Cross-tissue enrichment patterns reveal functional clustering in normal human tissues from GTEx

Area of Science:

• Genomics
• Systems Biology
• Human Physiology

Background:

• Tissue specialization is crucial for human function, driven by unique gene expression patterns.
• Visualizing pathway-level enrichment and functional clustering of normal human tissues is essential for comparative analysis.

Purpose of the Study:

• To analyze RNA-sequencing data from 21 normal human tissues to understand pathway-level functional clustering.
• To establish a comparative platform for interpreting transcriptomic changes in health and disease.

Main Methods:

• Utilized RNA-sequencing data from 6,976 samples across 21 normal human tissues (GTEx project).
• Performed Gene Set Enrichment Analysis (GSEA) using KEGG, Gene Ontology Biological Processes (GOBP), and hallmark gene sets.
• Constructed tissue-tissue correlation matrices and performed functional clustering based on normalized enrichment scores (NES).

Main Results:

• Functional clustering separated tissues into two major groups: structural/immune/transport and neuroendocrine/contractile/metabolic.
• Identified 11 hallmark pathways with significant differential enrichment, including interferon signaling and metabolism.
• Validated three pathways (interferon-alpha response, apical junction assembly, spermatogenesis) with GOBP terms.
• Observed strong coherence in tissue pairs like breast-adipose and functional divergence in liver-testis.

Conclusions:

• Distinct functional regulation exists across normal human tissues at the pathway level.
• Provides a valuable pathway-level reference for interpreting physiological and disease-associated transcriptomic data.
• Lays groundwork for integrating multi-omics and single-cell data to enhance understanding of tissue-specific biology.