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Fan Q, Yin X, Rababa'h A, Diaz Diaz A, Wijaya CS, Singh S, Suryavanshi SV, Vo HH, Saeed M, Zhang Y, McConnell BK. Absence of gravin-mediated signaling inhibits development of high-fat diet-induced hyperlipidemia and atherosclerosis. Am J Physiol Heart Circ Physiol 2019; 317:H793-H810. [PMID: 31441691 DOI: 10.1152/ajpheart.00215.2019] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Gravin, an A-kinase anchoring protein, is known to play a role in regulating key processes that lead to inflammation and atherosclerosis development, namely, cell migration, proliferation, and apoptosis. We investigated the role of gravin in the development of high-fat diet (HFD)-induced atherosclerosis and hyperlipidemia. Five-week-old male wild-type (WT) and gravin-t/t mice were fed a normal diet or an HFD for 16 wk. Gravin-t/t mice showed significantly lower liver-to-body-weight ratio, cholesterol, triglyceride, and very low-density lipoprotein levels in serum as compared with WT mice on HFD. Furthermore, there was less aortic plaque formation coupled with decreased lipid accumulation and liver damage, as the gravin-t/t mice had lower levels of serum alanine aminotransferase and aspartate aminotransferase. Additionally, gravin-t/t HFD-fed mice had decreased expression of liver 3-hydroxy-3-methyl-glutaryl-CoA reductase, an essential enzyme for cholesterol synthesis and lower fatty acid synthase expression. Gravin-t/t HFD-fed mice also exhibited inhibition of sterol regulatory element binding protein-2 (SREBP-2) expression, a liver transcription factor associated with the regulation of lipid transportation. In response to platelet-derived growth factor receptor treatment, gravin-t/t vascular smooth muscle cells exhibited lower intracellular calcium transients and decreased protein kinase A- and protein kinase C-dependent substrate phosphorylation, notably involving the Erk1/2 signaling pathway. Collectively, these results suggest the involvement of gravin-dependent regulation of lipid metabolism via the reduction of SREBP-2 expression. The absence of gravin-mediated signaling lowers blood pressure, reduces plaque formation in the aorta, and decreases lipid accumulation and damage in the liver of HFD mice. Through these processes, the absence of gravin-mediated signaling complex delays the HFD-induced hyperlipidemia and atherosclerosis.NEW & NOTEWORTHY The gravin scaffolding protein plays a key role in the multiple enzymatic pathways of lipid metabolism. We have shown for the first time the novel role of gravin in regulating the pathways related to the initiation and progression of atherosclerosis. Specifically, an absence of gravin-mediated signaling decreases the lipid levels (cholesterol, triglyceride, and VLDL) that are associated with sterol regulatory element binding protein-2 downregulation.
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Affiliation(s)
- Qiying Fan
- Department of Pharmacological and Pharmaceutical Sciences, College of Pharmacy, University of Houston, Houston, Texas
| | - Xing Yin
- Department of Pharmacological and Pharmaceutical Sciences, College of Pharmacy, University of Houston, Houston, Texas
| | - Abeer Rababa'h
- Department of Clinical Pharmacy, Faculty of Pharmacy, Jordan University of Science and Technology, Irbid, Jordan
| | - Andrea Diaz Diaz
- Department of Pharmacological and Pharmaceutical Sciences, College of Pharmacy, University of Houston, Houston, Texas
| | - Cori S Wijaya
- Department of Pharmacological and Pharmaceutical Sciences, College of Pharmacy, University of Houston, Houston, Texas
| | - Sonal Singh
- Department of Pharmacological and Pharmaceutical Sciences, College of Pharmacy, University of Houston, Houston, Texas
| | - Santosh V Suryavanshi
- Department of Pharmacological and Pharmaceutical Sciences, College of Pharmacy, University of Houston, Houston, Texas
| | - Henry Hiep Vo
- Department of Pharmacological and Pharmaceutical Sciences, College of Pharmacy, University of Houston, Houston, Texas
| | - Moawiz Saeed
- Department of Pharmacological and Pharmaceutical Sciences, College of Pharmacy, University of Houston, Houston, Texas
| | - Yang Zhang
- Department of Pharmacological and Pharmaceutical Sciences, College of Pharmacy, University of Houston, Houston, Texas
| | - Bradley K McConnell
- Department of Pharmacological and Pharmaceutical Sciences, College of Pharmacy, University of Houston, Houston, Texas
