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GRN Inference and TF Activity - Usage Guide

Overview

Infer gene regulatory networks from bulk (or general) expression data and read transcription-factor protein activity from the resulting regulons. Edge inference uses mutual information (ARACNe-AP) or tree ensembles (GENIE3, GRNBoost2); activity inference uses VIPER/msVIPER. The central claim is the Califano-lab "activity, not edges" paradigm: an expression-derived GRN is an undirected association graph whose individual edges are unreliable, but a regulon read as a multiplexed reporter gives a robust estimate of a TF's protein activity -- which can be high even when the TF's own mRNA is unchanged. DREAM5 showed no single inference method dominates (ensembles win) and that synthetic-benchmark accuracy does not transfer to real eukaryotic data. This is the bulk counterpart to the single-cell scenic-regulons skill.

Prerequisites

BiocManager::install(c('viper', 'GENIE3'))
# ARACNe-AP is a Java tool built from source (https://github.com/califano-lab/ARACNe-AP)
# Python tree-ensemble alternative:
pip install arboreto

A candidate TF list matched to the expression matrix's gene namespace is required for edge inference.

Quick Start

Tell your AI agent what you want to do: - "Infer a TF-target network from my bulk RNA-seq with GENIE3" - "Build an ARACNe network and find master regulators with VIPER" - "Score per-sample TF activity for patient stratification" - "Which transcription factors are the master regulators of my tumor vs normal contrast?"

Example Prompts

Edge Inference

"I have a bulk RNA-seq matrix and a TF list. Reverse-engineer a regulatory network with GENIE3."

"Run ARACNe-AP with bootstrapping and consolidation to build a mutual-information network."

Master Regulators and Activity

"Build a regulon from my ARACNe network and run msVIPER to rank master regulators of disease."

"Compute a per-sample VIPER activity matrix and cluster patients by TF activity."

Robustness

"Infer the network with multiple methods and combine them into a consensus (wisdom of crowds)."

What the Agent Will Do

  1. Orient the expression matrix correctly (genes in rows for GENIE3) and load the TF list
  2. Run edge inference (GENIE3 random forests, or ARACNe-AP bootstraps + consolidation)
  3. Assemble a regulon, assigning each target a Mode-of-Regulation sign
  4. Build a null model and run msVIPER (master regulators) or VIPER (per-sample activity)
  5. Report activity by NES, not node degree, and evaluate edges with AUPRC where a gold standard exists

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