Palmitate-induced oxidative and conformational perturbations of SERCA impair Ca²⁺-ATPase activity and β-cell function

Palmitate-induced lipotoxicity contributes to pancreatic β-cell dysfunction, but the underlying molecular mechanisms remain incompletely understood. Because sarco/endoplasmic reticulum Ca²⁺-ATPase (SERCA) is essential for Ca²⁺ homeostasis and β-cell function, we investigated whether palmitate affects SERCA activity through oxidative and structural perturbations. To model lipotoxic stress and explore a potential mechanism of β-cell injury, SERCA1a-enriched sarcoplasmic reticulum vesicles were exposed to palmitate to examine its effects on pump activity and oxidative/structural changes. We found that palmitate caused a concentration-dependent inhibition of enzyme activity accompanied by changes in thiol accessibility, protein carbonylation, lipid peroxidation, and altered fluorescence signals consistent with perturbation of the transmembrane region of SERCA1a. These effects closely paralleled the loss of Ca²⁺-ATPase function. In INS-1E β-cells, palmitate reduced viability, induced apoptosis, impaired glucose-stimulated insulin secretion, and decreased SERCA2b expression. Together, these findings identify SERCA as a target of palmitate-induced lipotoxic injury and support a model in which SERCA dysfunction may contribute to β-cell failure under lipotoxic conditions.