Endocrinology, Vol 119, 561-565, Copyright © 1986 by Endocrine Society
Gonadotropin-releasing hormone stimulates the synthesis of the polypeptide chains of luteinizing hormone
A Starzec, R Counis and M Jutisz
The effect of GnRH on the synthesis of the polypeptide chains of LH was
reevaluated using the incorporation of labeled methionine by pituitary
cells in culture, followed by specific immunoprecipitation of LH- related
subunits and sodium dodecyl sulfate-polyacrylamide gel analysis of
immuno-precipitated peptides. Fluorography and counting of labeled subunits
separated on the gels demonstrated that the presence of GnRH in the medium
significantly enhanced the radioactivity incorporated into both alpha- and
LH beta-subunits after a 5-h incubation period. Cycloheximide completely
inhibited [35S]Met incorporation in the absence or presence of GnRH,
whereas actinomycin D only prevented the stimulatory effect of GnRH on this
incorporation. The increase of potassium ion concentration in the medium to
59 mM was without any effect on the synthesis of LH subunits. These data
demonstrate that GnRH specifically stimulates synthesis of the polypeptide
chains of LH and suggest that GnRH action is mediated by RNA synthesis.
Whether the expression of specific messenger RNAs encoding the LH subunits
is affected by GnRH is now under investigation.
