Limits...
A novel cellular defect in diabetes: membrane repair failure.

Howard AC, McNeil AK, Xiong F, Xiong WC, McNeil PL - Diabetes (2011)

Bottom Line: Skeletal muscle myopathy is a common diabetes complication.Downhill running also resulted in a higher level of repair failure in diabetic mice.However, a repair defect could be induced, in the absence of high glucose, by enhancing AGE binding to RAGE, or simply by increasing cell exposure to AGE.

View Article: PubMed Central - PubMed

Affiliation: Institute of Molecular Medicine and Genetics, Georgia Health Sciences University, Augusta, Georgia, USA.

ABSTRACT

Objective: Skeletal muscle myopathy is a common diabetes complication. One possible cause of myopathy is myocyte failure to repair contraction-generated plasma membrane injuries. Here, we test the hypothesis that diabetes induces a repair defect in skeletal muscle myocytes.

Research design and methods: Myocytes in intact muscle from type 1 (INS2(Akita+/-)) and type 2 (db/db) diabetic mice were injured with a laser and dye uptake imaged confocally to test repair efficiency. Membrane repair defects were also assessed in diabetic mice after downhill running, which induces myocyte plasma membrane disruption injuries in vivo. A cell culture model was used to investigate the role of advanced glycation end products (AGEs) and the receptor for AGE (RAGE) in development of this repair defect.

Results: Diabetic myocytes displayed significantly more dye influx after laser injury than controls, indicating a repair deficiency. Downhill running also resulted in a higher level of repair failure in diabetic mice. This repair defect was mimicked in cultured cells by prolonged exposure to high glucose. Inhibition of the formation of AGE eliminated this glucose-induced repair defect. However, a repair defect could be induced, in the absence of high glucose, by enhancing AGE binding to RAGE, or simply by increasing cell exposure to AGE.

Conclusions: Because one consequence of repair failure is rapid cell death (via necrosis), our demonstration that repair fails in diabetes suggests a new mechanism by which myopathy develops in diabetes.

Show MeSH

Related in: MedlinePlus

High glucose treatment also results in failure to repair mechanically induced disruptions. C2C12 myoblasts were cultured for 2 or 8 weeks in 7.5 mmol/L glucose (N Gluc), 30 mmol/L glucose (H Gluc), or iso-osmolar control 30 mmol/L mannitol (Man) and then scraped from 96-well plates. A live/dead or MTT assay was then performed to assess cell survival. No significant differences were demonstrated after 2 weeks of treatment. However, 8 weeks of high glucose treatment decreased survival as determined by both assays. Data are presented as the mean ± SEM. *P < 0.01; n = 24 wells for each condition.
© Copyright Policy - creative-commons
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC3198060&req=5

Figure 4: High glucose treatment also results in failure to repair mechanically induced disruptions. C2C12 myoblasts were cultured for 2 or 8 weeks in 7.5 mmol/L glucose (N Gluc), 30 mmol/L glucose (H Gluc), or iso-osmolar control 30 mmol/L mannitol (Man) and then scraped from 96-well plates. A live/dead or MTT assay was then performed to assess cell survival. No significant differences were demonstrated after 2 weeks of treatment. However, 8 weeks of high glucose treatment decreased survival as determined by both assays. Data are presented as the mean ± SEM. *P < 0.01; n = 24 wells for each condition.

Mentions: To confirm that this glucose-induced repair defect was not limited to laser-generated disruptions, adherent C2C12 cells were scraped to mechanically induce membrane disruptions (23). Survival was then assessed using two independent assays: live/dead and MTT. Consistent with the laser assay, there was no detectable difference in survival between treatment groups after 2 weeks of high glucose exposure (Fig. 4, 2 weeks). However, after 8 weeks of elevated glucose, cells displayed a significant decrease in survival when compared with those grown in normal glucose or mannitol (Fig. 4, 8 weeks H Gluc). Thus, using an independent method for inducing membrane disruptions and for monitoring repair failure, we confirmed that high glucose leads to the development of a membrane repair defect.


