Localization, isolation and characterization of Mn-superoxide dismutase in bovine adrenocortical cells

Cloning of Mn-SOD gene and its mRNA expression difference and antioxidant enzyme activities under hypoxia stress of cobia Rachycentron canadum

BACKGROUND

Environmental hypoxia affects the survival and development of organisms. It is also an important environmental factor that leads to oxidative damage. Hypoxia is a condition in which tissues are deprived of oxygen; reoxygenation is the phenomenon in which hypoxic tissues are exposed to oxygen. Hypoxia-reoxygenation is vital in pathogenesis, where the production of reactive oxygen species and antioxidant disparity significantly contribute to disease progression, and it is one of the most common physiological stressors in the aquaculture industry.

METHODS AND RESULTS

In this study, the full length of complementary DNA (cDNA) of the manganese superoxide dismutase (Mn-SOD) gene of healthy cobia Rachycentron canadum was analysed using rapid amplification of cDNA ends. The real-time quantitative Polymerase Chain Reaction was used to measure the expression levels of Mn-SOD mRNAs in various tissues (heart, muscle, brain, liver, kidney, gill, intestine, and spleen). The 2^-ΔΔCT method was used to performed the expression analysis. The experimental data were analysed using SPSS ver. 19.0 ( https://spss.software.informer.com/19.0/ ). P < 0.05 and P < 0.01 were set as significant differences. The values were articulated as mean ± standard deviation. The Mn-SOD gene cDNA sequence was 1209 bp long, including a 684 bp open reading frame, 42 bp 5'UTR and 483 bp 3'UTR, encoding 227 amino acids. Under hypoxia-reoxygen stress, the expression of Mn-SOD in brain tissue was significantly lower than in the control group after 8 h of reoxygenation and higher than the control group after 24 h. Hypoxia and subsequent reoxygenation triggered a disturbance in antioxidant homeostasis, displayed in the modification of GPx expression/activity in the liver: GPx was improved.

CONCLUSIONS

These results provide valuable information on the role of Mn-SOD regulation in oxidative stress caused by hypoxia.

Primary structure and properties of Mn-superoxide dismutase from scallop adductor muscle

Manganese-superoxide dismutase was purified to homogeneity from scallop adductor muscle using DEAE-Sephacel, Buthyl-Cellulofine and Superdex 200 pg column chromatographies. The molecular weights of the purified enzyme were calculated to be 22,321.4 according to time-of-flight mass spectrometry, and to be approximately 95,000 and 93,000 on Superdex 200 pg column chromatography and non-denatured PAGE, respectively, and were calculated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis to be 24,000 and 25,000 in the absence and 25,000 in the presence of beta-mercaptoethanol. These findings suggested that the native enzyme is composed of four identical subunits. Other properties of scallop adductor muscle manganese-superoxide dismutase, including pH stability and heat stability, were also determined. We determined the partial amino acid sequences of purified manganese-superoxide dismutase using digestions by bromocyan and lysyl endopeptidase and also determined the manganese-superoxide dismutase cDNA structure. The amino acid sequence of the enzyme obtained using both methods showed homology to those of vertebrates such as human, bovine, chicken, Xenopus and zebrafish manganese-superoxide dismutases (64.91, 65.35, 64.47, 63.27 and 64.60%, respectively). We also predicted the 3D structure of scallop adductor muscle manganese-superoxide dismutase using molecular operating environment and compared its structure with those of other manganese-superoxide dismutases. The overall structure of scallop adductor muscle manganese-superoxide dismutase was very similar to those of other species, including human and Aspergillus.

Superoxide Dismutase in Human Adrenal and its Disorders: A Correlation with Development and Neoplastic Changes

In adrenal glands, oxidative free radicals are synthesized in the course of hormonal production, and enzyme superoxide dismutase (SOD) is considered to scavenge these harmful superoxide radicals and, subsequently, to protect the cells. We studied immunohistochemical localization of Mn (manganese)-SOD and Cu,Zn (copper-zinc)-SOD in human adrenal and its disorders from fetus to adult obtained from autopsy or surgery in order to examine the possible biological significance of these two enzymes. In fetal adrenal (n = 4), Cu,Zn-SOD and Mn-SOD were detected only in the fetal cortex. In adrenal glands from children (n = 21) to adults (n = 15), Mn-SOD immunoreactivity was exclusively detected in adrenal medulla, whereas Cu,Zn-SOD immunoreactivity was present only in adrenocortical parenchymal cells, weakly in the zona glomerulosa, and markedly in the zona reticularis. There were no differences in relative immunointensity and/or patterns of immunolocalization of these two SODs among different age groups. Both Cu,Zn-SOD and Mn-SOD immunoreactivity were detected in compact tumor cells of adrenocortical adenoma (n = 16). Marked immunoreactivity of both Cu,Zn-SOD and Mn-SOD was detected in adrenocortical carcinoma (n = 11) and pheochromocytoma (n = 5). These results indicate that Cu,Zn-SOD and Mu-SOD may play different roles as a scavenger or antioxidants in normal human adrenal glands, i.e., Cu,Zn-SOD as a scavenger of toxic superoxide radicals generated during steroidogenesis and Mn-SOD during catecholamine production. Cu,Zn-SOD and Mn-SOD immunoreactivities detected in adrenal neoplasms are also considered to represent altered expression of these enzymes associated with neoplastic transformation, as reported in other human malignancies.