TY  - THES
A1  - Friedrich, Maximilian Uwe
T1  - Funktionelle Charakterisierung einer Tripletdeletion in SLC5A4 (SGLT3) als Kandidatengen für das Aufmerksamkeitsdefizit-/ Hyperaktivitätssyndrom (ADHS)
T1  - Functional characterization of a triplet deletion in the attention-deficit/hyperactivity (ADHD) candidate gene SLC5A4 (SGLT3)
N2  - Natrium-Glukose Transporter (SGLT) gehören zur „solute carrier 5“ (SLC5) Familie, die sich durch einen sekundär aktiven, natriumabhängigen Transport von Zuckern und an-deren Molekülen nach intrazellulär auszeichnen. Die durch das Gen SLC5A4 kodierte Isoform SGLT3 transportiert dagegen keinen Zucker, sondern verhält sich als Glukosesensor, der nach Bindung seiner Liganden eine Membrandepolarisation induziert. In genomweiten Exomsequenzierungsstudien (whole exome sequencing, WES) mehrerer erweiterter Stammbäume mit hoher Prävalenz des Aufmerksamkeitsdefizit-/Hyperaktivitätssyndroms (ADHS) wurde im Vorfeld eine ATG-Tripletdeletion in SLC5A4 identifiziert, die zum Verlust einer Aminosäure (ΔM500) in SGLT3 führt und zumindest partiell mit dem klinischen Phänotyp kosegregiert.
In der vorliegenden Arbeit wurde die zentralnervöse Expression von SGLT3 auf RNA- Ebene mittels Reverse-Transkriptase PCR sowie real-time PCR aus humanen Gesamt-RNAs nachgewiesen. Dabei konnte eine ubiquitäre Expression im Gehirn mit relativ erhöhter Expression unter anderem in Striatum und Hypothalamus, deren Dysfunktion in der Pathogenese des ADHS impliziert wurde, gezeigt werden. Da Mutationen in homologen Domänen der eng strukturverwandten Isoformen SGLT1 und SGLT2 sowohl intestinale als auch renale Funktionen schwer beeinträchtigen, wurden in dieser Arbeit funktionelle Charakteristika sowohl des wildtypischen als auch der ΔM500 und der benachbarten ΔI501 Deletionsvariante von SGLT3 mittels Zwei-Elektroden Spannungs- und Stromklemme in entsprechend cRNA-injizierten Xenopus laevis Oozyten untersucht. Der hochpotente SGLT3-spezifische Iminozuckeragonist 1-Desoxynojirimycin (DNJ) induzierte an SGLT3-exprimierenden Oozyten in sauren Bedingungen etwa dreifach größere Kationeneinströme als D-Glukose, was sowohl im Spannungsklemmen-, und anhand einer entsprechenden Membrandepolarisation im Stromklemmenmodus gezeigt wurde. Die mit der ΔM500 bzw. ΔI501 Variante injizierten Oozyten dagegen zeigten in den maximalen Aktivierungsbedingungen um 92% bzw. 96% (p<0,01) reduzierte Kationeneinströme, sodass diese als hochgradig schädliche „Loss of Function“ Mutationen in SGLT3 charakterisiert wurden. Dieser Befund wurde mittels bioinformatischer in-silico Effektvorhersage validiert.
Um Konsequenzen der Sequenzalteration auf den Membraneinbau der Transporter zu untersuchen, wurden die mit einem gelb fluoreszierenden Farbstoff (YFP) markierten Transporter in Oozytenmembranen mittels Laser-Scanning Mikroskop nachgewiesen und die jeweiligen Mengen der Konstrukte anhand der Fluoreszenzintensitäten quantifiziert. Dabei zeigte sich eine um 53% bzw. 42% (p<0,01) reduzierte Menge der mutierten Konstrukte ΔM500 bzw. ΔI501 in der Membran, was zusätzliche schädliche Effekte der Mutationen auf das sogenannte Membrantargeting der Transporter belegt.
Zusammenfassend demonstrieren die Ergebnisse dieser Arbeit, dass die ΔM500 Variante von SGLT3, welcher in ADHS-relevanten Hirnarealen exprimiert wird, dessen sub-stratinduzierte Natriumleitfähigkeit aufhebt und den Membraneinbau beeinträchtigen könnte, was in Wechselwirkung mit anderen genetischen ADHS Risikovarianten das Risiko für ADHS in Mutationsträgern beeinflussen kann.
N2  - Sodium-glucose transporters (SGLT) belong to the solute carrier 5 family, which is characterized by secondary active sodium dependent transport of sugars and other solutes. In contrast, SGLT3, encoded by the SLC5A4 gene, does not transport sugar but acts as a glucose sensor, inducing membrane depolarization upon ligand binding. In whole exome sequencing studies of several extended pedigrees with high density of attention-deficit/hyperactivity disorder (ADHD), an ATG triplet deletion of SLC5A4, leading to a single amino acid loss (ΔM500) in SGLT3, was found to cosegregate, although imper-fectly, with the clinical phenotype.
