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PubMed1977

Mutants of mouse fibroblasts altered in the synthesis of cell surface glycoproteins. Preliminary evidence for a defect in the acetylation of glucosamine 6-phosphate.

We hve reported the isolation and preliminary biochemical characterization of two mutants of mouse fibroblasts selected for a decrease incell-to-substrate adhesion (Pouysségur, J., and Pastan, I. (1976) Proc. Natl. Acad. Sci. U.S.A. 73, 544-548). We attributed the adhesive defect of these mutants (AD6 and AD8) to the absence of iodinatable cell surface proteins. This study demonstrates that a defect in glycoprotein synthesis is the biochemical basis for the reduction in proteins exposed at the outer surface of the mutant cells. When D-glucosamine or L-fucose was used as radioactive precursor, analysis by sodium dodecyl sulfate-polyacrylamide gel electrophoresis revealed a decrease in the labeling of all the glycoproteins of both clones. This decrease in glycoprotein labeling was not due to a defect in D-glucosamine uptake, since this precursor was taken up at a higher rate in the mutants than in the wild type. In spite of this high uptake, the rate of D-glucosamine incorporation into macromolecules was decreased by 60% and the carbohydrate content of membranes (mannose, galactose, N-acetylglucosamine, N-acetylgalactosamine, and sialic acid) from clone AD6 was diminished by 40 to 60%. When the various cell lines were labeled for 1 to 3 h with glucosamine and the acid-soluble pool analyzed, the wild type cells were found to accumulate UDP-N-acetylhexosamine as the major component. In contrast, clones AD6 and AD8 accumulated glucosamine 6-phosphate as the major component. This last finding suggests that there is a block in the N-acetylation of glucosamine 6-phosphate in both instants. This suggestion is supported by the finding that feeding the mutant cells 10 mM N-acetylglucosamine reverts them to the wild type phenotype (Pouysségur, J., Willingham, M. and Pastan, I. (1977) Proc. Natl. Acad. Sci. U.S.A., in pressy. In wild type cells all of the iodinatable proteins of the cell surface have the same mobility as the glycoproteins when analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. We conclude that the early block in glycoprotein synthesis accounts for the reduction in iodinatable surface proteins in the mutant cells.

Acetyltransferases↗

PubMed1998

[Gonarthrosis--current aspects of therapy with glucosamine sulfate (dona200-S)].

For many years glucosamine sulfate has been successfully used in the therapy of osteoarthritis. Today's importance of the treatment with glucosamine sulfate is even increasing. Glucosamine sulfate meets all standards of an efficient and well tolerated drug. This is proven by experimental as well as clinical studies, in which glucosamine sulfate was tested in accordance with the current state of scientific research. The results show that glucosamine sulfate will lead to long-lasting pain reduction and functional improvement by means of increasing anabolical mechanisms, reducing the activity of proteolytic enzymes and by its antiinflammatory effect. Since this therapeutical effect is not due to an inhibition of the prostaglandin synthesis, treatment is not accompanied by the known unwanted side effects. Glucosamine sulfate is very well tolerated by patients of all ages under short-term as well as long-term treatment.

Arthritis↗

PubMed1977

Developmental defects associated with glucosamine auxotrophy in Saccharomyces cerevisiae.

Saccharomyces cerevisiae mutants, unable to make D-glucosamine owing to a defect in the enzyme 2-amino-2-deoxy-D-glucose-6-phosphate ketol-isomerase (amino-transferring) (EC 5.3.1.19), show aberrations both in sporulation and in vegetative growth. They grow normally on a medium of yeast extract, peptone, and dextrose (YEPD) containing D-glucosamine (1 mg/ml), and such cells accumulate 4 to 5 times the amount of D-glucosamine present in wild-type cells cultured on YEPD alone. When such mutant cells are shifted to YEPD alone, they continue to increase in cell mass for about 10 hr (three to four cell cycles) and produce strings of beads in which the cells fail to separate. Although each of the "cells" contains a nucleus, electron micrographs of thin sections reveal that septation is defective apparently owing to the inability to synthesize chitin, which forms the primary septum in S. cerevisiae. The viability of such cultures drops rapidly after 3-5 hr, a fact attributable to lysis of the cells through wall defects in the septum region where gross disorganization is apparent. When the mutant cells grown on YEPD plus D-glucosamine are transferred to sporulation medium (1% potassium acetate), they proceed through meiosis to produce viable spores that appear to be altered only in the nature of the spore wall. The spores lack a dark-staining surface layer that is visible in thin sections prepared from wild-type cells, they are notably less hydrophobic than wild-type spores, and they are digested and lysed by glucanases that do not affect normal spores. All of these properties suggest that D-glucosamine is required for spore maturation and is used to synthesize a glucanase-resistant hydrophobic surface layer on the primary glucan spore wall. In agreement with this postulate, D-glucosamine synthesis and the activity of the isomerase do not appear until late in meiosis when tetranucleate cells are abundantly present in the sporulation culture.

