1
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den Uil SH, Coupé VMH, Linnekamp JF, van den Broek E, Goos JACM, Delis-van Diemen PM, Belt EJT, van Grieken NCT, Scott PM, Vermeulen L, Medema JP, Bril H, Stockmann HBAC, Cormier RT, Meijer GA, Fijneman RJA. Loss of KCNQ1 expression in stage II and stage III colon cancer is a strong prognostic factor for disease recurrence. Br J Cancer 2016; 115:1565-1574. [PMID: 27855440 PMCID: PMC5155368 DOI: 10.1038/bjc.2016.376] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2016] [Revised: 09/29/2016] [Accepted: 10/17/2016] [Indexed: 01/04/2023] Open
Abstract
Background: Colorectal cancer (CRC) is the third most common cancer worldwide. Accurately identifying stage II CRC patients at risk for recurrence is an unmet clinical need. KCNQ1 was previously identified as a tumour suppressor gene and loss of expression was associated with poor survival in patients with CRC liver metastases. In this study the prognostic value of KCNQ1 in stage II and stage III colon cancer patients was examined. Methods: KCNQ1 mRNA expression was assessed in 90 stage II colon cancer patients (AMC-AJCCII-90) using microarray gene expression data. Subsequently, KCNQ1 protein expression was evaluated in an independent cohort of 386 stage II and stage III colon cancer patients by immunohistochemistry of tissue microarrays. Results: Low KCNQ1 mRNA expression in stage II microsatellite stable (MSS) colon cancers was associated with poor disease-free survival (DFS) (P=0.025). Loss of KCNQ1 protein expression from epithelial cells was strongly associated with poor DFS in stage II MSS (P<0.0001), stage III MSS (P=0.0001) and stage III microsatellite instable colon cancers (P=0.041). KCNQ1 seemed an independent prognostic value in addition to other high-risk parameters like angio-invasion, nodal stage and microsatellite instability-status. Conclusions: We conclude that KCNQ1 is a promising biomarker for prediction of disease recurrence and may aid stratification of patients with stage II MSS colon cancer for adjuvant chemotherapy.
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Affiliation(s)
- Sjoerd H den Uil
- Department of Pathology, VU University Medical Center, Amsterdam 1081HV, The Netherlands.,Department of Surgery, Spaarne Gasthuis, Haarlem 2035RC, The Netherlands
| | - Veerle M H Coupé
- Department of Epidemiology and Biostatistics, VU University Medical Center, Amsterdam 1081HV, The Netherlands
| | - Janneke F Linnekamp
- Laboratory of Experimental Oncology and Radiobiology, Center for Experimental Molecular Medicine, Academic Medical Center, Amsterdam 1100DD, The Netherlands
| | - Evert van den Broek
- Department of Pathology, VU University Medical Center, Amsterdam 1081HV, The Netherlands.,Department of Pathology, The Netherlands Cancer Institute, Amsterdam 1066CX, The Netherlands
| | - Jeroen A C M Goos
- Department of Pathology, VU University Medical Center, Amsterdam 1081HV, The Netherlands
| | - Pien M Delis-van Diemen
- Department of Pathology, VU University Medical Center, Amsterdam 1081HV, The Netherlands.,Department of Pathology, The Netherlands Cancer Institute, Amsterdam 1066CX, The Netherlands
| | - Eric J Th Belt
- Department of Surgery, Albert Schweitzer Hospital, Dordrecht 3300AK, The Netherlands
| | - Nicole C T van Grieken
- Department of Pathology, VU University Medical Center, Amsterdam 1081HV, The Netherlands
| | - Patricia M Scott
- Department of Biomedical Sciences, University of Minnesota Medical School, Duluth, Minnesota, MN 55812, USA
| | - Louis Vermeulen
- Laboratory of Experimental Oncology and Radiobiology, Center for Experimental Molecular Medicine, Academic Medical Center, Amsterdam 1100DD, The Netherlands
| | - Jan Paul Medema
- Laboratory of Experimental Oncology and Radiobiology, Center for Experimental Molecular Medicine, Academic Medical Center, Amsterdam 1100DD, The Netherlands
| | - Herman Bril
- Department of Pathology, Spaarne Gasthuis, Haarlem 2035RC, The Netherlands
| | | | - Robert T Cormier
- Department of Biomedical Sciences, University of Minnesota Medical School, Duluth, Minnesota, MN 55812, USA
| | - Gerrit A Meijer
