Dieter Egli

Columbia University, New York City, New York, United States

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Publications (47)667.56 Total impact

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    ABSTRACT: Defects in Membrane Frizzled-related Protein (MFRP) cause autosomal recessive retinitis pigmentosa (RP). MFRP codes for a retinal pigment epithelium (RPE)-specific membrane receptor of unknown function. In patient-specific induced pluripotent stem (iPS)-derived RPE cells, precise levels of MFRP, and its dicistronic partner CTRP5, are critical to the regulation of actin organization. Overexpression of CTRP5 in naïve human RPE cells phenocopied behavior of MFRP-deficient patient RPE (iPS-RPE) cells. AAV8 (Y733F) vector expressing human MFRP rescued the actin disorganization phenotype and restored apical microvilli in patient-specific iPS-RPE cell lines. As a result, AAV-treated MFRP mutant iPS-RPE recovered pigmentation and transepithelial resistance. The efficacy of AAV-mediated gene therapy was also evaluated in Mfrp(rd6)/Mfrp(rd6) mice-an established preclinical model of RP-and long-term improvement in visual function was observed in AAV-Mfrp treated mice. This report is the first to indicate the successful use of human iPS-RPE cells as a recipient for gene therapy. The observed favorable response to gene therapy in both patient-specific cell lines and the Mfrp(rd6)/Mfrp(rd6) preclinical model suggests that this form of degeneration caused by MFRP mutations is a potential target for interventional trials.Molecular Therapy (2014); doi:10.1038/mt.2014.100.
    Molecular therapy : the journal of the American Society of Gene Therapy. 06/2014;
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    ABSTRACT: Common polymorphisms in the first intron of FTO are associated with increased body weight in adults. Previous studies have suggested that a CUX1-regulatory element within the implicated FTO region controls expression of FTO and the nearby ciliary gene, RPGRIP1L. Given the role of ciliary genes in energy homeostasis, we hypothesized that mice hypomorphic for Rpgrip1l would display increased adiposity. We find that Rpgrip1l(+/-) mice are hyperphagic and fatter, and display diminished suppression of food intake in response to leptin administration. In the hypothalamus of Rpgrip1l(+/-) mice, and in human fibroblasts with hypomorphic mutations in RPGRIP1L, the number of AcIII-positive cilia is diminished, accompanied by impaired convening of the leptin receptor to the vicinity of the cilium, and diminished pStat3 in response to leptin. These findings suggest that RPGRIP1L may be partly or exclusively responsible for the obesity susceptibility signal at the FTO locus.
    Cell metabolism 05/2014; 19(5):767-79. · 17.35 Impact Factor
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    ABSTRACT: The transfer of somatic cell nuclei into oocytes can give rise to pluripotent stem cells that are consistently equivalent to embryonic stem cells, holding promise for autologous cell replacement therapy. Although methods to induce pluripotent stem cells from somatic cells by transcription factors are widely used in basic research, numerous differences between induced pluripotent stem cells and embryonic stem cells have been reported, potentially affecting their clinical use. Because of the therapeutic potential of diploid embryonic stem-cell lines derived from adult cells of diseased human subjects, we have systematically investigated the parameters affecting efficiency of blastocyst development and stem-cell derivation. Here we show that improvements to the oocyte activation protocol, including the use of both kinase and translation inhibitors, and cell culture in the presence of histone deacetylase inhibitors, promote development to the blastocyst stage. Developmental efficiency varied between oocyte donors, and was inversely related to the number of days of hormonal stimulation required for oocyte maturation, whereas the daily dose of gonadotropin or the total number of metaphase II oocytes retrieved did not affect developmental outcome. Because the use of concentrated Sendai virus for cell fusion induced an increase in intracellular calcium concentration, causing premature oocyte activation, we used diluted Sendai virus in calcium-free medium. Using this modified nuclear transfer protocol, we derived diploid pluripotent stem-cell lines from somatic cells of a newborn and, for the first time, an adult, a female with type 1 diabetes.
