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Aberrant expression of MICO1 and MICO1OS in deceased somatic cell nuclear transfer calves
Guan-Nan Wang1, Wen-Zhi Yang1, Da Xu1
1Department of Biochemistry and Molecular Biology, College of Life Science, Hebei Agriculture University, Baoding, China.
Abstract:
Incomplete reprogramming of a donor nucleus following somatic cell nuclear transfer (SCNT) results in aberrant expression of developmentally important genes, and is the primary source of the phenotypic abnormalities observed in cloned animals. Expression of non-coding RNAs in the murine Dlk1-Dio3 imprinted domain was previously shown to correlate with the pluripotency of mouse induced pluripotent stem cells. In this study, we examined the transcription of the bovine orthologs from this locus, MICO1 (Maternal intergenic circadian oscillating 1) and MICO1OS (MICO1 opposite strand), in tissues from artificially inseminated and SCNT calves that died during the perinatal period. A single-nucleotide polymorphism (SNP), a T-to-C transition, was used to analyze the allelic transcription of MICO1. Our results indicate monoallelic expression of the MICO1C allele among the six analyzed tissues (heart, liver, spleen, lung, kidney, and brain) of artificially inseminated calves, indicating that this gene locus may be imprinted in bovine. Conversely, we observed variable allelic transcription of MICO1 in SCNT calves. We asked if DNA methylation regulated the monoallelic expression of MICO1 and MICO1OS by evaluating the methylation levels of six regions within or around this locus in tissues with normal or aberrant MICO1 transcription; all of the samples from either artificially inseminated or SCNT calves exhibited hypermethylation, implying that DNA methylation may not be involved in regulating its monoallelic expression. Furthermore, three imprinted genes (GTL2, MEG9, and DIO3) nearby MICO1 showed monoallelic expression in SCNT calves with aberrant MICO1 transcription, indicating that not all of the genes in the bovine DLK1-DIO3 domain are mis-regulated.
Insights
Somatic cell nuclear transfer (SCNT) in cattle leads to abnormal gene expression. This study found variable MICO1 gene transcription in SCNT calves, suggesting potential imprinting defects and developmental issues in cloned animals.
Area of Science:
- Genetics
- Epigenetics
- Developmental Biology
Background:
- Somatic cell nuclear transfer (SCNT) in animals can cause abnormal gene expression due to incomplete nuclear reprogramming.
- The Dlk1-Dio3 imprinted domain is crucial for pluripotency, with its non-coding RNAs linked to stem cell development.
- Understanding gene imprinting in cattle is vital for improving SCNT efficiency and cloned animal health.
Purpose of the Study:
- To investigate the allelic transcription of bovine MICO1 and MICO1OS genes in tissues from normal and SCNT-derived calves.
- To determine if DNA methylation regulates the monoallelic expression of MICO1 and MICO1OS in bovine.
- To assess the broader impact of SCNT on the Dlk1-Dio3 imprinted domain in cattle.
Main Methods:
- Analysis of MICO1 allelic transcription using a single-nucleotide polymorphism (SNP) in tissues from artificially inseminated and SCNT calves.
- Evaluation of DNA methylation levels at six regions within the MICO1/MICO1OS locus.
- Examination of the imprinted status of nearby genes (GTL2, MEG9, DIO3) in SCNT calves.
Main Results:
- Monoallelic expression of the MICO1C allele was observed in all analyzed tissues of artificially inseminated calves, suggesting bovine imprinting.
- Variable allelic transcription of MICO1 was detected in SCNT calves.
- Hypermethylation was present in all samples, indicating DNA methylation is unlikely to regulate MICO1/MICO1OS monoallelic expression.
- Nearby imprinted genes (GTL2, MEG9, DIO3) showed monoallelic expression in SCNT calves with aberrant MICO1 transcription.
Conclusions:
- The MICO1 locus appears to be imprinted in cattle, with potential dysregulation in SCNT.
- DNA methylation does not seem to be the primary mechanism controlling MICO1/MICO1OS imprinting in this context.
- While MICO1 transcription is variable in SCNT calves, not all genes within the bovine DLK1-DIO3 domain exhibit mis-regulation.
