INFERTILITY may occur when a specific protein is not present in eggs, according to a study by researchers at the University of California, California, USA. The finding that when eggs in mice do not contain the protein called ZFP36L2, or L2 for short, they cannot be fertilised by sperm, could help researchers understand the causes of unexplained cases of infertility in human females.
Infertility in L2-Deficient Eggs
In the study, 10 female mice engineered to completely lack the L2 protein just in their eggs and 10 normal female mice were set up with an equal number of fertile male mice and tracked for a period of 6 months. While the normal female mice gave birth regularly, producing a litter approximately every 21 days, the mice lacking the L2 protein in their eggs didn’t produce a single pup.
The team discovered that this could be caused by the fact that the L2-deficient eggs were unable to undergo global transcriptional silencing, a vital step in creating a good egg in animals; the eggs lacking L2 continued transcribing genes into mRNA and producing proteins. The researchers also believe that other factors influencing infertility could be affected by L2.
Hope for Couples Unable to Conceive
The findings have uncovered a new area for researchers in this field to look at, which could ultimately lead to solutions for many human couples currently unable to conceive. “In my clinical practice, I work with couples struggling with infertility,” said senior author Dr Heidi Cook-Anderson, University of California. “It’s frustrating that for many of them, we have no idea why it’s difficult for them to conceive. All of their tests come back normal, but there are many things important for fertility that we still haven’t discovered. And we can’t test what we don’t know. That’s why this study is so important to us. It’s another clue.”
The team now want to undertake another study to establish whether L2 affects infertility in humans. In addition to potentially improving knowledge of human infertility, the results suggest that L2 and mRNA decay have an impact on global transcriptional silencing; this is something the researchers are currently looking further into in the mouse model.
James Coker, Reporter
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