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The prenyltransferase UBIAD1 is the target of geranylgeraniol in degradation of HMG CoA reductase.

Schumacher MM, Elsabrouty R, Seemann J, Jo Y, DeBose-Boyd RA - Elife (2015)

Bottom Line: Here, we show that sterols stimulate binding of UBIAD1 to the cholesterol biosynthetic enzyme HMG CoA reductase, which is subject to sterol-accelerated, endoplasmic reticulum (ER)-associated degradation augmented by the nonsterol isoprenoid geranylgeraniol through an unknown mechanism.CRISPR-CAS9-mediated knockout of UBIAD1 relieves the geranylgeraniol requirement for reductase degradation.The current results identify UBIAD1 as the elusive target of geranylgeraniol in reductase degradation, the inhibition of which may contribute to accumulation of cholesterol in SCD.

View Article: PubMed Central - PubMed

Affiliation: Department of Molecular Genetics, University of Texas Southwestern Medical Center, Dallas, United States.

ABSTRACT
Schnyder corneal dystrophy (SCD) is an autosomal dominant disorder in humans characterized by abnormal accumulation of cholesterol in the cornea. SCD-associated mutations have been identified in the gene encoding UBIAD1, a prenyltransferase that synthesizes vitamin K2. Here, we show that sterols stimulate binding of UBIAD1 to the cholesterol biosynthetic enzyme HMG CoA reductase, which is subject to sterol-accelerated, endoplasmic reticulum (ER)-associated degradation augmented by the nonsterol isoprenoid geranylgeraniol through an unknown mechanism. Geranylgeraniol inhibits binding of UBIAD1 to reductase, allowing its degradation and promoting transport of UBIAD1 from the ER to the Golgi. CRISPR-CAS9-mediated knockout of UBIAD1 relieves the geranylgeraniol requirement for reductase degradation. SCD-associated mutations in UBIAD1 block its displacement from reductase in the presence of geranylgeraniol, thereby preventing degradation of reductase. The current results identify UBIAD1 as the elusive target of geranylgeraniol in reductase degradation, the inhibition of which may contribute to accumulation of cholesterol in SCD.

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Subcellular localization of wild type and SCD-associated N102S UBIAD1 in transfected SV-589 cells.SV-589 cells were set up for experiments on day 0, transfected on day 1 with pCMV-Myc-UBIAD1 (WT) or (N102S) in medium A containing 10% FCS, and subjected to immunostaining, followed by imaging as described in the legend to Figure 5—figure supplement 1.DOI:http://dx.doi.org/10.7554/eLife.05560.018
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fig8s2: Subcellular localization of wild type and SCD-associated N102S UBIAD1 in transfected SV-589 cells.SV-589 cells were set up for experiments on day 0, transfected on day 1 with pCMV-Myc-UBIAD1 (WT) or (N102S) in medium A containing 10% FCS, and subjected to immunostaining, followed by imaging as described in the legend to Figure 5—figure supplement 1.DOI:http://dx.doi.org/10.7554/eLife.05560.018

Mentions: In the experiment of Figure 8B, we used immunofluorescence to examine the subcellular localization of wild type and SCD-associated mutants of UBIAD1 in SV-589 cells grown in FCS-containing medium. The results show that wild type UBIAD1 localized to Golgi membranes that also stained with antibodies against GM130 (Figure 8B, panels 1–4). UBIAD1 (N102S) primarily exhibited a diffuse, reticular localization corresponding to ER membranes and little, if any, of the protein appeared in the Golgi (Figure 8B, panels 5–8). The repeat experiment shown in Figure 8—figure supplement 2 confirms that wild type UBIAD1 localized to the Golgi, whereas UBIAD1 (N102) primarily localized to ER membranes. Similar to the N102 mutant, UBIAD1 (G177R) was also primarily concentrated in membranes of the ER, but not the Golgi (Figure 8B, panels 9–12).


