Abstract

Diabetes is a group of diseases characterized by chronic hyperglycemia triggered by the inability of the body to produce and/or use sufficient insulin. It occurs when pancreatic insulin-producing β-cells fail to meet the insulin demand due to destruction or dysfunction. An important cause of β-cell loss is apoptosis triggered by terminal endoplasmic reticulum (ER) stress characterizing severely overworked β-cells. This depletion generates increasing stress on the remaining β-cells, impairing their function. Despite major advances, self-management of diabetes remains an unremitting challenge. Therefore, there is an imperious need for the development of a reliable curative therapy implying a robust glucose control limiting the necessity of constant interventions. For both type 1 and type 2 diabetes, an important therapeutic goal is to develop novel β-cell regeneration strategies. To respond to this considerable need, BETAUPREG project proposes to design, refine and consolidate a clinically relevant therapeutic approach aimed at restoring β-cell function in the diabetic pancreas by modulating the unfolded protein response (UPR). This is particularly promising therapeutic target as the ER of β-cells, “professional secretory cells”, manages a tremendous amount of proteins, eliciting a strong pressure on the ER intrinsic folding capacity. Of note, UPR is a conserved mechanism, which helps the secretory performance of a cell by improving its capacity to cope with increased ER load. Our proposed novel strategy is aimed at promoting the β-cells’ secretory function by ameliorating their capacity to cope with increased ER load. We aim to induce a mild or adaptive UPR that would prepare and prime the β-cell for a more efficient protein processing, granting stress resistance and inherently restoring homeostatic glucose levels control. We are certain that our results we will prove instrumental in better designing, refining and consolidating therapeutic interventions that target UPR modulation in diabetes and will be inspirational for other chronic disorders with an ER stress component. 

Objective

The scientific objective of BETAUPREG project was to design, refine and consolidate a clinically relevant therapeutic approach to regenerate β cell function of the diabetic pancreas by modulating a fundamental cellular process, the unfolded protein response (UPR). This was achieved through the following aims: a. Identifying and characterizing the early secretory pathway disturbances that occur during diabetes progression of different models in conjunction with varied insults; b. Defining UPR subclasses that occur in β cells during diabetes progression for different diabetes models; c. Modulating UPR in different diabetes models in order to restore insulin homeostasis.

Results

1. Subcellular characterization of the early secretory pathway of the β-cells during progression of diabetes, or through various stressful conditions.

This was imperative because it deepened the understanding of the β-cell stress response, how it handled this stress, and how it adapted. By identifying the timing of the structural modifications that occur in these cells, and following them after the various interventions aimed to aggravate, or to alleviate the stress, allows to better define the potential therapeutic interventions.

2. In depth molecular characterization of the islet response to either (1) early insulitis during diabetes onset in the NOD mice, or (2) mild ablation in the RIP-DTR 50% system, in the absence or presence of additional insults.

This was of crucial importance for identifying key factors responsible for decreased proliferation, increased stress, enhanced regeneration that can be targeted in an attempt to support or recover the necessary β-cell mass for insulin requirements.

3. Enhanced understanding of β-cell functional heterogeneity.

Significant strides have been made in mapping out the varied responses of β-cells to different stressors. By identifying diverse β-cell populations and their unique reactions to environments like increased inflammation (in the NOD mice), high-fat diet, increased glucose exposure, or chemical stressors, our project has provided valuable insights into cellular mechanisms that could be targeted for therapeutic intervention.

4. Characterization of the β-cell response upon activation of the UPR branch, Atf6, through AA147.

By identifying the mechanisms underlying this response, we underline the importance of UPR in β-cell homeostasis.

5. Systematic characterization of the UPR response of differentiated 3D islets organoids from human induced pluripotent stem cells exposed to various stressors.

Importance: These insights are crucial as they lay the groundwork for potential therapeutic targets and strategies to enhance β-cell resilience and function. For example, the identification of different β-cell populations and their responses to various stressors like high-fat diets helps in tailoring more precise therapeutic approaches.

Project registration code: RO-NO-2019-0544 

Budget: €1,163,385.20

Project implementation period: October 2020 - March 2024

Project financed by Norway Grants 2014-2021 and operated by UEFISCDI.