Progress and harmonization of gene editing to treat human diseases: Proceeding of COST Action CA21113 GenE-HumDi

The European Cooperation in Science and Technology (COST) is an intergovernmental organization dedicated to funding and coordinating scientific and technological research in Europe, fostering collaboration among researchers and institutions across countries. Recently, COST Action funded the "Genome Editing to treat Human Diseases" (GenE-HumDi) network, uniting various stakeholders such as pharmaceutical companies, academic institutions, regulatory agencies, biotech firms, and patient advocacy groups. GenE-HumDi's primary objective is to expedite the application of genome editing for therapeutic purposes in treating human diseases. To achieve this goal, GenE-HumDi is organized in several working groups, each focusing on specific aspects. These groups aim to enhance genome editing technologies, assess delivery systems, address safety concerns, promote clinical translation, and develop regulatory guidelines. The network seeks to establish standard procedures and guidelines for these areas to standardize scientific practices and facilitate knowledge sharing. Furthermore, GenE-HumDi aims to communicate its findings to the public in accessible yet rigorous language, emphasizing genome editing's potential to revolutionize the treatment of many human diseases. The inaugural GenE-HumDi meeting, held in Granada, Spain, in March 2023, featured presentations from experts in the field, discussing recent breakthroughs in delivery methods, safety measures, clinical translation, and regulatory aspects related to gene editing.

Negative DNA supercoiling induces genome-wide Cas9 off-target activity

CRISPR-Cas9 is a powerful gene-editing technology; however, off-target activity remains an important consideration for therapeutic applications. We have previously shown that force-stretching DNA induces off-target activity and hypothesized that distortions of the DNA topology in vivo, such as negative DNA supercoiling, could reduce Cas9 specificity. Using single-molecule optical-tweezers, we demonstrate that negative supercoiling λ-DNA induces sequence-specific Cas9 off-target binding at multiple sites, even at low forces. Using an adapted CIRCLE-seq approach, we detect over 10,000 negative-supercoiling-induced Cas9 off-target double-strand breaks genome-wide caused by increased mismatch tolerance. We further demonstrate in vivo that directed local DNA distortion increases off-target activity in cells and that induced off-target events can be detected during Cas9 genome editing. These data demonstrate that Cas9 off-target activity is regulated by DNA topology in vitro and in vivo, suggesting that cellular processes, such as transcription and replication, could induce off-target activity at previously overlooked sites.

Elevated Adipocyte Membrane Phospholipid Saturation Does Not Compromise Insulin Signaling

Increased saturated fatty acid (SFA) levels in membrane phospholipids have been implicated in the development of metabolic disease. Here, we tested the hypothesis that increased SFA content in cell membranes negatively impacts adipocyte insulin signaling. Preadipocyte cell models with elevated SFA levels in phospholipids were generated by disrupting the ADIPOR2 locus, which resulted in a striking twofold increase in SFA-containing phosphatidylcholines and phosphatidylethanolamines, which persisted in differentiated adipocytes. Similar changes in phospholipid composition were observed in white adipose tissues isolated from the ADIPOR2-knockout mice. The SFA levels in phospholipids could be further increased by treating ADIPOR2-deficient cells with palmitic acid and resulted in reduced membrane fluidity and endoplasmic reticulum stress in mouse and human preadipocytes. Strikingly, increased SFA levels in differentiated adipocyte phospholipids had no effect on adipocyte gene expression or insulin signaling in vitro. Similarly, increased adipocyte phospholipid saturation did not impair white adipose tissue function in vivo, even in mice fed a high-saturated fat diet at thermoneutrality. We conclude that increasing SFA levels in adipocyte phospholipids is well tolerated and does not affect adipocyte insulin signaling in vitro and in vivo.

A Type II-B Cas9 nuclease with minimized off-targets and reduced chromosomal translocations in vivo

Streptococcus pyogenes Cas9 (SpCas9) and derived enzymes are widely used as genome editors, but their promiscuous nuclease activity often induces undesired mutations and chromosomal rearrangements. Several strategies for mapping off-target effects have emerged, but they suffer from limited sensitivity. To increase the detection sensitivity, we develop an off-target assessment workflow that uses Duplex Sequencing. The strategy increases sensitivity by one order of magnitude, identifying previously unknown SpCas9's off-target mutations in the humanized PCSK9 mouse model. To reduce off-target risks, we perform a bioinformatic search and identify a high-fidelity Cas9 variant of the II-B subfamily from Parasutterella secunda (PsCas9). PsCas9 shows improved specificity as compared to SpCas9 across multiple tested sites, both in vitro and in vivo, including the PCSK9 site. In the future, while PsCas9 will offer an alternative to SpCas9 for research and clinical use, the Duplex Sequencing workflow will enable a more sensitive assessment of Cas9 editing outcomes.

Simultaneous inhibition of DNA-PK and Polϴ improves integration efficiency and precision of genome editing

Genome editing, specifically CRISPR/Cas9 technology, has revolutionized biomedical research and offers potential cures for genetic diseases. Despite rapid progress, low efficiency of targeted DNA integration and generation of unintended mutations represent major limitations for genome editing applications caused by the interplay with DNA double-strand break repair pathways. To address this, we conduct a large-scale compound library screen to identify targets for enhancing targeted genome insertions. Our study reveals DNA-dependent protein kinase (DNA-PK) as the most effective target to improve CRISPR/Cas9-mediated insertions, confirming previous findings. We extensively characterize AZD7648, a selective DNA-PK inhibitor, and find it to significantly enhance precise gene editing. We further improve integration efficiency and precision by inhibiting DNA polymerase theta (Polϴ). The combined treatment, named 2iHDR, boosts templated insertions to 80% efficiency with minimal unintended insertions and deletions. Notably, 2iHDR also reduces off-target effects of Cas9, greatly enhancing the fidelity and performance of CRISPR/Cas9 gene editing.

TLCD1 and TLCD2 regulate cellular phosphatidylethanolamine composition and promote the progression of non-alcoholic steatohepatitis

The fatty acid composition of phosphatidylethanolamine (PE) determines cellular metabolism, oxidative stress, and inflammation. However, our understanding of how cells regulate PE composition is limited. Here, we identify a genetic locus on mouse chromosome 11, containing two poorly characterized genes Tlcd1 and Tlcd2, that strongly influences PE composition. We generated Tlcd1/2 double-knockout (DKO) mice and found that they have reduced levels of hepatic monounsaturated fatty acid (MUFA)-containing PE species. Mechanistically, TLCD1/2 proteins act cell intrinsically to promote the incorporation of MUFAs into PEs. Furthermore, TLCD1/2 interact with the mitochondria in an evolutionarily conserved manner and regulate mitochondrial PE composition. Lastly, we demonstrate the biological relevance of our findings in dietary models of metabolic disease, where Tlcd1/2 DKO mice display attenuated development of non-alcoholic steatohepatitis compared to controls. Overall, we identify TLCD1/2 proteins as key regulators of cellular PE composition, with our findings having broad implications in understanding and treating disease.

The regulation of cellular phosphatidylethanolamine (PE) acyl chain composition is poorly understood. Here, the authors show that TLCD1 and TLCD2 proteins mediate the formation of monounsaturated fatty acid-containing PE species and promote the progression of non-alcoholic steatohepatitis.

