Long-term effect of cyclic AMP on N-glycosylation is caused by an increase in the activity of the <i>cis</i>-prenyltransferase

Konrad, Matthias; Merz, Wolfgang E.

doi:10.1042/bj3160575

Cited by 16 publications

(7 citation statements)

References 49 publications

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“…Similarly, the adenylate cyclase activator forskolin [40] increased surface expression of CD59 as well. This was in accordance with the notion that high levels of cyclic AMP lead to higher activity of DHDDS and thus increased Dol levels [41,42].…”

Section: Therapeutics Targeting Dolicholsupporting

confidence: 92%

Regulation of dolichol-linked glycosylation

Welti

2012

Glycoconj J

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In the majority of congenital disorders of glycosylation, the assembly of the glycan precursor GlcNAc2Man9Glc3 on the polyprenol carrier dolichyl-pyrophosphate is compromised. Because N-linked glycosylation is essential to life, most types of congenital disorders of glycosylation represent partial losses of enzymatic activity. Consequently, increased availability of substrates along the glycosylation pathway can be beneficial to increase product formation by the compromised enzymes. Recently, we showed that increased dolichol availability and improved N-linked glycosylation can be achieved by inhibition of squalene biosynthesis. This review summarizes the current knowledge on the biosynthesis of dolichol-linked glycans with respect to deficiencies in N-linked glycosylation. Additionally, perspectives on therapeutic treatments targeting dolichol and dolichol-linked glycan biosynthesis are examined

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Section: Therapeutics Targeting Dolicholsupporting

confidence: 92%

Regulation of dolichol-linked glycosylation

Welti

2012

Glycoconj J

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“…De novo biosynthesis is initiated by the sequential addition of 12-17 isoprene units from isopentenyl pyrophosphate to farnesyl pyrophosphate catalyzed by ER-associated cis-isoprenyltransferases. The elongation stage is a key rate-controlling event in Dol-P synthesis Konrad and Merz, 1996). In the current view of the pathway the long-chain allylic pyrophosphate intermediate is then dephosphorylated, presumably on the cytoplasmic surface of the ER.…”

Section: Discussionmentioning

confidence: 99%

Expression and characterization of a human cDNA that complements the temperature-sensitive defect in dolichol kinase activity in the yeast sec59-1 mutant: the enzymatic phosphorylation of dolichol and diacylglycerol are catalyzed by separate CTP-mediated kinase activities in Saccharomyces cerevisiae

Fernández¹,

Shridas²,

Jiang³

et al. 2002

Glycobiology

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Dolichol kinase (DK) catalyzes the CTP-mediated phosphorylation of dolichol in eukaryotic cells, the terminal step in dolichyl monophosphate (Dol-P) biosynthesis de novo. In S. cerevisiae, the SEC59 gene encodes a protein essential for the expression of DK, an enzyme activity that is required for cell viability and normal rates of lipid intermediate synthesis and protein N-glycosylation. This study identifies a cDNA clone from human brain that encodes the mammalian homolog of DK (hDK1p). hDK1 is capable of complementing the growth defect, elevating DK activity, and consequently increasing Dol-P levels in vivo and restoring normal N-glycosylation of carboxypeptidase Y at the restrictive temperature in the temperature-sensitive mutant sec59-1. The CTP-mediated phosphorylation of diacylglycerol (DAG) is unaffected by either the temperature-sensitive mutation in the sec59-1 strain, overexpression of the SEC59 gene, or the mammalian homolog hDK1 under conditions that produced a loss or elevation in the level of DK activity. Additionally, overexpression of hDK1p in Sf-9 cells resulted in a 15-fold increase in DK activity but not DAG kinase activity in crude microsomal fractions. The cloned cDNA contains an open reading frame that would encode a protein with 538 amino acids and a molecular weight of 59,268 kDa. Consistent with this prediction, new polypeptides were detected with an apparent molecular weight of 59-60 kDa when His(6)-tagged constructs of hDK1 or the SEC59 gene were expressed in Sf-9 cells or the temperature-sensitive sec59-1 mutant cells, respectively. These results identify the first cDNA clone encoding a protein required for the expression of DK activity, possibly the catalytic subunit, in a mammalian cell, and establish that the phosphorylation of dolichol and DAG are catalyzed by separate kinase activities in yeast.

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“…Regulation of glycosylation can be tested with activators and inhibitors. Cyclic adenosine monophosphate (cAMP) has been shown to increase N-glycosylation capacity due to enlargement of the dolichol pyrophosphoryl oligosaccharide [ 20 – 22 ]. In contrast, tunicamycin completely blocks protein glycosylation by inhibition of the formation of N-acetylglucosamine-lipid intermediates [ 23 – 26 ], which results in decreased activity of membrane transporters because the membrane proteins remain localized in intracellular compartments due to decreased translocation to the cell surface membrane [ 27 ].…”

Section: Introductionmentioning

confidence: 99%

Glycosylation of Sodium/Iodide Symporter (NIS) Regulates Its Membrane Translocation and Radioiodine Uptake

et al. 2015

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PurposeHuman sodium/iodide symporter (hNIS) protein is a membrane glycoprotein that transports iodide ions into thyroid cells. The function of this membrane protein is closely regulated by post-translational glycosylation. In this study, we measured glycosylation-mediated changes in subcellular location of hNIS and its function of iodine uptake.MethodsHeLa cells were stably transfected with hNIS/tdTomato fusion gene in order to monitor the expression of hNIS. Cellular localization of hNIS was visualized by confocal microscopy of the red fluorescence of tdTomato. The expression of hNIS was evaluated by RT-PCR and immunoblot analysis. Functional activity of hNIS was estimated by radioiodine uptake. Cyclic AMP (cAMP) and tunicamycin were used to stimulate and inhibit glycosylation, respectively. In vivo images were obtained using a Maestro fluorescence imaging system.ResultscAMP-mediated Glycosylation of NIS resulted in increased expression of hNIS, stimulating membrane translocation, and enhanced radioiodine uptake. In contrast, inhibition of glycosylation by treatment with tunicamycin dramatically reduced membrane translocation of intracellular hNIS, resulting in reduced radioiodine uptake. In addition, our hNIS/tdTomato fusion reporter successfully visualized cAMP-induced hNIS expression in xenografted tumors from mouse model.ConclusionsThese findings clearly reveal that the membrane localization of hNIS and its function of iodine uptake are glycosylation-dependent, as our results highlight enhancement of NIS expression and glycosylation with subsequent membrane localization after cAMP treatment. Therefore, enhancing functional NIS by the increasing level of glycosylation may be suggested as a promising therapeutic strategy for cancer patients who show refractory response to conventional radioiodine treatment.

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Long-term effect of cyclic AMP on N-glycosylation is caused by an increase in the activity of the cis-prenyltransferase

Cited by 16 publications

References 49 publications

Regulation of dolichol-linked glycosylation

Regulation of dolichol-linked glycosylation

Expression and characterization of a human cDNA that complements the temperature-sensitive defect in dolichol kinase activity in the yeast sec59-1 mutant: the enzymatic phosphorylation of dolichol and diacylglycerol are catalyzed by separate CTP-mediated kinase activities in Saccharomyces cerevisiae

Glycosylation of Sodium/Iodide Symporter (NIS) Regulates Its Membrane Translocation and Radioiodine Uptake

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