6 The Department of Molecular and Cellular Biology, Roswell Park Cancer Institute, Elm and Carlton Streets, Buffalo, NY 14263
7 Department of Molecular and Cellular Biophysics, Roswell Park Cancer Institute, Elm and Carlton Streets, Buffalo, NY 14263
Received on January 27, 2003; revised on March 5, 2003; accepted on March 5, 2003
![]() |
Abstract |
---|
![]() ![]() ![]() ![]() ![]() ![]() ![]() |
---|
Key words: gene expression / immune response / inflammation / sialyltransferase / ST6Gal
![]() |
Introduction |
---|
![]() ![]() ![]() ![]() ![]() ![]() ![]() |
---|
The sialyltransferase ST6Gal I is principally responsible for the synthesis of Sia 2,6 to Galß1,4GlcNAc (Sia6LacNAc) termini of glycans (Tsuji, 1996
). A recently identified additional sialyltransferase in humans, ST6Gal II, can also theoretically elaborate the Sia6LacNAc termini (Takashima et al., 2002
). However, expression of the mouse ST6Gal II is restricted principally to the brain, and, more importantly, no liver expression was observed (F. Piller, personal communication). Furthermore, animals unable to elaborate functional ST6Gal I are essentially devoid of Sia6LacNAc structures (Hennet et al., 1998
; Manzi et al., 2000
; Martin et al., 2002
). Thus ST6Gal I is the dominant Sia6LacNac-synthesizing enzyme in the mouse and the exclusive source of these structures in liver (Manzi et al., 2000
; Martin et al., 2002
).
In contrast to ST6Gal II, ST6Gal I and Sia6LacNAc structures have widespread tissue distribution in mammals, but their levels of expression vary, with liver, lactating mammary gland, intestinal epithelia of newborn pups, and activated B cells generally being sources of highest expression (Dalziel et al., 2001). Tissue differences in ST6Gal I expression are attributed largely to differential usage of a number of physically distinct promoters controlling the single ST6Gal I gene Siat1 in mouse (Wuensch et al., 2000
), and this feature is evolutionarily retained in the rat (Svensson et al., 1990
; Wang et al., 1990
), human (Wang et al., 1993
), and bovine (Mercier et al., 1999
) ST6Gal I genes. In liver, two distinct promoter-regulatory regions, P1 and P3, are operative. P1, whose utilization in adult animals is apparently restricted to liver (Hu et al., 1997
), is the major contributor to the hepatic ST6Gal I mRNA pool and is operative in the ST6Gal I up-regulation during acute phase response (APR) (Dalziel et al., 1999
). P3, on the other hand, is constitutively utilized in an apparently tissue-nonspecific manner (Svensson et al., 1990
). P3 mediates the synthesis of the remainder but significant proportion of hepatic ST6Gal I mRNA. In contrast, development- and stage-specific ST6Gal I expression in B lineage cells is mediated by a different set of physically distinct promoter-regulatory regions, P2a, P2b, P2c, in addition to P3 (Wuensch et al., 2000
). ST6Gal I expression in lactating mammary gland is mediated by P4 (Dalziel et al., 2001
).
The intricate nature of ST6Gal I regulation suggests a model for multifaceted contribution of ST6Gal I and Sia6LacNAc that is curiously not supported by the ST6Gal I-deficient mouse, which is reportedly normal except for B cellrelated immunodeficiency (Hennet et al., 1998). Gagneux and Varki (1999)
advanced a general explanation that glycan diversity is shaped by exogenous pressures, such as viral and microbial pathogens, and mutant animals, such as the ST6Gal I-null mice, generally thrive symptom-free because of the absence of these exogenous pressures in the specific-pathogen-free environment of vivariums.
The hepatic inflammatory response, or APR, is a cumulative homeostatic process executed in response to tissue injury, trauma, infection, or tumor burden (Baumann and Gauldie, 1994). APR prevents ongoing tissue damage, isolates the inflammation to site of injury, and returns the body to stasis. Hepatic ST6Gal I, like other acute phase plasma proteins, is elevated during APR (Kaplan et al., 1984
; Lammers and Jamieson, 1986
; Dalziel et al., 1999
) by cytokine- and glucocorticoid-mediated activation of the P1-associated transcriptional start site (Baumann et al., 1993
; Dalziel et al., 1999
). It is commonly thought that elevation of hepatic ST6Gal I is necessary to modify the burst of acute phase plasma proteins, many of which are heavily sialylated. ST6Gal enzymatic activity in serum is also elevated during APR, the source of which is believed to be the liver (Kaplan et al., 1984
; Lammers and Jamieson, 1986
; Weinstein et al., 1987
).
