@article{tarasow_kellogg_holley_nieuwlandt_tarasow_eaton_2004, title={The effect of mutation on RNA Diels-Alderases}, volume={126}, ISSN={["0002-7863"]}, DOI={10.1021/ja0494149}, abstractNote={Chemical mutagenesis of a previously reported RNA Diels-Alderase (DA22) was followed by in vitro selection based on [4 + 2] catalysis. New mutated families of RNA Diels-Alderases closely related in sequence space were obtained. The mutated Diels-Alderases selected showed significant improvements in catalytic efficiency (k(cat)/K(m)) as compared to the original DA22. The improvement in catalytic activity was primarily due to a decrease in K(m), but modest increases in k(cat) were also observed. The increase in catalytic activity of these new Diels-Alderases was found not to negatively affect their dienophile specificity. Surprisingly, one of the most active Diels-Alderases (DAM 40), a subtle sequence mutant of DA22, was found to show a new metal dependence and could function with Ni(2+) as the only transition-metal ion. Truncation experiments of DA22 showed that the region shown to be hypervariable at the 3'-end of the structure could be deleted without a significant decrease in the relative rate of Diels-Alder catalysis.}, number={38}, journal={JOURNAL OF THE AMERICAN CHEMICAL SOCIETY}, author={Tarasow, TM and Kellogg, E and Holley, BL and Nieuwlandt, D and Tarasow, SL and Eaton, BE}, year={2004}, month={Sep}, pages={11843–11851} }
 @article{goralska_dackor_holley_mcgahan_2003, title={Alpha lipoic acid changes iron uptake and storage in lens epithelial cells}, volume={76}, ISSN={["0014-4835"]}, DOI={10.1016/S0014-4835(02)00307-X}, abstractNote={Alpha lipoic acid (LA) is a cofactor in mitochondrial dehydrogenase complexes. Previous studies have shown that when administered exogenously LA has antioxidant properties, which include free radical scavenging, metal chelation and regeneration of other antioxidants. The cells convert LA into dihydroplipoic acid (DHLA), which in the presence of iron can act as a prooxidant. In vitro DHLA reduces Fe+3 to Fe+2 and removes iron from ferritin, increasing the risk of Fe catalyzed free radical formation. In the present study we examined the in vivo effects of lipoic acid treatment on Fe metabolism in cultured lens epithelial cells, and found that LA decreases Fe uptake from transferrin, increases Fe deposition into ferritin and increases the concentration of this protein. When administered together with ascorbic acid, lipoic acid changes the characteristic heavy to light chain ratio of ferritin makeup. The decreased Fe uptake and increased storage diminishes the size of the cytosolic highly reactive Fe pool (LIP). These changes are associated with increased cell resistance to H2O2 challenge. Therefore, LA may reduce the risk of Fe induced oxidative damage and also might be useful as a treatment of Fe overload.}, number={2}, journal={EXPERIMENTAL EYE RESEARCH}, author={Goralska, M and Dackor, R and Holley, B and McGahan, MC}, year={2003}, month={Feb}, pages={241–248} }
 @article{goralska_holley_mcgahan_2003, title={Identification of a mechanism by which lens epithelial cells limit accumulation of overexpressed ferritin H-chain}, volume={278}, ISSN={["0021-9258"]}, DOI={10.1074/jbc.M305827200}, abstractNote={The primary cultures of canine lens epithelial cells were transiently transfected with cDNAs for dog ferritin H- or L-chains in order to study differential expression of these chains. By using chain-specific antibodies, we determined that at 48 h after transfection overexpression of L-chain was much higher (9-fold over control) than that of H-chain (1.7-fold). We discovered that differentially transfected cells secrete overexpressed chains as homopolymeric ferritin into the media. Forty-eight hours after transfection accumulation of H-ferritin in the media was much higher (3-fold) than that of L-ferritin. This resulted in lowering of the concentration of H-chain in the cytosol. Co-transfection of cells with both H- and L-chain cDNAs increased the intracellular levels of H-chain and eliminated secretion of H-ferritin to the media. We concluded that lens epithelial cells differentially regulate concentration of both ferritin chains in the cytosol. The overexpressed L-chain accumulated in the cytosol as predominantly homopolymeric L-ferritin. This is in contrast to H-chain, which is removed to the media unless there is an L-chain available to form heteropolymeric ferritin. These data indicate that the inability of cells to more strictly control cytosolic levels of L-chain may augment its accumulation in lenses of humans with hereditary hyperferritinemia cataract syndrome, which is caused by overexpression of L-chain due to mutation in the regulatory element in the untranslated region of the mRNA of the chain.}, number={44}, journal={JOURNAL OF BIOLOGICAL CHEMISTRY}, author={Goralska, M and Holley, BL and McGahan, MC}, year={2003}, month={Oct}, pages={42920–42926} }
 @article{goralska_holley_mcgahan_2001, title={Overexpression of H- and L-ferritin subunits in lens epithelial cells: Fe metabolism and cellular response to UVB irradiation}, volume={42}, number={8}, journal={Investigative Ophthalmology and Visual Science}, author={Goralska, M. and Holley, B. L. and McGahan, M. C.}, year={2001}, pages={1721–1727} }
 @article{goralska_holley_mcgahan_2000, title={The effects of Tempol on ferritin synthesis and Fe metabolism in lens epithelial cells}, volume={1497}, ISSN={["0167-4889"]}, DOI={10.1016/S0167-4889(00)00038-0}, abstractNote={The nitroxide, Tempol, can protect tissue from oxidative damage by removing superoxide and by oxidizing Fe(II) to Fe(III), thus decreasing formation of the hydroxyl radical. However, long-term exposure to Tempol can damage cells. The oxidation of Fe could have profound effects on Fe metabolism in cells, yet this has not been previously studied. In the present investigation, the effects of Tempol on the synthesis of the Fe storage protein, ferritin, and its ability to store Fe were studied in cultured lens epithelial cells (LEC). In addition, the effects of short- and long-term Tempol treatment on the resistance of LEC to oxidative stress were determined. Tempol had a clear dose-dependent inhibitory effect on ferritin synthesis noted at 6 h. By 20 h, ferritin synthesis returned toward normal levels. However, Fe incorporation into ferritin was decreased by almost 90% by the highest dose of Tempol, even at the 20-h time point. The decrease in Fe incorporation into ferritin was accompanied by a significant increase in the LMW pool of Fe. After short-term (4 h) treatment with Tempol, LEC were protected against the toxic effects of tertiary butyl hydroperoxide. However, after longer term treatment (20 h), Tempol itself had a toxic effect and did not afford protection. Indeed, at the higher doses, Tempol significantly reduced the ability of the cells to withstand oxidative stress. The redistribution of Fe within the cell after 20 h of Tempol treatment appears to render the cells more vulnerable to oxidative stress. The deleterious effects of Tempol on LEC are likely due to its effects on Fe metabolism, perhaps by reducing the availability of Fe for incorporation into ferritin and Fe-dependent enzymes as well as enlarging a low molecular weight pool of Fe which may be capable of catalyzing damaging free radical reactions.}, number={1}, journal={BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH}, author={Goralska, M and Holley, B and McGahan, MC}, year={2000}, month={Jun}, pages={51–60} }