Metallothionein mRNA expression in mice homozygous for chromosomal deletions around the albino locus.
Deletions in chromosome 7 of the mouse affect the expression of the metallothionein gene Mt-1, which maps on chromosome 8, and steady-state levels of Mt-1 mRNA are reduced to 15-40% of normal in livers of newborn mice homozygous for either the c3H or c14CoS deletion. Glucocorticoids fail to induce hepatic Mt-1 mRNA levels in deletion homozygotes in contrast to normal littermates. However, zinc chloride is effective in inducing Mt-1 mRNA levels in livers of deletion homozygotes as well as of their normal littermates. Other tissues (e.g., kidney and intestine) of deletion homozygotes express basal levels of Mt-1 mRNA higher than those of normal littermates. In the intestine these are furthermore inducible by both hormonal and metal agents. Thus, loss of inducibility of the Mt-1 gene in deletion homozygotes concerns glucocorticoids only and is furthermore restricted to specific cell types (i.e., hepatocytes). The trans-acting factor(s) normally encoded in the deleted region of chromosome 7 appears to be instrumental in conferring on the metallothionein gene in hepatocytes the essential competence to respond to hormonal inducing signals.
Department of Biological Sciences, University of Pittsburgh, PA 15260.
D
D
DeFranco
S M
SM
Morris
C M
CM
Leonard
S
S
Gluecksohn-Waelsch
D000417:Albinism / Q000235:genetics*; D000818:Animals; D002712:Chlorides / Q000494:pharmacology; D002872:Chromosome Deletion; D002874:Chromosome Mapping; D003907:Dexamethasone / Q000494:pharmacology; D005786:Gene Expression Regulation / Q000187:drug effects; D006720:Homozygote; D007413:Intestinal Mucosa / Q000378:metabolism; D007668:Kidney / Q000378:metabolism; D008099:Liver / Q000378:metabolism; D008668:Metallothionein / Q000235:genetics*; D051379:Mice; D008817:Mice, Mutant Strains / Q000235:genetics*; D012333:RNA, Messenger / Q000096:biosynthesis*; D015032:Zinc / Q000494:pharmacology; D017967:Zinc Compounds
D002712:Chlorides; D012333:RNA, Messenger; D017967:Zinc Compounds; D003907:Dexamethasone; C016837:zinc chloride; D008668:Metallothionein; D015032:Zinc