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Therapeutic potential of Nrf2 activators in streptozotocin-induced diabetic nephropathy.

Zheng H, Whitman SA, Wu W, Wondrak GT, Wong PK, Fang D, Zhang DD - Diabetes (2011)

Bottom Line: Changes in protein expression of the Nrf2 pathway, as well as transforming growth factor-β1 (TGF-β1), fibronectin (FN), collagen IV, and p21/WAF1Cip1 (p21) were analyzed.Nrf2 activation reduced oxidative damage and suppressed the expression of TGF-β1, extracellular matrix proteins and p21 both in vivo and in HRMCs.In addition, Nrf2 activation reverted p21-mediated growth inhibition and hypertrophy of HRMCs under hyperglycemic conditions.

View Article: PubMed Central - PubMed

Affiliation: Department of Pharmacology and Toxicology, University of Arizona, Tucson, Arizona, USA.

ABSTRACT

Objective: To determine whether dietary compounds targeting NFE2-related factor 2 (Nrf2) activation can be used to attenuate renal damage and preserve renal function during the course of streptozotocin (STZ)-induced diabetic nephropathy.

Research design and methods: Diabetes was induced in Nrf2(+/+) and Nrf2(-/-) mice by STZ injection. Sulforaphane (SF) or cinnamic aldehyde (CA) was administered 2 weeks after STZ injection and metabolic indices and renal structure and function were assessed (18 weeks). Markers of diabetes including blood glucose, insulin, polydipsia, polyuria, and weight loss were measured. Pathological alterations and oxidative damage in glomeruli were also determined. Changes in protein expression of the Nrf2 pathway, as well as transforming growth factor-β1 (TGF-β1), fibronectin (FN), collagen IV, and p21/WAF1Cip1 (p21) were analyzed. The molecular mechanisms of Nrf2-mediated protection were investigated in an in vitro model using human renal mesangial cells (HRMCs).

Results: SF or CA significantly attenuated common metabolic disorder symptoms associated with diabetes in Nrf2(+/+) but not in Nrf2(-/-) mice, indicating SF and CA function through specific activation of the Nrf2 pathway. Furthermore, SF or CA improved renal performance and minimized pathological alterations in the glomerulus of STZ-Nrf2(+/+) mice. Nrf2 activation reduced oxidative damage and suppressed the expression of TGF-β1, extracellular matrix proteins and p21 both in vivo and in HRMCs. In addition, Nrf2 activation reverted p21-mediated growth inhibition and hypertrophy of HRMCs under hyperglycemic conditions.

Conclusions: We provide experimental evidence indicating that dietary compounds targeting Nrf2 activation can be used therapeutically to improve metabolic disorder and relieve renal damage induced by diabetes.

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Related in: MedlinePlus

Activation of Nrf2 diminishes mesangial ROS generation under hyperglycemic conditions. A: Nrf2 expression and localization were assessed in HRMCs incubated in NG, HG, HG+tBHQ, HG+SF, or HG+CA DMEM media for 48 h. Incubation in HG as well as treatment with an Nrf2 activator increased Nrf2 staining intensity and localization to the nucleus. B: Protein expression of Nrf2 and downstream targets was analyzed in HRMCs incubated in NG, HG, HG+tBHQ, HG+SF, or HG+CA DMEM media for 48 h. Representative Western blots and the relative quantification are provided. C: ROS levels in HRMCs incubated in NG, HG, HG+tBHQ, HG+SF, or HG+CA DMEM media are reported. HG stimulated ROS in HRMCs, whereas cotreatment with an Nrf2 activator for 48 h significantly reduced ROS. Data are expressed as mean ± SD (n = 3). *P < 0.05 compared with NG group. #P < 0.05 Nrf2 activators compared with HG alone. DCF, dichlorodihydrofluorescein diacetate. (A high-quality color representation of this figure is available in the online issue.)
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Figure 5: Activation of Nrf2 diminishes mesangial ROS generation under hyperglycemic conditions. A: Nrf2 expression and localization were assessed in HRMCs incubated in NG, HG, HG+tBHQ, HG+SF, or HG+CA DMEM media for 48 h. Incubation in HG as well as treatment with an Nrf2 activator increased Nrf2 staining intensity and localization to the nucleus. B: Protein expression of Nrf2 and downstream targets was analyzed in HRMCs incubated in NG, HG, HG+tBHQ, HG+SF, or HG+CA DMEM media for 48 h. Representative Western blots and the relative quantification are provided. C: ROS levels in HRMCs incubated in NG, HG, HG+tBHQ, HG+SF, or HG+CA DMEM media are reported. HG stimulated ROS in HRMCs, whereas cotreatment with an Nrf2 activator for 48 h significantly reduced ROS. Data are expressed as mean ± SD (n = 3). *P < 0.05 compared with NG group. #P < 0.05 Nrf2 activators compared with HG alone. DCF, dichlorodihydrofluorescein diacetate. (A high-quality color representation of this figure is available in the online issue.)

Mentions: Mesangial cells play a crucial role in dictating the function of glomeruli. To understand the molecular mechanism(s) by which activation of Nrf2 is able to preserve renal function during the progression of diabetic nephropathy, cultured primary HRMCs were used. HRMCs growing in NG (5.5 mmol/L) media were shifted to either NG (plus 19.5 mmol/L mannitol) or HG (25 mmol/L) media to mimic hyperglycemic conditions in the presence or absence of an Nrf2 activator. Similar to the results reported above in the animal model of STZ-induced diabetes, culturing HRMCs under hyperglycemic conditions also activated the Nrf2 pathway (Fig. 5A and B), presumably through oxidative stress.


Therapeutic potential of Nrf2 activators in streptozotocin-induced diabetic nephropathy.

