SCNT versus iPSCs: proteins and small molecules in reprogramming.

Somatic cell nuclear transplantation (SCNT) and induced pluripotent stem cell (iPSC) technologies can be employed to change cell fate by reprogramming. The discoveries of SCNT and iPSCs were awarded the Nobel Prize for Physiology and Medicine in 2012, which reaffirmed the importance of cell fate plasticity. However, the low cloning efficiency of SCNT and differences between iPSCs and embryonic stem cells (ESCs) are great barriers and may be caused by incomplete or aberrant reprogramming. Additionally, the well characterized reprogramming factors Oct4, Sox2, Klf4 and c-Myc (OSKM) are not simultaneously expressed at high levels in enucleated or early embryonic oocytes, suggesting reprogramming may be different in the above two methods. Recent studies have demonstrated that small molecules and specific proteins expressed in oocytes and in early embryonic development play important roles in reprogramming by replacing transcription factors, erasing reprogramming memory and accelerating the speed and extent of reprogramming. In this review, we summarize the current state of SCNT and iPSCs technologies and discuss the latest advances in the research of proteins and small molecules affecting SCNT and iPSCs. This is an area of research in which chemical biology and proteomics are combining to facilitate improving cellular reprogramming and production of clinical grade iPSCs.