Manipulating the Mitochondrial Genome To Enhance Cattle Embryo Development

Area of Science:

• Reproductive Biology
• Genetics
• Developmental Biology

Background:

• Mitochondrial DNA (mtDNA) mixing in somatic cell nuclear transfer (SCNT) embryos compromises genetic integrity and hinders development.
• Natural conception involves offspring inheriting mtDNA solely from the oocyte, a state not typically achieved in SCNT.

Purpose of the Study:

• To generate SCNT embryos exclusively containing recipient oocyte mtDNA, mimicking natural conception.
• To assess the developmental potential of SCNT embryos with depleted donor cell mtDNA.
• To investigate the impact of the reprogramming agent Trichostatin A (TSA) on SCNT embryo development.

Main Methods:

• Production of SCNT blastocysts using mtDNA-depleted Holstein fibroblasts and Angus oocytes.
• Comparison of embryo development between mtDNA-depleted and non-depleted donor cells, with and without TSA treatment.
• RNA-sequencing (RNA-seq) analysis to identify differentially expressed genes.

Main Results:

• SCNT embryos produced from mtDNA-depleted cells, when treated with TSA, developed to the blastocyst stage.
• RNA-seq revealed 35 differentially expressed genes between SCNT embryos with and without donor cell mtDNA, with the latter showing improved development.
• TSA treatment positively modulated key developmental genes (CLDN8, TMEM38A, FREM1) in SCNT embryos derived from depleted cells.

Conclusions:

• SCNT embryos produced using mtDNA-depleted donor cells can develop to the blastocyst stage without adverse effects from mixed mtDNA.
• This approach effectively eliminates the presumed damaging consequences of donor and recipient mtDNA coexistence.
• TSA enhances the developmental competence of SCNT embryos with depleted mtDNA, offering a promising strategy for improving SCNT efficiency.