• ABCA4 (ATP-binding cassette sub-family A member 4) is an important membrane transport protein primarily expressed in the photoreceptor cells (rods and cones) of the retina, where it plays a critical role in maintaining retinal health. The main function of ABCA4 is to transport toxic metabolic byproducts in the retina, particularly N-retinylidene-phosphatidylethanolamine (N-retinylidene-PE). Within photoreceptor cells, ABCA4 is responsible for clearing toxic retinoid derivatives produced during photochemical reactions, preventing their accumulation in retinal pigment epithelial (RPE) cells and thereby averting cellular damage and death. Mutations in the ABCA4 gene are the primary cause of Stargardt disease (type 1), a common inherited retinal disorder characterized by macular atrophy and vision loss that typically manifests during adolescence. ABCA4 mutations impair its transport function, leading to the buildup of toxic metabolites and ultimately triggering apoptosis in photoreceptor and RPE cells.
• The exons 3-50 of mouse Abca4 gene were knocked out in B-Abca4 KO mice.
• Protein expression analysis: Mouse ABCA4 was only detected in eye of wild-type mice, but not in homozygous B-Abca4 KO mice.
• mRNA expression analysis: Mouse Abca4 mRNA was detectable in eye of wild-type mice, but not in homozygous B-Abca4 KO mice

Gene targeting strategy for B-Abca4 KO mice.The exons 3-50 of mouse Abca4 gene were knocked out in B-Abca4 KO mice, resulting in a disruption of Abca4 gene.

Western blot analysis of ABCA4 protein expression in homozygous B-Abca4 KO mice. Various tissue lysates were collected from wild-type C57BL/6JNifdc mice (+/+) and homozygous B-Abca4 KO mice (-/-), and then analyzed by western blot with anti-ABCA4 antibody (Abcam, ab72955). 40 μg total proteins were loaded for western blotting analysis. Mouse ABCA4 was detected in eye of wild-type mice, but not in homozygous B-Abca4 KO mice.

Strain specific analysis of Abca4 mRNA expression in wild-type C57BL/6JNifdc and B-Abca4 KO mice by RT-PCR. Eye RNA were isolated from wild-type C57BL/6JNifdc (+/+) and homozygous B-Abca4 KO mice (-/-), then cDNA libraries were synthesized by reverse transcription, followed by PCR with mouse Abca4 primers. Mouse Abca4 mRNA was only detectable in wild-type mice, not in homozygous B-Abca4 KO mice.