title: KANK deficiency leads to podocyte dysfunction and nephrotic syndrome.
abstract: Steroid-resistant nephrotic syndrome (SRNS) is a frequent cause of progressive renal function decline and affects millions of people. In a recent study, 30% of SRNS cases evaluated were the result of monogenic mutations in 1 of 27 different genes. Here, using homozygosity mapping and whole-exome sequencing, we identified recessive mutations in kidney ankyrin repeat-containing protein 1 (KANK1), KANK2, and KANK4 in individuals with nephrotic syndrome. In an independent functional genetic screen of Drosophila cardiac nephrocytes, which are equivalents of mammalian podocytes, we determined that the Drosophila KANK homolog (dKank) is essential for nephrocyte function. RNAi-mediated knockdown of dKank in nephrocytes disrupted slit diaphragm filtration structures and lacuna channel structures. In rats, KANK1, KANK2, and KANK4 all localized to podocytes in glomeruli, and KANK1 partially colocalized with synaptopodin. Knockdown of kank2 in zebrafish recapitulated a nephrotic syndrome phenotype, resulting in proteinuria and podocyte foot process effacement. In rat glomeruli and cultured human podocytes, KANK2 interacted with ARHGDIA, a known regulator of RHO GTPases in podocytes that is dysfunctional in some types of nephrotic syndrome. Knockdown of KANK2 in cultured podocytes increased active GTP-bound RHOA and decreased migration. Together, these data suggest that KANK family genes play evolutionarily conserved roles in podocyte function, likely through regulating RHO GTPase signaling.
authors.forename: Heon Yung
authors.initials: HY
authors.lastname: Gee
authors.forename: Fujian
authors.initials: F
authors.lastname: Zhang
authors.forename: Shazia
authors.initials: S
authors.lastname: Ashraf
authors.forename: Stefan
authors.initials: S
authors.lastname: Kohl
authors.forename: Carolin E
authors.initials: CE
authors.lastname: Sadowski
authors.forename: Virginia
authors.initials: V
authors.lastname: Vega-Warner
authors.forename: Weibin
authors.initials: W
authors.lastname: Zhou
authors.forename: Svjetlana
authors.initials: S
authors.lastname: Lovric
authors.forename: Humphrey
authors.initials: H
authors.lastname: Fang
authors.forename: Margaret
authors.initials: M
authors.lastname: Nettleton
authors.forename: Jun-yi
authors.initials: JY
authors.lastname: Zhu
authors.forename: Julia
authors.initials: J
authors.lastname: Hoefele
authors.forename: Lutz T
authors.initials: LT
authors.lastname: Weber
authors.forename: Ludmila
authors.initials: L
authors.lastname: Podracka
authors.forename: Andrej
authors.initials: A
authors.lastname: Boor
authors.forename: Henry
authors.initials: H
authors.lastname: Fehrenbach
authors.forename: Jeffrey W
authors.initials: JW
authors.lastname: Innis
authors.forename: Joseph
authors.initials: J
authors.lastname: Washburn
authors.forename: Shawn
authors.initials: S
authors.lastname: Levy
authors.forename: Richard P
authors.initials: RP
authors.lastname: Lifton
authors.forename: Edgar A
authors.initials: EA
authors.lastname: Otto
authors.forename: Zhe
authors.initials: Z
authors.lastname: Han
authors.forename: Friedhelm
authors.initials: F
authors.lastname: Hildebrandt
mesh_terms: D048868:Adaptor Proteins, Signal Transducing; D000818:Animals; D002460:Cell Line; D003598:Cytoskeletal Proteins; D029721:Drosophila Proteins / Q000235:genetics / Q000378:metabolism; D004331:Drosophila melanogaster; D005260:Female; D055785:Gene Knockdown Techniques; D006801:Humans; D008297:Male; D008840:Microfilament Proteins / Q000235:genetics / Q000378:metabolism; D009154:Mutation; D009404:Nephrotic Syndrome / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D050199:Podocytes / Q000378:metabolism / Q000473:pathology; D011507:Proteinuria / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D051381:Rats; D025521:Tumor Suppressor Proteins / Q000172:deficiency / Q000378:metabolism; D015027:Zebrafish / Q000235:genetics / Q000378:metabolism; D029961:Zebrafish Proteins / Q000235:genetics / Q000378:metabolism
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D003598:Cytoskeletal Proteins; D029721:Drosophila Proteins; C467739:KANK1 protein, human; D008840:Microfilament Proteins; C503967:SYNPO protein, human; C503969:Synpo protein, rat; D025521:Tumor Suppressor Proteins; D029961:Zebrafish Proteins