• 대한의생명과학회지
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• 제15권2호
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• pp.161-166
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• 2009

Human erythropoietin(EPO) is a glycoprotein that enhances red blood cell production by stimulating proliferation and differentiation of erythroid progenitor cells in the bone marrow. Patients with chronic kidney disease(CKD) suffer from anemia caused by reduced production of EPO in the kidney. Recombinant human EPO protein has been used successfully for the treatment of anemia associated with CKD. Recently, attention has been paid to the development of side effect of EPO, pure red cell aplasia(PRCA), in some patients with CKD. PRCA is a rare disorder of erythropoiesis that leads to a severe anemia due to an almost complete cessation of red blood cell production. EPO-related PRCA is caused by the production of EPO-neutralizing antibodies(Abs) that eliminate the biological activity of EPO as well as endogenous EPO in patients undergoing therapy. Since 1988, almost 200 cases worldwide have been reported with Ab-positive PRCA after receiving EPO therapeutics. The underlying mechanisms of the breaking of immune tolerance to self-EPO have been investigated. Modification of formulation, organic compounds of container closures, and route of administration has been suggested for the possible mechanism of increased immunogenicity of EPO. A number of assays have been used to detect Abs specific to EPO. These assays are generally grouped into two major categories: binding Ab assays and neutralizing Ab assays(bioassays). There are several types of binding Ab assays, including radioimmunoprecipitation assay, enzyme-linked immunosorbent assay, and the BIAcore biosensor assay. In vitro cell-based bioassays have been utilized for the detection of neutralizing Abs. Finally, the recent experience with anti-EPO Abs may have considerable implications for the future development and approval of EPO preparations. Also, considering that millions of patients are being treated with EPO, clinicians need to be aware of signs and consequences of this rare but severe clinical case.

• Biomolecules & Therapeutics
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• 제6권1호
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• pp.56-62
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• 1998

Mutagenicity of recombinant human erythropoietin (rhEPO) was examined in the reverse mutation test on bacteria, in the chromosomal aberration test on cultured mammalian cells and in the micronucleus test on mice. The reverse mutation test was performed by a plate incorporation method with or wothout a metabolic activation system (59 Mix) using Salmonella typhimurium strain TA100, TA1535, TA98 and TA 1537. The rhEPO did not significantly increase revertant colonies in any of the test strains under any conditions at dose levels ranging from 1000 H/ml to 62.5 lu/plate, compared with the vehicle control. In the chromosomal aberration test using cultured Chinese Hamster Lung (CHL) cells, the number of aberrant cells was not increased in the presence or absence of 59 Mix at concentrations of 1000 lU/ml to 250 lU/ml, compared with the vehicle control. In the micronucleus test, male ICR mice were given rhEPO intraperitoneally at a dose level of 25000, 12500 and 6250 lU/kg. The incidence of bone marrow micronucleated polychromatic erythrocytes was not different from that of the vehicle control. From these results, rhEPO is considered to be non-mutagenic under the present test conditions.

• Reproductive and Developmental Biology
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• 제34권3호
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• pp.193-199
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• 2010

We report here the production of transgenic chickens that can regulate human erythropoietin (hEPO) gene expression. The glycoprotein hormone hEPO is an essential for viability and growth of the erythrocytic progenitors. Retrovirus vector system used in this study has two features including tetracycline-controllable promoter and woodchuck hepatitis virus posttranscriptional regulator element (WPRE). The former is for to reduce the possibility of physiological disturbance due to constitutional and unregulated expression of hEPO gene in the transgenic chicken. The latter is for maximum expression of the foreign gene when we turn-on the gene expression. A replication-defective Moloney murine leukemia virus (MoMLV)-based vectors packaged with vesicular stomatitis virus G glycoprotein (VSV-G) was injected beneath the blastoderm of non-incubated chicken embryos (stage X). Out of 325 injected eggs, 28 chicks hatched after 21 days of incubation and 16 hatched chicks were found to express the hEPO gene delivered by the vector. The biological activity of the recombinant hEPO in transgenic chicken serum was comparable to its commercially available counterpart. The recombinant hEPO in transgenic chicken serum had N- and O-linked carbohydrate simillar to that produced from in vitro cultured cells transformed with hEPO gene.

