Association of human follitropin (FSH) receptor with splicing variant of human lutropin/choriogonadotropin receptor negatively controls the expression of human FSH receptor.
A splice variant of human lutropin (LH)/choriogonadotropin (CG)-receptor [hLHR(exon 9)] that lacks exon 9 was previously cloned in the corpus luteum of a woman with a normal menstrual cycle. Supported by a detergent-soluble binding assay and a receptor biotinylation experiment, the receptor binding assay shows hLHR(exon 9) is neither expressed at the cell surface nor has the capability of binding to hCG. In addition, hLHR(exon 9) was confirmed in the endoplasmic reticulum (ER) by endoglycosidase H treatment. A coimmunoprecipitation experiment clearly showed that hLHR(exon 9) and constitutively inactivate mutant-LHRs, which stay in the ER, form an association with the human follitropin (FSH)-receptor (hFSHR). This suggests that in the presence of mutant-LHR, hFSHR, which is trapped in the ER and associated with hLHR(exon 9), is unable to come up to the plasma membrane. This phenomenon is specific among gonadotropin receptors because human TSH receptor failed to be coimmunoprecipitated. Furthermore, this receptor complex attenuated the hFSHR receptor protein level within the cells, which impaired cAMP production. To elucidate the mechanism underlying the decrease in hFSHR protein by this receptor complex, we performed a Percoll fractionation experiment, which indicated that the receptor complex drove hFSHR to the lysosome instead of the plasma membrane. These results reveal a novel mechanism of FSHR expression regulation.
Yamashita
Soichi
S
Department of Obstetrics and Gynecology, School of Medicine, Gunma University, Gunma 371-8511, Japan.
Nakamura
Kazuto
K
Omori
Yuki
Y
Tsunekawa
Katsuhiko
K
Murakami
Masami
M
Minegishi
Takashi
T
D017398:Alternative Splicing; D019921:Biotinylation; D015153:Blotting, Western; D002460:Cell Line; D000242:Cyclic AMP / Q000378:metabolism; D018076:DNA, Complementary / Q000378:metabolism; D003902:Detergents / Q000494:pharmacology; D004591:Electrophoresis, Polyacrylamide Gel; D004721:Endoplasmic Reticulum / Q000378:metabolism; D005091:Exons; D005260:Female; D005786:Gene Expression Regulation; D005822:Genetic Vectors; D006026:Glycoside Hydrolases / Q000494:pharmacology; D006031:Glycosylation; D006801:Humans; D047468:Immunoprecipitation; D008247:Lysosomes / Q000378:metabolism; D008597:Menstrual Cycle; D009154:Mutation; D010053:Ovary / Q000378:metabolism; D010957:Plasmids / Q000378:metabolism; D011485:Protein Binding; D017510:Protein Folding; D012333:RNA, Messenger / Q000378:metabolism; D011962:Receptors, FSH / Q000737:chemistry* / Q000378:metabolism; D011974:Receptors, LH / Q000737:chemistry* / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013347:Subcellular Fractions; D014162:Transfection
D018076:DNA, Complementary; D003902:Detergents; D012333:RNA, Messenger; D011962:Receptors, FSH; D011974:Receptors, LH; D000242:Cyclic AMP; D006026:Glycoside Hydrolases