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Rumpf M, Pautz S, Drebes B, Herberg FW, Müller HAJ. Microtubule-Associated Serine/Threonine (MAST) Kinases in Development and Disease. Int J Mol Sci 2023; 24:11913. [PMID: 37569286 PMCID: PMC10419289 DOI: 10.3390/ijms241511913] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2023] [Revised: 07/17/2023] [Accepted: 07/19/2023] [Indexed: 08/13/2023] Open
Abstract
Microtubule-Associated Serine/Threonine (MAST) kinases represent an evolutionary conserved branch of the AGC protein kinase superfamily in the kinome. Since the discovery of the founding member, MAST2, in 1993, three additional family members have been identified in mammals and found to be broadly expressed across various tissues, including the brain, heart, lung, liver, intestine and kidney. The study of MAST kinases is highly relevant for unraveling the molecular basis of a wide range of different human diseases, including breast and liver cancer, myeloma, inflammatory bowel disease, cystic fibrosis and various neuronal disorders. Despite several reports on potential substrates and binding partners of MAST kinases, the molecular mechanisms that would explain their involvement in human diseases remain rather obscure. This review will summarize data on the structure, biochemistry and cell and molecular biology of MAST kinases in the context of biomedical research as well as organismal model systems in order to provide a current profile of this field.
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Affiliation(s)
- Marie Rumpf
- Department of Developmental Genetics, Institute of Biology, University of Kassel, 34321 Kassel, Germany; (M.R.)
| | - Sabine Pautz
- Department of Biochemistry, Institute of Biology, University of Kassel, 34321 Kassel, Germany
| | - Benedikt Drebes
- Department of Developmental Genetics, Institute of Biology, University of Kassel, 34321 Kassel, Germany; (M.R.)
| | - Friedrich W. Herberg
- Department of Biochemistry, Institute of Biology, University of Kassel, 34321 Kassel, Germany
| | - Hans-Arno J. Müller
- Department of Developmental Genetics, Institute of Biology, University of Kassel, 34321 Kassel, Germany; (M.R.)
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2
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An SWA, Choi E, Hwang W, Son HG, Yang J, Seo K, Nam H, Nguyen NTH, Kim EJE, Suh BK, Kim Y, Nakano S, Ryu Y, Man Ha C, Mori I, Park SK, Yoo J, Kim S, Lee SV. KIN-4/MAST kinase promotes PTEN-mediated longevity of Caenorhabditis elegans via binding through a PDZ domain. Aging Cell 2019; 18:e12906. [PMID: 30773781 PMCID: PMC6516182 DOI: 10.1111/acel.12906] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2018] [Revised: 11/16/2018] [Accepted: 12/02/2018] [Indexed: 01/09/2023] Open
Abstract
PDZ domain‐containing proteins (PDZ proteins) act as scaffolds for protein–protein interactions and are crucial for a variety of signal transduction processes. However, the role of PDZ proteins in organismal lifespan and aging remains poorly understood. Here, we demonstrate that KIN‐4, a PDZ domain‐containing microtubule‐associated serine‐threonine (MAST) protein kinase, is a key longevity factor acting through binding PTEN phosphatase in Caenorhabditis elegans. Through a targeted genetic screen for PDZ proteins, we find that kin‐4 is required for the long lifespan of daf‐2/insulin/IGF‐1 receptor mutants. We then show that neurons are crucial tissues for the longevity‐promoting role of kin‐4. We find that the PDZ domain of KIN‐4 binds PTEN, a key factor for the longevity of daf‐2 mutants. Moreover, the interaction between KIN‐4 and PTEN is essential for the extended lifespan of daf‐2 mutants. As many aspects of lifespan regulation in C. elegans are evolutionarily conserved, MAST family kinases may regulate aging and/or age‐related diseases in mammals through their interaction with PTEN.