Harnessing DSB repair to promote efficient homology-dependent and -independent prime editing

Prime editing recently emerged as a next-generation approach for precise genome editing. Here we exploit DNA double-strand break (DSB) repair to develop two strategies that install precise genomic insertions using an SpCas9 nuclease-based prime editor (PEn). We first demonstrate that PEn coupled to a regular prime editing guide RNA (pegRNA) efficiently promotes short genomic insertions through a homology-dependent DSB repair mechanism. While PEn editing leads to increased levels of by-products, it can rescue pegRNAs that perform poorly with a nickase-based prime editor. We also present a small molecule approach that yields increased product purity of PEn editing. Next, we develop a homology-independent PEn editing strategy, which installs genomic insertions at DSBs through the non-homologous end joining pathway (NHEJ). Lastly, we show that PEn-mediated insertions at DSBs prevent Cas9-induced large chromosomal deletions and provide evidence that continuous Cas9-mediated cutting is one of the mechanisms by which Cas9-induced large deletions arise. Altogether, this work expands the current prime editing toolbox by leveraging distinct DNA repair mechanisms including NHEJ, which represents the primary pathway of DSB repair in mammalian cells.

Prime editing is a next-generation approach for precision genome engineering. Here the authors design a nuclease-based prime editor that leverages DNA repair pathways for targeted genomic insertions.

Correction of a urea cycle defect after ex vivo gene editing of human hepatocytes

Ornithine transcarbamylase deficiency (OTCD) is a monogenic disease of ammonia metabolism in hepatocytes. Severe disease is frequently treated by orthotopic liver transplantation. An attractive approach is the correction of a patient’s own cells to regenerate the liver with gene-repaired hepatocytes. This study investigates the efficacy and safety of ex vivo correction of primary human hepatocytes. Hepatocytes isolated from an OTCD patient were genetically corrected ex vivo, through the deletion of a mutant intronic splicing site achieving editing efficiencies >60% and the restoration of the urea cycle in vitro. The corrected hepatocytes were transplanted into the liver of FRGN mice and repopulated to high levels (>80%). Animals transplanted and liver repopulated with genetically edited patient hepatocytes displayed normal ammonia, enhanced clearance of an ammonia challenge and OTC enzyme activity, as well as lower urinary orotic acid when compared to mice repopulated with unedited patient hepatocytes. Gene expression was shown to be similar between mice transplanted with unedited or edited patient hepatocytes. Finally, a genome-wide screening by performing CIRCLE-seq and deep sequencing of >70 potential off-targets revealed no unspecific editing. Overall analysis of disease phenotype, gene expression, and possible off-target editing indicated that the gene editing of a severe genetic liver disease was safe and effective.

Universal toxin-based selection for precise genome engineering in human cells

Prokaryotic restriction enzymes, recombinases and Cas proteins are powerful DNA engineering and genome editing tools. However, in many primary cell types, the efficiency of genome editing remains low, impeding the development of gene- and cell-based therapeutic applications. A safe strategy for robust and efficient enrichment of precisely genetically engineered cells is urgently required. Here, we screen for mutations in the receptor for Diphtheria Toxin (DT) which protect human cells from DT. Selection for cells with an edited DT receptor variant enriches for simultaneously introduced, precisely targeted gene modifications at a second independent locus, such as nucleotide substitutions and DNA insertions. Our method enables the rapid generation of a homogenous cell population with bi-allelic integration of a DNA cassette at the selection locus, without clonal isolation. Toxin-based selection works in both cancer-transformed and non-transformed cells, including human induced pluripotent stem cells and human primary T-lymphocytes, as well as it is applicable also in vivo, in mice with humanized liver. This work represents a flexible, precise, and efficient selection strategy to engineer cells using CRISPR-Cas and base editing systems.

Extensive transcription mis-regulation and membrane defects in AdipoR2-deficient cells challenged with saturated fatty acids

How cells maintain vital membrane lipid homeostasis while obtaining most of their constituent fatty acids from a varied diet remains largely unknown. Here, we used transcriptomics, lipidomics, growth and respiration assays, and membrane property analyses in human HEK293 cells or human umbilical vein endothelial cells (HUVEC) to show that the function of AdipoR2 is to respond to membrane rigidification by regulating many lipid metabolism genes. We also show that AdipoR2-dependent membrane homeostasis is critical for growth and respiration in cells challenged with saturated fatty acids. Additionally, we found that AdipoR2 deficiency causes transcriptome and cell physiological defects similar to those observed in SREBP-deficient cells upon SFA challenge. Finally, we compared several genes considered important for lipid homeostasis, namely AdipoR2, SCD, FADS2, PEMT and ACSL4, and found that AdipoR2 and SCD are the most important among these to prevent membrane rigidification and excess saturation when human cells are challenged with exogenous SFAs. We conclude that AdipoR2-dependent membrane homeostasis is one of the primary mechanisms that protects against exogenous SFAs.

Development of an ObLiGaRe Doxycycline Inducible Cas9 system for pre-clinical cancer drug discovery

The CRISPR-Cas9 system has increased the speed and precision of genetic editing in cells and animals. However, model generation for drug development is still expensive and time-consuming, demanding more target flexibility and faster turnaround times with high reproducibility. The generation of a tightly controlled ObLiGaRe doxycycline inducible SpCas9 (ODInCas9) transgene and its use in targeted ObLiGaRe results in functional integration into both human and mouse cells culminating in the generation of the ODInCas9 mouse. Genomic editing can be performed in cells of various tissue origins without any detectable gene editing in the absence of doxycycline. Somatic in vivo editing can model non-small cell lung cancer (NSCLC) adenocarcinomas, enabling treatment studies to validate the efficacy of candidate drugs. The ODInCas9 mouse allows robust and tunable genome editing granting flexibility, speed and uniformity at less cost, leading to high throughput and practical preclinical in vivo therapeutic testing.

Axl receptor tyrosine kinase is a regulator of apolipoprotein E

Alzheimer's disease (AD), the leading cause of dementia, is a chronic neurodegenerative disease. Apolipoprotein E (apoE), which carries lipids in the brain in the form of lipoproteins, plays an undisputed role in AD pathophysiology. A high-throughput phenotypic screen was conducted using a CCF-STTG1 human astrocytoma cell line to identify small molecules that could upregulate apoE secretion. AZ7235, a previously discovered Axl kinase inhibitor, was identified to have robust apoE activity in brain microglia, astrocytes and pericytes. AZ7235 also increased expression of ATP-binding cassette protein A1 (ABCA1), which is involved in the lipidation and secretion of apoE. Moreover, AZ7235 did not exhibit Liver-X-Receptor (LXR) activity and stimulated apoE and ABCA1 expression in the absence of LXR. Target validation studies using AXL-/- CCF-STTG1 cells showed that Axl is required to mediate AZ7235 upregulation of apoE and ABCA1. Intriguingly, apoE expression and secretion was significantly attenuated in AXL-deficient CCF-STTG1 cells and reconstitution of Axl or kinase-dead Axl significantly restored apoE baseline levels, demonstrating that Axl also plays a role in maintaining apoE homeostasis in astrocytes independent of its kinase activity. Lastly, these effects may require human apoE regulatory sequences, as AZ7235 exhibited little stimulatory activity toward apoE and ABCA1 in primary murine glia derived from neonatal human APOE3 targeted-replacement mice. Collectively, we identified a small molecule that exhibits robust apoE and ABCA1 activity independent of the LXR pathway in human cells and elucidated a novel relationship between Axl and apoE homeostasis in human astrocytes.

