DIFFERENTIAL DISPLAY OF INTESTINAL MESSENGER-RNAS REGULATED BY DIETARY ZINC

Regulation of gene expression by zinc is well established, especially through the metal response elements of the metallothionein genes; howe ver, most other aspects of the functions of zinc in gene expression re main unknown. We have looked for intestinal mRNAs that are regulated b y dietary zinc status. Using the reverse transcriptase-PCR method of m RNA differential display, we compared intestinal mRNA from rats that w ere maintained for 18 days in one of three dietary groups: zinc-defici ent, zinc-adequate, and pair-fed zinc-adequate. At the end of this per iod, total RNA was prepared from the intestine and analyzed by mRNA di fferential display. Under these conditions, only differentially displa yed cDNA bands that varied in the zinc-deficient group, relative to th e zinc-adequate groups, were selected. Utilizing two anchored oligo-dT 3' PCR primers and a total of 27 arbitrary decamers as 5' PCR primers , our results yielded 47 differentially displayed cDNA bands from inte stinal RNA. Thirty were increased in zinc deficiency, and 17 were decr eased, Nineteen bands were subcloned and sequenced. Eleven of these we re detectable on Northern,blots, of which four were confirmed as regul ated. Three of these have homology to known genes: cholecystokinin, ur oguanylin, and ubiquinone oxidoreductase. The fourth is a novel sequen ce as it has no significant homology in GenBank. The remainder of thos e cloned included novel sequences, as well as matches to reported expr essed sequence tags, and functionally identified genes. Further charac terization of the regulated sequences identified here will show whethe r they are primary or secondary effects of zinc deficiency.