    Nature 04/2014; · 38.60 Impact Factor
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    ABSTRACT: While the past decade has seen great progress in mapping loci for common diseases, studying how these risk alleles lead to pathology remains a challenge. Age-related macular degeneration (AMD) affects nine million older Americans, and is characterized by loss of the retinal pigment epithelium (RPE). Although the closely linked genome-wide association studies (GWAS) ARMS2/HTRA1 genes, located at the chromosome 10q26 locus, are strongly associated with the risk of AMD, their downstream targets are unknown. Low population frequencies of risk alleles in tissue banks make it impractical to study their function in cells derived from autopsied tissue. Moreover, autopsy eyes from end-stage AMD patients, where age-related RPE atrophy and fibrosis are already present, cannot be used to determine how abnormal ARMS2/HTRA1 expression can initiate RPE pathology. Instead, induced pluripotent stem (iPS) cell-derived RPE from patients provides us with earlier stage AMD patient-specific cells and allows us to analyze the underlying mechanisms at this critical time point. An unbiased proteome screen of A2E-aged patient-specific iPS-derived RPE cell lines identified SOD2-mediated antioxidative defense in the genetic allele's susceptibility of AMD. The AMD-associated risk haplotype (T-in/del-A) impairs the ability of the RPE to defend against aging-related oxidative stress. SOD2 defense is impaired in RPE homozygous for the risk haplotype (T-in/del-A; T-in/del-A), while the effect was less pronounced in RPE homozygous for the protective haplotype (G-Wt-G; G-Wt-G). ARMS2/HTRA1 risk alleles decrease SOD2 defense, making RPE more susceptible to oxidative damage and thereby contributing to AMD pathogenesis.
    Human Molecular Genetics 02/2014; · 7.69 Impact Factor
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    ABSTRACT: Hyperphagia is a central feature of inherited disorders (e.g., Prader-Willi Syndrome) in which obesity is a primary phenotypic component. Hyperphagia may also contribute to obesity as observed in the general population, thus raising the potential importance of common underlying mechanisms and treatments. Substantial gaps in understanding the molecular basis of inherited hyperphagia syndromes are present as are a lack of mechanistic of mechanistic targets that can serve as a basis for pharmacologic and behavioral treatments. International conference with 28 experts, including scientists and caregivers, providing presentations, panel discussions, and debates. The reviewed collective research and clinical experience provides a critical body of new and novel information on hyperphagia at levels ranging from molecular to population. Gaps in understanding and tools needed for additional research were identified. This report documents the full scope of important topics reviewed at a comprehensive international meeting devoted to the topic of hyperphagia and identifies key areas for future funding and research.
    Obesity 02/2014; 22 Suppl 1:S1-S17. · 3.92 Impact Factor
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    ABSTRACT: Generation of surrogate sources of insulin-producing β-cells remains a goal of diabetes therapy. While most efforts have been directed at differentiating embryonic or induced pluripotent stem (iPS) cells into β-like-cells through endodermal progenitors, we have shown that gut endocrine progenitor cells of mice can be differentiated into glucose-responsive, insulin-producing cells by ablation of transcription factor Foxo1. Here we show that FOXO1 is present in human gut endocrine progenitor and serotonin-producing cells. Using gut organoids derived from human iPS cells, we show that FOXO1 inhibition using a dominant-negative mutant or lentivirus-encoded small hairpin RNA promotes generation of insulin-positive cells that express all markers of mature pancreatic β-cells, release C-peptide in response to secretagogues and survive in vivo following transplantation into mice. The findings raise the possibility of using gut-targeted FOXO1 inhibition or gut organoids as a source of insulin-producing cells to treat human diabetes.
    Nature Communications 01/2014; 5:4242. · 10.74 Impact Factor
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    Nature medicine 12/2013; 19(12):1578-9. · 27.14 Impact Factor
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    ABSTRACT: Wolfram syndrome is an autosomal recessive disorder caused by mutations in WFS1 and characterized by insulin-dependent diabetes mellitus, optic atrophy and deafness. To investigate the cause of beta cell failure, we used induced pluripotent stem (iPS) cells to create insulin-producing cells from individuals with Wolfram syndrome. WFS1-deficient beta cells showed increased levels of endoplasmic reticulum (ER) stress molecules, and decreased insulin content. Upon exposure to experimental ER stress, Wolfram beta cells showed impaired insulin processing and failed to increase insulin secretion in response to glucose and other secretagogues. Importantly, 4-phenyl butyric acid, a chemical protein folding and trafficking chaperone, restored normal insulin synthesis and the ability to upregulate insulin secretion. These studies show that ER stress plays a central role in beta cell failure in Wolfram syndrome and indicate that chemical chaperones might have therapeutic relevance under conditions of ER stress in Wolfram syndrome and other forms of diabetes.