- Department of Pathology, VU University Medical Center, Amsterdam 1081HV, The Netherlands.,Department of Pathology, The Netherlands Cancer Institute, Amsterdam 1066CX, The Netherlands
| | - Remond J A Fijneman
- Department of Pathology, VU University Medical Center, Amsterdam 1081HV, The Netherlands.,Department of Pathology, The Netherlands Cancer Institute, Amsterdam 1066CX, The Netherlands
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2
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Andersen MN, Krzystanek K, Petersen F, Bomholtz SH, Olesen SP, Abriel H, Jespersen T, Rasmussen HB. A phosphoinositide 3-kinase (PI3K)-serum- and glucocorticoid-inducible kinase 1 (SGK1) pathway promotes Kv7.1 channel surface expression by inhibiting Nedd4-2 protein. J Biol Chem 2013; 288:36841-54. [PMID: 24214981 DOI: 10.1074/jbc.m113.525931] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Epithelial cell polarization involves several kinase signaling cascades that eventually divide the surface membrane into an apical and a basolateral part. One kinase, which is activated during the polarization process, is phosphoinositide 3-kinase (PI3K). In MDCK cells, the basolateral potassium channel Kv7.1 requires PI3K activity for surface-expression during the polarization process. Here, we demonstrate that Kv7.1 surface expression requires tonic PI3K activity as PI3K inhibition triggers endocytosis of these channels in polarized MDCK. Pharmacological inhibition of SGK1 gave similar results as PI3K inhibition, whereas overexpression of constitutively active SGK1 overruled it, suggesting that SGK1 is the primary downstream target of PI3K in this process. Furthermore, knockdown of the ubiquitin ligase Nedd4-2 overruled PI3K inhibition, whereas a Nedd4-2 interaction-deficient Kv7.1 mutant was resistant to both PI3K and SGK1 inhibition. Altogether, these data suggest that a PI3K-SGK1 pathway stabilizes Kv7.1 surface expression by inhibiting Nedd4-2-dependent endocytosis and thereby demonstrates that Nedd4-2 is a key regulator of Kv7.1 localization and turnover in epithelial cells.
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Affiliation(s)
- Martin Nybo Andersen
- From The Danish National Research Foundation Centre for Cardiac Arrhythmia, Department of Biomedical Sciences, University of Copenhagen, Blegdamsvej 3, 2200 Copenhagen N, Denmark and
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3
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Lang F, Shumilina E. Regulation of ion channels by the serum- and glucocorticoid-inducible kinase SGK1. FASEB J 2012; 27:3-12. [PMID: 23012321 DOI: 10.1096/fj.12-218230] [Citation(s) in RCA: 126] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
The ubiquitously expressed serum- and glucocorticoid-inducible kinase-1 (SGK1) is genomically regulated by cell stress (including cell shrinkage) and several hormones (including gluco- and mineralocorticoids). SGK1 is activated by insulin and growth factors through PI3K and 3-phosphoinositide-dependent kinase PDK1. SGK1 activates a wide variety of ion channels (e.g., ENaC, SCN5A, TRPV4-6, ROMK, Kv1.3, Kv1.5, Kv4.3, KCNE1/KCNQ1, KCNQ4, ASIC1, GluR6, ClCKa/barttin, ClC2, CFTR, and Orai/STIM), which participate in the regulation of transport, hormone release, neuroexcitability, inflammation, cell proliferation, and apoptosis. SGK1-sensitive ion channels participate in the regulation of renal Na(+) retention and K(+) elimination, blood pressure, gastric acid secretion, cardiac action potential, hemostasis, and neuroexcitability. A common (∼3-5% prevalence in Caucasians and ∼10% in Africans) SGK1 gene variant is associated with increased blood pressure and body weight as well as increased prevalence of type II diabetes and stroke. SGK1 further contributes to the pathophysiology of allergy, peptic ulcer, fibrosing disease, ischemia, tumor growth, and neurodegeneration. The effect of SGK1 on channel activity is modest, and the channels do not require SGK1 for basic function. SGK1-dependent ion channel regulation may thus become pathophysiologically relevant primarily after excessive (pathological) expression. Therefore, SGK1 may be considered an attractive therapeutic target despite its broad range of functions.
