Loss of ABCA4 from photoreceptor discs is associated with glial transcriptomic changes in retinal organoids

Abstract

Loss-of-function mutations in the ABCA4 gene cause Stargardt disease (STGD1), the most common inherited macular dystrophy leading to progressive central vision loss. Here, we generated hiPSC-derived retinal organoids harboring a premature stop codon in exon-24 of ABCA4 to evaluate the impact of this mutation on mRNA and protein levels in a human model. Immunofluorescence analysis revealed the absence of ABCA4 protein in the mutant photoreceptor outer segment discs, while single-cell RNA sequencing detected no major transcriptional alterations in rods and cones. Unexpectedly, differential gene expression and pathway enrichment analyses of Müller glial cells (MGCs) and astrocytes highlighted disruption of neuronal development, microenvironment of glial cells, intercellular communication, and programmed cell death pathways. These findings suggest that ABCA4 deficiency in photoreceptor discs may trigger early stress-associated transcriptomic responses in retinal glial cells prior to overt photoreceptor degeneration, potentially contributing to Stargardt disease pathogenesis.

Human induced pluripotent stem cells (hiPSCs) were engineered to generate ABCA4-mutant cell lines, later differentiated into retinal organoids as a model of Stargardt disease. The organoids showed loss of ABCA4 from the outer segment discs of rod and cone photoreceptors, while the mutant Müller glial cells and astrocytes exhibited transcriptional changes in pathways involved in neuronal development, microenvironment, and programmed cell death. Created in https://BioRender.com.