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Publications in Biomedical Research by NOMIS researchers

Reprogramming of human fibroblasts to pluripotency with lineage specifiers

NOMIS Researcher(s)

Published in

September 5, 2013

Since the initial discovery that OCT4, SOX2, KLF4, and c-MYC overexpression sufficed for the induction of pluripotency in somatic cells, methodologies replacing the original factors have enhanced our understanding of the reprogramming process. However, unlike in mouse, OCT4 has not been replaced successfully during reprogramming of human cells. Here we report on a strategy to accomplish this replacement. Through a combination of transcriptome and bioinformatic analysis we have identified factors previously characterized as being lineage specifiers that are able to replace OCT4 and SOX2 in the reprogramming of human fibroblasts. Our results show that it is possible to replace OCT4 and SOX2 simultaneously with alternative lineage specifiers in the reprogramming of human cells. At a broader level, they also support a model in which counteracting lineage specification networks underlies the induction of pluripotency. © 2013 Elsevier Inc.

Research field(s)
Health Sciences, Biomedical Research, Developmental Biology

DOI
10.1016/j.stem.2013.06.019

Adding an unnatural covalent bond to proteins through proximity-enhanced bioreactivity

NOMIS Researcher(s)

Published in

September 1, 2013

Natural proteins often rely on the disulfide bond to covalently link side chains. Here we genetically introduce a new type of covalent bond into proteins by enabling an unnatural amino acid to react with a proximal cysteine. We demonstrate the utility of this bond for enabling irreversible binding between an affibody and its protein substrate, capturing peptide-protein interactions in mammalian cells, and improving the photon output of fluorescent proteins. © 2013 Nature America, Inc. All rights reserved.

Research field(s)
Health Sciences, Biomedical Research, Developmental Biology

DOI
10.1038/nmeth.2595

ZASC1 knockout mice exhibit an early bone marrow-specific defect in murine leukemia virus replication

NOMIS Researcher(s)

Published in

April 30, 2013

Background: ZASC1 is a zinc finger-containing transcription factor that was previously shown to bind to specific DNA binding sites in the Moloney murine leukemia virus (Mo-MuLV) promoter and is required for efficient viral mRNA transcription (J. Virol. 84:7473-7483, 2010). Methods. To determine whether this cellular factor influences Mo-MuLV replication and viral disease pathogenesis in vivo, we generated a ZASC1 knockout mouse model and completed both early infection and long term disease pathogenesis studies. Results: Mice lacking ZASC1 were born at the expected Mendelian ratio and showed no obvious physical or behavioral defects. Analysis of bone marrow samples revealed a specific increase in a common myeloid progenitor cell population in ZASC1-deficient mice, a result that is of considerable interest because osteoclasts derived from the myeloid lineage are among the first bone marrow cells infected by Mo-MuLV (J. Virol. 73: 1617-1623, 1999). Indeed, Mo-MuLV infection of neonatal mice revealed that ZASC1 is required for efficient early virus replication in the bone marrow, but not in the thymus or spleen. However, the absence of ZASC1 did not influence the timing of subsequent tumor progression or the types of tumors resulting from virus infection. Conclusions: These studies have revealed that ZASC1 is important for myeloid cell differentiation in the bone marrow compartment and that this cellular factor is required for efficient Mo-MuLV replication in this tissue at an early time point post-infection. © 2013 Seidel et al.; licensee BioMed Central Ltd.

Research field(s)
Health Sciences, Biomedical Research, Virology

DOI
10.1186/1743-422X-10-130

Reprogramming toward heart regeneration: Stem cells and beyond

NOMIS Researcher(s)

Published in

March 7, 2013

Finding a cure for cardiovascular disease remains a major unmet medical need. Recent investigations have started to unveil the mechanisms of mammalian heart regeneration. The study of the regenerative mechanisms in lower vertebrate and mammalian animal models has provided clues for the experimental activation of proregenerative responses in the heart. In parallel, the use of endogenous adult stem cell populations alongside the recent application of reprogramming technologies has created major expectations for the development of therapies targeting heart disease. Together, these new approaches are bringing us closer to more successful strategies for the treatment of heart disease. © 2013 Elsevier Inc.

