A key enzyme that significantly increases the risk of neural tube defects such as spina bifida and some heart defects among babies born to women with diabetes has been identified.
A team at Joslin Diabetes Center, headed by Mary R. Loeken, PhD, say that the enzyme AMP kinase (AMPK) could lead to strategies to interfere with the mechanism and reduce the chances of such birth defects occurring.
Even if women with diabetes-either type 1 or type 2 -- work vigilantly to control their blood sugar levels around the time of conception, the risk of a defect is still twice that of the general population.
Previous studies published by Loeken's lab showed that maternal hyperglycemia (high blood sugar) causes oxidative stress in the embryo, and inhibits expression of the Pax3 gene. Pax3 is essential to the formation of the neural tube, which in the embryo is the precursor to the brain and spinal cord.
However, Loeken said, it was not known how the cells that express Pax3 could sense the oxidative stress and why oxidative stress, which occurs throughout the embryo, only damages selective structures such as the neural tube.
In their new study, Loeken's team identified the key to the process as AMP kinase, which is activated by oxidative stress and was found to signal the cell nucleus to block the expression of Pax3.
"The stimulation of a metabolism-sensing enzyme that can regulate specific genes explains how oxidative stress, which is generated throughout the embryo during maternal hyperglycemia, causes malformation of specific embryo structures," Loeken said.
"We now know that we must do whatever we can to prevent AMPK from being stimulated," said Loeken, who is a research investigator in Joslin's Section on Islet Cell and Regenerative Biology.
Trying to keep the mother's blood glucose levels under control is currently the only way to do that, she noted. "That's the best we can do right now," she said. But armed with the findings of this study, she noted, other researchers may be able to come up with drugs or other strategies to inhibit AMPK activity,
The study was recently published in the journal Diabetologia.