A 178-kb BAC transgene imprints the mouse Gtl2 gene and localizes tissue-specific regulatory elements.
The regulation of genomic imprinting, the allele-specific expression of an autosomal gene, is complex and poorly understood. Imprinted genes are organized in clusters, where cis-acting regulatory elements are believed to interact to control multiple genes. We have used BAC transgenesis in the mouse to begin to delineate the region of DNA required for proper expression and imprinting of the mouse Delta-like1 (Dlk1) and Gene-trap locus2 (Gtl2) imprinted genes. We demonstrate that the Gtl2 gene is expressed from a BAC transgene in mouse embryo and placenta only upon maternal inheritance, as is the endogenous Gtl2 gene. Gtl2 is therefore properly imprinted on the BAC in an ectopic chromosomal location and must carry with it all necessary imprinting regulatory elements. Furthermore, we show that the BAC Gtl2 gene is expressed at levels approaching those of the endogenous gene only in the brain of adult animals, not in other sites of endogenous expression such as the pituitary, adrenal, and skeletal muscle. These data localize the enhancer(s) for brain Gtl2 expression, but not those for other tissues, to the DNA contained within the BAC clone. As the Dlk1 gene is not expressed from the BAC in any tissues, it must require additional elements that are different from those necessary for Gtl2 expression. Our data refine the interval for future investigation of Gtl2 imprinting and provide evidence for distinct regulation of the linked Dlk1 and Gtl2 genes.
Yevtodiyenko
Aleksey
A
Department of Biological Sciences, University of Illinois at Chicago, 900 S. Ashland Avenue, MBRB 4202, Chicago, IL 60607, USA.
Steshina
Ekaterina Y
EY
Farner
Scott C
SC
Levorse
John M
JM
Schmidt
Jennifer V
JV
D000818:Animals; D022202:Chromosomes, Artificial, Bacterial / Q000235:genetics*; D018392:Genomic Imprinting / Q000235:genetics*; D047908:Intracellular Signaling Peptides and Proteins; D008565:Membrane Proteins / Q000235:genetics; D051379:Mice; D008822:Mice, Transgenic; D009928:Organ Specificity; D011506:Proteins / Q000235:genetics*; D012313:RNA / Q000378:metabolism; D062085:RNA, Long Noncoding; D012045:Regulatory Sequences, Nucleic Acid / Q000235:genetics*; D019076:Transgenes / Q000235:genetics*
D047908:Intracellular Signaling Peptides and Proteins; C422882:MEG3 non-coding RNA, mouse; D008565:Membrane Proteins; D011506:Proteins; D062085:RNA, Long Noncoding; C064045:delta protein; D012313:RNA