Inositol phosphate stimulation by LH requires the entire α Asn56 oligosaccharide

Van T. Nguyen, Vinod Singh, Vladimir Y. Butnev, Ciann M. Gray, Suzanne Westfall, John S Davis, James A. Dias, George R. Bousfield

Research output: Contribution to journalArticle

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Abstract

Lentil lectin-bound, fucose-enriched hTSH was reported to stimulate both cAMP and inositol phosphate (IP) intracellular signalling pathways, whereas fucose-depleted hTSH stimulated only the cAMP pathway. Gonadotropins activate the cAMP pathway and in several studies higher concentrations activate the IP pathway. Since only the 10% of α subunit Asn56 oligosaccharides (Asn52 in humans) are fucosylated, the higher glycoprotein hormone concentrations required for IP pathway activation might be related to the abundance of competent hormone isoforms. Lentil lectin-fractionated equine (e)LHα and eFSHα preparations were combined with a truncated, des(121-149)eLHβ preparation. All four hybrid hormone preparations induced IP accumulation in porcine theca cells, suggesting that activation of the IP pathway was not dependent on fucosylation at α subunit Asn56. However, the presence of Asn56 carbohydrate was necessary for increased IP accumulation. Intact, rather than Asn56-deglycosylated eLH preparations provoked a biphasic steroidogenic response by rat testis Leydig cells, suggesting that Gαi stimulation was also sensitive to loss of Asn56 carbohydrate. While rat granulosa cells responded to human FSH preparations in a biphasic manner, a classical sigmoidal response was obtained to eFSH and Asn56-deglycosylated eFSH, suggesting that the equine preparations did not activate Gαi. Purified oLHα Asn56 oligosaccharides inhibited FSH-stimulated steroidogenesis in rat granulosa cell cultures indicating a direct role for carbohydrate in FSH action. The same carbohydrate preparation inhibited hCG-stimulated fluorescence energy transfer suggesting oligosaccharide involvement in activated LH receptor self-association.

Original languageEnglish (US)
Pages (from-to)73-86
Number of pages14
JournalMolecular and Cellular Endocrinology
Volume199
Issue number1-2
DOIs
StatePublished - Jan 31 2003

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Inositol Phosphates
Oligosaccharides
Carbohydrates
Rats
Fucose
Granulosa Cells
Hormones
Horses
Chemical activation
Human Follicle Stimulating Hormone
Theca Cells
LH Receptors
Leydig Cells
Energy Transfer
Gonadotropins
Cell culture
Energy transfer
Testis
Glycoproteins
Protein Isoforms

Keywords

  • Carbohydrate
  • Deglycosylation
  • Gonadotropin
  • Inositol phosphate
  • Steroidogenesis

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Endocrinology

Cite this

Nguyen, V. T., Singh, V., Butnev, V. Y., Gray, C. M., Westfall, S., Davis, J. S., ... Bousfield, G. R. (2003). Inositol phosphate stimulation by LH requires the entire α Asn56 oligosaccharide. Molecular and Cellular Endocrinology, 199(1-2), 73-86. https://doi.org/10.1016/S0303-7207(02)00297-6

Inositol phosphate stimulation by LH requires the entire α Asn56 oligosaccharide. / Nguyen, Van T.; Singh, Vinod; Butnev, Vladimir Y.; Gray, Ciann M.; Westfall, Suzanne; Davis, John S; Dias, James A.; Bousfield, George R.

In: Molecular and Cellular Endocrinology, Vol. 199, No. 1-2, 31.01.2003, p. 73-86.

Research output: Contribution to journalArticle

Nguyen, VT, Singh, V, Butnev, VY, Gray, CM, Westfall, S, Davis, JS, Dias, JA & Bousfield, GR 2003, 'Inositol phosphate stimulation by LH requires the entire α Asn56 oligosaccharide', Molecular and Cellular Endocrinology, vol. 199, no. 1-2, pp. 73-86. https://doi.org/10.1016/S0303-7207(02)00297-6
Nguyen, Van T. ; Singh, Vinod ; Butnev, Vladimir Y. ; Gray, Ciann M. ; Westfall, Suzanne ; Davis, John S ; Dias, James A. ; Bousfield, George R. / Inositol phosphate stimulation by LH requires the entire α Asn56 oligosaccharide. In: Molecular and Cellular Endocrinology. 2003 ; Vol. 199, No. 1-2. pp. 73-86.
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