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Human pluripotent stem cells (PSCs) are critical in vitro tools forbackslashnunderstanding mechanisms that regulate lineage differentiation inbackslashnthe human embryo as well as a potentially unlimited supply of stembackslashncells for regenerative medicine. Pluripotent human and mouse embryonicbackslashnstem cells (ESCs) derived from the inner cell mass of blastocystsbackslashnshare a similar transcription factor network to maintain pluripotencybackslashnand self-renewal,yet there are considerable molecular differencesbackslashnreflecting the diverse environments in which mouse and human ESCsbackslashnare derived. In the current study we evaluated the role of Proteinbackslashnarginine methyltransferase 5 (PRMT5) in human ESC (hESC) self-renewalbackslashnand pluripotency given its critical role in safeguarding mouse ESCbackslashnpluripotency. Unlike the mouse,we discovered that PRMT5 has no rolebackslashnin hESC pluripotency. Using microarray analysis we discovered thatbackslashna significant depletion in PRMT5 RNA and protein from hESCs changedbackslashnthe expression of only 78 genes,with the majority being repressed.backslashnFunctionally,we discovered that depletion of PRMT5 had no effectbackslashnon expression of OCT4,NANOG or SOX2,and did not prevent teratomabackslashnformation. Instead,we show that PRMT5 functions in hESCs to regulatebackslashnproliferation in the self-renewing state by regulating the fractionbackslashnof cells in Gap 1 (G1) of the cell cycle and increasing expressionbackslashnof the G1 cell cycle inhibitor P57. Taken together our data unveilsbackslashna distinct role for PRMT5 in hESCs and identifies P57 as new target. View Publication

Human embryonic stem cells (hESC) and hESC-derived cardiomyocytes (hESC-CM) hold great promise for the treatment of cardiovascular diseases. However the mechanobiological properties of hESC and hESC-CM remains elusive. In this paper,we examined the dynamic and static micromechanical properties of hESC and hESC-CM,by manipulating via optical tweezers at the single-cell level. Theoretical approaches were developed to model the dynamic and static mechanical responses of cells during optical stretching. Our experiments showed that the mechanical stiffness of differentiated hESC-CM increased after cardiac differentiation. Such stiffening could associate with increasingly organized myofibrillar assembly that underlines the functional characteristics of hESC-CM. In summary,our findings lay the ground work for using hESC-CMs as models to study mechanical and contractile defects in heart diseases. View Publication

Cardiovascular disease is a leading cause of death worldwide. The limited capability of heart tissue to regenerate has prompted methodological developments for creating de novo cardiomyocytes,both in vitro and in vivo. Beyond uses in cell replacement therapy,patient-specific cardiomyocytes may find applications in drug testing,drug discovery,and disease modeling. Recently,approaches for generating cardiomyocytes have expanded to encompass three major sources of starting cells: human pluripotent stem cells (hPSCs),adult heart-derived cardiac progenitor cells (CPCs),and reprogrammed fibroblasts. We discuss state-of-the-art methods for generating de novo cardiomyocytes from hPSCs and reprogrammed fibroblasts,highlighting potential applications and future challenges. View Publication

Despite significant advances in commercially available media and kits and the differentiation approaches for human neural stem cell (NSC) generation,NSC production from the differentiation of human pluripotent stem cell (hPSC) is complicated by its time-consuming procedure,complex medium composition,and purification step. In this study,we developed a convenient and simplified NSC production protocol to meet the demand of NSC production. We demonstrated that NSCs can be generated efficiently without requirement of specific small molecules or embryoid body formation stage. Our experimental results suggest that a short suspension culture period may facilitate ectoderm lineage specification rather than endoderm or mesoderm lineage specification from hPSCs. The method developed in this study shortens the turnaround time of NSC production from both human embryonic stem cells (hESCs) and induced pluripotent stem cells (iPSCs) differentiation. It provides a straightforward and useful strategy for generating NSCs that can benefit a wide range of research applications for human brain research. View Publication

