The Trapping of Uridine Phosphates by d‐Galactosamine, d‐Glucosamine, and 2‐Deoxy‐d‐galactose

Abstract

The effects of D-galactosamine, D-glucosamine, and 2-deoxy-~-galactose on rat liver uracil nucleotides were studied in vivo. Enzymic and isotope dilution analyses of the UDP-sugars and of uridine phosphates revealed three major, related changes : an accumulation of the respective UDP-sugar derivatives, a marked decrease of UTP, UDP, and UMP, and a subsequent increase of the sum of hepatic uracil nucleotides. The decrease of uridine phosphates was accompanied by diminished contents of UDPG and UDP-galactose. UMP of total liver RNA was not altered significantly. Inhibition of uridylate synthesis by use of 6-azauridine resulted in a suppression of the D-galactosamine-induced stimulation of uridine phosphate synthesis and of the increase in total acid soluble uracil nncleotides. The trapping of uridine phosphates by formation of UDP-sugar derivatives was most pronounced and most prolonged after administration of D-galactosamine. The uridine phosphate content was lowered to less than loo/, of normal within three hours, while the sum of uracil nucleotides increased by 0.35 pmole xg liver-1 xhour-l, from an initial value of 1.24 p.mole/g. The quantitative analysis of the time dependent changes of UDP-hexosamines, UDP-N-acetylhexosamines, UDPG, and UDP-galactose revealed a pronounced alteration by D-galactosamine of the UDP-sugar pattern.Corresponding changes in the distribution of liver uracil nucleotides were obtained after administration of D-glucosamine and 2-deoxy-~-galactose. Both, however, are ineffective in provoking hepatitis. I n contrast to D-galactosamine, D-ghCOSamine and S-deoxy-~-galactose do not lead to the formation of UDP-hexosamines; furthermore they are less efficient in trapping uridine phosphates in vivo. These observations contribute to an understanding of the orotatemediated prevention of the galactosamine-induced liver damage, and of the role of pyrimidine nucleotides in this experimental hepatitis. phates with a subsequent decrease Of their levels i71.nucleoside monophosphokinase, or ATP : nucleosidemono-

NFκB and Caspase-3 Activity in Apoptotic Hepatocytes of Galactosamine-sensitized Mice Treated with TNFα

“…It should be noted that NFB could not be found in the nuclei of non-apoptotic hepatocytes 4.5 hr after GalN/TNF␣ treatment. GalN depleted hepatic uridine nucleotides and formed uridine diphosphate hexosamine complexes (Keppler et al 1970). Two hours after GalN injection the decrease of the intracellular uridine triphosphate concentration leads to a reduction in liver protein synthesis of about 40%.…”

“…Neither injection of 700 mg/kg GalN nor of 5 g/kg TNF␣ induced hepatocellular apoptosis 4.5 hr after administration (Figures 9B and 9C). Administration of GalN produced uridine diphosphate hexosamine complexes (Keppler et al 1970), which could be seen as various amounts of dark-red precipitates in the individual hepatocytes of HE-stained LR Whitesemithin sections (Figures 9C and 9D). In the apoptotic hepatocytes large amounts of these complexes were found.…”

Nucleoside‐Diphosphate Derivatives of 2‐Deoxy‐d‐glucose in Animal Cells

“…Therefore it is unlikely that 2-deoxy-~-glucose is epimerized to any significant extent to 2-deoxy-~-galactose at the U DP level. In two communications [38,39] Keppler and coworkers found a depletion of the UTP-pool in liver by administration of 2-deoxy-~-galactose. The increase of UDP in the acid extracts was taken as indirect evidence that both UDP-2-deoxy-~-galactose and UDP-2-deoxy-~-glucose were formed as acid labile intermediates.…”

A bacteriocidal effect of 2-deoxy-D-galactose on Escherichia coli due to inhibition of amino sugar metabolism.

“…While, FBPase activity was inhibited to almost 14% of the original level in the presence of 1.2 mM dGa1P in the assay with the enzyme from ara-207. The enzyme from the deal-resistant strain (IFO 3992) was also sensitive to dGal1P, being mostly 2-Deoxyhexose analogs have been of biological interest such as the inhibitory effect on the cell wall glucan and glycoprotein synthesis in yeast cells (13)(14)(15) as well as the induction of liver injury in animal cells (11,12). In animal cells, deal is metabolized through the Leloir pathway upto uridine 5'-diphosphate 2-deoxy-Dglucose (UDPdGIc) and finally gave a pool of uridine 5'-diphosphate 2-deoxy-Dgalactose (UDPdGa1) and UDPdGlc.…”

“…In animal cells, deal is metabolized through the Leloir pathway upto uridine 5'-diphosphate 2-deoxy-Dglucose (UDPdGIc) and finally gave a pool of uridine 5'-diphosphate 2-deoxy-Dgalactose (UDPdGa1) and UDPdGlc. Hepatotoxicity of deal is therefore elucidated by depletion of the pool of uridine phosphate which can interfere with UTPdependent biosynthesis of macromolecules (12). On the other hand, deal 1 P is considered to be the ultimate metabolite of deal in E. coli cells, thereby accounting for its role as an effector in dGal-induced stasis (1).…”