Here, we partially inactivate Siat1, the mouse ST6Gal I gene, by disruption of the liver-specific P1 transcriptional start site to generate the mutant, Siat1P1. We show that the B cell response is not disrupted in Siat1
P1 mice, in contrast to the systemically ablated ST6Gal I-null animals. We test the consequence of P1 disruption on the hepatic APR and on the response to challenge with Salmonella typhimurium, an intracellular bacillus that elicits a well-described repertoire of host responses, including multiple phases of innate, cellular, and humoral immunity (Tagliabue et al., 1985
; Nencioni et al., 1987
; Acharya et al., 1987
; Murphy et al., 1989
; Forrest et al., 1991
).
![]() |
Results |
---|
![]() ![]() ![]() ![]() ![]() ![]() ![]() |
---|
|
|
Hepatic acute phase response of Siat1P1 animals
The APR was elicited by subcutaneous injection of the sterile irritant turpentine. Hepatic ST6Gal I mRNA response to the inflammatory signal, elevated four- to fivefold in WT animals, was lost in P1-disrupted mice (Figure 3A). However, ablation of the P1 region in Siat1 did not abolish the overall hepatic APR response. There was normal elevation of the well-known APR plasma proteins1-acid glycoprotein, haptoglobin, and serum amyloid Aon the hepatic mRNA level (Figure 3B, 3C, and 3D, respectively). Accumulation of APR plasma proteins in the serum following the inflammatory stimulus was indistinguishable between WT control and Siat1
P1 animals (data not shown and Figure 4A). The hepatic mRNA level of ST3Gal-III, an
2,3-sialyltransferase that also acts on the Galß1,4GlcNAc termini as ST6Gal, was unchanged in Siat1
P1 animals both in the absence or in the presence of inflammatory signal (Figure 3E). Two-dimensional gel analysis following turpentine injection showed no difference in isoelectric distribution of plasma proteins, which is consistent with unaltered degree of Sia modification (Figure 4A). SNA lectin blot analysis of plasma glycoproteins during APR also revealed no difference in degree of
2,6-linked Sia modification (Figure 4B).
|
|
|
Humoral response of Siat1P1 animals
In contrast to those in the ST6Gal I-null animal (Hennet et al., 1998), resting B cells isolated from the Siat1
P1 mouse showed no discernible difference with WT mouse in terms of surface IgM or SNA reactivity (not shown). To evaluate the humoral immune response capabilities of the Siat1
P1 mouse, we challenged the animals with the hapten NP [(4-hydroxy-3-nitrophenyl)acetyl] complexed to chicken
-globulin that generates a well-characterized B cell response (Jacob et al., 1991
; Jacob and Kelsoe, 1992
; Takahashi et al., 1998
) measurable by enzyme-linked immunosorbent assay (ELISA) or by the expression of the
Ig light chain that is rarely used in the C57BL/6 mouse and allows visualization of the B cells arising specifically in response to the NP challenge (Jacob et al., 1991
; Jacob and Kelsoe, 1992
).
On challenge with NP, Siat1P1 mice were identical to C57BL/6 WT mice in the kinetics and magnitude of production of anti-NP antibodies of the IgM, IgG1, and IgG3 isotypes as measured by ELISA over a course of 40 days (Figure 6AC, respectively). Moreover, the development of NP-specific (using
chain Ig light chain as marker) and peanut agglutininreactive germinal centers in the spleen were identical between the Siat1
P1 and WT animals on challenge with NP (not shown).
|
|
|
|
|
![]() |
Discussion |
---|
![]() ![]() ![]() ![]() ![]() ![]() ![]() |
---|
It has often been remarked, albeit without clear substantiation, that liver is the source of the soluble serum ST6Gal activity whereby the catalytic domain of the normally membrane-bound enzyme is proteolytically released and secreted (Kaplan et al., 1983; Weinstein et al., 1987
; Richardson and Jamieson, 1995
). The Siat1
P1 animal provides the first definitive evidence that liver is the major source of serum ST6Gal enzyme. P1 and its unique transcription initiation site is the predominant promoter-regulatory region governing ST6Gal I expression in liver, and disruption of P1 resulted in serum ST6Gal enzymatic activity that was 2.5-fold lower than WT levels (see Figure 5).