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Affiliation(s)
- Florian Lang
- Department of Physiology, University of Tuebingen, Gmelinstrasse 5, 72076 Tuebingen, Germany.
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4
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Qadri SM, Mahmud H, Lang E, Gu S, Bobbala D, Zelenak C, Jilani K, Siegfried A, Föller M, Lang F. Enhanced suicidal erythrocyte death in mice carrying a loss-of-function mutation of the adenomatous polyposis coli gene. J Cell Mol Med 2012; 16:1085-93. [PMID: 21781276 PMCID: PMC4365887 DOI: 10.1111/j.1582-4934.2011.01387.x] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
Loss-of-function mutations in human adenomatous polyposis coli (APC) lead to multiple colonic adenomatous polyps eventually resulting in colonic carcinoma. Similarly, heterozygous mice carrying defective APC (apcMin/+) suffer from intestinal tumours. The animals further suffer from anaemia, which in theory could result from accelerated eryptosis, a suicidal erythrocyte death triggered by enhanced cytosolic Ca2+ activity and characterized by cell membrane scrambling and cell shrinkage. To explore, whether APC-deficiency enhances eryptosis, we estimated cell membrane scrambling from annexin V binding, cell size from forward scatter and cytosolic ATP utilizing luciferin–luciferase in isolated erythrocytes from apcMin/+ mice and wild-type mice (apc+/+). Clearance of circulating erythrocytes was estimated by carboxyfluorescein-diacetate-succinimidyl-ester labelling. As a result, apcMin/+ mice were anaemic despite reticulocytosis. Cytosolic ATP was significantly lower and annexin V binding significantly higher in apcMin/+ erythrocytes than in apc+/+ erythrocytes. Glucose depletion enhanced annexin V binding, an effect significantly more pronounced in apcMin/+ erythrocytes than in apc+/+ erythrocytes. Extracellular Ca2+ removal or inhibition of Ca2+ entry with amiloride (1 mM) blunted the increase but did not abrogate the genotype differences of annexin V binding following glucose depletion. Stimulation of Ca2+-entry by treatment with Ca2+-ionophore ionomycin (10 μM) increased annexin V binding, an effect again significantly more pronounced in apcMin/+ erythrocytes than in apc+/+ erythrocytes. Following retrieval and injection into the circulation of the same mice, apcMin/+ erythrocytes were more rapidly cleared from circulating blood than apc+/+ erythrocytes. Most labelled erythrocytes were trapped in the spleen, which was significantly enlarged in apcMin/+ mice. The observations point to accelerated eryptosis and subsequent clearance of apcMin/+ erythrocytes, which contributes to or even accounts for the enhanced erythrocyte turnover, anaemia and splenomegaly in those mice.
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Affiliation(s)
- Syed M Qadri
- Department of Physiology, University of Tübingen, Tübingen, Germany
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5
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Schmidt EM, Gu S, Anagnostopoulou V, Alevizopoulos K, Föller M, Lang F, Stournaras C. Serum- and glucocorticoid-dependent kinase-1-induced cell migration is dependent on vinculin and regulated by the membrane androgen receptor. FEBS J 2012; 279:1231-42. [DOI: 10.1111/j.1742-4658.2012.08515.x] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
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6
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Sgk1 sensitivity of Na(+)/H(+) exchanger activity and cardiac remodeling following pressure overload. Basic Res Cardiol 2012; 107:236. [PMID: 22212557 DOI: 10.1007/s00395-011-0236-2] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/19/2011] [Revised: 11/15/2011] [Accepted: 12/04/2011] [Indexed: 01/08/2023]
Abstract
