A new study from Washington University School of Medicine in St. Louis identifies a specific gene’s previously unknown role in fertility. When the gene is missing in fruit flies, roundworms, zebrafish and mice, the animals are infertile or lose their fertility unusually early but appear otherwise healthy. Analyzing genetic data in people, the researchers found an association between mutations in this gene and early menopause.
The study appeared in the journal Science Advances.
The human gene, called nuclear envelope membrane protein 1 (NEMP1), is not widely studied. In animals, mutations in the equivalent gene had been linked to impaired eye development in frogs. The researchers who made the new discovery were not trying to study fertility at all. Rather, they were using genetic techniques to find genes involved with eye development in the early embryos of fruit flies.
“We blocked some gene expression in fruit flies but found that their eyes were fine,” said senior author Helen McNeill, PhD, the Larry J. Shapiro and Carol-Ann Uetake-Shapiro Professor and a BJC Investigator at the School of Medicine. “So, we started trying to figure out what other problems these animals might have. They appeared healthy, but to our surprise, it turned out they were completely sterile. We found they had substantially defective reproductive organs.”
Though it varied a bit by species, males and females both had fertility problems when missing this gene. And in females, the researchers found that the envelope that contains the egg’s nucleus — the vital compartment that holds half of an organism’s chromosomes — looked like a floppy balloon. “It’s interesting to ask whether stiffness of the nuclear envelope of the egg is also important for fertility in people,” McNeill said. “If you have a softer nucleus, maybe it can’t handle that environment. This could be the cue that triggers the death of eggs. We don’t know yet, but we’re planning studies to address this question.”