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Understanding the mechanisms of stem cell proliferation, self-renewal and differentiation is fundamental for stem cell biology. Stem cells proliferate by either symmetric division or asymmetric division. Through asymmetric division, stem cells self-renew and differentiate to mature cells. Stem cells could also divide symmetrically to give rise to differentiated cells. Besides intrinsic cues, proliferation and self-renewal of most stem cell types also rely on extrinsic signals from niche or surrounding cells. Failure in any of these factors may result in disturbed stem cell proliferation, self-renewal or differentiation and/or generate cancer stem cells that drive cancer development.
This special focus aims to expand the understanding of regulations of stem cell self-renewal, differentiation and maintenance. Experts in the field of stem cells have discussed about recent advances on stem cells in mammals and fruit fly Drosophila melanogaster. Various topics on stem cells are brought together, providing us a broader picture of stem cell study.
Dr. Hirth and colleague highlight genetic mechanisms of asymmetric division of Drosophila neural stem cells and growth control of neural stem cell self-renewal and differentiation, providing insights into the relation between asymmetric cell division and growth control of Drosophila neural stem cells. Dr. Sohail and colleagues elaborate mammalian neural stem cell self-renewal, growth and differentiation emphasizing transcription factors functioning in part of major signaling pathways that regulate neural stem cell homeostasis during nervous system development.
A critical pre-requisite for stem cell maintenance and function is the intimate contact between stem cells and the niche, the specific microenvironment that adult stem cells reside in. Dr. Xi reviews mechanism of anchoring stem cells by cell adhesion molecules in both Drosophila germline stem cell niche and tissue-specific mammalian adult stem cell niches.
Relatively recently, micro-RNAs, a family of small, non-protein-coding RNAs, have been shown to be critical for stem cell development. Drs. Hime and Somers sketch recent advances in micro-RNA functions in mammalian stem cells, revealing mutual regulation between micro-RNAs and transcription factors, functions of micro-RNAs in stem cell proliferation and cancer.
This focus will definitely stimulate new discoveries in fundamental issues of stem cells and tumorigenesis and may potentially bring about therapeutic opportunities.
Dr. Hongyan Wang is an Assistant Professor at Duke-NUS Graduate Medical School Singapore, Deptartment of Physiology, School of Medicine, National University of Singapore and NUS Graduate School for Integrative Sciences and Engineering. Dr. Wang received her Ph.D. at Temasek Life Sciences Laboratory, National University of Singapore in 2004 and was a postdoctoral research fellow at the same institute. She was a visiting scholar on a one-year postdoctoral training stint at University of California, San Francisco, after which she joined Duke-NUS Graduate Medical School Singapore as a faculty in 2007. Dr. Wang's work focuses on neural stem cells and tumorigenesis in Drosophila.
Previously published online as a Cell Adhesion & Migration E-publication: www.landesbioscience.com/journals/celladhesion/article/9952