood. In this study, two-dimensional-gel electrophoresis, massspectrometry and MSACOT-analyses were used to identify and characterize novel proteins modulated by hemin in spontaneoushypertensive rat (SHR), a model of essential hypertension with insulin resistance/impaired glucose metabolism. In addition, the effects of hemin on endothelin-1 (ET-1), protein-tyrosine-phosphatase-1B (PTP-1B), atrial-natriuretic-peptide (ANP) and its surrogate-marker urinary cGMP, and inflammatory cytokines including TNF-α, IL-6 and IL-1β were investigated. </p> <p> In hemin-treated SHR, several proteins related to oxidative-stress and metabolism were modulated. Particularly, hemin enhanced aldolase- B, fumarylacetoacetate hydrolase, purine-nucleoside phosphorylase, adenosine-kinase, argininosuccinate synthetase and carbonic anhydrase-3 all of which are enzymes involved in glucose/energy metabolism and pH homeostasis. Similarly, hemin potentiated antioxidant pathways including, NADP(+)-dependant isocitrate-dehydrogenase, catalase, glutathione-S-transferase-Yb1 and hsp70, a pleiotropic agent that regulates protein-folding, oxidative/pro-inflammatory events. Hemin also increased enzymes implicated in cell-growth such as the nitrilase-protein-family, but reduced betaine-homocysteine methyltransferase, an enzyme associated with insulin resistance and dysfunctional glucose metabolism. Furthermore, hemin increased ANP and its surrogate marker, urinary cGMP, but reduced ET-1, PTP-1B, TNF-α, IL-6, IL-1β, whereas the HO-inhibitor, chromium-mesoporphyrin abolished the effects. </p> <p> The potentiation of ANP, urinary-cGMP, aldolade-B, fumarylacetoacetate hydrolase, purine-nucleoside phosphorylase, adenosine-kinase, argininosuccinate synthetase, carbonic anhydrase-3, hsp70 and the corresponding reduction of betaine-homocysteine methyltransferase, PTP-1B, TNF-α, IL-6, IL-1β, and ET-1 may be responsible for the improved glucose metabolism in hemin-treated animals. </p> <p> Collectively, these findings underscore the pleiotropic effects of the HO-system in cellular homeostasis with important roles in metabolism and defence.
Heme oxygenase, essential hypertension, spontaneously hypertensive rats, Tumor necrosis factor alpha, Interleukin.
Department of Physiology, College of Medicine, University of Saskatchewan, 107 Wiggins Road, Saskatoon, SK, Canada S7N 5E5.