Differential expression of heme oxygenase-1 in cultured cortical neurons and astrocytes determined by the aid of a new heme oxygenase antibody. Response to oxidative stress.
Heme oxygenase exists as two isoenzymes designated heme oxygenase-1 (HO-1) and heme oxygenase-2 (HO-2). HO-2 is made constitutively in many cell types whereas HO-1 is a stress protein inducible by heat, heavy metals, ultraviolet irradiation, and oxidative stress. Recombinant rat HO-1 was expressed in bacteria and antiserum designated HO-1713 was raised against the purified protein. HO-1713 detected recombinant rat HO-1 and recombinant rat HO-2. In rat tissues it detected HO-1 and a second, unidentified band designated HO-L (heme oxygenase-like immunoreactivity) which was not HO-2. Cultured rat cortical neurons and forebrain astrocytes were exposed to hydrogen peroxide (0.14-0.7 micromolar for 30 or 60 min). Neurons which contained little detectable HO-1 and which were sensitive to hydrogen peroxide at the high end of the dose curve failed to induce HO-1 by Western blot analysis. In contrast, cultured rat forebrain astrocytes which contained HO-1 under normal culture conditions and which were resistant to injury by hydrogen peroxide, increased their content of immunoreactive HO-1 by 7-fold within 3 h after exposure. Our results support a protective role for HO-1 in oxidative injury and suggest that the relative inability of neurons to increase HO-1 after oxidative stress may contribute to their selective vulnerability vis-a-vis astrocytes. They also suggest that differential expression of heme oxygenase in studies utilizing CNS cultures may alter normal cell physiology and cell survival.
Dwyer
B E
BE
Molecular Neurobiology Laboratory, Department of Veterans Affairs Medical Center, Sepulveda, CA 91343, USA.
Nishimura
R N
RN
Lu
S Y
SY
D000906:Antibodies / Q000276:immunology*; D001253:Astrocytes / Q000201:enzymology / Q000378:metabolism*; D001345:Autoradiography; D015153:Blotting, Western; D002478:Cells, Cultured; D004586:Electrophoresis; D006419:Heme Oxygenase (Decyclizing) / Q000096:biosynthesis* / Q000235:genetics; D007150:Immunohistochemistry; D009474:Neurons / Q000201:enzymology / Q000378:metabolism; D018384:Oxidative Stress / Q000502:physiology*; D016133:Polymerase Chain Reaction; D011994:Recombinant Proteins
D000906:Antibodies; D011994:Recombinant Proteins; D006419:Heme Oxygenase (Decyclizing)