The Biochemical and Genetic Odyssey to the Function of a Nicastrin-Like Protein

gamma-Secretase is a high-molecular-weight protein complex required for the proteolytic processing of various transmembrane proteins including the Alzheimer's disease-associated amyloid precursor protein and the signaling receptor Notch. One of the gamma-secretase complex components is the type I transmembrane protein nicastrin. Here we review the odyssey to a cyclopic fish, which at the end allowed the functional analysis of nicalin, a novel member of the nicastrin protein family. This 60-kDa protein is part of a previously unknown membrane protein complex unrelated to gamma-secretase and binds to Nomo (Nodal modulator, previously known as pM5), a novel 130-kDa transmembrane protein. Both proteins are highly conserved in metazoans and show almost identical tissue distribution in humans. Functional studies in zebrafish embryos and cultured human cells revealed that nicalin and Nomo collaborate to antagonize the Nodal/TGF beta signaling pathway. Thus, nicastrin and nicalin are both associated with protein complexes involved in cell fate decisions during early embryonic development. Copyright (C) 2004 S. Karger AG, Base

Cellular functions of gamma-secretase-related proteins

Amyloid-beta pepticle (A beta) is generated by gamma-secretase, a membrane protein complex with an unusual aspartyl protease activity consisting of the four components presenilin, nicastrin, APH-1 and PEN-2. Presenilin is considered the catalytic subunit of this complex since it represents the prototype of the new family of intramembrane-cleaving GxGD-type aspartyl proteases. Recently, five novel members of this family and a nicastrin-like protein were identified. Whereas one of the GxGD-type proteins was shown to be identical with signal pepticle peptidase (SPP), the function of the others, now called SPP-like proteins (SPPLs), is not known. We therefore analyzed SPPL2b and SPPL3 and demonstrated that they localize to different subcellular compartments suggesting nonredundant functions. This was supported by different phenotypes obtained in knockdown studies in zebrafish embryos. In addition, these phenotypes could be phenocopied by ectopic expression of putative active site mutants, providing strong evidence for a proteolytic function of SPPL2b and SPPL3. We also identified and characterized the nicastrin-like protein nicalin which, together with the 130-kDa protein NOMO (Nodal modulator), forms a membrane protein complex different from gamma-secretase. We found that during zebrafish embryogenesis this complex is involved in the patterning of the axial mesendoderm, a process controlled by the Nodal signaling pathway. Copyright (c) 2006 S. Karger AG, Basel

Transgenic Zebrafish as a Novel Animal Model to Study Tauopathies and Other Neurodegenerative Disorders in vivo

Our ageing society is confronted with a dramatic increase in patients suffering from tauopathies such as Alzheimer's disease, frontotemporal dementia and others. Typical neuropathological lesions including tangles composed of hyper-phosphorylated tau protein as well as severe neuronal cell death characterize these disorders. No mechanism-based cures are available at present. Genetically modified animals are invaluable models to understand the molecular disease mechanisms and to screen for modifying compounds. We recently introduced tau-transgenic zebrafish as a novel model for tauopathies. Our model allows recapitulating key pathological features of tauopathies within an extremely short time. Moreover, life imaging of tau-dependent neuronal cell death was performed for the very first time. This demonstrated tau-dependent neuronal cell loss independent of tangle formation. Finally, we exemplified that the zebrafish frontotemporal dementia model can be used to screen for drugs that prevent abnormal tau phosphorylation and neuronal cell death. Copyright (C) 2010 S. Karger AG, Base

Granulin Knock Out Zebrafish Lack Frontotemporal Lobar Degeneration and Neuronal Ceroid Lipofuscinosis Pathology

Loss of function mutations in granulin (GRN) are linked to two distinct neurological disorders, frontotemporal lobar degeneration (FTLD) and neuronal ceroid lipofuscinosis (NCL). It is so far unknown how a complete loss of GRN in NCL and partial loss of GRN in FTLD can result in such distinct diseases. In zebrafish, there are two GRN homologues, Granulin A (Grna) and Granulin B (Grnb). We have generated stable Grna and Grnb loss of function zebrafish mutants by zinc finger nuclease mediated genome editing. Surprisingly, the grna and grnb single and double mutants display neither spinal motor neuron axonopathies nor a reduced number of myogenic progenitor cells as previously reported for Grna and Grnb knock down embryos. Additionally, grna-/-;grnb-/- double mutants have no obvious FTLD- and NCL-related biochemical and neuropathological phenotypes. Taken together, the Grna and Grnb single and double knock out zebrafish lack any obvious morphological, pathological and biochemical phenotypes. Loss of zebrafish Grna and Grnb might therefore either be fully compensated or only become symptomatic upon additional challenge

