Helmut Fuchs

Publications of Helmut Fuchs

• Cardiopulmonary dysfunction in the Osteogenesis Imperfecta mouse model Aga2 and human patients are caused by bone-independent mechanisms.

  Authors: Frank Thiele, Christian M Cohrs, Armando Flor, Thomas S Lisse, Gerhard K H Przemeck, Marion Horsch, Anja Schrewe, Valerie Gailus-Durner, Boris Ivandic, Hugo A Katus, Wolfgang Wurst, Catherine Reisenberg, Hollis Chaney, Helmut Fuchs, Wolfgang Hans, Johannes Beckers, Joan C Marini, Martin Hrabé de Angelis

  Human molecular genetics. 05/2012;

  Osteogenesis imperfecta (OI) is an inherited connective tissue disorder with skeletal dysplasia of varying severity, predominantly caused by mutations in the collagen I genes (COL1A1/COL1A2).Osteogenesis imperfecta (OI) is an inherited connective tissue disorder with skeletal dysplasia of varying severity, predominantly caused by mutations in the collagen I genes (COL1A1/COL1A2). Extraskeletal findings like cardiac and pulmonary complications are generally considered to be significant secondary features. Aga2, a murine model for human OI, was systemically analyzed in the German Mouse Clinic by means of in vivo and in vitro examinations of the cardiopulmonary system, to identify novel mechanisms accounting for perinatal lethality. Pulmonary and especially cardiac fibroblast of perinatal lethal Aga2/+ animals display a strong down-regulation of Col1a1 transcripts in vivo and in vitro, resulting in loss of extracellular matrix integrity. In addition, dysregulated gene expression of Nppa, different types of collagen and Agt in heart and lung tissue supports a bone-independent vicious cycle of heart dysfunction including hypertrophy, loss of myocardial matrix integrity, pulmonary hypertension, pneumonia and hypoxia leading to death in Aga2. These murine findings are corroborated by a pediatric OI cohort study, displaying significant progressive decline of pulmonary function and restrictive pulmonary disease independent of scoliosis. Most participants show mild cardiac valvular regurgitation, independent of pulmonary and skeletal findings. Data obtained from human OI patients and the mouse model Aga2 provide novel evidence for primary effects of type I collagen mutations on heart and lung. The findings will have potential benefits of anticipatory clinical exams and early intervention in OI patients.

• New mouse models for metabolic bone diseases generated by genome-wide ENU mutagenesis.

  Authors: Sibylle Sabrautzki, Isabel Rubio-Aliaga, Wolfgang Hans, Helmut Fuchs, Birgit Rathkolb, Julia Calzada-Wack, Christian M Cohrs, Matthias Klaften, Hartwig Seedorf, Sebastian Eck, Ana Benet-Pagès, Jack Favor, Irene Esposito, Tim M Strom, Eckhard Wolf, Bettina Lorenz-Depiereux, Martin Hrabě de Angelis

  Mammalian genome : official journal of the International Mammalian Genome Society. 04/2012;

  Metabolic bone disorders arise as primary diseases or may be secondary due to a multitude of organ malfunctions. Animal models are required to understand the molecular mechanisms responsible for theMetabolic bone disorders arise as primary diseases or may be secondary due to a multitude of organ malfunctions. Animal models are required to understand the molecular mechanisms responsible for the imbalances of bone metabolism in disturbed bone mineralization diseases. Here we present the isolation of mutant mouse models for metabolic bone diseases by phenotyping blood parameters that target bone turnover within the large-scale genome-wide Munich ENU Mutagenesis Project. A screening panel of three clinical parameters, also commonly used as biochemical markers in patients with metabolic bone diseases, was chosen. Total alkaline phosphatase activity and total calcium and inorganic phosphate levels in plasma samples of F1 offspring produced from ENU-mutagenized C3HeB/FeJ male mice were measured. Screening of 9,540 mice led to the identification of 257 phenodeviants of which 190 were tested by genetic confirmation crosses. Seventy-one new dominant mutant lines showing alterations of at least one of the biochemical parameters of interest were confirmed. Fifteen mutations among three genes (Phex, Casr, and Alpl) have been identified by positional-candidate gene approaches and one mutation of the Asgr1 gene, which was identified by next-generation sequencing. All new mutant mouse lines are offered as a resource for the scientific community.

• Neurobeachin, a regulator of synaptic protein targeting, is associated with body fat mass and feeding behavior in mice and body-mass index in humans.

  Authors: Pawel K Olszewski, Jan Rozman, Josefin A Jacobsson, Birgit Rathkolb, Siv Strömberg, Wolfgang Hans, Anica Klockars, Johan Alsiö, Ulf Risérus, Lore Becker [......] Robert Fredriksson, Eckhard Wolf, Thomas Klopstock, Wolfgang Wurst, Allen S Levine, Claude Marcus, Martin Hrabě de Angelis, Martin Klingenspor, Helgi B Schiöth, Manfred W Kilimann

  PLoS genetics. 03/2012; 8(3):e1002568.

