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miR-146a-Mediated extracellular matrix protein production in chronic diabetes complications.

Feng B, Chen S, McArthur K, Wu Y, Sen S, Ding Q, Feldman RD, Chakrabarti S - Diabetes (2011)

Bottom Line: Cardiac and renal tissues were analyzed from type 1 and type 2 diabetic animals.Additional experiments showed that p300 regulates miR-146a.Similar changes were seen in the retinas, kidneys, and hearts in type 1 and type 2 diabetic animals.

View Article: PubMed Central - PubMed

Affiliation: Department of Pathology, Schulich School of Medicine and Dentistry and the University of Western Ontario, London, Ontario, Canada.

ABSTRACT

Objective: MicroRNAs (miRNAs), through transcriptional regulation, modulate several cellular processes. In diabetes, increased extracellular matrix protein fibronectin (FN) production is known to occur through histone acetylator p300. Here, we investigated the role of miR-146a, an FN-targeting miRNA, on FN production in diabetes and its relationship with p300.

Research design and methods: miR-146a expressions were measured in endothelial cells from large vessels and retinal microvessels in various glucose levels. FN messenger RNA expression and protein levels with or without miR-146a mimic or antagomir transfection were examined. A luciferase assay was performed to detect miR-146a's binding to FN 3'-untranslated region (UTR). Likewise, retinas from type 1 diabetic rats were studied with or without an intravitreal injection of miR-146a mimic. In situ hybridization was used to localize retinal miR-146a. Cardiac and renal tissues were analyzed from type 1 and type 2 diabetic animals.

Results: A total of 25 mmol/L glucose decreased miR-146a expression and increased FN expression compared with 5 mmol/L glucose in both cell types. miR-146a mimic transfection prevented such change, whereas miR-146a antagomir transfection in the cells in 5 mmol/L glucose caused FN upregulation. A luciferase assay confirmed miR-146a's binding to FN 3'-UTR. miR-146a was localized in the retinal endothelial cells and was decreased in diabetes. Intravitreal miR-146a mimic injection restored retinal miR-146a and decreased FN in diabetes. Additional experiments showed that p300 regulates miR-146a. Similar changes were seen in the retinas, kidneys, and hearts in type 1 and type 2 diabetic animals.

Conclusions: These studies showed a novel, glucose-induced molecular mechanism in which miR-146a participates in the transcriptional circuitry regulating extracellular matrix protein production in diabetes.

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Related in: MedlinePlus

In the retina (upper row), heart (middle row), and kidneys (lower row) of type 2 diabetic (db/db) mice, miR-146a levels were reduced (A–C) and FN mRNA (D–F) and p300 mRNA (G–I) levels were elevated after 2 months of poorly controlled diabetes (db). *Significantly different from control (Co), miRNA levels are expressed as a ratio of RNU6B (U6) normalized to control; mRNA levels are expressed as a ratio to β-actin normalized to control.
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Figure 6: In the retina (upper row), heart (middle row), and kidneys (lower row) of type 2 diabetic (db/db) mice, miR-146a levels were reduced (A–C) and FN mRNA (D–F) and p300 mRNA (G–I) levels were elevated after 2 months of poorly controlled diabetes (db). *Significantly different from control (Co), miRNA levels are expressed as a ratio of RNU6B (U6) normalized to control; mRNA levels are expressed as a ratio to β-actin normalized to control.

Mentions: We then asked the question whether the changes we saw are retina specific or are present in other organs, such as kidney and heart, which also are affected by chronic diabetes complications. To this extent, we investigated FN and p300 mRNA expression analysis and performed miR-146a analyses from the cardiac and renal tissues of STZ-induced diabetic rats. Poorly controlled diabetes for 1 month cause augmented FN and p300 mRNA expression in association with reduced miR-146a levels in the kidney and heart (Fig. 5A–F). To further examine whether such changes occur also in type 2 diabetes, we examined retinal, renal, and cardiac tissues from db/db mice after 2 months of poorly controlled diabetes. At this time point, these animals developed several changes characteristic of chronic diabetes complications (20,28). Db/db mice demonstrated hyperglycemia (serum glucose; diabetes 29.1 ± 2.5 mmol/L and controls 8.9 ± 2.7 mmol/L, P < 0.05) and increased body weight (diabetes 44.4 ± 2.5 g and controls 34 ± 2.5 g, P < 0.05) compared with controls. Similar to the type 1 diabetes model, diabetic db/db mice showed augmented FN and p300 mRNA expression in the retina, kidney, and heart in association with reduced miR-146a levels (Fig. 6A–I).


miR-146a-Mediated extracellular matrix protein production in chronic diabetes complications.

