Reprogramming barriers in bovine cells nuclear transfer revealed by single-cell RNA-seq analysis

Area of Science:

• Reproductive biology
• Developmental biology
• Genomics

Background:

• Somatic cell nuclear transfer (SCNT) has advanced, but low live birth rates persist in bovine embryos.
• Single-cell RNA sequencing (scRNA-seq) offers detailed insights into SCNT embryo development.

Purpose of the Study:

• To investigate developmental defects in bovine SCNT embryos using scRNA-seq.
• To compare SCNT embryos with in vitro fertilization (IVF) embryos and assess the impact of different donor cells.

Main Methods:

• Bovine fibroblasts and three-factor induced pluripotent stem cells (3F biPSCs) were used as SCNT donors.
• Single blastomere transcriptomes were analyzed using scRNA-seq.
• Differential gene expression and pseudotime analyses were performed.

Main Results:

• SCNT embryos showed widespread defects in metabolism and epigenetic modification compared to IVF embryos.
• Defective gene activation (e.g., ZSCAN4) and protein network disruptions were observed in SCNT embryos.
• Partially reprogrammed 3F biPSCNT embryos exhibited more dysregulation than SCNT embryos, indicating hindered reprogramming.

Conclusions:

• SCNT in cattle leads to significant developmental abnormalities at the transcriptomic level.
• The use of partially reprogrammed cells as SCNT donors impairs nuclear transfer embryo reprogramming.
• Findings provide insights into SCNT embryo development and potential strategies for improving efficiency.