  Neurobeachin (Nbea) regulates neuronal membrane protein trafficking and is required for the development and functioning of central and neuromuscular synapses. In homozygous knockout (KO) mice, NbeaNeurobeachin (Nbea) regulates neuronal membrane protein trafficking and is required for the development and functioning of central and neuromuscular synapses. In homozygous knockout (KO) mice, Nbea deficiency causes perinatal death. Here, we report that heterozygous KO mice haploinsufficient for Nbea have higher body weight due to increased adipose tissue mass. In several feeding paradigms, heterozygous KO mice consumed more food than wild-type (WT) controls, and this consumption was primarily driven by calories rather than palatability. Expression analysis of feeding-related genes in the hypothalamus and brainstem with real-time PCR showed differential expression of a subset of neuropeptide or neuropeptide receptor mRNAs between WT and Nbea+/- mice in the sated state and in response to food deprivation, but not to feeding reward. In humans, we identified two intronic NBEA single-nucleotide polymorphisms (SNPs) that are significantly associated with body-mass index (BMI) in adult and juvenile cohorts. Overall, data obtained in mice and humans suggest that variation of Nbea abundance or activity critically affects body weight, presumably by influencing the activity of feeding-related neural circuits. Our study emphasizes the importance of neural mechanisms in body weight control and points out NBEA as a potential risk gene in human obesity.

• Comparison of particle-exposure triggered pulmonary and systemic inflammation in mice fed with three different diets.

  Authors: Alexander A Götz, Jan Rozman, Heiko G Rödel, Helmut Fuchs, Valérie Gailus-Durner, Martin Hrabě de Angelis, Martin Klingenspor, Tobias Stoeger

  Particle and fibre toxicology. 09/2011; 8:30.

  Obesity can be linked to disease risks such as diabetes and cardiovascular disorders, but recently, the adipose tissue (AT) macrophage also emerges as actively participating in inflammation andObesity can be linked to disease risks such as diabetes and cardiovascular disorders, but recently, the adipose tissue (AT) macrophage also emerges as actively participating in inflammation and immune function, producing pro- and anti-inflammatory factors. Connections between the AT and chronic lung diseases, like emphysema and asthma and a protective role of adipocyte-derived proteins against acute lung injury were suggested.In this study we addressed the question, whether a diet challenge increases the inflammatory response in the alveolar and the blood compartment in response to carbon nanoparticles (CNP), as a surrogate for ambient/urban particulate air pollutants. Mice were fed a high caloric carbohydrate-rich (CA) or a fat-rich (HF) diet for six weeks and were compared to mice kept on a purified low fat (LF) diet, respectively. Bronchoalveolar lavage (BAL) and blood samples were taken 24 h after intratracheal CNP instillation and checked for cellular and molecular markers of inflammation. The high caloric diets resulted in distinct effects when compared with LF mice, respectively: CA resulted in increased body and fat mass without affecting blood cellular immunity. Conversely, HF activated the blood system, increasing lymphocyte and neutrophil counts, and resulted in slightly increased body fat content. In contrast to higher pro-inflammatory BAL Leptin in CA and HF mice, on a cellular level, both diets did not lead to an increased pro-inflammatory basal status in the alveolar compartment per se, nor did result in differences in the particle-triggered response. However both diets resulted in a disturbance of the alveolar capillary barrier as indicated by enhanced BAL protein and lactate-dehydrogenase concentrations. Systemically, reduced serum Adiponectin in HF mice might be related to the observed white blood cell increase. The increase in BAL pro-inflammatory factors in high caloric groups and reductions in serum concentrations of anti-inflammatory factors in HF mice, clearly show diet-specific effects, pointing towards augmented systemic inflammatory conditions. Our data suggest that extended feeding periods, leading to manifest obesity, are necessary to generate an increased susceptibility to particle-induced lung inflammation; although the diet-challenge already was efficient in driving pro-inflammatory systemic events.

• The transcription factor Smad-interacting protein 1 controls pain sensitivity via modulation of DRG neuron excitability.

  Authors: Monika Jeub, Michael Emrich, Bruno Pradier, Omneya Taha, Valerie Gailus-Durner, Helmut Fuchs, Martin Hrabe de Angelis, Danny Huylebroeck, Andreas Zimmer, Heinz Beck, Ildiko Racz

  Pain. 08/2011; 152(10):2384-98.

  The perception of pain is initiated by the transduction of noxious stimuli through specialized ion channels and receptors expressed by primary nociceptive neurons. The molecular mechanisms thatThe perception of pain is initiated by the transduction of noxious stimuli through specialized ion channels and receptors expressed by primary nociceptive neurons. The molecular mechanisms that orchestrate the expression and function of ion channels relevant for pain processing are poorly understood. We demonstrate here a central role of the transcription factor Smad-interacting protein 1 (Sip1/Zfhx1b/Zeb2), a 2-handed zinc finger DNA-binding protein with essential functions in neural crest and forebrain development, in controlling nociceptive neuron excitability and pain sensitivity. Mutant mice lacking 1 Zfhx1b allele displayed decreased thermal pain responses, whereas mechanical pain was unaffected. In parallel, repetitive firing of capsaicin/heat-sensitive nociceptive DRG neurons was markedly impaired. Analysis of the voltage-gated currents underlying repetitive firing revealed a significant increase in persistent sodium currents and a reduction in delayed rectifier potassium currents. Modeling experiments in conjunction with experimental results suggest that these changes cause a depolarization-induced block of action potential propagation past the DRG axon T-junction. These data suggest that Sip1 controls the transduction properties of heat-sensitive primary sensory neurons and thus thermal pain sensitivity in a novel manner via coordinated changes in DRG-neuron voltage-gated ion channels.

