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1.
Gan To Kagaku Ryoho ; 49(1): 63-65, 2022 Jan.
Article in Japanese | MEDLINE | ID: mdl-35046364

ABSTRACT

A man in his 70s was observed to have GIST recurrence 19 months after surgery. Chemotherapy was initiated with imatinib 400 mg/day orally. The dose was eventually reduced to 100 mg/day to avoid side effects. Tumor reduction was confirmed 3 months after treatment initiation. Currently, 84 months after the onset of GIST, the patient survives with continuous intake of the same dose of oral imatinib. We were able to observe long-term survival in a patient with recurrent GIST after the administration of a small dose of imatinib.


Subject(s)
Antineoplastic Agents , Gastrointestinal Stromal Tumors , Antineoplastic Agents/therapeutic use , Benzamides/therapeutic use , Gastrointestinal Stromal Tumors/drug therapy , Gastrointestinal Stromal Tumors/surgery , Humans , Imatinib Mesylate/therapeutic use , Male , Neoplasm Recurrence, Local/drug therapy , Piperazines/therapeutic use , Pyrimidines/therapeutic use
2.
Am J Physiol Renal Physiol ; 318(3): F600-F616, 2020 03 01.
Article in English | MEDLINE | ID: mdl-31904282

ABSTRACT

Prior studies have implicated myosin light chain kinase (MLCK) in the regulation of aquaporin-2 (AQP2) in the renal collecting duct. To discover signaling targets of MLCK, we used CRISPR-Cas9 to delete the MLCK gene (Mylk) to obtain MLCK-null mpkCCD cells and carried out comprehensive phosphoproteomics using stable isotope labeling with amino acids in cell culture for quantification. Immunocytochemistry and electron microscopy demonstrated a defect in the processing of AQP2-containing early endosomes to late endosomes. The phosphoproteomics experiments revealed that, of the 1,743 phosphopeptides quantified over multiple replicates, 107 were changed in abundance by MLCK deletion (29 decreased and 78 increased). One of the decreased phosphopeptides corresponded to the canonical target site in myosin regulatory light chain. Network analysis indicated that targeted phosphoproteins clustered into distinct structural/functional groups: actomyosin, signaling, nuclear envelope, gene transcription, mRNA processing, energy metabolism, intermediate filaments, adherens junctions, and tight junctions. There was significant overlap between the derived MLCK signaling network and a previously determined PKA signaling network. The presence of multiple proteins in the actomyosin category prompted experiments showing that MLCK deletion inhibits the normal effect of vasopressin to depolymerize F-actin, providing a potential explanation for the AQP2 trafficking defect. Changes in phosphorylation of multiple proteins in the nuclear envelope prompted measurement of nuclear size, showing a significant increase in average nuclear volume. We conclude that MLCK is part of a multicomponent signaling pathway in both the cytoplasm and nucleus that includes much more than simple regulation of conventional nonmuscle myosins through myosin regulatory light chain phosphorylation.


Subject(s)
CRISPR-Cas Systems , Myosin-Light-Chain Kinase/metabolism , Proteomics/methods , Animals , Aquaporin 2/genetics , Aquaporin 2/metabolism , Cell Line , Gene Deletion , Gene Expression Regulation , Mice , Mutation , Myosin-Light-Chain Kinase/genetics , Protein Transport
3.
Kidney Int ; 97(4): 713-727, 2020 04.
Article in English | MEDLINE | ID: mdl-32059997

ABSTRACT

The inappropriate over-activation of the with-no-lysine kinase (WNK)-STE20/SPS1-related proline/alanine-rich kinase (SPAK)-sodium chloride cotransporter (NCC) phosphorylation cascade increases sodium reabsorption in distal kidney nephrons, resulting in salt-sensitive hypertension. Although chronic kidney disease (CKD) is a common cause of salt-sensitive hypertension, the involvement of the WNK phosphorylation cascade is unknown. Moreover, the effect of immune systems on WNK kinases has not been investigated despite the fact that immune systems are important for salt sensitivity. Here we demonstrate that the protein abundance of WNK1, but not of WNK4, was increased at the distal convoluted tubules in the aristolochic acid nephropathy mouse model of CKD. Accordingly, the phosphorylation of both SPAK and NCC was also increased. Moreover, a high-salt diet did not adequately suppress activation of the WNK1-SPAK-NCC phosphorylation cascade in this model, leading to salt-sensitive hypertension. WNK1 also was increased in adenine nephropathy, but not in subtotal nephrectomy, models of CKD. By comparing the transcripts of these three models focusing on immune systems, we hypothesized that tumor necrosis factor (TNF)-α regulates WNK1 protein expression. In fact, TNF-α increased WNK1 protein expression in cultured renal tubular cells by reducing the transcription and protein levels of NEDD4-2 E3-ligase, which degrades WNK1 protein. Furthermore, the TNF-α inhibitor etanercept reversed the reduction of NEDD4-2 expression and upregulation of the WNK1-SPAK-NCC phosphorylation cascade in distal convoluted tubules in vivo in the aristolochic acid nephropathy model. Thus, salt-sensitive hypertension is induced in CKD via activation of the renal WNK1- SPAK-NCC phosphorylation cascade by TNF-α, reflecting a link with the immune system.


