Eight induced pluripotent stem cell lines (iPSCs) derived from two patients with Leukocyte adhesion deficiency Type I (LAD I) with mutations in the ITGB2 gene.

Leukocyte Adhesion Deficiency Type I (LAD I) is a rare inborn error of immunity caused by mutations in the ITGB2 gene coding for β2-integrin CD18 on the surface of leukocytes. Affected patients display severe clinical manifestations with life threatening infections and inflammatory complications due to an impaired ability of leukocytes to transmigrate from the blood vessel to the tissue. Here we describe the generation of eight induced pluripotent stem cell lines from two patients with LAD I and mutations in the ITGB2 gene.

Role of PQBP1 in Pathogen Recognition-Impact on Innate Immunity.

The intrinsically disordered polyglutamine-binding protein 1 (PQBP1) has been linked to various cellular processes including transcription, alternative splicing, translation and innate immunity. Mutations in PQBP1 are causative for neurodevelopmental conditions collectively termed as the Renpenning syndrome spectrum. Intriguingly, cells of Renpenning syndrome patients exhibit a reduced innate immune response against human immunodeficiency virus 1 (HIV-1).

Regulation of STING activity in DNA sensing by ISG15 modification.

Sensing of human immunodeficiency virus type 1 (HIV-1) DNA is mediated by the cyclic GMP-AMP synthase-stimulator of interferon genes (cGAS-STING) signaling axis. Signal transduction and regulation of this cascade is achieved by post-translational modifications. Here we show that cGAS-STING-dependent HIV-1 sensing requires interferon-stimulated gene 15 (ISG15).

Gene editing of in macrophage-like cells reveals complex relationships between SAMHD1 phospho-regulation, HIV-1 restriction, and cellular dNTP levels.

We introduce BLaER1 cells as an alternative myeloid cell model in combination with CRISPR/Cas9-mediated gene editing to study the influence of sterile α motif and HD domain-containing protein 1 (SAMHD1) T592 phosphorylation on anti-viral restriction and the control of cellular dNTP levels in an endogenous, physiologically relevant context. A proper understanding of the mechanism of the anti-viral function of SAMHD1 will provide attractive strategies aiming at selectively manipulating SAMHD1 without affecting other cellular functions. Even more, our toolkit may inspire further genetic analysis and investigation of restriction factors inhibiting retroviruses and their cellular function and regulation, leading to a deeper understanding of intrinsic anti-viral immunity.

Recognition of HIV-1 capsid by PQBP1 licenses an innate immune sensing of nascent HIV-1 DNA.

We have previously described polyglutamine-binding protein 1 (PQBP1) as an adapter required for the cyclic GMP-AMP synthase (cGAS)-mediated innate response to the human immunodeficiency virus 1 (HIV-1) and other lentiviruses. Cytoplasmic HIV-1 DNA is a transient and low-abundance pathogen-associated molecular pattern (PAMP), and the mechanism for its detection and verification is not fully understood. Here, we show a two-factor authentication strategy by the innate surveillance machinery to selectively respond to the low concentration of HIV-1 DNA, while distinguishing these species from extranuclear DNA molecules.

Generation of three induced pluripotent cell lines (iPSCs) from an Aicardi-Goutières syndrome (AGS) patient harboring a deletion in the genomic locus of the sterile alpha motif and HD domain containing protein 1 (SAMHD1).

Aicardi-Goutières syndrome (AGS) is a hereditary early onset encephalopathy. AGS patients display variable clinical manifestations including intracranial calcification, cerebral atrophy, white matter abnormalities and characteristic leukocytosis as well as a constitutive upregulation of type I IFN production indicative of a type I interferonopathy. Seven genes (SAMHD1, TREX1, RNASEH2B, RNASEH2C, RNASEH2A, ADAR1, IFIH1) have been associated with the AGS phenotype, up to now.

Induced pluripotent stem cell line (PEIi003-A) derived from an apparently healthy male individual.

Induced pluripotent stem cells (iPSCs) are a useful tool to investigate pathomechanistic and cellular processes due to their differentiation potential into different somatic cell types in vitro. Here, we have generated iPSCs from an apparently healthy male individual using an integration-free reprogramming method. The resulting iPSCs are pluripotent and display a normal karyotype.

Induced pluripotent stem cells (iPSCs) derived from a renpenning syndrome patient with c.459_462delAGAG mutation in PQBP1 (PEIi001-A).

The Renpenning syndrome spectrum is a rare X-linked mental retardation syndrome characterized by intellectual disability, microcephaly, low stature, lean body and hypogonadism. Mutations in the polyglutamine tract binding protein 1 (PQBP1) locus are causative for disease. Here, we describe the generation of an iPSC line from a patient mutated in the polar amino acid-rich domain of PQBP1 resulting in a C-terminal truncated protein (c.

The impact of transposable element activity on therapeutically relevant human stem cells.