• Requirement of the RNA-editing enzyme ADAR2 for normal physiology in mice.

  Authors: Marion Horsch, Peter H Seeburg, Thure Adler, Juan Antonio Aguilar-Pimentel, Lore Becker, Julia Calzada-Wack, Lilian Garrett, Alexander Götz, Wolfgang Hans, Miyoko Higuchi [......] Martin Mempel, Markus Ollert, Holger Schulz, Eckhard Wolf, Wolfgang Wurst, Andreas Zimmer, Valérie Gailus-Durner, Helmut Fuchs, Martin Hrabe de Angelis, Johannes Beckers

  The Journal of biological chemistry. 04/2011; 286(21):18614-22.

  ADAR2, an RNA editing enzyme that converts specific adenosines to inosines in certain pre-mRNAs, often leading to amino acid substitutions in the encoded proteins, is mainly expressed in brain. OfADAR2, an RNA editing enzyme that converts specific adenosines to inosines in certain pre-mRNAs, often leading to amino acid substitutions in the encoded proteins, is mainly expressed in brain. Of all ADAR2-mediated edits, a single one in the pre-mRNA of the AMPA receptor subunit GluA2 is essential for survival. Hence, early postnatal death of mice lacking ADAR2 is averted when the critical edit is engineered into both GluA2 encoding Gria2 alleles. Adar2(-/-)/Gria2(R/R) mice display normal appearance and life span, but the general phenotypic effects of global lack of ADAR2 have remained unexplored. Here we have employed the Adar2(-/-)/Gria2(R/R) mouse line, and Gria2(R/R) mice as controls, to study the phenotypic consequences of loss of all ADAR2-mediated edits except the critical one in GluA2. Our extended phenotypic analysis covering ∼320 parameters identified significant changes related to absence of ADAR2 in behavior, hearing ability, allergy parameters and transcript profiles of brain.

• Missing-in-metastasis MIM/MTSS1 promotes actin assembly at intercellular junctions and is required for integrity of kidney epithelia.

  Authors: Juha Saarikangas, Pieta K Mattila, Markku Varjosalo, Miia Bovellan, Janne Hakanen, Julia Calzada-Wack, Monica Tost, Luise Jennen, Birgit Rathkolb, Wolfgang Hans [......] Eckhard Wolf, Martin Hrabé de Angelis, Mikko J Frilander, Harri Savilahti, Hannu Sariola, Kirsi Sainio, Sanna Lehtonen, Jussi Taipale, Marjo Salminen, Pekka Lappalainen

  Journal of cell science. 03/2011; 124(Pt 8):1245-55.

  MIM/MTSS1 is a tissue-specific regulator of plasma membrane dynamics, whose altered expression levels have been linked to cancer metastasis. MIM deforms phosphoinositide-rich membranes through itsMIM/MTSS1 is a tissue-specific regulator of plasma membrane dynamics, whose altered expression levels have been linked to cancer metastasis. MIM deforms phosphoinositide-rich membranes through its I-BAR domain and interacts with actin monomers through its WH2 domain. Recent work proposed that MIM also potentiates Sonic hedgehog (Shh)-induced gene expression. Here, we generated MIM mutant mice and found that full-length MIM protein is dispensable for embryonic development. However, MIM-deficient mice displayed a severe urinary concentration defect caused by compromised integrity of kidney epithelia intercellular junctions, which led to bone abnormalities and end-stage renal failure. In cultured kidney epithelial (MDCK) cells, MIM displayed dynamic localization to adherens junctions, where it promoted Arp2/3-mediated actin filament assembly. This activity was dependent on the ability of MIM to interact with both membranes and actin monomers. Furthermore, results from the mouse model and cell culture experiments suggest that full-length MIM is not crucial for Shh signaling, at least during embryogenesis. Collectively, these data demonstrate that MIM modulates interplay between the actin cytoskeleton and plasma membrane to promote the maintenance of intercellular contacts in kidney epithelia.

• Mouse phenotyping.

  Authors: Helmut Fuchs, Valérie Gailus-Durner, Thure Adler, Juan Antonio Aguilar-Pimentel, Lore Becker, Julia Calzada-Wack, Patricia Da Silva-Buttkus, Frauke Neff, Alexander Götz, Wolfgang Hans [......] Elisabeth Kremmer, Martin Mempel, Susanne Neschen, Markus Ollert, Holger Schulz, Karsten Suhre, Eckhard Wolf, Wolfgang Wurst, Andreas Zimmer, Martin Hrabě de Angelis

  Methods (San Diego, Calif.). 02/2011; 53(2):120-35.

  Model organisms like the mouse are important tools to learn more about gene function in man. Within the last 20 years many mutant mouse lines have been generated by different methods such as ENUModel organisms like the mouse are important tools to learn more about gene function in man. Within the last 20 years many mutant mouse lines have been generated by different methods such as ENU mutagenesis, constitutive and conditional knock-out approaches, knock-down, introduction of human genes, and knock-in techniques, thus creating models which mimic human conditions. Due to pleiotropic effects, one gene may have different functions in different organ systems or time points during development. Therefore mutant mouse lines have to be phenotyped comprehensively in a highly standardized manner to enable the detection of phenotypes which might otherwise remain hidden. The German Mouse Clinic (GMC) has been established at the Helmholtz Zentrum München as a phenotyping platform with open access to the scientific community (www.mousclinic.de; [1]). The GMC is a member of the EUMODIC consortium which created the European standard workflow EMPReSSslim for the systemic phenotyping of mouse models (http://www.eumodic.org/[2]).

