Crosstalk of protein clearance, inflammasome, and Ca2+ channels in retinal pigment epithelium derived from age- related macular degeneration patients

Degeneration and/or dysfunction of retinal pigment epithelium (RPE) is generally detected as the formation of intracellular and extracellular protein aggregates, called lipofuscin and drusen, respectively, in patients with age-related macular degeneration (AMD), the leading cause of blindness in the elderly population. These clinical hallmarks are linked to dysfunctional protein homeostasis and inflammation and furthermore, are both regulated by changes in intracellular Ca2+ concentration. While many other cellular mechanisms have been considered in the investigations of AMD-RPE, there has been relatively little work on understanding the in-teractions of protein clearance, inflammation, and Ca2+ dy-namics in disease pathogenesis. Here we established induced pluripotent stem cell-derived RPE from two patients with advanced AMD and from an age-and gender-matched control subject. We studied autophagy and inflammasome activation under disturbed proteostasis in these cell lines and investigated changes in their intracellular Ca2+ concentration and L-type voltage-gated Ca2+ channels. Our work demonstrated dysre-gulated autophagy and inflammasome activation in AMD-RPE accompanied by reduced intracellular free Ca2+ levels. Inter-estingly, we found currents through L-type voltage-gated Ca2+ channels to be diminished and showed these channels to be significantly localized to intracellular compartments in AMD-RPE. Taken together, the alterations in Ca2+ dynamics in AMD-RPE together with dysregulated autophagy and inflam-masome activation indicate an important role for Ca2+ signaling in AMD pathogenesis, providing new avenues for the development of therapeutic approaches.

Automated summary

Degeneration and dysfunction of retinal pigment epithelium (RPE) in patients with age-related macular degeneration (AMD) is closely related to protein aggregates formation, protein homeostasis disturbance, inflammation and changes in intracellular Ca2+ concentration. This study investigated autophagy, inflammasome activation, and L-type voltage-gated Ca2+ channels in RPE derived from advanced AMD patients and a control subject. Dysregulated autophagy and inflammasome activation accompanied by reduced intracellular free Ca2+ levels were observed in AMD-RPE. The study also found diminishment of currents through L-type voltage-gated Ca2+ channels and their significant localization in intracellular compartments in AMD-RPE. These findings suggest an important role of Ca2+ signaling in AMD pathogenesis, opening new avenues for therapeutic approaches.