A Transcriptomics Analysis of the Regulation of Lens Fiber Cell Differentiation in the Absence of FGFRs and PTEN

The addition of 50% vitreous humor to the media bathing lens explants results in the induction of both fiber cell differentiation and a significant immune/inflammatory response. Although Fgfr loss blocks differentiation in lens epithelial explants, this loss is partially rescued by deleting Pten. To investigate the functions of the Fgfrs and Pten during lens fiber cell differentiation, we utilized a lens epithelial explant system and conducted RNA sequencing on vitreous humor-exposed explants lacking Fgfrs, or Pten or both Fgfrs and Pten. We found that Fgfr loss impairs both vitreous-induced differentiation and inflammation while the additional loss of Pten restores these responses. Furthermore, transcriptomic analysis suggested that PDGFR-signaling in FGFR-deficient explants is required to mediate the rescue of vitreous-induced fiber differentiation in explants lacking both Fgfrs and Pten. The blockage of β-crystallin induction in explants lacking both Fgfrs and Pten in the presence of a PDGFR-inhibitor supports this hypothesis. Our findings demonstrate that a wide array of genes associated with fiber cell differentiation are downstream of FGFR-signaling and that the vitreous-induced immune responses also depend on FGFR-signaling. Our data also demonstrates that many of the vitreous-induced gene expression changes Fgfr-deficient explants are rescued in explants lacking both Fgfrs and Pten.