    Diabetes 11/2013; · 7.90 Impact Factor
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    ABSTRACT: ATP-dependent chromatin remodelers control DNA access for transcription, recombination, and other processes. Acf1 (also known as BAZ1A in mammals) is a defining subunit of the conserved ISWI-family chromatin remodelers ACF and CHRAC, first purified over 15 years ago from Drosophila melanogaster embryos. Much is known about biochemical properties of ACF and CHRAC, which move nucleosomes in vitro and in vivo to establish ordered chromatin arrays. Genetic studies in yeast, flies and cultured human cells clearly implicate these complexes in transcriptional repression via control of chromatin structures. RNAi experiments in transformed mammalian cells in culture also implicate ACF and CHRAC in DNA damage checkpoints and double-strand break repair. However, their essential in vivo roles in mammals are unknown. Here, we show that Baz1a-knockout mice are viable and able to repair developmentally programmed DNA double-strand breaks in the immune system and germ line, I-SceI endonuclease-induced breaks in primary fibroblasts via homologous recombination, and DNA damage from mitomycin C exposure in vivo. However, Baz1a deficiency causes male-specific sterility in accord with its high expression in male germ cells, where it displays dynamic, stage-specific patterns of chromosomal localization. Sterility is caused by pronounced defects in sperm development, most likely a consequence of massively perturbed gene expression in spermatocytes and round spermatids in the absence of BAZ1A: the normal spermiogenic transcription program is largely intact but more than 900 other genes are mis-regulated, primarily reflecting inappropriate up-regulation. We propose that large-scale changes in chromatin composition that occur during spermatogenesis create a window of vulnerability to promiscuous transcription changes, with an essential function of ACF and/or CHRAC chromatin remodeling activities being to safeguard against these alterations.
    PLoS Genetics 11/2013; 9(11):e1003945. · 8.52 Impact Factor
  • Gloryn Chia, Dieter Egli
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    ABSTRACT: Abstract The remarkable ability of oocytes to reinstate the totipotent state from a unipotent somatic cell, allowing the cloning of animals and the generation of human stem cells, has fascinated scientists for decades. Due to the complexity of oocytes, it has remained challenging to understand the rapid reprogramming following nuclear transfer at a molecular level. Conversely, the detailed characterization of molecular mechanisms is also often insufficient to comprehend the functional relevance of a complex molecular process, such as the dissociation of transcription factors from chromatin during cell division, the role of chromatin modifications in cellular memory, or of cell type-specific DNA replication. This review attempts to bridge the gap between nuclear transfer and molecular biology by focusing on the role of the cell cycle in reprogramming.
    Cellular reprogramming. 10/2013; 15(5):356-66.
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    ABSTRACT: Diabetes is a disorder characterized by loss of β cell mass and/or β cell function, leading to deficiency of insulin relative to metabolic need. To determine whether stem cell-derived β cells recapitulate molecular-physiological phenotypes of a diabetic subject, we generated induced pluripotent stem cells (iPSCs) from subjects with maturity-onset diabetes of the young type 2 (MODY2), which is characterized by heterozygous loss of function of the gene encoding glucokinase (GCK). These stem cells differentiated into β cells with efficiency comparable to that of controls and expressed markers of mature β cells, including urocortin-3 and zinc transporter 8, upon transplantation into mice. While insulin secretion in response to arginine or other secretagogues was identical to that in cells from healthy controls, GCK mutant β cells required higher glucose levels to stimulate insulin secretion. Importantly, this glucose-specific phenotype was fully reverted upon gene sequence correction by homologous recombination. Our results demonstrate that iPSC-derived β cells reflect β cell-autonomous phenotypes of MODY2 subjects, providing a platform for mechanistic analysis of specific genotypes on β cell function.
