Regulatory network changes between cell lines and their tissues of origin

Area of Science:

• Biomedical Research
• Genomics
• Systems Biology

Background:

• Cell lines are crucial biomedical research tools, often used as tissue surrogates.
• Existing knowledge acknowledges cellular and transcriptomic differences between cell lines and tissues.
• A systematic analysis of regulatory process differences between cell lines and their tissue of origin was lacking.

Purpose of the Study:

• To systematically compare the transcriptional regulatory differences between cell lines and their tissues of origin.
• To investigate the impact of regulatory changes on gene expression patterns in cell lines.
• To provide insights into the reliability of cell lines as models for human tissues.

Main Methods:

• Utilized RNA-Seq data from the Genotype-Tissue Expression (GTEx) project.
• Performed large-scale transcriptional and regulatory network analysis.
• Compared 127 paired Epstein-Barr virus transformed lymphoblastoid cell lines (LCLs) with whole blood samples, and 244 paired primary fibroblast cell lines with skin samples.
• Validated transcription factor (TF) regulatory changes using independent ChIP-seq data.

Main Results:

• Gene expression analysis confirmed cell lines retain tissue-specific signatures, though at reduced levels.
• Network analysis revealed significant, previously unreported alterations in transcription factor (TF) regulation.
• Cell cycle genes were over-expressed in cell lines due to reduced repressive TF targeting.
• Confirmed regulatory changes for four TFs, including SMAD5, via ChIP-seq.

Conclusions:

• Identified novel insights into regulatory mechanisms driving expression differences between cell lines and tissues.
• Observed substantial changes in TF regulation suggest network alterations are critical.
• Emphasized the need to consider regulatory network changes, not just transcriptional levels, when interpreting cell line model data.