Journal Article↗

PubMed2004

In vitro effects of poly-N-acetyl glucosamine on the activation of platelets in platelet-rich plasma with and without red blood cells.

BACKGROUND: This study was performed to assess the effect of poly-N-acetyl glucosamine fiber slurry on plasma clotting proteins, platelets, and red blood cells in the clotting of the blood. METHODS: Citrate phosphate dextrose whole blood was stored at 22degreesC for 48 hours to prepare platelet-poor plasma, platelet-rich plasma (PRP), and PRP plus red blood cells with hematocrit values of 20%, 35%, and 45% with and without an equal volume of poly-N-acetyl glucosamine fibers (1 mg/mL 0.9% NaCl). RESULTS: Thromboelastogram data show that poly-N-acetyl glucosamine fibers (p-GlcNAc) significantly reduced the R time in platelet-poor plasma, PRP, and PRP supplemented with red blood cells. Poly-N-acetyl glucosamine fibers increased, but not significantly, Annexin V and factor X binding to platelets, platelet microparticles, and red blood cell Annexin V binding. Poly-N-acetyl glucosamine fibers increased the production of thromboxane B2 by PRP. CONCLUSION: Poly-N-acetyl glucosamine slurry activates platelets.

Acetylglucosamine↗

PubMed1973

Isolation and Characterization of Glucosamine-containing Storage Glycoproteins from the Cotyledons of Phaseolus aureus.

Cotyledons of Phaseolus aureus contain protein-bound glucosamine which is metabolized during germination. The glucosamine is present in storage glycoproteins, and these are concurrently metabolized along with the glucosamine. These glycoproteins are associated with protein bodies. Characterization of the glucosamine-containing storage proteins showed them to be identical with vicilin and legumin, the major storage proteins of the Leguminosae. Phaseolus aureus vicilin has a sedimentation constant of 8.0S and is made up of four nonidentical subunits. It contains 0.2% glucosamine and 1% mannose. Legumin has a sedimentation constant of 11.3S and is made up of three nonidentical subunits. It contains about 0.1% glucosamine.

Journal Article↗

PubMed2001

A review of articular cartilage pathology and the use of glucosamine sulfate.

OBJECTIVE: To refresh the athletic trainer's knowledge of articular cartilage biomechanics, physiology, and structure and explore the role of glucosamine sulfate in treating articular cartilage pathologic conditions, including supplementation methods and clinical outcomes. DATA SOURCES: We searched MEDLINE from 1989 through 2000 and SPORT Discus from 1975 through 2000 using the following key words: glucosamine sulfate, articular cartilage, osteoarthritis, and proteoglycans. DATA SYNTHESIS: Articular cartilage functions as a wear-resistant, smooth, nearly frictionless, load-bearing surface. Glucosamine sulfate can be thought of as a building block that helps restore the proteoglycan-rich extracellular matrix and thus balance articular cartilage catabolism and anabolism. Beneficial clinical effects of glucosamine sulfate in the osteoarthritic population have been documented. However, the use of glucosamine sulfate for athletic articular cartilage injuries is unproved. CONCLUSIONS/RECOMMENDATIONS: Clinical studies indicate that glucosamine sulfate has been shown to be a safe and relatively effective treatment for osteoarthritis. However, no evidence to date supports or refutes a carryover effect to the athletic population and the injuries that occur in sport.

