Exendin-4 alleviates Aβ1-40-induced apoptosis and calcium dysregulation in RPE cells through the CHP1/NHE1 complex.

Age-related macular degeneration (AMD) is a leading cause of visual impairment in elderly individuals and is influenced by various factors, such as age, genetics, and environmental conditions. While research into therapies for dry AMD is rapidly advancing, effective interventions are still lacking, underscoring the urgent need for new drug development. Recent studies have highlighted the multifaceted pharmacological activities of Exendin-4 (EX-4), including its anti-inflammatory, antioxidant, and antiapoptotic properties, along with its role in maintaining calcium homeostasis. The precise effects of EX-4 on AMD and its immediate target remain unclear. In this study, we investigated whether EX-4 could protect against Aβ1-40-induced AMD and explored the underlying mechanism. Our findings indicated that pretreatment with EX-4 alleviated apoptosis and restored calcium homeostasis both in vivo and in vitro. To identify the target of EX-4, we employed proteome microarrays and pulldown LC‒MS/MS analyses. Our results revealed that EX-4 bound to Calcineurin-like EF-hand protein 1(CHP1), reducing CHP1 protein expression in a concentration-dependent manner. This interaction led to a subsequent reduction in apoptosis and the normalization of intracellular Ca levels through the CHP1/NHE1 complex. Furthermore, we demonstrated that the inhibitory effects of EX-4 on apoptosis and calcium signaling were reversed by knocking down or overexpressing CHP1 in vitro. Finally, in AMD mice with CHP1-deficient retinas, the beneficial effects of EX-4 on apoptosis and calcium signaling were partially attenuated. In summary, our results suggest that the interaction of EX-4 with CHP1 has therapeutic potential for AMD, likely through alleviating apoptosis and restoring calcium homeostasis.