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Affiliation(s)
- Seon Woo A. An
- Department of Life Sciences Pohang University of Science and Technology Pohang Gyeongbuk South Korea
| | - Eun‐Seok Choi
- Department of Life Sciences Pohang University of Science and Technology Pohang Gyeongbuk South Korea
| | - Wooseon Hwang
- Department of Life Sciences Pohang University of Science and Technology Pohang Gyeongbuk South Korea
| | - Heehwa G. Son
- Department of Life Sciences Pohang University of Science and Technology Pohang Gyeongbuk South Korea
| | - Jae‐Seong Yang
- School of Interdisciplinary Bioscience and Bioengineering Pohang University of Science and Technology Pohang Gyeongbuk South Korea
| | - Keunhee Seo
- Department of Life Sciences Pohang University of Science and Technology Pohang Gyeongbuk South Korea
| | - Hyun‐Jun Nam
- School of Interdisciplinary Bioscience and Bioengineering Pohang University of Science and Technology Pohang Gyeongbuk South Korea
| | - Nhung T. H. Nguyen
- Department of Life Sciences Pohang University of Science and Technology Pohang Gyeongbuk South Korea
| | - Eun Ji E. Kim
- Department of Life Sciences Pohang University of Science and Technology Pohang Gyeongbuk South Korea
| | - Bo Kyoung Suh
- Department of Life Sciences Pohang University of Science and Technology Pohang Gyeongbuk South Korea
| | - Youngran Kim
- Department of Life Sciences Pohang University of Science and Technology Pohang Gyeongbuk South Korea
| | - Shunji Nakano
- Neuroscience Institute, Graduate School of Science Nagoya University Nagoya Japan
| | - Youngjae Ryu
- Research Division Korea Brain Research Institute Daegu South Korea
| | - Chang Man Ha
- Research Division Korea Brain Research Institute Daegu South Korea
| | - Ikue Mori
- Neuroscience Institute, Graduate School of Science Nagoya University Nagoya Japan
| | - Sang Ki Park
- Department of Life Sciences Pohang University of Science and Technology Pohang Gyeongbuk South Korea
| | - Joo‐Yeon Yoo
- Department of Life Sciences Pohang University of Science and Technology Pohang Gyeongbuk South Korea
| | - Sanguk Kim
- Department of Life Sciences Pohang University of Science and Technology Pohang Gyeongbuk South Korea
- School of Interdisciplinary Bioscience and Bioengineering Pohang University of Science and Technology Pohang Gyeongbuk South Korea
| | - Seung‐Jae V. Lee
- Department of Life Sciences Pohang University of Science and Technology Pohang Gyeongbuk South Korea
- School of Interdisciplinary Bioscience and Bioengineering Pohang University of Science and Technology Pohang Gyeongbuk South Korea
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3
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Hernando N. NaPi-IIa interacting partners and their (un)known functional roles. Pflugers Arch 2018; 471:67-82. [PMID: 30022249 DOI: 10.1007/s00424-018-2176-2] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2018] [Accepted: 06/26/2018] [Indexed: 01/14/2023]
Abstract
The sorting and stabilization of proteins at specific subcellular domains depend upon the formation of networks build up by specific protein-protein interactions. In addition, protein networks also ensure the specificity of many regulatory processes by bringing together regulatory molecules with their targets. Whereas the success on the identification of protein-protein interactions is (up to a point) technology-driven, the assignment of functional roles to specific partners remains a major challenge. This review summarizes the work that led to the identification of partners of the Na+/phosphate cotransporter NaPi-IIa as well as the effects of the interactions in the expression and/or regulation of the cotransporter.
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Affiliation(s)
- Nati Hernando
- Institute of Physiology, University Zurich, Winterthurerstrasse 190, 8057, Zurich, Switzerland.
