Context:
Previous studies suggest that aging in women is associated with a reduction in hypoglycosylated forms of FSH.
Objective:
Experiments were performed to determine whether glycosylation of the FSHß subunit modulates the biological activity of FSH in human granulosa cells.
Design and Setting:
Recombinant human FSH (hFSH) derived from GH3 pituitary cells was purified into fractions containing hypoglycosylated hFSH21/18 and fully glycosylated hFSH24. The response to FSH glycoforms was evaluated using the well-characterized, FSH-responsive human granulosa cell line, KGN at an academic medical center.
Interventions:
Granulosa cells were treated with increasing concentrations of fully- or hypoglycosylated FSH glycoforms for periods up to 48 hours.
Main Outcome Measure(s):
The main outcomes were indices of cAMP-dependent cell signaling and estrogen and progesterone synthesis.
Results:
We observed that hypoglycosylated FSH21/18 was significantly more effective than fully glycosylated FSH24 at stimulating cAMP accumulation, protein kinase A (PKA) activity, and cAMP response element binding protein (CREB) (S133) phosphorylation. FSH21/18 was also much more effective than hFSH24 on the stimulation CREB-response element–mediated transcription, expression of aromatase and STAR proteins, and synthesis of estrogen and progesterone. Adenoviral-mediated expression of the endogenous inhibitor of PKA, inhibited FSH21/18- and FSH24-stimulated CREB phosphorylation, and steroidogenesis.
Conclusions:
Hypoglycosylated FSH21/18 has greater bioactivity than fully glycosylated hFSH24, suggesting that age-dependent decreases in hypoglycosylated hFSH contribute to reduced ovarian responsiveness. Hypoglycosylated FSH may be useful in follicle stimulation protocols for older patients using assisted reproduction technologies.

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