• BMB Reports
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• 제48권12호
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• pp.668-676
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• 2015

Pluripotent stem cells only exist in a narrow window during early embryonic development, whereas multipotent stem cells are abundant throughout embryonic development and are retainedin various adult tissues and organs. While pluripotent stem cell lines have been established from several species, including mouse, rat, and human, it is still challenging to establish stable multipotent stem cell lines from embryonic or adult tissues. Based on current knowledge, we anticipate that by manipulating extrinsic and intrinsic signaling pathways, most if not all types of stem cells can be maintained in a long-term culture. In this article, we summarize current culture conditions established for the long-term maintenance of authentic pluripotent and multipotent stem cells and the signaling pathways involved. We also discuss the general principles of stem cell maintenance and propose several strategies on the establishment of novel stem cell lines through manipulation of signaling pathways.

• BMB Reports
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• 제48권2호
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• pp.68-80
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• 2015

G protein-coupled receptors (GPCRs) are a large class of transmembrane receptors categorized into five distinct families: rhodopsin, secretin, adhesion, glutamate, and frizzled. They bind and regulate 80% of all hormones and account for 20-50% of the pharmaceuticals currently on the market. Hundreds of GPCRs integrate and coordinate the functions of individual cells, mediating signaling between various organs. GPCRs are crucial players in tumor progression, adipogenesis, and inflammation. Several studies have also confirmed their central roles in embryonic development and stem cell maintenance. Recently, GPCRs have emerged as key players in the regulation of cell survival, proliferation, migration, and self-renewal in pluripotent (PSCs) and cancer stem cells (CSCs). Our study and other reports have revealed that the expression of many GPCRs is modulated during the generation of induced PSCs (iPSCs) or CSCs as well as during CSC sphere formation. These GPCRs may have crucial roles in the regulation of self-renewal and other biological properties of iPSCs and CSCs. This review addresses the current understanding of the role of GPCRs in stem cell maintenance and somatic reprogramming to PSCs or CSCs.

• International Journal of Stem Cells
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• 제16권1호
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• pp.44-51
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• 2023

Background and Objectives: DNA methyltransferases (Dnmts) play an important role in regulating DNA methylation during early developmental processes and cellular differentiation. In this study, we aimed to investigate the role of Dnmts in neural differentiation of embryonic stem cells (ESCs) and in maintenance of the resulting neural stem cells (NSCs). Methods and Results: We used three types of Dnmt knockout (KO) ESCs, including Dnmt1 KO, Dnmt3a/3b double KO (Dnmt3 DKO), and Dnmt1/3a/3b triple KO (Dnmt TKO), to investigate the role of Dnmts in neural differentiation of ESCs. All three types of Dnmt KO ESCs could form neural rosette and differentiate into NSCs in vitro. Interestingly, however, after passage three, Dnmt KO ESC-derived NSCs could not maintain their self-renewal and differentiated into neurons and glial cells. Conclusions: Taken together, the data suggested that, although deficiency of Dnmts had no effect on the differentiation of ESCs into NSCs, the latter had defective maintenance, thereby indicating that Dnmts are crucial for self-renewal of NSCs.

• BMB Reports
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• 제50권3호
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• pp.138-143
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• 2017

Ovariectomy-induced bone loss is related to an increased deposition of osteoclasts on bone surfaces. We reported that the 36-amino-acid-long neuropeptide Y (NPY) could mobilize hematopoietic stem/progenitor cells (HSPCs) from the bone marrow to the peripheral blood by regulating HSPC maintenance factors and that mobilization of HSPCs ameliorated low bone density in an ovariectomy-induced osteoporosis mouse model by reducing the number of osteoclasts. Here, we demonstrated that new NPY peptides, recombined from the cleavage of the full-length NPY, showed better functionality for HSPC mobilization than the full-length peptide. These recombinant peptides mediated HSPC mobilization with greater efficiency by decreasing HSPC maintenance factors. Furthermore, treatment with these peptides reduced the number of osteoclasts and relieved ovariectomy-induced bone loss in mice more effectively than treatment with full-length NPY. Therefore, these results suggest that peptides recombined from full-length NPY can be used to treat osteoporosis.

• International Journal of Stem Cells
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• 제16권3호
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• pp.293-303
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• 2023

Background and Objectives: The physiological oxygen tension in fetal brains (~3%, physioxia) is beneficial for the maintenance of neural stem cells (NSCs). Sensitivity to oxygen varies between NSCs from different fetal brain regions, with midbrain NSCs showing selective susceptibility. Data on Hif-1𝛼/Notch regulatory interactions as well as our observations that Hif-1𝛼 and oxygen affect midbrain NSCs survival and proliferation prompted our investigations on involvement of Notch signalling in physioxia-dependent midbrain NSCs performance. Methods and Results: Here we found that physioxia (3% O₂) compared to normoxia (21% O₂) increased proliferation, maintained stemness by suppression of spontaneous differentiation and supported cell cycle progression. Microarray and qRT-PCR analyses identified significant changes of Notch related genes in midbrain NSCs after long-term (13 days), but not after short-term physioxia (48 hours). Consistently, inhibition of Notch signalling with DAPT increased, but its stimulation with Dll4 decreased spontaneous differentiation into neurons solely under normoxic but not under physioxic conditions. Conclusions: Notch signalling does not influence the fate decision of midbrain NSCs cultured in vitro in physioxia, where other factors like Hif-1𝛼 might be involved. Our findings on how physioxia effects in midbrain NSCs are transduced by alternative signalling might, at least in part, explain their selective susceptibility to oxygen.