Unbiased detection of CRISPR off-targets in vivo using DISCOVER-Seq

CRISPR-Cas genome editing induces targeted DNA damage but can also affect off-target sites. Current off-target discovery methods work using purified DNA or specific cellular models but are incapable of direct detection in vivo. We developed DISCOVER-Seq (discovery of in situ Cas off-targets and verification by sequencing), a universally applicable approach for unbiased off-target identification that leverages the recruitment of DNA repair factors in cells and organisms. Tracking the precise recruitment of MRE11 uncovers the molecular nature of Cas activity in cells with single-base resolution. DISCOVER-Seq works with multiple guide RNA formats and types of Cas enzymes, allowing characterization of new editing tools. Off-targets can be identified in cell lines and patient-derived induced pluripotent stem cells and during adenoviral editing of mice, paving the way for in situ off-target discovery within individual patient genotypes during therapeutic genome editing.

In vivo genome and base editing of a human PCSK9 knock-in hypercholesterolemic mouse model

Background

Plasma concentration of low-density lipoprotein (LDL) cholesterol is a well-established risk factor for cardiovascular disease. Inhibition of proprotein convertase subtilisin/kexin type 9 (PCSK9), which regulates cholesterol homeostasis, has recently emerged as an approach to reduce cholesterol levels. The development of humanized animal models is an important step to validate and study human drug targets, and use of genome and base editing has been proposed as a mean to target disease alleles.

Results

To address the lack of validated models to test the safety and efficacy of techniques to target human PCSK9, we generated a liver-specific human PCSK9 knock-in mouse model (hPCSK9-KI). We showed that plasma concentrations of total cholesterol were higher in hPCSK9-KI than in wildtype mice and increased with age. Treatment with evolocumab, a monoclonal antibody that targets human PCSK9, reduced cholesterol levels in hPCSK9-KI but not in wildtype mice, showing that the hypercholesterolemic phenotype was driven by overexpression of human PCSK9. CRISPR-Cas9-mediated genome editing of human PCSK9 reduced plasma levels of human and not mouse PCSK9, and in parallel reduced plasma concentrations of total cholesterol; genome editing of mouse Pcsk9 did not reduce cholesterol levels. Base editing using a guide RNA that targeted human and mouse PCSK9 reduced plasma levels of human and mouse PCSK9 and total cholesterol. In our mouse model, base editing was more precise than genome editing, and no off-target editing nor chromosomal translocations were identified.

Conclusions

Here, we describe a humanized mouse model with liver-specific expression of human PCSK9 and a human-like hypercholesterolemia phenotype, and demonstrate that this mouse can be used to evaluate antibody and gene editing-based (genome and base editing) therapies to modulate the expression of human PCSK9 and reduce cholesterol levels. We predict that this mouse model will be used in the future to understand the efficacy and safety of novel therapeutic approaches for hypercholesterolemia.

Electronic supplementary material

The online version of this article (10.1186/s12915-018-0624-2) contains supplementary material, which is available to authorized users.

In vivo genome and base editing of a human PCSK9 knock-in hypercholesterolemic mouse model

BACKGROUND

Plasma concentration of low-density lipoprotein (LDL) cholesterol is a well-established risk factor for cardiovascular disease. Inhibition of proprotein convertase subtilisin/kexin type 9 (PCSK9), which regulates cholesterol homeostasis, has recently emerged as an approach to reduce cholesterol levels. The development of humanized animal models is an important step to validate and study human drug targets, and use of genome and base editing has been proposed as a mean to target disease alleles.

RESULTS

To address the lack of validated models to test the safety and efficacy of techniques to target human PCSK9, we generated a liver-specific human PCSK9 knock-in mouse model (hPCSK9-KI). We showed that plasma concentrations of total cholesterol were higher in hPCSK9-KI than in wildtype mice and increased with age. Treatment with evolocumab, a monoclonal antibody that targets human PCSK9, reduced cholesterol levels in hPCSK9-KI but not in wildtype mice, showing that the hypercholesterolemic phenotype was driven by overexpression of human PCSK9. CRISPR-Cas9-mediated genome editing of human PCSK9 reduced plasma levels of human and not mouse PCSK9, and in parallel reduced plasma concentrations of total cholesterol; genome editing of mouse Pcsk9 did not reduce cholesterol levels. Base editing using a guide RNA that targeted human and mouse PCSK9 reduced plasma levels of human and mouse PCSK9 and total cholesterol. In our mouse model, base editing was more precise than genome editing, and no off-target editing nor chromosomal translocations were identified.

CONCLUSIONS

Here, we describe a humanized mouse model with liver-specific expression of human PCSK9 and a human-like hypercholesterolemia phenotype, and demonstrate that this mouse can be used to evaluate antibody and gene editing-based (genome and base editing) therapies to modulate the expression of human PCSK9 and reduce cholesterol levels. We predict that this mouse model will be used in the future to understand the efficacy and safety of novel therapeutic approaches for hypercholesterolemia.

BE-FLARE: a fluorescent reporter of base editing activity reveals editing characteristics of APOBEC3A and APOBEC3B

BACKGROUND

Base Editing is a precise genome editing method that uses a deaminase-Cas9 fusion protein to mutate cytidine to thymidine in target DNA in situ without the generation of a double-strand break. However, the efficient enrichment of genetically modified cells using this technique is limited by the ability to detect such events.

RESULTS

We have developed a Base Editing FLuorescent Activity REporter (BE-FLARE), which allows for the enrichment of cells that have undergone editing of target loci based on a fluorescence shift from BFP to GFP. We used BE-FLARE to evaluate the editing efficiency of APOBEC3A and APOBEC3B family members as alternatives deaminase domains to the rat APOBEC1 domain used in base editor 3 (BE3). We identified human APOBEC3A and APOBEC3B as highly efficient cytidine deaminases for base editing applications with unique properties.

CONCLUSIONS

Using BE-FLARE to report on the efficiency and precision of editing events, we outline workflows for the accelerated generation of genetically engineered cell models and the discovery of alternative base editors.

Functional Gut Microbiota Remodeling Contributes to the Caloric Restriction-Induced Metabolic Improvements

Caloric restriction (CR) stimulates development of functional beige fat and extends healthy lifespan. Here we show that compositional and functional changes in the gut microbiota contribute to a number of CR-induced metabolic improvements and promote fat browning. Mechanistically, these effects are linked to a lower expression of the key bacterial enzymes necessary for the lipid A biosynthesis, a critical lipopolysaccharide (LPS) building component. The decreased LPS dictates the tone of the innate immune response during CR, leading to increased eosinophil infiltration and anti-inflammatory macrophage polarization in fat of the CR animals. Genetic and pharmacological suppression of the LPS-TLR4 pathway or transplantation with Tlr4^-/- bone-marrow-derived hematopoietic cells increases beige fat development and ameliorates diet-induced fatty liver, while Tlr4^-/- or microbiota-depleted mice are resistant to further CR-stimulated metabolic alterations. These data reveal signals critical for our understanding of the microbiota-fat signaling axis during CR and provide potential new anti-obesity therapeutics.

