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Decreased catalytic activity and altered activation properties of PDE6C mutants associated with autosomal recessive achromatopsia

Grau, Tanja; Artemyev, Nikolai O.; Rosenberg, Thomas; Dollfus, Helene; Haugen, Olav H.; Sener, E. Cumhur; Jurklies, Bernhard; Andréasson, Sten LU ; Kernstock, Christoph and Larsen, Michael, et al. (2011) In Human Molecular Genetics 20(4). p.719-730
Abstract
Mutations in the gene encoding the catalytic subunit of the cone photoreceptor phosphodiesterase (PDE6C) have been recently reported in patients with autosomal recessive inherited achromatopsia (ACHM) and early-onset cone photoreceptor dysfunction. Here we present the results of a comprehensive study on PDE6C mutations including the mutation spectrum, its prevalence in a large cohort of ACHM/cone dysfunction patients, the clinical phenotype and the functional characterization of mutant PDE6C proteins. Twelve affected patients from seven independent families segregating PDE6C mutations were identified in our total patient cohort of 492 independent families. Eleven different PDE6C mutations were found including two nonsense mutations, three... (More)
Mutations in the gene encoding the catalytic subunit of the cone photoreceptor phosphodiesterase (PDE6C) have been recently reported in patients with autosomal recessive inherited achromatopsia (ACHM) and early-onset cone photoreceptor dysfunction. Here we present the results of a comprehensive study on PDE6C mutations including the mutation spectrum, its prevalence in a large cohort of ACHM/cone dysfunction patients, the clinical phenotype and the functional characterization of mutant PDE6C proteins. Twelve affected patients from seven independent families segregating PDE6C mutations were identified in our total patient cohort of 492 independent families. Eleven different PDE6C mutations were found including two nonsense mutations, three mutations affecting transcript splicing as shown by minigene assays, one 1 bp-insertion and five missense mutations. We also performed a detailed functional characterization of six missense mutations applying the baculovirus system to express recombinant mutant and wildtype chimeric PDE6C/PDE5 proteins in Sf9 insect cells. Purified proteins were analyzed using Western blotting, phosphodiesterase (PDE) activity measurements as well as inhibition assays by zaprinast and P gamma. Four of the six PDE6C missense mutations led to baseline PDE activities and most likely represent functional null alleles. For two mutations, p.E790K and p.Y323N, we observed reduction in PDE activity of approximately 60% and 80%, respectively. We also observed differences for P gamma inhibition. The p.E790K mutant, with an IC50 value of 2.7 nM is 20.7-fold more sensitive for P gamma inhibition, whereas the p.Y323N mutant with an IC50 of 158 nM is 3-fold less sensitive when compared with the wildtype control. (Less)
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Human Molecular Genetics
volume
20
issue
4
pages
719 - 730
publisher
Oxford University Press
external identifiers
  • wos:000286469400009
  • scopus:78751683502
ISSN
0964-6906
DOI
10.1093/hmg/ddq517
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English
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e5c03eb1-70a4-446a-a4ac-812fa4312177 (old id 1872893)
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2011-04-04 07:39:22
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@article{e5c03eb1-70a4-446a-a4ac-812fa4312177,
  abstract     = {Mutations in the gene encoding the catalytic subunit of the cone photoreceptor phosphodiesterase (PDE6C) have been recently reported in patients with autosomal recessive inherited achromatopsia (ACHM) and early-onset cone photoreceptor dysfunction. Here we present the results of a comprehensive study on PDE6C mutations including the mutation spectrum, its prevalence in a large cohort of ACHM/cone dysfunction patients, the clinical phenotype and the functional characterization of mutant PDE6C proteins. Twelve affected patients from seven independent families segregating PDE6C mutations were identified in our total patient cohort of 492 independent families. Eleven different PDE6C mutations were found including two nonsense mutations, three mutations affecting transcript splicing as shown by minigene assays, one 1 bp-insertion and five missense mutations. We also performed a detailed functional characterization of six missense mutations applying the baculovirus system to express recombinant mutant and wildtype chimeric PDE6C/PDE5 proteins in Sf9 insect cells. Purified proteins were analyzed using Western blotting, phosphodiesterase (PDE) activity measurements as well as inhibition assays by zaprinast and P gamma. Four of the six PDE6C missense mutations led to baseline PDE activities and most likely represent functional null alleles. For two mutations, p.E790K and p.Y323N, we observed reduction in PDE activity of approximately 60% and 80%, respectively. We also observed differences for P gamma inhibition. The p.E790K mutant, with an IC50 value of 2.7 nM is 20.7-fold more sensitive for P gamma inhibition, whereas the p.Y323N mutant with an IC50 of 158 nM is 3-fold less sensitive when compared with the wildtype control.},
  author       = {Grau, Tanja and Artemyev, Nikolai O. and Rosenberg, Thomas and Dollfus, Helene and Haugen, Olav H. and Sener, E. Cumhur and Jurklies, Bernhard and Andréasson, Sten and Kernstock, Christoph and Larsen, Michael and Zrenner, Eberhart and Wissinger, Bernd and Kohl, Susanne},
  issn         = {0964-6906},
  language     = {eng},
  number       = {4},
  pages        = {719--730},
  publisher    = {Oxford University Press},
  series       = {Human Molecular Genetics},
  title        = {Decreased catalytic activity and altered activation properties of PDE6C mutants associated with autosomal recessive achromatopsia},
  url          = {http://dx.doi.org/10.1093/hmg/ddq517},
  volume       = {20},
  year         = {2011},
}