TUG-891

The upregulation of transmembrane protein 175 (TMEM175) has the potential to improve Parkinson's disease (PD) by aiding in the removal of α-synuclein aggregates. Understanding the structural basis of TMEM175 agonisms is crucial for uncovering its therapeutic potential for PD. Here, we have identified the first cryo-electron microscopy (cryo-EM) structure of human TMEM175 complexes with three agonists: DCY1020, DCY1040, and TUG-891. An open state of TMEM175 is unequivocally captured, laying the groundwork for designing more effective agonists. Further investigations using surface plasmon resonance, systematic mutagenesis, whole-endolysosome patch-clamp techniques, and molecular dynamics simulations consistently revealed that DCY1020/1040 binds at the interface between two subunits, inducing an open conformation further augmented by the synergistic agonist TUG-891. Notably, these agonists facilitate the removal of pathological α-synuclein and restore functions of PD-related TMEM175 variants in neurons. Our findings provide proof of concept that drug discovery targeting TMEM175 can develop agonists capable of effectively reducing pathological α-synuclein levels in PD.

Extensive research has confirmed that omega-3 fatty acids provide cardiovascular protection primarily by activating the G protein-coupled receptor 120 (GPR120) signaling pathway. However, natural activators of this receptor often lack sufficient strength and precision. TUG-891, a recently synthesized selective GPR120 activator, has displayed significant therapeutic potential in multiple disease. This investigation seeks to evaluate the neuroprotective effects of TUG-891 against ischemic cerebral injury. To this end, an in vivo murine model of distal middle cerebral artery occlusion (dMCAO) was employed, alongside an in vitro model utilizing oxygen-glucose deprivation/reperfusion in HT22 ​cells. The results indicated that TUG-891 significantly enhanced neurological function, reduced the volume of cerebral infarction, and alleviated pathological damage following dMCAO. Moreover, TUG-891 demonstrated a significant reduction in oxidative stress levels, a decrease of markers related to endoplasmic reticulum (ER) stress, and the modulation of critical apoptotic regulators, thereby inhibiting apoptosis in both in vivo and in vitro settings. Additionally, TUG-891 was found to affect the PI3K/Akt signaling pathway, with the application of the inhibitor LY294002 negating the protective effects of TUG-891 in vitro. This comprehensive study reveals TUG-891's therapeutic potential for ischemic stroke through multi-target mechanisms involving oxidative stress mitigation, ER stress regulation, and survival pathway activation. The consistent neuroprotection observed across biological models underscores its translational value for further clinical development.