Function of Myc for Generation of Induced Pluripotent Stem Cells
Somatic cells can be reprogrammed into induced pluripotent stem (iPS) cells by the transduction of defined factors. c-Myc is one of the original reprogramming factors, and it increases the number of iPS cells generated in both mouse and human systems when it is added to another three factors (Sox2, Oct3/4, and Klf4). However, exogenously expressed c-Myc, especially by retroviruses, causes tumorigenicity in iPSC-derived chimeric mice during long-term observation. Although iPS cells can be generated in the absence of c-Myc, the quality of iPS cells seems to be low. L-Myc, one of the Myc family genes, can efficiently generate both mouse and human iPS cells. Importantly, tumorigenicity is hardly observed in chimeric mice produced with L-Myc iPS cells. The iPS cells generated with L-Myc are safer, of high quality, and therefore are considered to be useful for future clinical applications.