Sustained increase of cardiac workload is known to trigger cardiac remodeling with eventual development of cardiac failure. Compelling evidence points to a critical role of enhanced cardiac Na(+)/H(+) exchanger (NHE1) activity in the underlying pathophysiology. The signaling triggering up-regulation of NHE1 remained, however, ill defined. The present study explored the involvement of the serum- and glucocorticoid-inducible kinase Sgk1 in cardiac remodeling due to transverse aortic constriction (TAC). To this end, experiments were performed in gene targeted mice lacking functional Sgk1 (sgk1 (-/-)) and their wild-type controls (sgk1 (+/+)). Transcript levels have been determined by RT-PCR, cytosolic pH (pH( i )) utilizing 2',7'-bis-(2-carboxyethyl)-5-(and-6)-carboxyfluorescein (BCECF) fluorescence, Na(+)/H(+) exchanger activity by the Na(+)-dependent realkalinization after an ammonium pulse, ejection fraction (%) utilizing cardiac cine magnetic resonance imaging and cardiac glucose uptake by PET imaging. As a result, TAC increased the mRNA expression of Sgk1 in sgk1 (+/+) mice, paralleled by an increase in Nhe1 transcript levels as well as Na(+)/H(+) exchanger activity, all effects virtually abrogated in sgk1 (-/-) mice. In sgk1 (+/+) mice, TAC induced a decrease in Pgc1a mRNA expression, while Spp1 mRNA expression was increased, both effects diminished in the sgk1 (-/-) mice. TAC was followed by a significant increase of heart and lung weight in sgk1 (+/+) mice, an effect significantly blunted in sgk1 (-/-) mice. TAC increased the transcript levels of Anp and Bnp, effects again significantly blunted in sgk1 (-/-) mice. TAC increased transcript levels of Collagen I and III as well as Ctgf mRNA and CTGF protein abundance, effects significantly blunted in sgk1 (-/-) mice. TAC further decreased the ejection fraction in sgk1 (+/+) mice, an effect again attenuated in sgk1 (-/-) mice. Also, cardiac FDG-glucose uptake was increased to a larger extent in sgk1 (+/+) mice than in sgk1 (-/-) mice after TAC. These observations point to an important role for SGK1 in cardiac remodeling and development of heart failure following an excessive work load.
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7
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Serum- and glucocorticoid-inducible kinase 1 in the regulation of renal and extrarenal potassium transport. Clin Exp Nephrol 2011; 16:73-80. [DOI: 10.1007/s10157-011-0488-z] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2009] [Accepted: 04/08/2010] [Indexed: 01/24/2023]
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8
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Regulation of Na+/H+ exchanger in dendritic cells by Akt2. Pflugers Arch 2011; 463:355-63. [DOI: 10.1007/s00424-011-1015-5] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2011] [Revised: 08/10/2011] [Accepted: 08/11/2011] [Indexed: 12/27/2022]
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9
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Rotte A, Pasham V, Mack AF, Bhandaru M, Qadri SM, Eichenmüller M, Ruth P, Lang F. Ca2+ activated K+ channel Kca3.1 as a determinant of gastric acid secretion. Cell Physiol Biochem 2011; 27:597-604. [PMID: 21691077 DOI: 10.1159/000329981] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/28/2011] [Indexed: 12/28/2022] Open
Abstract
The Ca(2+) activated K(+) channel K(ca)3.1 is expressed in a variety of tissues. In the gastric gland it is expressed in the basolateral cell membrane. To determine the functional significance of K(ca)3.1 activity for gastric acid secretion, gastric acid secretion was determined in isolated glands from gene targeted mice lacking functional K(ca)3.1 (K(ca)3.1(-/-)) and from their wild type littermates (K(ca)3.1(+/+)). According to BCECF-fluorescence cytosolic pH in isolated gastric glands was similar in K(ca)3.1(-/-) and K(ca)3.1(+/+) mice. Na(ca)-independent pH recovery (ΔpH/min) following an ammonium pulse, a measure of H(ca)/K(ca) ATPase activity, was, however, significantly faster in K(ca)3.1(-/-) than in K(ca)3.1(+/+) mice. Accordingly, the luminal pH was significantly lower and the acid content significantly higher in K(ca)3.1(-/-) than in K(ca)3.1(+/+) mice. The abundance of mRNA encoding H(ca)/K(ca) ATPase and KCNQ1 was similar in both genotypes. Increase of extracellular K(ca) concentrations to 35 mM (replacing Na(ca)/NMDG) and treatment with histamine (100 μM) significantly increased ΔpH/min to a larger extent in K(ca)3.1(+/+) than in K(ca)3.1(-/-) mice and dissipated the differences between the genotypes. Carbachol (100 μM) increased ΔpH/min in both genotypes but did not abolish the difference between K(ca)3.1(-/-) and K(ca)3.1(+/+) mice. In K(ca)3.1(+/+) mice the K(ca)3.1 opener DCEBIO (100 μM) did not significantly alter basal ΔpH/min but significantly blunted ΔpH/min in the presence of carbachol. In conclusion, K(ca)3.1 activity suppresses carbachol stimulated gastric acid secretion.