Journal Article↗

PubMed2026

Flux rewiring enables native D-glucosamine production in Escherichia coli.

D-Glucosamine is an industrially important amino sugar used in pharmaceuticals, nutraceuticals, and functional materials, yet its production remains dominated by chemical extraction from chitinous biomass, raising sustainability and allergen concerns. Escherichia coli natively synthesizes D-glucosamine directly from D-glucose through endogenous metabolism, revealing an underutilized amino sugar biosynthetic capability. Building on this native pathway, D-glucosamine production was enhanced through targeted genetic modifications and systematic optimization of nitrogen metabolism and cultivation conditions, reaching 9.2 g L-1 under shake-flask conditions. This work extends a phosphorylation-dephosphorylation strategy previously developed for neutral rare sugars to amino sugar biosynthesis, demonstrating the broader applicability of this metabolic design principle. Phosphatase identity emerged as a key control point for product formation: YbiV was the most effective phosphatase for selective D-glucosamine production, whereas alternative phosphatases redirected flux toward D-sedoheptulose. This enzyme-dependent flux partitioning further enabled tunable co-production of D-glucosamine and D-sedoheptulose. Native amino sugar biosynthesis in E. coli provides a controllable framework for producing chemically distinct sugars through endogenous metabolism and establishes a generalizable strategy for engineering amino sugar and other nitrogen-containing metabolite biosynthesis.

Escherichia coli↗

PubMed1975

Incorporation of fucose and glucosamine into cell bound and medium released macromolecules.

(1) Determinations were carried out on the incorporation of fucose-6-(3H) and glucosamine-6-(3H) into trichloracetic acid insoluble macromolecules which remained bound to the cells or were released into the medium of chick embryo muscle cell cultures. The radioactivity determined in the medium was corrected for unspecific binding of label to components of the medium. (2) During an incorporation period of six hours the incorporation per microgram DNA with fucose as label into cell bound macromolecules is about twice as high as the incorporation into macromolecules released into medium. With glucosamine about twice as much is incorporated into medium released into the cell bound macromolecules. (3) The incorporation per microgram DNA increased during a culture period of three days but the increase ceases at different times during this culture period when determined with fucose or glucosamine or for cell bound and medium released material. (4) An increase in cell density increases the incorporation per DNA of fucose and to a much slighter extent that of glucosamine. Reduction of cell density by addition of cytosine arabinoside to the medium does not increase the incorporation per microgram DNA. (5) The effect of changes of fibroblast/myoblast ratios on the incorporation of fucose and glucosamine were examined. No significant effect was observed for a ratio of 10-30% fibroblasts when control cultures or cultures after cell sedimentation were maintained in complete medium. Marked changes were observed after culture in medium without protein components. Under these conditions an increase in the fibroblast/myoblast ratios were observed as well as an increase in the incorporation of label into medium released and a decrease into cell bound macromolecules.

Animals↗

PubMed1993

Sugar-binding sites with specificity for glucosamine in the guinea pig middle ear mucosa.

Glucosamine-binding sites were detected in Lowicryl K4M-embedded guinea pig middle ear mucosa by electron microscopy, using glucosaminyl bovine serum albumin. Incubation of ultrathin tissue sections with gold-labeled glucosaminyl bovine serum albumin (GlcN/BSA/gold) resulted in binding mainly on cilia, microvilli, rough endoplasmic reticulum and nuclei. The sugar binding was not inhibited after ultrathin sections had been digested with trypsin or neuraminidase. Various carbohydrates and glycoconjugates were tested as competitive inhibitors of GlcN/BSA/gold labeling on the tissue sections. The sugar specificity range detected by the glucosamine-binding sites included glucosamine, N-acetylglucosamine, mannose and fucose, whereas N-acetylgalactosamine, galactose and glucose were not detectable. A series of endotoxic substances such as Salmonella minnesota Re595 lipid A complex with BSA and lipopolysaccharides (LPS) derived from Escherichia coli 055:B5 or S. minnesota Re595 also competed with GlcN/BSA/gold binding. This indicates that the lipid A backbone glucosamine or other carbohydrate portions of LPS is a part of the structure recognized by glucosamine-binding sites.

