Vanessa Suckow

Publications of Vanessa Suckow

• GPR30 estrogen receptor agonists induce mechanical hyperalgesia in the rat.

  Authors: Julia Kuhn, Olayinka A Dina, Chandan Goswami, Vanessa Suckow, Jon D Levine, Tim Hucho

  The European journal of neuroscience. 05/2008; 27(7):1700-9.

  We evaluated the signalling pathway by which estrogen acts in peripheral tissue to produce protein kinase Cepsilon (PKCepsilon)-dependent mechanical hyperalgesia. Specific agonists for the classicalWe evaluated the signalling pathway by which estrogen acts in peripheral tissue to produce protein kinase Cepsilon (PKCepsilon)-dependent mechanical hyperalgesia. Specific agonists for the classical estrogen receptors (ER), ERalpha and ERbeta, did not result in activation of PKCepsilon in neurons of dissociated rat dorsal root ganglia. In contrast, G-1, a specific agonist of the recently identified G-protein-coupled estrogen receptor, GPR30, induced PKCepsilon translocation. Involvement of GPR30 and independence of ERalpha and ERbeta was confirmed using the GPR30 agonist and simultaneous ERalpha and ERbeta antagonist ICI 182,780 (fulvestrant). The GPR30 transcript could be amplified from dorsal root ganglia tissue. We found estrogen-induced as well as GPR30-agonist-induced PKCepsilon translocation to be restricted to the subgroup of nociceptive neurons positive for isolectin IB4 from Bandeiraea simplicifolia. Corroborating the cellular results, both GPR30 agonists, G-1 as well as ICI 182,780, resulted in the onset of PKCepsilon-dependent mechanical hyperalgesia if injected into paws of adult rats. We therefore suggest that estrogen acts acutely at GPR30 in nociceptors to produce mechanical hyperalgesia.

• Mild phenotypes in a series of patients with Opitz GBBB syndrome with MID1 mutations.

  Authors: Joyce So, Vanessa Suckow, Zofia Kijas, Vera Kalscheuer, Bettina Moser, Jennifer Winter, Marieke Baars, Helen Firth, Peter Lunt, Ben Hamel [......] Beate Albrecht, Gabriele Gillessen-Kaesbach, Ineke van der Burgt, Fred Petrij, Laurence Faivre, Julie McGaughran, Fiona McKenzie, John M Opitz, Timothy Cox, Susann Schweiger

  American journal of medical genetics. Part A. 02/2005; 132A(1):1-7.

  Opitz syndrome (OS; MIM 145410 and MIM 300000) is a congenital midline malformation syndrome characterized by hypertelorism, hypospadias, cleft lip/palate, laryngotracheoesophageal (LTE)Opitz syndrome (OS; MIM 145410 and MIM 300000) is a congenital midline malformation syndrome characterized by hypertelorism, hypospadias, cleft lip/palate, laryngotracheoesophageal (LTE) abnormalities, imperforate anus, developmental delay, and cardiac defects. The X-linked form (XLOS) is caused by mutations in the MID1 gene, which encodes a microtubule-associated RBCC protein. In this study, phenotypic manifestations of patients with and without MID1 mutations were compared to determine genotype-phenotype correlations. We detected 10 novel mutations, 5 in familial cases, 2 in sporadic cases, and 3 in families for whom it was not clear if they were familial or sporadic. The genotype and phenotype was compared for these 10 families, clinically diagnosed OS patients found not to have MID1 mutations, and 4 families in whom we have previously reported MID1 mutations. This combined data set includes clinical and mutation data on 70 patients. The XLOS patients with MID1 mutations were less severely affected than patients with MID1 mutations reported in previous studies, particularly in functionally significant neurologic, LTE, anal, and cardiac abnormalities. Minor anomalies were more prevalent in patients with MID1 mutations compared to those without mutations in this study. Female MID1 mutation carriers had milder phenotypes compared to male MID1 mutation carriers, with the most common manifestation being hypertelorism in both sexes. Most of the anomalies found in the patients of the present study do not correlate with the MID1 mutation type, with the possible exception of LTE malformations. This study demonstrates the wide spectrum of severity and manifestations of OS. It also shows that XLOS patients with MID1 mutations may be less severely affected than indicated in prior reports.

