Washington: When sperm are constantly replenished in the adult male body, why does fertility in men diminish with age?
Chinese researchers have found that stimulating the metabolism of stem cells that produce sperms in male body can shed light on new ways to treat infertility in men.
The study was published in the journal of Genes and Development.
"So-called Myc genes, which play an important role in stem cells' ability to self-renew," said Takashi Shinohara Kyoto University' in China, who is interested specifically in spermatogonial stem cells (SSCs), which are responsible for producing sperm.
Shinohara added that SSCs are unique, because they are "the only stem cells that transmit genetic information to offspring."
The Shinohara lab demonstrates how the Myc gene regulates the self-renewal of mouse SSCs, via a process of glycolysis control. Glycolysis is a key part of cells' energy-making mechanism.
They injected two types of SSCs into mouse testes: normal cells in some and Myc gene-suppressed in others.
Two months later, they found that the total number of abnormal SSCs was far fewer than normal ones.
Gene analysis showed that the capacity for self-renewal had been compromised, with possibly important implications for sperm production in these mice.
"We found changes in the expression of genes that would slow the cell cycle," Shinohara stated.
In other words, suppressed SSCs could self-renew, but at a slower than normal rate.
"Stimulating the metabolism of SSCs could improve their proliferation. However, more careful study of the molecular pathways is necessary," Shinohara added.
Further study showed that this diminished rate was accompanied by impaired glycolysis, suggesting that the cells were not generating sufficient energy.
"These findings could have important implications for infertility research in the future," Shinohara noted.