Objective
It is known that Type 1 Diabetes mellitus (T1D) is no longer a disease solely arising from an attack of the immune system against pancreatic beta (β)-cells. As such, there is evidence that disturbances in the stability of β-cells’ metabolism and overall functions play a relevant part in the development of the disease. The endoplasmic reticulum (ER) is one of the cellular structures accountable for this cellular stability and is, for example, responsible for calcium storage and protein processing. When this processing becomes saturated, the so-called ER stress occurs. Of notice, β-cells are naturally susceptible to high levels of stress due to their high demand for insulin production and secretion. Therefore, the main goal of this proposal is to search for genetic modifications that enable β-cell resistance against ER stress and mitigate the effects of the immune system action. Our preliminary data have already shown that by deleting two genes, Sec24 and Sec31a, β-cells become more resistant to both ER stress and immune cells destruction. Hence, we will first create mouse and human cells using different genetic engineering methods to obtain a complete understanding of the role of SEC24A and SEC31A in the progress of T1D. Sequentially, we will perform several experiments to investigate the influence of SEC24A and SEC31A on ER stress relief and recovery of cellular function, and the interaction between our genetically modified cells and the immune system.
Background Rationale
Beta (β)-cells are endocrine cells located in the islets of Langerhans in the pancreas and are responsible for the production and secretion of insulin, the hormone responsible for regulating blood sugar levels. In the past, Type 1 Diabetes (T1D) was solely attributed to attacks from the cells of the immune system against β-cells, which were regarded as victims in the course of the disease’s evolution. However, it is currently known that β-cells may present alterations that favor their own destruction, as briefly explained in the following lines. The endoplasmic reticulum (ER) is an important structure for regulating cell stability. It is the largest deposit of calcium (Ca2+) and is also responsible for protein processing. Over the past 15 years, studies have shown that ER disturbances, known as ER stress, directly contribute to β-cell failure in T1D. The normal physiology of β-cells includes high levels of ER stress due to their constant demand for the production and secretion of insulin in response to blood sugar levels. However, long periods of stress may cause changes in Ca2+ stock and inadequate protein processing in β-cells, which trigger some cellular mechanisms for restoring proper cellular functioning. However, during exacerbated stress these mechanisms may not be sufficient, resulting in cell death and/or abnormal production of proteins by the ER that may attract the immune system activity against β-cells. To this date, the mechanisms responsible for the unregulated production of proteins remain poorly understood. Therefore, in this proposal, we will strive to use genetic engineering to develop a protection strategy to enable β-cells to withstand or prevent exacerbated ER stress and, consequently, diminish the attack from the immune system.
Description of Project
Type 1 diabetes (T1D) is an autoimmune disease, which means immune cells become self-targeting and destroy the insulin-producing beta cells. Interestingly, recent studies shows that also the pancreatic beta (β)-cells may contribute to the development of T1D. The organelle, endoplasmic reticulum (ER), is a large structure responsible for many cellular functions, including calcium storage and protein processing. In beta cells, ER is responsible for insulin production. However, when insulin or other protein productions exceed the functional capacity of ER, a physiological cellular process named ER stress occurs, which would promote immune cell’s attack and ultimately lead to beta cell death. Therefore, we have been working on an scientific approach based on genetic engineering to search for gene that may protect β-cell against ER stress. Our research results show that two genes, named Sec24 and Sec31a, play a critical role in controlling β-cells ER stress response. Then, the goal of this proposal is to obtain a deeper understanding of the role of SEC24A and SEC31A in the progress of β-cell in T1D development. With this knowledge, we aim to develop a new therapeutic strategy for β-cell protection. We will validate these two genes’ function in beta cell ER stress response and autoimmune protection using human and mouse beta cells . Overall, our results will provide a wealth of data to understand the role of SEC24A and SEC31A in beta cells, which would be a potential treatment for T1D.
Anticipated Outcome
Our preliminary data showed that the deletion of two genes, Sec24 and Sec31a, made beta (β)-cells more resistant to changes in cell stability and also to the destruction caused by the action of cells from the immune system. Hence, this proposal aims for obtaining a deeper understanding of the role played by SEC24A and SEC31A in the progression of Type 1 Diabetes (T1D). At last, we wish to develop a therapeutic strategy based on the deletion of SEC24A and SEC31A from β-cells. Our experimental approach is initially based on the creation of mutant mouse and human cell lines that have the deletion or overexpression of the above-mentioned genes. These cell lines will be evaluated via a set of experiments focused on two major factors: the response of the mutant cells to i) endoplasmic reticulum (ER) stress and ii) their resistance to attacks from the immune system. Of note, ER is an important cellular structure for regulating cell stability but it may undergo a stress condition and cause improper functioning of the β-cell and exacerbate the action of immune cells. Then, we envisage that the mutant cells devoid of SEC24A and SEC31A will be more resistant to these effects and, in the future, our results will be indispensable for the conception of new strategies to protect β-cells against the development of T1D.
Relevance to T1D
Type 1 diabetes (T1D) is among the major worldwide public health problems, and it was long believed that this condition was solely due to the action of cells of the immune system against pancreatic beta (β)-cells. Under this perspective, β-cells were somewhat considered passive victims of this attack, and little to no perspectives of curing T1D patients existed. With the advance in science, it is now known that pancreatic β-cells may present alterations in their own metabolism that favor immune system attacks. Unfortunately, it is still not possible to cure or prevent T1D, but this change in paradigm about the origin and evolution of the disease has opened new doors and brought fresh perspectives for the development of effective therapies. In this proposal, our goal is to use genetic engineering to protect β-cells from their harmful metabolic alterations that promote recognition and attack by the immune system. In our preliminary studies, we observed that the deletion of two genes, SEC24A and SEC31A, provided promising results in this scenario, which poses an encouraging path toward the development of a therapeutic strategy for the prevention and/or treatment of T1D. In the course of this project, we will combine a diverse set of expertise from our group, including not only genetic engineering, but also immunology, β-cell physiology, and molecular biology, and perform experiments with both mouse diabetic models and human β-cells, to reach an unmet status in T1D therapy.