Decoding non-random mutational signatures at Cas9 targeted sites

The mutation patterns at Cas9 targeted sites contain unique information regarding the nuclease activity and repair mechanisms in mammalian cells. However, analytical framework for extracting such information are lacking. Here, we present a novel computational platform called Rational InDel Meta-Analysis (RIMA) that enables an in-depth comprehensive analysis of Cas9-induced genetic alterations, especially InDels mutations. RIMA can be used to quantitate the contribution of classical microhomology-mediated end joining (c-MMEJ) pathway in the formation of mutations at Cas9 target sites. We used RIMA to compare mutational signatures at 15 independent Cas9 target sites in human A549 wildtype and A549-POLQ knockout cells to elucidate the role of DNA polymerase θ in c-MMEJ. Moreover, the single nucleotide insertions at the Cas9 target sites represent duplications of preceding nucleotides, suggesting that the flexibility of the Cas9 nuclease domains results in both blunt- and staggered-end cuts. Thymine at the fourth nucleotide before protospacer adjacent motif (PAM) results in a two-fold higher occurrence of single nucleotide InDels compared to guanine at the same position. This study provides a novel approach for the characterization of the Cas9 nucleases with improved accuracy in predicting genome editing outcomes and a potential strategy for homology-independent targeted genomic integration.

Clusterin Is Required for β-Amyloid Toxicity in Human iPSC-Derived Neurons

Our understanding of the molecular processes underlying Alzheimer's disease (AD) is still limited, hindering the development of effective treatments, and highlighting the need for human-specific models. Advances in identifying components of the amyloid cascade are progressing, including the role of the protein clusterin in mediating β-amyloid (Aβ) toxicity. Mutations in the clusterin gene (CLU), a major genetic AD risk factor, are known to have important roles in Aβ processing. Here we investigate how CLU mediates Aβ-driven neurodegeneration in human induced pluripotent stem cell (iPSC)-derived neurons. We generated a novel CLU-knockout iPSC line by CRISPR/Cas9-mediated gene editing to investigate Aβ-mediated neurodegeneration in cortical neurons differentiated from wild type and CLU knockout iPSCs. We measured response to Aβ using an imaging assay and measured changes in gene expression using qPCR and RNA sequencing. In wild type neurons imaging indicated that neuronal processes degenerate following treatment with Aβ_25-35 peptides and Aβ_1-42 oligomers, in a dose dependent manner, and that intracellular levels of clusterin are increased following Aβ treatment. However, in CLU knockout neurons Aβ exposure did not affect neurite length, suggesting that clusterin is an important component of the amyloid cascade. Transcriptomic data were analyzed to elucidate the pathways responsible for the altered response to Aβ in neurons with the CLU deletion. Four of the five genes previously identified as downstream to Aβ and Dickkopf-1 (DKK1) proteins in an Aβ-driven neurotoxic pathway in rodent cells were also dysregulated in human neurons with the CLU deletion. AD and lysosome pathways were the most significantly dysregulated pathways in the CLU knockout neurons, and pathways relating to cytoskeletal processes were most dysregulated in Aβ treated neurons. The absence of neurodegeneration in the CLU knockout neurons in response to Aβ compared to the wild type neurons supports the role of clusterin in Aβ-mediated AD pathogenesis.

NKX6.1 induced pluripotent stem cell reporter lines for isolation and analysis of functionally relevant neuronal and pancreas populations

Recent studies have reported significant advances in the differentiation of human pluripotent stem cells to clinically relevant cell types such as the insulin producing beta-like cells and motor neurons. However, many of the current differentiation protocols lead to heterogeneous cell cultures containing cell types other than the targeted cell fate. Genetically modified human pluripotent stem cells reporting the expression of specific genes are of great value for differentiation protocol optimization and for the purification of relevant cell populations from heterogeneous cell cultures. Here we present the generation of human induced pluripotent stem cell (iPSC) lines with a GFP reporter inserted in the endogenous NKX6.1 locus. Characterization of the reporter lines demonstrated faithful GFP labelling of NKX6.1 expression during pancreas and motor neuron differentiation. Cell sorting and gene expression profiling by RNA sequencing revealed that NKX6.1-positive cells from pancreatic differentiations closely resemble human beta cells. Furthermore, functional characterization of the isolated cells demonstrated that glucose-stimulated insulin secretion is mainly confined to the NKX6.1-positive cells. We expect that the NKX6.1-GFP iPSC lines and the results presented here will contribute to the further refinement of differentiation protocols and characterization of hPSC-derived beta cells and motor neurons for disease modelling and cell replacement therapies.

Functional significance of co-occurring mutations in PIK3CA and MAP3K1 in breast cancer

The PI3Kα signaling pathway is frequently hyper-activated in breast cancer (BrCa), as a result of mutations/amplifications in oncogenes (e.g. HER2), decreased function in tumor suppressors (e.g. PTEN) or activating mutations in key components of the pathway. In particular, activating mutations of PIK3CA (~45%) are frequently found in luminal A BrCa samples. Genomic studies have uncovered inactivating mutations in MAP3K1 (13-20%) and MAP2K4 (~8%), two upstream kinases of the JNK apoptotic pathway in luminal A BrCa samples. Further, simultaneous mutation of PIK3CA and MAP3K1 are found in ~11% of mutant PIK3CA tumors. How these two alterations may cooperate to elicit tumorigenesis and impact the sensitivity to PI3K and AKT inhibitors is currently unknown. Using CRISPR gene editing we have genetically disrupted MAP3K1 expression in mutant PIK3CA cell lines to specifically create in vitro models reflecting the mutational status of PIK3CA and MAP3K1 in BrCa patients. MAP3K1 deficient cell lines exhibited ~2.4-fold increased proliferation rate and decreased sensitivity to PI3Kα/δ(AZD8835) and AKT (AZD5363) inhibitors (~2.61 and ~5.23-fold IC₅₀ increases, respectively) compared with parental control cell lines. In addition, mechanistic analysis revealed that MAP3K1 disruption enhances AKT phosphorylation and downstream signaling and reduces sensitivity to AZD5363-mediated pathway inhibition. This appears to be a consequence of deficient MAP3K1-JNK signaling increasing IRS1 stability and therefore promoting IRS1 binding to p85, resulting in enhanced PI3Kα activity. Using 3D-MCF10A-PI3Kα^H1047R models, we found that MAP3K1 depletion increased overall acinar volume and counteracted AZD5363-mediated reduction of acinar growth due to enhanced proliferation and reduced apoptosis. Furthermore, in vivo efficacy studies revealed that MAP3K1-deficient MCF7 tumors were less sensitive to AKT inhibitor treatment, compared with parental MCF7 tumors. Our study provides mechanistic and in vivo evidence indicating a role for MAP3K1 as a tumor suppressor gene at least in the context of PIK3CA-mutant backgrounds. Further, our work predicts that MAP3K1 mutational status may be considered as a predictive biomarker for efficacy in PI3K pathway inhibitor trials.