The prenyltransferase UBIAD1 is the target of geranylgeraniol in degradation of HMG CoA reductase.

Schumacher MM, Elsabrouty R, Seemann J, Jo Y, DeBose-Boyd RA - Elife (2015)

Subcellular localization of wild type and SCD-associated N102S UBIAD1 in transfected SV-589 cells.SV-589 cells were set up for experiments on day 0, transfected on day 1 with pCMV-Myc-UBIAD1 (WT) or (N102S) in medium A containing 10% FCS, and subjected to immunostaining, followed by imaging as described in the legend to Figure 5—figure supplement 1.DOI:http://dx.doi.org/10.7554/eLife.05560.018
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4374513&req=5

fig8s2: Subcellular localization of wild type and SCD-associated N102S UBIAD1 in transfected SV-589 cells.SV-589 cells were set up for experiments on day 0, transfected on day 1 with pCMV-Myc-UBIAD1 (WT) or (N102S) in medium A containing 10% FCS, and subjected to immunostaining, followed by imaging as described in the legend to Figure 5—figure supplement 1.DOI:http://dx.doi.org/10.7554/eLife.05560.018
Mentions: In the experiment of Figure 8B, we used immunofluorescence to examine the subcellular localization of wild type and SCD-associated mutants of UBIAD1 in SV-589 cells grown in FCS-containing medium. The results show that wild type UBIAD1 localized to Golgi membranes that also stained with antibodies against GM130 (Figure 8B, panels 1–4). UBIAD1 (N102S) primarily exhibited a diffuse, reticular localization corresponding to ER membranes and little, if any, of the protein appeared in the Golgi (Figure 8B, panels 5–8). The repeat experiment shown in Figure 8—figure supplement 2 confirms that wild type UBIAD1 localized to the Golgi, whereas UBIAD1 (N102) primarily localized to ER membranes. Similar to the N102 mutant, UBIAD1 (G177R) was also primarily concentrated in membranes of the ER, but not the Golgi (Figure 8B, panels 9–12).

Bottom Line: Here, we show that sterols stimulate binding of UBIAD1 to the cholesterol biosynthetic enzyme HMG CoA reductase, which is subject to sterol-accelerated, endoplasmic reticulum (ER)-associated degradation augmented by the nonsterol isoprenoid geranylgeraniol through an unknown mechanism.CRISPR-CAS9-mediated knockout of UBIAD1 relieves the geranylgeraniol requirement for reductase degradation.The current results identify UBIAD1 as the elusive target of geranylgeraniol in reductase degradation, the inhibition of which may contribute to accumulation of cholesterol in SCD.

View Article: PubMed Central - PubMed

Affiliation: Department of Molecular Genetics, University of Texas Southwestern Medical Center, Dallas, United States.

ABSTRACT
Schnyder corneal dystrophy (SCD) is an autosomal dominant disorder in humans characterized by abnormal accumulation of cholesterol in the cornea. SCD-associated mutations have been identified in the gene encoding UBIAD1, a prenyltransferase that synthesizes vitamin K2. Here, we show that sterols stimulate binding of UBIAD1 to the cholesterol biosynthetic enzyme HMG CoA reductase, which is subject to sterol-accelerated, endoplasmic reticulum (ER)-associated degradation augmented by the nonsterol isoprenoid geranylgeraniol through an unknown mechanism. Geranylgeraniol inhibits binding of UBIAD1 to reductase, allowing its degradation and promoting transport of UBIAD1 from the ER to the Golgi. CRISPR-CAS9-mediated knockout of UBIAD1 relieves the geranylgeraniol requirement for reductase degradation. SCD-associated mutations in UBIAD1 block its displacement from reductase in the presence of geranylgeraniol, thereby preventing degradation of reductase. The current results identify UBIAD1 as the elusive target of geranylgeraniol in reductase degradation, the inhibition of which may contribute to accumulation of cholesterol in SCD.

Show MeSH
Related in: MedlinePlus