• A novel N-ethyl-N-nitrosourea-induced mutation in phospholipase Cγ2 causes inflammatory arthritis, metabolic defects, and male infertility in vitro in a murine model.

  Authors: Koichiro Abe, Helmut Fuchs, Auke Boersma, Wolfgang Hans, Philipp Yu, Svetoslav Kalaydjiev, Matthias Klaften, Thure Adler, Julia Calzada-Wack, Ilona Mossbrugger [......] Irene Esposito, Martin Klingenspor, Eckhard Wolf, Wolfgang Wurst, Valerie Gailus-Durner, Matilda Katan, Susan Marschall, Dian Soewarto, Sibylle Wagner, Martin Hrabě de Angelis

  Arthritis and rheumatism. 02/2011; 63(5):1301-11.

  It is difficult to identify a single causative factor for inflammatory arthritis because of the multifactorial nature of the disease. This study was undertaken to dissect the molecular complexity ofIt is difficult to identify a single causative factor for inflammatory arthritis because of the multifactorial nature of the disease. This study was undertaken to dissect the molecular complexity of systemic inflammatory disease, utilizing a combined approach of mutagenesis and systematic phenotype screening in a murine model. In a large-scale N-ethyl-N-nitrosourea mutagenesis project, the Ali14 mutant mouse strain was established because of dominant inheritance of spontaneous swelling and inflammation of the hind paws. Genetic mapping and subsequent candidate gene sequencing were conducted to find the causative gene, and systematic phenotyping of Ali14/+ mice was performed in the German Mouse Clinic. A novel missense mutation in the phospholipase Cγ2 gene (Plcg2) was identified in Ali14/+ mice. Because of the hyperreactive external entry of calcium observed in cultured B cells and other in vitro experiments, the Ali14 mutation is thought to be a novel gain-of-function allele of Plcg2. Findings from systematic screening of Ali14/+ mice demonstrated various phenotypic changes: an abnormally high T cell:B cell ratio, up-regulation of Ig, alterations in body composition, and a reduction in cholesterol and triglyceride levels in peripheral blood. In addition, spermatozoa from Ali14/+ mice failed to fertilize eggs in vitro, despite the normal fertility of the Ali14/+ male mice in vivo. These results suggest that the Plcg2-mediated pathways play a crucial role in various metabolic and sperm functions, in addition to initiating and maintaining the immune system. These findings may indicate the importance of the Ali14/+ mouse strain as a model for systemic inflammatory diseases and inflammation-related metabolic changes in humans.

• Toxicity modelling of Plk1-targeted therapies in genetically engineered mice and cultured primary mammalian cells.

  Authors: Monika Raab, Sven Kappel, Andrea Krämer, Mourad Sanhaji, Yves Matthess, Elisabeth Kurunci-Csacsko, Julia Calzada-Wack, Birgit Rathkolb, Jan Rozman, Thure Adler [......] Eckhard Wolf, Nicole Sänger, Florian Prinz, Martin Hrabě de Angelis, Jost Seibler, Juping Yuan, Martin Bergmann, Rainald Knecht, Bertolt Kreft, Klaus Strebhardt

  Nature communications. 01/2011; 2:395.

  High attrition rates of novel anti-cancer drugs highlight the need for improved models to predict toxicity. Although polo-like kinase 1 (Plk1) inhibitors are attractive candidates for drugHigh attrition rates of novel anti-cancer drugs highlight the need for improved models to predict toxicity. Although polo-like kinase 1 (Plk1) inhibitors are attractive candidates for drug development, the role of Plk1 in primary cells remains widely unexplored. Therefore, we evaluated the utility of an RNA interference-based model to assess responses to an inducible knockdown (iKD) of Plk1 in adult mice. Here we show that Plk1 silencing can be achieved in several organs, although adverse events are rare. We compared responses in Plk1-iKD mice with those in primary cells kept under controlled culture conditions. In contrast to the addiction of many cancer cell lines to the non-oncogene Plk1, the primary cells' proliferation, spindle assembly and apoptosis exhibit only a low dependency on Plk1. Responses to Plk1-depletion, both in cultured primary cells and in our iKD-mouse model, correspond well and thus provide the basis for using validated iKD mice in predicting responses to therapeutic interventions.

• Immune modulation by Fas ligand reverse signaling: lymphocyte proliferation is attenuated by the intracellular Fas ligand domain.

  Authors: Katharina Lückerath, Vladimir Kirkin, Inga Maria Melzer, Frederic B Thalheimer, Dagmar Siele, Wiebke Milani, Thure Adler, Antonio Aguilar-Pimentel, Marion Horsch, Geert Michel [......] Markus Ollert, Valerie Gailus-Durner, Helmut Fuchs, Martin Hrabe de Angelis, Frank J T Staal, Krishnaraj Rajalingam, Anne-Odile Hueber, Lothar J Strobl, Ursula Zimber-Strobl, Martin Zörnig

  Blood. 10/2010; 117(2):519-29.