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4
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Musante V, Li L, Kanyo J, Lam TT, Colangelo CM, Cheng SK, Brody AH, Greengard P, Le Novère N, Nairn AC. Reciprocal regulation of ARPP-16 by PKA and MAST3 kinases provides a cAMP-regulated switch in protein phosphatase 2A inhibition. eLife 2017; 6. [PMID: 28613156 PMCID: PMC5515580 DOI: 10.7554/elife.24998] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2017] [Accepted: 06/13/2017] [Indexed: 12/17/2022] Open
Abstract
ARPP-16, ARPP-19, and ENSA are inhibitors of protein phosphatase PP2A. ARPP-19 and ENSA phosphorylated by Greatwall kinase inhibit PP2A during mitosis. ARPP-16 is expressed in striatal neurons where basal phosphorylation by MAST3 kinase inhibits PP2A and regulates key components of striatal signaling. The ARPP-16/19 proteins were discovered as substrates for PKA, but the function of PKA phosphorylation is unknown. We find that phosphorylation by PKA or MAST3 mutually suppresses the ability of the other kinase to act on ARPP-16. Phosphorylation by PKA also acts to prevent inhibition of PP2A by ARPP-16 phosphorylated by MAST3. Moreover, PKA phosphorylates MAST3 at multiple sites resulting in its inhibition. Mathematical modeling highlights the role of these three regulatory interactions to create a switch-like response to cAMP. Together, the results suggest a complex antagonistic interplay between the control of ARPP-16 by MAST3 and PKA that creates a mechanism whereby cAMP mediates PP2A disinhibition. DOI:http://dx.doi.org/10.7554/eLife.24998.001
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Affiliation(s)
- Veronica Musante
- Department of Psychiatry, Yale University School of Medicine, New Haven, United States
| | - Lu Li
- The Babraham Institute, Cambridge, United Kingdom
| | - Jean Kanyo
- W.M. Keck Biotechnology Resource Laboratory, Yale University School Medicine, New Haven, United states
| | - Tukiet T Lam
- W.M. Keck Biotechnology Resource Laboratory, Yale University School Medicine, New Haven, United states
| | - Christopher M Colangelo
- W.M. Keck Biotechnology Resource Laboratory, Yale University School Medicine, New Haven, United states
| | - Shuk Kei Cheng
- Laboratory of Molecular and Cellular Neuroscience, The Rockefeller University, New York, United States
| | - A Harrison Brody
- Laboratory of Molecular and Cellular Neuroscience, The Rockefeller University, New York, United States
| | - Paul Greengard
- Laboratory of Molecular and Cellular Neuroscience, The Rockefeller University, New York, United States
| | | | - Angus C Nairn
- Department of Psychiatry, Yale University School of Medicine, New Haven, United States
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5
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Hain D, Langlands A, Sonnenberg HC, Bailey C, Bullock SL, Müller HAJ. The Drosophila MAST kinase Drop out is required to initiate membrane compartmentalisation during cellularisation and regulates dynein-based transport. Development 2014; 141:2119-30. [PMID: 24803657 PMCID: PMC4011086 DOI: 10.1242/dev.104711] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
Cellularisation of the Drosophila syncytial blastoderm embryo into the polarised blastoderm epithelium provides an excellent model with which to determine how cortical plasma membrane asymmetry is generated during development. Many components of the molecular machinery driving cellularisation have been identified, but cell signalling events acting at the onset of membrane asymmetry are poorly understood. Here we show that mutations in drop out (dop) disturb the segregation of membrane cortical compartments and the clustering of E-cadherin into basal adherens junctions in early cellularisation. dop is required for normal furrow formation and controls the tight localisation of furrow canal proteins and the formation of F-actin foci at the incipient furrows. We show that dop encodes the single Drosophila homologue of microtubule-associated Ser/Thr (MAST) kinases. dop interacts genetically with components of the dynein/dynactin complex and promotes dynein-dependent transport in the embryo. Loss of dop function reduces phosphorylation of Dynein intermediate chain, suggesting that dop is involved in regulating cytoplasmic dynein activity through direct or indirect mechanisms. These data suggest that Dop impinges upon the initiation of furrow formation through developmental regulation of cytoplasmic dynein.
