Gene expression and imprinting in mice cloned by nuclear transfer

Most cloned mammals derived by nuclear transfer (NT) die during gestation, and those surviving to birth frequently show increased birth weights, enlarged dysfunctional placentas, and neonatal mortality associated with respiratory distress and metabolic abnormalities. These abnormalities may reflect inadequate reprogramming of the donor nucleus to a state fully compatible with normal development. As inadequate reprogramming should lead to abnormal gene regulation in the clones, we have examined gene expression in clones to determine the extent of dysregulation and whether particular genes are commonly affected in clones. Abnormal imprinted gene expression has been proposed as a likely cause for some phenotypes observed in clones. Imprinted genes frequently affect fetal growth and some phenotypes similar to those seen in cloning are found upon in vitro embryo culturing, a process known to affect the expression of some imprinted genes. Because imprinting is normally established in the gametes and maintained in the early embryo, imprinted genes are likely to be resistant to reprogramming after nuclear transfer. We have examined imprinted gene expression in neonatal cloned mice derived from embryonic stem (ES) cells. In ES cell NT mice and their placentas, we found that many imprinted genes had abnormal gene expression levels. Similar expression abnormalities were observed upon in vitro differentiation of the ES cell donor populations from which the NT mice were derived. Additionally, mice cloned from the same ES cell subclone showed significantly varying imprinted gene expression suggesting that the epigenetic state of the ES cell genome was unstable.

Department dc:contributor.department

Massachusetts Institute of Technology. Dept. of Biology.

Grantor dc:publisher

Massachusetts Institute of Technology

Year dc:date.issued

2002

Author dc:creator

• Humpherys, David G. (David Glenn), 1972-

Advisor dc:contributor.advisor

• Rudolph Jaenisch.

• Biology.

Statement dc:rights

• M.I.T. theses are protected by copyright. They may be viewed from this source for any purpose, but reproduction or distribution in any format is prohibited without written permission. See provided URL for inquiries about permission.

Licence dc:rights.uri

• http://dspace.mit.edu/handle/1721.1/7582

Language dc:language.iso

eng

Handle dc:identifier.uri

http://hdl.handle.net/1721.1/8384

OAI identifier oai:identifier

oai:dspace.mit.edu:1721.1/8384