WT mice undergoing APR exhibited elevated serum ST6Gal activity by three- to fourfold. Quite unexpectedly, a three- to fourfold increase was also observed in Siat1P1 mice following APR induction by turpentine. This observation is consistent with the idea that at least two independent mechanisms are responsible for the elevated serum ST6Gal activity during APR. Between the two mechanisms, increased hepatic transcription of Siat1 mediated by P1 and enhanced proteolytic release of existing enzyme, only the former is abrogated by P1 mutagenesis.
The constitutive P3 remains functional in Siat1P1 animals and likely contributes significantly to the residual serum ST6Gal activity. Alternatively, although liver is the dominant source of serum ST6Gal activity under normal physiologic conditions, it is quite possible that other tissues contribute to the elevation of ST6Gal during APR. Indeed it has been demonstrated that rat small intestine ST6Gal activity is elevated in response to the APR (Hutton et al., 1987
; Ch et al., 1988
). Serum ST6Gal activity may also be derived from a newly identified second
2,6-sialyltransferase, ST6Gal II, encoded on a gene distinct from Siat1 (mouse chromosomes 17 and 16, respectively, as detailed in the mouse genome database, Wellcome Trust Sanger Institute, Ensembl ID ENSMUG00000024172 and Ensembl ID ENSMUG00000022885, respectively). However, ST6Gal II is both highly tissue-specific (brain) and weakly expressed (F. Piller, personal communication).
Elevation of hepatic ST6Gal activity during APR has often been viewed as a simple response to the increased need for sialylation of APR plasma proteins, many of which are heavily 2,6-sialylated. However, APR plasma protein isoelectric profiles of Siat1
P1 animals are indistinguishable from WT animals, suggesting a normal extent of sialic acid substitution. Siat1
P1 serum APR proteins also exhibit normal SNA binding, which reflects the degree of
2,6-sialyl substitution. Although these rudimentary approaches cannot visualize subtle alterations in glycan structures, these observations nevertheless indicate that P1 is unnecessary for adequate sialylation of plasma proteins during APR. The minimal level of hepatic ST6Gal I mRNA maintained in the absence of functional P1 is apparently sufficient for sialylation of APR plasma proteins.
If ST6Gal I induction is not needed to address the demand to sialylate serum APR proteins, what then is the physiologic value of P1-mediated Siat1 transcription? Gagneux and Varki (1999) suggested that the endogenous function(s) of ST6Gal I may be restricted to B cells and that ST6Gal I expression at other locations serves to interfere with invading pathogens, many of which bind preferentially to
2,3-sialyl structures (Karlsson, 1995
).
The significance of soluble ST6Gal activity in systemic circulation and its elevation as part of the inflammatory response remain unclear, although it is unlikely that the enzyme would function in the circulation due to the lack of CMP-Sia (Kaplan et al., 1983). In keeping with the view that APR functions to limit the inflammatory response to the site of injury, there is the possibility that ST6Gal is delivered through the circulation and used at distal sites (the site of injury, for instance).
S. typhimurium infection elicits a well-described repertoire of host responses, including all phases of innate, cellular, and humoral immunity, that is an ideal readout to assess the impact of glycosylation in multiple phases of the host immune response. We have demonstrated that the humoral compartment, which is important for the eventual resolution of the infection, is intact in Siat1P1 animals, unlike the systemic ST6Gal I-null animal (Hennet et al., 1998
). Thus any altered immune response in Siat1
P1 animals toward S. typhimurium is unlikely to be mediated through defects in the B cell compartment.
The most pronounced observed consequence of P1 disruption is a greater than twofold elevated infiltration of leukocytes into the peritoneal space within 18 h of IP challenge with S. typhimurium (see Figure 8). The major component of this infiltrate is granulocytes because 86% of the total peritoneal leukocytes are Gr-1+ in the Siat1P1 animals, with the remainder consisting of macrophages (Mac-1+/Gr-1), NK (NK1.1+), T (TCRß+), and B (B220+) cells (data not shown). This is followed by generally greater spleno-/hepatomegaly and by greater leukocyte infiltration into spleen and liver by 3 and 6 days after S. typhimurium inoculation. Together, these observations suggest altered leukocyte trafficking patterns as a consequence of P1 disruption, although the mechanistic basis of ST6Gal I contribution to leukocyte functionality outside the B cell compartment remains to be elucidated. One additional observed phenotype is the generally greater bacterial burden suffered in the liver and spleen of the Siat1
P1 animals (see Figure 7). The greater bacterial burden appears counterintuitive because it is more reasonable to predict that elevated leukocyte trafficking would be counterproductive to bacterial invasion and expansion.
