# Cis-Regulation of the CFTR Gene in Pancreatic Cells

## TL;DR

This study explores how the CFTR gene is regulated in pancreatic cells, identifying key regulatory regions that may explain differences in disease severity in cystic fibrosis.

## Contribution

The study identifies novel cis-regulatory elements and their cooperative role in CFTR gene regulation in pancreatic cells.

## Key findings

- Active CREs were identified both near and outside the TAD of the CFTR gene.
- Multiple CREs upstream and downstream of CFTR show cooperative regulation through shared TF motifs.
- Comparative analysis reveals tissue-specific chromatin conformation differences between pancreatic and intestinal cells.

## Abstract

Genome organization is essential for precise spatial and temporal gene expression and relies on interactions between promoters and distal cis-regulatory elements (CREs), which constitute ~8% of the human genome. For the cystic fibrosis transmembrane conductance regulator (CFTR) gene, tissue-specific expression, especially in the pancreas, remains poorly understood. Unraveling its regulation could clarify the clinical heterogeneity observed in cystic fibrosis and CFTR-related disorders. To understand the role of 3D chromatin architecture in establishing tissue-specific expression of the CFTR gene, we mapped chromatin interactions and epigenomic regulation in Capan-1 pancreatic cells. Candidate CREs are validated by luciferase reporter assay and CRISPR knock-out. We identified active CREs not only around the CFTR gene but also outside the topologically associating domain (TAD). We demonstrate the involvement of multiple CREs upstream and downstream of the CFTR gene and reveal a cooperative effect of the −44 kb, −35 kb, +15.6 kb, and +37.7 kb regions, which share common predicted transcription factor (TF) motifs. We also extend our analysis to compare 3D chromatin conformation in intestinal and pancreatic cells, providing valuable insights into the tissue specificity of CREs in regulating CFTR gene expression.