Research field(s)
Health Sciences, Biomedical Research, Developmental Biology

DOI
10.1016/j.stem.2013.02.008

Directed Differentiation of Human Pluripotent Cells to Ureteric Bud Kidney Progenitor-Like Cells

NOMIS Researcher(s)

Published in

January 1, 2013

Diseases affecting the kidney constitute a major health issue worldwide. Their incidence and poor prognosis affirm the urgent need for the development of new therapeutic strategies. Recently, differentiation of pluripotent cells to somatic lineages has emerged as a promising approach for disease modelling and cell transplantation. Unfortunately, differentiation of pluripotent cells into renal lineages has demonstrated limited success. Here we report on the differentiation of human pluripotent cells into ureteric-bud-committed renal progenitor-like cells. The generated cells demonstrated rapid and specific expression of renal progenitor markers on 4-day exposure to defined media conditions. Further maturation into ureteric bud structures was accomplished on establishment of a three-dimensional culture system in which differentiated human cells assembled and integrated alongside murine cells for the formation of chimeric ureteric buds. Altogether, our results provide a new platform for the study of kidney diseases and lineage commitment, and open new avenues for the future application of regenerative strategies in the clinic. © 2013 Macmillan Publishers Limited. All rights reserved.

Research field(s)
Health Sciences, Biomedical Research, Developmental Biology

DOI
10.1038/ncb2872

TDP-43 loss of function inhibits endosomal trafficking and alters trophic signaling in neurons

NOMIS Researcher(s)

Published in

November 2, 2012

Nuclear clearance of TDP-43 into cytoplasmic aggregates is a key driver of neurodegeneration in amyotrophic lateral sclerosis (ALS) and frontotemporal lobar degeneration (FTLD), but the mechanisms are unclear. Here, we show that TDP-43 knockdown specifically reduces the number and motility of RAB11-positive recycling endosomes in dendrites, while TDP-43 overexpression has the opposite effect. This is associated with delayed transferrin recycling in TDP-43-knockdown neurons and decreased β2-transferrin levels in patient CSF. Whole proteome quantification identified the upregulation of the ESCRT component VPS4B upon TDP-43 knockdown in neurons. Luciferase reporter assays and chromatin immunoprecipitation suggest that TDP-43 represses VPS4B transcription. Preventing VPS4B upregulation or expression of its functional antagonist ALIX restores trafficking of recycling endosomes. Proteomic analysis revealed the broad reduction in surface expression of key receptors upon TDP-43 knockdown, including ErbB4, the neuregulin 1 receptor. TDP-43 knockdown delays the surface delivery of ErbB4. ErbB4 overexpression, but not neuregulin 1 stimulation, prevents dendrite loss upon TDP-43 knockdown. Thus, impaired recycling of ErbB4 and other receptors to the cell surface may contribute to TDP-43-induced neurodegeneration by blocking trophic signaling.

Research field(s)
Health Sciences, Biomedical Research, Developmental Biology

DOI
10.15252/embj.201694221

Identification of a 3-aminoimidazo[1,2-a]pyridine inhibitor of HIV-1 reverse transcriptase

NOMIS Researcher(s)

Published in

January 1, 2012

Background: Despite the effectiveness of highly active antiretroviral therapy (HAART), there remains an urgent need to develop new human immunodeficiency virus type 1 (HIV-1) inhibitors with better pharmacokinetic properties that are well tolerated, and that block common drug resistant virus strains. Methods: Here we screened an in-house small molecule library for novel inhibitors of HIV-1 replication. Results: An active compound containing a 3-aminoimidazo[1,2-a]pyridine scaffold was identified and quantitatively characterized as a non-nucleoside reverse transcriptase inhibitor (NNRTI). Conclusions: The potency of this compound coupled with its inexpensive chemical synthesis and tractability for downstream SAR analysis make this inhibitor a suitable lead candidate for further development as an antiviral drug.

Research field(s)
Health Sciences, Biomedical Research, Virology

DOI
10.1186/1743-422X-9-305

Differential requirements for clathrin endocytic pathway components in cellular entry by Ebola and Marburg glycoprotein pseudovirions

NOMIS Researcher(s)

Published in

October 10, 2011

Clathrin-mediated endocytosis was previously implicated as one of the cellular pathways involved in filoviral glycoprotein mediated viral entry into target cells. Here we have further dissected the requirements for different components of this pathway in Ebola versus Marburg virus glycoprotein (GP) mediated viral infection. Although a number of these components were involved in both cases; Ebola GP-dependent viral entry specifically required the cargo recognition proteins Eps15 and DAB2 as well as the clathrin adaptor protein AP-2. In contrast, Marburg GP-mediated infection was independent of these three proteins and instead required beta-arrestin 1 (ARRB1). These findings have revealed an unexpected difference between the clathrin pathway requirements for Ebola GP versus Marburg GP pseudovirion infection. Anthrax toxin also uses a clathrin-, and ARRB1-dependent pathway for cellular entry, indicating that the mechanism used by Marburg GP pseudovirions may be more generally important for pathogen entry. © 2011 Elsevier Inc.

Research field(s)
Health Sciences, Biomedical Research, Virology

DOI
10.1016/j.virol.2011.07.018

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