Investigating the role of the HNF-1αG319S variant in experimental models reflective of early-onset type 2 diabetes in Anishininew youth
| dc.contributor.author | Morriseau, Taylor | |
| dc.contributor.examiningcommittee | Fernyhough, Paul (Pharmacology and Therapeutics) | en_US |
| dc.contributor.examiningcommittee | Triggs-Raine, Barbara (Biochemistry and Medical Genetics) | en_US |
| dc.contributor.examiningcommittee | Rutter, Guy (Université de Montréal) | en_US |
| dc.contributor.supervisor | Dolinsky, Vernon | |
| dc.contributor.supervisor | Doucette, Christine | |
| dc.date.accessioned | 2023-01-06T17:44:35Z | |
| dc.date.available | 2023-01-06T17:44:35Z | |
| dc.date.copyright | 2022-12-27 | |
| dc.date.issued | 2022-12-27 | |
| dc.date.submitted | 2022-12-27T21:00:52Z | en_US |
| dc.degree.discipline | Pharmacology and Therapeutics | en_US |
| dc.degree.level | Doctor of Philosophy (Ph.D.) | en_US |
| dc.description.abstract | In 1999, candidate gene screening within Anishininew (Oji-Cree) communities uncovered a novel genetic variant in the HNF-1α gene (HNF-1αG319S). Hailed as the strongest genetic predictor of type 2 diabetes (T2D) ever identified, 40% of diagnosed Manitoban youth were also found to be carriers of this variant “S-allele”. The newly discovered G319S variant was believed to drive pancreatic beta-cell dysfunction; however, youth-onset T2D is a relatively recent phenomenon. Therefore, we hypothesized that the G319S variant impairs insulin secretion when exposed to dietary carbohydrate stress but is protective in the context of traditional, off-the-land foods that are rich in fat and protein. To examine this relationship, CRISPR-Cas9 was used to knock-in the G>A.955 substitution into clonal MIN6 beta-like cells (“G319S-MIN6”) and into a C57BL/6N mouse background generating two novel experimental models. Mice were weaned onto (1) standard grain-based chow, (2) a high-fat, low-carbohydrate (HFLC) diet modelled after traditional, off-the-land foods, or (3) a high-fat, high-carbohydrate (HFHC) diet reflecting present-day Western dietary patterns. In vitro, we assessed gene expression, insulin secretion dynamics, and oxidative respiration under different macronutrient exposures. In vivo, we completed a comprehensive characterization of both male and female mice between 3- and 6-months-of-age terminating with islet isolation to assess insulin secretion and gene expression by single-cell RNA sequencing. In support of our hypothesis, the short-term consumption of a HFLC diet appears to normalize insulin secretion and glucose tolerance whereas a HFHC diet accelerates cardiometabolic dysfunction and impairs insulin secretion in G319S-expressing mice. In G319S-MIN6 cells or islets, fatty acid oxidation was increased, and gene expression changes supported a metabolic switch away from glucose respiration. Importantly, these findings demonstrate that genetics alone cannot explain T2D onset in G319S-carriers, rather gene-diet interactions, particularly a Westernized diet containing simple carbohydrates and saturated fats, leads to distinct metabolic outcomes that impact short- and long-term health. These studies may inform nutritional interventions for youth with T2D while ultimately supporting community-led efforts to access off-the-land traditional foods. | en_US |
| dc.description.note | February 2023 | en_US |
| dc.description.sponsorship | Prairie Indigenous Knowledge Exchange Network (PIKE-Net) Graduate Fellowship | en_US |
| dc.identifier.uri | http://hdl.handle.net/1993/37063 | |
| dc.language.iso | eng | en_US |
| dc.rights | open access | en_US |
| dc.subject | Islet biology | en_US |
| dc.subject | Indigenous health | en_US |
| dc.subject | Genetics | en_US |
| dc.subject | Nutrition | en_US |
| dc.subject | Type 2 diabetes | en_US |
| dc.title | Investigating the role of the HNF-1αG319S variant in experimental models reflective of early-onset type 2 diabetes in Anishininew youth | en_US |
| dc.type | doctoral thesis | en_US |
| local.subject.manitoba | yes | en_US |
| oaire.awardNumber | 395907 | en_US |
| oaire.awardTitle | Vanier Canada Graduate Scholarship | en_US |
| oaire.awardURI | https://vanier.gc.ca/en/home-accueil.html | en_US |
| project.funder.identifier | https://doi.org/10.13039/501100000024 | en_US |
| project.funder.name | Canadian Institutes of Health Research | en_US |