Meirong Yang1,2, Yan Wang1,3, Ge Liang1, Zhendong Xu1,4, Charleen T Chu5, Huafeng Wei1. 1. Department of Anesthesiology and Critical Care, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA. 2. Department of Anesthesiology, Shanghai General Hospital, School of Medicine, Shanghai Jiaotong University, Shanghai, China. 3. Department of Anesthesiology, Shandong Provincial Hospital Affiliated to Shandong University, Jinan, China. 4. Department of Anesthesiology, Shanghai First Maternity and Infant Hospital, Tongji University School of Medicine, Shanghai, China. 5. Department of Pathology, Division of Neuropathology, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA.
Abstract
BACKGROUND: Disruption of intracellular Ca2+ homeostasis and associated autophagy dysfunction contribute to neuropathology in Alzheimer's disease (AD). OBJECTIVE: To study the effects of propofol on cell viability via its effects on intracellular Ca2+ homeostasis, and the impact of autophagy, in a neuronal model of presenilin-mutated familial AD (FAD). METHODS: We treated PC12 cells, stably transfected with either mutated presenilin-1 (L286V) or wild type (WT) controls, with propofol at different doses and durations, in the presence or absence of extracellular Ca2+, antagonists of inositol trisphosphate receptors (InsP3R, xestospongin C) and/or ryanodine receptors (RYR, dantrolene), or an inhibitor of autophagy flux (Bafilomycin). We determined cell viability, cytosolic Ca2+ concentrations ([Ca2+]c), vATPase protein expression, and lysosomal acidification. RESULTS: The propofol dose- and time-dependently decreased cell viability significantly more in L286V than WT cells, especially at the pharmacological dose (>50μM), and together with bafilomycin (40 nM). Clinically used concentrations of propofol (<20μM) tended to increase cell viability. Propofol significantly increased [Ca2+]c more in L286V than in WT cells, which was associated with decrease of vATPase expression and localization to the lysosome. Both toxicity and increased Ca2+ levels were ameliorated by inhibiting InsP3R/RYR. However, the combined inhibition of both receptors paradoxically increased [Ca2+]c, by inducing Ca2+ influx from the extracellular space, causing greater cytotoxicity. CONCLUSION: Impairment in autophagy function acts to deteriorate cell death induced by propofol in FAD neuronal cells. Cell death is ameliorated by either RYR or InsP3R antagonists on their own, but not when both are co-administered.
BACKGROUND: Disruption of intracellular Ca2+ homeostasis and associated autophagy dysfunction contribute to neuropathology in Alzheimer's disease (AD). OBJECTIVE: To study the effects of propofol on cell viability via its effects on intracellular Ca2+ homeostasis, and the impact of autophagy, in a neuronal model of presenilin-mutated familial AD (FAD). METHODS: We treated PC12 cells, stably transfected with either mutated presenilin-1 (L286V) or wild type (WT) controls, with propofol at different doses and durations, in the presence or absence of extracellular Ca2+, antagonists of inositol trisphosphate receptors (InsP3R, xestospongin C) and/or ryanodine receptors (RYR, dantrolene), or an inhibitor of autophagy flux (Bafilomycin). We determined cell viability, cytosolic Ca2+ concentrations ([Ca2+]c), vATPase protein expression, and lysosomal acidification. RESULTS: The propofol dose- and time-dependently decreased cell viability significantly more in L286V than WT cells, especially at the pharmacological dose (>50μM), and together with bafilomycin (40 nM). Clinically used concentrations of propofol (<20μM) tended to increase cell viability. Propofol significantly increased [Ca2+]c more in L286V than in WT cells, which was associated with decrease of vATPase expression and localization to the lysosome. Both toxicity and increased Ca2+ levels were ameliorated by inhibiting InsP3R/RYR. However, the combined inhibition of both receptors paradoxically increased [Ca2+]c, by inducing Ca2+ influx from the extracellular space, causing greater cytotoxicity. CONCLUSION: Impairment in autophagy function acts to deteriorate cell death induced by propofol in FAD neuronal cells. Cell death is ameliorated by either RYR or InsP3R antagonists on their own, but not when both are co-administered.