Investigating the role of Sirtuins in cell reprogramming

( Jaein Shin ),( Junyeop Kim ),( Hanseul Park ),( Jongpil Kim ) 생화학분자생물학회 2018 BMB Reports Vol.51 No.10

Cell reprogramming has been considered a powerful technique in the regenerative medicine field. In addition to diverse its strengths, cell reprogramming technology also has several drawbacks generated during the process of reprogramming. Telomere shortening caused by the cell reprogramming process impedes the efficiency of cell reprogramming. Transcription factors used for reprogramming alter genomic contents and result in genetic mutations. Additionally, defective mitochondria functioning such as excessive mitochondrial fission leads to the limitation of pluripotency and ultimately reduces the efficiency of reprogramming. These problems including genomic instability and impaired mitochondrial dynamics should be resolved to apply cell reprograming in clinical research and to address efficiency and safety concerns. Sirtuin (NAD+-dependent histone deacetylase) has been known to control the chromatin state of the telomere and influence mitochondria function in cells. Recently, several studies reported that Sirtuins could control for genomic instability in cell reprogramming. Here, we review recent findings regarding the role of Sirtuins in cell reprogramming. And we propose that the manipulation of Sirtuins may improve defects that result from the steps of cell reprogramming. [BMB Reports 2018; 51(10): 500-507]

Reactivation of the inactive X chromosome and post-transcriptional reprogramming of <i>Xist</i> in iPSCs

Kim, Jong Soo,Choi, Hyun Woo,Araú,zo-Bravo, Marcos J.,Schö,ler, Hans R.,Do, Jeong Tae The Company of Biologists Ltd. 2015 Journal of cell science Vol.128 No.1

<P>Direct reprogramming of somatic cells to pluripotent stem cells entails the obliteration of somatic cell memory and the reestablishment of epigenetic events. Induced pluripotent stem cells (iPSCs) have been created by reprogramming somatic cells through the transduction of reprogramming factors. During cell reprogramming, female somatic cells must overcome at least one more barrier than male somatic cells in order to enter a pluripotent state, as they must reactivate an inactive X chromosome (Xi). In this study, we investigated whether the sex of somatic cells affects reprogramming efficiency, differentiation potential and the post-transcriptional processing of <I>Xist</I> RNA after reprogramming. There were no differences between male and female iPSCs with respect to reprogramming efficiency or their differentiation potential <I>in vivo</I>. However, reactivating Xi took longer than reactivating pluripotency-related genes. We also found that direct reprogramming leads to gender-appropriate post-transcriptional reprogramming – like male embryonic stem cells (ESCs), male iPSCs expressed only the long <I>Xist</I> isoform, whereas female iPSCs, like female ESCs, expressed both the long and short isoforms.</P>

Rad51 Regulates Reprogramming Efficiency through DNA Repair Pathway

Jae-Young Lee,Dae-Kwan Kim,Jeong-Jae Ko,Keun Pil Kim,Kyung-Soon Park 한국발생생물학회 2016 발생과 생식 Vol.20 No.2

Rad51 is a key component of homologous recombination (HR) to repair DNA double-strand breaks and it forms Rad51 recombinase filaments of broken single-stranded DNA to promote HR. In addition to its role in DNA repair and cell cycle progression, Rad51 contributes to the reprogramming process during the generation of induced pluripotent stem cells. In light of this, we performed reprogramming experiments to examine the effect of co-expression of Rad51 and four reprogramming factors, Oct4, Sox2, Klf4, and c-Myc, on the reprogramming efficiency. Co-expression of Rad51 significantly increased the numbers of alkaline phosphatase-positive colonies and embryonic stem cell-like colonies during the process of reprogramming. Co-expression ofRad51 significantly increased the expression of epithelial markers at an early stage of reprogramming compared with control cells. Phosphorylated histone H2AX (γH2AX), which initiates the DNA double-strand break repair system, was highly accumulated in reprogramming intermediates upon co-expression of Rad51. This study identified a novel role of Rad51 in enhancing the reprogramming efficiency, possibly by facilitating mesenchymal-to-epithelial transition and by regulating a DNA damage repair pathway during the early phase of the reprogramming process.

Establishment of Hepatocellular Cancer Induced Pluripotent Stem Cells Using a Reprogramming Technique

( Han Joon Kim ),( Jaemin Jeong ),( Sunhoo Park ),( Young-woo Jin ),( Seung-sook Lee ),( Seung Bum Lee ),( Dongho Choi ) 대한소화기학회 2017 Gut and Liver Vol.11 No.2

Background/Aims: Cancer is known to be a disease by many factors. However, specific results of reprogramming by pluripotency-related transcription factors remain to be scarcely reported. Here, we verified potential effects of pluripotent-related genes in hepatocellular carcinoma cancer cells. Methods: To better understand reprogramming of cancer cells in different genetic backgrounds, we used four liver cancer cell lines representing different states of p53 (HepG2, Hep3B, Huh7 and PLC). Retroviral-mediated introduction of reprogramming related genes (KLF4, Oct4, Sox2, and Myc) was used to induce the expression of proteins related to a pluripotent status in liver cancer cells. Results: Hep3B cells (null p53) exhibited a higher efficiency of reprogramming in comparison to the other liver cancer cell lines. The reprogrammed Hep3B cells acquired similar characteristics to pluripotent stem cells. However, loss of stemness in Hep3B-iPCs was detected during continual passage. Conclusions: We demonstrated that reprogramming was achieved in tumor cells through retroviral induction of genes associated with reprogramming. Interestingly, the reprogrammed pluripotent cancer cells (iPCs) were very different from original cancer cells in terms of colony shape and expressed markers. The induction of pluripotency of liver cancer cells correlated with the status of p53, suggesting that different expression level of p53 in cancer cells may affect their reprogramming. (Gut Liver 2017;11:261-269)

