Mahin D. Maines

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The heme oxygenase (HO) system consists of two forms identified to date: the oxidative stress-inducible protein HO-1 (HSP32) and the constitutive isozyme HO-2. These proteins, which are different gene products, have little in common in primary structure, regulation, or tissue distribution. Both, however, catalyze oxidation of heme to biologically active(More)
In biological systems oxidation of heme is carried out by two isozymes of the microsomal heme oxygenase, HO-1 and HO-2. HO-1 is the commonly known heme oxygenase, the activity of which can be induced by up to 100-fold in response to a wide variety of stimuli (metals, heme, hormones, etc.). HO-2 was only recently discovered, and the isozyme appears to be(More)
Degradation of heme requires its conversion to biliverdin (BV) by heme oxygenase, followed by reduction of BV to the free-radical quencher bilirubin (BR) by biliverdin reductase (BVR). It is now recognized that human BVR (hBVR) is a dual-specificity kinase (Ser/Thr and Tyr) upstream activator of the insulin/insulin growth factor-1 (IGF-1) and(More)
The present report describes, for the first time, the identification of two constitutive forms of heme oxygenase, designated as HO-1 and HO-2, in rat liver microsomal fractions. HO-1 was purified to homogeneity and exhibited a specific activity of up to 4000 nmol of bilirubin/mg of protein/h. HO-2 was partially purified to a specific activity of 250 nmol of(More)
We describe here the tyrosine kinase activity of human biliverdin reductase (BVR) and its potential role in the insulin-signaling pathway. BVR is both a substrate for insulin receptor (IR) tyrosine kinase (IRK) activity and a kinase for serine phosphorylation of IR substrate 1 (IRS-1). Our previous studies have revealed serine/threonine kinase activity of(More)
Biliverdin reductase (BVR) functions in cell signaling through three distinct tracks: a dual-specificity kinase that functions in the insulin receptor/MAPK pathways (25, 29, 51); a bzip-type transcription factor for ATF-2/CREB and HO-1 regulation (1, 25); and a reductase that catalyzes the conversion of biliverdin to bilirubin (27). These, together with the(More)
Activation of the MEK/ERK/Elk-signaling cascade is a mechanism for relaying mitogenic and stress stimuli for gene activation. MEK1 is the proximate kinase for activation of ERK1/2, and nuclear targeting of ERK1/2 is obligatory for Elk1 transcriptional activity. Human biliverdin reductase (hBVR) is a recently described Ser/Thr/Tyr kinase in the MAPK(More)
Recently, we have reported on the presence of two forms of heme oxygenase in rat liver and testis microsomes, referred to as HO-1 and HO-2 (M. D. Maines, G. M. Trakshel, and R. K. Kutty (1986) J. Biol. Chem. 261, 411-419; G. M. Trakshel, R. K. Kutty, and M. D. Maines (1986) J. Biol. Chem. 261, 11131-11137). Although the two forms differed in several(More)
Heme oxygenase-1 (HO-1, HSP32) is an early gene that is responsive to an array of pathological conditions including, but not limited to, hypoxia and cerebral ischemia. HO-1 cleaves the heme molecule and produces carbon monoxide (CO) and biliverdin (an antioxidant) and is essential for iron homeostasis. The purpose of this study was to investigate, using(More)