  Fas ligand (FasL) not only induces apoptosis in Fas receptor-bearing target cells, it is also able to transmit signals into the FasL-expressing cell via its intracellular domain (ICD). Recently, weFas ligand (FasL) not only induces apoptosis in Fas receptor-bearing target cells, it is also able to transmit signals into the FasL-expressing cell via its intracellular domain (ICD). Recently, we described a Notch-like proteolytic processing of FasL that leads to the release of the FasL ICD into the cytoplasm and subsequent translocation into the nucleus where it may influence gene transcription. To study the molecular mechanism underlying such reverse FasL signaling in detail and to analyze its physiological importance in vivo, we established a knockout/knockin mouse model, in which wild-type FasL was replaced with a deletion mutant lacking the ICD. Our results demonstrate that FasL ICD signaling impairs activation-induced proliferation in B and T cells by diminishing phosphorylation of phospholipase C γ, protein kinase C, and extracellular signal-regulated kinase 1/2. We also demonstrate that the FasL ICD interacts with the transcription factor lymphoid-enhancer binding factor-1 and inhibits lymphoid-enhancer binding factor-1-dependent transcription. In vivo, plasma cell numbers, generation of germinal center B cells, and, consequently, production of antigen-specific immunoglobulin M antibodies in response to immunization with T cell-dependent or T cell-independent antigen are negatively affected in presence of the FasL ICD, suggesting that FasL reverse signaling participates in negative fine-tuning of certain immune responses.

• CIN85 regulates dopamine receptor endocytosis and governs behaviour in mice.

  Authors: Noriaki Shimokawa, Kaisa Haglund, Sabine M Hölter, Caroline Grabbe, Vladimir Kirkin, Noriyuki Koibuchi, Christian Schultz, Jan Rozman, Daniela Hoeller, Chun-Hong Qiu [......] Andreas Brech, Mirko H H Schmidt, Helmut Fuchs, Valerie Gailus-Durner, Martin Klingenspor, Oliver Bogler, Wolfgang Wurst, Thomas Deller, Martin Hrabé de Angelis, Ivan Dikic

  The EMBO journal. 07/2010; 29(14):2421-32.

  Despite extensive investigations of Cbl-interacting protein of 85 kDa (CIN85) in receptor trafficking and cytoskeletal dynamics, little is known about its functions in vivo. Here, we report the studyDespite extensive investigations of Cbl-interacting protein of 85 kDa (CIN85) in receptor trafficking and cytoskeletal dynamics, little is known about its functions in vivo. Here, we report the study of a mouse deficient of the two CIN85 isoforms expressed in the central nervous system, exposing a function of CIN85 in dopamine receptor endocytosis. Mice lacking CIN85 exon 2 (CIN85(Deltaex2)) show hyperactivity phenotypes, characterized by increased physical activity and exploratory behaviour. Interestingly, CIN85(Deltaex2) animals display abnormally high levels of dopamine and D2 dopamine receptors (D2DRs) in the striatum, an important centre for the coordination of animal behaviour. Importantly, CIN85 localizes to the post-synaptic compartment of striatal neurons in which it co-clusters with D2DRs. Moreover, it interacts with endocytic regulators such as dynamin and endophilins in the striatum. Absence of striatal CIN85 causes insufficient complex formation of endophilins with D2DRs in the striatum and ultimately decreased D2DR endocytosis in striatal neurons in response to dopamine stimulation. These findings indicate an important function of CIN85 in the regulation of dopamine receptor functions and provide a molecular explanation for the hyperactive behaviour of CIN85(Deltaex2) mice.

• Urocortin 3 modulates social discrimination abilities via corticotropin-releasing hormone receptor type 2.

  Authors: Jan M Deussing, Johannes Breu, Claudia Kühne, Magdalena Kallnik, Mirjam Bunck, Lisa Glasl, Yi-Chun Yen, Mathias V Schmidt, Regine Zurmühlen, Annette M Vogl, Valérie Gailus-Durner, Helmut Fuchs, Sabine M Hölter, Carsten T Wotjak, Rainer Landgraf, Martin Hrabé de Angelis, Florian Holsboer, Wolfgang Wurst

  The Journal of neuroscience : the official journal of the Society for Neuroscience. 07/2010; 30(27):9103-16.

  Urocortin 3 (UCN3) is strongly expressed in specific nuclei of the rodent brain, at sites distinct from those expressing urocortin 1 and urocortin 2, the other endogenous ligands ofUrocortin 3 (UCN3) is strongly expressed in specific nuclei of the rodent brain, at sites distinct from those expressing urocortin 1 and urocortin 2, the other endogenous ligands of corticotropin-releasing hormone receptor type 2 (CRH-R2). To determine the physiological role of UCN3, we generated UCN3-deficient mice, in which the UCN3 open reading frame was replaced by a tau-lacZ reporter gene. By means of this reporter gene, the nucleus parabrachialis and the premammillary nucleus were identified as previously unknown sites of UCN3 expression. Additionally, the introduced reporter gene enabled the visualization of axonal projections of UCN3-expressing neurons from the superior paraolivary nucleus to the inferior colliculus and from the posterodorsal part of the medial amygdala to the principal nucleus of the bed nucleus of the stria terminalis, respectively. The examination of tau-lacZ reporter gene activity throughout the brain underscored a predominant expression of UCN3 in nuclei functionally connected to the accessory olfactory system. Male and female mice were comprehensively phenotyped but none of the applied tests provided indications for a role of UCN3 in the context of hypothalamic-pituitary-adrenocortical axis regulation, anxiety- or depression-related behavior. However, inspired by the prevalent expression throughout the accessory olfactory system, we identified alterations in social discrimination abilities of male and female UCN3 knock-out mice that were also present in male CRH-R2 knock-out mice. In conclusion, our results suggest a novel role for UCN3 and CRH-R2 related to the processing of social cues and to the establishment of social memories.