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Affiliation(s)
- Anand Rotte
- Department of Physiology, University of Tübingen, Gmelinstrasse 5, Tübingen, Germany
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10
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Tumor suppressor gene adenomatous polyposis coli downregulates intestinal transport. Pflugers Arch 2011; 461:527-36. [DOI: 10.1007/s00424-011-0945-2] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2010] [Revised: 02/15/2011] [Accepted: 02/16/2011] [Indexed: 12/21/2022]
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11
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Eylenstein A, Gehring EM, Heise N, Shumilina E, Schmidt S, Szteyn K, Münzer P, Nurbaeva MK, Eichenmüller M, Tyan L, Regel I, Föller M, Kuhl D, Soboloff J, Penner R, Lang F. Stimulation of Ca2+-channel Orai1/STIM1 by serum- and glucocorticoid-inducible kinase 1 (SGK1). FASEB J 2011; 25:2012-21. [PMID: 21385992 DOI: 10.1096/fj.10-178210] [Citation(s) in RCA: 68] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Ca(2+) signaling includes store-operated Ca(2+) entry (SOCE) following depletion of endoplasmic reticulum (ER) Ca(2+) stores. On store depletion, the ER Ca(2+) sensor STIM1 activates Orai1, the pore-forming unit of Ca(2+)-release-activated Ca(2+) (CRAC) channels. Here, we show that Orai1 is regulated by serum- and glucocorticoid-inducible kinase 1 (SGK1), a growth factor-regulated kinase. Membrane Orai1 protein abundance, I(CRAC), and SOCE in human embryonic kidney (HEK293) cells stably expressing Orai1 and transfected with STIM1 were each significantly enhanced by coexpression of constitutively active (S422D)SGK1 (by+81, +378, and+136%, respectively) but not by inactive (K127N)SGK1. Coexpression of the ubiquitin ligase Nedd4-2, an established negatively regulated SGK1 target, down-regulated SOCE (by -48%) and I(CRAC) (by -60%), an effect reversed by expression of (S422D)SGK1 (by +175 and +173%, respectively). Orai1 protein abundance and SOCE were significantly lower in mast cells from SGK1-knockout (sgk1(-/-)) mice (by -37% and -52%, respectively) than in mast cells from wild-type (sgk1(+/+)) littermates. Activation of SOCE by sarcoplasmic/endoplasmic reticulum Ca(2+)-ATPase-inhibitor thapsigargin (2 μM) stimulated migration, an effect significantly higher (by +306%) in (S422D)SGK1-expressing than in (K127N)SGK1-expressing HEK293 cells, and also significantly higher (by +108%) in sgk1(+/+) than in sgk1(-/-) mast cells. SGK1 is thus a novel key player in the regulation of SOCE.
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Affiliation(s)
- Anja Eylenstein
- Department of Physiology, University of Tübingen, Gmelinstr. 5, D-72076 Tübingen, Germany
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12
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Pasham V, Rotte A, Bhandaru M, Eichenmüller M, Bobbala D, Yang W, Pearce D, Lang F, Pearce D, Lang F. Regulation of gastric acid secretion by the serum and glucocorticoid inducible kinase isoform SGK3. J Gastroenterol 2011; 46:305-17. [PMID: 21113728 PMCID: PMC6049078 DOI: 10.1007/s00535-010-0348-8] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/20/2010] [Accepted: 10/26/2010] [Indexed: 02/04/2023]
Abstract
BACKGROUND The serum and glucocorticoid inducible kinase isoform SGK3 is ubiquitously expressed and has been shown to participate in the regulation of cell survival and transport. Similar to SGK1 and protein kinase B (PKB/Akt) isoforms, SGK3 may phosphorylate glycogen synthase kinase (GSK) 3α,β, which has recently been shown to participate in the regulation of basal gastric acid secretion. The present study thus explored the role of SGK3 in the regulation of gastric acid secretion. METHODS Experiments were performed in isolated glands from gene-targeted mice lacking functional SGK3 (sgk3-/-) or from their wild-type littermates (sgk3+/+). Utilizing 2',7'-bis-(2-carboxyethyl)-5-(and-6)-carboxyfluorescein, acetoxymethyl ester (BCECF) fluorescence, gastric acid secretion was determined from Na(+)-independent pH recovery (∆pH/min) following an ammonium pulse, which reflects H+/K+ adenosine triphosphatase (ATP) ase activity. RESULTS Cytosolic pH in isolated gastric glands was similar in sgk3-/- and sgk3+/+ mice. ∆pH/min was, however, significantly larger in sgk3-/- than in sgk3+/+ mice. In both genotypes, ∆pH/min was virtually abolished in the presence of the H(+)/K(+) ATPase inhibitor omeprazole (100 μM) and SCH28080 (500 nM). Increase of extracellular K+ concentrations to 35 mM (replacing Na+/NMDG) or treatment with 5 μM forskolin increased ∆pH/min in sgk3+/+ mice to a larger extent than in sgk3-/- mice and abrogated the differences between genotypes. The protein kinase A inhibitor H89 (150 nM) decreased ∆pH/min to similarly low values in both genotypes. CONCLUSIONS SGK3 suppresses gastric acid secretion, an effect presumably mediated by the stimulation of protein kinase A with the subsequent activation of K+ channels.
