Related Experiment Video
Updated: Nov 19, 2025

Chromatin Isolation by RNA Purification ChIRP
Published on: March 25, 2012
Enhanced Over-Representation Analysis for the Differential Regulation of Birc5a and HIF2α-Knockdown Approaches
Chun-Cheng Liu1, Tao-Chuan Shih2, Tun-Wen Pai1,2
1Department of Computer Science and Engineering, National Taiwan Ocean University, Keelung, Taiwan.
Abstract:
Hypoxia-inducible factors (HIFs) and survivin (Birc5) genes are often considered important cancer drug targets for molecularly targeted therapy, as both genes play important roles in the cellular differentiation and development of neuronal cells. Pathway enrichment analysis is predominantly applied when interpreting the correlated behaviors of activated gene clusters. Traditional enrichment analysis is evaluated via p-values only, regardless of gene expression fold-change levels, gene locations, and possible hidden interactions within a pathway. Here, we combined these factors to retrieve significant pathways, as compared with traditional approaches. We performed RNA-seq analyses on Birc5a and HIF2α knocked down in zebrafish during the embryogenesis stage. Regarding Birc5a, two additional biological pathways, sphingolipid metabolism and herpes simplex infection, were identified; whereas for HIF2α, four biological pathways were re-identified, including ribosome biogenesis in eukaryotes, proteasome, purine metabolism, and complement and coagulation cascades. Our proposed approaches identified additional significant pathways directly related to cell differentiation or cancer, also providing comprehensive mechanisms for designing further biological experiments.
Insights
This study introduces a novel pathway enrichment analysis method, improving cancer drug target identification by integrating gene expression data. The approach revealed new biological pathways linked to cell differentiation and cancer.
Area of Science:
- Molecular biology
- Genetics
- Cancer research
Background:
- Hypoxia-inducible factors (HIFs) and survivin (Birc5) are key cancer drug targets involved in cell differentiation.
- Traditional pathway enrichment analysis relies solely on p-values, neglecting gene expression levels and interactions.
Purpose of the Study:
- To develop an improved pathway enrichment analysis method by incorporating gene expression fold-change, location, and interactions.
- To identify novel cancer-related pathways affected by Birc5a and HIF2α knockdown in zebrafish.
Main Methods:
- RNA-sequencing (RNA-seq) analysis was performed on zebrafish embryos with Birc5a and HIF2α knockdown.
- A novel pathway enrichment analysis approach was developed, integrating multiple factors beyond p-values.
Main Results:
- Knockdown of Birc5a identified sphingolipid metabolism and herpes simplex infection pathways.
- Knockdown of HIF2α re-identified ribosome biogenesis, proteasome, purine metabolism, and complement/coagulation cascade pathways.
- The novel approach identified additional significant pathways relevant to cell differentiation and cancer.
Conclusions:
- The enhanced pathway enrichment analysis provides a more comprehensive understanding of gene function and interactions.
- This method offers valuable insights for developing targeted cancer therapies and designing future biological experiments.

