title: Aqp5 is a new transcriptional target of Dot1a and a regulator of Aqp2.
abstract: Dot1l encodes histone H3 K79 methyltransferase Dot1a. Mice with Dot1l deficiency in renal Aqp2-expressing cells (Dot1l(AC)) develop polyuria by unknown mechanisms. Here, we report that Aqp5 links Dot1l deletion to polyuria through Aqp2. cDNA array analysis revealed and real-time RT-qPCR validated Aqp5 as the most upregulated gene in Dot1l(AC) vs. control mice. Aqp5 protein is barely detectable in controls, but robustly expressed in the Dot1l(AC) kidneys, where it colocalizes with Aqp2. The upregulation of Aqp5 is coupled with reduced association of Dot1a and H3 dimethyl K79 with specific subregions in Aqp5 5' flanking region in Dot1l(AC) vs. control mice. In vitro studies in IMCD3, MLE-15 and 293Tcells using multiple approaches including real-time RT-qPCR, luciferase reporter assay, cell surface biotinylation assay, colocalization, and co-immunoprecipitation uncovered that Dot1a represses Aqp5. Human AQP5 interacts with AQP2 and impairs its cell surface localization. The AQP5/AQP2 complex partially resides in the ER/Golgi. Consistently, AQP5 is expressed in none of 15 normal controls, but in all of 17 kidney biopsies from patients with diabetic nephropathy. In the patients with diabetic nephropathy, AQP5 colocalizes with AQP2 in the perinuclear region and AQP5 expression is associated with impaired cellular H3 dimethyl K79. Taken together, these data for the first time identify Aqp5 as a Dot1a potential transcriptional target, and an Aqp2 binding partner and regulator, and suggest that the upregulated Aqp5 may contribute to polyuria, possibly by impairing Aqp2 membrane localization, in Dot1l(AC) mice and in patients with diabetic nephropathy.
authors: Department of Internal Medicine, The University of Texas Health Science Center at Houston, Houston, Texas, United States of America.
authors: Hongyu
authors: H
authors: Wu
authors: Lihe
authors: L
authors: Chen
authors: Xi
authors: X
authors: Zhang
authors: Qiaoling
authors: Q
authors: Zhou
authors: Ju-Mei
authors: JM
authors: Li
authors: Stefan
authors: S
authors: Berger
authors: Zea
authors: Z
authors: Borok
authors: Beiyun
authors: B
authors: Zhou
authors: Zhou
authors: Z
authors: Xiao
authors: Hongling
authors: H
authors: Yin
authors: Mingyao
authors: M
authors: Liu
authors: Ying
authors: Y
authors: Wang
authors: Jianping
authors: J
authors: Jin
authors: Michael R
authors: MR
authors: Blackburn
authors: Yang
authors: Y
authors: Xia
authors: Wenzheng
authors: W
authors: Zhang
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D051399:Aquaporin 2 / Q000235:genetics / Q000378:metabolism*; D051402:Aquaporin 5 / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D001483:Base Sequence; D002467:Cell Nucleus / Q000378:metabolism; D047369:Chromatin Immunoprecipitation; D003928:Diabetic Nephropathies / Q000150:complications / Q000235:genetics / Q000473:pathology; D004721:Endoplasmic Reticulum / Q000378:metabolism; D006056:Golgi Apparatus / Q000378:metabolism; D011495:Histone-Lysine N-Methyltransferase; D006657:Histones / Q000378:metabolism; D006801:Humans; D007668:Kidney / Q000378:metabolism / Q000473:pathology; D008239:Lysine / Q000378:metabolism; D008745:Methylation; D008780:Methyltransferases / Q000378:metabolism*; D051379:Mice; D008969:Molecular Sequence Data; D020411:Oligonucleotide Array Sequence Analysis; D011141:Polyuria / Q000150:complications / Q000235:genetics / Q000473:pathology; D011485:Protein Binding; D021381:Protein Transport; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D012045:Regulatory Sequences, Nucleic Acid / Q000235:genetics; D014158:Transcription, Genetic; D015854:Up-Regulation / Q000235:genetics
chemical_list: D051399:Aquaporin 2; D051402:Aquaporin 5; D006657:Histones; D012333:RNA, Messenger; C481527:Dot1l protein, mouse; D008780:Methyltransferases; D011495:Histone-Lysine N-Methyltransferase; D008239:Lysine