Short communicationPhosphorylation regulates activity of 7-dehydrocholesterol reductase (DHCR7), a terminal enzyme of cholesterol synthesis

•Inhibition of AMPK or PKA decreases DHCR7 activity.•Mutation of S14 in DHCR7 decreases activity independently of AMPK and PKA.•In the skin, phosphorylation of DHCR7 may divert flux from cholesterol to vitamin D synthesis.

Cholesterol is essential for survival, but too much or too little can cause disease. Thus, cholesterol levels must be kept within close margins. 7-dehydrocholesterol reductase (DHCR7) is a terminal enzyme of cholesterol synthesis, and is essential for embryonic development. Largely, DHCR7 research is associated with the developmental disease Smith-Lemli-Opitz syndrome, which is caused by mutations in the DHCR7 gene. However, little is known about what regulates DHCR7 activity. Here we provide evidence that phosphorylation plays a role in controlling DHCR7 activity, which may provide a means to divert flux from cholesterol synthesis to vitamin D production. DHCR7 activity was significantly decreased when we used pharmacological inhibitors against two important kinases, AMP-activated protein kinase and protein kinase A. Moreover, mutating a known phosphorylated residue, S14, also decreased DHCR7 activity. Thus, we demonstrate that phosphorylation modulates DHCR7 activity in cells, and contributes to the overall synthesis of cholesterol, and probably vitamin D.