Small molecule inducers of ABCA1 and apoE that act through indirect activation of the LXR pathway

apoE is the primary lipid carrier within the CNS and the strongest genetic risk factor for late onset Alzheimer's disease (AD). apoE is primarily lipidated via ABCA1, and both are under transcriptional regulation by the nuclear liver X receptor (LXR). Considerable evidence from genetic (using ABCA1 overexpression) and pharmacological (using synthetic LXR agonists) studies in AD mouse models suggests that increased levels of lipidated apoE can improve cognitive performance and, in some strains, can reduce amyloid burden. However, direct synthetic LXR ligands have hepatotoxic side effects that limit their clinical use. Here, we describe a set of small molecules, previously annotated as antagonists of the purinergic receptor, P2X7, which enhance ABCA1 expression and activity as well as apoE secretion, and are not direct LXR ligands. Furthermore, P2X7 is not required for these molecules to induce ABCA1 upregulation and apoE secretion, demonstrating that the ABCA1 and apoE effects are mechanistically independent of P2X7 inhibition. Hence, we have identified novel dual activity compounds that upregulate ABCA1 across multiple CNS cell types, including human astrocytes, pericytes, and microglia, through an indirect LXR mechanism and that also independently inhibit P2X7 receptor activity.

Therapeutic Genome Editing With CRISPR/Cas9 in a Humanized Mouse Model Ameliorates α1-antitrypsin Deficiency Phenotype

α1-antitrypsin (AAT) is a circulating serine protease inhibitor secreted from the liver and important in preventing proteolytic neutrophil elastase associated tissue damage, primarily in lungs. In humans, AAT is encoded by the SERPINA1 (hSERPINA1) gene in which a point mutation (commonly referred to as PiZ) causes aggregation of the miss-folded protein in hepatocytes resulting in subsequent liver damage. In an attempt to rescue the pathologic liver phenotype of a mouse model of human AAT deficiency (AATD), we used adenovirus to deliver Cas9 and a guide-RNA (gRNA) molecule targeting hSERPINA1. Our single dose therapeutic gene editing approach completely reverted the phenotype associated with the PiZ mutation, including circulating transaminase and human AAT (hAAT) protein levels, liver fibrosis and protein aggregation. Furthermore, liver histology was significantly improved regarding inflammation and overall morphology in hSERPINA1 gene edited PiZ mice. Genomic analysis confirmed significant disruption to the hSERPINA1 transgene resulting in a reduction of hAAT protein levels and quantitative mRNA analysis showed a reduction in fibrosis and hepatocyte proliferation as a result of editing. Our findings indicate that therapeutic gene editing in hepatocytes is possible in an AATD mouse model.

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α1-antitrypsin (AAT) is a circulating protein secreted from the liver and important in preventing tissue damage in lungs.

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We used CRISPR/Cas9 to disrupt the gene of a mutant version of the protein to reverse liver pathology in a mouse model of human AAT deficiency (AATD)

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Our gene editing approach reverted the AATD pathology and genomic analysis confirmed significant disruption to the gene.

In an attempt to treat a pathologic liver disease called α1-antitrypsin deficiency (AATD) in a mouse model of the human disease, we used CRISPR/Cas9 technology to remove a mutant form of hSERPINA1, which causes AATD in the mouse. Our gene editing approach reverted the disease associated with the mutated gene and we saw a reversal in liver fibrosis and mutant protein aggregation. Our findings in a mouse model indicate that therapeutic gene removal, by editing out a mutated form of the gene, in liver cells is possible.

Abstract 240: Functional significance of co-occurring mutations in PIK3CA and MAP3K1 in breast cancer

PI3Kα signalling pathway is frequently hyper-activated in breast cancer (BrCa) with mutations of PIK3CA (∼45%) frequently found in luminal A BrCa samples. Genomic studies have also uncovered inactivating mutations in MAP3K1 (13-20%) and MAP2K4 (∼8%), two upstream kinases of the JNK apoptotic pathway in luminal A BrCa samples and co-occurring mutation of PIK3CA and MAP3K1 are found in ∼11% of PIK3CA mutants (TCGA). How these two alterations cooperate to promote tumorigenesis and impact the sensitivity to PI3Kα(AZD8835) and AKT (AZD5363) inhibitors is currently unknown. Using siRNA targeting and precise gene editing we have knocked down MAP3K1 in PIK3CA mutant cell lines to create in vitro models reflecting the mutational status of PIK3CA and MAP3K1 in BrCa patients. MAP3K1-deficient cells exhibited increased proliferation rate and decreased sensitivity to AZD8835 compared with parental control cells. In addition, mechanistic analysis revealed that siRNA mediated depletion of MAP3K1 enhances AKT phosphorylation and downstream signalling (i.e. pPRAS40, pFoxO1/FoxO3a) and provides resistance to AZD8835-mediated pathway inhibition. Using in vitro 3D-breast cancer organoid models we have found that MAP3K1 depletion increases overall acinar volume and counteracts AZD8835-mediated reduction of acinar growth. MAP3K1 deficient acini exhibited high pAKT levels in the presence of AZD8835 compared with control acini validating observations in 2D. Remarkably, whereas in control acini pAKT+ cells were restricted to the basal compartment, MAP3K1 deficient acini also exhibited pAKT+ cells in the luminal compartment suggesting anoikis resistance which is a hallmark in early stages of tumorigenesis. Elucidating the mechanistic basis for these clinically co-occurring mutations will provide insights into the mechanisms contributing to the oncogenic role of the PI3K pathway and future patient selection strategies.

Citation Format: Alvaro Avivar-Valderas, Robert McEwen, Amir Taheri-Ghahfarokhi, Ambar Ahmed, Daniel Stetson, Brian Dougherty, Marcello Maresca, Kevin Hudson, Francisco Cruzalegui. Functional significance of co-occurring mutations in PIK3CA and MAP3K1 in breast cancer. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 240.

Expanding the Living Donor Pool "Second Act": Laparoscopic Donor Nephrectomy and ABO-Incompatible Kidney Transplantation Improve Donor Recruitment

BACKGROUND

To safely expand our living donor pool, we recently decided to work on 3 areas: analysis of causes of exclusion of potential donors, the results of which we recently published, introduction of laparoscopic donor nephrectomy (LDN), and ABO-incompatible (ABOi) transplantation. We sought to determine the impact of the new strategy on living donor recruitment and transplantation during over a 10-year period at a single institution.

METHODS

From January 2005 to September 2014, we evaluated 131 living donors. Of these, 80 (61%) were genetically related, 51 (39%) unrelated, 119 (91%) ABO compatible (ABOc), 12 ABOi (9%). The analysis was divided into 2 eras: era 1, 2005-2010 (n = 53) included the use of open lumbotomy and acceptance of ABOc only; and era 2, 2011-2014 (n = 78), which saw the introduction of LDN and ABOi transplantation.

RESULTS

Forty-five (34%) potential candidates successfully donated, 67 (51%) were excluded, and 19 (15%) were actively undergoing evaluation. Overall, 53 potential donors were evaluated in era 1 (8.8 donors/year), 78 in era 2 (19.5 donors/year). There were fewer excluded donors in era 2 vs era 1 (62% era 1 vs 44% era 2), and living donor kidney transplantation (LDKT) significantly increased in era 2 vs era 1 (3.3/year era 1 vs 7.1/year era 2). The establishment of an ABOi LDKT program led to a 15% increase of evaluations in era 2 (12/78 donors).

CONCLUSIONS

LDN along with ABOi LDKT allowed for an improvement in recruitment of living donors and corresponding LDKT.

