Confirmation of the assignment of the human SODS gene to chromosome 21q22

MIF homolog d-dopachrome tautomerase (D-DT/MIF-2) does not inhibit accumulation and toxicity of misfolded SOD1

Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disease characterized by loss of upper and lower motor neurons. About 20% of familial ALS cases are caused by dominant mutations in SOD1. It has been suggested that toxicity of mutant SOD1 results from its misfolding, however, it is unclear why misfolded SOD1 accumulates within specific tissues. We have demonstrated that macrophage migration inhibitory factor (MIF), a multifunctional protein with cytokine/chemokine and chaperone-like activity, inhibits the accumulation and aggregation of misfolded SOD1. Although MIF homolog, D-dopachrome tautomerase (D-DT/MIF-2), shares structural and genetic similarities with MIF, its biological function is not well understood. In the current study, we investigated, for the first time, the mechanism of action of D-DT in a model of ALS. We show that D-DT inhibits mutant SOD1 amyloid aggregation in vitro, promoting the formation of amorphous aggregates. Moreover, we report that D-DT interacts with mutant SOD1, but does not inhibit misfolded mutant SOD1 accumulation and toxicity in neuronal cells. Finally, we show that D-DT is expressed mainly in liver and kidney, with extremely low expression in brain and spinal cord of adult mice. Our findings contribute to better understanding of D-DT versus MIF function in the context of ALS.

High-level expression of a sika deer (Cervus nippon) Cu/Zn superoxide dismutase in Pichia pastoris and its characterization

Production of a sika deer Cu/Zn-SOD was achieved in Pichia pastoris after the reconstituted expression vector pPIC9K was transformed into the strain GS115. By employing Saccharomyces cerevisiae secretion signal peptide (α-factor) under the regulation of the methanol-inducible promoter of the gene of alcohol oxidase 1 (AOX1), sika deer Cu/Zn-SOD with a molecular mass of 16kDa was expressed while recombinant sika deer Cu/Zn-SOD with an activity of 3500U/mL was obtained from a 5L bioreactor. After two successive steps of chromatography on DEAE-650C and Superdex75, recombinant sika deer Cu/Zn-SOD was obtained with 13.8% yield, 14.5-fold purification, and a specific activity of 3447U/mg. Its optimum temperature and optimum pH were 40°C and 7.0, respectively.

Red cell superoxide dismutase, glutathione peroxidase and catalase in Down syndrome patients with and without manifestations of Alzheimer disease

The activities of red blood cell enzymes that scavenge the superoxide radical and hydrogen peroxide were measured in severely to profoundly retarded adult Down syndrome (DS) patients with and without manifestations of Alzheimer disease (AD), and control individuals matched for sex, age, and time of blood sampling. Cu,Zn superoxide dismutase (SOD-1) and glutathione peroxidase (GSHPx) activities were significantly elevated (1.39-fold and 1.24-fold, respectively) in DS individuals without AD. When an adjustment was made for the SOD gene dosage effect, DS patients with AD manifestations had significantly lower SOD levels than the matched control individuals. In contrast, DS patients with and without AD had a similar elevation in GSHPx (an adaptive phenomenon). The mean catalase (CAT) activity was no different in DS and control individuals; however, in a paired regression analysis, DS patients without AD had marginally lower CAT activity than control individuals, whereas DS patients with AD had slightly but not significantly higher CAT activity. Thus, AD manifestations in this DS population are associated with changes in the red cell oxygen scavenging processes.

Trisomy 21q223 and Down's phenotype correlation evidenced by in situ hybridization

Two cases of trisomy 21q223 with the Down's phenotype were analysed by in situ hybridization with specific probes previously located in the sub-bands 21q221 (SOD-A) and 21q223 (BCEI and COL6A). These studies give evidence that the clinical picture of Down's syndrome is at least to a great extent correlated with trisomy for the 21q223 band.

