Characterization of pancreatic beta cell fate in murine models of MODY3 (experimental application)
Purpose: to characterise the cellular and molecular basis of the gradual failure of insulin-producing beta-cells in HNF1a mutation leading to monogenic diabetes MODY3 (Maturity Onset Diabetes of the Young) human patients. To achieve this, we generated two mouse models of human HNF1a mutation, direct counterparts of MODY3 patients. These murine models express both the wild-type and mutant allele at endogenous levels under the control of the endogenous regulatory elements, thus excluding deleterious manifestations due to transgene overexpression. Importantly, the mutation is activated only upon conditional induction (mice will be normal and healthy before induction), allowing a tight selection of the cell-type affected and/or time of induction.
Expected distress for the animals: we plan to use mild procedures here. Moreover, as in our mice models the mutation activation is conditional, we are able to tightly monitor the disease onset and consequently decide early pre-clinical humane endpoints (physiological). Unless the animals are treated with insulin as we already carefully planned (see Protocols) they might develop, similar to diabetic patients, different degrees of diabetes symptoms: polyuria, hyperphagia, polydipsia, cachexia and even death (weeks/months following first symptoms). To prevent these, we will regularly monitor, as in humans, the physiological status (like glycaemia, weight) of the animals and treat them with insulin upon registered prolonged hyperglycaemia (max. 10 days) and always before severe distress (Thorel et al. Nature 2010; Chera et al. Nature 2014, Ghila et al., Nature Cell Biol. 2018, Furuyama et al., Nature 2019).
Expected scientific or societal benefit: As the prevalent forms of diabetes are complex disorders, it remains largely unknown what are the cellular and molecular basis of insulin-producing beta-cell decay. Identifying these processes is a pre-requirement for understanding diabetes onset. The study of other complex disorders, such as Parkinson, strongly benefited from researching their monogenic variants. Our projects aim at characterizing the unknown mechanisms governing the decay of beta-cells in monogenic diabetes. This study will provide the first comprehensive cellular and molecular timeline of beta-cell decay as well as systematically define the beta-cell niche in diabetes. As only a limited number of scenarios can be considered for stress-related cell-fate changes, the revealed process of beta-cell failure will be relevant for the complex forms of diabetes. Moreover, our transcriptomic analyses will uncover new potential therapeutic targets. Our findings will allow a more efficient clinical intervention with a greater gain in terms of functionality and health span for patients, especially considering the gender-related effect that we observed in our preliminary experiments.
Animals to be used: transgenic mice.
Replacement, reduction and improvement: All experiments that do not require a living organism (metabolism; systemic organ interactions) are performed in vitro by using patient-derived hiPSC. However, as diabetes is a systemic disease involving several organs, certain in vivo studies are unavoidable. Nevertheless, we will optimize the number of mice necessary for our 2 projects by using common experimental groups, where possible to have the same set of collected samples processed separately for replying distinct questions, hence reducing the number of required animals.
Expected distress for the animals: we plan to use mild procedures here. Moreover, as in our mice models the mutation activation is conditional, we are able to tightly monitor the disease onset and consequently decide early pre-clinical humane endpoints (physiological). Unless the animals are treated with insulin as we already carefully planned (see Protocols) they might develop, similar to diabetic patients, different degrees of diabetes symptoms: polyuria, hyperphagia, polydipsia, cachexia and even death (weeks/months following first symptoms). To prevent these, we will regularly monitor, as in humans, the physiological status (like glycaemia, weight) of the animals and treat them with insulin upon registered prolonged hyperglycaemia (max. 10 days) and always before severe distress (Thorel et al. Nature 2010; Chera et al. Nature 2014, Ghila et al., Nature Cell Biol. 2018, Furuyama et al., Nature 2019).
Expected scientific or societal benefit: As the prevalent forms of diabetes are complex disorders, it remains largely unknown what are the cellular and molecular basis of insulin-producing beta-cell decay. Identifying these processes is a pre-requirement for understanding diabetes onset. The study of other complex disorders, such as Parkinson, strongly benefited from researching their monogenic variants. Our projects aim at characterizing the unknown mechanisms governing the decay of beta-cells in monogenic diabetes. This study will provide the first comprehensive cellular and molecular timeline of beta-cell decay as well as systematically define the beta-cell niche in diabetes. As only a limited number of scenarios can be considered for stress-related cell-fate changes, the revealed process of beta-cell failure will be relevant for the complex forms of diabetes. Moreover, our transcriptomic analyses will uncover new potential therapeutic targets. Our findings will allow a more efficient clinical intervention with a greater gain in terms of functionality and health span for patients, especially considering the gender-related effect that we observed in our preliminary experiments.
Animals to be used: transgenic mice.
Replacement, reduction and improvement: All experiments that do not require a living organism (metabolism; systemic organ interactions) are performed in vitro by using patient-derived hiPSC. However, as diabetes is a systemic disease involving several organs, certain in vivo studies are unavoidable. Nevertheless, we will optimize the number of mice necessary for our 2 projects by using common experimental groups, where possible to have the same set of collected samples processed separately for replying distinct questions, hence reducing the number of required animals.