• Biomolecules & Therapeutics
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• 제6권3호
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• pp.312-316
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• 1998

Efficacy and in vivo bioassay of recombinant human erythropoietin (rho-EPO), was investigated. Efficacy studies were conducted in normal, and cisplatin-induced anemic rats. Normal and anemic animals were treated intravenously with rhu-EPO for 5 days, and the changes in the number of red blood cells (RBC), hemoglobin concentration (Hb), hematocrit value (Hct) and percentage reticulocyte value (Ret, reticulocyte/RBC) were examined. In normal rats, rho-EPO significantly increased RBC, Hb, Hct and Ret at the doses of 50∼ 1,250 lU/kg/day in a dose-dependent fashion. Cisplatin-induced anemic rats showed significant increase of RBC, Hb, Hct and Ret after administration of rho-EPO (50-200 lU/kg/day) in a dose-dependent manner. These changes of hematological parameters disappeared gradually after cessation of the treatment. The in vivo bioassay results in polycythemic mice showed that rho-EPO had 90% of bioactivity compared to NIBSC standard rhu-EPO. These results suggest that rho-EPO might be useful for the therapy of anemia originated from renal failure and chemotherapy-induced anemia.

• 한국동물번식학회:학술대회논문집
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• 한국동물번식학회 2003년도 학술발표대회 발표논문초록집
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• pp.17-17
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• 2003

The milk of transgenic animals may provide an attractive vehicle for large-scale production of hEPO. Since glycosylation is cell type specific, recombinant human EPO (rhEPO) produced in different host cells contain different patterns of oligosaccharides, which could affect the biological functions. However, there have been no reports on the characteristics of rhEPO derived from milk of transgenic animals. To address this objective, several transgenic mice by using pWAPhEPO and/or pBC1hEPO expression vector were produced. However, 2 lines of pWAPhEPO founder female mouse died during late gestational day (day 18) before offspring could be obtained. They showed a severe splenomegaly, Unlike those of pWAPhEPO, mammary gland epithelial cells from biopsies of lactating pBC1hEPO transgenic mice had marked immunoreactivity to EPO and any activity was not detected in other tissues. The expression level of rhEPO is about 0.7% of mammary gland cellular total soluble proteins and an amount of 300~500 mg/L rhEPO is secreted into milk. Furthermore, the pBC1hEPO transgenic mice transmitted this character to their progeny in mendelian manner. In order to determine the extent of glycosylation variation, N-linked oligosaccharide structures present in the milk-derived rhEPO were characterized. Most of milk-derived rhEPO is fully glycosylated. the biological activity of milk-derived rhEPO was comparable to that of purified CHO-derived rhEPO, and milk-derived rhEPO showed relatively stable after freezing and thawing. Taken together, the results illustrate the potential of transgenic animals in the large-scale production of biopharmaceuticals.

• 약학회지
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• 제47권6호
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• pp.422-431
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• 2003

The use of recombinant human erythropoietin (rhEPO), a stimulator of erythropoiesis, banned in sports because of the medical risk associated with thrombosis. Due to analytical difficulties to differentiate between natural human EPO (hEPO) and rhEPO, blood parameters of erythropoiesis such as contents of hemoglobin (cut-off value <17.5 g/d l for man, and < 16.0 g/dl for women), hematocrit and reticulocytes (cut-off value <2.0%) were measured to focus the misuse of rhEPO. We conducted anti-doping test for 122 blood samples of the World Cup athletes. The mean values of key parameters are as follows; 14.5$\pm$1.0 g/dl for hemoglobin, 41.7$\pm$2.8% for hematocrit, and 1.3$\pm$0.4% for reticulocyte. Blood sample was found to be stable up to 8 hours for the reticulocyte measurement. In addition, the soluble transferrin receptor and ferritin levels were measured by immunoassay methods using plasma samples (n=28) in which the mean value was 0.8$\pm$0.5 $\mu\textrm{g}$/$m\ell$ and 54.6$\pm$33.7 ng/$m\ell$, respectively. The results indicate that all samples tested were negative for the blood parameters of indirect anti-doping test for hEPO misuse. The statistical evaluation suggest that several other parameters such as red blood cell, mean corpuscular hemoglobin concentration, mean corpuscular volume, mean corpuscular hemoglobin and white blood cell could be considered as factors influencing hEPO function in addition to five parameters mentioned.

• 식물조직배양학회지
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• 제24권1호
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• pp.63-69
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• 1997

