Lactacystin increases LDL receptor level on HepG2 cells.

Low density lipoprotein (LDL) receptor expression is regulated by proteolysis of transcription factors, sterol regulatory element binding proteins. To investigate the involvement of proteasome in this regulatory process, the effect of lactacystin, a specific proteasome inhibiton of microbial origin, was tested on LDL receptor expression on HepG2 cells. The addition of lactacystin to the cell culture increased the number of LDL receptors, indicating that proteasome plays a down-regulatory role in LDL receptor expression.