Investigation Of Genomic Imprinting Pattern Of Nnat, Mkrn3and Nap1l5in Rabbits

Genomic imprinting is a unique epigenetic process that genes are monoallelicallyexpressed from one parental allele. It coordinates the mammalian development andgrowth. The previous researches have reported that imprinting disorders may causedevelopmental defects, excessive growth, growth deficiency, abnormal behavior,tumor and so on. It have been demonstrated imprinted genes plays a key role on themechanism of genetic diseases, tumor, and also would provide fundamentalinformation for gene therapy. In addition, it is important to note that genomicimprinting have been become a hot topic in the study of the early development of thefetus and parthenogenesis.As an experimental animal, rabbits have more unique advantages than mice, suchas easy breeding, a quick reproduction cycle and more similar in physiological aspectsto human. Thus, rabbit is a more appropriate experimental animal than mice. So far,imprinted genes in mice, human, pigs and cattle have been well documented. Forrabbit, the data about imprinted genes are very few, only one imprinted gene in rabbithave been reported.In this study, bioinformatics were firstly used to select three candidate imprintedgenes: Nnat, Mkrn3and Nap1l5. The methylation status of three candidate imprintedgenes in sperm and oocytes were determined by bisulfite sequencing PCR andcombined bisulfite restriction analysis. The data showed that Nnat, Mkrn3and Nap1l5were complete demethylation in rabbit sperm, while full methylation in oocytes.These results confirmed that Nnat, Mkrn3and Nap1l5are maternally imprinted genesin rabbits.The expression level of Nnat, Mkrn3and Nap1l5were determined in differenttissues in rabbits by quantitative real-time PCR and RT-PCR. We found that Nnat expressed in adult rabbit brain and eye but not in the liver and kidney, which indicatedthat Nnat may play an important role in neural and eye development in rabbits. Mkrn3also expressed in brain but not in liver, which suggested that Mkrn3may play a role inthe regulation of nerve development. Nap1l5expressed in brain, kidney and eyes, butnot in liver, which means it may be involved in the nerve development.In conclusion, the results above showed that Nnat, Mkrn3and Nap1l5werematernally imprinted genes in rabbit. The expression pattern of the three imprintedgenes was tissues-specific, representing that they were differentially involved indevelopmental regulation of different tissues. In addition, we also found that theexpression pattern of the three imprinted genes is consistent with human and mice.The results in this study provided useful information for the study of developmentalregulation of early embryos and the mechanism of disease in rabbits.