Expression of leucine-rich repeat-containing G-protein-coupled receptors in the human cyclic endometrium.
OBJECTIVE
To study the mRNA expression of the two leucine-rich repeat-containing G-protein-coupled receptors LGR-4 and LGR-5 and the mRNA and protein expression of LGR-7, the relaxin receptor, in the human cyclic endometrium.


METHODS
Retrospective study.


METHODS
Department of Anatomy and Reproductive Biology, Rheinisch-Westfälische Technische Hochschule Aachen, Aachen, Germany.


METHODS
LGR-4, -5, and -7 mRNA expression was assessed by semiquantitative and real time reverse transcription-polymerase chain reaction in the endometrium of premenopausal women (n = 26) and cultured primary endometrial epithelial cells and fibroblasts (n = 3). Transcript size was determined by Northern blotting. LGR-7 protein expression was assessed by immunohistochemistry.


RESULTS
The mRNA of LGR-4, LGR-5, and LGR-7 was expressed constitutively throughout the menstrual cycle in the endometrium, and characterized by substantial differences in expression levels of individual women. LGR-7 immunostaining was detected in the epithelium of the functional layer throughout the cycle, with lowest staining in the midproliferative phase. Furthermore, individual stromal cells of the functional layer and the stroma of the basal layer showed LGR-7 immunostaining.


CONCLUSIONS
Endometrial expression of the mRNA of orphan receptors LGR-4 and LGR-5 implies that the endometrium is potentially influenced by as yet unknown mediators, which are possibly involved in fertility control. Furthermore, we confirmed constitutive endometrial mRNA expression of LGR-7, the classical relaxin receptor, and demonstrated specific LGR-7 immunostaining of different endometrial cell types, which suggests a physiological role of relaxin in the human endometrium.
Krusche
Claudia A
CA
Department of Anatomy and Reproductive Biology, Rheinisch-Westfälische Technische Hochschule Aachen, Aachen, Germany. ckrusche@ukaachen.de <ckrusche@ukaachen.de>
Kroll
Tina
T
Beier
Henning M
HM
Classen-Linke
Irmgard
I
D000595:Amino Acid Sequence; D015152:Blotting, Northern; D018929:Cell Culture Techniques; D004717:Endometrium / Q000166:cytology* / Q000502:physiology*; D005260:Female; D006801:Humans; D007930:Leucine; D008565:Membrane Proteins / Q000235:genetics*; D008597:Menstrual Cycle; D009693:Nucleic Acid Hybridization; D043562:Receptors, G-Protein-Coupled / Q000235:genetics*; D018000:Receptors, Peptide; D012016:Reference Values; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014158:Transcription, Genetic; D014599:Uterus / Q000166:cytology / Q000502:physiology
C411562:LGR4 protein, human; C116884:LGR5 protein, human; D008565:Membrane Proteins; C417543:RXFP1 protein, human; C472867:RXFP2 protein, human; D043562:Receptors, G-Protein-Coupled; D018000:Receptors, Peptide; D007930:Leucine