Animals↗

PubMed1995

In vivo effects of glucosamine on insulin secretion and insulin sensitivity in the rat: possible relevance to the maladaptive responses to chronic hyperglycaemia.

We tested the hypothesis that glucosamine, a putative activator of glucose toxicity in vitro through acceleration of the hexosamine pathway, may determine in vivo the two key features of glucose toxicity in diabetes, namely, peripheral insulin resistance and decreased insulin secretion. Two groups of awake rats were studied either with intraarterial administration of glucosamine (5 mumol.kg-1.min-1) or saline. Insulin secretion was determined after arginine, glucose (hyperglycaemic clamp), and arginine/glucose infusions, while insulin-mediated glucose metabolism was assessed by the euglycaemic hyperinsulinaemic clamp in combination with [3-3H]-glucose infusion. Glucosamine had no effects on arginine-induced insulin secretion both at euglycaemia and hyperglycaemia, but significantly (40-50%) impaired glucose-induced insulin secretion (both first and second phases). During euglycaemic hyperinsulinaemic clamp studies, glucosamine decreased glucose uptake by approximately 30%, affecting glycolysis (estimated from 3H2O rate of appearance) and muscle glycogen synthesis (calculated from accumulation of [3H]-glucosyl units in muscle glycogen) to a similar extent. Muscle glucose 6-phosphate concentration was markedly reduced in the glucosamine-infused rats, suggesting an impairment in glucose transport/phosphorylation. Therefore, an increase in hexosamine metabolism in vivo: 1) inhibits glucose-induced insulin secretion, and 2) reduces insulin stimulation of both glycolysis and glycogen synthesis, thereby mimicking in normal rats the major alterations due to glucose toxicity in diabetes.

Animals↗

PubMed1991

Kinetic analysis of experimental post-operative peritoneal healing: the incorporation of proline and glucosamine by exudative and tissue repair cells.

The purpose of this study was to experimentally investigate the cellular composition of post-surgical peritoneal fluid and peritoneal tissue and determine the patterns of 14C-proline and 14C-glucosamine incorporation by the peritoneal exudative cells and peritoneal tissue repair cells (PEC and PTRC). One group of rabbits underwent resection (2.0 cm) and reanastomosis of their ileum, and another group underwent peritoneal wall abrasion. Postoperatively (1-28 days), the PEC and PTRC were collected and incubated for 5 days with 0.5 mu Ci 14C-glucosamine or 14C-proline, and the specific activity thereafter determined by beta counting. On the 1st postoperative day, the total cell number (TCN) has increased (7.7 x 10(7) cells/rabbit) to 770 per cent of the control values primarily as a result of the PMN influx (89.9 per cent). On day 3, the TCN was 6.1 x 10(7), 58.5 per cent of which comprised macrophages, which had become the principle cell type by day 5. The incorporation of proline and glucosamine into the PEC increased significantly peaking on day 7 then decreasing to the control value by day 21. Proline incorporation into the PTRC increased significantly, reaching a peak value on day 5, which decreased by day 10. Glucosamine incorporation reached a peak value on day 7 then decreased by day 10. In conclusion, the increase in glucosamine and proline incorporation into the PTRC parallels the increase in PEC, comprised principally of macrophages. These findings suggest that analysis of the metabolic activities in peritoneal activated macrophages may provide a useful tool to dissect the central mediation of postsurgical peritoneal re-epithelialization.

Animals↗

PubMed2006

Glucosamine-induced increase in Akt phosphorylation corresponds to increased endoplasmic reticulum stress in astroglial cells.

