Oxidative stress of the retinal pigment epithelium (RPE) is a major risk factor for age-related macular degeneration (AMD). As a dry AMD model via oxidative stress, sodium iodate (NaIO₃), which is primarily toxic to the RPE, has often been used at a high dose to cause RPE death for studying photoreceptor degeneration. Thus, characterization of RPE damage by a low dose of NaIO₃ is still limited. To quantify RPE damage caused by NaIO₃ in mice, we recently developed a morphometric method using RPE flat-mounts. Here, we report that NaIO₃ has a narrow range of dose–effect correlation at 11–18 mg/kg body weight in male C57BL/6J mice. We evaluated the usefulness of our quantification method in two experimental settings. First, we tested the effect of NF-κB inhibition on NaIO₃-induced RPE damage in male C57BL/6J mice. IKKβ inhibitor BAY 651942 suppressed upregulation of NF-κB targets and protected the RPE from oxidative stress. Second, we tested sex-specific differences in NaIO₃-induced RPE damage in C57BL/6J mice using a low dose near the threshold. NaIO₃ caused more severe RPE damage in female mice than in male mice. These results demonstrate the usefulness of the quantification method and the importance of fine-tuning of the NaIO₃ dose. The results also show the therapeutic potential of IKKβ inhibition for oxidative stress-related RPE diseases, and reveal previously-unrecognized sex-specific differences in RPE susceptibility to oxidative stress.

Epithelial-mesenchymal transition (EMT) of the retinal pigment epithelium (RPE) is associated with several blinding retinal diseases. Using proteomics and phosphoproteomics studies of human induced pluripotent stem cell-derived RPE monolayers with induced EMT, we capture kinase/phosphatase signaling cascades 1 h and 12 h after induction to better understand the pathways mediating RPE EMT. Induction by co-treatment with transforming growth factor β and tumor necrosis factor alpha (TGNF) or enzymatic dissociation perturbs signaling in many of the same pathways, with striking similarity in the respective phosphoproteomes at 1 h. Liver hyperplasia and hepatocyte growth factor (HGF)-MET signaling exhibit the highest overall enrichment. We also observe that HGF and epidermal growth factor signaling, two cooperative pathways inhibited by EMT induction, regulate the RPE transcriptional profile.

The polygenic nature of schizophrenia (SCZ) implicates many variants in disease development. Rare variants of high penetrance have been shown to contribute to the disease prevalence. Whole-exome sequencing of a large three-generation family with SCZ and bipolar disorder identified a single segregating novel, rare, non-synonymous variant in the gene CASKIN1. The variant D1204N is absent from all databases, and CASKIN1 has a gnomAD missense score Z = 1.79 and pLI = 1, indicating its strong intolerance to variation. We find that introducing variants in the proline-rich region where the D1204N resides results in significant cellular changes in iPSC-derived neurons, consistent with CASKIN1’s known functions. We observe significant transcriptomic changes in 368 genes (padj < 0.05) involved in neuronal differentiation and nervous system development. We also observed nominally significant changes in the frequency of action potentials during differentiation, where the speed at which the edited and unedited cells reach the same level of activity differs. Our results suggest that CASKIN1 is an excellent gene candidate for psychosis development with high penetrance in this family.

Epithelial–mesenchymal transition (EMT) of the retinal pigment epithelium (RPE) is associated with several potentially blinding retinal diseases. Proteomic and phosphoproteomic studies were performed on human pluripotent stem cell-derived RPE (hPSC-RPE) monolayers to better understand the pathways mediating RPE EMT. EMT was induced by enzymatic dissociation or by co-treatment with transforming growth factor beta (TGFβ) and tumor necrosis factor alpha (TNFα; TGNF). The global and phosphoproteomes were analyzed at 1 hr post EMT induction to capture early events in kinase/phosphatase signaling cascades and at 12 hrs to define early changes in protein abundance. Pathway enrichment analysis revealed that TGNF and Dissociation rapidly perturbed signaling in many of the same pathways, with striking similarity in the phosphoproteome at 1 hr. Surprisingly, functions related to liver cell proliferation and hyperplasia were strongly enriched in the phosphosites altered by both treatments at 1 hr and in protein abundance changes at 12 hrs. Hepatocyte Growth Factor-cMET signaling exhibited the strongest overall enrichment in both treatments. These signaling pathways may serve as suitable targets for the development of therapeutic strategies for the inhibition of RPE EMT, and thus progression of several debilitating visual diseases.