Further work is necessary to determine whether or not the altered leukocyte infiltration is limited to the granulocyte subset and to define the mechanistic rationale of this phenotype. In addition to granulocytes themselves, the phenotype may be present in vascular endothelial cells, or some other cell type involved in leukocyte trafficking to the peritoneum. Presently, it is not clear how altered expression of Siat1 in the liver can contribute to altered granulocytic migration into the peritoneal cavity in response to bacterial challenge.
The Galß1,4GlcNAc-R structure utilized by ST6Gal I is also a precursor for the elaboration of a number of structures such as polylactosamines and sialyl-Lewis x with physiologic relevance to leukocyte migration and targeting. Changes in ST6Gal I activity can theoretically alter the pool of Galß1,4GlcNAc structures available for the synthesis of these other structures. However, the bulk of the Lewis and polylactosamine structures occur on the GlcNAcß6-Man6-Man branch of the N-glycan tetra-antennary chain that is not preferred by the ST6Gal I (Joziasse et al., 1987
). Moreover
2,6-sialylation of Galß1,4GlcNAc-R structures on O-linked glycans are rarely reported.
In keeping with a model for multifaceted contribution of ST6Gal I, and given the widespread tissue distribution of this sialyltransferase, it is also possible that multiple sites are impacted by abrogation of P1, leading to the diverse and apparently counterintuitive phenotypes. Finally, although P1 has long been recognized as a hepatic-specific regulator of Siat1 transcription, this belief is based principally on RNA surveys of complete organs. There is the possibility that the P1 is utilized in some nonhepatic cell type(s) or in a developmentally specific manner that is not amenable to detection by gross tissue RNA surveys. P1 ablation may lead to disruption of Siat1 expression in a nonhepatic cell subset that may ultimately impact different phases of the host repertoire against pathogenic challenge.
![]() |
Materials and methods |
---|
![]() ![]() ![]() ![]() ![]() ![]() ![]() |
---|
APR assays
Routinely, the APR was induced by subcutaneous injection of turpentine (100 µl) into the hind-leg region of Siat1P1 or WT 129/Svjae. Serum was collected by tail bleeding at 2 weeks before and 48 h after turpentine (or saline) injection. Animals were sacrificed 48 h postturpentine treatment, and livers were collected and snap-frozen in liquid N2.
For western blot analysis, serum aliquots (25 µl) were separated on 10% sodium dodecyl sulfatepolyacrylamide gel electrophoresis (SDSPAGE) and subjected to SNA analysis. Blots were blocked in 5% nonfat dry milk and 0.1% Tween 20 for at least 1 h at room temperature or overnight at 4°C. For detection of 2,6-linked sialic acids, the blots were probed with biotinylated-SNA (5 µg/ml, Vector Laboratories, Burlingame, CA) and then incubated with streptavidinhorseradish peroxidase (1:2000 dilution) and visualized with enhanced chemiluminescence reagent (Amersham, Little Chalfont, UK). Two dimensional gel analysis was performed using Mini-Protean II 2-D gel system (BioRad, Hercules, CA). Typically 1 µl of serum was used. The isoelectric focusing dimension contained 1.6% BioLyte 5/7, 0.4% BioLyte 3/10, and 0.8% BioLyte 3/5 ampholytes.
Sialyltransferase assays
Sialyltransferase assays were carried out under incubation conditions as described (Chandrasekaran et al., 1995). For measurement of sialyltransferase activity, 10 µl of serum from Siat1
P1 or WT 129/Svjae were incubated with CMP-3[H]NeuNAc and monitored for the transfer of 3[H] NeuNAc to the exogenously supplied acceptor compound, Galß4GlcNA
-o-Bn. NeuNAc transferred from CMP-3[H]NeuNAc was measured after recovery and separation of acceptor and 3[H]-sialylated acceptor compounds from unreacted CMP-3[H]NeuNAc and free 3[H]NeuNAc by C18-reverse phase chromatography (Ujita et al., 1998
). 3[H] NeuNAc-labeled acceptor was quantified by scintillation counting. To avoid misleading results due to substrate depletion, the amount of CMP-3[H] NeuNAc conversion was kept below 5% at the termination of the reactions.
