Sepsis-associated liver dysfunction is a life-threatening condition with a high mortality rate and no mechanism-based therapy. In this study, we identify the cross-linking enzyme transglutaminase 2 (TG2) as a driver of liver inflammation by activating macrophages in a mouse model of sepsis. Pharmacological inhibition of TG2 improves survival and reduces multiorgan inflammation, with the liver as a primary therapeutic target. Mechanistically, TG2 activity was up-regulated in macrophages, where it cross-linked vimentin to promote oligomerization and intermediate filament remodeling. Genetic ablation of TG2 or vimentin suppressed macrophage cytokine production and attenuated lipopolysaccharide-induced inflammation. Notably, vimentin-deficient macrophages exhibited enhanced proteasome recruitment to detergent-insoluble protein aggregates, accelerating the degradation of proinflammatory mediators such as Traf6, thereby dampening nuclear factor κB signaling. Proteomic profiling revealed a previously unrecognized Rab27a-positive vesicle trafficking pathway for inflammatory aggregate clearance. Together, these findings define a TG2–vimentin axis that controls macrophage activation through proteostasis regulation, linking cytoskeletal remodeling to inflammatory signaling.
Ya-Li Xu, Ting Su, Hricha Mishra et al.· Science Advances· 0 citations
MYCN is a key oncogenic driver in hepatocellular carcinoma (HCC) and a therapeutic challenge due to the historical undruggability of MYC transcription factors (TFs). Using a high-throughput MYCN promoter-luciferase reporter, we identified PhiKan 083 (PK83), a small molecule previously recognized as a mutant p53 activator, that dose-dependently suppresses MYCN expression in HCC cells. PK83 impaired the proliferation and survival of MYCN-high HCC cells, inducing DNA damage, apoptosis, and loss of clonogenic and spheroid growth potential, while sparing MYCN-low HCC cells and normal hepatocytes. Structure-activity analysis revealed that polar, hydrogen-bond-capable substituents on PK83's tricyclic scaffold are critical for its activity. Although PK83 broadly activates p53 signaling, its cytotoxicity in MYCN-high cells is not strictly dependent on intact p53, as confirmed in p53-knockout systems. Transcriptome profiling and pathway analysis demonstrated robust suppression of MYC/MYCN targets along with modulation of pathways linked to stress, differentiation, and metabolism. In primary HCC tumors, PK83-downregulated TFs, including oncogenic TFs ZMIZ1 and TARBP1, positively correlated with MYCN, whereas upregulated stress-responsive TFs ATF3 and FOSL2 showed a negative correlation. These findings suggest that PK83 suppresses MYCN expression and preferentially affects MYCN-high HCC cells in a p53-independent manner, warranting further preclinical investigation of PK83 and related compounds in MYCN-associated cancers.