Related Experiment Videos
Expression of the glucose transporter GLUT4 in the muscular dystrophic mdx mouse
C Olichon-Berthe1, N Gautier, E Van Obberghen
1INSERM U 145, Faculté de Médecine, Nice, France.
Abstract:
Glucose transporter protein levels have been investigated in mdx and control (C57Bl/10) mice. Crude membrane fractions (microsomes plus plasma membranes) were prepared from skeletal muscle, heart, diaphragm and brain of 5-6-week-old and 6-7-month-old control and mdx mice. Using Western blot analysis with C-terminal-specific anti-peptide antibodies, we investigated the glucose transporters GLUT4 in the different muscle tissues and GLUT1 in brain. In skeletal tissue from the hindlegs, GLUT4 was increased by approximately 55% in mdx mice compared with control mice at both ages studied. In the diaphragm, the amount of GLUT4 protein was unchanged in young mdx mice, and was decreased by 37.4 +/- 4.7% in older mice compared with age-matched control mice. No difference was observed between mdx and control mice in the amounts of GLUT4 and GLUT1 in heart and brain preparations respectively. To determine whether the change in GLUT4 protein observed in the diaphragm and skeletal muscle of mdx mice was regulated through changes at the level of glucose transporter mRNA, Northern blot analyses were performed. In skeletal muscle, GLUT4 mRNA level per tissue was not different between the two groups of mice at both ages studied. In contrast, the decrease in the amount of GLUT4 protein observed in the diaphragm of 6-7-month-old mdx mice was accompanied by a decrease in the GLUT4 mRNA level. In conclusion, the levels of GLUT4 protein were modified in muscle tissues from mdx compared with control mice, and these modifications were different depending on the muscle involved and the age of the mice. An increase in the amount of GLUT4 protein in the skeletal muscle of mdx mice was not due to changes at the mRNA level. The diaphragms of 6-7-month-old mdx mice exhibited decreases in GLUT4 protein and mRNA levels that were not detected in young animals (5-6 weeks old).
Insights
Glucose transporter protein levels, specifically GLUT4, are altered in mdx mice muscles. Skeletal muscle shows increased GLUT4, while diaphragm GLUT4 decreases with age, independent of mRNA levels in skeletal muscle.
Area of Science:
- Biochemistry
- Molecular Biology
- Physiology
Background:
- Glucose transporters are crucial for cellular energy metabolism.
- Duchenne muscular dystrophy (DMD) is characterized by progressive muscle degeneration.
- Investigating glucose transporter alterations in DMD models can reveal metabolic dysfunctions.
Purpose of the Study:
- To quantify glucose transporter protein and mRNA levels in various tissues of mdx mice, a model for DMD.
- To compare these levels with age-matched control mice (C57Bl/10).
- To elucidate the regulatory mechanisms of glucose transporter expression in DMD.
Main Methods:
- Western blot analysis was used to measure glucose transporter protein levels (GLUT4 in muscle, GLUT1 in brain).
- Northern blot analysis was performed to assess glucose transporter mRNA levels.
- Tissues analyzed included skeletal muscle, heart, diaphragm, and brain from young and adult mice.
Main Results:
- Skeletal muscle (hindlegs) showed a ~55% increase in GLUT4 protein in mdx mice at both ages, without changes in GLUT4 mRNA.
- Diaphragm GLUT4 protein was unchanged in young mdx mice but decreased by ~37% in older mdx mice, accompanied by reduced GLUT4 mRNA.
- No significant differences in GLUT4 or GLUT1 protein were found in heart or brain, respectively.
Conclusions:
- GLUT4 protein levels are differentially affected in mdx mouse muscles based on tissue type and age.
- Increased skeletal muscle GLUT4 in mdx mice is not regulated at the mRNA level.
- Diaphragm GLUT4 downregulation in older mdx mice involves both protein and mRNA level changes, suggesting age-dependent metabolic adaptations.