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Affiliation(s)
| | - Anand Rotte
- Department of Physiology, University of Tübingen, Germany
| | | | | | | | - Wenting Yang
- Department of Physiology, University of Tübingen, Germany
| | - David Pearce
- Department of Medicine (Nephrology), University of California, San Francisco, CA 94122, USA
| | - Florian Lang
- Department of Physiology, University of Tübingen, Germany
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13
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Colorectal carcinoma cells--regulation of survival and growth by SGK1. Int J Biochem Cell Biol 2010; 42:1571-5. [PMID: 20541034 DOI: 10.1016/j.biocel.2010.05.016] [Citation(s) in RCA: 60] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2010] [Revised: 05/28/2010] [Accepted: 05/30/2010] [Indexed: 12/21/2022]
Abstract
Colorectal carcinoma is among the most common malignancies. The tumour cells may arise from mutations in genes encoding proteins involved in the regulation of cell survival and proliferation. Recent evidence disclosed the sensitivity of colon carcinoma to the expression of ubiquitous serum and glucocorticoid inducible kinase-1 (SGK1). The kinase is activated by insulin and growth factors via the phosphatidylinositide-3-kinase (PI3K) and the 3-phosphoinositide dependent kinase (PDK1). SGK1 regulates channels, carriers and Na(+)/K(+)-ATPase, enzymes such as glycogen-synthase-kinase-3 (GSK3) and ubiquitin-ligase Nedd4-2, as well as several transcription factors. SGK1 regulates transport, hormone release, neuroexcitability, inflammation, cell proliferation and apoptosis. SGK1 contributes to metabolic syndrome and the pathophysiology of neurodegeneration, allergy, peptic ulcer, fibrosing disease and response to ischemia. SGK1 is upregulated in some tumours but downregulated in others. SGK1-sensitive mechanisms fostering tumour growth include activation of K(+) channels and Ca(2+) channels, Na(+)/H(+) exchanger, amino acid transporters and glucose transporters, upregulation of the nuclear factor NFkappaB and beta-catenin as well as downregulation of the transcription factors Foxo3a/FKHRL1 and p53. SGK1 enhances survival, invasiveness, motility, epithelial to mesenchymal transition and adhesiveness of tumour cells. Following deficiency of APC (adenoma polyposis coli) or chemical cancerogenesis, SGK1 knockout mice develop less intestinal tumours than their wild-type littermates and pharmacological SGK1 inhibition counteracts growth of prostate cancer cells.
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Potier M, Tran TA, Chantome A, Girault A, Joulin V, Bougnoux P, Vandier C, Pierre F. Altered SK3/KCa2.3-mediated migration in adenomatous polyposis coli (Apc) mutated mouse colon epithelial cells. Biochem Biophys Res Commun 2010; 397:42-7. [PMID: 20519134 DOI: 10.1016/j.bbrc.2010.05.046] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2010] [Accepted: 05/10/2010] [Indexed: 10/19/2022]
Abstract
Lost of adenomatous polyposis coli gene (Apc) disturbs the migration of intestinal epithelial cells but the mechanisms have not been fully characterized. Since we have demonstrated that SK3/KCa2.3 channel promotes cancer cell migration, we hypothesized that Apc mutation may affect SK3/KCa2.3 channel-mediated colon epithelial cell motility. We report evidence that SK3/KCa2.3 channel promotes colon epithelial cells motility. Following Apc mutation SK3/KCa2.3 expression is largely reduced leading to a suppression of the SK3/KCa2.3 channel mediated-cell migration. Our findings reveal a previously unknown function of the SK3/KCa2.3 channel in epithelial colonic cells, and suggest that Apc is a powerful regulator SK3/KCa2.3 channel.