Feng B, Chen S, McArthur K, Wu Y, Sen S, Ding Q, Feldman RD, Chakrabarti S - Diabetes (2011)

In the retina (upper row), heart (middle row), and kidneys (lower row) of type 2 diabetic (db/db) mice, miR-146a levels were reduced (A–C) and FN mRNA (D–F) and p300 mRNA (G–I) levels were elevated after 2 months of poorly controlled diabetes (db). *Significantly different from control (Co), miRNA levels are expressed as a ratio of RNU6B (U6) normalized to control; mRNA levels are expressed as a ratio to β-actin normalized to control.
© Copyright Policy - creative-commons
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3198068&req=5

Figure 6: In the retina (upper row), heart (middle row), and kidneys (lower row) of type 2 diabetic (db/db) mice, miR-146a levels were reduced (A–C) and FN mRNA (D–F) and p300 mRNA (G–I) levels were elevated after 2 months of poorly controlled diabetes (db). *Significantly different from control (Co), miRNA levels are expressed as a ratio of RNU6B (U6) normalized to control; mRNA levels are expressed as a ratio to β-actin normalized to control.
Mentions: We then asked the question whether the changes we saw are retina specific or are present in other organs, such as kidney and heart, which also are affected by chronic diabetes complications. To this extent, we investigated FN and p300 mRNA expression analysis and performed miR-146a analyses from the cardiac and renal tissues of STZ-induced diabetic rats. Poorly controlled diabetes for 1 month cause augmented FN and p300 mRNA expression in association with reduced miR-146a levels in the kidney and heart (Fig. 5A–F). To further examine whether such changes occur also in type 2 diabetes, we examined retinal, renal, and cardiac tissues from db/db mice after 2 months of poorly controlled diabetes. At this time point, these animals developed several changes characteristic of chronic diabetes complications (20,28). Db/db mice demonstrated hyperglycemia (serum glucose; diabetes 29.1 ± 2.5 mmol/L and controls 8.9 ± 2.7 mmol/L, P < 0.05) and increased body weight (diabetes 44.4 ± 2.5 g and controls 34 ± 2.5 g, P < 0.05) compared with controls. Similar to the type 1 diabetes model, diabetic db/db mice showed augmented FN and p300 mRNA expression in the retina, kidney, and heart in association with reduced miR-146a levels (Fig. 6A–I).

Bottom Line: Cardiac and renal tissues were analyzed from type 1 and type 2 diabetic animals.Additional experiments showed that p300 regulates miR-146a.Similar changes were seen in the retinas, kidneys, and hearts in type 1 and type 2 diabetic animals.

View Article: PubMed Central - PubMed

Affiliation: Department of Pathology, Schulich School of Medicine and Dentistry and the University of Western Ontario, London, Ontario, Canada.

ABSTRACT

Objective: MicroRNAs (miRNAs), through transcriptional regulation, modulate several cellular processes. In diabetes, increased extracellular matrix protein fibronectin (FN) production is known to occur through histone acetylator p300. Here, we investigated the role of miR-146a, an FN-targeting miRNA, on FN production in diabetes and its relationship with p300.

Research design and methods: miR-146a expressions were measured in endothelial cells from large vessels and retinal microvessels in various glucose levels. FN messenger RNA expression and protein levels with or without miR-146a mimic or antagomir transfection were examined. A luciferase assay was performed to detect miR-146a's binding to FN 3'-untranslated region (UTR). Likewise, retinas from type 1 diabetic rats were studied with or without an intravitreal injection of miR-146a mimic. In situ hybridization was used to localize retinal miR-146a. Cardiac and renal tissues were analyzed from type 1 and type 2 diabetic animals.

Results: A total of 25 mmol/L glucose decreased miR-146a expression and increased FN expression compared with 5 mmol/L glucose in both cell types. miR-146a mimic transfection prevented such change, whereas miR-146a antagomir transfection in the cells in 5 mmol/L glucose caused FN upregulation. A luciferase assay confirmed miR-146a's binding to FN 3'-UTR. miR-146a was localized in the retinal endothelial cells and was decreased in diabetes. Intravitreal miR-146a mimic injection restored retinal miR-146a and decreased FN in diabetes. Additional experiments showed that p300 regulates miR-146a. Similar changes were seen in the retinas, kidneys, and hearts in type 1 and type 2 diabetic animals.

Conclusions: These studies showed a novel, glucose-induced molecular mechanism in which miR-146a participates in the transcriptional circuitry regulating extracellular matrix protein production in diabetes.

Show MeSH
Related in: MedlinePlus