RNA in polysomes is an inhibitor of manganese superoxide dismutase RNA-binding protein activity.
A redox-sensitive protein in rat lung binds to the 3'-untranslated region (3'-UTR) of manganese superoxide dismutase (Mn-SOD) mRNA; the activity of this Mn-SOD RNA-binding protein (Mn-SOD-BP) is greater in 12,000-g supernatant fractions (S12) from neonates than in S12 from adults (H. Fazzone, A. Wangner, and L. B. Clerch. J. Clin. Invest. 92: 1278-1281, 1993). To determine the mechanism underlying this developmental difference, lung subcellular fractions were tested for their effect on Mn-SOD-BP activity. Protein in the 130,000-g supernatant (S130) of lung extracts bound the 3'-UTR. However, the developmental difference in binding was not present in S130. The 130,000-g pellet (P130) did not bind the 3'-UTR; rather, it contained an inhibitor of Mn-SOD-BP activity. Addition of P130 to S130 decreased RNA binding in a dose-dependent manner. Furthermore, adult P130 was a more potent inhibitor of RNA-binding activity than neonatal P130. These data indicate that the developmental difference in Mn-SOD-BP activity is due, in part, to an inhibitor in P130. Biochemical characterization revealed that the inhibitor is an RNA that may participate in the posttranscriptional control of Mn-SOD gene expression.
Chung
D J
DJ
Department of Physiology, Georgetown University School of Medicine, Washington, District of Columbia 20007, USA.
Clerch
L B
LB
D000375:Aging / Q000378:metabolism; D000818:Animals; D000831:Animals, Newborn / Q000254:growth & development / Q000378:metabolism; D002498:Centrifugation; D008168:Lung / Q000737:chemistry; D011132:Polyribosomes / Q000378:metabolism*; D012313:RNA / Q000502:physiology*; D016601:RNA-Binding Proteins / Q000037:antagonists & inhibitors*; D051381:Rats; D017207:Rats, Sprague-Dawley; D013482:Superoxide Dismutase / Q000235:genetics*; D014020:Tissue Extracts / Q000378:metabolism
D016601:RNA-Binding Proteins; D014020:Tissue Extracts; D012313:RNA; D013482:Superoxide Dismutase