Professor Sun Yat-sen University Guangzhou, Guangdong, China (People's Republic)
Abstract: The pluripotency state of embryonic stem cells (ESCs) is determined by both their epigenome and transcriptome. The transcriptional co-activator complex SAGA plays a critical role in a wide range of biological processes. We observed that SAGA complex is stably expressed in various types of high-potency stem cells, including spermatogonial stem cells, haematopoietic stem cells, mesenchymal stem cells, and embryonic stem cells (ESCs). However, whether and how SAGA mediates epigenetic modifications and pluripotent gene transcription is not fully understood. Sgf29, a subunit of the transcriptional co-activator complex SAGA, plays a critical role in a wide range of biological processes. Overexpress Sgf29 in dox-induced Flag tagged Sgf29 mESC line did not affect the morphology, embryoid body (EB) information and the pluripotent markers Oct4 and Nanog expression. Induced knockout of Sgf29 was achieved by inducing Cas9 protein expression in the presence of Sgf29-targeted gRNAs. A significant increase in differentiated ESC colonies was observed after 72 h of iKO. It was found that Sgf29 KO significantly reduced Oct4, Nanog, and Sox2. RNA-seq was used to assess the gene expression profile of WT and Sgf29 KO mESCs. Gene ontology (GO) analysis revealed that the major pathways enriched for down-regulated genes were pattern specification process, embryonic organ morphogenesis, cell fate commitment and cell fate specification. Down-regulated genes included pluripotency-associated factors such as Pou5f1 (Oct4), Nanog. Additionally, Sgf29 KO significantly inhibited EB growth and proliferation. Finally, we found that dis-functional SAGA induced the differentiation of mESCs by reducing H3K9ac and chromatin accessibility at the promoters and enhancers of key pluripotency genes. These results suggest that SAGA plays a critical role in maintaining the pluripotency and differentiation fate of mESCs.
Funding Source: This study was funded by the National Natural Science Foundation of China (82271688), the Guangdong Province Excellent Youth Team Project (2024B1515040009).
