TPM4 condensates glycolytic enzymes to fuel actin reorganization under hyperosmotic stress.
Abstract:
Actin homeostasis is fundamental for cell structure and consumes a large portion of cellular ATP. It has been documented in the literature that certain glycolytic enzymes can interact with actin, indicating an intricate interplay between the cytoskeleton and cellular metabolism. Here we report that hyperosmotic stress triggers actin severing and subsequent phase separation of the actin-binding protein TPM4. TPM4 condensates glycolytic enzymes such as HK2, PFKM, and PKM2, and adhere to and wrap around actin filaments. Notably, the condensates of TPM4 and glycolytic enzymes are enriched of NADH and ATP, suggestive of their functional importance in cell metabolism. At cellular level, actin filaments assembly is enhanced upon hyperosmotic stress and TPM4 condensation, while depletion of TPM4 impaired osmolarity-induced actin reorganization. At tissue level, co-localized condensates of TPM4 and glycolytic enzymes are observed in renal tissues subjected to hyperosmotic stress. Together, our findings suggest that stress-induced actin perturbation may act on TPM4 to organize glycolytic hubs that tether energy production to cytoskeletal reorganization.