Human stem cells harbor significant potential for basic and clinical translational research as well as regenerative medicine. Currently ~ 3000 adult and ~ 30 pluripotent stem cell-based, interventional clinical trials are ongoing worldwide, and numbers are increasing continuously. Although stem cells are promising cell sources to treat a wide range of human diseases, there are also concerns regarding potential risks associated with their clinical use, including genomic instability and tumorigenesis concerns.

Dephosphorylation of the HIV-1 restriction factor SAMHD1 is mediated by PP2A-B55α holoenzymes during mitotic exit.

SAMHD1 is a critical restriction factor for HIV-1 in non-cycling cells and its antiviral activity is regulated by T592 phosphorylation. Here, we show that SAMHD1 dephosphorylation at T592 is controlled during the cell cycle, occurring during M/G transition in proliferating cells. Using several complementary proteomics and biochemical approaches, we identify the phosphatase PP2A-B55α responsible for rendering SAMHD1 antivirally active.

Interferons Induce Expression of SAMHD1 in Monocytes through Down-regulation of miR-181a and miR-30a.

SAMHD1 is a phosphohydrolase maintaining cellular dNTP homeostasis but also acts as a critical regulator in innate immune responses due to its antiviral activity and association with autoimmune disease, leading to aberrant activation of interferon. SAMHD1 expression is differentially regulated by interferon in certain primary cells, but the underlying mechanism is not understood. Here, we report a detailed characterization of the promotor region, the 5'- and 3'-untranslated region (UTR) of SAMHD1, and the mechanism responsible for the cell type-dependent up-regulation of SAMHD1 protein by interferon.

Reprogramming triggers endogenous L1 and Alu retrotransposition in human induced pluripotent stem cells.

Human induced pluripotent stem cells (hiPSCs) are capable of unlimited proliferation and can differentiate in vitro to generate derivatives of the three primary germ layers. Genetic and epigenetic abnormalities have been reported by Wissing and colleagues to occur during hiPSC derivation, including mobilization of engineered LINE-1 (L1) retrotransposons. However, incidence and functional impact of endogenous retrotransposition in hiPSCs are yet to be established.

Primate-specific endogenous retrovirus-driven transcription defines naive-like stem cells.

Naive embryonic stem cells hold great promise for research and therapeutics as they have broad and robust developmental potential. While such cells are readily derived from mouse blastocysts it has not been possible to isolate human equivalents easily, although human naive-like cells have been artificially generated (rather than extracted) by coercion of human primed embryonic stem cells by modifying culture conditions or through transgenic modification. Here we show that a sub-population within cultures of human embryonic stem cells (hESCs) and induced pluripotent stem cells (hiPSCs) manifests key properties of naive state cells.

Gibbon genome and the fast karyotype evolution of small apes.

Gibbons are small arboreal apes that display an accelerated rate of evolutionary chromosomal rearrangement and occupy a key node in the primate phylogeny between Old World monkeys and great apes. Here we present the assembly and analysis of a northern white-cheeked gibbon (Nomascus leucogenys) genome. We describe the propensity for a gibbon-specific retrotransposon (LAVA) to insert into chromosome segregation genes and alter transcription by providing a premature termination site, suggesting a possible molecular mechanism for the genome plasticity of the gibbon lineage.

Human endogenous retrovirus K (HML-2) RNA and protein expression is a marker for human embryonic and induced pluripotent stem cells.

Background: Malignant human embryonal carcinoma cells (ECCs) rely on similar transcriptional networks as non-malignant embryonic stem cells (ESCs) to control selfrenewal, maintain pluripotency, and inhibit differentiation. Because re-activation of silenced HERV-K(HML-2) loci is a hallmark of ECCs, we asked if this HERV group was also reactivated in ESCs and induced pluripotent stem cells (iPSCs).

Findings: Using RT-PCR and Western Blot, we demonstrate HERV-K(HML-2) RNA and protein expression in undifferentiated human ESCs and iPSCs.

Biochemical analysis of the complex between the tetrameric export adapter protein Rec of HERV-K/HML-2 and the responsive RNA element RcRE pck30.

The RNA export adaptor protein Rec, encoded for by the human endogenous retrovirus HERV-K/HML-2 elements, binds to the Rec responsive element (RcRE) located in the 3' untranslated region of HERV-K/HML-2 transcripts. Binding allows the nucleocytoplasmic export of unspliced viral RNA, thereby overcoming host restriction. Chemical probing of the secondary structure of the RcRE corroborated the theory that the RcRE forms a complex folded structure with seven stem-loop regions.

Expression of the human endogenous retrovirus (HERV) group HML-2/HERV-K does not depend on canonical promoter elements but is regulated by transcription factors Sp1 and Sp3.

After fixation in the human genome, human endogenous retroviruses (HERVs) are bona fide cellular genes despite their exogenous origin. To be able to spread within the germ line and the early embryo, the ancient retroviral promoters must have adapted to the requirements for expression in these cell types. We describe that in contrast to the case for current exogenous retroviruses, which replicate in specific somatic cells, the long terminal repeat (LTR) of the human endogenous retrovirus HERV-K acts as a TATA- and initiator element-independent promoter with a variable transcription start site.