Managing atypical and typical herpetic central nervous system infections: results of a multinational study

There have been many studies pertaining to the management of herpetic meningoencephalitis (HME), but the majority of them have focussed on virologically unconfirmed cases or included only small sample sizes. We have conducted a multicentre study aimed at providing management strategies for HME. Overall, 501 adult patients with PCR-proven HME were included retrospectively from 35 referral centres in 10 countries; 496 patients were found to be eligible for the analysis. Cerebrospinal fluid (CSF) analysis using a PCR assay yielded herpes simplex virus (HSV)-1 DNA in 351 patients (70.8%), HSV-2 DNA in 83 patients (16.7%) and undefined HSV DNA type in 62 patients (12.5%). A total of 379 patients (76.4%) had at least one of the specified characteristics of encephalitis, and we placed these patients into the encephalitis presentation group. The remaining 117 patients (23.6%) had none of these findings, and these patients were placed in the nonencephalitis presentation group. Abnormalities suggestive of encephalitis were detected in magnetic resonance imaging (MRI) in 83.9% of the patients and in electroencephalography (EEG) in 91.0% of patients in the encephalitis presentation group. In the nonencephalitis presentation group, MRI and EEG data were suggestive of encephalitis in 33.3 and 61.9% of patients, respectively. However, the concomitant use of MRI and EEG indicated encephalitis in 96.3 and 87.5% of the cases with and without encephalitic clinical presentation, respectively. Considering the subtle nature of HME, CSF HSV PCR, EEG and MRI data should be collected for all patients with a central nervous system infection.

Ruminococcus gnavus E1 modulates mucin expression and intestinal glycosylation

AIMS

The molecular cross-talk between commensal bacteria and the gut play an important role in the maintenance of the intestinal homeostasis and general health. Here, we studied the impact of a major Gram-positive anaerobic bacterium of the human gut microbiota, that is, Ruminococcus gnavus on the glycosylation pattern and the production of intestinal mucus by the goblet cells.

METHODS AND RESULTS

Our results showed that R. gnavus E1 specifically increases the expression and the glycosylation level of the intestinal glyco-conjugates by goblet cells in the colonic mucosa of mono-associated mice with R. gnavus E1 as well as in human HT29-MTX cells. Such an effect was mediated through induction of the level of mRNA encoding for the major intestinal gel-forming mucin such as MUC2 and various glycosyltransferase enzymes.

CONCLUSIONS

This study demonstrates for the first time that R. gnavus E1 possess the ability to modulate the glycosylation profile of the glyco-conjugate molecules and mucus in goblet cells.

SIGNIFICANCE AND IMPACT OF THE STUDY

Furthermore, we demonstrated that R. gnavus E1 modified specifically the glycosylation pattern and MUC2 expression by means of a small soluble factor of peptidic nature (<3 kDa) and heat stable in the HT29-MTX cell.

High-efficiency counterselection recombineering for site-directed mutagenesis in bacterial artificial chromosomes

Whereas bacterial artificial chromosomes (BACs) offer many advantages in studies of gene and protein function, generation of seamless, precisely mutated BACs has been difficult. Here we describe a counterselection-based recombineering method and its accompanying reagents. After identifying intramolecular recombination as the major problem in counterselection, we built a strategy to reduce these unwanted events by expressing Redβ alone at the crucial step. We enhanced this method by using phosphothioated oligonucleotides, using a sequence-altered rpsL counterselection gene and developing online software for oligonucleotide design. We illustrated this method by generating transgenic mammalian cell lines carrying small interfering RNA-resistant and point-mutated BAC transgenes. Using this approach, we generated mutated TACC3 transgenes to identify phosphorylation-specific spindle defects after knockdown of endogenous TACC3 expression. Our results highlight the complementary use of precisely mutated BAC transgenes and RNA interference in the study of cell biology at physiological expression levels and regulation.

Efficacy of the "body movement and perception" method in the treatment of fibromyalgia syndrome: an open pilot study

OBJECTIVES

Group exercises may be useful in fibromyalgia syndrome (FMS). The 'Body movement and perception' (BMP) method is based on low impact exercises, awareness of body perception and relaxation, aimed at treating small groups of patients following the Resseguier method (RM) and integrating RM with exercises derived from soft gymnastics. We assessed the effects of BMP method on FMS.

METHODS

40 women with FMS (age and disease duration: 51.7±7.2 and 4.9±3.8 years) participated in an open pilot study. BMP sessions were performer twice a week (50 minutes each) for 8 weeks. Patients were assessed at enrolment (T0) and at the end of the study (T1) by a self-administered questionnaire (temporal characteristics of pain, pain interference in working and recreational activities and in night-time rest, awareness of pain, fatigue, irritability, well-being, quality of movement, ability to focus on perception and to perceive whole body, postural selfcontrol, ability to relax) and a clinical evaluation (tender points, assumption of analgesics/NSAIDs, distribution of pain, pain in sitting and standing position, pain during postural passages and gait, postural body alignment, muscular contractures).

RESULTS

At T1, FMS patients significantly improved with respect to T0 in pain, fatigue, irritability, well-being, quality of movement, postural self-control, ability to relax mind and body, movement perception, tender point scores, assumption of analgesic/NSAIDs, body alignment and muscle contractures (p<0.05 for all the comparisons T1 versus T0).

CONCLUSIONS

In FMS patients, rehabilitation with BMP improves pain and well being, reduces the number of tender points and muscle contractures, thus it is useful in FMS management.

Targeted isolation of cloned genomic regions by recombineering for haplotype phasing and isogenic targeting

Studying genetic variations in the human genome is important for understanding phenotypes and complex traits, including rare personal variations and their associations with disease. The interpretation of polymorphisms requires reliable methods to isolate natural genetic variations, including combinations of variations, in a format suitable for downstream analysis. Here, we describe a strategy for targeted isolation of large regions (∼35 kb) from human genomes that is also applicable to any genome of interest. The method relies on recombineering to fish out target fosmid clones from pools and thereby circumvents the laborious need to plate and screen thousands of individual clones. To optimize the method, a new highly recombineering-efficient bacterial host, including inducible TrfA for fosmid copy number amplification, was developed. Various regions were isolated from human embryonic stem cell lines and a personal genome, including highly repetitive and duplicated ones. The maternal and paternal alleles at the MECP2/IRAK 1 loci were distinguished based on identification of novel allele-specific single-nucleotide polymorphisms in regulatory regions. Additionally, we applied further recombineering to construct isogenic targeting vectors for patient-specific applications. These methods will facilitate work to understand the linkage between personal variations and disease propensity, as well as possibilities for personal genome surgery.

Recombineering, transfection, Western, IP and ChIP methods for protein tagging via gene targeting or BAC transgenesis

Protein tagging offers many advantages for proteomic and regulomic research. Ideally, protein tagging is equivalent to having a high affinity antibody for every chosen protein. However, these advantages are compromised if the tagged protein is overexpressed, which is usually the case from cDNA expression vectors. Physiological expression of tagged proteins can be achieved by gene targeting to knock-in the protein tag or by BAC transgenesis. BAC transgenes usually retain the native gene architecture including all cis-regulatory elements as well as the exon-intron configurations. Consequently most BAC transgenes are authentically regulated (e.g. by transcription factors, cell cycle, miRNA) and can be alternatively spliced. Recombineering has become the method of choice for generating targeting constructs or modifying BACs. Here we present methods with detailed protocols for protein tagging by recombineering for BAC transgenesis and/or gene targeting, including the evaluation of tagged protein expression, the retrieval of associated protein complexes for mass spectrometry and the use of the tags in ChIP (chromatin immunoprecipitation).

