[HTML][HTML] ER calcium release promotes mitochondrial dysfunction and hepatic cell lipotoxicity in response to palmitate overload

RA Egnatchik, AK Leamy, DA Jacobson, M Shiota… - Molecular …, 2014 - Elsevier
RA Egnatchik, AK Leamy, DA Jacobson, M Shiota, JD Young
Molecular metabolism, 2014Elsevier
Palmitate overload induces hepatic cell dysfunction characterized by enhanced apoptosis
and altered citric acid cycle (CAC) metabolism; however, the mechanism of how this occurs
is incompletely understood. We hypothesize that elevated doses of palmitate disrupt
intracellular calcium homeostasis resulting in a net flux of calcium from the ER to
mitochondria, activating aberrant oxidative metabolism. We treated primary hepatocytes and
H4IIEC3 cells with palmitate and calcium chelators to identify the roles of intracellular …
Abstract
Palmitate overload induces hepatic cell dysfunction characterized by enhanced apoptosis and altered citric acid cycle (CAC) metabolism; however, the mechanism of how this occurs is incompletely understood. We hypothesize that elevated doses of palmitate disrupt intracellular calcium homeostasis resulting in a net flux of calcium from the ER to mitochondria, activating aberrant oxidative metabolism. We treated primary hepatocytes and H4IIEC3 cells with palmitate and calcium chelators to identify the roles of intracellular calcium flux in lipotoxicity. We then applied 13C metabolic flux analysis (MFA) to determine the impact of calcium in promoting palmitate-stimulated mitochondrial alterations. Co-treatment with the calcium-specific chelator BAPTA resulted in a suppression of markers for apoptosis and oxygen consumption. Additionally, 13C MFA revealed that BAPTA co-treated cells had reduced CAC fluxes compared to cells treated with palmitate alone. Our results demonstrate that palmitate-induced lipoapoptosis is dependent on calcium-stimulated mitochondrial activation, which induces oxidative stress.
Elsevier