Submicroscopic duplication of chromosome 21 and trisomy 21 phenotype (Down syndrome)

A patient with the phenotype of trisomy 21 (Down syndrome) was found to have a normal karyotype in blood lymphocytes and fibroblasts. Assessment of the chromosome 21 markers SOD1, CBS, ETS2, D21S11, and BCEI showed partial trisomy by duplication of a chromosome segment carrying the SOD1, CBS, and ETS2 loci and flanked by the BCEI and D21S11 loci, which are not duplicated. This submicroscopic duplication at the interface of 21q21 and 21q22.1 reduces to about 2000-3000 kb the critical segment the trisomy of which is responsible for the phenotype of trisomy 21.

Down syndrome with duplication of a region of chromosome 21 containing the CuZn superoxide dismutase gene without detectable karyotypic abnormality

We report the case of an 18-month-old boy with many typical Down syndrome features but a normal cytogenetic analysis. High-resolution banding techniques on lymphocytes and fibroblasts of the propositus and his parents did not show any detectable abnormality including that of trisomy 21 mosaicism. However, CuZn superoxide dismutase (CuZn SOD) in the patient's red cells was increased as in trisomy 21. DNA analysis (Southern blots) using a human CuZn SOD probe showed that the genotype of the propositus contained three CuZn SOD genes. In situ hybridization on metaphase chromosomes with the same probe confirmed the gene location in a segment enclosing the distal part of 21q21 and 21q22.1. There was no significant labeling on other chromosomes of the patient. These results indicate that the Down syndrome phenotype of this patient is due to microduplication of a chromosome 21 fragment containing the CuZn SOD gene.

Aspects of the structure, function, and applications of superoxide dismutase

The current status of superoxide dismutase (SOD) is that it is an enzyme with diverse ramifications. This review attempts an understanding of SOD as a structural, functional, and biological entity. Accordingly, the review is in three parts. The first part discusses SOD in terms of protein structure, proceeding from primary to secondary and three-dimensional structure for the three forms of SOD: copper/zinc SOD, manganese SOD, and iron SOD. This is the order of structural knowledge of the enzyme. Iron SOD is an enzyme of prokaryotes and some higher plants. Manganese SOD is an enzyme of prokaryotes and eukaryotes. Copper/zinc SOD is an enzyme of eukaryotes and certain prokaryotes. The evolutionary relationships of the three forms of SOD, the status of the copper/zinc SOD gene in prokaryotes, and the cloning and sequencing of SOD genes are discussed. The second part of the review deals with the catalytic mechanism of SOD in the three forms of the enzyme. Structural and mechanistic conclusions from various spectroscopic studies are critically considered. A detailed picture is given of the active site of copper/zinc SOD. The third part is a review of SOD in the general context of oxygen toxicity. After consideration of the question of superoxide toxicity and superoxide pathology, several areas in which SOD has been investigated or used as a tool in a biochemical, pharmacological, or clinical context are discussed, including population genetics; trisomy 21; development and senescence; the nutritional copper, zinc, and manganese status; hemolysis and anemia; oxygen toxicity in the lung and nervous system; inflammation, autoimmune disease and chromosome breakage, ischemia and degenerative changes; radiation damage; and malignancy. A comprehensive picture is given of measurements of SOD activity in disease states, and the question of superoxide-related disease is considered at several points.

Monosomy 21: a new case confirmed by in situ hybridization

A new case of total monosomy 21 in a newborn is described. The diagnosis was first made using the cytogenetic data; it was then confirmed by the dosage of copper-superoxide dismutase (SOD-1) which showed a 50% decrease. In situ hybridization with a probe previously assigned to chromosome 21 was used to rule out the possibility of a partial monosomy with an unbalanced reciprocal translocation.

Ring chromosome 21 and SOD activity of blood cells

A female infant was found to have an abnormal karyotype with mosaicism: 45,XX,-21/46,XX,r(21) (p11.2 q22.3). She showed a slightly decreased level of superoxide dismutase (SOD) activity in erythrocytes, polymorphonuclear and mononuclear leukocytes. The cuprozinc SOD (SOD-1) activity of leukocytes was 70-80% of normal level, while their manganese SOD (SOD-2) activity was within the normal range. The relationship between the chromosomal aberration and the SOD activity is discussed in relation to the gene dosage effect.