Measurement of B cell response
Antigen preparation and immunization were performed as described by Jacob et al. (1991). NP-chicken gamma globulin (NP22-CGG, Biosearch Technologies, Novato, CA) was precipitated in alum (NP-CG/alum). Groups of C57BL/6 and Siat1
P1 mice were immunized with a single IP injection (50 mg in a volume of 200
L) NP-CG/alum. Control groups (day 0) were injected with 200 µL saline. For this experiment, 23-month-old male and female C57BL/6 mice and Siat1
P1 animals, back-crossed 10 successive generations to C57BL/6 background, were used.
ELISA assays of serum IgM, IgG1, and IgG3 were performed as follows. MaxiSorp Nunc-Immuno plates were coated with 50 µg/ml of NP bovine serum albumin (NP23-BSA, from Biosearch Technologies) in 0.1 M carbonate buffer, pH 9.0, at 4°C overnight and blocked with 0.5% BSA in carbonate buffer (Takahashi et al., 1998). Sera collected at indicated times and diluted to various concentrations were plated on NP23-BSA-coated plates at room temperature for 2 h. After washing with phosphate buffered saline (PBS) containing 0.1% Tween 20, sera was analyzed using anti-mouse isotype-specific antibodies, IgM, IgG1, or IgG3, conjugated to alkaline phosphatase (SBA Clonotyping System/AP from Southern Biotechnology Associates, Birmingham, AL). Alkaline phosphatase activity was visualized using SigmaFast p-nitrophenyl phosphate (Sigma, St. Louis, MO), and optical density values were obtained using a microplate reader.
S. typhimurium infections
A doubly attenuated strain of S. typhimurium, BRD509, which contains mutations in the aroA and aroD genes (Hoiseth and Stocker, 1981; Strugnell et al., 1992
) was used. Siat1
P1, back-crossed 10 successive generations to C57BL/6 background, and age/sex-matched WT C57BL/6 cohorts (typically 1012-week-old females) were infected with varying doses (ranging from 400,000 to 12,500,000 CFU) by IP injection. Typically three to five animals of the Siat1
P1 strain and a similar number of WT control animals were used for each experimental point.
Overnight cultures of S. typhimurium BRD509 were washed in PBS, and IP was injected into mice without the use of anesthesia. The number of S. typhimurium in an inoculum was estimated by absorbance at 600 nm. Actual infective S. typhimurium doses were verified by culturing an aliquot of the inoculum overnight on MacConkey agar plates.
At time points indicated, the animals were sacrificed by CO2 asphyxiation. Peritoneal exudate cells were harvested in ice-cold RPMI 1640 (Gibco, Grand Island, NY). Livers and spleens were dounce homogenized and passed through a 100-µm filter, and erythrocytes were hypotonically lysed. Liver homogenates were further processed by differential centrifugation through a Lympholyte M cushion (Accurate Chemical, Westbury, NY) to remove hepatocytes. Viable leukocytes from liver, spleen, and peritoneum were enumerated with a hemocytometer by Trypan blue exclusion. Immunofluorescent staining and flow cytometric analysis of leukocyte subsets were performed as follows. Cells (0.51 x 106) were washed in PBS containing 0.5% BSA and 0.02% sodium azide (PAB). Fc receptor sites were blocked by incubation with goat serum (1:10, Gibco) and anti-CD16/32 (Fc III/II Receptor) Fc Block (Pharmingen, San Diego, CA). Samples were then incubated with combinations of fluorescently labeled antibodies recognizing B cells (B220), T cells (TCRß), NK cells (NK1.1), neutrophils (Gr-1), and CD11b (Mac-1); washed with PAB; and fixed in 1% formaldehyde. Flow cytometric analysis was performed using a FACScan flow cytometer (Becton-Dickinson Immunocytometry Systems, Franklin Lakes, NJ) and the CellQuest software package. The total bacterial burden, including both extracellular S. typhimurium and bacteria located within host cells, was determined by lysing serially diluted eukaryotic cells in sterile water. The bacteria were then cultured overnight on MacConkey agar plates, and the resultant colonies were counted. Statistical analysis of bacterial burden and leukocyte numbers and populations was performed using unpaired t-test with a significance cutoff of p = 0.05.
