Modification of the goat mammary gland glycosylation pathway | 72043
International Research Journals

International Research Journal of Biochemistry and Bioinformatics

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Modification of the goat mammary gland glycosylation pathway by overexpression of GnT-IVa


Maria Jose Leiva Carrasco*

Statement of the Problem: Recombinant glycoprotein expression has been carried out in different expression systems based on the genetic modification. Specifically, recombinant glycoproteins whose biological activity depends on post-translational modifications are produced in cell tissue culture, which increases the manufacturing cost. The production of biotherapeutics in the mammary glands of genetically modified mammals results in an alternative method to overcome the drawback of cell culture expression system. However, the N-glycosylation pattern of complex glycoproteins produced in the mammary epithelia has showed diminished antennae formation and lower sialic acid contents compare to native protein. An alternative to obtain high- quality biopharmaceuticals in milk could be the modification of the N-glycosylation pattern by overexpression of exogenous glycosyltransferases. The purpose of this study is to modify in vivo the glycosylation pattern of recombinant protein expressed in goat mammary gland. Methodology & Theoretical Orientation: Human erythropoietin fused to human IgG Fc (EPO-Fc) was coexpressed with N-acetyl-glucosaminyltransferase-IVa (GnT-IVa) by adenoviral transduction in goat mammary gland. Findings: The modification in vivo of the enzymatic glycosylation machinery in the mammary gland generated an increment in the antennae number. A higher population of tri-antennary structures for the EPOFc/GnT-IV variant was obtained by N-glycans mass spectrometry analysis, compared to bi-antennary structures N- linked to EPO-Fc expressed in the same cells. Conclusion & Significance: These results demonstrate, for the first time, that it is possible to modify in vivo the glycosylation pattern of recombinant biopharmaceutical expressed in the goat mammary gland epithelial cells to obtain a glycosylation pattern similar to native glycoproteins.

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