• Regulation of the MID1 protein function is fine-tuned by a complex pattern of alternative splicing.

  Authors: Jennifer Winter, Tanja Lehmann, Sybille Krauss, Alexander Trockenbacher, Zofia Kijas, John Foerster, Vanessa Suckow, Marie-Laure Yaspo, Andreas Kulozik, Vera Kalscheuer, Rainer Schneider, Susann Schweiger

  Human genetics. 06/2004; 114(6):541-52.

  Clinical features of Opitz BBB/G syndrome are confined to defects of the developing ventral midline, whereas the causative gene, MID1, is ubiquitously expressed. Therefore, a non-redundantClinical features of Opitz BBB/G syndrome are confined to defects of the developing ventral midline, whereas the causative gene, MID1, is ubiquitously expressed. Therefore, a non-redundant physiological function of the MID1 product appears to be developmentally restricted. Here, we report the identification of several alternative MID1 exons in human, mouse and fugu. We show that splice variants of the MID1 gene that are comparable in terms of function occur in the three organisms, suggesting an important role in the regulation of the MID1 protein function. Accordingly, we observed differential MID1 transcript patterns in a tissue-specific manner by Northern blot and RT-PCR. The identified splice variants cause loss-of-function effects via several mechanisms. Some introduce a stop codon followed by a novel poly(A(+)) tail, leading to the formation of C-terminally truncated proteins. Dominant negative effects through altered binding to the MID1-interacting protein alpha4 in vitro could be demonstrated in a couple of cases. Others carry premature termination codons without poly(A(+)) tails. These are degraded by nonsense mediated mRNA decay (NMD). Our data reveal a mechanism conserved in human, mouse and fugu that regulates developmentally restricted MID1 activity and suggest NMD to be critical in the translational regulation of a ubiquitously transcribed mRNA.

• NYX (nyctalopin on chromosome X), the gene mutated in congenital stationary night blindness, encodes a cell surface protein.

  Authors: Christina Zeitz, Harry Scherthan, Susanne Freier, Silke Feil, Vanessa Suckow, Susann Schweiger, Wolfgang Berger

  Investigative ophthalmology & visual science. 11/2003; 44(10):4184-91.

  PURPOSE. The complete type of X-linked congenital stationary night blindness (CSNB1) in human and mouse is caused by mutations in the NYX gene. The human NYX protein has been predicted to contain anPURPOSE. The complete type of X-linked congenital stationary night blindness (CSNB1) in human and mouse is caused by mutations in the NYX gene. The human NYX protein has been predicted to contain an N-terminal endoplasmic reticulum (ER) signaling sequence and a C-terminal glycosylphosphatidylinositol (GPI) anchor. In the current study, these computer predictions were verified experimentally by expression of domain-specific cDNA constructs in COS-7 and HeLa cells. Moreover, computer-based analysis of the orthologue mouse amino acid sequence did not reveal a GPI anchor, which may result in a different protein localization compared with human NYX. Therefore, the cellular localization for the mouse Nyx protein was also examined. METHODS. A new method was established that differentially visualizes both the protein at the surface of the living cell and subsequently in intracellular compartments. The localization of the human and mouse V5-tagged wild-type and mutant NYX protein were studied. RESULTS. Human and mouse V5-NYX proteins were dispersed in the form of speckles over the entire cell surface. Subsequent staining of the same cells after detergent extraction revealed that V5-NYX located to the ER and Golgi apparatus. Deletion of the GPI anchor domain of NYX resulted in a time-dependent loss of V5-NYX from the surface of living cells and accumulation of this truncated protein in the ER and Golgi apparatus. Deletion of the ER signal sequence in Nyx delocalized the intracellular V5-Nyx protein and caused its dispersion in the cytosol. Furthermore, mutations introduced in the leucine-rich repeat (LRR)-region, which has been described as a pathogenic variant of NYX, had no effect on subcellular localization of the protein. CONCLUSIONS. These data provide evidence that human and mouse nyctalopin are membrane-bound extracellular proteins and are functionally conserved.

