Evidence of gene amplification in tunicamycin-resistant chinese hamster ovary cells

Scocca, Jane R.; Hartog, K.; Krag, Sharon S.

doi:10.1016/s0006-291x(88)80740-x

Cited by 11 publications

(4 citation statements)

References 17 publications

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“…The detection of this compensatory (possibly exemplary) backup mechanism can be interpreted as a sign of the vital importance of maintaining correct processing of N-glycans. This view is corroborated by independent experience with (i) glycosylation inhibitors such as swainsonine from plants of the genus Swainsona, which cause a disease known as locoism [530], or tunicamycin whose deadly effects due to blocking Nglycosylation at the first step of the dolichol cycle, that is the formation of Dol-P-P-GlcNAc, are counterbalanced by gene amplification [531] as well as (ii) with deliberately engineered loss-of-function mutants after altering a glycosyltransferase gene in the mouse genome [463,532,533]. Knockout mice with gene disruption in N-acetylglucosaminyltransferase I, which effectively reduces glycosylation to a 'yeast-or insect-like' status, are invariably subject to embryonic lethality, although mutant cells in vitro suffer no overt consequences [463,532,533].…”

Section: Review Articlementioning

confidence: 83%

Eukaryotic glycosylation: whim of nature or multipurpose tool?

Reuter¹,

Gabius²

1999

Cellular and Molecular Life Sciences (CMLS)

214

141

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Protein and lipid glycosylation is a ubiquitous phenomenon. The task of cataloguing the great structural variety of the glycan part has demanded considerable efforts over decades. This patient endeavor was imperative to discern the inherent rules of glycosylation which cannot affirm assumptions on a purely coincidental nature of this type of protein and lipid modification. These results together with theoretical considerations uncover a salient property of oligosaccharides. In comparison with amino acids and nucleotides, monosaccharides excel in their potential to serve as units of hardware for storing biological information. Thus, the view that glycan chains exclusively affect physiochemical properties of the conjugates is indubitably flawed. This original concept has been decisively jolted by the discovery of endogenous receptors (lectins) for distinct glycan epitopes which are as characteristic as a fingerprint or a signature for a certain protein (class) or cell type. Recent evidence documents that these binding proteins are even endowed with the capacity to select distinct low-energy conformers of the often rather flexible oligosaccharides, granting entry to a new level of regulation of ligand affinity by shifting conformer equilibria. The assessment of the details of this recognition by X-ray crystallography, nuclear magnetic resonance spectroscopy, microcalorimetry and custom-made derivatives is supposed to justify a guarded optimism in satisfying the need for innovative drug design in antiadhesion therapy, for example against viral or bacterial infections and unwanted inflammation. This review presents a survey of the structural aspects of glycosylation and of evidence to poignantly endorse the notion that carrier-attached glycan chains can partake in biological information transfer at the level of cell compartments, cells and organs.

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Section: Review Articlementioning

confidence: 83%

Eukaryotic glycosylation: whim of nature or multipurpose tool?

Reuter¹,

Gabius²

1999

Cellular and Molecular Life Sciences (CMLS)

214

141

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“…In most species, this enzyme is the first step in the dolichol pathway for protein N-glycosylation. In other systems, TUN resistance results from altered uptake, structural alterations, or amplifications of the glycosyltransferase (68,74,99,108). Although the first two mech anisms have not been tested in Leishmania spp., every TUN-resistant line of Leishmania obtained thus far contains a DNA amplification and elevated levels of a TUN-sensitive glycosyl transferase activity, regardless of whether mutagenesis was included in the selection process (32, 63,65,86).…”

Section: Tunicamycin and Glycosyltransferasementioning

confidence: 99%

GENE AMPLIFICATION IN LEISHMANIA

Beverley

1991

Annu. Rev. Microbiol.

215

128

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“…As mentioned earlier, CHO-K1 cells resistant to toxic concentrations of TN can be isolated without prior intentional mutagenesis due to spontaneous amplification of a chromosomal region including the GPT locus, resulting in increased GPT gene expression (Scocca et al 1988;Zhu and Lehrman 1989).…”

Section: Discussionmentioning

confidence: 99%

Unexpected Basis for Impaired Glc3Man9GlcNAc2-P-P-Dolichol Biosynthesis by Elevated Expression of GlcNAc-1-P Transferase

Gao

Shang

Lehrman³

2007

Glycobiology

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GlcNAc-1-P transferase (GPT) transfers GlcNAc-1-P from UDP-GlcNAc to dolichol-P (Dol-P), forming GlcNAc-P-PDol to initiate synthesis of the lipid-linked oligosaccharide Glc3Man9GlcNAc2-P-P-dolichol (G3M9Gn2-P-P-Dol). Elevated expression of GPT in CHO-K1 cells is known to cause accumulation of the intermediate M5Gn2-P-P-Dol, presumably by excessively consuming Dol-P and thereby hindering Dol-P-dependent synthesis of Man-P-Dol (MPD) and Glc-P-Dol (GPD), which provide the residues for extending M5Gn2-P-P-Dol to G3M9Gn2-P-P-Dol. If so, elevated GPT expression should increase oligosaccharide-P-P-Dol quantities and reduce monosaccharide-P-Dol quantities, while requiring GPT enzymatic activity. Here we report that elevated GPT expression failed to appreciably alter the quantities of the two classes of dolichol-linked saccharide, and that neither a GPT inhibitor nor introduction of an inactivating mutation into GPT prevented M5Gn2-P-P-Dol accumulation,arguing against excessive Dol-P consumption. Unexpectedly,we noticed similarities between the phenotypes of GPT overexpressers and of CHO-K1 cells lacking Lec35p (encoded by MPDU1, the congenital disorder of glycosylation(CDG)-If locus), which is required for utilization of MPD and GPD. By compensatory overexpression of Lec35p, G3M9Gn2-P-P-Dol synthesis in GPT overexpressers could be restored. However, GPT overexpression did not affect the levels of Lec35 mRNA or protein. These results suggest that GPT may impair Lec35p function, and imply that upper as well as lower limits on GPT expression exist in normal cells. Since the mammalian GPT gene can undergo spontaneous amplification, the data also indicate a potential basis for forms of pseudo-CDG-If.

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Evidence of gene amplification in tunicamycin-resistant chinese hamster ovary cells

Cited by 11 publications

References 17 publications

Eukaryotic glycosylation: whim of nature or multipurpose tool?

Eukaryotic glycosylation: whim of nature or multipurpose tool?

GENE AMPLIFICATION IN LEISHMANIA

Unexpected Basis for Impaired Glc3Man9GlcNAc2-P-P-Dolichol Biosynthesis by Elevated Expression of GlcNAc-1-P Transferase

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