Subject(s)
Hypertension , Renal Insufficiency, Chronic , Animals , Hypertension/chemically induced , Mice , Phosphorylation , Protein Serine-Threonine Kinases/genetics , Protein Serine-Threonine Kinases/metabolism , Renal Insufficiency, Chronic/chemically induced , Tumor Necrosis Factor-alpha , WNK Lysine-Deficient Protein Kinase 1
4.
Bioorg Med Chem Lett ; 30(17): 127408, 2020 09 01.
Article in English | MEDLINE | ID: mdl-32738993

ABSTRACT

We report here structural development of N-(4-phenoxyphenyl)benzamide derivatives as novel SPAK (STE20/SPS1-related proline/alanine-rich kinase) inhibitors. Abnormal activation of the signal cascade of with-no-lysine kinase (WNK) with OSR1 (oxidative stress-responsive kinase 1)/SPAK and NCC (NaCl cotransporter) results in characteristic salt-sensitive hypertension, and therefore inhibitors of the WNK-OSR1/SPAK-NCC cascade are candidates for antihypertensive drugs. Based on the structure of lead compound 2, we examined the SAR of N-(4-phenoxyphenyl)benzamide derivatives, and developed compound 20l as a potent SPAK inhibitor. Compounds 20l is a promising candidate for a new class of antihypertensive drugs.


Subject(s)
Antihypertensive Agents/chemistry , Benzamides/chemistry , Protein Kinase Inhibitors/pharmacology , Protein Serine-Threonine Kinases/antagonists & inhibitors , Signal Transduction/drug effects , Antihypertensive Agents/metabolism , Antihypertensive Agents/pharmacology , Benzamides/metabolism , Benzamides/pharmacology , Humans , Protein Kinase Inhibitors/chemistry , Protein Kinase Inhibitors/metabolism , Protein Serine-Threonine Kinases/metabolism , Sodium Chloride Symporters/metabolism , Structure-Activity Relationship , WNK Lysine-Deficient Protein Kinase 1/metabolism
5.
Proc Natl Acad Sci U S A ; 114(42): E8875-E8884, 2017 10 17.
Article in English | MEDLINE | ID: mdl-28973931

ABSTRACT

G protein stimulatory α-subunit (Gαs)-coupled heptahelical receptors regulate cell processes largely through activation of protein kinase A (PKA). To identify signaling processes downstream of PKA, we deleted both PKA catalytic subunits using CRISPR-Cas9, followed by a "multiomic" analysis in mouse kidney epithelial cells expressing the Gαs-coupled V2 vasopressin receptor. RNA-seq (sequencing)-based transcriptomics and SILAC (stable isotope labeling of amino acids in cell culture)-based quantitative proteomics revealed a complete loss of expression of the water-channel gene Aqp2 in PKA knockout cells. SILAC-based quantitative phosphoproteomics identified 229 PKA phosphorylation sites. Most of these PKA targets are thus far unannotated in public databases. Surprisingly, 1,915 phosphorylation sites with the motif x-(S/T)-P showed increased phosphooccupancy, pointing to increased activity of one or more MAP kinases in PKA knockout cells. Indeed, phosphorylation changes associated with activation of ERK2 were seen in PKA knockout cells. The ERK2 site is downstream of a direct PKA site in the Rap1GAP, Sipa1l1, that indirectly inhibits Raf1. In addition, a direct PKA site that inhibits the MAP kinase kinase kinase Map3k5 (ASK1) is upstream of JNK1 activation. The datasets were integrated to identify a causal network describing PKA signaling that explains vasopressin-mediated regulation of membrane trafficking and gene transcription. The model predicts that, through PKA activation, vasopressin stimulates AQP2 exocytosis by inhibiting MAP kinase signaling. The model also predicts that, through PKA activation, vasopressin stimulates Aqp2 transcription through induction of nuclear translocation of the acetyltransferase EP300, which increases histone H3K27 acetylation of vasopressin-responsive genes (confirmed by ChIP-seq).


Subject(s)
Epithelial Cells/metabolism , Protein Kinase C/metabolism , Animals , Aquaporin 2/genetics , Aquaporin 2/metabolism , Chromatin Immunoprecipitation , Clustered Regularly Interspaced Short Palindromic Repeats , Cyclic AMP-Dependent Protein Kinase Catalytic Subunits/genetics , E1A-Associated p300 Protein/metabolism , Exocytosis/physiology , GTPase-Activating Proteins/genetics , GTPase-Activating Proteins/metabolism , Gene Knockout Techniques , Kidney/cytology , MAP Kinase Kinase Kinase 5/genetics , MAP Kinase Kinase Kinase 5/metabolism , Mice , Mitogen-Activated Protein Kinase 1/metabolism , Phosphorylation , Protein Kinase C/genetics , Signal Transduction , Vasopressins/metabolism
6.
Kidney Int ; 95(1): 123-137, 2019 01.
Article in English | MEDLINE | ID: mdl-30455054