A Premium on Good Judgment

This is an institution with a great tradition, and I am honored to have been asked to address you on this day—an honor made all the greater given the distinguished individuals who preceded me in years past. I will be characteristically blunt: you are departing the War College at a time of considerable international turmoil. Ours is a time of war, or to be more precise, wars—a global war on terrorism, a war in Afghanistan, and a war in Iraq, not to mention a conflict in Colombia and conflicts in several countries in Africa. Those who predicted that the world after the end of the Cold War would be tranquil were wrong, or at least premature. One result is that military force, par- ticularly American military force, remains relevant, and then some

Utilizing Campbell\u27s Listening Models in the Elementary Music Room

Patricia Shehan Campbell work revolves around her created Listening Models to teach World Music to students of all ages utilizing a culturally accurate method. As a result, from her research, this study asks do Campbell’s Listening Models help students retain cultural and musical information on a music culture, specifically the Eastern Shoshone. Although example lessons exist in Campbell’s works as well as the Smithsonian Folkways website, research on the effectiveness is lacking. In order to test the effectiveness, this study offers a set of lessons based on the Eastern Shoshone for fourth and fifth grade students and tracks their learning through a pretest and posttest, individual student interviews, and whole class observations. Data from the pretest and posttest show students demonstrated a higher understanding after being taught the lessons. The results show that Campbell’s Listening Models are an effective tool music educators can employ to teach a more culturally responsible lesson

Multilaterale Friedenssicherung in Afrika

Der Sicherheitsrat der Vereinten Nationen (VN) mandatierte 2013 zwei neue multilaterale Friedenseinsätze in afrikanischen Staaten: Im Juli begann die Mission in Mali, um das vorläufige Friedensabkommen umzusetzen und Wahlen zu sichern. Seit September operiert erstmals eine VN-Interventionsbrigade als Teil der schon bestehenden Mission in der Demokratischen Republik Kongo (DR Kongo), die auch gegen Rebellengruppen im Osten des Landes kämpfen soll. Die vor allem von afrikanischen Staaten getragenen Einsätze in Mali und der DR Kongo verdeutlichen zwei Trends der multilateralen Friedenssicherung: Erstens haben sich unbewaffnete Beobachtermissionen zu multidimensionalen Einsätzen gewandelt, die neben der Überwachung von Waffenstillständen auch die institutionellen Grundlagen für einen langfristigen Frieden sichern sollen. Zweitens übernehmen afrikanische Staaten inzwischen eine immer größere Rolle bei der Bereitstellung von Truppen für Friedenseinsätze in Afrika. Die politikwissenschaftliche Forschung zeigt, dass besonders robust mandatierte, komplexe Friedensoperationen mit ausreichender Truppenstärke zu einem Frieden nach Bürgerkriegen beitragen können. Daher ist das gestiegene Engagement afrikanischer Staaten bei der Friedenssicherung grundsätzlich begrüßenswert, denn ein stärkeres westliches Engagement in Form von Truppen für Friedensmissionen in afrikanischen Konflikten erscheint in absehbarer Zukunft nicht realistisch. Die gestiegene Einsatzbereitschaft afrikanischer Staaten ist Teil des Aufbaus einer "afrikanischen Friedens- und Sicherheitsarchitektur" seitens der Afrikanischen Union (African Union, AU). Politische Konflikte ihrer Mitgliedsstaaten, mangelnde Ressourcenausstattung und fehlende Finanzmittel erschweren allerdings nach wie vor genuin "afrikanische Lösungen für afrikanische Probleme". Eine politische, finanzielle sowie technische Stärkung dieser regionalen Sicherheitsarchitektur ist notwendig, um die friedensfördernden Effekte von Friedensoperationen weiter zu verbessern und ihre negativen gesellschaftlichen Auswirkungen zu verringern

The Nicastrin ectodomain adopts a highly thermostable structure

Nicastrin is a type I transmembrane glycoprotein, which is part of the high molecular weight gamma-secretase complex. gamma-Secretase is one of the key players associated with the generation of Alzheimer's disease pathology, since it liberates the neurotoxic amyloid beta-peptide. Four proteins Nicastrin, anterior pharynx-defective-1 (Aph-1), presenilin enhancer-2 (Pen-2) and Presenilin are essential to form the active gamma-secretase complex. Recently it has been shown, that Nicastrin has a key function in stabilizing the mature gamma-secretase complex and may also be involved in substrate recognition. So far no structural data for the Nicastrin ectodomain or any other gamma-secretase component are available. We therefore used Circular Dichroism (CD) spectroscopy to demonstrate that Nicastrin, similar to its homologues, the Streptomyces griseus aminopeptidase (SGAP) and the transferrin receptor (TfR), adopts a thermostable secondary structure. Furthermore, the Nicastrin ectodomain has an exceptionally high propensity to refold after thermal denaturation. These findings provide evidence to further support the hypothesis that Nicastrin may share evolutionary conserved properties with the aminopeptidase and the transferrin receptor family