Biology subjects

Jeyabalan Srikaran, J.

Publications and source records attributed to Jeyabalan Srikaran, J..

2 recordsLinked to original sources

bioRxiv2026

Pharmacological rescue of cilia trafficking defects in IFT140 retinal organoid and RPE models of retinal dystrophy

Pathogenic variants in IFT140 are associated with a spectrum of syndromic and non-syndromic ciliopathies, with retinal degeneration as a common feature. Despite advances in understanding IFT140 function across various tissues, human retina-specific models are lacking. Here, we show that knock-in mice homozygous for the IFT140 patient variant c.932A>G (p.Y311C) did not develop retinal degeneration, while mice with the homozygous variant c.1451C>T (p.T484M), associated with non-syndromic retinal dystrophy, were embryonic lethal. Therefore, to understand the effect of these variants on retinal homeostasis, we generated novel human in vitro models of IFT140-associated retinal dystrophy, including CRISPR/Cas9 IFT140 knock-out (IFT140KO) induced pluripotent stem cells (iPSC) and patient-derived iPSC retinal pigment epithelium (iPSC-RPE) and retinal organoids (iPSC-ROs). IFT140KO iPSC-RPE cells display stubby cilia compared to isogenic controls, while IFT140T484M/T484Mpatient-derived iPSC-RPE cells exhibit slightly shorter cilia and cilia tip protein accumulation. Both IFT140KO and IFT140T484M/T484M iPSC-ROs show accumulation of cilia proteins at the connecting cilium and outer segment of photoreceptors, and mislocalization of rhodopsin to the inner segments and outer nuclear layer. Pharmacological screening of compounds previously reported to improve cilia structure identified the flavonoid eupatilin as the most effective molecule. Treatment with eupatilin improved cilium length and IFT traffic in iPSC-RPE, and IFT traffic and rhodopsin localization in iPSC-ROs. These findings emphasize the importance of human stem cell derived models to investigate tissue specific disease mechanisms and highlight the therapeutic potential of eupatilin to ameliorate cilia defects in retinal tissue.

neuroscience↗

bioRxiv2023

De-suppression of mesenchymal cell identities and variable phenotypic outcomes associated with knockout of Bbs1.

Bardet-Biedl syndrome (BBS) is an archetypal ciliopathy caused by dysfunction of primary cilia. BBS affects multiple tissues, including the kidney, eye and hypothalamic satiety response. Understanding pan-tissue mechanisms of pathogenesis versus those which are tissue specific, and gauging their associated inter-individual variation owing to genetic background and stochastic processes, is of paramount importance in syndromology. The BBSome is a membrane trafficking and intraflagellar transport (IFT) adaptor protein complex formed by 8 BBS proteins, including BBS1, which is the most commonly mutated gene in BBS. To investigate disease pathogenesis we generated a series of clonal renal collecting duct IMCD3 cell lines carrying defined biallelic nonsense or frameshift mutations in Bbs1, as well as a panel of matching wild-type CRISPR control clones. Using a phenotypic screen and an unbiased multi-omics approach we note significant clonal variability for all assays, emphasising the importance of analysing panels of genetically-defined clones. Our results suggest that BBS1 is required for suppression of mesenchymal cell identities as IMCD3 cell passage number increases. This was associated with a failure to express epithelial cell markers and tight junction formation, which was variable amongst clones. Transcriptomic analysis of hypothalamic preparations from BBS mutant mice, and BBS patient fibroblasts, suggested that dysregulation of epithelial-to-mesenchymal transition (EMT) genes is a general predisposing feature of BBS across tissues. Collectively this work suggests that the dynamic stability of the BBSome is essential for suppression of mesenchymal cell identities as epithelial cells differentiate.

genetics↗