Warren symposium follows legacy of geneticist giant

If we want to understand how the brain creates memories, and how genetic disorders distort the brain’s machinery, then the fragile X gene is an ideal place to start. That’s why the Stephen T. Warren Memorial Symposium, taking place November 28-29 at Emory, will be a significant event for those interested in neuroscience and genetics. Stephen T. Warren, 1953-2021 Warren, the founding chair of Emory’s Department of Human Genetics, led an international team that discovered Read more

Mutations in V-ATPase proton pump implicated in epilepsy syndrome

Why and how disrupting V-ATPase function leads to epilepsy, researchers are just starting to figure Read more

Tracing the start of COVID-19 in GA

At a time when COVID-19 appears to be receding in much of Georgia, it’s worth revisiting the start of the pandemic in early 2020. Emory virologist Anne Piantadosi and colleagues have a paper in Viral Evolution on the earliest SARS-CoV-2 genetic sequences detected in Georgia. Analyzing relationships between those virus sequences and samples from other states and countries can give us an idea about where the first COVID-19 infections in Georgia came from. We can draw Read more
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AEP

Drug discovery: Alzheimer’s and Parkinson’s spurred by same enzyme

Alzheimer’s disease and Parkinson’s disease are not the same. They affect different regions of the brain and have distinct genetic and environmental risk factors.

But at the biochemical level, these two neurodegenerative diseases start to look similar. That’s how Emory scientists led by Keqiang Ye, PhD, landed on a potential drug target for Parkinson’s.

Keqiang Ye, PhD

In both Alzheimer’s (AD) and Parkinson’s (PD), a sticky and sometimes toxic protein forms clumps in brain cells. In AD, the troublemaker inside cells is called tau, making up neurofibrillary tangles. In PD, the sticky protein is alpha-synuclein, forming Lewy bodies. Here is a thorough review of alpha-synuclein’s role in Parkinson’s disease.

Ye and his colleagues had previously identified an enzyme (asparagine endopeptidase or AEP) that trims tau in a way that makes it both more sticky and more toxic. In addition, they have found that AEP similarly processes beta-amyloid, another bad actor in Alzheimer’s, and drugs that inhibit AEP have beneficial effects in Alzheimer’s animal models.

In a new Nature Structural and Molecular Biology paper, Emory researchers show that AEP acts in the same way toward alpha-synuclein as it does toward tau.

“In Parkinson’s, alpha-synuclein behaves much like Tau in Alzheimer’s,” Ye says. “We reasoned that if AEP cuts Tau, it’s very likely that it will cut alpha-synuclein too.”

A particular chunk of alpha-synuclein produced by AEP’s scissors can be found in samples of brain tissue from patients with PD, but not in control samples, Ye’s team found.

In control brain samples AEP was confined to lysosomes, parts of the cell with a garbage disposal function. But in PD samples, AEP was leaking out of the lysosomes to the rest of the cell.

The researchers also observed that the chunk of alpha-synuclein generated by AEP is more likely to aggregate into clumps than the full length protein, and is more toxic when introduced into cells or mouse brains. In addition, alpha-synuclein mutated so that AEP can’t cut it is less toxic. Read more

Posted on July 12, 2017 by Quinn Eastman in Neuro Leave a comment

Amyloid vs tau? With this AD target, no need to choose

Keqiang Ye’s lab at Emory recently published a paper in Nature Communications that offers a two for one deal in Alzheimer’s drug discovery.

Periodically we hear suggestions that the amyloid hypothesis, the basis of much research on Alzheimer’s disease, is in trouble. Beta-amyloid is a toxic protein fragment that accumulates in extracellular brain plaques in Alzheimer’s, and genetics for early-onset Alzheimer’s point to a driver role for amyloid too.

In mice, inhibiting AEP hits two targets (amyloid and tau) with one shot

Unfortunately, anti-amyloid agents (either antibodies that sop up beta-amyloid or drugs that steer the body toward making less of it) have not shown clear positive effects in clinical trials.

That may be because the clinical trials started too late or the drugs weren’t dosed/delivered right, but there is a third possibility: modifying amyloid by itself is not enough.

Ye’s lab has been investigating an enzyme called AEP (asparagine endopeptidase), which he provocatively calls “delta secretase.” AEP is involved in processing both amyloid and tau, amyloid’s intracellular tangle-forming counterpart. Read more

Posted on May 16, 2017 by Quinn Eastman in Neuro Leave a comment

The secrets of a new Alzheimer’s secretase

The title of Keqiang Ye’s recent Nature Communications paper contains a provocative name for an enzyme: delta-secretase.

Just from its name, one can tell that a secretase is involved in secreting something. In this case, that something is beta-amyloid, the toxic protein fragment that tends to accumulate in the brains of people with Alzheimer’s disease.

Aficionados of Alzheimer’s research may be familiar with other secretases. Gamma-secretase was the target of some once-promising drugs that failed in clinical trials, partly because they also inhibit Notch signaling, important for development and differentiation in several tissues. Now beta-secretase inhibitors are entering Alzheimer’s clinical trials, with similar concerns about side effects.

Many Alzheimer’s researchers have studied gamma- and beta-secretases, but a review of the literature reveals that so far, only Ye and his colleagues have used the term delta-secretase.

This enzyme previously was called AEP, for asparagine endopeptidase. AEP appears to increase activity in the brain with aging and cleaves APP (amyloid precursor protein) in a way that makes it easier for the real bad guy, beta-secretase, to produce bad beta-amyloid.*At Alzforum, Jessica Shugart describes the enzyme this way:

Like a doting mother, AEP cuts APP into bite-sized portions for toddler BACE1 [beta-secretase] to chew on, facilitating an increase in beta-amyloid production. Read more

Posted on December 3, 2015 by Quinn Eastman in Neuro Leave a comment