DACH1 protects podocytes from experimental diabetic injury and modulates PTIP-H3K4Me3 activity
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
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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Research Article Nephrology

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 5

Inducible podocyte-specific DACH1 overexpression protects from DKD.

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Inducible podocyte-specific DACH1 overexpression protects from DKD. (A) ...
(A) Western blotting using a DACH1-specific antibody on glomerular lysates of transgenic mice. DACH1 mice (TRE-Dach1; pod-rtTA) show robust induction of DACH1 expression after 1 week of DOX supplementation. (B) IF demonstrates that DACH1 overexpression is restricted to podocytes in DACH1 mice. Scale bars: 50 μm. (C) Blood glucose levels of 6-week-old OVE26 transgenic mice without or with induction of podocyte-specific DACH1 expression. (D) Measurements of 24-hour urinary albumin excretion immediately prior to euthanasia at age of 14 weeks. *P < 0.03. (E) Representative PAS-stained kidney sections. DACH1 kidneys under basal conditions appear morphologically normal. OVE26 mice show FSGS with associated tubular proteinaceous casts and mesangial expansion. FSGS was not evident in OVE26 littermates that also had podocyte-specific induction of DACH1. Scale bars: 40 μm (low power); 20 μm (high power). (F) Representative TEM images of OVE26 mice. OVE26 mice demonstrate widespread podocyte injury with loss of primary and secondary processes and diffuse foot-process effacement. OVE26 littermates that also have podocyte-specific expression of DACH1 show significant podocyte protection, including preservation of overall cellular morphology and foot-process architecture. Scale bars: 5 μm. (G) Percentage of glomeruli showing FSGS was calculated. *P < 0.002. (H–N) Morphometric measurements demonstrate that podocyte DACH1 overexpression mitigates the glomerular changes induced by the diabetes of OVE26. Quantification of (H) podocyte effacement (*P < 0.0001), (I) GBM thickness (*P < 0.0001), (J) average glomerular volume (*P < 0.0013), (K) total podocyte volume (*P < 0.0011), (L) mesangial volume (*P < 0.0067), (M) average individual podocyte volume (*P < 0.0031), and (N) podocyte numerical density (*P < 0.0022). (H and I) n = 3 mice per group. (J–N) Control, n = 6 mice; DACH1, OVE26, and OVE26 + DACH1 groups, n = 7 mice per group. Two-tailed Student’s t test (C, D, and G–N).