Endogenous miR-204 Protects the Kidney against Chronic Injury in Hypertension and Diabetes
Authors: Cheng Yuan , Wang Dandan , Wang Feng , Liu Jing , Huang Baorui , Baker Maria Angeles , Yin Jianyong , Wu Rui , Liu Xuanchen , Regner Kevin R. , Usa Kristie , Liu Yong , Zhang Congxiao , Dong Lijin , Geurts Aron M. , Wang Niansong , Miller Sheldon S. , He Yongcheng , Liang Mingyu 
Published: June 2020

Significance Statement
Several microRNAs have been shown to play significant roles in the development of renal injury. The microRNA miR-204-5p is highly enriched in the kidney but its involvement in chronic renal injury is unknown. In this study, the authors report that miR-204-5p abundance is significantly decreased in kidney biopsy samples from patients with hypertension, hypertensive nephrosclerosis, or diabetic nephropathy. They also found, in a rat model of salt-sensitive hypertension, a mouse model of hypertension, and a mouse model of type 2 diabetes, inhibition of miR-204-5p, or deletion of the Mir204 gene results in upregulation of an injurious molecular pathway and substantial exacerbation of renal injury. These findings provide evidence of a prominent role for miR-204-5p in safeguarding the kidneys against common causes of chronic renal injury.

Background
Aberrant microRNA (miRNA) expression affects biologic processes and downstream genes that are crucial to CKD initiation or progression. The miRNA miR-204-5p is highly expressed in the kidney but whether miR-204-5p plays any role in the development of chronic renal injury is unknown.

Methods
We used real-time PCR to determine levels of miR-204 in human kidney biopsies and animal models. We generated Mir204 knockout mice and used locked nucleic acid–modified anti-miR to knock down miR-204-5p in mice and rats. We used a number of physiologic, histologic, and molecular techniques to analyze the potential role of miR-204-5p in three models of renal injury.

Results
Kidneys of patients with hypertension, hypertensive nephrosclerosis, or diabetic nephropathy exhibited a significant decrease in miR-204-5p compared with controls. Dahl salt-sensitive rats displayed lower levels of renal miR-204-5p compared with partially protected congenic SS.13BN26 rats. Administering anti–miR-204-5p to SS.13BN26 rats exacerbated interlobular artery thickening and renal interstitial fibrosis. In a mouse model of hypertensive renal injury induced by uninephrectomy, angiotensin II, and a high-salt diet, Mir204 gene knockout significantly exacerbated albuminuria, renal interstitial fibrosis, and interlobular artery thickening, despite attenuation of hypertension. In diabetic db/db mice, administering anti–miR-204-5p exacerbated albuminuria and cortical fibrosis without influencing blood glucose levels. In all three models, inhibiting miR-204-5p or deleting Mir204 led to upregulation of protein tyrosine phosphatase SHP2, a target gene of miR-204-5p, and increased phosphorylation of signal transducer and activator of transcription 3, or STAT3, which is an injury-promoting effector of SHP2.

Conclusions
These findings indicate that the highly expressed miR-204-5p plays a prominent role in safeguarding the kidneys against common causes of chronic renal injury.