• BMB Reports
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• 제51권2호
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• pp.92-97
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• 2018

B cell leukemia/lymphoma 3 (Bcl3) plays a pivotal role in immune homeostasis, cellular proliferation, and cell survival, as a co-activator or co-repressor of transcription of the $NF-{\kappa}B$ family. Recently, it was reported that Bcl3 positively regulates pluripotency genes, including Oct4, in mouse embryonic stem cells (mESCs). However, the role of Bcl3 in the maintenance of pluripotency and self-renewal activity is not fully established. Here, we report the dynamic regulation of the proliferation, pluripotency, and self-renewal of mESCs by Bcl3 via an influence on Nanog transcriptional activity. Bcl3 expression is predominantly observed in immature mESCs, but significantly decreased during cell differentiation by LIF depletion and in mESC-derived EBs. Importantly, the knockdown of Bcl3 resulted in the loss of self-renewal ability and decreased cell proliferation. Similarly, the ectopic expression of Bcl3 also resulted in a significant reduction of proliferation, and the self-renewal of mESCs was demonstrated by alkaline phosphatase staining and clonogenic single cell-derived colony assay. We further examined that Bcl3-mediated regulation of Nanog transcriptional activity in mESCs, which indicated that Bcl3 acts as a transcriptional repressor of Nanog expression in mESCs. In conclusion, we demonstrated that a sufficient concentration of Bcl3 in mESCs plays a critical role in the maintenance of pluripotency and the self-renewal of mESCs via the regulation of Nanog transcriptional activity.

• Clinical and Experimental Reproductive Medicine
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• 제40권2호
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• pp.47-54
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• 2013

To overcome the difficulty of controlling stem cell fate and function in applications to regenerative medicine, a number of alternative approaches have been made. Recent reports demonstrate that a non-cellular niche modulating the biophysical microenvironment with chemical factors can support stem cell self-renewal. In our previous studies, early establishment was executed to optimize biophysical factors and it was subsequently found that the microgeometry of the extracellular matrix made huge differences in stem cell behavior and phenotype. We review here a three-dimensional, non-cellular niche designed to support stem cell self-renewal. The characteristics of stem cells under the designed system are further discussed.

• BMB Reports
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• 제48권12호
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• pp.655-667
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• 2015

Lineage tracing is a widely used method for understanding cellular dynamics in multicellular organisms during processes such as development, adult tissue maintenance, injury repair and tumorigenesis. Advances in tracing or tracking methods, from light microscopy-based live cell tracking to fluorescent label-tracing with two-photon microscopy, together with emerging tissue clearing strategies and intravital imaging approaches have enabled scientists to decipher adult stem and progenitor cell properties in various tissues and in a wide variety of biological processes. Although technical advances have enabled time-controlled genetic labeling and simultaneous live imaging, a number of obstacles still need to be overcome. In this review, we aim to provide an in-depth description of the traditional use of lineage tracing as well as current strategies and upcoming new methods of labeling and imaging.

• 한국발생생물학회지:발생과생식
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• 제19권3호
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• pp.119-126
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• 2015

The suitable feeder cell layer is important for culture of embryonic stem (ES) cells. In this study, we investigated the effect of two kinds of the feeder cell, MEF cells and STO cells, layer to mouse ES (mES) cell culture for maintenance of stemness. We compare the colony formations, alkaline phosphatase (AP) activities, expression of pluripotency marker genes and proteins of D3 cell colonies cultured on MEF feeder cell layer (D3/MEF) or STO cell layers (D3/STO) compared to feeder free condition (D3/-) as a control group. Although there were no differences to colony formations and AP activities, interestingly, the transcripts level of pluripotency marker genes, Pou5f1 and Nanog were highly expressed in D3/MEF (79 and 93) than D3/STO (61and 77) or D3/- (65 and 81). Also, pluripotency marker proteins, NANOG and SOX-2, were more synthesized in D3/MEF ($72.8{\pm}7.69$ and $81.2{\pm}3.56$) than D3/STO ($32.0{\pm}4.30$ and $56.0{\pm}4.90$) or D3/- ($55.0{\pm}4.64$ and $62.0{\pm}6.20$). These results suggest that MEF feeder cell layer is more suitable to mES cell culture.

• Molecules and Cells
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• 제27권6호
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• pp.615-620
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• 2009

The plant shoot meristem maintains a group of stem cells that remain active throughout the plant life. They continuously generate new cells that are then recruited for organ initiation in the peripheral zone. Stem cell proliferation and daughter cell differentiation has to be integrated with overall growth and development of the diverse functional domains within the shoot apex. Several studies have revealed extensive communication between these domains. The signaling mechanisms employed comprise diffusible peptides, directional transport of plant hormones, but also complex interactions between transcription factors, that together establish a panoply of regulatory inputs that fine-tune stem cell behavior in the shoot meristem.