TRiC/CCT interactome in photoreceptors

Project description: TRiC/CCT interactome in Rod Photoreceptors In this project we presented an in-vivo mouse model to map the TRiC/CCT chaperonin interactome in rod photoreceptors and determine how impaired protein folding affects retinal structure, signaling, and metabolism. By integrating affinity purification proteomics, loss of function models, targeted metabolomics, and multi-omics analysis, we identified a mechanistic connection between TRiC-dependent proteostasis and photoreceptor bioenergetics.

Key findings

• Rod-specific TRiC/CCT interactome: Affinity purification of epitope tagged TRiC identified 226 candidate TRiC-associated proteins, including established substrates and proteins involved in cytoskeletal organization, RNA processing, membrane trafficking, and cellular regulation.
• TRiC inhibition disrupts client folding: Expression of the inhibitory PhLPs isoform reduced canonical TRiC clients, including tubulins, transducin Gβ1, and triosephosphate isomerase 1 (TPI1), leading to defective rod outer-segment formation and impaired photoreceptor function.
• Metabolic energy crisis: TRiC deficient retinas showed reduced glycolytic and TCA-cycle intermediates, acylcarnitines, ATP, NAD, and NADH, indicating impaired glucose utilization, mitochondrial bioenergetics, and fatty-acid oxidation.
• Multi-omics integration and candidate metabolic regulators: Integrated proteomic and metabolomic analysis prioritized proteins such as Rab10, Anxa1, Uckl1, and Txndc9 as candidate molecular links between TRiC dysfunction and metabolic remodeling. The Rab10–GLUT4 axis represents a proposed mechanism that remains to be experimentally validated.
• Misfolded-substrate competition: A persistently unfolded Gβ1 mutant accumulated on TRiC and displaced other clients, demonstrating that substrate overload can sequester the chaperonin, amplify proteostasis imbalance, and promote photoreceptor degeneration.

Conclusion

TRiC/CCT is essential not only for folding structural and signaling proteins in rod photoreceptors, but also for maintaining cellular energy metabolism. Chaperonin inhibition or sequestration by an unfolded substrate produces a combined collapse of cytoskeletal integrity, phototransduction, and bioenergetics, providing a mechanistic framework for understanding how proteostasis failure contributes to retinal neurodegeneration.

For more detailed insights

• Published article: PLOS One
• DOI: 10.1371/journal.pone.0345843
• Research collaboration: David Smith Lab at WVU and Maxim Sokolov Lab at WVU