Tiny RNA Molecules Control Labor, May Be Key To Blocking Premature Birth

Tiny molecules called microRNAs act together with hormones to control the onset of labor, raising the prospect that RNA-based drugs might be able to prevent premature labor, researchers at UT Southwestern Medical Center have discovered in a preclinical study.

Using pregnant mice as well as human uterine tissue, the researchers uncovered a feedback cycle involving microRNAs, proteins called ZEB1 and ZEB2, and the pregnancy-maintaining hormone progesterone, as well as genes and other factors that control contraction of the uterus.

In the new study, the researchers measured microRNA levels in the uteri of mice in mid-pregnancy and near labor. As labor approached, the level of a group of microRNAs called the miR-200 family greatly increased. When the researchers artificially stimulated premature labor, the miR-200 levels also increased.

The miR-200s block the production of two proteins called ZEB1 and ZEB2. In contrast, progesterone directly increases ZEB1 levels. The researchers uncovered a feedback cycle involving all these factors that prevents uterine contraction as long as progesterone is present.

The researchers directly tested the contractility of cultured human uterine cells containing low or high levels of ZEB1 or ZEB2. In the presence of oxytocin, uterine cells with low levels of ZEBs contracted, while those with high levels did not, mirroring what happened in the pregnant mice.

This could possibly provide us with an answer to premature pregnancies and thus reduce significant the complications that can occur during a premature pregnancy. The baby will be able to develop completely in the mother's uterus and this could also help the mother's  bodies get more prepared for pregnancy. However, more research does need to be conducted before this method is to be used on the public.