Coexpression analysis identifies nuclear reprogramming barriers of somatic cell nuclear transfer embryos

Area of Science:

• Reproductive biology
• Developmental biology
• Genetics

Background:

• Somatic cell nuclear transfer (SCNT) is a key technology for mammalian asexual reproduction, exemplified by the cloned sheep 'Dolly'.
• Despite SCNT's potential, cloned embryos exhibit poor developmental outcomes, suggesting underlying molecular mechanisms are not fully understood.
• Understanding gene expression dynamics in SCNT embryos is vital for improving nuclear reprogramming efficiency.

Purpose of the Study:

• To establish a comprehensive transcriptome resource for SCNT embryos derived from various donor cells.
• To identify gene expression patterns and regulatory pathways associated with reprogramming barriers in SCNT embryos.
• To compare reprogramming efficiency between inter- and intra-SCNT embryos.

Main Methods:

• Transcriptome sequencing of SCNT embryos from different inter- and intra-donor cell types.
• Gene co-expression network analysis to identify cell-specific modules.
• Enrichment analysis of regulatory pathways involved in reprogramming.

Main Results:

• A valuable transcriptome dataset for SCNT embryos was generated.
• Twenty-six cell-specific gene modules were identified, highlighting pathways linked to reprogramming challenges.
• Inter-SCNT embryos showed incomplete reprogramming compared to intra-SCNT embryos, with failed activation of master genome trigger genes (TFIID, RNA polymerase, mediators) and delayed KDM epigenetic regulators.

Conclusions:

• Inter-SCNT embryos fail to activate essential self-sustained gene expression pathways, relying only on maternal mRNA.
• Incomplete activation of key transcriptional machinery and delayed epigenetic regulation contribute to reprogramming barriers in inter-SCNT embryos.
• This study offers novel insights into the molecular mechanisms governing nuclear reprogramming in SCNT.