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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Cytotechnology 14 (1994), S. 39-45 
    ISSN: 1573-0778
    Keywords: beta actin ; CHO ; FSH ; metallothionein ; promoter type
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract The expression levels of recombinant human follicle stimulating hormone (r-hFSH) were studied in several CHO-K1 derived cell lines. The cell lines varied in the promoter used to control r-hFSH expression and in the subunit gene copy ratio. FSH is a heterodimeric molecule, with 2 N-glycosylation sites per peptide chain, and shares a common alpha subunit with the other gonadotropins. Serum stimulated FSH production in the beta actin promoter cell lines 2–3 times over the 7–10 ng/106 cells/h levels obtained in protein-free medium. Serum seemed to have roles other than purely at the transcriptional level judging by the increased free alpha to dimer ratio secreted from cell cultrured in serum-free medium. Zinc induced FSH expression in metallothionein cell lines, with a 3-fold induction at 50μM concentrations compared to 0μM zinc, giving specific productivities of about 7–10 ng/106 cells/h, but the induction kinetics were complicated, and suggested other roles for zinc in addition to activation of the metallothionein promoter. Evidence suggested significant post-transcriptional regulation of FSH expression.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Cytotechnology 17 (1995), S. 13-19 
    ISSN: 1573-0778
    Keywords: Butyrate ; FSH ; glycosylation ; precursor supplementation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract A Chinese Hamster Ovary (CHO-K1) derived cell line, which expresses human follicle stimulating hormone (hFSH) under the control of a beta actin promoter, was used as a model system to study heterologous glycoprotein expression. It has been shown previously that specific productivities in this cell line were three times higher in the presence of serum than in its absence. In this paper, a systematic study was made of the affects of various serum components of product levels in order to determine if the affect of serum on FSH expression could be duplicated by defined medium supplements. Culture media were supplemented with growth factors, direct activators of secondary messengers, steroids, lipids and various sugars. It was shown that the components with the most stimulatory affect of hFSH expression were sodium butyrate, mevalonate and hydrocortisone. Although butyrate has been shown to elevate transcription of some genes, it was concluded that this could not have been the only mechanism of action, since mevalonate and hydrocortisone are both implicated in the lipid pathway of protein glycosylation, but not with transcriptional activation of the beta actin promoter. Conversely, actual supply of dolichol-linked oligosaccharide for glycosylation was probably not rate limiting, since butyrate has never been reported to affect the supply of this comerabolite, but glycosylation is likely to be implicated in some way
    Type of Medium: Electronic Resource
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