Evidence for cycle-dependent expression of full-length human chorionic gonadotropin/luteinizing hormone receptor mRNA in human endometrium and decidua.

OBJECTIVE: To investigate the expression of full-length and truncated hCG/LH-receptor mRNA in human endometrium and decidua.
DESIGN: In vitro experiment.
SETTING: Tertiary university center. PATIENT(S): Premenopausal women undergoing hysterectomy because of benign diseases or induced abortions. INTERVENTION(S): Isolation of RNA from endometrial samples, reverse transcription, selective preamplification of full-length hCG/LH receptor mRNA and several shorter fragments of the receptor gene (exons 1-11, 1-10, and 1-5), nested polymerase chain reaction with internal primers. MAIN OUTCOME MEASURE(S): Appropriately sized cDNA product confirmed by sequencing. RESULT(S): All samples derived from the proliferative as well as from the early and mid-luteal phases were positive for all four amplification products, suggesting the expression of a full-length hCG/LH receptor mRNA. Only 5 of 8 samples derived from the late secretory phase and 2 of 12 samples derived from early decidua amplified the entire receptor sequence. In contrast, the shortest fragment (exons 1-5), coding for part of the extracellular receptor domain, was amplified in all samples. CONCLUSION(S): The data suggest cycle-dependent regulation of hCG/LH-receptor mRNA by changes in the alternative splicing pattern and down-regulation of full-length hCG/LH receptor mRNA in early decidua. The major splicing site appears to be located between introns 5 and 9. Alternative splicing may be a mechanism regulating hCG/LH-receptor down-regulation.