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Jarrett SG, Wolf Horrell EM, D'Orazio JA. AKAP12 mediates PKA-induced phosphorylation of ATR to enhance nucleotide excision repair. Nucleic Acids Res 2016; 44:10711-10726. [PMID: 27683220 PMCID: PMC5159552 DOI: 10.1093/nar/gkw871] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2016] [Revised: 09/16/2016] [Accepted: 09/21/2016] [Indexed: 12/30/2022] Open
Abstract
Loss-of-function in melanocortin 1 receptor (MC1R), a GS protein-coupled receptor that regulates signal transduction through cAMP and protein kinase A (PKA) in melanocytes, is a major inherited melanoma risk factor. Herein, we report a novel cAMP-mediated response for sensing and responding to UV-induced DNA damage regulated by A-kinase-anchoring protein 12 (AKAP12). AKAP12 is identified as a necessary participant in PKA-mediated phosphorylation of ataxia telangiectasia mutated and Rad3-related (ATR) at S435, a post-translational event required for cAMP-enhanced nucleotide excision repair (NER). Moreover, UV exposure promotes ATR-directed phosphorylation of AKAP12 at S732, which promotes nuclear translocation of AKAP12–ATR-pS435. This complex subsequently recruits XPA to UV DNA damage and enhances 5′ strand incision. Preventing AKAP12's interaction with PKA or with ATR abrogates ATR-pS435 accumulation, delays recruitment of XPA to UV-damaged DNA, impairs NER and increases UV-induced mutagenesis. Our results define a critical role for AKAP12 as an UV-inducible scaffold for PKA-mediated ATR phosphorylation, and identify a repair complex consisting of AKAP12–ATR-pS435-XPA at photodamage, which is essential for cAMP-enhanced NER.
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Affiliation(s)
- Stuart G Jarrett
- Markey Cancer Center, University of Kentucky College of Medicine, Lexington, KY 40536, USA
| | - Erin M Wolf Horrell
- Markey Cancer Center, University of Kentucky College of Medicine, Lexington, KY 40536, USA.,Department of Physiology, University of Kentucky College of Medicine, Lexington, KY 40536, USA
| | - John A D'Orazio
- Markey Cancer Center, University of Kentucky College of Medicine, Lexington, KY 40536, USA .,Department of Physiology, University of Kentucky College of Medicine, Lexington, KY 40536, USA.,Department of Toxicology and Cancer Biology, University of Kentucky College of Medicine, Lexington, KY 40536, USA.,Department of Pharmacology and Nutritional Science, University of Kentucky College of Medicine, Lexington, KY 40536, USA.,Department of Pediatrics, University of Kentucky College of Medicine, Lexington, KY 40536, USA
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3
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Poppinga WJ, Muñoz-Llancao P, González-Billault C, Schmidt M. A-kinase anchoring proteins: cAMP compartmentalization in neurodegenerative and obstructive pulmonary diseases. Br J Pharmacol 2014; 171:5603-23. [PMID: 25132049 PMCID: PMC4290705 DOI: 10.1111/bph.12882] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2014] [Revised: 07/14/2014] [Accepted: 08/10/2014] [Indexed: 12/25/2022] Open
Abstract
The universal second messenger cAMP is generated upon stimulation of Gs protein-coupled receptors, such as the β2 -adreneoceptor, and leads to the activation of PKA, the major cAMP effector protein. PKA oscillates between an on and off state and thereby regulates a plethora of distinct biological responses. The broad activation pattern of PKA and its contribution to several distinct cellular functions lead to the introduction of the concept of compartmentalization of cAMP. A-kinase anchoring proteins (AKAPs) are of central importance due to their unique ability to directly and/or indirectly interact with proteins that either determine the cellular content of cAMP, such as β2 -adrenoceptors, ACs and PDEs, or are regulated by cAMP such as the exchange protein directly activated by cAMP. We report on lessons learned from neurons indicating that maintenance of cAMP compartmentalization by AKAP5 is linked to neurotransmission, learning and memory. Disturbance of cAMP compartments seem to be linked to neurodegenerative disease including Alzheimer's disease. We translate this knowledge to compartmentalized cAMP signalling in the lung. Next to AKAP5, we focus here on AKAP12 and Ezrin (AKAP78). These topics will be highlighted in the context of the development of novel pharmacological interventions to tackle AKAP-dependent compartmentalization.