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Affiliation(s)
- Daniel Hain
- Division of Cell and Developmental Biology, College of Life Sciences, University of Dundee, Dundee DD1 5EH, UK
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6
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Ren A, Zhang W, Yarlagadda S, Sinha C, Arora K, Moon CS, Naren AP. MAST205 competes with cystic fibrosis transmembrane conductance regulator (CFTR)-associated ligand for binding to CFTR to regulate CFTR-mediated fluid transport. J Biol Chem 2013; 288:12325-34. [PMID: 23504457 DOI: 10.1074/jbc.m112.432724] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
The PDZ (postsynaptic density-95/discs large/zona occludens-1) domain-based interactions play important roles in regulating the expression and function of the cystic fibrosis transmembrane conductance regulator (CFTR). Several PDZ domain-containing proteins (PDZ proteins for short) have been identified as directly or indirectly interacting with the C terminus of CFTR. To better understand the regulation of CFTR processing, we conducted a genetic screen and identified MAST205 (a microtubule-associated serine/threonine kinase with a molecular mass of 205 kDa) as a new CFTR regulator. We found that overexpression of MAST205 increased the expression of CFTR and augmented CFTR-mediated fluid transport in a dose-dependent manner. Conversely, knockdown of MAST205 inhibited CFTR function. The PDZ motif of CFTR is required for the regulatory role of MAST205 in CFTR expression and function. We further demonstrated that MAST205 and the CFTR-associated ligand competed for binding to CFTR, which facilitated the processing of CFTR and consequently up-regulated the expression and function of CFTR at the plasma membrane. More importantly, we found that MAST205 could facilitate the processing of F508del-CFTR mutant and augment its quantity and channel function at the plasma membrane. Taken together, our data suggest that MAST205 plays an important role in regulating CFTR expression and function. Our findings have important clinical implications for treating CFTR-associated diseases such as cystic fibrosis and secretory diarrheas.
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Affiliation(s)
- Aixia Ren
- Department of Physiology, University of Tennessee Health Science Center, Memphis, Tennessee 38163, USA
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7
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Abstract
PDZ (PSD-95/Disc large/Zonula occludens-1) protein interaction domains bind to cytoplasmic protein C-termini of transmembrane proteins. In order to identify new interaction partners of the voltage-gated L-type Ca2+ channel 1.2 and the plasma membrane Ca2+ ATPase 4b (PMCA4b), we used PDZ domain arrays probing for 124 PDZ domains. We confirmed this by GST pull-downs and immunoprecipitations. In PDZ arrays, strongest interactions with 1.2 and PMCA4b were found for the PDZ domains of SAP-102, MAST-205, MAGI-1, MAGI-2, MAGI-3, and ZO-1. We observed binding of the 1.2 C-terminus to PDZ domains of NHERF1/2, Mint-2, and CASK. PMCA4b was observed to interact with Mint-2 and its known interactions with Chapsyn-110 and CASK were confirmed. Furthermore, we validated interaction of 1.2 and PMCA4b with NHERF1/2, CASK, MAST-205 and MAGI-3 via immunoprecipitation. We also verified the interaction of 1.2 and nNOS and hypothesized that nNOS overexpression might reduce Ca2+ influx through 1.2. To address this, we measured Ca2+ currents in HEK 293 cells co-expressing 1.2 and nNOS and observed reduced voltage-dependent 1.2 activation. Taken together, we conclude that 1.2 and PMCA4b bind promiscuously to various PDZ domains, and that our data provides the basis for further investigation of the physiological consequences of these interactions.
