The multiple “litter” births of mice, versus the normal singleton pregnancy of humans, is due to defective processing in mice of a common mammalian protein called bone morphogenetic protein 15 (BMP-15), according to new research from the University of California, San Diego (UCSD) School of Medicine.
Published online the week of April 4, 2005 in Proceedings of the National Academy of Sciences, and appearing in the journal’s April 12, 2005 print edition, the study provides one of the first insights into the physiological mechanisms responsible for multiple births and suggests a potential therapeutic target for infertility and contraception.
“Infertility is a major problem for many couples,” said the study’s senior author, Shunichi Shimasaki, Ph.D., UCSD professor of reproductive medicine. “Based on our findings, it is possible that therapeutic regimens targeting BMP-15 could offer exciting new opportunities for novel treatments for female infertility. On the other side of the coin, BMP-15 could also serve as a new target for non-steroidal contraceptives.”
Recently, scientists have found that BMP-15 produced by eggs developing in the ovary plays an important role in determining ovulation quota, which results in litter size in mammals. In laboratory studies with human and mouse models, the UCSD team found specific differences between mice and humans in the way BMP-15 is produced and secreted by cells.