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Affiliation(s)
- W J Poppinga
- Department of Molecular Pharmacology, University of GroningenGroningen, The Netherlands
- Groningen Research Institute for Asthma and COPD (GRIAC), University Medical Center Groningen, University of GroningenGroningen, The Netherlands
| | - P Muñoz-Llancao
- Department of Molecular Pharmacology, University of GroningenGroningen, The Netherlands
- Laboratory of Cell and Neuronal Dynamics (Cenedyn), Department of Biology, Faculty of Sciences, Universidad de ChileSantiago, Chile
- Department of Neuroscience, Section Medical Physiology, University Medical Center Groningen, University of GroningenGroningen, The Netherlands
| | - C González-Billault
- Laboratory of Cell and Neuronal Dynamics (Cenedyn), Department of Biology, Faculty of Sciences, Universidad de ChileSantiago, Chile
| | - M Schmidt
- Department of Molecular Pharmacology, University of GroningenGroningen, The Netherlands
- Groningen Research Institute for Asthma and COPD (GRIAC), University Medical Center Groningen, University of GroningenGroningen, The Netherlands
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4
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Valsecchi F, Konrad C, Manfredi G. Role of soluble adenylyl cyclase in mitochondria. Biochim Biophys Acta Mol Basis Dis 2014; 1842:2555-60. [PMID: 24907564 DOI: 10.1016/j.bbadis.2014.05.035] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2014] [Revised: 05/19/2014] [Accepted: 05/28/2014] [Indexed: 11/25/2022]
Abstract
The soluble adenylyl cyclase (sAC) catalyzes the conversion of ATP into cyclic AMP (cAMP). Recent studies have shed new light on the role of sAC localized in mitochondria and its product cAMP, which drives mitochondrial protein phosphorylation and regulation of the oxidative phosphorylation system and other metabolic enzymes, presumably through the activation of intra-mitochondrial PKA. In this review article, we summarize recent findings on mitochondrial sAC activation by bicarbonate (HCO(3)(-)) and calcium (Ca²⁺) and the effects on mitochondrial metabolism. We also discuss putative mechanisms whereby sAC-mediated mitochondrial protein phosphorylation regulates mitochondrial metabolism. This article is part of a Special Issue entitled: The role of soluble adenylyl cyclase in health and disease.
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Affiliation(s)
- Federica Valsecchi
- Brain and Mind Research Institute, Weill Medical College of Cornell University, New York, NY 10065, USA
| | - Csaba Konrad
- Brain and Mind Research Institute, Weill Medical College of Cornell University, New York, NY 10065, USA
| | - Giovanni Manfredi
- Brain and Mind Research Institute, Weill Medical College of Cornell University, New York, NY 10065, USA.
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Pagnotta SM, Laudanna C, Pancione M, Sabatino L, Votino C, Remo A, Cerulo L, Zoppoli P, Manfrin E, Colantuoni V, Ceccarelli M. Ensemble of gene signatures identifies novel biomarkers in colorectal cancer activated through PPARγ and TNFα signaling. PLoS One 2013; 8:e72638. [PMID: 24133572 PMCID: PMC3795784 DOI: 10.1371/journal.pone.0072638] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2013] [Accepted: 07/11/2013] [Indexed: 12/13/2022] Open
Abstract
We describe a novel bioinformatic and translational pathology approach, gene Signature Finder Algorithm (gSFA) to identify biomarkers associated with Colorectal Cancer (CRC) survival. Here a robust set of CRC markers is selected by an ensemble method. By using a dataset of 232 gene expression profiles, gSFA discovers 16 highly significant small gene signatures. Analysis of dichotomies generated by the signatures results in a set of 133 samples stably classified in good prognosis group and 56 samples in poor prognosis group, whereas 43 remain unreliably classified. AKAP12, DCBLD2, NT5E and SPON1 are particularly represented in the signatures and selected for validation in vivo on two independent patients cohorts comprising 140 tumor tissues and 60 matched normal tissues. Their expression and regulatory programs are investigated in vitro. We show that the coupled expression of NT5E and DCBLD2 robustly stratifies our patients in two groups (one of which with 100% survival at five years). We show that NT5E is a target of the TNF-α signaling in vitro; the tumor suppressor PPARγ acts as a novel NT5E antagonist that positively and concomitantly regulates DCBLD2 in a cancer cell context-dependent manner.