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8
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Bryantseva SA, Gavryushina ES, Yemets AI, Karpov PA, Blume YB, Drygin YF, Nadezhdina ES. MAST2-like proteinkinase from grape Vitis vinifera: Cloning of catalytic domain cDNA. CYTOL GENET+ 2010. [DOI: 10.3103/s0095452710040079] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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9
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He P, Klein J, Yun CC. Activation of Na+/H+ exchanger NHE3 by angiotensin II is mediated by inositol 1,4,5-triphosphate (IP3) receptor-binding protein released with IP3 (IRBIT) and Ca2+/calmodulin-dependent protein kinase II. J Biol Chem 2010; 285:27869-78. [PMID: 20584908 DOI: 10.1074/jbc.m110.133066] [Citation(s) in RCA: 60] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
Angiotensin II (ANG II) stimulates renal tubular reabsorption of NaCl by targeting Na(+)/H(+) exchanger NHE3. We have shown previously that inositol 1,4,5-triphosphate receptor-binding protein released with inositol 1,4,5-triphosphate (IRBIT) plays a critical role in stimulation of NHE3 in response to elevated intracellular Ca(2+) concentration ([Ca(2+)](i)). In this study, we investigated the role of IRBIT in mediating NHE3 activation by ANG II. IRBIT is abundantly expressed in the proximal tubules where NHE3 is located. ANG II at physiological concentrations stimulates NHE3 transport activity in a model proximal tubule cell line. ANG II-induced activation of NHE3 was abrogated by knockdown of IRBIT, whereas overexpression of IRBIT enhanced the effect of ANG II on NHE3. ANG II transiently increased binding of IRBIT to NHE3 at 5 min but became dissociated by 45 min. In comparison, it took at least 15 min of ANG II treatment for an increase in NHE3 activity and NHE3 surface expression. The stimulation of NHE3 by ANG II was dependent on changes in [Ca(2+)](i) and Ca(2+)/calmodulin-dependent protein kinases II. Inhibition of CaMKII completely blocked the ANG II-induced binding of IRBIT to NHE3 and the increase in NHE3 surface abundance. Several serine residues of IRBIT are thought to be important for IRBIT binding. Mutations of Ser-68, Ser-71, and Ser-74 of IRBIT decreased binding of IRBIT to NHE3 and its effect on NHE3 activity. In conclusion, our current findings demonstrate that IRBIT is critically involved in mediating activation of NHE3 by ANG II via a Ca(2+)/calmodulin-dependent protein kinases II-dependent pathway.
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Affiliation(s)
- Peijian He
- Division of Digestive Diseases, Department of Medicine, Emory University, Atlanta, Georgia 30324, USA
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10
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Park HJ, Rajbhandari I, Yang HS, Lee S, Cucoranu D, Cooper DS, Klein JD, Sands JM, Choi I. Neuronal expression of sodium/bicarbonate cotransporter NBCn1 (SLC4A7) and its response to chronic metabolic acidosis. Am J Physiol Cell Physiol 2010; 298:C1018-28. [PMID: 20147654 DOI: 10.1152/ajpcell.00492.2009] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
The sodium-bicarbonate cotransporter NBCn1 (SLC4A7) is an acid-base transporter that normally moves Na(+) and HCO(3)(-) into the cell. This membrane protein is sensitive to cellular and systemic pH changes. We examined NBCn1 expression and localization in the brain and its response to chronic metabolic acidosis. Two new NBCn1 antibodies were generated by immunizing a rabbit and a guinea pig. The antibodies stained neurons in a variety of rat brain regions, including hippocampal pyramidal neurons, dentate gyrus granular neurons, posterior cortical neurons, and cerebellar Purkinje neurons. Choroid plexus epithelia were also stained. Double immunofluorescence labeling showed that NBCn1 and the postsynaptic density protein PSD-95 were found in the same hippocampal CA3 neurons and partially colocalized in dendrites. PSD-95 was pulled down from rat brain lysates with the GST/NBCn1 fusion protein and was also coimmunoprecipitated with NBCn1. Chronic metabolic acidosis was induced by feeding rats with normal chow or 0.4 M HCl-containing chow for 7 days. Real-time PCR and immunoblot showed upregulation of NBCn1 mRNA and protein in the hippocampus of acidotic rats. NBCn1 immunostaining was enhanced in CA3 neurons, posterior cortical neurons, and cerebellar granular cells. Intraperitoneal administration of N-methyl-d-aspartate caused neuronal death determined by caspase-3 activity, and this effect was more severe in acidotic rats. Administering N-methyl-d-aspartate also inhibited NBCn1 upregulation in acidotic rats. We conclude that NBCn1 in neurons is upregulated by chronic acid loads, and this upregulation is associated with glutamate excitotoxicity.
