Sterol flux rewiring: Cholesterol biosynthesis as a dynamic signaling network

Cholesterol biosynthesis is among the best-characterized metabolic pathways in biology, yet a fundamental question remains unresolved: Why does this pathway generate more than twenty enzymatic reactions and numerous structurally distinct intermediates if cholesterol is its major biological end product? Over the past several decades, biochemical, genetic, pharmacological, biophysical, and lipidomic studies have progressively revealed that many sterol intermediates are not merely transient precursors. Instead, they possess distinct biophysical, signaling, and oxidative properties that contribute directly to cellular physiology and disease. However, these discoveries have largely been interpreted within separate biological and experimental contexts, including inherited disorders of cholesterol biosynthesis, membrane biology, nuclear receptor signaling, oxysterol metabolism, and pharmacological inhibition of distal sterol enzymes. Here, we propose that sterol flux rewiring provides an integrative framework that connects these independent observations into a unified view of cholesterol metabolism. In this framework, biological responses emerge from dynamic redistribution of metabolic flux, generating distinct sterol states characterized by specific membrane properties, signaling activities, oxidative potentials, and downstream metabolic outputs rather than by the accumulation of individual metabolites alone. This perspective explains how changes in sterol composition reshape membrane organization, oxidative diversification, and interconnected signaling networks, including the epoxycholestanoid pathway. It also provides a coherent framework for understanding how alterations in cholesterol metabolism contribute to development, immunity, neurobiology, ageing, regeneration, and cancer, while highlighting new opportunities for therapeutic strategies aimed at reprogramming sterol-state organization rather than simply inhibiting cholesterol synthesis.