Zheng H, Whitman SA, Wu W, Wondrak GT, Wong PK, Fang D, Zhang DD - Diabetes (2011)

Activation of Nrf2 diminishes mesangial ROS generation under hyperglycemic conditions. A: Nrf2 expression and localization were assessed in HRMCs incubated in NG, HG, HG+tBHQ, HG+SF, or HG+CA DMEM media for 48 h. Incubation in HG as well as treatment with an Nrf2 activator increased Nrf2 staining intensity and localization to the nucleus. B: Protein expression of Nrf2 and downstream targets was analyzed in HRMCs incubated in NG, HG, HG+tBHQ, HG+SF, or HG+CA DMEM media for 48 h. Representative Western blots and the relative quantification are provided. C: ROS levels in HRMCs incubated in NG, HG, HG+tBHQ, HG+SF, or HG+CA DMEM media are reported. HG stimulated ROS in HRMCs, whereas cotreatment with an Nrf2 activator for 48 h significantly reduced ROS. Data are expressed as mean ± SD (n = 3). *P < 0.05 compared with NG group. #P < 0.05 Nrf2 activators compared with HG alone. DCF, dichlorodihydrofluorescein diacetate. (A high-quality color representation of this figure is available in the online issue.)
© Copyright Policy - creative-commons
Related In: Results  -  Collection

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Show All Figures
getmorefigures.php?uid=PMC3198067&req=5

Figure 5: Activation of Nrf2 diminishes mesangial ROS generation under hyperglycemic conditions. A: Nrf2 expression and localization were assessed in HRMCs incubated in NG, HG, HG+tBHQ, HG+SF, or HG+CA DMEM media for 48 h. Incubation in HG as well as treatment with an Nrf2 activator increased Nrf2 staining intensity and localization to the nucleus. B: Protein expression of Nrf2 and downstream targets was analyzed in HRMCs incubated in NG, HG, HG+tBHQ, HG+SF, or HG+CA DMEM media for 48 h. Representative Western blots and the relative quantification are provided. C: ROS levels in HRMCs incubated in NG, HG, HG+tBHQ, HG+SF, or HG+CA DMEM media are reported. HG stimulated ROS in HRMCs, whereas cotreatment with an Nrf2 activator for 48 h significantly reduced ROS. Data are expressed as mean ± SD (n = 3). *P < 0.05 compared with NG group. #P < 0.05 Nrf2 activators compared with HG alone. DCF, dichlorodihydrofluorescein diacetate. (A high-quality color representation of this figure is available in the online issue.)
Mentions: Mesangial cells play a crucial role in dictating the function of glomeruli. To understand the molecular mechanism(s) by which activation of Nrf2 is able to preserve renal function during the progression of diabetic nephropathy, cultured primary HRMCs were used. HRMCs growing in NG (5.5 mmol/L) media were shifted to either NG (plus 19.5 mmol/L mannitol) or HG (25 mmol/L) media to mimic hyperglycemic conditions in the presence or absence of an Nrf2 activator. Similar to the results reported above in the animal model of STZ-induced diabetes, culturing HRMCs under hyperglycemic conditions also activated the Nrf2 pathway (Fig. 5A and B), presumably through oxidative stress.

Bottom Line: Changes in protein expression of the Nrf2 pathway, as well as transforming growth factor-β1 (TGF-β1), fibronectin (FN), collagen IV, and p21/WAF1Cip1 (p21) were analyzed.Nrf2 activation reduced oxidative damage and suppressed the expression of TGF-β1, extracellular matrix proteins and p21 both in vivo and in HRMCs.In addition, Nrf2 activation reverted p21-mediated growth inhibition and hypertrophy of HRMCs under hyperglycemic conditions.

View Article: PubMed Central - PubMed

Affiliation: Department of Pharmacology and Toxicology, University of Arizona, Tucson, Arizona, USA.

ABSTRACT

Objective: To determine whether dietary compounds targeting NFE2-related factor 2 (Nrf2) activation can be used to attenuate renal damage and preserve renal function during the course of streptozotocin (STZ)-induced diabetic nephropathy.

Research design and methods: Diabetes was induced in Nrf2(+/+) and Nrf2(-/-) mice by STZ injection. Sulforaphane (SF) or cinnamic aldehyde (CA) was administered 2 weeks after STZ injection and metabolic indices and renal structure and function were assessed (18 weeks). Markers of diabetes including blood glucose, insulin, polydipsia, polyuria, and weight loss were measured. Pathological alterations and oxidative damage in glomeruli were also determined. Changes in protein expression of the Nrf2 pathway, as well as transforming growth factor-β1 (TGF-β1), fibronectin (FN), collagen IV, and p21/WAF1Cip1 (p21) were analyzed. The molecular mechanisms of Nrf2-mediated protection were investigated in an in vitro model using human renal mesangial cells (HRMCs).

Results: SF or CA significantly attenuated common metabolic disorder symptoms associated with diabetes in Nrf2(+/+) but not in Nrf2(-/-) mice, indicating SF and CA function through specific activation of the Nrf2 pathway. Furthermore, SF or CA improved renal performance and minimized pathological alterations in the glomerulus of STZ-Nrf2(+/+) mice. Nrf2 activation reduced oxidative damage and suppressed the expression of TGF-β1, extracellular matrix proteins and p21 both in vivo and in HRMCs. In addition, Nrf2 activation reverted p21-mediated growth inhibition and hypertrophy of HRMCs under hyperglycemic conditions.

Conclusions: We provide experimental evidence indicating that dietary compounds targeting Nrf2 activation can be used therapeutically to improve metabolic disorder and relieve renal damage induced by diabetes.

Show MeSH
Related in: MedlinePlus