Single-stranded heteroduplex intermediates in lambda Red homologous recombination

Background

The Red proteins of lambda phage mediate probably the simplest and most efficient homologous recombination reactions yet described. However the mechanism of dsDNA recombination remains undefined.

Results

Here we show that the Red proteins can act via full length single stranded intermediates to establish single stranded heteroduplexes at the replication fork. We created asymmetrically digestible dsDNA substrates by exploiting the fact that Redα exonuclease activity requires a 5' phosphorylated end, or is blocked by phosphothioates. Using these substrates, we found that the most efficient configuration for dsDNA recombination occurred when the strand that can prime Okazaki-like synthesis contained both homology regions on the same ssDNA molecule. Furthermore, we show that Red recombination requires replication of the target molecule.

Conclusions

Hence we propose a new model for dsDNA recombination, termed 'beta' recombination, based on the formation of ssDNA heteroduplexes at the replication fork. Implications of the model were tested using (i) an in situ assay for recombination, which showed that recombination generated mixed wild type and recombinant colonies; and (ii) the predicted asymmetries of the homology arms, which showed that recombination is more sensitive to non-homologies attached to 5' than 3' ends. Whereas beta recombination can generate deletions in target BACs of at least 50 kb at about the same efficiency as small deletions, the converse event of insertion is very sensitive to increasing size. Insertions up to 3 kb are most efficiently achieved using beta recombination, however at greater sizes, an alternative Red-mediated mechanism(s) appears to be equally efficient. These findings define a new intermediate in homologous recombination, which also has practical implications for recombineering with the Red proteins.

Indeterminate, subcentimetric focal liver lesions in cancer patients: additional role of contrast-enhanced ultrasound

PURPOSE

To evaluate whether the use of contrast-enhanced ultrasound (CEUS) could improve the characterization of indeterminate subcentimetric focal liver lesions (FLLs) seen with multidetector computed tomography (MDCT) in cancer patients.

MATERIALS AND METHODS

For 12 months all patients with extrahepatic tumors showing small (< 10 mm), indeterminate focal liver lesions on whole-body or abdominal computed tomography (CT) underwent immediate, targeted ultrasound (US) to rule out a cystic lesion. Whenever unenhanced US demonstrated a non-cystic lesion or failed to recognize any focal abnormality within the suspected area, CEUS was carried out. During the arterial phase, CEUS was focused on the area reflecting the CT finding, while the entire organ was explored during the portal-sinusoidal phase.

RESULTS

Among the 132 patients with MDCT evidence of indeterminate, subcentimetric focal liver lesions (206 lesions), US proved the cystic nature of 138 lesions in 87 patients. In 45 cases US failed to recognize any abnormality or cystic image and these subjects underwent CEUS. The CEUS results were confirmed by further assessment or follow-up for 43 / 45 patients (3 cysts, 8 hemangiomas, 47 metastases, 2 areas of focal steatosis, 2 eosinophilic necroses, 1 granuloma, 1 abscess, 1 fistula). CEUS failed to detect 3 lesions (1 metastasis and 2 benign lesions). In 8 cases CEUS recognized additional liver metastases.

CONCLUSION

CEUS can be helpful in demonstrating or excluding metastases in cancer patients with MDCT evidence of subcentimetric, indeterminate focal liver lesions.

Conformational adaptability of Redbeta during DNA annealing and implications for its structural relationship with Rad52

Single-strand annealing proteins, such as Redbeta from lambda phage or eukaryotic Rad52, play roles in homologous recombination. Here, we use atomic force microscopy to examine Redbeta quaternary structure and Redbeta-DNA complexes. In the absence of DNA, Redbeta forms a shallow right-handed helix. The presence of single-stranded DNA (ssDNA) disrupts this structure. Upon addition of a second complementary ssDNA, annealing generates a left-handed helix that incorporates 14 Redbeta monomers per helical turn, with each Redbeta monomer annealing approximately 11 bp of DNA. The smallest stable annealing intermediate requires 20 bp DNA and two Redbeta monomers. Hence, we propose that Redbeta promotes base pairing by first increasing the number of transient interactions between ssDNAs. Then, annealing is promoted by the binding of a second Redbeta monomer, which nucleates the formation of a stable annealing intermediate. Using threading, we identify sequence similarities between the RecT/Redbeta and the Rad52 families, which strengthens previous suggestions, based on similarities of their quaternary structures, that they share a common mode of action. Hence, our findings have implications for a common mechanism of DNA annealing mediated by single-strand annealing proteins including Rad52.

Symptoms accompanying fibromyalgia

OBJECTIVE

The objective of the study was to investigate the relationship between spontaneous and provoked pain in fibromyalgia and to evaluate the frequency of disturbances associated with muscle pain, including some disturbances which are not usually considered as typical symptoms associated with pain in fibromyalgia.

METHODS

In sixty-seven patients with fibromyalgia the severity of spontaneous pain was assessed by a visual analogue scale and the severity of provoked pain by an original method, which includes the evaluation of the number of tender points and the evaluation of the intensity of provoked pain. The method used to assess the severity of provoked pain is more sensitive than other methods currently used. The occurrence of accompanying symptoms was also evaluated. The investigation included the occurrence of paresthesias of the upper limbs, hemorrhoids and epistaxis, which are not usually considered as typical symptoms associated with fibromyalgia.

RESULTS

No significant correlation was observed between the severity of spontaneous and provoked pain. The following disturbances were more frequent in the examined patients than in general population: headache, chronic fatigue, sleep disorders, irritable bowel syndrome, restless legs syndrome, paresthesias in the upper limbs, hemorrhoids and epistaxis.

CONCLUSIONS

Spontaneous and provoked pain should be considered two independent clinical features of fibromyalgia. Paresthesias in the upper limbs, hemorrhoids and epistaxis should be considered as typical symptoms associated with fibromyalgia. Hemorrhoids and epistaxis are frequently due to a diathesis characterized by laxity of connective tissues and fibromyalgia could be a consequence of such a diathesis.

Sensing X chromosome pairs before X inactivation via a novel X-pairing region of the Xic

Mammalian dosage compensation involves silencing of one of the two X chromosomes in females and is controlled by the X-inactivation center (Xic). The Xic, which includes Xist and its antisense transcription unit Tsix/Xite, somehow senses the number of X chromosomes and triggers Xist up-regulation from one of the two X chromosomes in females. We found that a segment of the mouse Xic lying several hundred kilobases upstream of Xist brings the two Xics together before the onset of X inactivation. This region can autonomously drive Xic trans-interactions even as an ectopic single-copy transgene. Its introduction into male embryonic stem cells is strongly selected against, consistent with a possible role in trans-activating Xist. We propose that homologous associations driven by this novel X-pairing region (Xpr) of the Xic enable a cell to sense that more than one X chromosome is present and coordinate reciprocal Xist/Tsix expression.

Low power radiofrequency electromagnetic radiation for the treatment of pain due to osteoarthritis of the knee

OBJECTIVE

To investigate the analgesic effect of low power radiofrequency electromagnetic radiation (RF) in osteoarthritis (OA) of the knee.

