Implantation-dependent expression of trophinin by maternal fallopian tube epithelia during tubal pregnancies: possible role of human chorionic gonadotrophin on ectopic pregnancy.
Trophinin, tastin, and bystin have been identified as molecules potentially involved in human embryo implantation. Both trophoblasts and endometrial epithelial cells express trophinin, which mediates apical cell adhesion through homophilic trophinin-trophinin binding. We hypothesized that trophinin's function in embryo implantation is unique to humans and investigated the expression of trophinin, tastin, and bystin in ectopic pregnancy, a condition unique to humans. In tubal pregnancies, high levels of all three were found in both trophoblasts and fallopian tubal epithelia. Trophinin expression in maternal cells was particularly high in the area adjacent to the trophoblasts, whereas trophinin was barely detectable in intact fallopian tubes from women with in utero pregnancies or without pregnancies. When explants of intact fallopian tube were incubated with the human chorionic gonadotrophin (hCG), trophinin expression was enhanced in epithelial cells. Since the trophectoderm of the human blastocyst secretes hCG before and after implantation, these results suggest that hCG from the human embryo induces trophinin expression by maternal cells. As both beta-subunit of hCG and trophinin genes have diverged in mammals, the present study suggests a unique role of hCG and trophinin in human embryo implantation, including the pathogenesis of ectopic pregnancy.
Nakayama
Jun
J
Departments of Pathology, Internal Medicine, Surgery, and Laboratory Medicine, Shinshu University School of Medicine, Matsumoto, Japan. jun@hsp.md.shinshu-u.ac.jp
Aoki
Daisuke
D
Suga
Tomoaki
T
Akama
Tomoya O
TO
Ishizone
Satoshi
S
Yamaguchi
Hirohito
H
Imakawa
Kazuhiko
K
Nadano
Daita
D
Fazleabas
Asgerally T
AT
Katsuyama
Tsutomu
T
Nozawa
Shiro
S
Fukuda
Michiko N
MN
D000328:Adult; D015815:Cell Adhesion Molecules / Q000235:genetics / Q000378:metabolism*; D006063:Chorionic Gonadotropin / Q000378:metabolism* / Q000494:pharmacology; D002824:Chorionic Villi; D010064:Embryo Implantation; D004847:Epithelial Cells / Q000187:drug effects / Q000378:metabolism; D005187:Fallopian Tubes / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D005260:Female; D006801:Humans; D008875:Middle Aged; D011247:Pregnancy; D011274:Pregnancy, Tubal / Q000378:metabolism*; D012333:RNA, Messenger / Q000378:metabolism; D014327:Trophoblasts
C112245:BYSL protein, human; D015815:Cell Adhesion Molecules; D006063:Chorionic Gonadotropin; D012333:RNA, Messenger; C093649:TRO protein, human; C093648:TROAP protein, human