Long noncoding RNA Tug1 regulates mitochondrial bioenergetics in diabetic nephropathy
Jianyin Long, … , Paul A. Overbeek, Farhad R. Danesh
Jianyin Long, … , Paul A. Overbeek, Farhad R. Danesh
Published November 1, 2016; First published October 17, 2016
Citation Information: J Clin Invest. 2016;126(11):4205-4218. https://doi.org/10.1172/JCI87927.
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Research Article Nephrology

Long noncoding RNA Tug1 regulates mitochondrial bioenergetics in diabetic nephropathy

Abstract

The regulatory roles of long noncoding RNAs (lncRNAs) in transcriptional coactivators are still largely unknown. Here, we have shown that the peroxisome proliferator–activated receptor γ (PPARγ) coactivator α (PGC-1α, encoded by Ppargc1a) is functionally regulated by the lncRNA taurine-upregulated gene 1 (Tug1). Further, we have described a role for Tug1 in the regulation of mitochondrial function in podocytes. Using a murine model of diabetic nephropathy (DN), we performed an unbiased RNA-sequencing (RNA-seq) analysis of kidney glomeruli and identified Tug1 as a differentially expressed lncRNA in the diabetic milieu. Podocyte-specific overexpression (OE) of Tug1 in diabetic mice improved the biochemical and histological features associated with DN. Unexpectedly, we found that Tug1 OE rescued the expression of PGC-1α and its transcriptional targets. Tug1 OE was also associated with improvements in mitochondrial bioenergetics in the podocytes of diabetic mice. Mechanistically, we found that the interaction between Tug1 and PGC-1α promotes the binding of PGC-1α to its own promoter. We identified a Tug1-binding element (TBE) upstream of the Ppargc1a gene and showed that Tug1 binds with the TBE to enhance Ppargc1a promoter activity. These findings indicate that a direct interaction between PGC-1α and Tug1 modulates mitochondrial bioenergetics in podocytes in the diabetic milieu.

Authors

Jianyin Long, Shawn S. Badal, Zengchun Ye, Yin Wang, Bernard A. Ayanga, Daniel L. Galvan, Nathanael H. Green, Benny H. Chang, Paul A. Overbeek, Farhad R. Danesh

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Figure 2

Tug1 mediates expression of PGC-1α pathway genes.

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Tug1 mediates expression of PGC-1α pathway genes. (A) Gene expression a...
(A) Gene expression analysis of RNA from pGIPZ-shControl (shCtrl) or shTug1 lentivirus–transduced podocytes used for microarray analysis. (B) Volcano plot of microarray data generated from Tug1-KD podocytes compared with controls. A cutoff of a log2 fold-change greater than 2 and a –log10 (P value) greater than 1 was used for downstream pathway analysis. (C–E) Bioinformatics analysis of differentially regulated Tug1 target genes. (C and D) Biological processes GO terms from genes differentially up- and downregulated by Tug1. (E) Pathway analysis of Tug1-downregulated genes. (F) Hierarchical clustering analysis of RNA expression levels of PGC-1α–related genes in control podocytes compared with podocytes harboring stable KD of Tug1. Yellow boxes highlight genes that are direct targets of PGC-1α, and red boxes highlight its upstream regulators. (G) qPCR validation of several direct targets of PGC-1α. Expression values were normalized to Gapdh internal controls. Cell culture experiments were repeated at least 3 times. *P < 0.05, **P < 0.01, and ***P < 0.001 by 2-tailed Student’s t test (A and G). See Supplemental Methods for the data analysis steps related to B–F. Data are expressed as the mean ± SEM.