    The Journal of clinical investigation 06/2013; · 15.39 Impact Factor
  • Dieter Egli, Gloryn Chia Le Bin
    Nature Reviews Molecular Cell Biology 05/2013; 14(6):326. · 37.16 Impact Factor
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    ABSTRACT: Current methods to derive induced pluripotent stem cell (iPSC) lines from human dermal fibroblasts by viral infection rely on expensive and lengthy protocols. One major factor contributing to the time required to derive lines is the ability of researchers to identify fully reprogrammed unique candidate clones from a mixed cell population containing transformed or partially reprogrammed cells and fibroblasts at an early time point post infection. Failure to select high quality colonies early in the derivation process results in cell lines that require increased maintenance and unreliable experimental outcomes. Here, we describe an improved method for the derivation of iPSC lines using fluorescence activated cell sorting (FACS) to isolate single cells expressing the cell surface marker signature CD13(NEG)SSEA4(POS)Tra-1-60(POS) on day 7-10 after infection. This technique prospectively isolates fully reprogrammed iPSCs, and depletes both parental and "contaminating" partially reprogrammed fibroblasts, thereby substantially reducing the time and reagents required to generate iPSC lines without the use of defined small molecule cocktails. FACS derived iPSC lines express common markers of pluripotency, and possess spontaneous differentiation potential in vitro and in vivo. To demonstrate the suitability of FACS for high-throughput iPSC generation, we derived 228 individual iPSC lines using either integrating (retroviral) or non- integrating (Sendai virus) reprogramming vectors and performed extensive characterization on a subset of those lines. The iPSC lines used in this study were derived from 76 unique samples from a variety of tissue sources, including fresh or frozen fibroblasts generated from biopsies harvested from healthy or disease patients.
    PLoS ONE 01/2013; 8(3):e59867. · 3.53 Impact Factor
  • Mitochondrion 01/2013; 13(6):898–899. · 4.03 Impact Factor
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    ABSTRACT: Mitochondrial DNA mutations transmitted maternally within the oocyte cytoplasm often cause life-threatening disorders. Here we explore the use of nuclear genome transfer between unfertilized oocytes of two donors to prevent the transmission of mitochondrial mutations. Nuclear genome transfer did not reduce developmental efficiency to the blastocyst stage, and genome integrity was maintained provided that spontaneous oocyte activation was avoided through the transfer of incompletely assembled spindle-chromosome complexes. Mitochondrial DNA transferred with the nuclear genome was initially detected at levels below 1%, decreasing in blastocysts and stem-cell lines to undetectable levels, and remained undetectable after passaging for more than one year, clonal expansion, differentiation into neurons, cardiomyocytes or β-cells, and after cellular reprogramming. Stem cells and differentiated cells had mitochondrial respiratory chain enzyme activities and oxygen consumption rates indistinguishable from controls. These results demonstrate the potential of nuclear genome transfer to prevent the transmission of mitochondrial disorders in humans.
    Nature 12/2012; · 38.60 Impact Factor
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    ABSTRACT: Objective: Parthenogenesis using calcium ionophore/ionomycin of matured metaphase II (MII) human oocytes have been shown to reach the blastocyst stage (Paffoni, 2007). Our experiment investigated the artificial activation of late maturing MIIs, collected and activated on either the day of vaginal oocyte retrieval (VOR) or on Day 1 (D1). Comparisons of cleavage rates were tracked. This study exams the developmental potential of these normally discarded oocytes. Design: Prospective comparison of parthenogenetic development in late maturing oocytes
    Fertility and sterility 10/2012; 98(35):S21. · 3.97 Impact Factor
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    ABSTRACT: Enucleated oocytes have the distinctive ability to reprogram somatic nuclei back to totipotency. Here, we investigate genome-scale DNA methylation patterns after nuclear transfer and compare them to the dynamics at fertilization. We identify specific targets for DNA demethylation after nuclear transfer, such as germline-associated promoters, as well as unique limitations that include certain repetitive element classes.
