M. Eramaa et al., INHIBIN ACTIVIN SUBUNIT MESSENGER-RNA EXPRESSION IN HUMAN GRANULOSA-LUTEAL CELLS, Molecular and cellular endocrinology, 92(2), 1993, pp. 15-20
We studied the expression of inhibin/activin subunit mRNAs in granulos
a-luteal cells of preovulatory ovarian follicles obtained from women u
ndergoing in vitro fertilization, and in corpus luteum tissue samples
of early pregnancy. Northern analysis of granulosa-luteal cell and cor
pus luteum RNA with single-stranded cDNA or cRNA probes revealed an 1.
6-kb mRNA for the alpha subunit and about 6.0-, 4.0-, 2.8-, and 1.7-kb
transcripts for the beta(A) subunit. No clear hybridization signal fo
r the beta(B) subunit could be detected. The relative expression level
s of alpha and beta(A) subunit mRNAs were determined at 2-day interval
s in granulosa-luteal cells cultured for 5 to 11 days. The levels of a
lpha subunit mRNAs declined steadily with increasing culture age, wher
eas those of beta(A) remained unchanged. Reverse transcription-polymer
ase chain reaction analysis with 35 amplification cycles confirmed the
expression of alpha and beta(A) subunit mRNAs in cultured granulosa-l
uteal cells. The beta(B) transcripts were also weakly detectable by th
is sensitive assay. In situ hybridization of human early pregnancy cor
pus luteum revealed intense hybridization with the alpha cRNA probe an
d a weaker signal for the beta(A) subunit in the granulosa cell compar
tment. We conclude that: (1) the inhibin alpha and beta(A) subunits (a
nd to a lesser extent beta(B)) are expressed in cultured human granulo
sa-luteal cells; (2) during extended culture periods the alpha/beta(A)
mRNA expression ratio decreases; and that (3) the alpha and beta(A) s
ubunit mRNA expression is observed in the granulosa cell compartment o
f early pregnancy corpora lutea.