![]() |
Acknowledgements |
---|
![]() |
Footnotes |
---|
2 Present address: Dept of Cell Biology, Second Military Medical University, 800 Xiang Yin Road, Shanghai 200433, China.
3 Present address: Division of Nutritional Sciences, Cornell University, 108 Savage Hall, Ithaca, NY 14853.
4 Present address: Davis H. Smith Center for Vaccine Biology and Immunology, University of Rochester, Rochester, NY 14642.
5 To whom correspondence should be addressed; e-mail: joseph.lau{at}roswellpark.org
![]() |
Abbreviations |
---|
![]() |
References |
---|
![]() ![]() ![]() ![]() ![]() ![]() ![]() |
---|
Baumann, H. and Gauldie, J. (1994) The acute phase response. Immunol. Today, 15, 7480.[CrossRef][ISI][Medline]
Baumann, H., Morella, K.K., and Campos, S.P. (1993) Interleukin-6 signal communication to the alpha-1-acid glycoprotein gene, but not junB gene, is impaired in HTC cells. J. Biol. Chem., 268, 1049510500.
Ch, S.W., Carter, E.A., Tompkins, R.G., and Burke, J.F. (1988) Increase of sialyltransferase activity in the small intestine following thermal injury in rats. Biochem. Biophys. Res. Commun., 153, 377381.[ISI][Medline]
Chandrasekaran, E.V., Jain, R.K., Larsen, R.D., Wlasichuk, K., and Matta, K.L. (1995) Selectin ligands and tumor-associated carbohydrate structures: specificities of alpha 2,3-sialyltransferases in the assembly of 3'-sialyl-6-sialyl/sulfo Lewis a and x, 3'-sialyl-6'-sulfo Lewis x, and 3'-sialyl-6-sialyl/sulfo blood group T-hapten. Biochemistry, 34, 29252936.[ISI][Medline]
Dalziel, M., Lemaire, S., Ewing, J., Kobayashi, L., and Lau, J.T.Y. (1999) Hepatic acute phase induction of murine beta-galactoside alpha2,6 sialyltransferase (ST6Gal-1) is IL-6 dependent and mediated by elevation of Exon H-containing class of transcripts. Glycobiology, 9, 10031008.
Dalziel, M., Huang, R.-A., Dall'Olio, F., Morris, J.R., Taylor-Papadimitriou, J., and Lau, J.T.Y. (2001) Mouse ST6Gal sialyltransferase gene expression during mammary gland lactation. Glycobiology, 11, 407412.
Forrest, B.D., LaBrooy, J.T., Beyer, L., Dearlove, C.E., and Shearman, D.J. (1991) The human humoral immune response to Salmonella typhi Ty21a. J. Infect. Dis., 163, 336345.[ISI][Medline]
Gagneux, P. and Varki, A. (1999) Evolutionary considerations in relating oligosaccharide diversity to biological function. Glycobiology, 9, 747755.
Hennet, T., Chui, D., Paulson, J.C., and Marth, J.D. (1998). Immune regulation by the ST6Gal sialyltransferase. Proc. Natl Acad. Sci. USA, 95, 45044509.
Hestdal, K., Ruscetti, F.W., Ihle, J.N., Jacobsen, S.E., Dubois, C.M., Kopp, W.C., Longo, D.L., and Keller, J.R. (1991) Characterization and regulation of RB6-8C5 antigen expression on murine bone marrow cells. J. Immunol., 147, 2228.
