title: A review on hemeoxygenase-2: focus on cellular protection and oxygen response.
abstract: Hemeoxygenase (HO) system is responsible for cellular heme degradation to biliverdin, iron, and carbon monoxide. Two isoforms have been reported to date. Homologous HO-1 and HO-2 are microsomal proteins with more than 45% residue identity, share a similar fold and catalyze the same reaction. However, important differences between isoforms also exist. HO-1 isoform has been extensively studied mainly by its ability to respond to cellular stresses such as hemin, nitric oxide donors, oxidative damage, hypoxia, hyperthermia, and heavy metals, between others. On the contrary, due to its apparently constitutive nature, HO-2 has been less studied. Nevertheless, its abundance in tissues such as testis, endothelial cells, and particularly in brain, has pointed the relevance of HO-2 function. HO-2 presents particular characteristics that made it a unique protein in the HO system. Since attractive results on HO-2 have been arisen in later years, we focused this review in the second isoform. We summarize information on gene description, protein structure, and catalytic activity of HO-2 and particular facts such as its cellular impact and activity regulation. Finally, we call attention on the role of HO-2 in oxygen sensing, discussing proposed hypothesis on heme binding motifs and redox/thiol switches that participate in oxygen sensing as well as evidences of HO-2 response to hypoxia.
authors.affiliation: Laboratorio de Patología Vascular Cerebral, Instituto Nacional de Neurología y Neurocirugía Manuel Velasco Suárez, 14269 Delegación Tlalpan, DF, Mexico.
authors.forename: Jorge
authors.initials: J
authors.lastname: Muñoz-Sánchez
authors.affiliation: Laboratorio de Patología Vascular Cerebral, Instituto Nacional de Neurología y Neurocirugía Manuel Velasco Suárez, 14269 Delegación Tlalpan, DF, Mexico.
authors.forename: María Elena
authors.initials: ME
authors.lastname: Chánez-Cárdenas
mesh_terms: D002248:Carbon Monoxide / Q000378:metabolism; D003577:Cytochrome P-450 Enzyme System / Q000378:metabolism; D006418:Heme / Q000378:metabolism; D006419:Heme Oxygenase (Decyclizing) / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D000860:Hypoxia; D051036:Large-Conductance Calcium-Activated Potassium Channels / Q000378:metabolism; D020030:Nitric Oxide Donors / Q000378:metabolism; D010100:Oxygen / Q000378:metabolism*; D020033:Protein Isoforms / Q000737:chemistry / Q000378:metabolism
chemical_list: D051036:Large-Conductance Calcium-Activated Potassium Channels; D020030:Nitric Oxide Donors; D020033:Protein Isoforms; D006418:Heme; D002248:Carbon Monoxide; D003577:Cytochrome P-450 Enzyme System; D006419:Heme Oxygenase (Decyclizing); C105245:heme oxygenase-2; D010100:Oxygen