Expression of X-linked Genes in Deceased Neonates and Surviving Cloned Female Piglets

摘要

Animal cloning through somatic cell nuclear transfer is very inefficient, probably due to insufficient reprogramming of the donor nuclei, which in turn would cause the dysregulation of gene expression. X-Chromosome inactivation (XCI) is a multi-step epigenetic process utilized by mammals to achieve dosage compensation in females. Our aim was to determine if any dysregulation of X-linked genes, which would be indicative of unfaithful reprogramming of donor nuclei, was present in cloned pigs. Real time reverse transcription polymerase chain reaction (RT-PCR) was performed to quantify the transcript levels of five X-linked genes, XIST, TSIX, HPRT1, G6PD, ARAF1 and one autosomal gene, COL4A1 in major organs of neonatal deceased and surviving female cloned pigs and age-matched control pigs from conventional breeding. Aberrant expression level of these genes was prevalent in the neonatal deceased clones, while it was only moderate in cloned pigs that survived after birth. These results suggest a correlation between the viability of the clones and the normality of their gene expression and provide a possible explanation for the death of a large portion of cloned animals around birth.