In an important new development in the quest to develop better gene therapies that can treat a wide range of diseases, researchers from the University of Massachusetts Amherst and UMass Chan Medical School recently announced that they could increase the expression and maturation of the protein alpha-1 in mapped. antitrypsin (AAT) with unprecedented clarity. The results, describing the molecular folding of the protein, were published in the Proceedings of the National Academy of Sciences and will help develop specific therapies to treat an inherited disease known as alpha-1 antitrypsin deficiency, and more effectively treat a wide variety 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 host of diseases, such as AAT deficiency, that arise when our own bodies produce dysfunctional protein at the genetic level. The production of defective AAT or insufficient amounts of AAT can cause serious lung and liver disease. These diseases must be treated by either delivering the missing proteins to the body or, better still, teaching the body to make the missing proteins for itself by inserting an intact copy of the specific protein-producing gene into the DNA of the correct cell. to introduce.
But teaching the body to make a missing protein is no easy task. To do this, you first need to get the correct protein-producing gene into the body, usually through an intramuscular injection — an injection — and into the specific cells that make that protein. Then you have to make sure that once the body starts making the protein it was missing before, that protein is folded correctly into the correct, final shape -; in the case of AAT, that shape looks like a loaded mousetrap ready to be jumped. Finally, that correctly folded protein has to make its way from the cell to wherever in the body it is needed.
It’s an immensely complex set of problems that requires a research team with expertise in molecular biology, cell biology, protein folding and gene therapy, as well as advanced research facilities to conduct the work, such as the Models to Medicine Center at UMass Amherst’s Institute for Applied Life Sciences, where the laboratories are located where much of the research has been completed.
This project is the result of more than a decade of collaboration and spans from lab-based basic science to the bedside.”
Daniel Hebert, professor of biochemistry and molecular biology at UMass Amherst and one of the co-authors of the paper
The research was funded by the Alpha-1 Foundation and the National Institutes of Health.
Making a better mousetrap
It begins with Terence R. Flotte, the Celia and Isaac Haidak Professor, Executive Deputy Chancellor, Provost and Dean of 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 studies in which we inject AAV with the normal version of the AAT gene into the muscles to create a ‘sustained release’ of the protein in patients with AAT deficiency,” says Flotte. “But until now we didn’t understand how well the AAT protein was processed in the muscle at a biochemical level.”
However, not all body cells are able to make all the proteins the body needs. For example, AAT is best made in the liver. But since most injections take place in a muscle — think of the injections you get in your arm — the team had to figure out how muscle cells would act more like liver cells in their production of AAT, and how the AAT produced in the muscle to the lungs. and deliver where it is needed.
It turns out that Hebert is an expert on these questions, and after confirming that muscle cells are poor producers of AAT, he helped develop a technique that increases the secretion of AAT in muscle cells by about 50 percent using some sort of chemical. , known as a proteostasis regulator, called suberoylanilide hydroxamic acid or SAHA. “It’s a way of letting the muscles do some of the liver’s work,” he says.
And yet not all proteins are created equal. Their shape is crucial in determining how and whether a protein works as it should. The process of how a protein takes a specific shape, the so-called 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 they have to be metastable” – imagine a trap you just set and waiting for a mouse. “It’s a very special shape, and it has to be just right or the protein won’t work as it should.”
While the team has focused on AAT deficiency as a case study, their work shows that combinatorial treatments, which include both gene therapies and proteostasis regulators, can increase the efficacy 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 injection that could cure a very difficult, potentially devastating genetic condition. It takes a broad interdisciplinary team, with expertise drawn from both the lab and the patient has gained, to come up with an answer.”
University of Massachusetts Amherst
Gierasch, L., et al. (2022) Secretion of functional 1-antitrypsin is cell type dependent: implications for intramuscular delivery for gene therapy. PNAS. doi.org/10.1073/pnas.2206103119.