ABSTRACT

The kidneys consume a large amount of energy to regulate volume status and blood pressure and to excrete uremic toxins. The identification of factors that cause energy mismatch in the setting of chronic kidney disease (CKD) and the development of interventions aimed at improving this mismatch are key research imperatives. Although the critical cellular energy sensor 5'-adenosine monophosphate (AMP)-activated protein kinase (AMPK) is known to be inactivated in CKD, the mechanism of AMPK dysregulation is unknown. In a mouse model of CKD, metabolome analysis confirmed a decrease in AMPK activation in the kidneys despite a high AMP: ATP ratio, suggesting that AMPK did not sense energy depletion. Similar AMPK inactivation was found in heart and skeletal muscle in CKD mice. Several uremic factors were shown to inactivate AMPK in vitro and in ex vivo preparations of kidney tissue. The specific AMPK activator A-769662, which bypasses the AMP sensing mechanism, ameliorated fibrosis and improved energy status in the kidneys of CKD mice, whereas an AMP analog did not. We further demonstrated that a low-protein diet activated AMPK independent of the AMP sensing mechanism, leading to improvement in energy metabolism and kidney fibrosis. These results suggest that a failure to sense AMP is the key mechanism underlying the vicious cycle of energy depletion and CKD progression and direct AMPK activation may be a novel therapeutic approach in CKD.


Subject(s)
AMP-Activated Protein Kinases/metabolism , Diet, Protein-Restricted , Energy Metabolism/physiology , Kidney/pathology , Renal Insufficiency, Chronic/pathology , Adenosine Monophosphate/metabolism , Adenosine Triphosphate/metabolism , Animals , Biphenyl Compounds , Disease Models, Animal , Energy Metabolism/drug effects , Fibrosis/metabolism , Humans , Kidney/metabolism , Male , Metabolomics , Mice , Mice, Inbred C57BL , Muscle, Skeletal/metabolism , Muscle, Skeletal/pathology , Myocardium/metabolism , Myocardium/pathology , Pyrones/pharmacology , Renal Insufficiency, Chronic/diet therapy , Renal Insufficiency, Chronic/etiology , Renal Insufficiency, Chronic/metabolism , Signal Transduction/drug effects , Signal Transduction/physiology , Thiophenes/pharmacology
7.
Biochem Biophys Res Commun ; 517(2): 364-368, 2019 09 17.
Article in English | MEDLINE | ID: mdl-31362893

ABSTRACT

Type 4 Bartter syndrome (BS) is caused by genetic mutations in barttin, which is coded for by BSND. Barttin serves as the ß-subunit of the ClC-K chloride (Cl-) channel, which is widely expressed in distal nephrons. Type 4 BS is characterized by severely impaired reabsorption of salt, which may cause polyuria, hypokalemia, and metabolic alkalosis. Calcineurin inhibitors reportedly induce renal salt retention and hyperkalemia by enhancing the phosphorylation of the sodium (Na+)-potassium (K+)-2Cl- cotransporter (NKCC2) and Na+-Cl- cotransporter (NCC). In addition, we have previously reported that tacrolimus, a calcineurin inhibitor, increases the levels of phosphorylated NCC. In this study, we administered tacrolimus to barttin hypomorphic (Bsndneo/neo) mice, a murine model of type 4 BS that exhibits polyuria, hypokalemia, and metabolic alkalosis. Administration of tacrolimus increased the serum K+ level and suppressed urinary K+ excretion. Furthermore, after treatment with tacrolimus, Bsndneo/neo mice increased levels of phosphorylated NCC and NKCC2. We conclude that tacrolimus partially improves clinical phenotypes of Bsndneo/neo mice, and that calcineurin inhibitors might be effective for treating type 4 BS.


Subject(s)
Bartter Syndrome/drug therapy , Calcineurin Inhibitors/therapeutic use , Hearing Loss, Sensorineural/drug therapy , Sodium-Potassium-Chloride Symporters/agonists , Solute Carrier Family 12, Member 3/agonists , Tacrolimus/therapeutic use , Animals , Bartter Syndrome/metabolism , Disease Models, Animal , Hearing Loss, Sensorineural/metabolism , Hypokalemia/drug therapy , Hypokalemia/metabolism , Mice , Mice, Inbred C57BL , Phosphorylation/drug effects , Sodium-Potassium-Chloride Symporters/metabolism , Solute Carrier Family 12, Member 3/metabolism
8.
Clin Exp Nephrol ; 22(6): 1251-1257, 2018 Dec.
Article in English | MEDLINE | ID: mdl-29869755

