In a major new development in the quest to develop better gene therapies to treat a range of diseases, researchers at the University of Massachusetts Amherst and UMass Chan School of Medicine recently announced that they have mapped the expression and maturation of alpha-1 protein. antitrypsin (AAT) with unprecedented clarity. The results, which detail the molecular folding of the protein, were published in the Proceedings of the National Academy of Sciences and will help develop targeted therapies to treat an inherited disease known as alpha-1 antitrypsin deficiency, as well as more effectively treat a wide range of genetic diseases.
In recent years there has been a revolution in the treatment of diseases. It is now clear that there is a whole range of diseases, such as AAT deficiency, that arise when our own bodies produce dysfunctional proteins at the genetic level. Defective AAT production or inadequate amounts of AAT can cause serious lung and liver disease. These diseases must be treated either by delivering the missing proteins to the body or, even better, by teaching the body to make the missing proteins itself by inserting an intact copy of the specific protein-producing gene into the cell’s DNA. appropriate cell.
But teaching the body to make a missing protein is no easy task. To do this, the appropriate protein-producing gene must first be introduced into the body, usually through an intramuscular injection, and into the specific cells that produce that protein. Next, you need to make sure that once the body starts making the protein that was previously missing, that protein folds correctly into its proper final form; in the case of the AAT, this shape looks like a loaded mousetrap ready to be sprung. . Finally, this correctly folded protein must make its way from the cell to wherever it is needed in the body.
This is an enormously complex set of problems that requires a research team with expertise in molecular biology, cell biology, protein folding and gene therapy, as well as state-of-the-art research facilities to carry out the work, such as the Models to Medicine Center at UMass Amherst’s Institute for Applied Life Sciences, which houses the labs where much of the research was completed.
This project is the result of more than a decade of collaboration and spans the full range of laboratory-based basic science to the bedside.”
Daniel Hebert, professor of biochemistry and molecular biology at UMass Amherst and one of the paper’s co-authors
Funding for the research was provided by the Alpha-1 Foundation and the National Institutes of Health.
Making a better mousetrap
It begins with Terence R. Flotte, Professor Celia and Isaac Haidak, Executive Vice Chancellor, Provost and Dean of the TH Chan School of Medicine. Flotte, a pioneer in gene therapies, has developed a way to use the harmless adeno-associated virus, or AAV, as a vehicle to deliver gene therapies. “We have completed three clinical trials in which we inject AAV containing the normal version of the AAT gene into the muscle to create a ‘sustained release’ of the protein in AAT-deficient patients,” says Flotte. “But until now we didn’t understand how well the AAT protein was processed inside the muscle at the biochemical level.”
However, not all cells in the body are able to produce all the proteins that the body needs. AAT, for example, is best made in the liver. But since most firing occurs in a muscle—think of the firing you do in your arm—the team had to figure out how to get muscle cells to act more like liver cells in producing of AAT, and then how to achieve it. the AAT produced in the muscle to the lungs and liver where it is needed.
It turns out that Hebert is an expert on these very issues, and after confirming that muscle cells are poor producers of AAT, he helped develop a technique that increases AAT secretion in muscle cells by 50 % approximately by means of some kind of chemical substances. , known as a proteostasis regulator, called suberoylanilide hydroxamic acid or SAHA. “It’s a way to get the muscles to do some of the liver’s work,” he says.
And yet, not all proteins are created equal. Its shape is crucial to determining how, or whether, a protein functions as it should. The process of how a protein assumes a specific shape, called the protein folding problem, has been the focus of Lila Gierasch, distinguished professor of biochemistry and molecular biology at UMass Amherst, throughout her career.
“These protein molecules are absolutely fascinating,” says Gierasch. “They look like little mousetraps and must be metastable”-;imagine a trap you’ve just set and it’s waiting for a mouse. “It’s a very special shape and it has to be exactly right, or the protein won’t work the way it’s supposed to.”
Although the team focused on AAT deficiency as a case study, their work shows that combination treatments, including both gene therapies and proteostasis regulators, can increase the effectiveness of gene therapies , not only for AAT deficiency, but for many genetic disorders. more generally
“Our ultimate goal,” says Gierasch, “is to provide an easy vaccine that can cure a very difficult and potentially devastating genetic disorder. It takes a broadly interdisciplinary team, with expertise gathered from both the laboratory and the patient side, to come forward. with an answer.”
Source:
University of Massachusetts Amherst
Journal reference:
Gierasch, L., et al. (2022) Secretion of functional α1-antitrypsin is cell type dependent: implications for intramuscular delivery for gene therapy. PNAS. doi.org/10.1073/pnas.2206103119.