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Affiliation(s)
- Hae Jeong Park
- Dept. of Physiology, Emory Univ., Atlanta, GA 30322, USA
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11
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Cooper DS, Yang HS, He P, Kim E, Rajbhandari I, Yun CC, Choi I. Sodium/bicarbonate cotransporter NBCn1/slc4a7 increases cytotoxicity in magnesium depletion in primary cultures of hippocampal neurons. Eur J Neurosci 2008; 29:437-46. [PMID: 19170751 DOI: 10.1111/j.1460-9568.2008.06611.x] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Growing evidence suggests that pharmacological inhibition of Na/H exchange and Na/HCO(3) transport provides protection against damage or injury in cardiac ischemia. In this study, we examined the contribution of the sodium/bicarbonate cotransporter NBCn1 (slc4a7) to cytotoxicity in cultured hippocampal neurons of rats. In neurons exposed to extracellular pH (pH(o)) ranging from 6.2 to 8.3, NBCn1 protein expression increased by fivefold at pH < 6.5 compared to the expression at pH(o) 7.4. At pH(o) 6.5, the intracellular pH of neurons was approximately 1 unit lower than that at pH 7.4. Immunochemistry showed a marked increase in NBCn1 immunofluorescence in plasma membranes and cytosol of the soma as well as in dendrites, at pH(o) 6.5. NBCn1 expression also increased by 40% in a prolonged Mg(2+)-free incubation at normal pH(o). Knockdown of NBCn1 in neurons had negligible effect on cell viability. The effect of NBCn1 knockdown on cytotoxicity was then determined by exposing neurons to 0.5 mm glutamate for 10 min and measuring lactate dehydrogenase (LDH) release from neurons. Compared to normal incubation (pH(o) 7.2 for 6 h) after glutamate exposure, acidic incubation (pH(o) 6.3 for 6 h) reduced cytotoxicity by 75% for control neurons and 78% for NBCn1-knockdown neurons. Thus, both controls and knockdown neurons showed acidic protection from cytotoxicity. However, in Mg(2+)-free incubation after glutamate exposure, NBCn1 knockdown progressively attenuated cytotoxicity. This attenuation was unaffected by acidic preincubation before glutamate exposure. We conclude that NBCn1 has a dynamic upregulation in low pH(o) and Mg(2+) depletion. NBCn1 is not required for acidic protection, but increases cytotoxicity in Mg(2+)-free conditions.
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Affiliation(s)
- Deborah S Cooper
- Department of Physiology, Emory University School of Medicine, Atlanta, GA 30322, USA
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12
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Garland P, Quraishe S, French P, O'Connor V. Expression of the MAST family of serine/threonine kinases. Brain Res 2007; 1195:12-9. [PMID: 18206861 DOI: 10.1016/j.brainres.2007.12.027] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2007] [Revised: 10/27/2007] [Accepted: 12/16/2007] [Indexed: 11/18/2022]
Abstract
The Microtubule-Associated Serine/Threonine Kinase family (MAST1-4, and MAST-like) is characterised by the presence of a serine/threonine kinase domain and a postsynaptic density protein-95/discs large/zona occludens-1 domain (PDZ). This latter domain gives the MAST family the capacity to scaffold its own kinase activity. In the present study we have profiled the mRNA for each member of the MAST family transcripts across various tissues, with particular focus on rodent brain. Reverse-transcriptase polymerase chain reaction (RT-PCR) has shown equivalent patterns of expression for MAST1 and 2 in multiple tissues. Both MAST3 and 4 show more distinct expression in several tissues, and MAST-like appears to be predominantly expressed in heart and testis. In situ hybridisation reveals overlapping expression of MAST1 and 2 in specific brain regions. In contrast, MAST3 shows selective expression in the striatum and cerebral cortex. MAST4 also exhibits distinct expression in oligodendrocytes of white matter containing brain regions. In keeping with previous results, this family member also shows increased expression in the hippocampus following seizure-like activity. Our analysis of MAST family expression provides support for the role of these kinases in a broad range of neural functions.