• Duplication of the MID1 first exon in a patient with Opitz G/BBB syndrome.

  Authors: Jennifer Winter, Tanja Lehmann, Vanessa Suckow, Zofia Kijas, Andreas Kulozik, Vera Kalscheuer, Ben Hamel, Koen Devriendt, John Opitz, Steffen Lenzner, Hans-Hilger Ropers, Susann Schweiger

  Human genetics. 04/2003; 112(3):249-54.

  Opitz G/BBB syndrome is a malformation syndrome of the ventral midline mainly characterized by hypertelorism, swallowing difficulties, hypospadias and developmental delay. SSCP analysis and genomicOpitz G/BBB syndrome is a malformation syndrome of the ventral midline mainly characterized by hypertelorism, swallowing difficulties, hypospadias and developmental delay. SSCP analysis and genomic sequencing of the MID1 open reading frame have identified mutations in 80% of the families with X-linked inheritance. However, in many patients the underlying genetic defect remains undetected by these techniques. Using RNA diagnostics we have now identified a duplication of the MID1 first exon in a patient with X-linked Opitz G/BBB syndrome. This duplication introduces a premature termination codon. In addition, we could significantly lower the threshold for mutation detection on the DNA level by combining SSCP analysis with DHPLC technology.

• Elevated levels of Rad51 recombination protein in tumor cells.

  Authors: Elke Raderschall, Karen Stout, Susanne Freier, Vanessa Suckow, Susann Schweiger, Thomas Haaf

  Cancer research. 02/2002; 62(1):219-25.

  Rad51 is the key enzyme for homologous recombination, an evolutionarily conserved mechanism for the repair of DNA damage and the generation of genetic diversity. Given the observation that manyRad51 is the key enzyme for homologous recombination, an evolutionarily conserved mechanism for the repair of DNA damage and the generation of genetic diversity. Given the observation that many tumors become resistant to radiation therapy and DNA-damaging chemotherapeutics and also that tumor cell populations can acquire a high number of genetic alterations and then expand clonally, dysfunction of the mammalian Rad51 recombinase could play a major role in the multistep process of tumorigenesis. The data we present provide further strong support for this hypothesis. Using anti-Rad51 immunofluorescence staining, widely different tumor cell lines displayed increased numbers of nuclei with focally concentrated Rad51 protein compared with nonmalignant control cell lines. These nuclear foci are thought to represent a repairosome-type assembly of Rad51 and other proteins required for recombinational DNA repair. By Western blot analyses, the net amount of Rad51 protein was increased 2-7-fold in all tested tumor cell lines. Inhibition of de novo protein synthesis by cycloheximide treatment showed a similar half-life of Rad51 protein in normal and tumor cells. Fluorescence in situ hybridization experiments did not detect Rad51 gene amplifications in tumors. Because Northern blot analysis demonstrated highly elevated Rad51 mRNA levels, we conclude that the increases in Rad51 protein and nuclear foci formation in tumor cells are the result of transcriptional up-regulation.

• MID1, mutated in Opitz syndrome, encodes an ubiquitin ligase that targets phosphatase 2A for degradation

  Authors: Alexander Trockenbacher, Vanessa Suckow, John Foerster, Jennifer Winter, Sybille Krau, Hans-Hilger Ropers, Rainer Schneider, Susann Schweiger

  The gene MID1, the mutation of which causes X-linked Opitz G/BBB syndrome (OS, MIM 300000), encodes a microtubule-associated protein (MAP). We show that mutation of MID1 leads to a markedThe gene MID1, the mutation of which causes X-linked Opitz G/BBB syndrome (OS, MIM 300000), encodes a microtubule-associated protein (MAP). We show that mutation of MID1 leads to a marked accumulation of the catalytic subunit of protein phosphatase 2A (PP2Ac), a central cellular regulator. PP2Ac accumulation is caused by an impairment of a newly identified E3 ubiquitin ligase activity of the MID1 protein that normally targets PP2Ac for degradation through binding to its 4 regulatory subunit in an embryonic fibroblast line derived from a fetus with OS. Elevated PP2Ac causes hypophosphorylation of MAPs, a pathological mechanism that is consistent with the OS phenotype.