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Updated: Jun 4, 2025
Modeling and Evaluation of Murine Diabetic Cardiomyopathy Model
Published on: November 29, 2024
DNA repair protein RAD50 is involved in the streptozotocin-induced diabetes susceptibility of mice
Yuki Miyasaka1, Tomoki Maegawa1, Takuma Nagura1
1Division of Experimental Animals, Graduate School of Medicine, Nagoya University, 65 Tsurumai-cho, Showa-ku, Nagoya, Aichi 466-8550, Japan.
Abstract:
Streptozotocin (STZ) is widely used as a pancreatic beta-cell toxin to induce experimental diabetes in rodents. Strain-dependent variations in STZ-induced diabetes susceptibility have been reported in mice. Differences in STZ-induced diabetes susceptibility are putatively related to pancreatic beta-cell fragility via DNA damage response. In this study, we identified two STZ-induced diabetes susceptibility regions in chromosome 11 (Chr11) of Nagoya-Shibata-Yasuda (NSY) mice via congenic mapping using the C3H-11NSY consomic strains, in which the entire Chr11 of STZ-resistant C3H/He (C3H) mice was replaced with that of NSY mice, and named them STZ susceptibility region for NSY (Ssnsy)-1 and -2, respectively. Screening for variants in the Ssnsy1 region revealed that NSY mice exhibited a characteristic missense c.599G>T (p.G200V) variant in a highly conserved region within the DNA repair gene, RAD50 double-strand break repair protein (Rad50). Subsequently, we generated R2B1-Rad50 knock-in mice, in which c.599T in Rad50 of STZ-susceptible C3H.NSY-R2B1 subcongenic mice was replaced with c.599G via genome editing. Compared with C3H.NSY-R2B1 mice, and R2B1-Rad50 knock-in mice showed suppressed hyperglycemia, incidence of diabetes, and decrease in plasma insulin levels following single high-dose and multiple low-dose injections of STZ. Our results suggest Rad50 as a susceptibility gene for STZ-induced diabetes that is involved in pancreatic beta-cell fragility. Forward genetic approaches using inbred mouse strains with STZ susceptibility as a phenotypic indicator will further elucidate the molecular mechanisms of pancreatic beta-cell destruction via DNA damage response.
Insights
This study identifies RAD50 as a key gene influencing susceptibility to streptozotocin-induced diabetes in mice. Genetic modification of RAD50 protected against diabetes, highlighting its role in pancreatic beta-cell fragility.
Area of Science:
- Genetics
- Endocrinology
- Molecular Biology
Background:
- Streptozotocin (STZ) is a widely used diabetogenic agent in rodent models.
- Susceptibility to STZ-induced diabetes varies between mouse strains, linked to pancreatic beta-cell DNA damage response.
- The genetic basis for this differential susceptibility remains incompletely understood.
Purpose of the Study:
- To identify genetic loci associated with STZ-induced diabetes susceptibility in Nagoya-Shibata-Yasuda (NSY) mice.
- To investigate the role of the DNA repair gene RAD50 in STZ-induced pancreatic beta-cell destruction.
Main Methods:
- Congenic mapping using C3H-11NSY consomic mice to identify STZ susceptibility regions on chromosome 11.
- Whole-exome sequencing to screen for variants in candidate genes within identified regions.
- Genome editing to generate RAD50 knock-in mice (R2B1-Rad50) with a specific missense variant correction.
- Assessment of hyperglycemia, diabetes incidence, and plasma insulin levels following STZ administration.
Main Results:
- Two STZ susceptibility regions (Ssnsy-1 and Ssnsy-2) were mapped to chromosome 11 in NSY mice.
- A novel missense variant (c.599G>T, p.G200V) in the DNA repair gene RAD50 was identified in the Ssnsy1 region of NSY mice.
- R2B1-Rad50 knock-in mice exhibited significantly reduced hyperglycemia, lower diabetes incidence, and preserved plasma insulin levels after STZ treatment compared to control mice.
- These findings implicate RAD50 as a critical determinant of STZ-induced diabetes susceptibility.
Conclusions:
- RAD50 acts as a susceptibility gene for STZ-induced diabetes, influencing pancreatic beta-cell fragility through its role in DNA repair.
- Forward genetic approaches in inbred mouse strains can effectively uncover molecular mechanisms underlying complex diseases like diabetes.
- Targeting DNA damage response pathways may offer novel therapeutic strategies for diabetes prevention or treatment.
