Evolutionarily conserved ELOVL4 gene expression in the vertebrate retina.
OBJECTIVE
The gene elongation of very long chain fatty acids-4 (ELOVL4) has been shown to underlie phenotypically heterogeneous forms of autosomal dominant macular degeneration. In this study, the extent of evolutionary conservation and the existence and localization of retinal expression of this gene was investigated across a wide variety of species.


METHODS
Southern blot analysis of genomic DNA and bioinformatic analysis using the human ELOVL4 cDNA and protein sequences, respectively, were performed to identify species in which ELOVL4 orthologues and/or homologues are present. Retinal RNA and protein extracts derived from different species were assessed by Northern hybridization and immunoblot techniques to assess evolutionary conservation of gene expression. Immunohistochemical analysis of tissue sections prepared from various mammalian retinas was performed to determine the distribution of ELOVL4 and homologous proteins within specific retinal cell layers.


RESULTS
The existence of ELOVL4 sequence orthologues and homologues was confirmed by both Southern blot analysis and in silico searches of protein sequence databases. Phylogenetic analysis places ELOVL4 among a large family of known and putative fatty acid elongase proteins. Northern blot analysis revealed the presence of multiple transcripts corresponding to ELOVL4 homologues expressed in the retina of several different mammalian species. Conserved proteins were also detected among retinal extracts of different mammals and were found to localize predominantly to the photoreceptor cell layer within retinal tissue preparations.


CONCLUSIONS
The ELOVL4 gene is highly conserved throughout evolution and is expressed in the photoreceptor cells of the retina in a variety of different species, which suggests that it plays a critical role in retinal cell biology.
Lagali
Pamela S
PS
Department of Biological Sciences, University of Alberta, Edmonton, Alberta, Canada.
Liu
Jiafan
J
Ambasudhan
Rajesh
R
Kakuk
Laura E
LE
Bernstein
Steven L
SL
Seigel
Gail M
GM
Wong
Paul W
PW
Ayyagari
Radha
R
D000595:Amino Acid Sequence; D000818:Animals; D015152:Blotting, Northern; D015139:Blotting, Southern; D002415:Cats; D002417:Cattle; D002645:Chickens; D017124:Conserved Sequence; D004591:Electrophoresis, Polyacrylamide Gel; D019143:Evolution, Molecular; D005136:Eye Proteins / Q000235:genetics*; D015870:Gene Expression; D006801:Humans; D008253:Macaca mulatta; D008565:Membrane Proteins / Q000235:genetics*; D051379:Mice; D008969:Molecular Sequence Data; D020419:Photoreceptor Cells, Vertebrate / Q000378:metabolism*; D012313:RNA / Q000302:isolation & purification; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley
C418975:ELOVL4 protein, human; C498834:Elovl4 protein, mouse; D005136:Eye Proteins; D008565:Membrane Proteins; D012333:RNA, Messenger; D012313:RNA