Human chorionic gonadotropin (hCG) and hyperglycosylated hCG: the mediators that control human pregnancy

Abstract

There are two independent variants of human chorionic gonadotropin (hCG) with totally independent functions. Both forms share the 92 amino acid α-subunit and the 145 amino acid β-subunit. Regular hCG is a hormone with eight sugar side chains, four biantennary N-linked sugar structures and four trisaccharide O-linked sugar structures (molecular weight: 36,700). Hyperglycosylated hCG is an autocrine with eight sugar side chains, four triantennary N-linked oligosaccharides and four hexasaccharide O-linked oligosaccharides (molecular weight: 40,500). Hyperglycosylated hCG is produced by cytotrophoblast cells and regular hCG is formed by fused differentiated syncytiotrophoblast cells. These two molecules together coordinate most aspects of pregnancy. Research over the past 40 years has demonstrated that regular hCG promotes progesterone production by the corpus luteum, promotes angiogenesis of uterine spiral arteries, inhibits macrophage rejection of the implanting placenta, promotes growth of the umbilical co...