• Calcium oxalate stone formation in the inner ear as a result of an Slc26a4 mutation.

  Authors: Amiel A Dror, Yael Politi, Hashem Shahin, Danielle R Lenz, Silvia Dossena, Charity Nofziger, Helmut Fuchs, Martin Hrabé de Angelis, Markus Paulmichl, Steve Weiner, Karen B Avraham

  The Journal of biological chemistry. 05/2010; 285(28):21724-35.

  Calcium oxalate stone formation occurs under pathological conditions and accounts for more than 80% of all types of kidney stones. In the current study, we show for the first time that calciumCalcium oxalate stone formation occurs under pathological conditions and accounts for more than 80% of all types of kidney stones. In the current study, we show for the first time that calcium oxalate stones are formed in the mouse inner ear of a genetic model for hearing loss and vestibular dysfunction in humans. The vestibular system within the inner ear is dependent on extracellular tiny calcium carbonate minerals for proper function. Thousands of these biominerals, known as otoconia, are associated with the utricle and saccule sensory maculae and are vital for mechanical stimulation of the sensory hair cells. We show that a missense mutation within the Slc26a4 gene abolishes the transport activity of its encoded protein, pendrin. As a consequence, dramatic changes in mineral composition, size, and shape occur within the utricle and saccule in a differential manner. Although abnormal giant carbonate minerals reside in the utricle at all ages, in the saccule, a gradual change in mineral composition leads to a formation of calcium oxalate in adult mice. By combining imaging and spectroscopy tools, we determined the profile of mineral composition and morphology at different time points. We propose a novel mechanism for the accumulation and aggregation of oxalate crystals in the inner ear.

• Mutation of the Na(+)-K(+)-2Cl(-) cotransporter NKCC2 in mice is associated with severe polyuria and a urea-selective concentrating defect without hyperreninemia.

  Authors: Elisabeth Kemter, Birgit Rathkolb, Lise Bankir, Anja Schrewe, Wolfgang Hans, Christina Landbrecht, Matthias Klaften, Boris Ivandic, Helmut Fuchs, Valérie Gailus-Durner, Martin Hrabé de Angelis, Eckhard Wolf, Ruediger Wanke, Bernhard Aigner

  American journal of physiology. Renal physiology. 03/2010; 298(6):F1405-15.

  The bumetanide-sensitive Na(+)-K(+)-2Cl(-) cotransporter NKCC2, located in the thick ascending limb of Henle's loop, plays a critical role in the kidney's ability to concentrate urine. In humans,The bumetanide-sensitive Na(+)-K(+)-2Cl(-) cotransporter NKCC2, located in the thick ascending limb of Henle's loop, plays a critical role in the kidney's ability to concentrate urine. In humans, loss-of-function mutations of the solute carrier family 12 member 1 gene (SLC12A1), coding for NKCC2, cause type I Bartter syndrome, which is characterized by prenatal onset of a severe polyuria, salt-wasting tubulopathy, and hyperreninemia. In this study, we describe a novel chemically induced, recessive mutant mouse line termed Slc12a1(I299F) exhibiting late-onset manifestation of type I Bartter syndrome. Homozygous mutant mice are viable and exhibit severe polyuria, metabolic alkalosis, marked increase in plasma urea but close to normal creatininemia, hypermagnesemia, hyperprostaglandinuria, hypotension,, and osteopenia. Fractional excretion of urea is markedly decreased. In addition, calcium and magnesium excretions are more than doubled compared with wild-type mice, while uric acid excretion is twofold lower. In contrast to hyperreninemia present in human disease, plasma renin concentration in homozygotes is not increased. The polyuria observed in homozygotes may be due to the combination of two additive factors, a decrease in activity of mutant NKCC2 and an increase in medullary blood flow, due to prostaglandin-induced vasodilation, that impairs countercurrent exchange of urea in the medulla. In conclusion, this novel viable mouse line with a missense Slc12a1 mutation exhibits most of the features of type I Bartter syndrome and may represent a new model for the study of this human disease.

• Microphthalmia, parkinsonism, and enhanced nociception in Pitx3 ( 416insG ) mice.

  Authors: Michael Rosemann, Alesia Ivashkevich, Jack Favor, Claudia Dalke, Sabine M Hölter, Lore Becker, Ildikó Rácz, Ines Bolle, Martina Klempt, Birgit Rathkolb [......] Thomas Klopstock, Martin Klingenspor, Markus Ollert, Eckhard Wolf, Wolfgang Wurst, Andreas Zimmer, Martin Hrabé de Angelis, Michael Atkinson, Ulrich Heinzmann, Jochen Graw

  Mammalian genome : official journal of the International Mammalian Genome Society. 02/2010; 21(1-2):13-27.

