The human cholesterogenic enzymes DHCR14 and LBR are differentially regulated transcriptionally and post-translationally

ABSTRACT: Cholesterol synthesis is a tightly regulated process, both transcriptionally and post-translationally. Transcriptional control of cholesterol synthesis is relatively well understood. However, of the ~20 enzymes in cholesterol biosynthesis, post-translational regulation has only been examined for a small number. Three of the four sterol reductases, DHCR7, DHCR14 and LBR, share evolutionary ties with a high level of sequence homology and predicted structural homology. Despite their homology and that they uniquely share the same 14 reductase activity in cholesterol biosynthesis, little is known about the post-translational regulation of DHCR14 and LBR. Using CHO-7 cells stably expressing epitope tagged DHCR14 or LBR we investigated the post-translational regulation of these enzymes. We found that DHCR14 and LBR undergo differential post translational regulation, with DHCR14 being rapidly turned over, triggered by cholesterol and other sterol intermediates while LBR remained stable. DHCR14 is degraded via the ubiquitin-proteasome system and we identified several DHCR14 and DHCR7 putative interaction partners including the E3 ligase WWP2, which plays a role in the basal and cholesterol-mediated regulation of DHCR14. Interestingly, we found that gene expression across an array of human tissues showed that the C14-SRs gene expression is negatively related; one enzyme or the other tends to be predominately expressed in each tissue. Overall, our findings indicate that while LBR tends to be the constitutively active C14-SR, DHCR14 levels are tuneable, responding to the local cellular demands for cholesterol.

INSTRUMENT(S): Orbitrap Fusion Lumos, LTQ Orbitrap Velos

ORGANISM(S): Homo Sapiens (human) Cricetulus Griseus (chinese Hamster) (cricetulus Barabensis Griseus)

TISSUE(S): Cell Culture

SUBMITTER: Gene Hart-Smith  

LAB HEAD: Andrew J Brown

PROVIDER: PXD016417 | Pride | 2020-01-15

REPOSITORIES: Pride