Geranylgeraniol promotes entry of UT-2 cells into the cell cycle in the absence of mevalonate.
Although UT-2 cells, a mutant clone of Chinese hamster ovary cells, have been shown to require mevalonate for growth due to a deficiency in 3-hydroxy-3-methylglutaryl-CoA reductase, the precise mevalonate-derived product(s) essential for proliferation has not been identified. These studies show that UT-2 cells proliferate in the presence of free geranylgeraniol (GG-OH), as well as mevalonate. Cell growth was optimal when the culture medium was supplemented with 5-10 microM GG-OH. Under these growth conditions [3H]GG-OH is actively incorporated into UT-2 proteins. Prominent [3H]geranylgeranylated polypeptides in the size range (19-27 kDa) of the small GTP-binding proteins are observed by SDS-PAGE. Analysis of the butanol-soluble products released from the metabolically labeled proteins by digestion with Pronase E reveals that the proteins contain [3H]geranylgeranylated cysteine residues. Even though [3H]farnesol is also incorporated into cysteinyl residues of a different set of UT-2 proteins, farnesol added at 10 microM did not satisfy the mevalonate requirement for cell growth. These results show that UT-2 cells divide in the presence of exogenously supplied GG-OH, providing evidence that one or more geranylgeranylated proteins are essential for entry of UT-2 cells, and probably other mammalian cells, into the cell cycle.
Crick
D C
DC
Department of Biochemistry, University of Kentucky College of Medicine, Lexington 40536.
Andres
D A
DA
Waechter
C J
CJ
D000818:Animals; D016466:CHO Cells / Q000187:drug effects*; D002453:Cell Cycle / Q000187:drug effects*; D006224:Cricetinae; D003412:Cricetulus; D004224:Diterpenes / Q000494:pharmacology*; D005204:Farnesol / Q000494:pharmacology; D006903:Hydroxymethylglutaryl CoA Reductases / Q000172:deficiency; D008798:Mevalonic Acid / Q000378:metabolism*; D017368:Protein Prenylation / Q000187:drug effects; D011499:Protein Processing, Post-Translational / Q000187:drug effects; D016196:S Phase / Q000187:drug effects
D004224:Diterpenes; D005204:Farnesol; C017338:geranylgeraniol; D006903:Hydroxymethylglutaryl CoA Reductases; D008798:Mevalonic Acid