Senescence is accelerated through donor cell specificity in cloned pigs

Area of Science:

• Reproductive biology
• Genetics
• Cellular senescence

Background:

• Somatic cell nuclear transfer (SCNT) cloning can result in offspring abnormalities like large offspring syndrome and early mortality.
• Phenotypic anomalies, including premature aging and wrinkled skin, have been observed in cloned pigs derived from specific donor cell types.

Purpose of the Study:

• To investigate the cause of the wrinkled phenotype in SCNT-cloned pigs.
• To determine if the observed abnormalities are due to senescence, donor cell genetic issues, or epigenetic reprogramming errors.

Main Methods:

• Analysis of senescence biomarkers: telomere length, senescence-associated β-galactosidase (SA-β-gal) activity, and expression of GAPDH and β-actin.
• Assessment of DNA methylation status in repetitive sequences (PRE-1 and centromeric satellite DNA).
• Measurement of mRNA levels for six imprinted genes (Copg2, Mest, Igf2R, GNAS, SNRPN, Ube3a).

Main Results:

• Wrinkled cloned pigs exhibited significantly shorter telomeres compared to normal cloned and non-cloned pigs.
• Increased SA-β-gal activity and repressed GAPDH and β-actin expression were observed in wrinkled cloned pigs.
• Reduced mRNA levels of Mest, GNAS, and Ube3a were detected in wrinkled cloned pigs, indicating donor-specific genetic abnormalities.

Conclusions:

• The wrinkled phenotype in SCNT-cloned pigs is associated with cellular senescence markers and shortened telomeres.
• Gene expression analysis points to genetic abnormalities within the donor cells as the origin of these SCNT-related defects.
• These findings highlight the importance of donor cell quality in SCNT for successful cloning outcomes.