# Regulatory role of PI3K signaling pathways in lens differentiation and function

> **NIH NIH R01** · THOMAS JEFFERSON UNIVERSITY · 2021 · $502,755

## Abstract

Using a combined ATACseq and RNAseq approach our studies have provided the first evidence that changes
in chromatin accessibility are crucial to the differentiation state-specific expression of a wide variety genes
essential to the transition from lens epithelial to fiber cells. These studies also identified key DNA regulatory
regions and transcription factor binding sites likely to regulate a wide-range of lens genes, most importantly
FOXO4. Genes with requisite roles in lens cell differentiation that contain a consensus DNA binding sequence
for FOXO4 include EPHA2, NrCAM, δ-crystallin, Notch1 and FYCO1. The FOXO family, including FOXO4, is
regulated by the PI3K/Akt signaling pathway. Phosphorylation of FOXO4 by PI3K/Akt sequesters it in the
cytoplasm and suppression of PI3K/Akt signaling is required for FOXO4 import to the nucleus for its role in
regulating gene expression. The function of FOXO4 has never been examined in the lens. We propose to
establish the role of PI3K/AKT regulation of FOXO4-dependent gene expression in lens fiber cell
differentiation. This will be accomplished by 1) identifying the requirement for PI3K/Akt inhibition for the nuclear
translocation of FOXO4 in the transition of lens epithelial to fiber cells; 2) establishing the link between
PI3K/Akt inhibition and the expression of lens differentiation-specific genes containing FOXO4 binding
sequences; 3) demonstrating the binding of FOXO4 to distinct chromatin accessible DNA regulatory regions in
genes crucial to lens differentiation using targeted-CHIP assays; and 4) establishing the spectrum, range and
spatial expression patterns of genes regulated by FOXO4 during lens cell differentiation. We also discovered
that the PI3K/Akt signaling axis plays an essential role in regulating the timing and mechanism that removes
mitochondria, ER and Golgi from the central light path and that multiple PI3K-downstream signaling pathways
are required for the process of eliminating nuclei to form the lens Organelle Free Zone (OFZ). This process is
required to create a mature lens capable of focusing light images on the retina. We will explore how PI3K
signaling pathways regulate the elimination of nuclei and other organelles to form the lens Organelle Free
Zone in studies aimed at 1) identifying the functions of individual PI3K p110 catalytic subunits in regulating
formation of the OFZ; 2) confirming that the induction of autophagy following inhibition of the PI3K/Akt signaling
axis is responsible for the removal of mitochondria, ER and Golgi from the developing lens; 3) determining the
link between inactivation of different PI3K signaling pathways and activation of the mechanistic targets required
to eliminate nuclei to form the OFZ; and 4) investigating the potential link between the ring of Akt activity at the
border of cortical and nuclear fiber cells and the regulation of the outer boundary of the OFZ.

## Key facts

- **NIH application ID:** 10113627
- **Project number:** 5R01EY026478-06
- **Recipient organization:** THOMAS JEFFERSON UNIVERSITY
- **Principal Investigator:** Marc Kantorow
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2021
- **Award amount:** $502,755
- **Award type:** 5
- **Project period:** 2015-12-01 → 2025-02-28

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10113627

## Citation

> US National Institutes of Health, RePORTER application 10113627, Regulatory role of PI3K signaling pathways in lens differentiation and function (5R01EY026478-06). Retrieved via AI Analytics 2026-05-22 from https://api.ai-analytics.org/grant/nih/10113627. Licensed CC0.

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