TY - JOUR
T1 - The sialylated oligosaccharides of recombinant bovine lutropin modulate hormone bioactivity
AU - Smith, P. L.
AU - Kaetzel, D.
AU - Nilson, J.
AU - Baenziger, J. U.
PY - 1990/1/15
Y1 - 1990/1/15
N2 - The Asn-linked oligosaccharides from bovine lutropin (bLH(Pit)) are predominantly dibranched complex-type structures with the terminal sequence SO4-4GalNAcβ1,4GlcNAcβ1,2Manα. Recombinant bLH expressed in Chinese hamster ovary cells (bLH(CHO)) bears di- (60%) and tribranched (30%) complex-type oligosaccharides; however, these terminate in the sequence Siaα2,3Galβ1,4GlcNAcβ1,2Manα. In contrast to the limited spectrum of oligosaccharide structures present on recombinant bLH(CHO), the endogenous glycoproteins synthesized by CHO cells bear a heterogeneous array of Asn-linked oligosaccharides with 0, 1, 2, 3, or 4 sialic acid moieties. The sialic acid moieties on the Asn-linked oligosaccharides of both endogenous glycoproteins and recombinant bLH(CHO) are exclusively α2,3-linked, suggesting that the α2,6-sialyl-transferase is not active in CHO cells. The bioactivities of bLH(Pit) and bLH(CHO) were compared using MA-10 cells following sequential digestion with neuraminidase and β-galactosidase. Neither the ED50 (dose producing 50% of the maximum response) for progester-one production (7.2 ng/ml) nor the Pmax (maximum level of progesterone produced) (470 ng/ml) was altered for bLH(Pit) by these treatments, consistent with the absence of either sialic acid or Gal on bLH(Pit). The ED50 for progesterone production by recombinant bLH(CHO) (16.4 ng/ml) was significantly greater than for bLH(Pit) but was reduced to 5.3 ng/ml following removal of terminal sialic acid. Removal of the subterminal Gal was without further effect. The Pmax for bLH(CHO) (180 ng/ml) was not altered by these treatments. The reduction in bLH(CHO) bioactivity caused by the presence of terminal sialic acid suggests that the presence of terminal sulfate on bLH(Pit) oligosaccharides may also reduce its bioactivity and may play a modulatory role in regulating hormone bioactivity.
AB - The Asn-linked oligosaccharides from bovine lutropin (bLH(Pit)) are predominantly dibranched complex-type structures with the terminal sequence SO4-4GalNAcβ1,4GlcNAcβ1,2Manα. Recombinant bLH expressed in Chinese hamster ovary cells (bLH(CHO)) bears di- (60%) and tribranched (30%) complex-type oligosaccharides; however, these terminate in the sequence Siaα2,3Galβ1,4GlcNAcβ1,2Manα. In contrast to the limited spectrum of oligosaccharide structures present on recombinant bLH(CHO), the endogenous glycoproteins synthesized by CHO cells bear a heterogeneous array of Asn-linked oligosaccharides with 0, 1, 2, 3, or 4 sialic acid moieties. The sialic acid moieties on the Asn-linked oligosaccharides of both endogenous glycoproteins and recombinant bLH(CHO) are exclusively α2,3-linked, suggesting that the α2,6-sialyl-transferase is not active in CHO cells. The bioactivities of bLH(Pit) and bLH(CHO) were compared using MA-10 cells following sequential digestion with neuraminidase and β-galactosidase. Neither the ED50 (dose producing 50% of the maximum response) for progester-one production (7.2 ng/ml) nor the Pmax (maximum level of progesterone produced) (470 ng/ml) was altered for bLH(Pit) by these treatments, consistent with the absence of either sialic acid or Gal on bLH(Pit). The ED50 for progesterone production by recombinant bLH(CHO) (16.4 ng/ml) was significantly greater than for bLH(Pit) but was reduced to 5.3 ng/ml following removal of terminal sialic acid. Removal of the subterminal Gal was without further effect. The Pmax for bLH(CHO) (180 ng/ml) was not altered by these treatments. The reduction in bLH(CHO) bioactivity caused by the presence of terminal sialic acid suggests that the presence of terminal sulfate on bLH(Pit) oligosaccharides may also reduce its bioactivity and may play a modulatory role in regulating hormone bioactivity.
UR - http://www.scopus.com/inward/record.url?scp=0025176933&partnerID=8YFLogxK
M3 - Article
C2 - 2295623
AN - SCOPUS:0025176933
SN - 0021-9258
VL - 265
SP - 874
EP - 881
JO - Journal of Biological Chemistry
JF - Journal of Biological Chemistry
IS - 2
ER -