Hoiseth, S.K. and Stocker, B.A. (1981) Aromatic-dependent Salmonella typhimurium are non-virulent and effective as live vaccines. Nature, 291, 238239.[ISI][Medline]
Hu, Y.P., Dalziel, M., and Lau, J.T.Y. (1997) Murine hepatic beta-galactoside alpha 2,6-sialyltransferase gene expression involves usage of a novel upstream exon region. Glycoconj. J., 14, 407411.[CrossRef][ISI][Medline]
Hutton, C.W., Corfield, A.P., Clamp, J.R., and Dieppe, P.A. (1987) The gut in the acute phase response: changes in colonic and hepatic enzyme activity in response to dermal inflammation in the rat. Clin. Sci., 73, 165169.[ISI][Medline]
Jacob, J. and Kelsoe, G. (1992) In situ studies of the primary immune response to (4-hydroxy-3-nitrophenyl)acetyl. II. A common clonal origin for periarteriolar lymphoid sheath-associated foci and germinal centers. J. Exp. Med., 176, 679687.[Abstract]
Jacob, J., Kassir, R., and Kelsoe, G. (1991) In situ studies of the primary immune response to (4-hydroxy-3-nitrophenyl)acetyl I. The architecture and dynamics of responding cell populations. J. Exp. Med., 173, 11651175.[Abstract]
Joziasse, D.H., Schiphorst, W.E., Van den Eijnden, D.H., Van Kuik, J.A., Van, Halbeek, H., and Vliegenthart, J.F. (1987) Branch specificity of bovine colostrum CMP-sialic acid: Gal beta 14GlcNAc-R alpha 26-sialyltransferase. Sialylation of bi-, tri-, and tetraantennary oligosaccharides and glycopeptides of the N-acetyllactosamine type. J. Biol. Chem., 262, 20252033.
Kaplan, H.A., Woloski, B.M.R.N.J., Hellman, M., and Jamieson, J.C. (1983) Studies on the effect of inflammation on rat liver and serum sialyltransferase: evidence that inflammation causes release of Gal ß1-4 GlcNAc 2-6 sialyltransferase from liver. J. Biol. Chem., 258, 1150511509.
Kaplan, H.A., Woloski, B.M., and Jamieson, J.C. (1984) Studies of the effect of experimental inflammation on rat liver nucleotide sugar pools. Comp. Biochem. Physiol., 77, 207212.[CrossRef]
Karlsson, K.A. (1995) Microbial recognition of target-cell glycoconjugates. Curr. Opin. Struct. Biol., 5, 622635.[CrossRef][ISI][Medline]
Kelm, S., Schauer, R., and Crocker, P.R. (1996) The sialoadhesinsa family of sialic acid-dependent cellular recognition molecules within the immunoglobulin superfamily. Glycoconj. J., 13, 913926.[ISI][Medline]
Lammers, G. and Jamieson, J.C. (1986) Studies on the effect of experimental inflammation on sialyltransferase in the mouse and guinea pig. Comp. Biochem. Physiol. B., 84, 181187.[ISI][Medline]
Manzi, A.E., Norgard-Sumnicht, K., Argade, S., Marth, J.D., van Halbeek, H., and Varki, A. (2000) Exploring the glycan repertoire of genetically modified mice by isolation and profiling of the major glycan classes and nano-NMR analysis of glycan mixtures. Glycobiology, 10, 669689.
Martin, L.T., Marth, J.D., Varki, A., and Varki, N.M. (2002) Genetically altered mice with different sialyltransferase deficiencies show tissue-specific alterations in sialylation and sialic acid 9-O-acetylation. J. Biol. Chem., 277, 3293032938.
Mercier, D., Wierinckx, A., Oulmouden, A., Gallet, P.F., Palcic, M.M., Harduin-Lepers, A., Delannoy, P., Petit, J.-M., Leveziel, H., and Julien, R. (1999) Molecular cloning, expression and exon/intron organization of the bovine ß-galactoside 2,6-sialyltransferase. Glycobiology, 9, 851863.
Murphy, J.R., Wasserman, S.S., Baqar, S., Schlesinger, L., Ferreccio, C., Lindberg, A.A., and Levine, M.M. (1989) Immunity to Salmonella typhi: considerations relevant to measurement of cellular immunity in typhoid-endemic regions. Clin. Exp. Immunol., 75, 228233.[ISI][Medline]
Nelson, R.M., Venot, A., Bevilacqua, M.P., Linhardt, R.J., and Stamenkovic, I. (1995) Carbohydrate-protein interactions in vascular biology. Annu. Rev. Cell Dev. Biol., 11, 601631.[CrossRef][ISI][Medline]
Nencioni, L., Villa, L., De Magistris, M.T., Romano, M., Boraschi, D., and Tagliabue, A. (1987) Cellular immunity against Salmonella typhi after live oral vaccine. Adv. Exp. Med. Biol., 216B, 16691675.
