TY - JOUR
T1 - D1-Receptor, DARPP-32, and PP-1 in the primate Corpus luteum and luteinized granulosa cells
T2 - Evidence for phosphorylation of DARPP-32 by dopamine and human chorionic gonadotropin
AU - Mayerhofer, Artur
AU - Fritz, Stephanie
AU - Grünert, Robert
AU - Sanders, Sheryl L.
AU - Duffy, Diane M.
AU - Ojeda, Sergio R.
AU - Stouffer, Richard L.
PY - 2000
Y1 - 2000
N2 - The multifunctional phosphoprotein "dopamine and cAMP-related phosphoprotein, Mr 32,000" (DARPP-32), which is able to act as an intracellular third messenger, was previously found to be present in human luteinized granulosa cells (GCs) and human ovary. DARPP-32 phosphorylation in GCs was increased by dopamine (DA) acting via a DA-1 receptors (D1-R). In the present study, we examined whether the major endocrine signaling molecule for GCs, LH/human CG (hCG), could also affect DARPP-32 phosphorylation. Immunoprecipitation studies showed that hCG, as well as DA, increased phosphorylation of DARPP-32 at threonine residues within 10 min, indicating that the signal transduction pathways of a hormone and a neurotransmitter involve DARPP-32 in GCs. Phosphorylated DARPP-32 is known to inhibit a cellular phosphatase (PP-1), which was also found to be expressed by GCs. Using RT-PCR and sequence analyses we showed that DARPP-32, PP-1, and D1-R genes were not restricted to cultured luteinized GCs, but were expressed in vivo, in the corpus luteum (CL) of the rhesus monkey throughout its entire life span. Whereas hCG increased steroid production in monkey luteinized GCs and in isolated luteal cells, DA failed to affect basal or hCG-stimulated progesterone production. This indicates that, unlike the LH/hCG receptor, the D1-R is not directly linked to steroid production. Although the precise role of D1-R in the CL remains to be shown, the presence of D1-R, DARPP-32, and its target PP-1 in this endocrine tissue, as well as the phosphorylation of DARPP-32 by a gonadotropin and by DA in luteinized GCs, indicate that the signal transduction pathways of the neurotransmitter DA and the gonadotropin hCG/LH involve DARPP-32. The PP-1 inhibitor DARPP-32 may, thus, be a third messenger used by both DA and hCG/LH to exert common regulatory influences on the cells of the CL.
AB - The multifunctional phosphoprotein "dopamine and cAMP-related phosphoprotein, Mr 32,000" (DARPP-32), which is able to act as an intracellular third messenger, was previously found to be present in human luteinized granulosa cells (GCs) and human ovary. DARPP-32 phosphorylation in GCs was increased by dopamine (DA) acting via a DA-1 receptors (D1-R). In the present study, we examined whether the major endocrine signaling molecule for GCs, LH/human CG (hCG), could also affect DARPP-32 phosphorylation. Immunoprecipitation studies showed that hCG, as well as DA, increased phosphorylation of DARPP-32 at threonine residues within 10 min, indicating that the signal transduction pathways of a hormone and a neurotransmitter involve DARPP-32 in GCs. Phosphorylated DARPP-32 is known to inhibit a cellular phosphatase (PP-1), which was also found to be expressed by GCs. Using RT-PCR and sequence analyses we showed that DARPP-32, PP-1, and D1-R genes were not restricted to cultured luteinized GCs, but were expressed in vivo, in the corpus luteum (CL) of the rhesus monkey throughout its entire life span. Whereas hCG increased steroid production in monkey luteinized GCs and in isolated luteal cells, DA failed to affect basal or hCG-stimulated progesterone production. This indicates that, unlike the LH/hCG receptor, the D1-R is not directly linked to steroid production. Although the precise role of D1-R in the CL remains to be shown, the presence of D1-R, DARPP-32, and its target PP-1 in this endocrine tissue, as well as the phosphorylation of DARPP-32 by a gonadotropin and by DA in luteinized GCs, indicate that the signal transduction pathways of the neurotransmitter DA and the gonadotropin hCG/LH involve DARPP-32. The PP-1 inhibitor DARPP-32 may, thus, be a third messenger used by both DA and hCG/LH to exert common regulatory influences on the cells of the CL.
UR - http://www.scopus.com/inward/record.url?scp=0034485864&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=0034485864&partnerID=8YFLogxK
U2 - 10.1210/jcem.85.12.7084
DO - 10.1210/jcem.85.12.7084
M3 - Article
C2 - 11134138
AN - SCOPUS:0034485864
SN - 0021-972X
VL - 85
SP - 4750
EP - 4757
JO - Journal of Clinical Endocrinology and Metabolism
JF - Journal of Clinical Endocrinology and Metabolism
IS - 12
ER -