Restoring functional TDP-43 oligomers in ALS and laminopathic cellular models through baicalein-induced reconfiguration of TDP-43 aggregates.

A group of misfolded prone-to-aggregate domains in disease-causing proteins has recently been shown to adopt unique conformations that play a role in fundamental biological processes. These processes include the formation of membrane-less sub-organelles, alternative splicing, and gene activation and silencing. The cellular responses are regulated by the conformational switching of prone-to-aggregate domains, independently of changes in RNA or protein expression levels. Given this, targeting the misfolded states of disease-causing proteins to redirect them towards their physiological conformations is emerging as an effective therapeutic strategy for diseases caused by protein misfolding. In our study, we successfully identified baicalein as a potent structure-correcting agent. Our findings demonstrate that baicalein can reconfigure existing TDP-43 aggregates into an oligomeric state both in vitro and in disease cells. This transformation effectively restores the bioactivity of misfolded TDP-43 proteins in cellular models of ALS and premature aging in progeria. Impressively, in progeria cells where defective lamin A interferes with TDP-43-mediated exon skipping, the formation of pathological TDP-43 aggregates is promoted. Baicalein, however, restores the functionality of TDP-43 and mitigates nuclear shape defects in these laminopathic cells. This establishes a connection between lamin A and TDP-43 in the context of aging. Our findings suggest that targeting physiological TDP-43 oligomers could offer a promising therapeutic avenue for treating aging-associated disorders.