Canine preprorelaxin: nucleic acid sequence and localization within the canine placenta

• Published in: Biology of reproduction Vol. 60; no. 3; pp. 551 - 557
• Main Authors: Klonisch, T, Hombach-Klonisch, S, Froehlich, C, Kauffold, J, Steger, K, Steinetz, B.G, Fischer, B
• Format: Journal Article
• Language: English
• Published: Madison, WI Society for the Study of Reproduction 01-03-1999
• Subjects: Allantois - chemistry; Amino Acid Sequence; amino acid sequences; Animals; Base Sequence; Binding Sites; Biological and medical sciences; Chorion - chemistry; Chorionic Villi - chemistry; cloning; complementary DNA; DNA, Complementary - chemistry; Dogs; Embryology: invertebrates and vertebrates. Teratology; Female; Fetal membranes; Fundamental and applied biological sciences. Psychology; General aspects. Development. Fetal membranes; Horses; immunohistochemistry; In Situ Hybridization; localization; messenger RNA; Molecular Sequence Data; nucleotide sequences; placenta; Placenta - chemistry; placental synctiotrophoblast; precursors; Pregnancy; Protein Precursors - analysis; Protein Precursors - chemistry; Protein Precursors - genetics; Receptors, G-Protein-Coupled; Receptors, Peptide - metabolism; relaxin; Relaxin - analysis; Relaxin - chemistry; Relaxin - genetics; RNA, Messenger - analysis; Sequence Homology; Swine; Fissipedia; Carnivora; Nucleotide sequence; Fetal membrane; Gene expression; Relaxin; Ovarian hormone; Vertebrata; Mammalia; Placenta; Molecular cloning; Localization; Dog
• ISSN: 0006-3363; 1529-7268
• DOI: 10.1095/biolreprod60.3.551

Employing uteroplacental tissue at Day 35 of gestation, we determined the nucleic acid sequence of canine preprorelaxin using
reverse transcription- and rapid amplification of cDNA ends-polymerase chain reaction. Canine preprorelaxin cDNA consisted
of 534 base pairs encoding a protein of 177 amino acids with a signal peptide of 25 amino acids (aa), a B domain of 35 aa,
a C domain of 93 aa, and an A domain of 24 aa. The putative receptor binding region in the N′-terminal part of the canine
relaxin B domain GRDYVR contained two substitutions from the classical motif (E→D and L→Y). Canine preprorelaxin shared highest
homology with porcine and equine preprorelaxin. Northern analysis revealed a 1-kilobase transcript present in total RNA of
canine uteroplacental tissue but not of kidney tissue. Uteroplacental tissue from two bitches each at Days 30 and 35 of gestation
were studied by in situ hybridization to localize relaxin mRNA. Immunohistochemistry for relaxin, cytokeratin, vimentin, and
von Willebrand factor was performed on uteroplacental tissue at Day 30 of gestation. The basal cell layer at the core of the
chorionic villi was devoid of relaxin mRNA and immunoreactive relaxin or vimentin but was immunopositive for cytokeratin and
identified as cytotrophoblast cells. The cell layer surrounding the chorionic villi displayed specific hybridization signals
for relaxin mRNA and immunoreactivity for relaxin and cytokeratin but not for vimentin, and was identified as syncytiotrophoblast.
Those areas of the chorioallantoic tissue with most intense relaxin immunoreactivity were highly vascularized as demonstrated
by immunoreactive von Willebrand factor expressed on vascular endothelium. The uterine glands and nonplacental uterine areas
of the canine zonary girdle placenta were devoid of relaxin mRNA and relaxin. We conclude that the syncytiotrophoblast is
the source of relaxin in the canine placenta.