ABSTRACT

BACKGROUND: Pseudohypoaldosteronism type II (PHAII) is a hereditary hypertensive disease caused by mutations in four genes: WNK1, WNK4, Kelch-like3 (KLHL3), and cullin3 (CUL3). Recently, it was revealed that CUL3-KLHL3 E3 ligase complex ubiquitinates WNK1 and WNK4, leading to their degradation, and that a common pathogenesis of PHAII is defective WNK degradation due to CUL3-KLHL3 E3 ligase complex impairment. PHAII-causing CUL3 mutations mediate exon9 skipping, producing a CUL3 protein with a 57-amino acid deletion (Δ403-459). However, the pathogenic effects of KLHL3, an adaptor protein that links WNKs with CUL3, in PHAII caused by CUL3 mutation remain unclear. METHODS: To clarify detailed pathophysiological mechanisms underlying PHAII caused by CUL3 mutation in vivo, we generated and analyzed knock-in mice carrying the same CUL3 exon9 deletion (CUL3WT/Δex9) as that reported in PHAII patients. RESULTS: CUL3WT/Δex9 mice exhibited a PHAII-like phenotype. Interestingly, we confirmed markedly decreased KLHL3 expression in CUL3WT/Δex9 mice by confirming the true KLHL3 band in vivo. However, the expression of other KLHL family proteins, such as KLHL2, was comparable between WT and mutant mice. CONCLUSION: KLHL3 expression was decreased in CUL3WT/Δex9 mice. However, expression levels of other KLHL family proteins were comparable between the wild-type and mutant mice. These findings indicate that the decreased abundance of KLHL3 is a specific phenomenon caused by mutant CUL3 (Δexon9). Our findings would improve our understanding of the pathogenesis of PHAII caused by CUL3 mutation in vivo.


Subject(s)
Carrier Proteins/physiology , Cullin Proteins/genetics , Mutation , Pseudohypoaldosteronism/etiology , Adaptor Proteins, Signal Transducing , Animals , Carrier Proteins/analysis , Humans , Mice , Microfilament Proteins , Pseudohypoaldosteronism/genetics
9.
Hum Mol Genet ; 23(19): 5052-60, 2014 Oct 01.
Article in English | MEDLINE | ID: mdl-24821705

ABSTRACT

Pseudohypoaldosteronism type II (PHAII) is a hereditary disease characterized by salt-sensitive hypertension, hyperkalemia and metabolic acidosis, and genes encoding with-no-lysine kinase 1 (WNK1) and WNK4 kinases are known to be responsible. Recently, Kelch-like 3 (KLHL3) and Cullin3, components of KLHL3-Cullin3 E3 ligase, were newly identified as responsible for PHAII. We have reported that WNK4 is the substrate of KLHL3-Cullin3 E3 ligase-mediated ubiquitination. However, WNK1 and Na-Cl cotransporter (NCC) were also reported to be a substrate of KLHL3-Cullin3 E3 ligase by other groups. Therefore, it remains unclear which molecule is the target(s) of KLHL3. To investigate the pathogenesis of PHAII caused by KLHL3 mutation, we generated and analyzed KLHL3(R528H/+) knock-in mice. KLHL3(R528H/+) knock-in mice exhibited salt-sensitive hypertension, hyperkalemia and metabolic acidosis. Moreover, the phosphorylation of NCC was increased in the KLHL3(R528H/+) mouse kidney, indicating that the KLHL3(R528H/+) knock-in mouse is an ideal mouse model of PHAII. Interestingly, the protein expression of both WNK1 and WNK4 was significantly increased in the KLHL3(R528H/+) mouse kidney, confirming that increases in these WNK kinases activated the WNK-OSR1/SPAK-NCC phosphorylation cascade in KLHL3(R528H/+) knock-in mice. To examine whether mutant KLHL3 R528H can interact with WNK kinases, we measured the binding of TAMRA-labeled WNK1 and WNK4 peptides to full-length KLHL3 using fluorescence correlation spectroscopy, and found that neither WNK1 nor WNK4 bound to mutant KLHL3 R528H. Thus, we found that increased protein expression levels of WNK1 and WNK4 kinases cause PHAII by KLHL3 R528H mutation due to impaired KLHL3-Cullin3-mediated ubiquitination.


Subject(s)
Microfilament Proteins/genetics , Mutation , Protein Serine-Threonine Kinases/metabolism , Pseudohypoaldosteronism/genetics , Pseudohypoaldosteronism/metabolism , Adaptor Proteins, Signal Transducing , Animals , Disease Models, Animal , Epithelial Cells/metabolism , Gene Expression , Gene Order , Gene Targeting , Genetic Vectors/genetics , Genotype , Kidney/metabolism , Mice , Mice, Transgenic , Minor Histocompatibility Antigens , Phenotype , Potassium Channels, Inwardly Rectifying/metabolism , Protein Binding , Protein Interaction Domains and Motifs , Protein Serine-Threonine Kinases/genetics , Proteolysis , Sodium Channels/metabolism , Ubiquitination , WNK Lysine-Deficient Protein Kinase 1
10.
J Am Soc Nephrol ; 26(7): 1525-36, 2015 Jul.
Article in English | MEDLINE | ID: mdl-25377078