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Affiliation(s)
| | - Carmelo Laudanna
- Department of Sciences and Technologies, University of Sannio, Benevento, Italy
| | - Massimo Pancione
- Department of Sciences and Technologies, University of Sannio, Benevento, Italy
| | - Lina Sabatino
- Department of Sciences and Technologies, University of Sannio, Benevento, Italy
| | - Carolina Votino
- Department of Sciences and Technologies, University of Sannio, Benevento, Italy
| | - Andrea Remo
- Department of Pathology, Hospital "Mater Salutis”, Legnano, Italy
| | - Luigi Cerulo
- Department of Sciences and Technologies, University of Sannio, Benevento, Italy
- Bioinformatics Laboratory, BIOGEM scrl, Ariano Irpino, Italy
| | - Pietro Zoppoli
- Institute for Cancer Genetics, Columbia University, New York, United States of America
| | - Erminia Manfrin
- Department of Surgery and Oncology, University of Verona, Italy
| | - Vittorio Colantuoni
- Department of Sciences and Technologies, University of Sannio, Benevento, Italy
- * E-mail: (MC); (VC)
| | - Michele Ceccarelli
- Department of Sciences and Technologies, University of Sannio, Benevento, Italy
- Bioinformatics Laboratory, BIOGEM scrl, Ariano Irpino, Italy
- * E-mail: (MC); (VC)
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6
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The A-kinase-anchoring protein AKAP-Lbc facilitates cardioprotective PKA phosphorylation of Hsp20 on Ser(16). Biochem J 2012; 446:437-43. [PMID: 22731613 DOI: 10.1042/bj20120570] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
Hsp20 (heat-shock protein of 20 kDa; HspB6) is a cardioprotective agent which combats a number of pathophysiological processes in the heart, including hypertrophy, apoptosis and ischaemia/reperfusion injury. The cardioprotective actions of Hsp20 require its phosphorylation by PKA (cAMP-dependent protein kinase) on Ser(16). Although the extracellular stimuli that promote cAMP-responsive phosphorylation of Hsp20 are well known, less is understood about the molecular processes that regulate this modification. AKAPs (A-kinase-anchoring proteins) physically compartmentalize PKA to specific locations within a cell to both direct PKA phosphorylation toward selected substrates and to orchestrate downstream signalling events. In the present study we used PKA anchoring disruptor peptides to verify that an AKAP underpins the cardioprotective phosphorylation of Hsp20. Biochemical and immunofluorescence techniques identify the cytosolic protein AKAP-Lbc (AKAP13) as the anchoring protein responsible for directing PKA phosphorylation of Hsp20 on Ser(16). Gene silencing and rescue experiments establish that AKAP-Lbc-mediated PKA phosphorylation of Hsp20 is crucial to the anti-apoptotic effects of the Hsp. Thus AKAP-Lbc may serve an ancillary cardioprotective role by favouring the association of PKA with Hsp20.
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Abstract
Spatial and temporal organization of signal transduction is coordinated through the segregation of signaling enzymes in selected cellular compartments. This highly evolved regulatory mechanism ensures the activation of selected enzymes only in the vicinity of their target proteins. In this context, cAMP-responsive triggering of protein kinase A is modulated by a family of scaffold proteins referred to as A-kinase anchoring proteins. A-kinase anchoring proteins form the core of multiprotein complexes and enable simultaneous but segregated cAMP signaling events to occur in defined cellular compartments. In this review we will focus on the description of A-kinase anchoring protein function in the regulation of cardiac physiopathology.