Increased glucose flux through the hexosamine biosynthetic pathway (HBP) is known to affect the activity of a number of signal transduction pathways and lead to insulin resistance. Although widely studied in insulin responsive tissues, the effect of increased HBP activity on largely insulin unresponsive tissues, such as the brain, remains relatively unknown. Herein, we investigate the effects of increased HBP flux on Akt activation in a human astroglial cells line using glucosamine, a compound commonly used to mimic hyperglycemic conditions by increasing HBP flux. Cellular treatment with 8 mM glucosamine resulted in a 96.8% +/- 24.6 increase in Akt phosphorylation after 5 h of treatment that remained elevated throughout the 9-h time course. Glucosamine treatment also resulted in modest increases in global levels of the O-GlcNAc protein modification. Increasing O-GlcNAc levels using the O-GlcNAcase inhibitor streptozotocin (STZ) also increased Akt phosphorylation by 96.8% +/- 11.0 after only 3 h although for a shorter duration than glucosamine; however, the more potent O-GlcNAcase inhibitors O-(2-acetamido-2-deoxy-D-glucopyranosylidene)amino-N-phenylcarbamate (PUGNAc) and 1,2-dideoxy-2'-propyl-alpha-D-glucopyranoso-[2,1-d]-Delta2'-thiazoline (NAGBT) failed to mimic the increases in phospho-Akt indicating that the Akt phosphorylation is not a result of increased O-GlcNAc protein modification. Further analysis indicated that this increased phosphorylation was also not due to increased osmotic stress and was not attenuated by N-acetylcysteine eliminating the potential role of oxidative stress in the observed phospho-Akt increases. Glucosamine treatment, but not STZ treatment, did correlate with a large increase in the expression of the endoplasmic reticulum (ER) stress marker GRP 78. Altogether, these results indicate that increased HBP flux in human astroglial cells results in a rapid, short-term phosphorylation of Akt that is likely a result of increased ER stress. The mechanism by which STZ increases Akt phosphorylation, however, remains unknown.

Acetylcysteine↗

PubMed1986

Glucosamine is a normal component of liver glycogen.

There have been several reports of the incorporation of glucosamine into liver glycogen by an intraperitoneal injection of galactosamine, but it has not previously been considered that glucosamine is a normal component of liver glycogen. We now report that glucosamine occurs endogenously in rabbit- and pig-liver glycogens in the amount of about 1 nmol per 10 mg glycogen. Like the glucosamine incorporated by exogenous administration of galactosamine, the endogenous glucosamine takes the place of 1,4-linked alpha-glucose residues. It is found in both the outer and inner chains of the glycogen molecule.

Animals↗

PubMed1989

Modulation of proline and glucosamine incorporation into tissue repair cells by peritoneal macrophages.

The purpose of this study was to determine the patterns of [14C]proline and [14C]glucosamine incorporation by tissue repair cells (TRC) as modulated by postsurgical macrophages. Rabbits underwent a midline laparotomy followed by resection (2.0 cm) and reanastomosis of their ileum. Another group of rabbits underwent peritoneal wall abrasion with sterile gauze until punctate bleeding developed. Postoperative (1-28 days) exudate cells (PEC) were recovered from the peritoneal cavity after reanastomosis, and (TRC) were obtained directly from the injured peritoneal surface after abrasion. Since the postsurgical exudate was composed mainly of macrophages, we examined the effect of postsurgical macrophage-spent media on the incorporation of [14C]proline, [14C]glucosamine, and [3H]thymidine by TRC. After 7 days of culture, Postsurgical Day 7 TRC were incubated with spent media from postsurgical PEC (greater than 90% macrophages). When TRC were cultured with macrophage-spent media, the number of TRC increased significantly compared to that of fresh medium-treated controls. The incorporation of [3H]thymidine by TRC was also enhanced by macrophage-spent media. The incorporation of [14C]proline and [14C]glucosamine by TRC was also enhanced when incubated with macrophage-spent medium. However, when data were expressed on a per cell basis, incorporation of [14C]proline and [14C]glucosamine by TRC cultured with macrophage-spent media was the same or less than that by cells incubated with fresh medium. These data suggest that the increase in incorporation of glucosamine and proline into connective tissue protein by postsurgical repair cells may be directly modulated by macrophages recruited in response to surgical injury and that this increase is due to the fibroproliferative effect of postsurgical macrophages.

Animals↗

PubMed1985

Administration of D-glucosamine into the third cerebroventricle induced feeding accompanied by hyperglycemia in rats.

