Sequential regulatory loops as key gatekeepers for neuronal reprogramming in human cells.
Direct conversion of somatic cells into neurons holds great promise for regenerative medicine. However, neuronal conversion is relatively inefficient in human cells compared to mouse cells. It has been unclear what might be the key barriers to reprogramming in human cells. We recently elucidated an RNA program mediated by the polypyrimidine tract binding protein PTB to convert mouse embryonic fibroblasts (MEFs) into functional neurons. In human adult fibroblasts (HAFs), however, we unexpectedly found that invoking the documented PTB-REST-miR-124 loop generates only immature neurons. We now report that the functionality requires sequential inactivation of PTB and the PTB paralog nPTB in HAFs. Inactivation of nPTB triggers another self-enforcing loop essential for neuronal maturation, which comprises nPTB, the transcription factor BRN2, and miR-9. These findings suggest that two separate gatekeepers control neuronal conversion and maturation and consecutively overcoming these gatekeepers enables deterministic reprogramming of HAFs into functional neurons.
Key Laboratory of RNA Biology, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China.|Department of Cellular and Molecular Medicine, University of California, San Diego, La Jolla, California, USA.
Yuanchao
Y
Xue
Department of Cellular and Molecular Medicine, University of California, San Diego, La Jolla, California, USA.
Hao
H
Qian
Department of Cellular and Molecular Medicine, University of California, San Diego, La Jolla, California, USA.
Jing
J
Hu
Department of Cellular and Molecular Medicine, University of California, San Diego, La Jolla, California, USA.
Bing
B
Zhou
Department of Cellular and Molecular Medicine, University of California, San Diego, La Jolla, California, USA.
Yu
Y
Zhou
Key Laboratory of RNA Biology, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China.
Xihao
X
Hu
Child Health Institutes of New Jersey, Rutgers-Robert Wood Johnson Medical School, New Brunswick, New Jersey, USA.
Aziz
A
Karakhanyan
Child Health Institutes of New Jersey, Rutgers-Robert Wood Johnson Medical School, New Brunswick, New Jersey, USA.
Zhiping
0000-0002-6183-1233
Z
Pang
Department of Cellular and Molecular Medicine, University of California, San Diego, La Jolla, California, USA.
Xiang-Dong
XD
Fu
D017398:Alternative Splicing / Q000235:genetics; D002460:Cell Line; D065150:Cellular Reprogramming / Q000502:physiology*; D005347:Fibroblasts / Q000166:cytology*; D006801:Humans; D009419:Nerve Tissue Proteins / Q000235:genetics / Q000378:metabolism*; D058953:Neural Stem Cells / Q000378:metabolism*; D009474:Neurons / Q000378:metabolism*; D038941:Polypyrimidine Tract-Binding Protein / Q000235:genetics*
D009419:Nerve Tissue Proteins; D038941:Polypyrimidine Tract-Binding Protein