In this work, expression of SGLT3 on RNA level was proven ubiquiteously in the human brain with relatively increased expression levels in striatum and hypothalamus, which had repeatedly been implicated in ADHD pathophysiology. Since mutations in homolo-gous domains of the structurally closely related isoforms SGLT1 and SGLT2 can signif-icantly impair intestinal and renal function, functional properties of wildtype, ΔM500 and neighboring ΔI501 deletion variants of SGLT3 were investigated by voltage clamp and current clamp recordings in cRNA-injected Xenopus laevis oocytes. The SGLT3-specific iminosugar agonist 1-Desoxynojirimycin (DNJ) induced a threefold increase of cation influx compared to the classic SGLT substrate D-glucose alone as revealed by robust inward currents in voltage clamp and cell depolarization in current clamp modes. ΔM500-SGLT3 and ΔI501-SGLT3 injected oocytes showed cationic inward currents significantly reduced by 92% and 96% (p<0,01) respectively. In-silico modelling predicted deleterious functional effects of both mutations, thus validating these results.
To investigate possible effects of these sequence alterations on membrane targeting of the transporters, fusion constructs with YFP were generated and intensity of membrane fluorescence was quantified by confocal laser scanning microscopy. In comparison to wildtype SGLT3, fluorescence signals of ΔM500 and ΔI501 injected oocytes were de-creased by 53% and 42% (p<0,01) respectively.
Taken together, the results of this work suggest that the ΔM500 mutant of SGLT3, which is expressed in ADHS-implicated brain tissues completely abolishes its ligand dependent sodium conductance and may impair its membrane targeting, which, in interaction with other genetic ADHD risk variants, may confer a risk for ADHD in deletion carriers.
KW  - ADHS
KW  - Genetik
KW  - Membrantransporter
KW  - SGLT
KW  - Glukosemetabolismus
KW  - ADHD
KW  - Genetics
KW  - Membrane transporters
KW  - Glucose metabolism
Y1  - 2019
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-184791
ER  - 
TY  - JOUR
A1  - El-Helou, Sabine M.
A1  - Biegner, Anika-Kerstin
A1  - Bode, Sebastian
A1  - Ehl, Stephan R.
A1  - Heeg, Maximilian
A1  - Maccari, Maria E.
A1  - Ritterbusch, Henrike
A1  - Speckmann, Carsten
A1  - Rusch, Stephan
A1  - Scheible, Raphael
A1  - Warnatz, Klaus
A1  - Atschekzei, Faranaz
A1  - Beider, Renata
A1  - Ernst, Diana
A1  - Gerschmann, Stev
A1  - Jablonka, Alexandra
A1  - Mielke, Gudrun
A1  - Schmidt, Reinhold E.
A1  - Schürmann, Gesine
A1  - Sogkas, Georgios
A1  - Baumann, Ulrich H.
A1  - Klemann, Christian
A1  - Viemann, Dorothee
A1  - Bernuth, Horst von
A1  - Krüger, Renate
A1  - Hanitsch, Leif G.
A1  - Scheibenbogen, Carmen M.
A1  - Wittke, Kirsten
A1  - Albert, Michael H.
A1  - Eichinger, Anna
A1  - Hauck, Fabian
A1  - Klein, Christoph
A1  - Rack-Hoch, Anita
A1  - Sollinger, Franz M.
A1  - Avila, Anne
A1  - Borte, Michael
A1  - Borte, Stephan
A1  - Fasshauer, Maria
A1  - Hauenherm, Anja
A1  - Kellner, Nils
A1  - Müller, Anna H.
A1  - Ülzen, Anett
A1  - Bader, Peter
A1  - Bakhtiar, Shahrzad
A1  - Lee, Jae-Yun
A1  - Heß, Ursula
A1  - Schubert, Ralf
A1  - Wölke, Sandra
A1  - Zielen, Stefan
A1  - Ghosh, Sujal
A1  - Laws, Hans-Juergen
A1  - Neubert, Jennifer
A1  - Oommen, Prasad T.
A1  - Hönig, Manfred
A1  - Schulz, Ansgar
A1  - Steinmann, Sandra
A1  - Klaus, Schwarz
A1  - Dückers, Gregor
A1  - Lamers, Beate
A1  - Langemeyer, Vanessa
A1  - Niehues, Tim
A1  - Shai, Sonu
A1  - Graf, Dagmar
A1  - Müglich, Carmen
A1  - Schmalzing, Marc T.
A1  - Schwaneck, Eva C.
A1  - Tony, Hans-Peter
A1  - Dirks, Johannes
A1  - Haase, Gabriele
A1  - Liese, Johannes G.
A1  - Morbach, Henner
A1  - Foell, Dirk
A1  - Hellige, Antje
A1  - Wittkowski, Helmut
A1  - Masjosthusmann, Katja
A1  - Mohr, Michael
A1  - Geberzahn, Linda
A1  - Hedrich, Christian M.
