Genetically imprinted genes are only expressed from either the maternal or paternal allele. This is due to differential """"""""marks"""""""" established on the DNA of sperm and oocytes during gametogenesis, which are maintained throughout embryogenesis and subsequent development. In somatic cloning by nuclear transfer, however, no separate gametes with differentially marked genes are involved, both sets of chromosomes are derived from the same donor cell. Therefore, it is of interest to find out how the expression of imprinted genes is regulated in somatic clones. This question is intriguing because signs of imprinting disruption have been observed in cloned cattle regardless of donor cell type or donor age. Developmental defects such as high fetal and neonatal deaths and large calves are reminiscent of experimentally created imprinting disruptions (biallelic expression of imprinted genes) in mice and naturally occurring imprinting diseases in humans. Therefore, we hypothesize that some of the defects consistently observed in somatic clones are likely associated with aberrant expressions of imprinted genes after cloning. Our long-term objective is to understand whether and how imprinted genes are altered in clones.
Our specific aims of this proposal are 1) to determine whether imprinting patterns are disrupted in cloned animals derived from adult somatic cells, and 2) to determine if the levels of mRNA for imprinted genes are altered in somatic clones.
These specific aims are capitalized on our preliminary results that 1) we have collected samples from eleven live or dead somatic cattle clones which showed signs of imprinting disruptions, and 2) we have established polymorphic assays for IGF2 and IGF2R in bovine and our donor is heterozygous in both loci. Finding fromthese explorative studies will not only provide insights into the low efficiency of somatic cloning but also significantly further our understanding of the establishment and regulation of genetic imprinting during mammalian development.

Agency
National Institute of Health (NIH)
Institute
Eunice Kennedy Shriver National Institute of Child Health & Human Development (NICHD)
Type
Small Research Grants (R03)
Project #
5R03HD040889-02
Application #
6526456
Study Section
Pediatrics Subcommittee (CHHD)
Program Officer
Tasca, Richard J
Project Start
2001-08-01
Project End
2003-07-31
Budget Start
2002-08-01
Budget End
2003-07-31
Support Year
2
Fiscal Year
2002
Total Cost
$71,500
Indirect Cost
Name
University of Connecticut
Department
Veterinary Sciences
Type
Schools of Earth Sciences/Natur
DUNS #
City
Storrs-Mansfield
State
CT
Country
United States
Zip Code
06269
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Curchoe, Carol Lynn; Zhang, Shouquan; Yang, Lan et al. (2009) Hypomethylation trends in the intergenic region of the imprinted IGF2 and H19 genes in cloned cattle. Anim Reprod Sci 116:213-25
Suteevun-Phermthai, T; Curchoe, C L; Evans, A C et al. (2009) Allelic switching of the imprinted IGF2R gene in cloned bovine fetuses and calves. Anim Reprod Sci 116:19-27
Li, Chao; Bin, Yanfang; Curchoe, Carol et al. (2008) Genetic imprinting of H19 and IGF2 in domestic pigs (Sus scrofa). Anim Biotechnol 19:22-7
Curchoe, Carol; Zhang, Shouquan; Bin, Yanfang et al. (2005) Promoter-specific expression of the imprinted IGF2 gene in cattle (Bos taurus). Biol Reprod 73:1275-81
Zhang, Shouquan; Kubota, Chikara; Yang, Lan et al. (2004) Genomic imprinting of H19 in naturally reproduced and cloned cattle. Biol Reprod 71:1540-4