DACH1 protects podocytes from experimental diabetic injury and modulates PTIP-H3K4Me3 activity
Aili Cao, … , Katalin Susztak, Lewis Kaufman
Aili Cao, … , Katalin Susztak, Lewis Kaufman
Published May 17, 2021
Citation Information: J Clin Invest. 2021;131(10):e141279. https://doi.org/10.1172/JCI141279.
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DACH1 protects podocytes from experimental diabetic injury and modulates PTIP-H3K4Me3 activity

Abstract

Dachshund homolog 1 (DACH1), a key cell-fate determinant, regulates transcription by DNA sequence–specific binding. We identified diminished Dach1 expression in a large-scale screen for mutations that convert injury-resistant podocytes into injury-susceptible podocytes. In diabetic kidney disease (DKD) patients, podocyte DACH1 expression levels are diminished, a condition that strongly correlates with poor clinical outcomes. Global Dach1 KO mice manifest renal hypoplasia and die perinatally. Podocyte-specific Dach1 KO mice, however, maintain normal glomerular architecture at baseline, but rapidly exhibit podocyte injury after diabetes onset. Furthermore, podocyte-specific augmentation of DACH1 expression in mice protects from DKD. Combined RNA sequencing and in silico promoter analysis reveal conversely overlapping glomerular transcriptomic signatures between podocyte-specific Dach1 and Pax transactivation-domain interacting protein (Ptip) KO mice, with upregulated genes possessing higher-than-expected numbers of promoter Dach1-binding sites. PTIP, an essential component of the activating histone H3 lysine 4 trimethylation (H3K4Me3) complex, interacts with DACH1 and is recruited by DACH1 to its promoter-binding sites. DACH1-PTIP recruitment represses transcription and reduces promoter H3K4Me3 levels. DACH1 knockdown in podocytes combined with hyperglycemia triggers target gene upregulation and increases promoter H3K4Me3. These findings reveal that in DKD, diminished DACH1 expression enhances podocyte injury vulnerability via epigenetic derepression of its target genes.

Authors

Aili Cao, Jianhua Li, Morad Asadi, John M. Basgen, Bingbing Zhu, Zhengzi Yi, Song Jiang, Tomohito Doke, Osama El Shamy, Niralee Patel, Paolo Cravedi, Evren U. Azeloglu, Kirk N. Campbell, Madhav Menon, Steve Coca, Weijia Zhang, Hao Wang, Ke Zen, Zhihong Liu, Barbara Murphy, John C. He, Vivette D. D’Agati, Katalin Susztak, Lewis Kaufman

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Figure 6

Combining transcriptomic and in silico promoter analyses to identify direct DACH1 transcriptional target genes in podocytes.

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Combining transcriptomic and in silico promoter analyses to identify dir...
(A) RNA-Seq was performed to compare glomerular transcriptomes of control and Dach1 podocyte-specific KO mice at baseline and early after STZ-induced DM. Results were overlapped with a previously reported microarray of podocyte-specific Ptip KO mice under basal conditions (38). Twenty out of a total of 38 genes from the Ptip KO glomeruli were also dysregulated in Dach1 KO glomeruli. Genome-wide in silico promoter analysis using a previously reported positional weight matrix (4) found the upregulated genes in this Dach1-Ptip overlap set to be highly enriched for the presence of at least 1 promoter DBD. Gene names surrounded by a red rectangle indicate dysregulation in glomeruli of Dach1 KO mice under basal conditions. Asterisks indicate the presence of promoter DBD. (B) Glomerular mRNA levels of the upregulated Dach1-Ptip overlap gene set in a previously reported microarray analysis of db/db mice (39) and subjected to further analysis by Nephroseq. All genes present on the microarray chip from the overlap set are also upregulated to varying degrees in this diabetes model. (C) Glomerular mRNA levels of the DACH1 target gene NELL2 are increased in human DKD. Data are from a previously reported microarray study (40) and subjected to further analysis by Nephroseq. *P < 0.001. (D) NELL2 fluorescent staining intensity is increased in glomeruli in human nephrectomy samples with a clinicopathological diagnosis of DKD (n = 3) compared with normal controls (n = 4). Representative images taken with identical exposure times are shown. In kidney overall, NELL2 expression is highly enriched in podocytes. Scale bars: 100 μm. (E) Differences in NELL2 glomerular fluorescent intensity between DKD (n = 50) and control (n = 50) were quantified relative to DAPI (*P < 0.0005) and to WT1 (**P < 0.0001). (C and E) Two-tailed Student’s t test.