Loss of Histone H3 K79 Methyltransferase Dot1l Facilitates Kidney Fibrosis by Upregulating Endothelin 1 through Histone Deacetylase 2
Authors: Zhang Long , Chen Lihe , Gao Chao , Chen Enuo , Lightle Andrea R. , Foulke Llewellyn , Zhao Bihong , Higgins Paul J. , Zhang Wenzheng 
Published: December 2019

Significance Statement

If and how endothelin 1, a potent vasoconstrictor with proinflammatory and profibrotic properties, is upregulated to promote CKD is largely unknown. Emerging evidence has suggested that histone H3 K79 methyltransferase Dot1l exerts an antifibrotic effect by repressing the gene encoding endothelin 1 (Edn1) in the connecting tubule/collecting duct. The authors demonstrate in connecting tubule/collecting duct–specificDot1lconditional knockout mice that disruption ofDot1lfacilitates CKD development by upregulating endothelin 1, and thatDot1landEdn1double-knockout mice have a significantly attenuated CKD phenotype. Dot1l and histone deacetylase 2 mutually inhibit their association with theEdn1promoter to regulate endothelin 1 production. This study is the first to defineDot1las an epigenetic modifier of CKD, establishes a new CKD mouse model, and reveals a novel mechanism regulatingEdn1transcription.

Background

The progression rate of CKD varies substantially among patients. The genetic and epigenetic contributions that modify how individual patients respond to kidney injury are largely unknown. Emerging evidence has suggested that histone H3 K79 methyltransferase Dot1l has an antifibrotic effect by repressingEdn1, which encodes endothelin 1 in the connecting tubule/collecting duct.

Methods

To determine if deletion of theDot1lgene is a genetic and epigenetic risk factor through regulatingEdn1,we studied four groups of mice: wild-type mice, connecting tubule/collecting duct–specificDot1lconditional knockout mice (Dot1lAC),Dot1landEdn1double-knockout mice (DEAC), andEdn1connecting tubule/collecting duct–specific conditional knockout mice (Edn1AC), under three experimental conditions (streptozotocin-induced diabetes, during normal aging, and after unilateral ureteral obstruction). We used several approaches (colocalization, glutathione S-transferase pulldown, coimmunoprecipitation, yeast two-hybrid, gel shift, and chromatin immunoprecipitation assays) to identify and confirm interaction of Dot1a (the majorDot1lsplicing variant in the mouse kidney) with histone deacetylase 2 (HDAC2), as well as the function of the Dot1a-HDAC2 complex in regulatingEdn1transcription.

Results

In each case,Dot1lACmice developed more pronounced kidney fibrosis and kidney malfunction compared with wild-type mice. TheseDot1lACphenotypes were ameliorated in the double-knockoutDEACmice. The interaction between Dot1a and HDAC2 prevents the Dot1a-HDAC2 complex from association with DNA, providing a counterbalancing mechanism governingEdn1transcription by modulating H3 K79 dimethylation and H3 acetylation at theEdn1promoter.

Conclusions

Our study confirmsDot1lto be a genetic and epigenetic modifier of kidney fibrosis, reveals a new mechanism regulatingEdn1transcription by Dot1a and HDAC2, and reinforces endothelin 1 as a therapeutic target of kidney fibrosis.