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Gene Linked to Infertility in Mice; Findings May Apply to Humans
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"In turn, these messenger RNAs control the process of sperm production. In short, the protein MIWI, which is encoded by this gene is a master protein responsible for turning genes on and off during the process of sperm formation," he said.
The testes of mice with a defective miwi gene were, on average, 29 percent smaller by weight and did not produce any sperm.
The research, which was funded by the National Institutes of Health and the David and Lucile Packard Foundation of Los Altos, California, uses gene knockout technology in which Lin bred a mouse lacking the miwi gene, which was linked to chromosome 5.
The miwi gene is a member of the piwi gene family identified by Lin in 1997. The piwi genes were first isolated in Drosophila, or fruit flies, and have since been linked to reproductive stem cell function, ovarian tumors and infertility in fruit flies. Lin found that by removing the gene in fruit flies, the reproductive stem cells, called germline stem cells, would be depleted.
Now, the same family of genes has been linked to infertility in male mice. Lin is confident that the gene infertility link he found in mice, will one day apply to humans.
"In Developmental Cell, we show that without this gene, or if there is an underactive form of the gene, infertility in mice is the end result. We've also shown this in fruit flies and nematodes. Given the evolutionary closeness between mice and humans, it is very likely that a defective hiwi gene will affect humans in the same manner as well," Lin said.
According to the National Institute of Child Health and Human Development (NICHD), there are approximately 2.6 million infertile married couples in the U.S. Male infertility is a factor in approximately 40 percent of those cases.
The study was co-authored by Wei Deng, a postdoctoral fellow in the Lin laboratory.
