The 3' untranslated region plays a role in the targeting of metallothionein-I mRNA to the perinuclear cytoplasm and cytoskeletal-bound polysomes.
The mechanism of localisation of metallothionein-I (MT-I) mRNA was studied in transfected cells by in situ hybridisation and cell fractionation. Hepatoma cells were transfected with the 5'-untranslated region and coding region of the beta-globin gene alone or linked to either the beta-globin 3'-untranslated region (3'-UTR) or the MT-I 3'-UTR. The wild-type beta-globin mRNA and the beta-globin mRNA lacking its native 3'-UTR were present in free and cytoskeletal-bound polysomes to a similar extent and showed no localisation. Chimaeric globin-metallothionein transcripts were significantly enriched in cytoskeletal-bound polysomes and were localised in the perinuclear cytoplasm. Chimaeric globin-metallothionein and wild-type globin transcripts were of similar stability. Chinese Hamster Ovary cells were transfected with constructs in which the MT-I 5'-untranslated region and coding sequences were linked to either the endogenous 3'-UTR or the glutathione peroxidase 3'-UTR. Wild-type MT-I transcripts were localised in the perinuclear cytoplasm but the chimaeric MT-I-glutathione peroxidase transcripts showed no distinct localisation. The results indicate that the 3'-UTR of MT-I mRNA contains a localisation signal which promotes both the association of the mRNA with the cytoskeleton and its perinuclear localisation.
Mahon
P
P
Intracellular Targeting Group, Rowett Research Institute, Bucksburn, Aberdeen, UK.
Partridge
K
K
Beattie
J H
JH
Glover
L A
LA
Hesketh
J E
JE
D000818:Animals; D001665:Binding Sites; D016466:CHO Cells; D002467:Cell Nucleus / Q000378:metabolism; D006224:Cricetinae; D003593:Cytoplasm / Q000378:metabolism*; D003599:Cytoskeleton / Q000378:metabolism*; D017930:Genes, Reporter; D005914:Globins / Q000235:genetics; D008668:Metallothionein / Q000235:genetics*; D011132:Polyribosomes / Q000378:metabolism*; D014176:Protein Biosynthesis; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism*; D051381:Rats; D014162:Transfection; D014407:Tumor Cells, Cultured
D012333:RNA, Messenger; D005914:Globins; D008668:Metallothionein