Date of Award


Degree Type


Degree Name

Doctor of Philosophy


Catalases provide cellular protection against the effects of oxygen free radicals. In mice, catalase is coded for by a single gene, Cas-1, located on Chromosome 2, 48 cM from the centromere. A number of genetic strains with variable tissue-specific expression patterns permit the evaluation of molecular mechanisms for the regulation of this housekeeping enzyme.;Transcriptional and post-transcriptional mechanisms of catalase regulation were investigated. The first complete cDNA sequence of Cas-1 is presented and includes 1584 nucleotides encoding 528 amino acids. In addition, 659 bp of 5{dollar}\sp\prime{dollar} genomic upstream region of Cas-1 were sequenced revealing a "CG island", two putative CCAAT boxes, and a GC box. This promoter was examined for patterns of methylation which suggest that the tissue-specific expression of catalase is transcriptionally regulated.;Cas-1 expression was evaluated in mouse tissues of genetic strains and genotypes using enzyme activity assays, polypeptide (western blot) and mRNA analyses. The tissue-specific expression of catalase activity is reflected in the levels of mRNA and suggests transcriptional regulation. The variability in enzyme activity among strains/genotypes is not correlated with mRNA levels, rather it correlates with the level of polypeptide (western blot) suggesting post-transcriptional control. Post-transcriptional regulation is also evident during fetal development and differentiation including birth. The 3{dollar}\sp\prime{dollar} untranslated region (3{dollar}\sp\prime{dollar} UTR) of Cas-1 mRNA reveals several unusual near repeats ((CA){dollar}\sb{lcub}31{rcub},{dollar} (U){dollar}\sb{lcub}15{rcub}{dollar} and (UGUGC){dollar}\sb7\rbrack.{dollar} The mRNA gel shift assay was used to identify proteins which specifically complexed with (CA){dollar}\sb{lcub}31{rcub}{dollar} ({dollar}\sim{dollar}69 kDa) and (U){dollar}\sb{lcub}15{rcub}{dollar} ({dollar}\sim{dollar}38 and 47 kDa) sequences. In addition, the {dollar}\sim{dollar}69 kDa and the {dollar}\sim{dollar}38 kDa proteins are found associated with polysomes. The (U){dollar}\sb{lcub}15{rcub}{dollar}-protein complex may be involved in mRNA stability. Although the function of the (CA){dollar}\sb{lcub}31{rcub}{dollar}-protein complex was not established, it may aid in translational regulation by an undetermined mechanism. One possible model could involve "cross-talk" between the 5{dollar}\sp\prime{dollar} and 3{dollar}\sp\prime{dollar} UTRs of this mRNA via associated proteins. The sequence-specific proteins identified in these experiments may represent the trans-acting factors alluded to in a number of segregation studies on mouse catalases.



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