Improving â-cell function by drug treatment

1 Purpose: Previously we developed a mouse model of monogenic diabetes, carrying HNF1a inducible mutation, which showed a gradual accumulation of somatostatin cell numbers, leading to hyperglycemia and thus, diabetes onset (experiments performed under FOTS 10785 and 12015). By following our experimental mice we also observed a difference in hyperglycemia level due to changes in islet cell populations. This project aims at determining the disease mechanism induced by lack of HNF1a (our monogenic diabetes model) by treating the mice with insulin modulators, such as S961, FoxO1 inhibitor, and wortmanin. Also the role of other endocrine cell populations (glucagon- and somatostatin-producing cells) will be investigated aiming at find novel ways to lower blood glycemia.

2 Distress: We identified as sources of distress:
(1) mild hyperglycemia due to HNF1a mutation (not requiring insulin treatment)
(2) regular (i.p.) injections administering FoxO1 inhibitor, wortmanin and diphtheria toxin. All these compounds were used before in mouse experiments and no additional discomfort was associated with their use. Contrary, we expect to improve the glycemic status and metabolic state of the treated mice.

3 Expected benefit: Monogenic diabetes like MODY (maturity onset of diabetes of the young) shows a high variability related to the age of the disease onset. This may be correlated with the gradual accumulation of other cell endocrine types, and a simultaneous decrease in insulin-producing cells. Identifying ways to keep insulin-producing cells healthy and functional by pill treatment would greatly benefit people carrying the disease mutation but not yet exhibiting the disease signs. Our previous studies showed a significant difference on severely diabetic mice treated with S961 or FoxO1 inhibitor. However, those studies did not cover the effect on mildly hyperglycemia models, such as MODY3.

4 Number of animals, and what kind: We will use transgenic mice with inducible mutation in HNF1a (floxed) or HNF1a (humanized), under the control of RIPcre or Ngn3cre, specific promoters that lead to the selective expression of the mutation only in insulin producing cells. These mice are also carrying florescent reporter transgenes (GluVenus and RIPmCherry), which will label the cells carrying the mutated protein.

5 How to adhere to 3R: These experiments require a living organism due to its target on systemic metabolism, studying several organs’ interactions. We will optimize the number of mice necessary for our projects by using common experimental groups, where the same set of collected samples will be processed separately for replying to distinct questions, hence halving the number of required animals. For establishing the experimental setups we screened the literature in order to establish a proven protocol, thus eliminating the need to pretesting the experimental conditions. All protocols proposed here are already in use by our research group having extensive experience in their execution.