줄기세포와 생식세포에서 리프로그래밍 인자에 대한 최근 연구 동향과 전망

서유미,이경아 한국발생생물학회 2010 발생과 생식 Vol.14 No.2

Recently induced pluripotent stem (iPS) cells are derived from somatic cells by ectopic expression of several transcription factors (reprogramming factors) using technology of somatic cell reprogramming. iPS cells are able to self- renew and differentiate into all type of cells in the body similarly to embryonic stem cells. Because iPS cells have advantages that can avoid immune rejection after transplantation and ethical issues unlike embryonic stem cells, research on iPS has made significant progress since the first report by Yamanaka in 2006. Nevertheless of many advantages of iPS, safer methods to introduce reprogramming factors into somatic cells must be developed due to safety concerns regarding viral vectors, and safer reprogramming factors to substitute the oncogenes should be evaluated for clinical application of iPS. Here we discuss the recent progress in reprogramming factors in embryonic stem cells, oocytes, and embryos, and discuss further research for finding new, more reliable and safer reprogramming factors.

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>

Direct reprogramming and biomaterials for controlling cell fate

Eunsol Kim,태기융 한국생체재료학회 2016 생체재료학회지 Vol.20 No.4

Direct reprogramming which changes the fate of matured cell is a very useful technique with a great interest recently. This approach can eliminate the drawbacks of direct usage of stem cells and allow the patient specific treatment in regenerative medicine. Overexpression of diverse factors such as general reprogramming factors or lineage specific transcription factors can change the fate of already differentiated cells. On the other hand, biomaterials can provide physical and topographical cues or biochemical cues on cells, which can dictate or significantly affect the differentiation of stem cells. The role of biomaterials on direct reprogramming has not been elucidated much, but will be potentially significant to improve the efficiency or specificity of direct reprogramming. In this review, the strategies for general direct reprogramming and biomaterials-guided stem cell differentiation are summarized with the addition of the up-to-date progress on biomaterials for direct reprogramming.

역분화줄기세포의 연구현황과 임상적용을 위한 과제

윤병선,유승권 대한의사협회 2011 대한의사협회지 Vol.54 No.5

The generation of induced pluripotent stem cells (iPSCs) from somatic cells demonstrated that adult mammalian cells can be reprogrammed into a pluripotent state by introducing defined transcription factors. iPSCs show almost identical properties in self-renewal and pluripotency, and can circumvent ethical concerns because they do not use embryonic materials. Therefore, iPSCs from a patient’s somatic cells have great potential in studying drug development and regenerative medicine. Several human disease models have already been established using patient-specific iPSCs from Parkinson’s disease and familial dysautonomia. Moreover, the correction of genetic defects by homologous recombination has already been accomplished with Fanconi anemia patient-specific iPSCs. However, the generation of patient-specific iPSCs for clinical application requires alternative strategies, because genome-integrating viral vectors may raise tumorigenic risk after transplantation. Moreover, the use of iPSCs for eventual clinical application is limited by the low efficiency of current methods for reprogramming. Studies on the mechanism underlying the reprogramming and on establishment of non-integration methods contribute evidence toward resolving the safety concerns associated with iPSCs. Small molecules involved in the epigenetic modification and signaling pathway not only improve reprogramming efficiencies, but also bypass the addition of certain reprogramming factors. However, reprogramming somatic cells purely by small molecule treatment still remains a challenge. Here, we review recent progress made by the use of transcription factors and small molecules that can either replace reprogramming factors or enhance reprogramming efficiency. We also discuss the progress that has been made in the rapidly moving iPSC field, with an emphasis on understanding the mechanisms of cellular reprogramming and its potential application to cell therapy.

AUTOMATIC NETWORK REPROGRAMMING FOR WIRELESS SENSOR NETWORKS

Dujdow Buranapanichkit 대한전자공학회 2007 ITC-CSCC :International Technical Conference on Ci Vol.2007 No.7

This paper presents an automatic approach on network reprogramming for wireless sensor network. Mostly network reprogramming provides protocol which transmits code update from source node to targeted receivers. We cannot identify the appropriate operation of sensor node in that area. So we perform setting trigger condition at sensor node for requesting to update the required code from source node as the suitable situation. Due to all of cases for reprogramming on wireless sensor networks, sensor nodes should be known its requirement. That is automatic network reprogramming based on trigger condition at sensor node will be helpful for robust and efficient network reprogramming.

Electrical stimulation facilitates differentiation of chemically induced cardiac spheroids

민성진,진윤희,김유흔,정은선,김수겸,김수연,조승우 한국공업화학회 2020 한국공업화학회 연구논문 초록집 Vol.2020 No.-

Direct reprogramming technique which converts somatic cells to other lineage cells has been attracting attention because this method can easily generate the desired cell types without using stem cells. However, there is still a need for improvement in reprogramming efficiency. Here, we generated 3D cardiac spheroids using direct reprogramming with small molecules. We confirmed that cardiac-specific markers were expressed in formed 3D spheroids and gene expression levels associated with cardiac differentiation were upregulated compared to 2D direct reprogramming. To further enhance reprogramming efficiency, we briefly screened the voltages which can facilitate 3D cardiac reprogramming and affect the beating of induced cardiac cells. Electrically stimulated spheroids showed upregulated cardiac gene expression compared with the ones without stimulation.