Pousset, D., Piller, V., Bureaud, N., Monsigny, M., and Piller, F. (1997) Increased alpha2,6 sialylation of N-glycans in a transgenic mouse model of hepatocellular carcinoma. Cancer Res., 57, 42494256.[Abstract]
Richardson, K. and Jamieson, J.C. (1995) Release of sialyltransferases from rat liver Golgi membranes by a cathepsin D-like proteinase: comparison of the release of Gal beta 1-4GlcNAc alpha 2-6 sialyltransferase, Gal beta 1-3(4)GlcNAc alpha 2-3 sialyltransferase and lactosylceramide alpha 2-3 sialyltransferase (SAT-1). Comp. Biochem. Physiol. B., 110, 445450.[CrossRef][ISI][Medline]
Strugnell, R., Dougan, G., Chatfield, S., Charles, I., Fairweather, N., Tite, J., Li, J.L., Beesley, J., and Roberts, M. (1992) Characterization of a Salmonella typhimurium aro vaccine strain expressing the P.69 antigen of Bordetella pertussis. Infect. Immun., 60, 39944002.[Abstract]
Svensson, E.C., Soreghan, B., and Paulson, J.C. (1990) Organization of the ß-galactoside 2,6-sialyltransferase gene: evidence for the transcriptional regulation of terminal glycosylation. J. Biol. Chem., 265, 2086320868.
Tagliabue, A., Nencioni, L., Caffarena, A., Villa, L., Boraschi, D., Cazzola, G., and Cavalieri, S. (1985) Cellular immunity against Salmonella typhi after live oral vaccine. Clin. Exp. Immunol., 62, 242247.[ISI][Medline]
Takahashi, Y., Dutta, P.R., Cerasoli, D.M., and Kelsoe, G. (1998) In situ studies of the primary immune response to (4-hydroxy-3-nitrophenyl)acetyl. V: Affinity maturation develops in two stages of clonal selection. J. Exp. Med., 187, 885895.
Takashima, S., Tsuji, S., and Tsujimoto, M. (2002) Characterization of the second type of human beta-galactoside alpha 2,6-sialyltransferase (ST6Gal II), which sialylates Galbeta 1, 4GlcNAc structures on oligosaccharides preferentially. Genomic analysis of human sialyltransferase genes. J. Biol. Chem., 277, 4571945728.
Tsuji, S. (1996) Molecular cloning and functional analysis of sialyltransferases. J. Biochem. Tokyo, 120, 113.[Abstract]
Ujita, M., McAuliffe, J., Schwientek, T., Almeida, R., Hindsgaul, O., Clausen, H., and Fukuda, M. (1998) Synthesis of poly-N-acetyllactosamine in core 2 branched O-glycans. The requirement of novel beta-1,4-galactosyltransferase IV and beta-1,3-n-acetylglucosaminyltransferase. J. Biol. Chem., 273, 3484334849.
Varki,A. (1993) Biological roles of oligosaccharides. Glycobiology, 3, 97130.[Abstract]
Varki,A. (1997) Sialic acids as ligands in recognition phenomena. FASEB J., 11, 248255.
Wang, X.C., O'Hanlon, T.P., Young, R.F., and Lau, J.T.Y. (1990) Rat beta-galactoside alpha 2,6-sialyltransferase genomic organization: alternate promoters direct the synthesis of liver and kidney transcripts. Glycobiology, 1, 2531.[Abstract]
Wang, X.C., Vertino, A., Eddy, R.L., Byers, M.G., Jani-Sait, S.N., Shows, T.B., and Lau, J.T.Y. (1993) Chromosome mapping and organization of the human beta-galactoside alpha 2,6-sialyltransferase gene. Differential and cell-type specific usage of upstream exon sequences in B-lymphoblastoid cells. J. Biol. Chem., 268, 43554361.
Weinstein, J., Lee, E.U., McEntee, K., Lai, P.H., and Paulson, J.C. (1987) Primary structure of ß-galactoside 2,6-sialyltransferase. Conversion of membrane-bound enzyme to soluble forms by cleavage of the NH2-terminal signal anchor. J. Biol. Chem., 262, 1773517743.
Wuensch, S.A., Huang, R.-A., Ewing, J., Liang, X.L., and Lau, J.T.Y. (2000) Murine B cell differentiation is accompanied by programmed expression of multiple novel ß-galactoside 2,6-sialyltransferase mRNA forms. Glycobiology, 10, 6775.