Canine cone transducin-gamma gene and cone degeneration in the cd dog.
OBJECTIVE
To characterize the cDNA and the organization of the gene encoding the cone-specific gamma subunit of transducin (Tgamma c) and to examine this gene as a candidate for the recessively inherited cone photoreceptor degeneration in the cd dog.


METHODS
Canine Tgamma c cDNA was cloned and sequenced. Polymerase chain reaction (PCR) was used to define the Tgamma c gene structure, northern blot analysis to examine the level of expression of Tgamma c mRNA in control and cd-affected retinas, and immunocytochemistry to determine the presence and localization of Tgamma c in normal and cd retinas.


RESULTS
Immunocytochemical results showed Tgamma c localized to cone photoreceptor outer segments in the normal retina, whereas no Tgamma c immunoreactivity was observed in the cd retinas. However, the level of transcription and the primary structure of the cloned cDNA coding for the 69-amino acid protein were identical in retinas from wild-type and affected dogs.


CONCLUSIONS
Although Tgamma c immunoreactivity was specifically absent in the cd dog retina, no differences were detected between normal and cd retinas in the nucleotide sequence of Tgamma c mRNA or in its synthesis. These results indicate that a mutation in the Tgamma c gene may not be causally associated with the cd dog disease. These findings suggest that possible abnormalities in posttranslational modification of Tgamma c or defective assembly of the transducin alphabetagamma complex could lead to rapid degradation of Tgamma c.
Akhmedov
N B
NB
Jules Stein Eye Institute, University of California Los Angeles School of Medicine, 90095, USA.
Piriev
N I
NI
Pearce-Kelling
S
S
Acland
G M
GM
Aguirre
G D
GD
Farber
D B
DB
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D015152:Blotting, Northern / Q000662:veterinary; D003001:Cloning, Molecular; D018076:DNA, Complementary / Q000032:analysis*; D004283:Dog Diseases / Q000235:genetics* / Q000378:metabolism / Q000473:pathology; D004285:Dogs; D007124:Immunoenzyme Techniques / Q000662:veterinary; D008969:Molecular Sequence Data; D016133:Polymerase Chain Reaction / Q000662:veterinary; D012313:RNA / Q000302:isolation & purification; D012333:RNA, Messenger / Q000378:metabolism; D017949:Retinal Cone Photoreceptor Cells / Q000378:metabolism* / Q000473:pathology; D012162:Retinal Degeneration / Q000235:genetics / Q000378:metabolism / Q000473:pathology / Q000662:veterinary*; D017422:Sequence Analysis, DNA; D015293:Transducin / Q000235:genetics* / Q000378:metabolism
D018076:DNA, Complementary; D012333:RNA, Messenger; D012313:RNA; D015293:Transducin