The neurobiologic consequences of Down syndrome

Trisomy of the whole or distal part of human chromosome 21 (HSA 21) (Ts21) results in Down Syndrome (DS), which is characterized in part by mental retardation and associated neurological abnormalities. Structural abnormalities observed frequently include reduced brain weight, decreased number and depth of sulci in the cerebral cortices, neuronal heterotopias, and reduced numbers of specific populations of neurons, such as granule cells, in the cerebral cortices. Abnormalities in the structure of cells, primarily of the dendrites, are observed in portions of the neuraxis, such as the hippocampus, cerebellum, and cerebral cortices. Functional abnormalities in membrane properties in peripheral structures and in neurotransmitter enzyme systems in both peripheral and central structures are observed also. Brains of DS individuals over the age of 40 exhibit the characteristic neuropathologic and neurochemical stigmata of Alzheimer's disease (AD). The cholinergic and noradrenergic systems appear to be particularly vulnerable. To elucidate the mechanisms responsible for these abnormalities, identification of the genes located in the distal part of HSA 21 and the systematic study of animal model systems with close genetic homology are essential.

Selenium in plasma and erythrocytes in patients with Down's syndrome and healthy controls. Variation in relation to age, sex and glutathione peroxidase activity in erythrocytes

The mean plasma selenium concentration (P-Se) in 65 patients with Down's syndrome (DS) did not differ from that in 90 healthy controls. The concentration of selenium in the erythrocytes (E-Se) was higher in DS patients than in controls (p less than 0.001). P-Se and E-Se increased progressively with age through childhood in both DS children and controls. The former children, however, started out with higher levels of E-Se and reached adult concentrations earlier (at 7-17 years) than controls (greater than or equal to 18 years). Adult DS patients and controls did not differ in their mean P-Se or E-Se concentration. There was a significant correlation between P-Se and E-Se both in DS patients and in controls. In DS patients each of these two variables was significantly correlated to glutathione peroxidase (GSH-Px) activity in erythrocytes. A sex difference in the DS children, but not in the controls, was observed with regard to P-Se and E-Se levels, these being higher in DS girls during childhood (0-17 years). This was in accordance with an earlier finding of higher GSH-Px activity in DS girls than in DS boys.

Normal superoxide dismutase-1 (SOD-1) activity with deletion of chromosome band 21q21 supports localization of SOD-1 locus to 21q22

The gene for superoxide dismutase-1 (SOD-1) is clearly on chromosome 21, although there is disagreement on the precise band location of SOD-1 on the long (q) arm of number 21. We report a patient with normal superoxide dismutase-1 (SOD-1) activity and an interstitial deletion of chromosome 21 resulting in monosomy for band q21. His phenotype is characterized by moderate mental retardation, a long narrow face, high and arched palate, cardiac murmur, undescended testes, and long hyperflexible extremities. The normal SOD-1 activity supports localization of this enzyme to 21q22.1.

A case of 21q-syndrome with half normal SOD-1 activity

A male Japanese infant was found to have a chromosomal aberration of del(21)(qter leads to q22.1-2) and decreased superoxide dismutase (SOD) activity in erythrocytes and polymorphonuclear and mononuclear leukocytes. The cuprozinc enzyme (SOD-1) level was 40-50% of normal, while the cyanide-insensitive manganese enzyme (SOD-2) activity was within the normal range. Determination of SOD activity in blood cells is a valuable method of classification of the syndrome.

Assignment of the murine interferon sensitivity and cytoplasmic superoxide dismutase genes to chromosome 16

Both hybrids of mouse and human microcells and whole cell hybrids generated by the fusion of primary mouse cells and SV40-transformed human fibroblasts were used to establish the syntenic association of the murine cytoplasmic superoxide dismutase and the interferon sensitivity genes on mouse chromosome 16. This assignment adds two new markers to chromosome 16 and provides another example of an evolutionarily conserved linkage. This finding also provides an animal model both for cellular responsiveness to interferon and for Down's syndrome.