Expression of genes associated with inflammation was analyzed during differentiation of human pluripotent stem cells (PSCs) to hepatic cells. Messenger RNA transcript profiles of differentiated endoderm (day 5),hepatoblast (day 15) and hepatocyte-like cells (day 21) were obtained by RNA sequencing analysis. When compared to endoderm cells an immature cell type,the hepatic cells (days 15 and 21) had significantly higher expression of acute phase protein genes including complement factors,coagulation factors,serum amyloid A and serpins. Furthermore,hepatic phase of cells expressed proinflammatory cytokines IL18 and IL32 as well as cytokine receptors IL18R1,IL1R1,IL1RAP,IL2RG,IL6R,IL6ST and IL10RB. These cells also produced CCL14,CCL15,and CXCL- 1,2,3,16 and 17 chemokines. Endoderm cells had higher levels of chemokine receptors,CXCR4 and CXCR7,than that of hepatic cells. Sirtuin family of genes involved in aging,inflammation and metabolism were differentially regulated in endoderm and hepatic phase cells. Ligands and receptors of the tumor necrosis factor (TNF) family as well as downstream signaling factors TRAF2,TRAF4,FADD,NFKB1 and NFKBIB were differentially expressed during hepatic differentiation. View Publication

FTIR micro-spectroscopy is a sensitive,non-destructive and label-free method offering diffraction-limited resolution with high signal-to-noise ratios when combined with a synchrotron radiation source. The vibrational signature of individual cells was used to validate an alternative strategy for reprogramming induced pluripotent stem cells generated from amniocytes. The iPSC lines PB09 and PB10,were reprogrammed from the same amniocyte cell line using respectively the Oct54,Sox2,Lin28,and Nanog and the Oct4 and Sox2 transcription factor cocktail. We show that cells reprogrammed by the two different sets of transfection factors have similar spectral signatures after reprogramming,except for a small subpopulation of cells in one of the cell lines. Mapping HeLa cells at subcellular resolution,we show that the Golgi apparatus,the cytoplasm and the nucleus have a specific spectral signature. The CH(3):CH(2) ratio is the highest in the nucleus and the lowest in the Golgi apparatus/endoplasmic reticulum,in agreement with the membrane composition of these organelles. This is confirmed by specific staining of the organelles with fluorescent dyes. Subcellular differentiation of cell compartments is also demonstrated in living cells. View Publication

The purpose of this study is to characterize the microRNA (miRNA) expression profiles of induced pluripotent stem (iPS) cells and retinal pigment epithelium (RPE) derived from induced pluripotent stem cells (iPS-RPE). MiRNAs have been demonstrated to play critical roles in both maintaining pluripotency and facilitating differentiation. Gene expression networks accountable for maintenance and induction of pluripotency are linked and share components with those networks implicated in oncogenesis. Therefore,we hypothesize that miRNA expression profiling will distinguish iPS cells from their iPS-RPE progeny. To identify and analyze differentially expressed miRNAs,RPE was derived from iPS using a spontaneous differentiation method. MiRNA microarray analysis identified 155 probes that were statistically differentially expressed between iPS and iPS-RPE cells. Up-regulated miRNAs including miR-181c and miR-129-5p may play a role in promoting differentiation,while down-regulated miRNAs such as miR-367,miR-18b,and miR-20b are implicated in cell proliferation. Subsequent miRNA-target and network analysis revealed that these miRNAs are involved in cellular development,cell cycle progression,cell death,and survival. A systematic interrogation of temporal and spatial expression of iPS-RPE miRNAs and their associated target mRNAs will provide new insights into the molecular mechanisms of carcinogenesis,eye differentiation and development. View Publication

The utility of human pluripotent stem cells is dependent on efficient differentiation protocols that convert these cells into relevant adult cell types. Here we report the robust and efficient differentiation of human pluripotent stem cells into white or brown adipocytes. We found that inducible expression of PPARG2 alone or combined with CEBPB and/or PRDM16 in mesenchymal progenitor cells derived from pluripotent stem cells programmed their development towards a white or brown adipocyte cell fate with efficiencies of 85%-90%. These adipocytes retained their identity independent of transgene expression,could be maintained in culture for several weeks,expressed mature markers and had mature functional properties such as lipid catabolism and insulin-responsiveness. When transplanted into mice,the programmed cells gave rise to ectopic fat pads with the morphological and functional characteristics of white or brown adipose tissue. These results indicate that the cells could be used to faithfully model human disease View Publication

The pressing demand to elucidate the biology of human embryonic stem (ES) cells and to realize their therapeutic potential has greatly promoted the progresses in the optimization of the culture systems used for this highly promising cell type. These progresses include the characterization of exogenous regulators of pluripotency and differentiation,the development of animal-free,defined,and scalable culture systems,and some pioneering efforts to establish good manufactory practice facilities to derive and expand clinical-grade human ES cells and their derivatives. All of these advancements appear to be also applicable to the derivation and culture of human induced pluripotent stem cells,an ES cell-like cell type derived from somatic cells via reprogramming. This review attempts to summarize these progresses and discuss some of the remaining challenges. View Publication