  A new spontaneous mouse mutant was characterized by closed eyelids at weaning and without apparent eyes (provisional gene name, eyeless; provisional gene symbol, eyl). The mutation follows aA new spontaneous mouse mutant was characterized by closed eyelids at weaning and without apparent eyes (provisional gene name, eyeless; provisional gene symbol, eyl). The mutation follows a recessive pattern of inheritance and was mapped to the region of chromosome 19 containing Pitx3. Genetic complementation tests using Pitx3 ( ak/+ ) mice confirmed eyl as a new allele of Pitx3 (Pitx3 ( eyl )). Sequencing of the Pitx3 gene in eyl mutants identified an inserted G after cDNA position 416 (416insG; exon 4). The shifted open reading frame is predicted to result in a hybrid protein still containing the Pitx3 homeobox, but followed by 121 new amino acids. The novel Pitx3 ( eyl/eyl ) mutants expressed ophthalmological and brain defects similar to Pitx3 ( ak/ak ) mice: microphthalmia or anophthalmia and loss of dopamine neurons of the substantia nigra. In addition, we observed in the homozygous eyeless mutants increased extramedullary hematopoiesis in the spleen, frequently liver steatosis, and reduced body weight. There were also several behavioral changes in the homozygous mutants, including reduced forelimb grip strength and increased nociception. In addition to these alterations in both sexes, we observed in female Pitx3 ( eyl/eyl ) mice increased anxiety-related behavior, reduced locomotor activity, reduced object exploration, and increased social contacts; however, we observed decreased anxiety-related behavior and increased arousal in males. Most of these defects identified in the new Pitx3 mutation are observed in Parkinson patients, making the Pitx3 ( eyl ) mutant a valuable new model. It is the first mouse mutant carrying a point mutation within the coding region of Pitx3.

• Post-stroke inhibition of induced NADPH oxidase type 4 prevents oxidative stress and neurodegeneration.

  Authors: Christoph Kleinschnitz, Henrike Grund, Kirstin Wingler, Melanie E Armitage, Emma Jones, Manish Mittal, David Barit, Tobias Schwarz, Christian Geis, Peter Kraft [......] Anja Schrewe, Lore Becker, Valérie Gailus-Durner, Helmut Fuchs, Thomas Klopstock, Martin Hrabé de Angelis, Karin Jandeleit-Dahm, Ajay M Shah, Norbert Weissmann, Harald H H W Schmidt

  PLoS biology. 01/2010; 8(9).

  Ischemic stroke is the second leading cause of death worldwide. Only one moderately effective therapy exists, albeit with contraindications that exclude 90% of the patients. This medical needIschemic stroke is the second leading cause of death worldwide. Only one moderately effective therapy exists, albeit with contraindications that exclude 90% of the patients. This medical need contrasts with a high failure rate of more than 1,000 pre-clinical drug candidates for stroke therapies. Thus, there is a need for translatable mechanisms of neuroprotection and more rigid thresholds of relevance in pre-clinical stroke models. One such candidate mechanism is oxidative stress. However, antioxidant approaches have failed in clinical trials, and the significant sources of oxidative stress in stroke are unknown. We here identify NADPH oxidase type 4 (NOX4) as a major source of oxidative stress and an effective therapeutic target in acute stroke. Upon ischemia, NOX4 was induced in human and mouse brain. Mice deficient in NOX4 (Nox4(-/-)) of either sex, but not those deficient for NOX1 or NOX2, were largely protected from oxidative stress, blood-brain-barrier leakage, and neuronal apoptosis, after both transient and permanent cerebral ischemia. This effect was independent of age, as elderly mice were equally protected. Restoration of oxidative stress reversed the stroke-protective phenotype in Nox4(-/-) mice. Application of the only validated low-molecular-weight pharmacological NADPH oxidase inhibitor, VAS2870, several hours after ischemia was as protective as deleting NOX4. The extent of neuroprotection was exceptional, resulting in significantly improved long-term neurological functions and reduced mortality. NOX4 therefore represents a major source of oxidative stress and novel class of drug target for stroke therapy.

• Loss of the actin remodeler Eps8 causes intestinal defects and improved metabolic status in mice.

  Authors: Arianna Tocchetti, Charlotte Blanche Ekalle Soppo, Fabio Zani, Fabrizio Bianchi, Maria Cristina Gagliani, Benedetta Pozzi, Jan Rozman, Ralf Elvert, Nicole Ehrhardt, Birgit Rathkolb [......] Valérie Gailus-Durner, Johannes Beckers, Martin Klingenspor, Eckhard Wolf, Martin Hrabé de Angelis, Eugenio Scanziani, Carlo Tacchetti, Giorgio Scita, Pier Paolo Di Fiore, Nina Offenhäuser

  PloS one. 01/2010; 5(3):e9468.