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Affiliation(s)
- Marie Potier
- INSERM U921, Nutrition Croissance et Cancer, 10 Boulevard Tonnelle, Tours Cedex, France
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15
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Rotte A, Pasham V, Bhandaru M, Eichenmüller M, Yang W, Qadri SM, Kempe DS, Puchchakayala G, Pearce D, Birnbaum MJ, Lang F. Regulation of gastric acid secretion by PKB/Akt2. Cell Physiol Biochem 2010; 25:695-704. [PMID: 20511715 DOI: 10.1159/000315089] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/08/2010] [Indexed: 12/16/2022] Open
Abstract
Pharmacological inhibition of phosphoinositol 3 kinase (PI3K) and partial deficiency of phosphoinositide dependent kinase PDK1 have previously been shown to enhance basal gastric acid secretion. PI3K/PDK1 dependent signaling involves activation of protein kinase B/Akt, which may thus be similarly involved in the regulation of gastric acid secretion. To test that hypothesis, gastric acid secretion was determined in isolated glands from gene targeted mice lacking functional Akt2 (akt2(-/-)) or from their wild type littermates (akt2(+/+)). According to BCECF-fluorescence cytosolic pH in isolated gastric glands was similar in akt2(-/-) and akt2(+/+) mice. Na(+)-independent pH recovery (DeltapH/min) following an ammonium pulse, a measure of H(+)/K(+) ATPase activity, was, however, significantly faster in akt2(-/-) than in akt2(+/+) mice. In both genotypes, DeltapH/min was virtually abolished by H(+)/K(+) ATPase inhibitor omeprazole (100 muM). Increase of extracellular K(+) concentrations to 35 mM (replacing Na(+)) increased DeltapH/min to a significantly larger extent in akt2(+/+) than in akt2(-/-) mice and dissipated the differences between the genotypes. Similarly, treatment with 5 muM forskolin enhanced DeltapH/min significantly only in akt2(+/+) mice and abolished the differences between the genotypes. Conversely, protein kinase A inhibitor H89 (50 nM) decreased DeltapH/min to similarly low values in both genotypes. In conclusion, Akt2 suppresses gastric acid secretion and contributes to or even accounts for the inhibition of gastric acid secretion by PI3K.
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Affiliation(s)
- Anand Rotte
- Department of Physiology, University of Tübingen, D-72076 Tübingen, Germany
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Sopjani M, Kunert A, Czarkowski K, Klaus F, Laufer J, Föller M, Lang F. Regulation of the Ca2+ Channel TRPV6 by the Kinases SGK1, PKB/Akt, and PIKfyve. J Membr Biol 2009; 233:35-41. [DOI: 10.1007/s00232-009-9222-0] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2009] [Accepted: 12/02/2009] [Indexed: 12/29/2022]
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Abstract
Compelling evidence is accumulating indicating a pathophysiological role of the serum-and-glucocorticoid-inducible-kinase-1 (SGK1) in the development and complications of diabetes. SGK1 is ubiquitously expressed with exquisitely high transcriptional volatility. Stimulators of SGK1 expression include hyperglycemia, cell shrinkage, ischemia, glucocorticoids and mineralocorticoids. SGK1 is activated by insulin and growth factors via PI3K, 3-phosphoinositide dependent kinase PDK1 and mTOR. SGK1 activates ion channels (including ENaC, TRPV5, ROMK, KCNE1/KCNQ1 and CLCKa/Barttin), carriers (including NCC, NKCC, NHE3, SGLT1 and EAAT3), and the Na(+)/K(+)-ATPase. It regulates the activity of several enzymes (e.g., glycogen-synthase-kinase-3, ubiquitin-ligase Nedd4-2, phosphomannose-mutase-2), and transcription factors (e.g., forkhead-transcription-factor FOXO3a, beta-catenin and NF-kappaB). A common SGK1 gene variant ( approximately 3 - 5% prevalence in Caucasians, approximately 10% in Africans) is associated with increased blood pressure, obesity and type 2 diabetes. In patients suffering from type 2 diabetes, SGK1 presumably contributes to fluid retention and hypertension, enhanced coagulation and increased deposition of matrix proteins leading to tissue fibrosis such as diabetic nephropathy. Accordingly, targeting SGK1 may favourably influence occurrence and course of type 2 diabetes.