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Affiliation(s)
- Alessia Perino
- Molecular Biotechnology Center, Department of Genetics, Biology and Biochemistry, University of Torino, Torino, Italy
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8
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Pivotal Role of AKAP12 in the Regulation of Cellular Adhesion Dynamics: Control of Cytoskeletal Architecture, Cell Migration, and Mitogenic Signaling. JOURNAL OF SIGNAL TRANSDUCTION 2012; 2012:529179. [PMID: 22811901 PMCID: PMC3395252 DOI: 10.1155/2012/529179] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/24/2012] [Accepted: 05/24/2012] [Indexed: 11/18/2022]
Abstract
Cellular dynamics are controlled by key signaling molecules such as cAMP-dependent protein kinase (PKA) and protein kinase C (PKC). AKAP12/SSeCKS/Gravin (AKAP12) is a scaffold protein for PKA and PKC which controls actin-cytoskeleton reorganization in a spatiotemporal manner. AKAP12 also acts as a tumor suppressor which regulates cell-cycle progression and inhibits Src-mediated oncogenic signaling and cytoskeletal pathways. Reexpression of AKAP12 causes cell flattening, reorganization of the actin cytoskeleton, and the production of normalized focal adhesion structures. Downregulation of AKAP12 induces the formation of thickened, longitudinal stress fibers and the proliferation of adhesion complexes. AKAP12-null mouse embryonic fibroblasts exhibit hyperactivation of PKC, premature cellular senescence, and defects in cytokinesis, relating to the loss of PKC scaffolding activity by AKAP12. AKAP12-null mice exhibit increased cell senescence and increased susceptibility to carcinogen-induced oncogenesis. The paper describes the regulatory and scaffolding functions of AKAP12 and how it regulates cell adhesion, signaling, and oncogenic suppression.
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Kool J, Jonker N, Irth H, Niessen WMA. Studying protein-protein affinity and immobilized ligand-protein affinity interactions using MS-based methods. Anal Bioanal Chem 2011; 401:1109-25. [PMID: 21755271 PMCID: PMC3151372 DOI: 10.1007/s00216-011-5207-9] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2011] [Revised: 06/12/2011] [Accepted: 06/24/2011] [Indexed: 12/31/2022]
Abstract
This review discusses the most important current methods employing mass spectrometry (MS) analysis for the study of protein affinity interactions. The methods are discussed in depth with particular reference to MS-based approaches for analyzing protein-protein and protein-immobilized ligand interactions, analyzed either directly or indirectly. First, we introduce MS methods for the study of intact protein complexes in the gas phase. Next, pull-down methods for affinity-based analysis of protein-protein and protein-immobilized ligand interactions are discussed. Presently, this field of research is often called interactomics or interaction proteomics. A slightly different approach that will be discussed, chemical proteomics, allows one to analyze selectivity profiles of ligands for multiple drug targets and off-targets. Additionally, of particular interest is the use of surface plasmon resonance technologies coupled with MS for the study of protein interactions. The review addresses the principle of each of the methods with a focus on recent developments and the applicability to lead compound generation in drug discovery as well as the elucidation of protein interactions involved in cellular processes. The review focuses on the analysis of bioaffinity interactions of proteins with other proteins and with ligands, where the proteins are considered as the bioactives analyzed by MS.
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Affiliation(s)
- Jeroen Kool
- BioMolecular Analysis, Department of Chemistry and Pharmaceutical Sciences, Faculty of Sciences, VU University Amsterdam, Amsterdam, The Netherlands.
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10
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Liu W, Guan M, Hu T, Gu X, Lu Y. Re-expression of AKAP12 inhibits progression and metastasis potential of colorectal carcinoma in vivo and in vitro. PLoS One 2011; 6:e24015. [PMID: 21918680 PMCID: PMC3168868 DOI: 10.1371/journal.pone.0024015] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2011] [Accepted: 08/02/2011] [Indexed: 01/01/2023] Open
Abstract
Background AKAP12/Gravin (A kinase anchor protein 12) is one of the A-kinase scaffold proteins and a potential tumor suppressor gene in human primary cancers. Our recent study demonstrated the highly recurrent loss of AKAP12 in colorectal cancer and AKAP12 reexpression inhibited proliferation and anchorage-independent growth in colorectal cancer cells, implicating AKAP12 in colorectal cancer pathogenesis. Methods To evaluate the effect of this gene on the progression and metastasis of colorectal cancer, we examined the impact of overexpressing AKAP12 in the AKAP12-negative human colorectal cancer cell line LoVo, the single clone (LoVo-AKAP12) compared to mock-transfected cells (LoVo-CON). Results pCMV6-AKAP12-mediated AKAP12 re-expression induced apoptosis (3% to 12.7%, p<0.01), migration (89.6±7.5 cells to 31.0±4.1 cells, p<0.01) and invasion (82.7±5.2 cells to 24.7±3.3 cells, p<0.01) of LoVo cells in vitro compared to control cells. Nude mice injected with LoVo-AKAP12 cells had both significantly reduced tumor volume (p<0.01) and increased apoptosis compared to mice given AKAP12-CON. The quantitative human-specific Alu PCR analysis showed overexpression of AKAP12 suppressed the number of intravasated cells in vivo (p<0.01). Conclusion These results demonstrate that AKAP12 may play an important role in tumor growth suppression and the survival of human colorectal cancer.
