Collagen-Induced Arthritis Analysis in Rhbdf2 Knockout Mouse

Rhomboid family member 2 gene (Rhbdf2) is an inactive homologue lacking essential catalytic residues of rhomboid intramembrane serine proteases. The protein is necessary for maturation of tumor necrosis factor-alpha (TNF-α) converting enzyme, which is the molecule responsible for the release of TNF-α. In this study, Rhbdf2 knockout (KO) mice were produced by CRISPR/CAS9. To see the effects of the failure of TNF-α release induced by Rhbdf2 gene KO, collagen-induced arthritis (CIA), which is the representative TNF-α related disease, was induced in the Rhbdf2 mutant mouse using chicken collagen type II. The severity of the CIA was measured by traditional clinical scores and histopathological analysis of hind limb joints. A rota-rod test and grip strength test were employed to evaluate the severity of CIA based on losses of physical functions. The results indicated that Rhbdf2 mutant mice showed clear alleviation of the clinical severity of CIA as demonstrated by the significantly lower severity indexes. Moreover, a grip strength test was shown to be useful for the evaluation of physical functional losses by CIA. Overall, the results showed that the Rhbdf2 gene has a significant effect on the induction of CIA, which is related to TNF-α.

An age-dependent alteration of the respiratory exchange ratio in the db/db mouse / 한국실험동물학회지

The leptin receptor-deficient db/db mouse is a rodent model of type 2 diabetes and obesity. Diabetes in db/db mice shows an age-dependent progression, with early insulin resistance followed by an insulin secretory defect resulting in profound hyperglycemia. However, there is insufficient data on agedependent changes of energy metabolism in db/db mice. We demonstrated an age-dependent decrease in the respiratory exchange ratio (RER), calculated by a ratio of VO2/VCO2, in db/db mice. The RER determined by indirect calorimetry, was 1.03 in db/db mice under 6 weeks of age, which were similar to those in heterozygote (db/+) and wild-type (+/+) mice. However, RER decreased from approximately 0.9 to 0.8 by 10 weeks of age and subsequently returned to approximately 0.9 at 22 weeks of age. The changes in RER were concurrent with the alterations in body weight and blood glucose level. However, other metabolic indicators such as glucose tolerance, changes in body fat mass, and urinary glucose levels, did not change with age. The results suggested that the energy source utilized in db/db mice changed with the age-related progression of diabetes.

Effect of N-ethyl-N-nitrosourea on the fatality, recovery of fertile period and breeding record in C57BL/6J mice / 동물의과학연구지

N-ethyl-N-nitrosourea (ENU) is a potent mutagen in a mouse model by inducing point mutation in a random manner and, in particular, causing heritable base substitutions in spermatogonia. In this study, systematic development of phenotype-driven mutant mice with large scale was carried out by using ENU. Nine-week-old male mice of C57BL/6J received intraperitoneal injection at three times with 100 mg/kg of ENU at weekly intervals for three weeks. After injections with ENU, the changes of body weight, fatality, recovery of fertile period, and breeding record were measured in these mice. Body weight lost as a result of ENU treatments was reversed after the last ENU injection. Live fertile male mice recovered from infertility from 104 to 165 days after ENU treatments were mated with C57BL/6J female mice for generation of G1 offspring. An average birth rate was 5.9 mice from 1 pair of paternal and maternal mice. All of 231 G1 offspring mice were analyzed by modified-SHIRPA with standard procedure at nine weeks of age. Among G1 mice, 166 mice were identified as mutagenic phenotypes in 20 test items. The changes in mutagenic phenotypes after ENU treatments, for instance, pattern in the region with a different color, touch escape, changes in head morphology, pupil, and teeth, and negative geotaxis etc., were found in these mice. Taken together, these results indicate that ENU may be a trans-generational mutagen in C57BL/6J mice.