image: Image: The human genome is a complex place, composed of vast amounts of repetitive, retroviral and transposable elements (TEs). Originally thought to be only parasitic DNA elements, TEs substantially outnumber coding sequence genes and take up nearly half of the human genome. Critically, TEs have been attributed a wide range of biological functions, ranging from the direct co-option of viral genes in trophoblast development and the immune system, to evolutionary innovations in transcription factor binding to DNA. TEs are released from repression during early embryogenesis, as the genome is demethylated and reprogrammed, and intriguingly, TEs are similarly released from repression when somatic cells are in vitro reprogrammed to induced pluripotent stem cells. TEs also have intimate links to epigenetic regulation, as TEs are regulated by the epigenetic system, and are simultaneously regulating the epigenetic system. Indeed, it often seems that TEs sit at the center of the crossroads between embryogenesis, embryonic stem cells, reprogramming, and long noncoding RNAs. TEs are fascinating molecules, which sometimes seem to be both parasitic and symbiotic at the same time, and they will likely have many fascinating, as yet undiscovered, important biological roles (see the review by Andrew Paul Hutchins and Duanqing Pei on page 1722-2015 No.20 issue of Science Bulletin). view more
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Stem cells sustain the capacity of self-renewal and differentiation into specialized cells, offering exciting promises in both basic and applied research. As an example of an applied purpose, stem cells can be used as a resource in regenerative medicine for generation of appropriate cell types in cell replacement therapy, which has been becoming a new pillar of human therapeutics. While it has been displaying obvious advantages over other therapeutic strategies, the successful use of cell-based therapeutics is still facing the following major challenges: (1) how to efficiently derive stem cells, including pluripotent stem cells and adult stem cells; (2) how to stably maintain stem cells in vitro; (3) how to largely obtain functional cells through in vitro differentiation of stem cells; and (4) how to safely transplant donor cells into patients. Actually, what makes application of stem cells rapidly move forward into clinic depends on how much the efforts have been making on basic study of stem cells. Therefore, Science Bulletin invited Professor Jinsong Li, the promising young principal investigator on stem cell research in Institute of Biochemistry and Cell Biology, SIBS, CAS to organize this special topic on "stem cell, basis and application".
In this special topic, 5 high-quality and peer-reviewed articles were presented. Among them, 4 are reviews and one is original research paper, covering diverse aspects and topics on stem cells such as cell source for generation of induced pluripotent stem (iPS), epigenetic roles in somatic reprogramming and embryonic development, and cell source for treating disease. Cell source of iPS cells will be critical for their application in patient-specific therapy. IPS cells could be efficiently generated by Yamanaka factors from a subpopulation of adipose tissue-derived cells that are mainly composed of progenitor cells. However, it is not clear whether terminally differentiated adipocytes could be used as donors for deriving iPS cells. In this special topic, Donghai Wu and colleagues demonstrate that terminally differentiated adipocytes can be reprogrammed into iPS cells using Yamanaka factors plus Rarγ and Lrh1, two nuclear hormone receptors, which have been recently applied to promote the iPS cell generation from mouse and human fibroblasts. Epigenetic regulations are critical for cell fate determinations. One review article by Shaorong Gao and colleagues provides us a comprehensive overview of epigenetic mechanisms involved in somatic cell reprogramming to pluripotency induced by Yamanaka factors.The paper by Duanqing Pei and Andrew Paul Hutchins describe the functions of transposon elements in embryonic development, ESC self-renew and somatic reprogramming. On the other hand, Jianwei Jiao and colleagues presents a state-of-art analysis of epigenetic roles in embryonic neurogenesis.Investigation into the detailed process of cell lineage formation in vivo will not only aid us reveal the mysteries of the embryonic development, but may also yield clues to improve the in vitro differentiation system for more efficient generation of donor cells from stem cells. Finally, Qi Zhou and colleagues discuss the progress of β-cell derivation and transplantation for cell-based therapy in diabetes mellitus.
It is expected this special topic will attract attention and will contribute to the growth of the stem cell biology in years to come.
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special topic on "stem cell, basis and application" :
1. Jinsong Li (2015) Stem cell, basis and application. Sci Bull 60:1711-1712
2. Tao Nie, Wei Deng, Xuefei Gao, Wei Sun, Xiaoyan Hui, Hong Song, Dajiang Qin, Aimin Xu, Peng Li, Pentao Liu, Liangxue Lai, Donghai Wu (2015) Reprogramming mature terminally differentiated adipocytes to induced pluripotent stem cells. Sci Bull 60:1752-1758
3. Rui Gao, Xiaoyu Liu, Shaorong Gao (2015) Progress in understanding epigenetic remodeling during induced pluripotency. Sci Bull 60:1713-1721
4. Andrew Paul Hutchins, Duanqing Pei (2015) Transposable elements at the center of the crossroads between embryogenesis, embryonic stem cells, reprogramming and long non-coding RNAs. Sci Bull 60:1722-1733
5. Tianjin Shen, Fen Ji, Jianwei Jiao (2015) Epigenetics: major regulators of embryonic neurogenesis. Sci Bull 60:1734-1743
6. Ying Wang, Tang Hai, Lei Liu, Zhonghua Liu, Qi Zhou (2015) Cell therapy in diabetes: current progress and future prospects. Sci Bull 60:1744-1751
The special topic is available for free viewing at: http://www.scibull.com:8080/EN/volumn/volumn_6535.shtml
Journal
Science Bulletin