D-glucosamine, 2-amino-2-deoxy-D-glucose, is known to be an endogenous glucose analogue and to antagonize glucose uptake and metabolism. The present experiments were aimed to clarify effects of glucosamine and related chemical substances on ingestive behavior, as well as its direct effects on hypothalamic neurons. Infusion of 24 mumole glucosamine into the third cerebroventricle induced feeding within 30 min in 5 rats out of 7 tested, accompanied by increased ambulatory activity. No periprandial drinking was observed. Plasma glucose level increased, peaking at 30 min after the injection. Plasma insulin level tended to increase, but not significantly. Electrophoretic application of glucosamine activated glucose-sensitive neurons in the lateral hypothalamus and suppressed glucoreceptors in the ventromedial hypothalamus. These facts, together with other reported results, suggest that glucosamine can modulate physiological feeding and that carbon 2 of the glucose molecule is important in feeding modulation by glucose analogues.

Animals↗

PubMed1979

The effects of concanavalin A, cerulenin, hydroxyurea and tunicamycin on the incorporation of amino acids and glucosamine in Tetrahymena pyriformis.

1. Pulse labelling of conjugating Tetrahymena pyriformis with glycine and glucosamine gave results consistent with a requirement for de novo synthesis of a lipid-like component which is involved in the addition of sugar to cell glycoprotein. 2. Conjugation of complementary strains of Tetrahymena can be inhibited without gross morphologic and metabolic changes in the cells. The observed inhibition of conjugation is reversible. 3. Concanavalin A stopped conjugation and stimulated both glycine and glucosamine incorporation. 4. Tunicamycin inhibited conjugation but had little influence on total glucosamine incorporation. Amino acid incorporation was slightly enhanced. 5. Hydroxyurea blocked conjugation, inhibited the incorporation of glucosamine and seemed to induce a transient increase in glycine incorporation. 6. Cerulenin inhibited conjugation but had little effect on the incorporation of glycine and glucosamine into the cell.

Amino Acids↗

PubMed1993

Synthesis of [1-11C]D-glucosamine and evaluation of its in vivo distribution in rat with PET.

D-Glucosamine is a structural unit of many biologically interesting macromolecules. To investigate the feasibility of using labelled D-glucosamine as a tracer for anabolic processes, a two-step synthetic procedure for specifically labelling D-glucosamine in position 1 with carbon-11 was developed. [11C]Cyanide was reacted with an imine precursor, N-benzyl-D-arabinosylamine, to generate the [1-11]alpha-amino nitrile. Reduction to [1-11C]D-glucosamine was accomplished by catalytic hydrogenation using PdCl2 and the N-benzyl group was simultaneously removed. The total synthesis time from end-of-trapping of [11C]cyanide was 40-45 min and the decay-corrected radiochemical yield was 5-10% after HPLC isolation. The biodistribution of [1-11C]D-glucosamine in rat following i.v. bolus injection was investigated using positron emission tomography and showed that the availability of this substance for CNS anabolism is low with the primary limitation being the intact blood-brain barrier.

Animals↗

PubMed2006

Glucosamine sulfate suppresses the expressions of urokinase plasminogen activator and inhibitor and gelatinases during the early stage of osteoarthritis.

BACKGROUND: Glucosamine sulfate may have an ex vivo inhibitory effect on the plasminogen activator (PA)/plasmin system and gelatinases expression during the early development of osteoarthritis (OA). METHODS: We compared the levels of urokinase-type PA (u-PA), PA inhibitor-1 (PAI-1) and gelatinases (matrix metalloproteinase-2 and -9 [MMP-2 and -9]) in a series of chondral, meniscal, and synovial cultures of early OA after treatment with or without glucosamine sulfate. RESULTS: Gelatin zymography revealed that glucosamine sulfate could suppress MMP-2 secretion in chondral, meniscal and synovial cultures and also decrease MMP-9 production in synovial and meniscal cultures. ELISA data also showed the suppressive effects of glucosamine sulfate on u-PA and PAI-1 production in synovial cultures at 48 h. CONCLUSIONS: Our data suggest that one of the therapeutic effects of glucosamine sulfate is to down-regulate the expressions of u-PA, PAI-1, MMP-2 and MMP-9 that underlie the destruction of articular cartilage in the early stage of OA, and therefore to delay the joint failure.

Enzyme Inhibitors↗