Nuclear-architecture defects have been shown to correlate with the manifestation of a number of human diseases as well as ageing. It is therefore plausible that diseases whose manifestations correlate with ageing might be connected to the appearance of nuclear aberrations over time. We decided to evaluate nuclear organization in the context of ageing-associated disorders by focusing on a leucine-rich repeat kinase 2 (LRRK2) dominant mutation (G2019S; glycine-to-serine substitution at amino acid 2019),which is associated with familial and sporadic Parkinson's disease as well as impairment of adult neurogenesis in mice. Here we report on the generation of induced pluripotent stem cells (iPSCs) derived from Parkinson's disease patients and the implications of LRRK2(G2019S) mutation in human neural-stem-cell (NSC) populations. Mutant NSCs showed increased susceptibility to proteasomal stress as well as passage-dependent deficiencies in nuclear-envelope organization,clonal expansion and neuronal differentiation. Disease phenotypes were rescued by targeted correction of the LRRK2(G2019S) mutation with its wild-type counterpart in Parkinson's disease iPSCs and were recapitulated after targeted knock-in of the LRRK2(G2019S) mutation in human embryonic stem cells. Analysis of human brain tissue showed nuclear-envelope impairment in clinically diagnosed Parkinson's disease patients. Together,our results identify the nucleus as a previously unknown cellular organelle in Parkinson's disease pathology and may help to open new avenues for Parkinson's disease diagnoses as well as for the potential development of therapeutics targeting this fundamental cell structure. View Publication

There is ample evidence that the ubiquitin-proteasome system is an important regulator of transcription and its activity is necessary for maintaining pluripotency and promoting cellular reprogramming. Moreover,proteasome activity contributes to maintaining the open chromatin structure found in pluripotent stem cells,acting as a transcriptional inhibitor at specific gene loci generally associated with differentiation. The current study was designed to understand further the role of proteasome inhibition in reprogramming and its ability to modulate endogenous expression of pluripotency-related genes and induced pluripotent stem cells (iPSCs) colony formation. Herein,we demonstrate that acute combinatorial treatment with the proteasome inhibitors MG101 or MG132 and the histone deacetylase (HDAC) inhibitor valproic acid (VPA) increases gene expression of the pluripotency marker Oct3/4,and that MG101 alone is as effective as VPA in the induction of Oct3/4 mRNA expression in fibroblasts. Prolonged proteasome inhibition cyclically upregulates gene expression of Oct3/4 and Nanog,but reduces colony formation in the presence of the iPSC induction cocktail. In conclusion,our results demonstrate that the 26S proteasome is an essential modulator in the reprogramming process. Its inhibition enhances expression of pluripotency-related genes; however,efficient colony formation requires proteasome activity. Therefore,discovery of small molecules that increase proteasome activity might lead to more efficient cell reprogramming and generation of pluripotent cells. View Publication

OBJECTIVE The KLF4 gene has been shown to be inactivated in cervical carcinogenesis as a tumor suppressor. However,the mechanism of KLF4 silencing in cervical carcinomas has not yet been identified. DNA methylation plays a key role in stable suppression of gene expression. METHODS The methylation status of the KLF4 promoter CpG islands was analyzed by bisulfite sequencing (BSQ) in tissues of normal cervix and cervical cancer. KLF4 gene expression was detected by RT-PCR,immunohistochemistry and western blot. KLF4 promoter methylation in cervical cancer cell line was determined by BSQ and methylation-specific polymerase chain reaction (MS-PCR). Cell proliferation ability was detected by cell growth curve and MTT assay. RESULTS The methylated allele was found in 41.90% of 24 cervical cancer tissues but only in 11.11% of 11 normal cervix tissues (Ptextless0.005). KLF4 mRNA levels were significantly reduced in cervical cancer tissues compared with normal cervix tissues (Ptextless0.01) and KLF4 mRNA expression showed a significant negative correlation with the promoter hypermethylation (r = -0.486,P = 0.003). Cervical cancer cell lines also showed a significant negative correlation between KLF4 expression and hypermethylation. After treatment with the demethylating agent 5-Azacytidine (5-Aza),the expression of KLF4 in the cervical cancer cell lines at both mRNA and protein levels was drastically increased,the cell proliferation ability was inhibited and the chemosensitivity for cisplatin was significantly increased. CONCLUSION KLF4 gene is inactivated by methylation-induced silencing mechanisms in a large subset of cervical carcinomas and KLF4 promoter hypermethylation inactivates the gene's function as a tumor suppressor in cervical carcinogenesis. View Publication