ABSTRACT

Upon activation by with-no-lysine kinases, STE20/SPS1-related proline-alanine-rich protein kinase (SPAK) phosphorylates and activates SLC12A transporters such as the Na(+)-Cl(-) cotransporter (NCC) and Na(+)-K(+)-2Cl(-) cotransporter type 1 (NKCC1) and type 2 (NKCC2); these transporters have important roles in regulating BP through NaCl reabsorption and vasoconstriction. SPAK knockout mice are viable and display hypotension with decreased activity (phosphorylation) of NCC and NKCC1 in the kidneys and aorta, respectively. Therefore, agents that inhibit SPAK activity could be a new class of antihypertensive drugs with dual actions (i.e., NaCl diuresis and vasodilation). In this study, we developed a new ELISA-based screening system to find novel SPAK inhibitors and screened >20,000 small-molecule compounds. Furthermore, we used a drug repositioning strategy to identify existing drugs that inhibit SPAK activity. As a result, we discovered one small-molecule compound (Stock 1S-14279) and an antiparasitic agent (Closantel) that inhibited SPAK-regulated phosphorylation and activation of NCC and NKCC1 in vitro and in mice. Notably, these compounds had structural similarity and inhibited SPAK in an ATP-insensitive manner. We propose that the two compounds found in this study may have great potential as novel antihypertensive drugs.


Subject(s)
Hypertension/drug therapy , Protein Serine-Threonine Kinases/metabolism , Sodium-Potassium-Chloride Symporters/metabolism , Animals , Antihypertensive Agents/pharmacology , Disease Models, Animal , Enzyme-Linked Immunosorbent Assay , Female , Ion Transport/physiology , Mice , Mice, Inbred C57BL , Minor Histocompatibility Antigens , Phosphorylation/genetics , Protein Serine-Threonine Kinases/drug effects , Protein Serine-Threonine Kinases/genetics , Random Allocation , Salicylanilides/pharmacology , Sensitivity and Specificity , Signal Transduction/genetics , WNK Lysine-Deficient Protein Kinase 1
11.
J Am Soc Nephrol ; 26(9): 2129-38, 2015 Sep.
Article in English | MEDLINE | ID: mdl-25556166

ABSTRACT

Recently, the kelch-like protein 3 (KLHL3)-Cullin3 complex was identified as an E3 ubiquitin ligase for with no lysine (WNK) kinases, and the impaired ubiquitination of WNK4 causes pseudohypoaldosteronism type II (PHAII), a hereditary hypertensive disease. However, the involvement of WNK kinase regulation by ubiquitination in situations other than PHAII has not been identified. Previously, we identified the WNK3-STE20/SPS1-related proline/alanine-rich kinase-Na/K/Cl cotransporter isoform 1 phosphorylation cascade in vascular smooth muscle cells and found that it constitutes an important mechanism of vascular constriction by angiotensin II (AngII). In this study, we investigated the involvement of KLHL proteins in AngII-induced WNK3 activation of vascular smooth muscle cells. In the mouse aorta and mouse vascular smooth muscle (MOVAS) cells, KLHL3 was not expressed, but KLHL2, the closest homolog of KLHL3, was expressed. Salt depletion and acute infusion of AngII decreased KLHL2 and increased WNK3 levels in the mouse aorta. Notably, the AngII-induced changes in KLHL2 and WNK3 expression occurred within minutes in MOVAS cells. Results of KLHL2 overexpression and knockdown experiments in MOVAS cells confirmed that KLHL2 is the major regulator of WNK3 protein abundance. The AngII-induced decrease in KLHL2 was not caused by decreased transcription but increased autophagy-mediated degradation. Furthermore, knockdown of sequestosome 1/p62 prevented the decrease in KLHL2, suggesting that the mechanism of KLHL2 autophagy could be selective autophagy mediated by sequestosome 1/p62. Thus, we identified a novel component of signal transduction in AngII-induced vascular contraction that could be a promising drug target.


Subject(s)
Angiotensin II/pharmacokinetics , Microfilament Proteins/metabolism , Muscle Tonus/physiology , Nerve Tissue Proteins/metabolism , Protein Serine-Threonine Kinases/metabolism , Signal Transduction/drug effects , Adaptor Proteins, Signal Transducing/genetics , Angiotensin II/pharmacology , Animals , Aorta , Autophagy/drug effects , Cells, Cultured , Gene Knockdown Techniques , Heat-Shock Proteins/genetics , Mice , Microfilament Proteins/drug effects , Microfilament Proteins/genetics , Muscle, Smooth, Vascular/metabolism , Myocytes, Smooth Muscle/metabolism , Nerve Tissue Proteins/drug effects , Nerve Tissue Proteins/genetics , Protein Serine-Threonine Kinases/drug effects , Sequestosome-1 Protein , Sodium, Dietary/pharmacology , Solute Carrier Family 12, Member 2/metabolism , Vasoconstriction
12.
Biochem Biophys Res Commun ; 467(2): 229-34, 2015 Nov 13.
Article in English | MEDLINE | ID: mdl-26435498

