| TRAP1 (tumor necrosis factor receptor–associated protein 1, also known as mitochondrial Hsp90) is a mitochondria-enriched Hsp90-family chaperone that couples ATP-dependent conformational cycling with regulation of respiratory chain activity, redox homeostasis, and stress-adaptive signaling rather than housekeeping protein folding alone. The protein adopts the characteristic Hsp90 dimeric architecture with N‑terminal ATP-binding domains, middle client‑interaction domains, and C‑terminal dimerization regions, and forms stable homodimers whose ATPase cycle and client affinity are tuned by distinctive N‑terminal extensions and mitochondrial targeting sequences. TRAP1 interacts with multiple mitochondrial “client” proteins, including components of respiratory complexes II and IV and metabolic enzymes in the tricarboxylic acid cycle, and this chaperoning alters their conformation and catalytic activity to reshape oxidative phosphorylation efficiency, ATP output, and reactive oxygen species production under varying oxygen and nutrient conditions. TRAP1 inhibits succinate dehydrogenase (complex II) and dampens cytochrome c oxidase (complex IV) activity, leading to partial suppression of electron transport, reduced mitochondrial membrane potential and ROS formation, and a compensatory shift toward glycolytic ATP production, a metabolic configuration that favors survival in hypoxic or nutrient-poor microenvironments. TRAP1 also limits opening of the mitochondrial permeability transition pore and cytochrome c release and modulates the activity of kinases such as c‑Src, thereby intersecting with intrinsic apoptosis pathways and mitochondrial stress signaling to constrain caspase activation and support cell viability during oxidative or genotoxic insults. TRAP1 is frequently upregulated and associates with a bioenergetic switch toward aerobic glycolysis, increased proliferation, resistance to apoptosis, and altered responses to chemotherapeutic and targeted agents; genetic or pharmacologic inhibition of TRAP1 restores oxidative phosphorylation, elevates ROS, sensitizes cells to death stimuli, and impairs tumorigenic growth in preclinical models. In the nervous system, TRAP1 expression supports mitochondrial integrity and redox control, and its downregulation has been observed in Alzheimer’s disease and linked to heightened mitochondrial apoptosis and oxidative damage, while experimental TRAP1 loss or mutation in models of Parkinson’s disease enhances sensitivity to mitochondrial toxins and disrupts quality control pathways that depend on PINK1/Parkin-mediated mitophagy. |