    Nature Genetics 08/2012; 44(9):978-80. · 35.21 Impact Factor
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    ABSTRACT: The Food and Drug Administration has recently approved phase I/II clinical trials for ES cell-based retinal pigmented epithelium (RPE) transplantation, but this allograft transplantation requires life-long immunosuppressive therapy. Autografts from patient-specific induced pluripotent stem (iPS) cells offer an alternative solution to this problem. However, more data is required to establish the safety and efficacy of iPS transplantation in animal models before moving iPS therapy into clinical trials. This study examines the efficacy of iPS transplantation in restoring functional vision in Rpe65(rd12)/Rpe65(rd12) mice, a clinically-relevant model of retinitis pigmentosa (RP). Human iPS cells were differentiated into morphologically and functionally RPE-like tissue. Quantitative real-time PCR and immunoblots confirmed RPE fate. The iPS-derived RPE cells were injected into the subretinal space of Rpe65(rd12)/Rpe65(rd12) mice at two days postnatally. After transplantation, the long-term surviving iPS-derived RPE graft colocalized with the host native RPE cells and assimilated into the host retina without disruption. None of the mice receiving transplants developed tumors over their lifetimes. Furthermore, electroretinography (ERG), a standard method for measuring efficacy in human trials, demonstrated improved visual function in recipients over the lifetime of this RP mouse model. Our study provides the first direct evidence of functional recovery in a clinically relevant model of retinal degeneration using iPS transplantation and supports the feasibility of autologous iPS cell transplantation for retinal and macular degenerations featuring significant RPE loss.
    Molecular Medicine 08/2012; · 4.47 Impact Factor
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    ABSTRACT: Germline mutations of the breast cancer 1 (BRCA1) gene are a major cause of familial breast and ovarian cancer. The BRCA1 protein displays E3 ubiquitin ligase activity, and this enzymatic function is thought to be required for tumor suppression. To test this hypothesis, we generated mice that express an enzymatically defective Brca1. We found that this mutant Brca1 prevents tumor formation to the same degree as does wild-type Brca1 in three different genetically engineered mouse (GEM) models of cancer. In contrast, a mutation that ablates phosphoprotein recognition by the BRCA C terminus (BRCT) domains of BRCA1 elicits tumors in each of the three GEM models. Thus, BRCT phosphoprotein recognition, but not the E3 ligase activity, is required for BRCA1 tumor suppression.
    Science 10/2011; 334(6055):525-8. · 31.20 Impact Factor
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    ABSTRACT: The exchange of the oocyte's genome with the genome of a somatic cell, followed by the derivation of pluripotent stem cells, could enable the generation of specific cells affected in degenerative human diseases. Such cells, carrying the patient's genome, might be useful for cell replacement. Here we report that the development of human oocytes after genome exchange arrests at late cleavage stages in association with transcriptional abnormalities. In contrast, if the oocyte genome is not removed and the somatic cell genome is merely added, the resultant triploid cells develop to the blastocyst stage. Stem cell lines derived from these blastocysts differentiate into cell types of all three germ layers, and a pluripotent gene expression program is established on the genome derived from the somatic cell. This result demonstrates the feasibility of reprogramming human cells using oocytes and identifies removal of the oocyte genome as the primary cause of developmental failure after genome exchange.
    Nature 10/2011; 478(7367):70-5. · 38.60 Impact Factor

Publication Stats

2k Citations
667.56 Total Impact Points

Institutions

  • 2012–2014
    • Columbia University
      • • Department of Pediatrics
      • • Department of Ophthalmology
      New York City, New York, United States
    • The New York Stem Cell Foundation
      New York City, New York, United States
  • 2007–2011
    • Harvard University
      • • Department of Stem Cell and Regenerative Biology
      • • Department of Molecular and Cell Biology
      Cambridge, MA, United States
    • Chinese Academy of Sciences
      • Institute of Biophysics
      Peping, Beijing, China
  • 2003–2008
    • University of Zurich
      • Institut für Molekulare Biologie
      Zürich, ZH, Switzerland
  • 2006
    • Freie Universität Berlin
      • Institute of Chemistry and Biochemistry
      Berlin, Land Berlin, Germany