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Affiliation(s)
- Florian Lang
- Eberhard-Karls-University of Tuebingen, Department of Physiology, Gmelinstrasse 5, Tuebingen 72076, Germany.
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Lang F, Görlach A. Heterocyclic indazole derivatives as SGK1 inhibitors, WO2008138448. Expert Opin Ther Pat 2009; 20:129-35. [DOI: 10.1517/13543770903365209] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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Abstract
PURPOSE OF REVIEW This review summarizes the last year's literature regarding the regulation and measurement of gastric exocrine and endocrine secretion. RECENT FINDINGS Parietal cells, distributed along much of the length of the oxyntic glands, with highest density in the neck and base, secrete HCl as well as transforming growth factor-alpha, amphiregulin, heparin-binding epidermal growth factor-like growth factor, and sonic hedgehog. Acid facilitates the digestion of protein and absorption of iron, calcium, vitamin B(12) as well as prevents bacterial overgrowth, enteric infection, and possibly food allergy. The major stimulants of acid secretion are gastrin, histamine, and acetylcholine. Ghrelin and orexin also stimulate acid secretion. The main inhibitor of acid secretion is somatostatin. Nitric oxide and dopamine also inhibit acid secretion. Although Helicobacter pylori is associated with duodenal ulcer disease, most patients infected with the organism produce less than normal amount of acid. The cytoskeletal proteins ezrin and moesin participate in parietal cell acid and chief cell pepsinogen secretion, respectively. SUMMARY Despite our vast knowledge, the understanding of the regulation of gastric acid secretion in health and disease is far from complete. A better understanding of the pathways and mechanisms regulating acid secretion should lead to improved management of patients with acid-induced disorders as well as those who secrete too little acid.
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Bhandaru M, Kempe DS, Rotte A, Rexhepaj R, Kuhl D, Lang F. Hyperaldosteronism, hypervolemia, and increased blood pressure in mice expressing defective APC. Am J Physiol Regul Integr Comp Physiol 2009; 297:R571-5. [DOI: 10.1152/ajpregu.00070.2009] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Adenomatous polyposis coli (APC) fosters degradation of β-catenin, a multifunctional protein upregulating the serum- and glucocorticoid-inducible kinase (SGK1). SGK1 regulates a wide variety of renal transport processes. The present study explored the possibility that APC influences renal function. To this end, metabolic cage experiments were performed in mice carrying a loss-of-function mutation in the APC gene ( apc Min/+), their wild-type littermates ( apc+/+), and apc Min/+ mice lacking functional SGK1 ( apc Min/+ /sgk1−/−). As a result, mean body weight, food intake, fluid intake, salt appetite, urinary flow, as well as plasma Na+ and K+ concentrations were similar in apc Min/+ mice, apc+/+ mice, and apc Min/+ /sgk1−/− mice. Glomerular filtration rate and absolute renal Na+ excretion were decreased, and fractional urinary K+ excretion was enhanced in apc Min/+ mice. The antinatriuresis, but not the hypofiltration and kaliuresis was partially reversed by additional lack of SGK1. Plasma corticosterone and aldosterone concentrations were significantly enhanced in apc Min/+ mice. While the plasma corticosterone concentration was similar in apc+/+ mice and apc Min/+ /sgk1−/− mice, plasma aldosterone was even higher in apc Min/+ /sgk1−/− mice than in apc Min/+ mice. The hyperaldosteronism of apc Min/+ mice was paralleled by significantly elevated plasma volume and blood pressure. The experiments reveal an influence of defective APC on adrenal hormone release and renal function, effects partially but not completely explained by APC dependence of SGK1 expression.
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Just A. Going with the Wnt? Focus on "Hyperaldosteronism, hypervolemia, and increased blood pressure in mice expressing defective APC". Am J Physiol Regul Integr Comp Physiol 2009; 297:R568-70. [PMID: 19553497 DOI: 10.1152/ajpregu.00356.2009] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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