Impact of natural flavonoid gossypin on P-ATPases: a potential selective inhibitor of the Plasma Membrane Ca2+-ATPase

ONTIVEROS MQ; TOMISAKI M; LORI F; CERF NT; MONTES MR; ROSSI RC; ROSSI JPFC; FERREIRA GOMES MS

Córdoba, Provincia de Córdoba, Argentina

Congreso; LI Reunión Anual de la Sociedad Argentina de Biofísica; 2023

Sociedad Argentina de Biofísica

Flavonoids are multi-targeted compounds with antioxidant, anti-inflammatory, and anticancer effects, as well as the ability to modulate the essential functions of cellular enzymes, including P-ATPase [1]. In our laboratory, we studied the effect of flavonoids on plasma membrane calcium ATPase (PMCA4), a calmodulin-regulated P-ATPase that maintains intracellular Ca2+ homeostasis and links Ca2+ transport to ATP hydrolysis in eukaryotic cells [2]. The importance of finding specific inhibitors is that it is essential to understand the importance of an enzyme in many biological processes; since specific and potent inhibitors of PMCA4 do not exist yet, we have investigated several P-ATPases and analyzed different flavonoids as inhibitors. We found that some flavonoids such as quercetin and gossypin (gossypetin-8-Oglucoside) inhibited PMCA4 activity. However, gossypin appeared as a potent inhibitor of PMCA4 activity (Ki = 5 μM). In a previous publication, we showed that gossypin inhibits PMCA4 via a gossypin -Mg2+ complex. We then tested the specificity of gossypin against other major P-ATPases. We found that gossypin had little or no inhibitor effect on sarco/endoplasmic Ca2+-ATPase (SERCA), Na+/K+-ATPase, Mg2+-ATPase, and gastric H+/K+-ATPase, suggesting that it is probably specific for PMCA4. By using gossypin it was then possible to estimate the activity of PMCA4 in a complex system with the contribution of ATPase activity from other ATPases present in a microsome sample obtained from sf9 cells that overexpress human isoform 4b. In conclusion, these results indicate that gossypin is a potential candidate to be a specific inhibitor, opening to use as a tool to identify the role of PMCA4 in complex systems.References[1] Song et al. (2023). Chemical biology & drug design, 101(1), 131-137.[2] Ontiveros et al. (2019). Biochemical pharmacology, 166, 1-11.