Research Advances on Ribosomal Gene Transcription and Somatic Cell Reprogramming
PANG Nan, LIAO Chen, HUANG Xingwei, JIANG Qi, WANG Nan, GAO Meng, LEI Lei*
The rDNA (ribosomal DNA) is a tandem repeat involved in cellular ribosome biosynthesis and located in the nucleolus of the nucleus. The transcription of rDNA mediated by RNA Pol I (polymerase I) is a key step in ribosome biosynthesis, directly affecting cell growth and proliferation. Multiple signaling pathways in mammalian cells affect the transcription of rRNA by regulating Pol I, such as the mTOR, MAPK and PI3K pathways. Somatic cell reprogramming refers to the reversion of differentiated somatic cells to a totipotent state or a pluripotent state under specific conditions. At present, SCNT (somatic cell nuclear transfer) and iPSCs (induced pluripotential stem cells) are two widely studied reprogramming methods. Successfully reprogramming the somatic genome to pluripotency requires both the continuous silencing of somatic-specific genes and the activation of the necessary pluripotency genes. Compared with normal fertilized embryos, SCNT embryos have a problem of low development rate. In SCNT embryos, functional nucleoli development delay and rDNA methylation erasure are incomplete, which may be an important reason for its low development rate. This review summarizes the research progress that affects the regulation of rDNA transcription by the Pol I pathway, analyzes the role of rDNA transcriptional activity in early embryonic development and somatic cell reprogramming, and prospects for possible ways to promote somatic cell reprogramming by regulating rDNA transcription.
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