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Affiliation(s)
- Patrick Garland
- University of Southampton, School of Biological Sciences, Boldrewood, Basssett Crescent East, Southampton, SO16 7PX, UK
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13
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Orlowski J, Grinstein S. Emerging roles of alkali cation/proton exchangers in organellar homeostasis. Curr Opin Cell Biol 2007; 19:483-92. [PMID: 17646094 PMCID: PMC5021530 DOI: 10.1016/j.ceb.2007.06.001] [Citation(s) in RCA: 89] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2007] [Revised: 05/31/2007] [Accepted: 06/08/2007] [Indexed: 11/28/2022]
Abstract
The regulated movement of monovalent cations such as H(+), Li(+), Na(+) and K(+) across biological membranes influences a myriad of cellular processes and is fundamental to all living organisms. This is accomplished by a multiplicity of ion channels, pumps and transporters. Our insight into their molecular, cellular and physiological diversity has increased greatly in the past few years with the advent of genome sequencing, genetic manipulation and sophisticated imaging techniques. One of the revelations from these studies is the emergence of novel alkali cation/protons exchangers that are present in endomembranes, where they function to regulate not only intraorganellar pH but also vesicular biogenesis, trafficking and other aspects of cellular homeostasis.
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Affiliation(s)
- John Orlowski
- Department of Physiology, McGill University, McIntyre Medical Science Bldg. 3655 Promenade Sir-William-Osler, Montreal, Quebec H3G 1Y6, Canada
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14
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Wang D, Zhang H, Lang F, Yun CC. Acute activation of NHE3 by dexamethasone correlates with activation of SGK1 and requires a functional glucocorticoid receptor. Am J Physiol Cell Physiol 2006; 292:C396-404. [PMID: 16971495 PMCID: PMC2695591 DOI: 10.1152/ajpcell.00345.2006] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Glucocorticoids stimulate the intestinal absorption of Na(+) and water partly by regulation of the Na(+)/H(+) exchanger 3 (NHE3). Previous studies have shown both genomic and nongenomic regulation of NHE3 by glucocorticoids. Serum and glucocorticoid-inducible kinase 1 (SGK1) has been shown to be part of this cascade, where phosphorylation of NHE3 by SGK1 initiates the translocation of NHE3 to the cell surface. In the present work, we examined a series of changes in SGK1 and NHE3 induced by glucocorticoids using human colonic Caco-2 and opossum kidney cells. We found that dexamethasone rapidly stimulated SGK1 mRNAs, but a significant change in protein abundance was not detected. Instead, there was an increase in SGK1 kinase activity as early as at 2 h. An increase in NHE3 protein abundance was not detected until 12 h of dexamethasone exposure, although the transport activity was significantly stimulated at 4 h. These data demonstrate that the changes of SGK1 precede those of NHE3. Chronic regulation (24 h) of NHE3 was blocked completely by prevention of protein synthesis with cycloheximide or actinomycin D and by the glucocorticoid receptor blocker RU486. The acute effect of dexamethasone was similarly abrogated by RU486, but was insensitive to cycloheximide and actinomycin D. Similarly, the stimulation of SGK1 activity by dexamethasone was blocked by RU486 but not by actinomycin D. Together, these data show that the acute effect of glucocorticoids on NHE3 is mediated by a glucocorticoid receptor dependent mechanism that activates SGK1 in a nongenomic manner.
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Affiliation(s)
- Dongsheng Wang
- Department of Physiology, Emory University School of Medicine, 615 Michael Street, Atlanta, GA 30322, USA
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