A novel cellular defect in diabetes: membrane repair failure.

Howard AC, McNeil AK, Xiong F, Xiong WC, McNeil PL - Diabetes (2011)

High glucose treatment also results in failure to repair mechanically induced disruptions. C2C12 myoblasts were cultured for 2 or 8 weeks in 7.5 mmol/L glucose (N Gluc), 30 mmol/L glucose (H Gluc), or iso-osmolar control 30 mmol/L mannitol (Man) and then scraped from 96-well plates. A live/dead or MTT assay was then performed to assess cell survival. No significant differences were demonstrated after 2 weeks of treatment. However, 8 weeks of high glucose treatment decreased survival as determined by both assays. Data are presented as the mean ± SEM. *P < 0.01; n = 24 wells for each condition.
© Copyright Policy - creative-commons
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3198060&req=5

Figure 4: High glucose treatment also results in failure to repair mechanically induced disruptions. C2C12 myoblasts were cultured for 2 or 8 weeks in 7.5 mmol/L glucose (N Gluc), 30 mmol/L glucose (H Gluc), or iso-osmolar control 30 mmol/L mannitol (Man) and then scraped from 96-well plates. A live/dead or MTT assay was then performed to assess cell survival. No significant differences were demonstrated after 2 weeks of treatment. However, 8 weeks of high glucose treatment decreased survival as determined by both assays. Data are presented as the mean ± SEM. *P < 0.01; n = 24 wells for each condition.
Mentions: To confirm that this glucose-induced repair defect was not limited to laser-generated disruptions, adherent C2C12 cells were scraped to mechanically induce membrane disruptions (23). Survival was then assessed using two independent assays: live/dead and MTT. Consistent with the laser assay, there was no detectable difference in survival between treatment groups after 2 weeks of high glucose exposure (Fig. 4, 2 weeks). However, after 8 weeks of elevated glucose, cells displayed a significant decrease in survival when compared with those grown in normal glucose or mannitol (Fig. 4, 8 weeks H Gluc). Thus, using an independent method for inducing membrane disruptions and for monitoring repair failure, we confirmed that high glucose leads to the development of a membrane repair defect.

Bottom Line: Skeletal muscle myopathy is a common diabetes complication.Downhill running also resulted in a higher level of repair failure in diabetic mice.However, a repair defect could be induced, in the absence of high glucose, by enhancing AGE binding to RAGE, or simply by increasing cell exposure to AGE.

View Article: PubMed Central - PubMed

Affiliation: Institute of Molecular Medicine and Genetics, Georgia Health Sciences University, Augusta, Georgia, USA.

ABSTRACT

Objective: Skeletal muscle myopathy is a common diabetes complication. One possible cause of myopathy is myocyte failure to repair contraction-generated plasma membrane injuries. Here, we test the hypothesis that diabetes induces a repair defect in skeletal muscle myocytes.

Research design and methods: Myocytes in intact muscle from type 1 (INS2(Akita+/-)) and type 2 (db/db) diabetic mice were injured with a laser and dye uptake imaged confocally to test repair efficiency. Membrane repair defects were also assessed in diabetic mice after downhill running, which induces myocyte plasma membrane disruption injuries in vivo. A cell culture model was used to investigate the role of advanced glycation end products (AGEs) and the receptor for AGE (RAGE) in development of this repair defect.

Results: Diabetic myocytes displayed significantly more dye influx after laser injury than controls, indicating a repair deficiency. Downhill running also resulted in a higher level of repair failure in diabetic mice. This repair defect was mimicked in cultured cells by prolonged exposure to high glucose. Inhibition of the formation of AGE eliminated this glucose-induced repair defect. However, a repair defect could be induced, in the absence of high glucose, by enhancing AGE binding to RAGE, or simply by increasing cell exposure to AGE.

Conclusions: Because one consequence of repair failure is rapid cell death (via necrosis), our demonstration that repair fails in diabetes suggests a new mechanism by which myopathy develops in diabetes.

Show MeSH
Related in: MedlinePlus