Free Radical Biology and Medicine
The plasma membrane calcium ATPase (PMCA) is a neuronal calcium transporter that plays a critical role in regulating intracellular calcium levels by pumping calcium out of cells, against its 10,000-fold concentration gradient. Previous studies from our laboratory have shown that PMCA undergoes a progressive reduction in activity and protein levels with increasing age and in neurodegenerative disorders. We have further demonstrated the unique sensitivity of PMCA to oxidative stress. Loss of PMCA causes dysregulation of calcium homeostasis, creates calcium toxicity, and induces cell death. A mechanism to prevent loss of PMCA and/or boost its activity would serve as a therapeutic intervention to protect neurons. Polyunsaturated fatty acids (PUFAs) have been shown to play a key role in brain development and maintenance of neuronal homeostasis. PUFA’s exert their effects through modulating membrane fluidity, promoting neurite outgrowth, and impacting key membrane proteins. The main goal of my studies was to determine the effect of docosahexaenoic acid (DHA, 22:6 n-3), an omega 3 fatty acid) on the neuronal PMCA. SHSY5Y cells were differentiated by exposure to retinoic acid and treated with DHA (10 μM-50 μM) for 24 hours. The cells were assessed for viability by flow cytometry using propidium iodide. PMCA activity was measured by monitoring Ca2+- dependent ATP hydrolysis and PMCA protein levels were determined by immunoblotting. Our results show that exposure to DHA had no effect on cell viability (n=3). DHA stimulated PMCA activity in a dose-dependent manner with a 3-4 fold increase observed at 50 μM DHA (n=5). DHA also increased PMCA protein levels (n=4). Our results are the first to demonstrate potential protection of PMCA by PUFAs such as DHA. Ongoing studies are designed to investigate the mechanisms underlying PMCA stimulation. Boosting PMCA with PUFAs would preserve calcium homeostasis and protect against neuronal cell death in aging and neurodegeneration.
Senatus R, Zaidi A, Sarsour E. Rescuing Calcium Homeostasis with a Little Oil. Free Radical Biology and Medicine. 2022; 180(S1).