ISR Modulators in Neurological Diseases

The dysfunction of different cells lies in the pathogenesis of neurological diseases and is usually associated with cellular stress. Various stressors trigger the integrated stress response (ISR) signaling, whose highly conserved mechanism is primarily aimed at protecting a stress-exposed cell to cope as safely as possible with such stressful conditions. On the contrary, if a cell is unable to cope with excessive stress, the ISR can induce apoptosis. The ISR mechanism, whose main stage is the inhibition of translation machinery in favor of the synthesis of specific proteins, including the transcription factors ATF3, ATF4, CEBPA, and CEBPB, which function only as dimers and determine the uniqueness of the ISR response in each individual case, thus ensures different outcomes of the ISR. Inhibition of global protein synthesis is achieved through phosphorylation of eIF2α by PERK, HRI, PKR, or GCN2. To date, a number of compounds have been developed that modulate the ISR, including activators and inhibitors of the abovementioned ISR kinases as well as modulators of p-eIF2α dephosphorylation. They target different ISR stages, allowing a broad ISR modulation strategy. At the same time, there are no drugs that are both exceptionally safe and effective for the treatment of several neurological diseases, so there is an urgent need for new approaches to the treatment of these disorders. In this review, we represent ISR signaling as an important participant in the pathogenesis of neurological diseases. We also describe how various ISR modulators may become a part of future therapies for these diseases.