ABSTRACT

Mutations in with-no-lysine kinase (WNK) 1, WNK4, Kelch-like 3 (KLHL3), and Cullin3 result in an inherited hypertensive disease, pseudohypoaldosteronism type II. WNK activates the Na-Cl cotransporter (NCC), increasing sodium reabsorption in the kidney. Further, KLHL3, an adapter protein of Cullin3-based E3 ubiquitin ligase, has been recently found to bind to WNK, thereby degrading them. Insulin and vasopressin have been identified as powerful activators of WNK signaling. In this study, we investigated effects of Akt and PKA, key downstream substrates of insulin and vasopressin signaling, respectively, on KLHL3. Mass spectrometry analysis revealed that KLHL3 phosphorylation at S433. Phospho-specific antibody demonstrated defective binding between phosphorylated KLHL3 and WNK4. Consistent with the fact that S433 is a component of Akt and PKA phosphorylation motifs, in vitro kinase assay demonstrated that Akt and PKA can phosphorylate KLHL3 at S433, that was previously reported to be phosphorylated by PKC. Further, forskolin, a representative PKA stimulator, increased phosphorylation of KLHL3 at S433 and WNK4 protein expression in HEK293 cells by inhibiting the KLHL3 effect that leads to WNK4 degradation. Insulin also increased phosphorylation of KLHL3 at S433 in cultured cells. In conclusion, we found that Akt and PKA phosphorylated KLHL3 at S433, and phosphorylation of KLHL3 by PKA inhibited WNK4 degradation. This could be a novel mechanism on how insulin and vasopressin physiologically activate the WNK signal.


Subject(s)
Carrier Proteins/genetics , Cyclic AMP-Dependent Protein Kinases/genetics , Protein Serine-Threonine Kinases/genetics , Proto-Oncogene Proteins c-akt/genetics , Adaptor Proteins, Signal Transducing , Amino Acid Sequence , Carrier Proteins/metabolism , Colforsin/pharmacology , Cullin Proteins/genetics , Cullin Proteins/metabolism , Cyclic AMP-Dependent Protein Kinases/metabolism , Gene Expression Regulation , HEK293 Cells , Humans , Insulin/pharmacology , Intracellular Signaling Peptides and Proteins/genetics , Intracellular Signaling Peptides and Proteins/metabolism , Microfilament Proteins , Minor Histocompatibility Antigens , Molecular Sequence Data , Phosphorylation/drug effects , Protein Serine-Threonine Kinases/metabolism , Protein Structure, Tertiary , Proto-Oncogene Proteins c-akt/metabolism , Signal Transduction , Vasopressins/pharmacology , WNK Lysine-Deficient Protein Kinase 1
13.
Kyobu Geka ; 67(2): 165-8, 2014 Feb.
Article in Japanese | MEDLINE | ID: mdl-24743491

ABSTRACT

An 76-year-old man was referred to our hospital due to right hydrothorax. The diffuse thickening of parietal pleura with increased fluoro-2-deoxy-D-glucose (FDG) uptake was noted by computed tomography (CT) and positron emission tomography (PET). Surgical biopsy was performed and the tumor was diagnosed as mucosal associated lymphoid tissue (MALT) lymphomas of parietal pleura origin by pathology. Complete remission was achieved by postoperative chemotherapy (R-CHOP), and the patient is now alive without recurrence.


Subject(s)
Lymphoma, B-Cell, Marginal Zone/pathology , Pleural Neoplasms/pathology , Aged , Humans , Lymphoma, B-Cell, Marginal Zone/diagnosis , Male , Pleural Neoplasms/diagnosis
14.
Am J Physiol Renal Physiol ; 305(9): F1374-81, 2013 Nov 01.
Article in English | MEDLINE | ID: mdl-24026181

ABSTRACT

The Na-Cl cotransporter (NCC) in the distal convoluted tubules in kidney is known to be excreted in urine. However, its clinical significance has not been established because of the lack of quantitative data on urinary NCC. We developed highly sensitive enzyme-linked immunosorbent assays (ELISAs) for urinary total NCC (tNCC) and its active form, phosphorylated NCC (pNCC). We first measured the excretion of tNCC and pT55-NCC in urinary exosomes in pseudohypoaldosteronism type II (PHAII) patients since PHAII is caused by NCC activation. Highly increased excretion of tNCC and pNCC was observed in PHAII patients. In contrast, the levels of tNCC and pNCC in the urine of patients with Gitelman's syndrome were not detectable or very low, indicating that both assays could specifically detect the changes in urinary NCC excretion caused by the changes of NCC activity in the kidney. Then, to test whether these assays could be feasible for a more general patient population, we measured tNCC and pNCC in the urine of outpatients with different clinical backgrounds. Although urinary protein levels >30 mg/dl interfered with our ELISA, we could measure urinary pNCC in all patients without proteinuria. Thus we established highly sensitive and quantitative assays for urinary NCC, which could be valuable tools for estimating NCC activity in vivo.


