Somatic cell-like features of cloned mouse embryos prepared with cultured myoblast nuclei.
Cloning by somatic cell nuclear transfer requires silencing of the donor cell gene expression program and the initiation of the embryonic gene expression program (nuclear reprogramming). Failure to silence the donor cell program could lead to altered embryonic phenotypes. Cloned mouse embryos produced using myoblast nuclei fail to thrive in standard embryo culture media but flourish in somatic cell culture media favored by the donor myoblasts themselves, forming blastocysts at a significant rate, with robust morphologies, high total cell number, and a normal allocation of cells to the inner cell mass in most embryos. Myoblast cloned embryos continue expressing the GLUT4 glucose transporter, which is typically expressed in muscle but not in preimplantation stage embryos. Myoblast clones also exhibit precocious enrichment of GLUT1 at the cell surface. Both myoblast and cumulus cell cloned embryos exhibit enhanced rates of glucose uptake. These observations indicate that silencing of the donor cell genome during cloning either is incomplete or occurs progressively over the course of preimplantation development. As a result, cloned embryos initially exhibit many somatic cell-like characteristics. Tetraploid constructs, which possess a transplanted somatic cell genome plus the oocyte-derived chromosomes, exhibit a more embryonic-like pattern of gene expression and culture preference. We conclude that preimplantation stage cloned embryos have profoundly altered characteristics that are donor cell type specific and that exposure of cloned embryos to standard embryo culture conditions may lead to disruptions in basic homeostasis and inhibition of a range of essential processes including further nuclear reprogramming, contributing to cloned embryo demise.
Gao
Shaorong
S
The Fels Institute for Cancer Research and Molecular Biology, Temple University School of Medicine, Philadelphia, Pennsylvania 19140, USA.
Chung
Young Gie
YG
Williams
Jean W
JW
Riley
Joan
J
Moley
Kelle
K
Latham
Keith E
KE
D000818:Animals; D001755:Blastocyst / Q000166:cytology / Q000378:metabolism; D019976:Cloning, Organism / Q000379:methods*; D003470:Culture Media; D015870:Gene Expression; D020868:Gene Silencing; D005947:Glucose / Q000378:metabolism; D051272:Glucose Transporter Type 1; D051275:Glucose Transporter Type 4; D066298:In Vitro Techniques; D051379:Mice; D009004:Monosaccharide Transport Proteins / Q000235:genetics; D009124:Muscle Proteins; D032446:Myoblasts / Q000166:cytology* / Q000378:metabolism; D053652:Nuclear Transfer Techniques; D010641:Phenotype
D003470:Culture Media; D051272:Glucose Transporter Type 1; D051275:Glucose Transporter Type 4; D009004:Monosaccharide Transport Proteins; D009124:Muscle Proteins; C495678:Slc2a1 protein, mouse; C495693:Slc2a4 protein, mouse; D005947:Glucose