A1  - Müller, Christiane
A1  - Rösen-Wolff, Angela
A1  - Roesler, Joachim
A1  - Zimmermann, Antje
A1  - Behrends, Uta
A1  - Rieber, Nikolaus
A1  - Schauer, Uwe
A1  - Handgretinger, Rupert
A1  - Holzer, Ursula
A1  - Henes, Jörg
A1  - Kanz, Lothar
A1  - Boesecke, Christoph
A1  - Rockstroh, Jürgen K.
A1  - Schwarze-Zander, Carolynne
A1  - Wasmuth, Jan-Christian
A1  - Dilloo, Dagmar
A1  - Hülsmann, Brigitte
A1  - Schönberger, Stefan
A1  - Schreiber, Stefan
A1  - Zeuner, Rainald
A1  - Ankermann, Tobias
A1  - Bismarck, Philipp von
A1  - Huppertz, Hans-Iko
A1  - Kaiser-Labusch, Petra
A1  - Greil, Johann
A1  - Jakoby, Donate
A1  - Kulozik, Andreas E.
A1  - Metzler, Markus
A1  - Naumann-Bartsch, Nora
A1  - Sobik, Bettina
A1  - Graf, Norbert
A1  - Heine, Sabine
A1  - Kobbe, Robin
A1  - Lehmberg, Kai
A1  - Müller, Ingo
A1  - Herrmann, Friedrich
A1  - Horneff, Gerd
A1  - Klein, Ariane
A1  - Peitz, Joachim
A1  - Schmidt, Nadine
A1  - Bielack, Stefan
A1  - Groß-Wieltsch, Ute
A1  - Classen, Carl F.
A1  - Klasen, Jessica
A1  - Deutz, Peter
A1  - Kamitz, Dirk
A1  - Lassy, Lisa
A1  - Tenbrock, Klaus
A1  - Wagner, Norbert
A1  - Bernbeck, Benedikt
A1  - Brummel, Bastian
A1  - Lara-Villacanas, Eusebia
A1  - Münstermann, Esther
A1  - Schneider, Dominik T.
A1  - Tietsch, Nadine
A1  - Westkemper, Marco
A1  - Weiß, Michael
A1  - Kramm, Christof
A1  - Kühnle, Ingrid
A1  - Kullmann, Silke
A1  - Girschick, Hermann
A1  - Specker, Christof
A1  - Vinnemeier-Laubenthal, Elisabeth
A1  - Haenicke, Henriette
A1  - Schulz, Claudia
A1  - Schweigerer, Lothar
A1  - Müller, Thomas G.
A1  - Stiefel, Martina
A1  - Belohradsky, Bernd H.
A1  - Soetedjo, Veronika
A1  - Kindle, Gerhard
A1  - Grimbacher, Bodo
T1  - The German national registry of primary immunodeficiencies (2012-2017)
JF  - Frontiers in Immunology
N2  - Introduction: The German PID-NET registry was founded in 2009, serving as the first national registry of patients with primary immunodeficiencies (PID) in Germany. It is part of the European Society for Immunodeficiencies (ESID) registry. The primary purpose of the registry is to gather data on the epidemiology, diagnostic delay, diagnosis, and treatment of PIDs. 

Methods: Clinical and laboratory data was collected from 2,453 patients from 36 German PID centres in an online registry. Data was analysed with the software Stata® and Excel. 

Results: The minimum prevalence of PID in Germany is 2.72 per 100,000 inhabitants. Among patients aged 1-25, there was a clear predominance of males. The median age of living patients ranged between 7 and 40 years, depending on the respective PID. Predominantly antibody disorders were the most prevalent group with 57% of all 2,453 PID patients (including 728 CVID patients). A gene defect was identified in 36% of patients. Familial cases were observed in 21% of patients. The age of onset for presenting symptoms ranged from birth to late adulthood (range 0-88 years). Presenting symptoms comprised infections (74%) and immune dysregulation (22%). Ninety-three patients were diagnosed without prior clinical symptoms. Regarding the general and clinical diagnostic delay, no PID had undergone a slight decrease within the last decade. However, both, SCID and hyper IgE-syndrome showed a substantial improvement in shortening the time between onset of symptoms and genetic diagnosis. Regarding treatment, 49% of all patients received immunoglobulin G (IgG) substitution (70%-subcutaneous; 29%-intravenous; 1%-unknown). Three-hundred patients underwent at least one hematopoietic stem cell transplantation (HSCT). Five patients had gene therapy. 

Conclusion: The German PID-NET registry is a precious tool for physicians, researchers, the pharmaceutical industry, politicians, and ultimately the patients, for whom the outcomes will eventually lead to a more timely diagnosis and better treatment.
KW  - registry for primary immunodeficiency
KW  - primary immunodeficiency (PID)
KW  - German PID-NET registry
KW  - PID prevalence
KW  - European Society for Immunodeficiencies (ESID)
KW  - IgG substitution therapy
KW  - CVID
Y1  - 2019
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-226629
VL  - 10
ER  -