MiR-135a promotes renal fibrosis in diabetic nephropathy by regulating TRPC1
1Department of Nephrology, The First Affiliated Hospital, Sun Yat-Sen University, 58th, Zhongshan Road II, 510080, Guangzhou, People's Republic of China.
Aims/Hypothesis:
The contribution of aberrantly expressed microRNAs (miRNAs) to diabetic nephropathy in vivo is poorly understood.
Methods:
Integrated comparative miRNA array profiling was used to examine the expression of serum miRNAs in patients with diabetic nephropathy. The abundance of miRNA-135a (miR-135a) was measured by real-time quantitative PCR in the serum and kidney tissues of patients with diabetic nephropathy. The luciferase assay combined with mutation and immunoblotting was used to screen and verify the bioinformatically predicted miRNAs. Ca(2+) entry or intracellular Ca(2+) ([Ca(2+)]i) was performed by imaging Fura-2/AM-loaded cells using a fluorescence microscopy system. The role of miR-135a in vivo was explored with locked nucleic acid antisense oligonucleotides.
Results:
MiR-135a was markedly upregulated in serum and renal tissue from patients with diabetic nephropathy, as well from db/db mice, and this was associated with the development of microalbuminuria and renal fibrosis. Furthermore, we identified transient receptor potential cation channel, subfamily C, member 1 (TRPC1) as a target of miR-135a during renal injury. We demonstrated that overexpression of TRPC1 was able to reverse the pathological effects of miR-135a on promoting proliferation of mesangial cells and increasing synthesis of extracellular matrix proteins. Moreover, miR-135a attenuated store depletion-induced Ca(2+) entry into cells by regulating TRPC1. Importantly, knockdown of miR-135a in diabetic kidneys restored levels of TRPC1 and reduced synthesis of fibronectin and collagen I in vivo. Suppressing TRPC1 levels to prevent Ca(2+) entry into cells may be a mechanism whereby miR-135a promotes renal fibrosis in diabetic kidney injury.
Conclusions/Interpretation:
These findings suggest an important role for miR-135a in renal fibrosis and inhibition of miR-135a might be an effective therapy for diabetic nephropathy.
Insights
MicroRNA-135a (miR-135a) is upregulated in diabetic nephropathy, promoting renal fibrosis by targeting TRPC1. Inhibiting miR-135a may offer a novel therapy for this condition.
Area of Science:
- Nephrology
- Molecular Biology
- Biochemistry
Background:
- Diabetic nephropathy (DN) is a major complication of diabetes, characterized by progressive kidney damage.
- The role of microRNAs (miRNAs) in the pathogenesis of DN is not fully understood.
- Aberrant miRNA expression is implicated in various kidney diseases.
Purpose of the Study:
- To investigate the role of aberrantly expressed miRNAs in diabetic nephropathy in vivo.
- To identify specific miRNAs contributing to DN pathogenesis.
- To explore potential therapeutic targets for DN.
Main Methods:
- Comparative miRNA array profiling of serum from DN patients.
- Quantification of miRNA-135a (miR-135a) in serum and kidney tissue using real-time PCR.
- Luciferase assays, mutation analysis, and immunoblotting to validate miRNA targets.
- Intracellular calcium ([Ca(2+)]i) imaging and in vivo studies using locked nucleic acid antisense oligonucleotides.
Main Results:
- miR-135a was significantly upregulated in serum and kidney tissues of DN patients and db/db mice, correlating with microalbuminuria and renal fibrosis.
- Transient receptor potential cation channel, subfamily C, member 1 (TRPC1) was identified as a direct target of miR-135a.
- Overexpression of TRPC1 reversed miR-135a-induced mesangial cell proliferation and extracellular matrix synthesis.
- miR-135a attenuated Ca(2+) entry by regulating TRPC1, suggesting a mechanism for promoting renal fibrosis.
Conclusions:
- miR-135a plays a critical role in promoting renal fibrosis in diabetic nephropathy.
- Targeting miR-135a represents a potential therapeutic strategy for DN.
- The miR-135a/TRPC1 axis is a key pathway in DN pathogenesis.
