Roles of the mitochondrial fatty acid synthesis II (mtFASII) pathway in mitochondrial function and signaling

Abstract

Despite the presence of a cytosolic fatty acid synthesis pathway, mitochondria have retained their own means of creating fatty acids via the mitochondrial fatty acid synthesis (mtFASII) pathway. The reason for its conservation has not yet been elucidated. Therefore, to better understand the role of mtFASII in the cell, we used a variety of methods to characterize the consequences of changes in mtFASII functionality in whole cells, isolated mitochondria, and mitochondrial secretions. We altered mtFASII functionality by knockdown of acyl carrier protein (ACP) or overexpression of mitochondrial trans-2-enoyl-CoA reductase (MECR). As a control for known respiratory deficits in mtFASII knockdowns, we also knocked down a component of complex I of the electron transport chain. We found that loss of mtFASII function disturbs metabolism and bioactive lipid regulation at the whole-cell and mitochondrial levels. We found that the mitochondrial secretome may contain bioactive lipids and small peptides, and that knockdown of the mtFASII pathway results in increased levels of dipeptides, among other metabolites, in the mitochondrial secretome. These data indicate that the mtFASII pathway may have a role in mitochondrial signaling in a manner not linked to mtFASII’s effects on the electron transport chain.