Erythropoietin(EPO)은 적혈구 모세포의 분화와 성장을 중재하는 당단백질이며 담배 식물체에서 재조합 사람 EPO를 생산하기 위해 CaMV 35S promoter를 갖는 발현 vector인 pBI$\Delta$GUS121, pBD$\Delta$ GUS121, pPEV-1을 이용하여 5.4kb의 EPO genomic DNA를 cloning 하였고 Agrobacterium tumefaciens에 의한 형질전환에 의해 Nicotiana tabacum (var. Xanthi)으로 도입되었다. Kanamycin을 포함하는 MS 배지에서 각각의 construct에 대하여 10 km 저항성 식물체들이 얻어졌다. 형질전환된 식물체의 게놈에 EPO genomic DNA의 정확한 결합은 polymerase chain reaction에 의해 332bP의 DNA 조각에 의해 확인되었으며 Northern blot 결과 1.8 kb의 전사체들이 식물체 잎에서 발현 축적되는 것이 확인되었다. Promoter의 수나 5'-UTS 서열에 의한 mRNA 양에는 변화가 없었지만 식물체 게놈에 결합된 위치 및 copy number에 의해 mRNA 수준에 영향을 주는 것으로 밝혀졌다. EPO 항체를 이용한 Western blot 결과 식물체에서 발현된 EPO 단백질의 크기는 동물세포에서 발현된 37kDa 보다 작은 30 kDa 이었다. 이는 식물체에서 modification(glycosylation) system은 동물세포에서와는 다르다는 것을 보여준다.

• 한국미생물·생명공학회지
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• 제32권2호
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• pp.142-148
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• 2004

에리스로포이에틴은 인간 적혈구분화의 조절인자로 작용한다. 유전자 재조합 인간에리스로포이에틴(rhEPO)은 동물세포에서 생산되고 있는 재조합 당단백질의 하나이며 당쇄부분이 전체 분자량의 40％를 차지한다. 시알산 함량은 체내약물 투여 지속기간과 직접적인 연관이 있어 시알산 함량은 의약용 당단백질의 중요한 성질로 여겨진다. 본 연구에서는 CHO세포 배양액에 시알산 생합성 전구물질인 N-acetylmannosamine(ManNAc)과 sialidase 저해제인 2-deoxy-2,3-hyo-N-acetylneuraminic acid(NeuAc2en)를 첨가하여 rhEPO의 sialic acid함량을 증가시킬 수 있었다. 특히, 배양액에 20 mM ManNAc/0.5 mM NeuAc2en를 첨가할 때 대조구에 비하여 약 10배의 시알산 함량이 증가하였으며 세포성장이나 배양액의 rhEPO생산량에는 영향이 없었다. rhEPO의 정제시 시알산 함량이 11∼15％인 다당쇄 rhEPO분획을 얻었으며, 배양액 내에 20 mM ManNAc와 0.5 mM NeuAc2en를 동시에 첨가함으로 대조구에 비하여 시말산함량이 높은다당쇄 rhEPO의 생산성이 50％ 증가하였다.

• Journal of Microbiology and Biotechnology
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• 제18권2호
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• pp.383-391
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• 2008

The glycans linked to the insect cell-derived glycoproteins are known to differ from those expressed in mammalian cells, partly because of the low level or lack of glycosyltransferase activities. GnT II, GnT IV, GnT V, and ST3Gal IV, which play important roles in the synthesis of tetraantennarytype complex glycan structures in mammalian cells, were overexpressed in Trichoplusia ni cells by using a baculovirus expression vector. The glycosyltransferases, expressed as a fusion form with the IgG-binding domain, were secreted into the culture media and purified using IgG sepharose resin. The enzyme assay, performed using a pyridylaminated-sugar chain as an acceptor, indicated that the purified glycosyltransferases retained their enzyme activities. Human erythropoietin expressed in T. ni cells (rhEPO) was subjected to in vitro glycosylation by using recombinant glycosyltransferases and was converted into complex-type glycan with terminal sialic acid. The presence of Nacetylglucosamine, galactose, and sialic acid on the rhEPO moiety was detected by a lectin blot analysis, and the addition of galactose and sialic acid to rhEPO was confirmed by autoradiography using $UDP-^{14}C-Gal\;and\;CMP-^{14}C-Sia$ as donors. The in vitro glycosylated rhEPO was injected into mice, and the number of reticulocytes among the ed blood cells was counted using FACS. A significant increase in the number of reticulocytes was not observed in the mice injected with in vitro glycosylated rhEPO as compared with those injected with rhEPO.

• Molecules and Cells
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• 제37권11호
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• pp.819-826
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• 2014

Protein modifications of recombinant pharmaceuticals have been observed both in vitro and in vivo. These modifications may result in lower efficacy, as well as bioavailability changes and antigenicity among the protein pharmaceuticals. Therefore, the contents of modification should be monitored for the quality and efficacy of protein pharmaceuticals. The interface of EPO and its receptor was visualized, and potential amino acids interacting on the interface were also listed. Two different types of modifications on the interface were identified in the preparation of rHu-EPO BRP. A UPLC/Q-TOF MS method was used to evaluate the modification at those variants. The modification of the oxidized variant was localized on the Met54 and the deamidated variants were localized on the Asn47 and Asn147. The extent of oxidation at Met54 was 3.0% and those of deamidation at Asn47 and Asn147 were 2.9% and 4.8%, respectively.