Related Experiment Videos
Diabetes interferes with the bone formation by affecting the expression of transcription factors that regulate
Huafei Lu1, Douglas Kraut, Louis C Gerstenfeld
1Department of Periodontology and Oral Biology, Boston University School of Dental Medicine, Boston, Massachusetts 02118, USA.
Abstract:
Type 1 diabetes in humans has as one of its complications inadequate bone formation, resulting in osteopenia and delayed fracture healing. To investigate the mechanisms by which diabetes affects bone formation, experiments were performed in a marrow ablation model. Mice were made diabetic by multiple low-dose streptozotocin treatment, and controls were treated with vehicle alone. Killing occurred 0, 2, 4, 6, 10, and 16 d following marrow ablation. Histologic analysis demonstrated that the amount of immature mesenchymal tissue was equivalent in both the experimental and control groups on d 4. On d 6 a burst of bone formation occurred in the control group that was significantly reduced in the diabetic group. This deficit was evident at the molecular level as shown by diminished expression of osteocalcin, collagen types I. When transcription factors were examined, core-binding factor alpha1 (Cbfa1)/runt domain factor-2 (Runx-2) and human homolog of the drosophila distal-less gene (Dlx5) expression were substantially reduced in the diabetic, compared with control, groups on d 4 and 6. C-fos but not c-jun expression was also suppressed in the diabetic group but not closely linked to bone formation. Insulin treatment substantially reversed the effect of diabetes on the expression of bone matrix osteocalcin and collagen type I and transcription factors Cbfa1/Runx2 and Dlx5. These results indicate that diabetic animals produce sufficient amounts of immature mesenchymal tissue but fail to adequately express genes that regulate osteoblast differentiation, Cbfa1/Runx-2 and Dlx5, which in turn, leads to decreased bone formation.
Insights
Type 1 diabetes impairs bone formation by reducing key gene expression in osteoblasts, leading to osteopenia. Insulin therapy can reverse these effects, improving bone health in diabetic models.
Area of Science:
- Endocrinology and Metabolism
- Bone Biology and Osteoporosis Research
Background:
- Type 1 diabetes is linked to bone complications like osteopenia and delayed fracture healing.
- The precise mechanisms by which diabetes negatively impacts bone formation remain incompletely understood.
Purpose of the Study:
- To investigate the molecular mechanisms underlying impaired bone formation in a mouse model of type 1 diabetes.
- To assess the role of specific transcription factors and bone matrix proteins in diabetic bone disease.
Main Methods:
- Mice were induced into diabetes using streptozotocin and subjected to a marrow ablation model.
- Bone formation was analyzed histologically and at the molecular level (gene expression) at multiple time points post-ablation.
- The effect of insulin treatment on gene expression and bone formation was evaluated.
Main Results:
- Diabetic mice showed significantly reduced bone formation compared to controls, particularly on day 6 post-ablation.
- Expression of osteocalcin, collagen type I, and transcription factors core-binding factor alpha1 (Cbfa1)/runt domain factor-2 (Runx-2) and Dlx5 were substantially decreased in diabetic mice.
- Insulin treatment effectively restored the expression of these bone-related genes.
Conclusions:
- Diabetes leads to inadequate expression of genes crucial for osteoblast differentiation (Cbfa1/Runx-2, Dlx5), despite sufficient immature mesenchymal tissue.
- This molecular deficit directly contributes to decreased bone formation and associated complications in diabetes.
- Targeting these molecular pathways, potentially with insulin, may offer therapeutic strategies for diabetic bone disease.