Inheritance and expression of tissue-specific catalase activity during development and aging in mice

The catalase activity in the liver, kidney, lung, and blood hemolysate was measured in newborn, 21-, 70-, 175-, and greater than 400-day-old mice from the strains BALB/c, Csb, C3H/HeSnJ, C3H/S, C57BL/6J, SW, and 129/ReJ. Catalase activity was found to be highest in the liver (approximately 0.33 U/mg protein) followed by the kidney (approximately 0.13 U/mg protein), lung (approximately 0.05 U/mg protein), and blood hemolysate (approximately 0.03 U/mg protein). ANOVA analysis indicated significant differences in enzyme activity among strains and age groups studied. The developmental profiles of enzyme activity were tissue and strain specific. Catalase activity in the blood, for example, was generally higher at birth and at old age, whereas the kidney catalase activity was low at birth and increased substantially with age. Strains could be classified as normal (129/ReJ, BALB/c, C3H/HeSnJ, C3H/S), hypocatalasemic (C57BL/6J, SW), and acatalasemic (Csb) with respect to enzyme activity and it was on this basis that the inheritance of the catalase phenotype was studied using appropriate crosses. The enzyme activity level in each tissue appears to be governed by a unique set of genetic regulators/modifiers that interact with a single structural gene (Cs) or its product to produce the catalase phenotype. Some of these (e.g., Ce-1 and Ce-2) have been previously described but based on the results of various crosses reported here, more must exist that remain still uncharacterized at the molecular level. Models proposed for the inheritance of the catalase phenotype vary in complexity from single allelic differences between strains (e.g., BALB/c x Csb; blood) to a system of multiple interacting genetic determinants (e.g., BALB/c x Csb; liver) each having dominant (e.g., C57BL/6J over BALB/c; liver) and recessive components (e.g., gene(s) conferring the acatalasemic phenotype in BALB/c x Csb; blood and kidney). Such results are important and offer an interesting model to further characterize aspects of eukaryotic gene regulation.     

Molecular analysis of an acatalasemic mouse mutant

The Csb acatalasemia mouse mutant differentially expresses reduced levels of catalase activity in a tissue specific manner. In order to pinpoint the molecular lesion that imparts the acatalasemia phenotype in Csb mice we have utilized the polymerase chain reaction technique to isolate catalase cDNA clones from control and Csb mouse strains. Sequence analyses of these cDNA clones have revealed a single nucleotide difference within the coding region of catalase between control and Csb mice. This nucleotide transversion (G----T) is located in the third position of amino acid 11 in the catalase monomer. In control mouse strains glutamine (CAG) is encoded at amino acid 11, while in Csb mice this codon (CAT) encodes histidine. This amino acid is located within a region that forms the first major alpha-helix in the amino-terminal arm of the catalase subunit and, as such, may render the catalase molecule unstable under certain physiological conditions.     

An abundant androgen-regulated mRNA in the mouse kidney.

We have identified an abundant 20,000 dalton protein (KAP) by in vitro translation of male mouse kidney mRNA. This protein is synthesized in reduced amounts from female kidney mRNA. A KAP cDNA fragment was purified and used for nucleic acid hybridization studies. Females and castrated males have 10 and 200 fold lower levels, respectively, of KAP mRNA relative to males. The administration of testosterone to females or castrated males results in the induction of KAP mRNA to normal male levels. Testicular feminized (Tfm) mice have 3 fold lower levels of KAP mRNA relative to normal males and are not induced by testosterone. KAP mRNA is not found in significant amounts in tissues other than the kidney, and the KAP gene renatures with kinetics similar to single-copy DNA. With the rapidly expanding knowledge of mouse genetics, KAP should prove useful in determining genetic factors which regulate the inducibility and tissue specificity of a hormonally regulated gene.     

Tissue and organ expression of catalase in acatalasemic beagle dogs.

Acatalasemic Beagle dogs which were maintained in our laboratories showed no sign of catalase activity at all in the erythrocytes, and glutathione peroxidase and superoxide dismutase were at normal levels. Immunoblotting analysis demonstrated that no catalase protein is detectable in their erythrocytes. On the other hand, catalase activity was detected in other tissues and organs, albeit at varying, lower levels than in normal dogs. Quantitative immunoblotting analysis consistently demonstrated that the catalase protein is expressed in the liver and kidneys of acatalasemic dogs in proportion to the activity in these organs. The catalase mRNA expressions in the blood, liver and kidneys in acatalasemic dogs were almost the same as those in normal dogs. These results suggested that catalytically normal catalase protein is translated from mRNA in the tissues and organs including erythrocytes, but in erythrocytes this enzyme protein is disposed of by an unknown mechanism.     

Murine glutamine synthetase: Cloning, developmental regulation, and glucocorticoid inducibility

We have cloned the murine glutamine synthetase (GS) gene and measured GS enzyme activity and mRNA in five tissues (retina, brain, liver, kidney, and skeletal muscle) during perinatal development. Retinal GS enzyme activity increases 200-fold between Day 1 and Day 21 and is accompanied by an increase in the level of GS mRNA; developmental regulation in other tissues is much less dramatic. Based on Southern blotting analysis, a single GS gene gives rise to the tissue-specific patterns of GS mRNA expression. The increase in murine retinal GS observed during perinatal development is similar in magnitude to that observed in the chicken retina just prior to hatching. In the embryonic chicken retina, glucocorticoid hormones mediate a large increase in the level of GS mRNA. However, although glucocorticoids induce a 12-fold increase in GS mRNA in murine skeletal muscle, expression of the retinal enzyme and mRNA is only modestly glucocorticoid-inducible in the mouse. Therefore, despite the hormonal responsiveness of the murine GS gene, it is not likely that glucocorticoids are important physiological modulators of the developmental rise in murine retinal GS.