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RISS 인기검색어
- 검색키워드
- 저자 : Arauzo-Bravo, Marcos J. (검색결과 3 건)
- 무료
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A Novel Feeder-Free Culture System for Expansion of Mouse Spermatogonial Stem Cells
Choi, Na Young,Park, Yo Seph,Ryu, Jae-Sung,Lee, Hye Jeong,Arauzo-Bravo, Marcos J.,Ko, Kisung,Han, Dong Wook,Scholer, Hans R.,Ko, Kinarm Korean Society for Molecular and Cellular Biology 2014 Molecules and cells Vol.37 No.6
Spermatogonial stem cells (SSCs, also called germline stem cells) are self-renewing unipotent stem cells that produce differentiating germ cells in the testis. SSCs can be isolated from the testis and cultured in vitro for long-term periods in the presence of feeder cells (often mouse embryonic fibroblasts). However, the maintenance of SSC feeder culture systems is tedious because preparation of feeder cells is needed at each subculture. In this study, we developed a Matrigel-based feeder-free culture system for long-term propagation of SSCs. Although several in vitro SSC culture systems without feeder cells have been previously described, our Matrigel-based feeder-free culture system is time- and cost-effective, and preserves self-renewability of SSCs. In addition, the growth rate of SSCs cultured using our newly developed system is equivalent to that in feeder cultures. We confirmed that the feeder-free cultured SSCs expressed germ cell markers both at the mRNA and protein levels. Furthermore, the functionality of feeder-free cultured SSCs was confirmed by their transplantation into germ cell-depleted mice. These results suggest that our newly developed feeder-free culture system provides a simple approach to maintaining SSCs in vitro and studying the basic biology of SSCs, including determination of their fate.
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Conversion of genomic imprinting by reprogramming and redifferentiation
Kim, Min Jung,Choi, Hyun Woo,Jang, Hyo Jin,Chung, Hyung Min,Arauzo-Bravo, Marcos J.,Schö,ler, Hans R.,Do, Jeong Tae The Company of Biologists Limited 2013 Journal of cell science Vol.126 No.11
<P>Induced pluripotent stem cells (iPSCs), generated from somatic cells by overexpression of transcription factors Oct4, Sox2, Klf4 and c-Myc have the same characteristics as pluripotent embryonic stem cells (ESCs). iPSCs reprogrammed from differentiated cells undergo epigenetic modification during reprogramming, and ultimately acquire a similar epigenetic state to that of ESCs. In this study, these epigenetic changes were observed in reprogramming of uniparental parthenogenetic somatic cells. The parthenogenetic pattern of imprinted genes changes during the generation of parthenogenetic maternal iPSCs (miPSCs), a process referred to as pluripotent reprogramming. We determined whether altered imprinted genes are maintained or revert to the parthenogenetic state when the reprogrammed cells are redifferentiated into specialized cell types. To address this question, we redifferentiated miPSCs into neural stem cells (miPS-NSCs) and compared them with biparental female NSCs (fNSCs) and parthenogenetic NSCs (pNSCs). We found that pluripotent reprogramming of parthenogenetic somatic cells could reset parthenogenetic DNA methylation patterns in imprinted genes, and that alterations in DNA methylation were maintained even after miPSCs were redifferentiated into miPS-NSCs. Notably, maternally methylated imprinted genes (<I>Peg1</I>, <I>Peg3</I>, <I>Igf2r</I>, <I>Snrpn</I> and <I>Ndn</I>), whose differentially methylated regions were fully methylated in pNSCs, were demethylated and their expression levels were found to be close to the levels in normal biparental fNSCs after reprogramming and redifferentiation. Our findings suggest that pluripotent reprogramming of parthenogenetic somatic cells followed by redifferentiation leads to changes in DNA methylation of imprinted genes and the reestablishment of gene expression levels to those of normal biparental cells.</P>
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Direct Reprogramming of Fibroblasts into Neural Stem Cells by Defined Factors
Han, D.,Tapia, N.,Hermann, A.,Hemmer, K.,Hoing, S.,Arauzo-Bravo, Marcos J.,Zaehres, H.,Wu, G.,Frank, S.,Moritz, S.,Greber, B.,Yang, J.,Lee, H.,Schwamborn, Jens C.,Storch, A.,Scholer, Hans R. Cell Press 2012 Cell stem cell Vol.10 No.4
Recent studies have shown that defined sets of transcription factors can directly reprogram differentiated somatic cells to a different differentiated cell type without passing through a pluripotent state, but the restricted proliferative and lineage potential of the resulting cells limits the scope of their potential applications. Here we show that a combination of transcription factors (Brn4/Pou3f4, Sox2, Klf4, c-Myc, plus E47/Tcf3) induces mouse fibroblasts to directly acquire a neural stem cell identity-which we term as induced neural stem cells (iNSCs). Direct reprogramming of fibroblasts into iNSCs is a gradual process in which the donor transcriptional program is silenced over time. iNSCs exhibit cell morphology, gene expression, epigenetic features, differentiation potential, and self-renewing capacity, as well as in vitro and in vivo functionality similar to those of wild-type NSCs. We conclude that differentiated cells can be reprogrammed directly into specific somatic stem cell types by defined sets of specific transcription factors.
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