Role of Activating Transcription Factor 4 in Metabolic, Neurologic, and Ocular Diseases.

Cells respond to metabolic and environmental challenges through the integrated stress response (ISR), a cellular process that maintains homeostasis under diverse stressors. ATF4 is a key player in this ISR, as it is activated via the PERK-eIF2α-ATF4 pathway. ATF4 induction can elicit adaptive responses, including the regulation of genes involved in metabolism and autophagy, to maintain homeostasis. However, ATF4 activation can also induce apoptosis, leading to a wide spectrum of diseases, including metabolic, neurologic, and ocular pathologies. This duality reflects the highly context-dependent nature of ATF4 signaling. This review aims to synthesize the role of ATF4 in metabolic dysfunction, neurodegenerative diseases, and ocular pathology; the mechanisms underlying its protective versus pathologic effects; and future directions to refine ATF4's potential as a clinical therapeutic target across different diseases.