These findings demonstrate the stress-protective role of PrP(C) during development, and propose PrP(C) dysregulation as a novel causative element of IUGR.

Objectives: Measuring protein markers with variable glycosylation, such as thyroid-stimulating hormone (TSH), with high accuracy is not an easy task. Despite highly sensitive third-generation tests, discrepancies among TSH assays still remain unsolved and are the focus of important standardization efforts. Earlier work from our group showed that a lack of similarity in epitope expression between standards and samples may account for discordant hormone measurements. In this study, we aimed at producing a glycoengineered TSH with serum-type glycosylation and compared its immunological behavior to that of the international standards. Study Design: Recombinant glycoengineered TSH (rgTSH) was produced in glycoengineered Chinese hamster ovary cells to express a highly sialylated TSH and tested in newly designed assays. Two groups of assays targeting defined epitopes were constructed and TSH levels were estimated in a panel of 84 clinical samples (2.1-22.4 mIU/l) based on the use of the current 3rd IS 81/565, the 1st IRP 94/674 and rgTSH calibrations. Results: Calibration based on rgTSH was found to significantly reduce the percentage difference means of assays compared to the pituitary standard. We also found that a switch from a mIU/l (3rd IS 81/565) to ng/l (rgTSH) basis can be established within the normal as well as in the mid to upper normal range of TSH levels. Of interest, TSH assays targeting the main immunogenic region displayed variable TSH values, indicating that, in this region, epitopes should be defined for assays to deliver similar values. Conclusions: A glycoengineered TSH with serum-type glycosylation proved to be a new calibrator efficient in harmonizing TSH values.

When recombinant glycoproteins for therapeutic use are to be produced on an industrial scale, there is a crucial need for technologies that can engineer fast-growing stable cells secreting the protein drug at a high rate and with a defined and safe glycosylation profile. Current cell lines approved for drug production are essentially from rodent origin. Their glycosylation machinery often adds undesired carbohydrate determinants which may alter protein folding, induce immunogenicity, and reduce circulatory life span of the drug. Notably, sialic acid as N-acetylneuraminic acid is not efficiently added in most mammalian cells and the 6-linkage is missing in rodent cells. Engineering cells with the various enzymatic activities required for sialic acid transfer has not yet succeeded in providing a human-like pattern of glycoforms to protein drugs. To date, there is a need for engineering animal cells and get highly sialylated products that resemble as closely as possible to human proteins. We have designed ST6Gal minigenes to optimize the ST6GalI sialyltransferase activity and used them to engineer ST6(+)CHO cells. When stably transfected in cells expressing a protein of interest or not, these constructs have proven to equip cell clones with efficient transfer activity of 6-linked sialic acid. In this chapter, we describe a methodology for generating healthy stable adherent clones with hypersialylation activity and high secretion rate.