# Mechanism of circRNA_4083 Circularization and Its Role in Regulating Cell Viability

## TL;DR

This study explores circRNA_4083 in chickens, showing it helps cells survive and may protect against genetic damage.

## Contribution

The study identifies circRNA_4083 as a novel regulator of cell viability and genomic stability in chickens.

## Key findings

- circRNA_4083 is derived from exons 22 and 23 of the MSH3 gene and is stabilized by flanking intronic sequences.
- Overexpression of circRNA_4083 reduces apoptosis and increases cell viability in DF-1 cells.
- circRNA_4083 interacts with miRNAs and target genes involved in genomic stability pathways like NHEJ.

## Abstract

This study investigated circRNA_4083, which is a stable circular RNA which originates from the MSH3 gene of chicken. It is highly expressed in cardiac, pulmonary and renal tissues. Its biogenesis depends on flanking genomic sequences. CircRNA_4083 overexpression reduced apoptosis and enhanced cell proliferation, indicating its role in promoting cellular viability. Bioinformatics analysis indicates that circRNA_4083 interacts with RNA-binding molecules and regulates pathways that are crucial for genomic stability, possibly protecting the genome from damage. These findings underscore its importance in maintaining cellular health. By elucidating circRNA-driven mechanisms, this work advances the understanding of non-coding RNA functions in poultry biology, offering insights for developing strategies to improve disease resilience and productivity in agricultural practices.

Circular RNAs (circRNAs), a class of covalently closed non-coding RNAs, are pivotal regulators of gene expression and contributors to disease pathogenesis. This study elucidated the biogenesis, functional significance, and regulatory network of circRNA_4083, a novel exon-derived circRNA originating from exons 22 and 23 of the MSH3 gene in chicken. Through comprehensive molecular characterization—including Sanger sequencing, RNase R digestion assays, and subcellular localization—we confirmed the robust stability and predominant cytoplasmic localization of circRNA_4083 across diverse chicken tissues. Mechanistic investigations revealed that reverse complementary sequences within flanking intronic regions are indispensable for its circularization, as demonstrated by overexpression plasmids (#1–#4) in DF-1 cells. Functional analyses demonstrated that circRNA_4083 significantly inhibited cell apoptosis and increased cellular viability. Integrative bioinformatics approaches predicted a competing endogenous RNA (ceRNA) network comprising 12 miRNAs and 2132 target genes (FDR < 0.05), with significant enrichment in pathways critical to genomic stability, including non-homologous end joining (NHEJ) and ubiquitin-mediated proteolysis. These findings position circRNA_4083 as a key modulator of cellular viability and genomic integrity, with potential implications for avian leukosis virus-J (ALV-J) pathogenesis and resistance breeding strategies. This work advances our understanding of circRNA-driven regulatory mechanisms in avian species and underscores their relevance in poultry health.