Subject(s)
Enzyme-Linked Immunosorbent Assay/methods , Solute Carrier Family 12, Member 3/urine , Aged , Animals , Exosomes/chemistry , Female , Gitelman Syndrome/urine , Humans , Male , Mice , Middle Aged , Phosphorylation , Pseudohypoaldosteronism/urine , Sodium Chloride Symporter Inhibitors
15.
Pediatr Nephrol ; 28(9): 1881-4, 2013 Sep.
Article in English | MEDLINE | ID: mdl-23689903

ABSTRACT

BACKGROUND: Four genes responsible for pseudohypoaldosteronism type II (PHA-II) have been identified, thereby facilitating molecular diagnostic testing. CASE-DIAGNOSIS/TREATMENT: A 1-year-old boy with prolonged hyperkalemia, metabolic acidosis, hyperchloremia, growth delay, and mild hypertension was diagnosed with PHA-II based on the detection of exon 9 skipping in CUL3 mRNA. The impaired splicing was the result of a de novo, previously unreported single nucleotide substitution in the splice acceptor site of CUL3 intron 8. Among the four genes reported to be involved in PHA-II, CUL3 was the primary suspect in our patient because in patients with the CUL3 mutation, the onset of disease is often early in infancy and the phenotypes of PHA-II are more severe. Our patient was treated with trichlormethiazide, which inhibits the function of the sodium-chloride co-transporter (NCC), and the outcome was favorable, with correction of body fluids and blood electrolyte homeostasis. CONCLUSION: Since chronic acidosis and hypertension associated with PHA-II can result in delayed growth and development in pediatric patients, genetic analysis to detect the CUL3 mutation and to enable intervention early in the disease course would be beneficial for infants with suspected PHA-II.


Subject(s)
Cullin Proteins/genetics , Pseudohypoaldosteronism/genetics , Acid-Base Imbalance/blood , Acid-Base Imbalance/genetics , Acidosis/etiology , Acidosis/therapy , Bicarbonates/blood , Blood Pressure/physiology , Chlorides/blood , Diuretics/therapeutic use , Exons/genetics , Genetic Testing , Humans , Infant , Introns/genetics , Male , Potassium/blood , Pseudohypoaldosteronism/diagnosis , Pseudohypoaldosteronism/therapy , RNA, Messenger/genetics , Real-Time Polymerase Chain Reaction , Trichlormethiazide/therapeutic use
16.
BMC Nephrol ; 14: 166, 2013 Jul 31.
Article in English | MEDLINE | ID: mdl-23902721

ABSTRACT

BACKGROUND: Pseudohypoaldosteronism type II (PHA II), also referred to as Gordon syndrome, is a rare renal tubular disease that is inherited in an autosomal manner. Though mutations in WNK1 and WNK4 partially account for this disorder, in 2012, 2 research groups showed that KLHL3 and CUL3 were the causative genes for PHA II. Here, we firstly report on the Japanese child of PHA II caused by a mutation of CUL 3. CASE PRESENTATION: The patient was a 3-year-old Japanese girl having healthy unrelated parents. She was initially observed to have hyperkalemia, hyperchloremia, metabolic acidosis, and hypertension. A close investigation led to the diagnosis of PHA II, upon which abnormal findings of laboratory examinations and hypertension were immediately normalized by administering thiazides. Genetic analysis of WNK1 and WNK4 revealed no mutations. However, analysis of the CUL3 gene of the patient showed abnormal splicing caused by the modification of exon 9. The patient is currently 17 years old and does not exhibit hypertension or any abnormal findings on laboratory examination. CONCLUSIONS: In this patient, CUL3 was found to play a fundamental role in the regulation of blood pressure, potassium levels, and acid-base balance.


Subject(s)
Cullin Proteins/genetics , Mutation/genetics , Pseudohypoaldosteronism/diagnosis , Pseudohypoaldosteronism/genetics , Adolescent , Child, Preschool , Female , Humans
17.
Biochem Biophys Res Commun ; 427(4): 743-7, 2012 Nov 02.
Article in English | MEDLINE | ID: mdl-23044422

ABSTRACT

Blood pressure and renal salt excretion show circadian rhythms. Recently, it has been clarified that clock genes regulate circadian rhythms of renal transporter expression in the kidney. Since we discovered the WNK-OSR1/SPAK-NaCl cotransporter (NCC) signal cascade, which is important for regulating salt balance and blood pressure, we have sought to determine whether NCC protein expression or phosphorylation shows diurnal rhythms in the mouse kidneys. Male C57BL/6J mice were sacrificed every 4h (at 20:00, 0:00, 4:00, 8:00, 12:00, and 16:00), and the expression and phosphorylation of WNK4, OSR1, SPAK, and NCC were determined by immunoblot. (Lights were turned on at 8:00, which was the start of the rest period, and turned off at 20:00, which was the start of the active period, since mice are nocturnal.) Although expression levels of each protein did not show diurnal rhythm, the phosphorylation levels of OSR1, SPAK, and NCC were increased around the start of the active period and decreased around the start of the rest period. Oral administration of eplerenone (10mg/day) attenuated the phosphorylation levels of these proteins and also diminished the diurnal rhythm of NCC phosphorylation. Thus, the activity of the WNK4-OSR1/SPAK-NCC cascade was shown to have a diurnal rhythm in the kidney that may be governed by aldosterone.


