Deglycosylation of a bifunctional lutropin-follitropin agonist reduced its follitropin activity more than its lutropin activity.
OBJECTIVE
To design a drug that blocks the gonadal actions of lutropins and follitropins.


METHODS
Controlled in vitro study.


METHODS
Academic laboratory.


METHODS
None.


METHODS
We removed three glycosylation signals from an hCG-hFSH chimera known to have high affinity for LH and FSH receptors, expecting this would create a bifunctional antagonist (dgCFC). To offset the inhibition of subunit combination caused by deglycosylation of alpha-subunit loop 2, we prepared dgCFC as a single-chain fusion protein containing the alpha-subunit downstream of the chimeric beta-subunit.


METHODS
Receptor binding, cyclic adenosine monophosphate accumulation.


RESULTS
dgCFC bound LH or FSH receptors similar to hCG or hFSH. It was a partial agonist and had one tenth the efficacy of hFSH and two thirds the efficacy of hCG.


CONCLUSIONS
The surprising high residual lutropin activity of dgCFC indicated that its FSH residues offset the effects of deglycosylation, suggesting this approach to preparing a bifunctional antagonist is unlikely to lead to a useful drug. The increased lutropin efficacy of dgCFC relative to deglycosylated hCG supports the idea that oligosaccharides modulate glycoprotein hormone efficacy through an influence on hormone conformation.
Trout
S W
SW
Department of Obstetrics and Gynecology, Robert Wood Johnson (Rutgers) Medical School, Piscataway, New Jersey, USA.
Han
Y
Y
Myers
R V
RV
Bernard
M P
MP
Moyle
W R
WR
D000595:Amino Acid Sequence; D000818:Animals; D004353:Drug Evaluation, Preclinical; D005640:Follicle Stimulating Hormone / Q000502:physiology*; D006031:Glycosylation; D006801:Humans; D007986:Luteinizing Hormone / Q000502:physiology*; D008969:Molecular Sequence Data; D051381:Rats; D011962:Receptors, FSH / Q000819:agonists*; D011974:Receptors, LH / Q000819:agonists*
D011962:Receptors, FSH; D011974:Receptors, LH; D007986:Luteinizing Hormone; D005640:Follicle Stimulating Hormone