Molecular picture of how antiviral drug molnupiravir works

A cryo-EM structure showing how the antiviral drug molnupiravir drug Read more

Straight to the heart: direct reprogramming creates cardiac “tissue” in mice

New avenues for a quest many cardiologists have pursued: repairing the damaged heart like patching a Read more

The future of your face is plastic

An industrial plastic stabilizer becomes a skin Read more

Bing Yao

Brain organoid model shows molecular signs of Alzheimer’s before birth

In a model of human fetal brain development, Emory researchers can see perturbations of epigenetic markers in cells derived from people with familial early-onset Alzheimer’s disease, which takes decades to appear. This suggests that in people who inherit mutations linked to early-onset Alzheimer’s, it would be possible to detect molecular changes in their brains before birth.

The results were published in the journal Cell Reports.

“The beauty of using organoids is that they allow us to trace back what could happen at the molecular level in early developmental stages,” says lead author Bing Yao, PhD, assistant professor of human genetics at Emory University School of Medicine. “A lot of epigenetic studies on Alzheimer’s use postmortem brains, which only represent the end point of the disease, in terms of molecular signatures.”

Photos of brain organoid cultures courtesy of Zhexing Wen

The brain organoid model allows scientists to probe human fetal brain development without poking into any babies; they have also been used to study schizophrenia, fragile X syndrome and susceptibility to Zika virus.

Co-author Zhexing Wen helped develop the model, in which human pluripotent stem cells recapitulate early stages of brain development, corresponding to 17-20 weeks after conception. The stem cell lines were obtained from both healthy donors and from people with mutations in PSEN1 or APP genes, which lead to early-onset Alzheimer’s.

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Posted on by Quinn Eastman in Uncategorized Leave a comment

Mysterious DNA modification important in fly brain

Emory scientists have identified a function for a mysterious DNA modification in fruit flies’ brain development, which may provide hints to its role in humans.

The results were published Thursday, August 2 in Molecular Cell.

Epigenetics may mean “above the genes,” but a lot of the focus in the field is on DNA methylation, a chemical modification of DNA itself. Methylation doesn’t change the actual DNA letters (A, C, G and T), but it does change how DNA is handled by the cell. Generally, it shuts genes off and is essential for cell differentiation.

The most commonly studied form of DNA methylation appears on the DNA letter C (cytosine). Drosophila, despite being a useful genetic model of development, have very little of this form of DNA methylation. What they do have is methylation on A — technically, N6-methyladenine, although little was known about what this modification did for flies.

Editor’s note: See this 2017 Nature feature from Cassandra Willyard on an “epigenetics gold rush”, which mentions the discovery of N6-methyladenine’s presence in the genomes of several organisms.

Emory geneticists Bing Yao, PhD, Peng Jin, PhD and colleagues now have shown that an enzyme that removes methylation from A is critical for neuronal development in Drosophila.

This finding is significant because the enzyme is in the same family (TET for ten-eleven translocation) of demethylases that trigger removal of DNA methylation from C in mammals. The function of TET enzymes, revealing that cells actively removed DNA methylation rather than just letting it slough off, was discovered only in 2009. Read more

Posted on by Quinn Eastman in Neuro Leave a comment