Sphingolipid-induced nutrient transporter loss: understanding the mechanism

University Of California-Irvine, Irvine CA

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Abstract

? DESCRIPTION (provided by applicant): Many forms of cellular stress, including inflammatory cytokines and cancer chemotherapeutics, cause ceramide accumulation. Although disruptions in sphingolipid metabolism are associated with numerous diseases, how ceramide controls cell survival, proliferation, and differentiation is incompletely understood. Recently, it has been shown that ceramide and related sphingolipids trigger amino acid and glucose transporter internalization producing bioenergetic stress that leads to quiescence in normal cells and cell death in constitutively anabolic cancer cells. Whether sphingolipid treatment induces nutrient transporter loss through changes in transporter synthesis, degradation, internalization, or recycling is not yet known. This study will investigate the molecular mechanisms behind sphingolipid-induced nutrient transporter loss and determine the role they play in sphingolipid-induced cell death with implications for the development of new therapeutic approaches. Aim 1 will test the hypothesis that sphingolipids increase nutrient transporter internalization and decrease recycling without affecting their degradation or synthesis. Aim 2 will assess the relationship between Arf6 inactivation by sphingolipids and nutrient transporter loss and cell death. Aim 3 will evaluate whether an inhibitor of Arf6, SecinH3, and sphingolipid analogs synergistically kill cancer cells, how broadly active this combination is, and whether normal cells are more resistant than transformed cells to this combination. Successful completion of these Aims will clarify the mechanisms by which sphingolipids modulate cell growth and survival. This work will also provide insight into the pathogenesis of conditions where sphingolipid metabolism is disrupted such as cancer, diabetes, and heart disease, and may suggest novel approaches to therapy and avoiding drug resistance.