Dynamic control of oligosaccharide modification in the mammary gland: linking recombinant human erythropoietin functional analysis of transgenic mouse milk-derived hEPO.
We analyzed two transgenic mouse lines that secrete rhEPO in their milk to assess the dynamic control of N-linked oligosaccharides. Since pharmaceutically available epoetin alpha and beta are produced in CHO cells, we compared transgenic mammary gland-derived rhEPO to its CHO cell-derived counterpart. The major glycosyltransferases that determine the N-oligosaccharides patterns of rhEPO include N-acetylglycosaminyltransferase (GnT) and alpha1,3/4 fucosyltransferase (Fuc-TIV), GnT-III, -V and Fuc-TIV expression in the mouse mammary gland is significantly higher than that in Chinese hamster ovary (CHO)-derived cells, where the protein is not detectable. The data suggest that N-linked sugar chain patterns of recombinant glycoproteins, produced by the mammary gland differ, since GnT-III alters the sugar pattern extensively. In our experiments, rhEPO produced by the transgenic mice contains more tetra-acidic oligosaccharide structures than epoetin alpha derived from CHO cells, a rhEPO that is widely used therapeutically. Accordingly, we examined milk-derived rhEPO activity, both in vitro and in vivo. The rhEPO protein purified from the milk of mammary glands upregulates the EPO receptor-mediated expression of the STAT5 gene in MCF-7 cells in a dose-dependent manner, similar to the effects of epoetin alpha. Furthermore, direct injection of rhEPO into the mouse tail vein leads to an increase in the levels of blood components, such as red blood cells and platelets. In light of these findings, we suggest that the mammary glands of transgenic animals provide a sufficient environment to generate rhEPO with post-translational modifications for biopharmaceutical use.
Department of Dairy Science, Division of Applied Life Science, College of Agriculture and Life Science, Gyeongsang National University, 660-701, Chinju, GyeongNam, Korea.
Deug-Nam
DN
Kwon
Hyuk
H
Song
Jong-Yi
JY
Park
So-Young
SY
Lee
Seong-Keon
SK
Cho
Sung-Jo
SJ
Kang
Joung Soon
JS
Jang
Han Geuk
HG
Seo
Jin-Hoi
JH
Kim
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D016466:CHO Cells; D006224:Cricetinae; D003412:Cricetulus; D015180:Electrophoresis, Gel, Two-Dimensional; D004921:Erythropoietin / Q000737:chemistry* / Q000235:genetics / Q000502:physiology*; D005260:Female; D016695:Glycosyltransferases / Q000096:biosynthesis / Q000235:genetics; D006801:Humans; D007774:Lactation; D008297:Male; D008321:Mammary Glands, Animal / Q000201:enzymology / Q000378:metabolism*; D051379:Mice; D008810:Mice, Inbred C57BL; D008811:Mice, Inbred DBA; D008822:Mice, Transgenic; D008892:Milk / Q000378:metabolism; D008969:Molecular Sequence Data; D009844:Oligosaccharides / Q000737:chemistry / Q000378:metabolism*; D012333:RNA, Messenger / Q000378:metabolism; D011994:Recombinant Proteins / Q000737:chemistry* / Q000235:genetics* / Q000378:metabolism
D009844:Oligosaccharides; D012333:RNA, Messenger; D011994:Recombinant Proteins; D004921:Erythropoietin; D016695:Glycosyltransferases