  In a variety of organisms, including mammals, caloric restriction improves metabolic status and lowers the incidence of chronic-degenerative diseases, ultimately leading to increased lifespan. HereIn a variety of organisms, including mammals, caloric restriction improves metabolic status and lowers the incidence of chronic-degenerative diseases, ultimately leading to increased lifespan. Here we show that knockout mice for Eps8, a regulator of actin dynamics, display reduced body weight, partial resistance to age- or diet-induced obesity, and overall improved metabolic status. Alteration in the liver gene expression profile, in behavior and metabolism point to a calorie restriction-like phenotype in Eps8 knockout mice. Additionally, and consistent with a calorie restricted metabolism, Eps8 knockout mice show increased lifespan. The metabolic alterations in Eps8 knockout mice correlated with a significant reduction in intestinal fat absorption presumably caused by a 25% reduction in intestinal microvilli length. Our findings implicate actin dynamics as a novel variable in the determination of longevity. Additionally, our observations suggest that subtle differences in energy balance can, over time, significantly affect bodyweight and metabolic status in mice.

• Novel Missense Mutation of Uromodulin in Mice Causes Renal Dysfunction with Alterations in Urea Handling, Energy and Bone Metabolism.

  Authors: Elisabeth Kemter, Birgit Rathkolb, Jan Rozman, Wolfgang Hans, Anja Schrewe, Christina Landbrecht, Matthias Klaften, Boris T Ivandic, Helmut Fuchs, Valerie Gailus-Durner, Martin Klingenspor, Martin Hrabe de Angelis, Eckhard Wolf, Ruediger Wanke, Bernhard Aigner

  American journal of physiology. Renal physiology. 09/2009;

  Uromodulin-associated kidney disease is a heritable renal disease in humans caused by mutations in the uromodulin (UMOD) gene. The pathogenesis of the disease is mostly unknown. In this study, weUromodulin-associated kidney disease is a heritable renal disease in humans caused by mutations in the uromodulin (UMOD) gene. The pathogenesis of the disease is mostly unknown. In this study, we describe a novel chemically induced mutant mouse line termed Umod(A227T) exhibiting impaired renal function. The A227T amino acid exchange may impair uromodulin trafficking, leading to dysfunction of thick ascending limb cells of Henle's loop of the kidney. As a consequence, homozygous mutant mice display azotemia, impaired urine concentration ability, reduced fractional excretion of uric acid and a selective defect to concentrate urea. Osteopenia in mutant mice is presumably a result of chronic hypercalciuria. In addition, body composition, lipid and energy metabolism are indirectly affected in heterozygous and homozygous mutant Umod(A227T) mice, manifesting in reduced body weight, fat mass and metabolic rate as well as reduced blood cholesterol, triglycerides, and non-esterified fatty acids. In conclusion, Umod(A227T) might act as gain-of-toxic-function mutation. Therefore, the Umod(A227T) mouse line provides novel insights into consequences of disturbed uromodulin excretion regarding renal dysfunction as well as bone, energy and lipid metabolism. Key words: N-ethyl-N-nitrosourea, kidney, renal disease, Umod.

• Neuronal 3',3,5-triiodothyronine (T3) uptake and behavioral phenotype of mice deficient in Mct8, the neuronal T3 transporter mutated in Allan-Herndon-Dudley syndrome.

  Authors: Eva K Wirth, Stephan Roth, Cristiane Blechschmidt, Sabine M Hölter, Lore Becker, Ildiko Racz, Andreas Zimmer, Thomas Klopstock, Valerie Gailus-Durner, Helmut Fuchs, Wolfgang Wurst, Thomas Naumann, Anja Bräuer, Martin Hrabé de Angelis, Josef Köhrle, Annette Grüters, Ulrich Schweizer

  The Journal of neuroscience : the official journal of the Society for Neuroscience. 08/2009; 29(30):9439-49.

  Thyroid hormone transport into cells requires plasma membrane transport proteins. Mutations in one of these, monocarboxylate transporter 8 (MCT8), have been identified as underlying cause for theThyroid hormone transport into cells requires plasma membrane transport proteins. Mutations in one of these, monocarboxylate transporter 8 (MCT8), have been identified as underlying cause for the Allan-Herndon-Dudley syndrome, an X-linked mental retardation in which the patients also present with abnormally high 3',3,5-triiodothyronine (T(3)) plasma levels. Mice deficient in Mct8 replicate the thyroid hormone abnormalities observed in the human condition. However, no neurological deficits have been described in mice lacking Mct8. Therefore, we subjected Mct8-deficient mice to a comprehensive immunohistochemical, neurological, and behavioral screen. Several behavioral abnormalities were found in the mutants. Interestingly, some of these behavioral changes are compatible with hypothyroidism, whereas others rather indicate hyperthyroidism. We thus hypothesized that neurons exclusively dependent on Mct8 are in a hypothyroid state, whereas neurons expressing other T(3) transporters become hyperthyroid, if they are exposed directly to the high plasma T(3). The majority of T(3) uptake in primary cortical neurons is mediated by Mct8, but pharmacological inhibition suggested functional expression of additional T(3) transporter classes. mRNAs encoding six T(3) transporters, including L-type amino acid transporters (LATs), were coexpressed with Mct8 in isolated neurons. We then demonstrated Lat2 expression in cultured neurons and throughout murine brain development. In contrast, LAT2 is expressed in microglia in the developing human brain during gestation, but not in neurons. We suggest that lack of functional complementation by alternative thyroid hormone transporters in developing human neurons precipitates the devastating neurodevelopmental phenotype in MCT8-deficient patients, whereas Mct8-deficient mouse neurons are functionally complemented by other transporters, for possibly Lat2.