METHODS

In a randomized study on 40 patients the analgesic effect of RF was compared with the effect of transcutaneous electrical nerve stimulation (TENS). RF and TENS applications were repeated every day for a period of 5 days. The therapeutic effect was evaluated by a visual analogue scale (VAS) and by Lequesne's index: tests were performed before, immediately after and 30 days after therapy.

RESULTS

RF therapy induced a statistically significant and long lasting decrease of VAS and of Lequesne's index; TENS induced a decrease of VAS and of Lequesne's index which was not statistically significant.

CONCLUSIONS

A therapeutic effect of RF was therefore demonstrated on pain and disability due to knee OA. This effect was better than the effect of TENS, which is a largely used analgesic technique. Such a difference of the therapeutic effect may be due to the fact that TENS acts only on superficial tissues and nerve terminals, while RF acts increasing superficial and deep tissue temperature.

[Nurse's coworking to electronic medical record]

Nephrologists need to register and look at a great number of clinical data. The use of electronic medical records may improve efficiency and reduce errors. Aim of our work is to report the experience of Villa Scassi Hospital in Genoa, where a "patient file" has been performed to improve nephrology practice management. The file contains all clinical records, laboratory and radiology data, therapy, dialysis clinics, in addition to reports of out-patients department. This system allowed a better efficiency in diagnosis and treatment of the patient. Moreover experience of nurses in employing electronic medical records is reported. A reduced number of errors was found in therapy administering, because of a only one data source for physicians and nurses.

Recombineering reagents for improved inducible expression and selection marker re-use in Schizosaccharomyces pombe

The fission yeast Schizosaccharomyces pombe is an excellent model organism for cell biology. However, its genetic toolbox is less developed than that of Saccharomyces cerevisiae. In the first part of this study we describe an improved inducible expression vector based on tetracycline regulation of the CaMV35S promoter, which is also capable of chromosomal integration and therefore works in minimal and in rich media. We found that anhydrotetracycline is a superior ligand for induction. Maximum expression levels were observed after 12 h in minimal media (EMM) and after 9 h in rich media (YES), which is faster than the nmt1 promoter system. The system was combined with a convenient recombineering-based subcloning strategy for ease of cloning. In the second part we present four template plasmids, pSVEM-bsd, pSVEM-nat, pSVEM-kan and pSVEM-hph, which harbour four recyclable disruption cassettes based on the Cre recombinase lox71/66 strategy for use in PCR targeting methods. Cre-mediated excision leaves a non-functional mutant lox site in the genome, allowing the reiterative usage of these cassettes for multiple targetings. These cassettes are also configured with dual eukaryotic/prokaryotic promoters so that they can be used for recombineering in E. coli. Amongst other purposes, this permits the rapid and convenient creation of targeting constructs with much longer homology arms for difficult and complex targetings in the Sz. pombe genome.

Accurate prediction of autologous stem cell apheresis yields using a double variable-dependent method assures systematic efficiency control of continuous flow collection procedures

BACKGROUND AND OBJECTIVES

Stem cell collection is a standard procedure for the procurement of autologous grafts to rescue myelosuppression induced by high-dose treatments. Accurate prediction of collection yields may contribute to optimize planning and quality control of collection.

MATERIALS AND METHODS

Data of 313 autologous haematopoietic stem cell (AHSC) evaluable collections performed in 208 patients with haematologic and non-haematologic neoplasms from seven centres were prospectively analysed to test the accuracy of yield predictions generated by a formula that required the input of peripheral blood (PB) CD34+ cell precount and desired PB volume to be processed. Data were matched in a standard linear regression, in a zero-point regression analysis and tested for prediction accuracy. Further 165 AHSC collections were analysed on a single-centre basis, using yield predictions as reference standards.

RESULTS

Analysis showed high levels of correlation between measured collection yields (my) and predictions (py) (R = 0.85; P = 0.000000) as well as high degree of prediction accuracy (my vs. py at paired t-test: P = 0.114781; median my/py ratio = 1.23). Analysis of additional 165 AHSC collections on a single-centre basis showed that the analysed centres had 70% or more measured yields comprising the 0.6-1.8 interval of the my/py ratio. The observance of the 'efficiency' my/py interval assured collection quality control in these centres confirming the reliability of the method.

CONCLUSIONS

This prediction method generates accurate and immediate yield predictions allowing collection planning and rapid efficiency control. As a consequence of our study, four centres out of seven use the described method to plan both leukapheresis number and single-procedure blood processing volume while the remaining three centres plan leukapheresis number on the basis of our predictions, maintaining a fixed single-procedure 200 ml/kg blood volume processing, according to their centre AHSC collection policy.

A comparison of ultrasonography and magnetic resonance imaging in the evaluation of temporomandibular joint involvement in rheumatoid arthritis and psoriatic arthritis

OBJECTIVE

To define the diagnostic value of ultrasonographic (US) examination in comparison with magnetic resonance imaging (MRI) for the assessment of temporomandibular joint (TMJ) involvement in rheumatoid arthritis (RA) and psoriatic arthritis (PsA).

METHODS

MRI and US examinations were performed in 33 patients (22 with RA and 11 with PsA). Alterations of the disc, alterations of the condyle and joint effusion were evaluated.

RESULTS

Pathological changes of the TMJ were observed by MRI in 24 patients and by US in 31 patients. The sensitivity and specificity of US were calculated in comparison with MRI. The sensitivity was 72.2% and the specificity was 60% in the assessment of pathological changes of the TMJ. The sensitivity was 69.6% with specificity of 30.0% in the assessment of alterations of the disc; the sensitivity was 70.6% with specificity of 75.0% in the assessment of joint effusion. Significant concordance was not observed in the assessment of condylar alterations.

CONCLUSIONS

US imaging appears able to detect different pathological changes of the TMJ and may be considered an important diagnostic tool for clinical evaluation of the TMJ in RA and PsA.

Role of the thyroid-stimulating hormone receptor signaling in development and differentiation of the thyroid gland

The thyroid-stimulating hormone/thyrotropin (TSH) is the most relevant hormone in the control of thyroid gland physiology in adulthood. TSH effects on the thyroid gland are mediated by the interaction with a specific TSH receptor (TSHR). We studied the role of TSHTSHR signaling on gland morphogenesis and differentiation in the mouse embryo using mouse lines deprived either of TSH (pit(dw)pit(dw)) or of a functional TSHR (tshr(hyt)tshr(hyt) and TSHR-knockout lines). The results reported here show that in the absence of either TSH or a functional TSHR, the thyroid gland develops to a normal size, whereas the expression of thyroperoxidase and the sodium/iodide symporter are reduced greatly. Conversely, no relevant changes are detected in the amounts of thyroglobulin and the thyroid-enriched transcription factors TTF-1, TTF-2, and Pax8. These data suggest that the major role of the TSH/TSHR pathway is in controlling genes involved in iodide metabolism such as sodium/iodide symporter and thyroperoxidase. Furthermore, our data indicate that in embryonic life TSH does not play an equivalent role in controlling gland growth as in the adult thyroid.

The concept of pain in the 17th century

The 17th century is very important in the history of sensation and pain. Philosophers, as Descartes, Hobbes, Spinoza, defined a new philosophy of science. Physicians of the iatro-chemical school introduced the first principles of biochemistry, tied to the sensations. Physicians of the iatro-mechanical school postulated a really modern concept: the importance of nerve juices in sensibility and pain.