Subject(s)
Aldosterone/physiology , Circadian Rhythm/physiology , Protein Serine-Threonine Kinases/metabolism , Receptors, Drug/metabolism , Symporters/metabolism , Aldosterone/pharmacology , Animals , Circadian Rhythm/drug effects , Male , Mice , Mice, Inbred C57BL , Phosphorylation , Signal Transduction , Solute Carrier Family 12, Member 3
18.
Biochem Biophys Res Commun ; 425(2): 456-61, 2012 Aug 24.
Article in English | MEDLINE | ID: mdl-22846565

ABSTRACT

Na-Cl cotransporter (NCC) is phosphorylated in its amino terminus based on salt intake under the regulation of the WNK-OSR1/SPAK kinase cascade. We have observed that total protein abundance of NCC and its apical membrane expression varies in the kidney based on the phosphorylation status. To clarify the mechanism, we examined NCC ubiquitination status in mice fed low, normal and high salt diets, as well as in a model mouse of pseudohypoaldosteronism type II (PHAII) where NCC phosphorylation is constitutively elevated. Low-salt diet decreased NCC ubiquitination, while high-salt diet increased NCC ubiquitination in the kidney, and this was inversely correlated with total and phosphorylated NCC abundance. In the PHAII model, the ubiquitination of NCC in kidney was also lower when compared to that in wild-type littermates. To evaluate the relationship between phosphorylation and ubiquitination of NCC, we expressed wild-type, phospho-deficient and -mimicking NCC in COS7 cells, and the ubiquitination of immunoprecipitated total and biotinylated surface NCC was evaluated. NCC ubiquitination was increased in the phospho-deficient NCC and decreased in phospho-mimicking NCC in both total and surface NCC. Thus, we demonstrated that NCC phosphorylation decreased NCC ubiquitination, which may contribute to the increase of NCC abundance mostly on plasma membranes.


Subject(s)
Diet, Sodium-Restricted , Protein Serine-Threonine Kinases/metabolism , Pseudohypoaldosteronism/metabolism , Receptors, Drug/metabolism , Symporters/metabolism , Ubiquitination , Animals , COS Cells , Chlorocebus aethiops , Disease Models, Animal , Mice , Mice, Inbred C57BL , Phosphorylation , Solute Carrier Family 12, Member 3
19.
Phys Chem Chem Phys ; 14(46): 16023-31, 2012 Dec 14.
Article in English | MEDLINE | ID: mdl-23104018

ABSTRACT

A novel oxide-supported Ir dimer, which was found to be active for transfer hydrogenation of aromatic ketones, was prepared on a γ-Al(2)O(3) surface from an Ir dimer complex [Ir(2){η(5)-C(5)(CH(3))(5)}(2)(µ-CH(2))(2)] (Ir(2)) with an Ir=Ir bond. Detailed characterization of the γ-Al(2)O(3)-supported Ir dimer (Ir(2)/γ-Al(2)O(3)) revealed that the structure of Ir(2) consisted of an Ir dimer with an Ir-Ir bond attached to the γ-Al(2)O(3) surface by two bridged Ir-(OAl)(2)-Ir bonds. The supported Ir(2)/γ-Al(2)O(3) dimer with bridged Ir-(OAl)(2)-Ir bonds acted as an efficient catalyst for transfer hydrogenation (turnover number of acetophenone = 699 (24 h)), while homogeneous Ir(2), SiO(2)- and MgO-supported Ir(2) were much less active. A structural transformation at the interface of the Ir dimer and the γ-Al(2)O(3) surface was suggested to assist the transfer hydrogenation catalysis via the formation of an Ir(2)-H(2) species on the γ-Al(2)O(3) surface (Ir(2)-H(2)/γ-Al(2)O(3)) as a key intermediate in the transfer hydrogenation. The present study deepened the understanding of the role and dynamic behaviour of the oxide surface in the hydrogen transfer catalysis on the supported Ir dimer.

20.
Kyobu Geka ; 65(13): 1123-6, 2012 Dec.
Article in Japanese | MEDLINE | ID: mdl-23202706

ABSTRACT

A 77-year-old woman was admitted to our hospital with abnormal chest shadow detected on a medical checkup. Chest computed tomography(CT)showed a well-defined tumor in the upper lobe of the right lung. On positron emission tomography by fluorodeoxyglucose(FDG),the tumor revealed to be positive. We performed right upper lobectomy with hilar and mediastinal lymph node dissection. The histopathological diagnosis was lymphoepithelioma-like carcinoma (LELC). In the past 25-years, 41 cases have been reported in Japan. The average age is 64 years old, including 25 male cases and 16 female cases. Among these cases, more than half were in the early resectable stage.


Subject(s)
Carcinoma, Large Cell/diagnosis , Lung Neoplasms/diagnosis , Aged , Carcinoma, Large Cell/pathology , Female , Humans , Lung Neoplasms/pathology
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