Localization of Human Retinal Expression of ELOVL4, an Evolutionarily Conserved Gene that Underlies an Autosomal Dominant Stargardt-like Macular Degeneration (STGD3)

Abstract

Abstract: : Purpose: We have been studying the molecular genetics of an autosomal dominant Stargardt-like disorder (STGD3) that maps to human chromosome 6 (Griesinger et al., Invest. Ophthalmol. Vis. Sci. (2000) 41:248-255; Lagali et al., Can. J. Ophthalmol. (2000) 5:315-324). In a collaborative effort we found that the mutation that gives rise to STGD3 is a 5-bp deletion in the ELOVL4 gene (Zhang et al., Nat. Genet. (2001) 27:89-93). This mutation has subsequently been verified by others in additional branches of the family that we have been studying (Edwards et al., Invest. Ophthalmol. Vis. Sci. (2001) 42:2652-2663). In order to obtain insight into the role of ELOVL4 in the retina, we have pursued additional molecular studies. In the current study we localize the expression of ELOVL4 at the protein level to human photoreceptor cells. In addition, we establish the evolutionarily conserved expression of ELOVL4 across different species at both the mRNA and protein levels. Methods: An ELOVL4 antibody was generated using a peptide derived from the open reading frame encoding the hypothetical protein predicted from the human ELOVL4 mRNA sequence. This antibody was used in immunohistochemical and Western analysis. In addition, the human ELOVL4 cDNA clone was used to perform Northern analysis of retinal RNA isolated from an array of different species in order to define the extent of conserved expression at the transcript level. Results: Immunohistochemical analysis of human retinal sections led to the detection of ELOVL4 protein in both rod and cone photoreceptor cells. Western analysis of human, cow, mouse, cat, and frog retinal protein extracts suggested a conserved detection of ELOVL4 protein in each species. Results of a multi-species Northern blot supported the notion of conserved expression of ELOVL4 across a variety of species. Conclusion: ELOVL4 protein is present in human rod and cone photoreceptor cells. Expression at both the protein and mRNA level is conserved across species. We thank the support of: Foundation Fighting Blindness, Canada (PW); E.A. Baker Foundation of the CNIB (PW,PSL); CIHR (PSL); Foundation Fighting Blindness, USA (RA); Research to Prevent Blindness (RA); NIH (RA).

Keywords: 528 proteins encoded by disease genes • 417 gene/expression • 476 molecular biology