LAUSR

Significance Sphingolipids and cholesterol are important constituents of membranes. Very little is known how their metabolism is cross-regulated and how this affects membrane contact sites (MCS) that control lipid traffic. Here, we report deletion of sphingosine kinases (SphKs) that decreases S1P with concomitant increases in its precursors sphingosine and ceramide, reduced endoplasmic reticulum (ER) contacts with late endocytic organelles leading to accumulation of free cholesterol there. Surprisingly however, cholesterol transport to the ER was not reduced as deletion of SphKs promoted recruitment of cholesterol transfer protein Aster-B to the plasma membrane (PM) to facilitate transfer of cholesterol from the PM to the ER. Thus, SphKs and sphingolipid metabolites govern diverse MCS with the ER to control the movement of cholesterol between distinct cell membranes.