title: Multistep regulation of autophagy by WNK1.
abstract: The with-no-lysine (K) (WNK) kinases are an atypical family of protein kinases that regulate ion transport across cell membranes. Mutations that result in their overexpression cause hypertension-related disorders in humans. Of the four mammalian WNKs, only WNK1 is expressed throughout the body. We report that WNK1 inhibits autophagy, an intracellular degradation pathway implicated in several human diseases. Using small-interfering RNA-mediated WNK1 knockdown, we show autophagosome formation and autophagic flux are accelerated. In cells with reduced WNK1, basal and starvation-induced autophagy is increased. We also show that depletion of WNK1 stimulates focal class III phosphatidylinositol 3-kinase complex (PI3KC3) activity, which is required to induce autophagy. Depletion of WNK1 increases the expression of the PI3KC3 upstream regulator unc-51-like kinase 1 (ULK1), its phosphorylation, and activation of the kinase upstream of ULK1, the AMP-activated protein kinase. In addition, we show that the N-terminal region of WNK1 binds to the UV radiation resistance-associated gene (UVRAG) in vitro and WNK1 partially colocalizes with UVRAG, a component of a PI3KC3 complex. This colocalization decreases upon starvation of cells. Depletion of the SPS/STE20-related proline-alanine-rich kinase, a WNK1-activated enzyme, also induces autophagy in nutrient-replete or -starved conditions, but depletion of the related kinase and WNK1 substrate, oxidative stress responsive 1, does not. These results indicate that WNK1 inhibits autophagy by multiple mechanisms.
authors.affiliation: Department of Pharmacology, University of Texas Southwestern Medical Center, Dallas, TX 75390.
authors.forename: Sachith
authors.initials: S
authors.lastname: Gallolu Kankanamalage
authors.affiliation: Department of Pharmacology, University of Texas Southwestern Medical Center, Dallas, TX 75390.
authors.forename: A-Young
authors.initials: AY
authors.lastname: Lee
authors.affiliation: Department of Pharmacology, University of Texas Southwestern Medical Center, Dallas, TX 75390.
authors.forename: Chonlarat
authors.initials: C
authors.lastname: Wichaidit
authors.affiliation: Department of Pharmacology, University of Texas Southwestern Medical Center, Dallas, TX 75390.
authors.forename: Andres
authors.initials: A
authors.lastname: Lorente-Rodriguez
authors.affiliation: Department of Pharmacology, University of Texas Southwestern Medical Center, Dallas, TX 75390.
authors.forename: Akansha M
authors.initials: AM
authors.lastname: Shah
authors.affiliation: Department of Pharmacology, University of Texas Southwestern Medical Center, Dallas, TX 75390.
authors.forename: Steve
authors.initials: S
authors.lastname: Stippec
authors.affiliation: Harold C. Simmons Comprehensive Cancer Center, University of Texas Southwestern Medical Center, Dallas, TX 75390.
authors.forename: Angelique W
authors.initials: AW
authors.lastname: Whitehurst
authors.affiliation: Department of Pharmacology, University of Texas Southwestern Medical Center, Dallas, TX 75390; melanie.cobb@utsouthwestern.edu.|Harold C. Simmons Comprehensive Cancer Center, University of Texas Southwestern Medical Center, Dallas, TX 75390.
authors.forename: Melanie H
authors.initials: MH
authors.lastname: Cobb
mesh_terms: D001343:Autophagy / Q000235:genetics / Q000502:physiology*; D000071189:Autophagy-Related Protein-1 Homolog / Q000378:metabolism; D002460:Cell Line; D058546:Class III Phosphatidylinositol 3-Kinases / Q000378:metabolism; D055785:Gene Knockdown Techniques; D006367:HeLa Cells; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins / Q000378:metabolism; D008954:Models, Biological; D017346:Protein Serine-Threonine Kinases / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism; D034741:RNA, Small Interfering / Q000235:genetics; D025521:Tumor Suppressor Proteins / Q000235:genetics / Q000378:metabolism; D000076204:WNK Lysine-Deficient Protein Kinase 1 / Q000037:antagonists & inhibitors / Q000235:genetics / Q000502:physiology*
chemical_list: D047908:Intracellular Signaling Peptides and Proteins; D034741:RNA, Small Interfering; D025521:Tumor Suppressor Proteins; C408122:UVRAG protein, human; C118135:OXSR1 protein, human; D058546:Class III Phosphatidylinositol 3-Kinases; D000071189:Autophagy-Related Protein-1 Homolog; D017346:Protein Serine-Threonine Kinases; C486409:STK39 protein, human; C484754:ULK1 protein, human; D000076204:WNK Lysine-Deficient Protein Kinase 1; C498743:WNK1 protein, human
keywords: PI3KC3; SPAK; ULK1; UVRAG; Vps34