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Increased RhoA translocation in renal cortex of diabetic rats
Amber R Massey1, Liyang Miao, Brandi N Smith
1Department of Physiology and Biophysics, University of Mississippi Medical Center, Jackson, MS 39216, USA.
Abstract:
RhoA, a member of the Rho small G protein family, mediates multiple intracellular signaling pathways, and is highly expressed in renal cortex. RhoA translocation is associated with RhoA activation. This study was undertaken to examine the relation of translocation of RhoA in the renal cortex with diabetic renal injury in streptozotocin (STZ)-induced diabetic rats. Male Sprague-Dawley rats were divided into control and diabetic groups and were studied at 8 weeks after STZ-injection (55 mg/kg, i.v). We found that the kidney weight and urinary protein excretion were significantly increased in diabetic rats. Diabetic glomerulopathy was confirmed by mesangial matrix expanding and glomerular basement membrane thickening. The ratio of membrane-bound RhoA verses cytosolic RhoA is 1.8 fold higher (p < 0.01) in diabetic group, indicating an enhanced RhoA translocation. There was no significant difference in total RhoA protein expression and RhoA mRNA expression between diabetic and control groups. These data suggest that RhoA translocation might be involved in diabetic renal injury.
Insights
Diabetic renal injury in rats involves increased RhoA translocation to the kidney cortex membrane. This activation occurs without changes in total RhoA protein or mRNA levels, suggesting a specific role for RhoA movement in kidney damage.
Area of Science:
- Nephrology
- Molecular Biology
- Endocrinology
Background:
- RhoA, a Rho small G protein, regulates intracellular signaling and is abundant in the renal cortex.
- RhoA activation is linked to its translocation within cells.
- Diabetic nephropathy is a significant complication of diabetes mellitus.
Purpose of the Study:
- To investigate the association between RhoA translocation in the renal cortex and diabetic renal injury.
- To determine if RhoA activation, specifically translocation, plays a role in the pathogenesis of diabetic kidney disease.
Main Methods:
- Streptozotocin (STZ)-induced diabetic rat model.
- Assessment of kidney weight and urinary protein excretion at 8 weeks post-STZ injection.
- Histopathological examination for diabetic glomerulopathy.
- Quantification of membrane-bound versus cytosolic RhoA.
Main Results:
- Diabetic rats exhibited increased kidney weight and urinary protein excretion.
- Histopathology confirmed diabetic glomerulopathy, including mesangial expansion and GBM thickening.
- A significant 1.8-fold increase in the ratio of membrane-bound to cytosolic RhoA was observed in diabetic rats (p < 0.01).
- No significant differences in total RhoA protein or mRNA expression were found between groups.
Conclusions:
- RhoA translocation to the membrane is enhanced in the renal cortex of STZ-induced diabetic rats.
- These findings suggest that RhoA translocation, rather than altered expression, is implicated in the development of diabetic renal injury.
- Targeting RhoA translocation may offer a therapeutic strategy for diabetic nephropathy.