title: R9AP overexpression alters phototransduction kinetics in iCre75 mice.
abstract: OBJECTIVE
  Determine the impact of rod photoreceptor-specific expression of Cre recombinase on the kinetics of phototransduction in the mouse eye and identify changes in gene expression that underlie any observed phenotypic differences.
  
  
  METHODS
  Transretinal ERG and single-cell suction electrode recordings were used to measure the kinetics of phototransduction in a mouse line exhibiting rod photoreceptor-specific Cre recombinase expression, and the results were compared with those from control non-Cre-expressing littermates. Gene expression changes were evaluated using RNA sequencing transcriptome analysis. The pattern of expression of Rgs9bp was determined by mapping sequencing reads to the mouse genome and performing 3'-rapid amplification of cDNA ends (3'-RACE).
  
  
  RESULTS
  Expression of the rod-specific iCre75 transgene was accompanied by accelerated phototransduction inactivation, likely due to overexpression of the Rgs9bp gene, which encodes the Rgs9 anchor protein (R9AP). R9AP upregulation stabilized the RGS9 GAP complex, altering phototransduction kinetics. 3'-Race identified an abundant, unexpected Rgs9bp-Prm1 fusion mRNA in Cre-expressing mouse retinas, which was determined to be derived from a second transgene present in the iCre75 line.
  
  
  CONCLUSIONS
  Here we report the presence of a second, R9AP-expressing transgene in the iCre75 mouse line, leading to altered kinetics of phototransduction. These results highlight an important caveat that must be considered when utilizing this mouse line for rod photoreceptor-specific gene loss of function studies.
authors: Department of Pharmacology, Case Western Reserve University, Cleveland, Ohio.
authors: Thomas R
authors: TR
authors: Sundermeier
authors: Frans
authors: F
authors: Vinberg
authors: Debarshi
authors: D
authors: Mustafi
authors: Xiaodong
authors: X
authors: Bai
authors: Vladimir J
authors: VJ
authors: Kefalov
authors: Krzysztof
authors: K
authors: Palczewski
mesh_terms: D000818:Animals; D004195:Disease Models, Animal; D004596:Electroretinography; D005136:Eye Proteins; D005786:Gene Expression Regulation; D015151:Immunoblotting; D019426:Integrases / Q000235:genetics / Q000378:metabolism; D055537:Light Signal Transduction / Q000235:genetics*; D008565:Membrane Proteins / Q000096:biosynthesis / Q000235:genetics*; D051379:Mice; D008810:Mice, Inbred C57BL; D008822:Mice, Transgenic; D016133:Polymerase Chain Reaction; D012333:RNA, Messenger / Q000235:genetics*; D012160:Retina / Q000166:cytology / Q000378:metabolism*; D017948:Retinal Rod Photoreceptor Cells / Q000166:cytology / Q000378:metabolism
chemical_list: D005136:Eye Proteins; D008565:Membrane Proteins; C508769:R9AP protein, mouse; D012333:RNA, Messenger; C045073:Cre recombinase; D019426:Integrases
keywords: Cre recombinase; R9AP; mouse; phototransduction; retina; rod photoreceptors