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Affiliation(s)
- Weiwei Liu
- Department of Laboratory Medicine, Huashan Hospital, Shanghai Medical College, Fudan University, Shanghai, People's Republic of China
- * E-mail: (YL); (WL)
| | - Ming Guan
- Department of Laboratory Medicine, Huashan Hospital, Shanghai Medical College, Fudan University, Shanghai, People's Republic of China
- Central Laboratory, Huashan Hospital, Shanghai Medical College, Fudan University, Shanghai, People's Republic of China
| | - Tingting Hu
- Department of Laboratory Medicine, Huashan Hospital, Shanghai Medical College, Fudan University, Shanghai, People's Republic of China
| | - Xiaoye Gu
- Central Laboratory, Huashan Hospital, Shanghai Medical College, Fudan University, Shanghai, People's Republic of China
| | - Yuan Lu
- Department of Laboratory Medicine, Huashan Hospital, Shanghai Medical College, Fudan University, Shanghai, People's Republic of China
- * E-mail: (YL); (WL)
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Gao S, Wang HY, Malbon CC. AKAP12 and AKAP5 form higher-order hetero-oligomers. J Mol Signal 2011; 6:8. [PMID: 21831305 PMCID: PMC3170326 DOI: 10.1186/1750-2187-6-8] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2011] [Accepted: 08/10/2011] [Indexed: 01/12/2023] Open
Abstract
Background The family of A-kinase-anchoring proteins, AKAPs, constitutes a group of molecular scaffolds that act to catalyze dynamic interactions of protein kinase A, protein kinase C, tyrosine kinases, G-protein-coupled receptors and ion channels. AKAP5 (MW ~47 kDa) and AKAP12 (MW ~191 kDa) homo-oligomerize, but whether or not such AKAPs can hetero-oligomerize into supermolecular scaffolds of increased complexity is unknown. Results Affinity chromatography using immobilized AKAPs as "bait" demonstrates unequivocally that AKAP5 and AKAP12 do form minimally hetero-dimers. Steric-exclusion chromatography of AKAP5 and AKAP12 mixtures revealed the existence of very large, supermolecular complexes containing both AKAPs. Docking of AKAP5 to AKAP12 was increased 4-fold by beta-adrenergic agonist stimulation. Overexpression of AKAP12 was found to potentiate AKAP5-mediated Erk1/2 activation in response to stimulation with beta-adrenergic agonist. Conclusion AKAP5 and AKAP12 are capable of forming hetero-oligomeric supermolecular complexes that influence AKAP locale and function.
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Affiliation(s)
- Shujuan Gao
- Department of Pharmacology, Health Sciences Center, School of Medicine, State University of New York at Stony Brook, Stony Brook, NY 11794-8651 USA.
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12
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Gao S, Wang HY, Malbon CC. AKAP5 and AKAP12 Form Homo-oligomers. J Mol Signal 2011; 6:3. [PMID: 21554706 PMCID: PMC3113324 DOI: 10.1186/1750-2187-6-3] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2011] [Accepted: 05/09/2011] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND A-kinase-anchoring proteins, AKAPs, constitute a family of scaffolds that play an essential role in catalyzing the spatial-temporal, dynamic interactions of protein kinase A, protein kinase C, tyrosine kinases, G-protein-coupled receptors and ion channels. We studied AKAP5 (AKAP79; MW ~47 kDa) and AKAP12 (gravin, SSECKS; MW ~191 kDa) to probe if these AKAP scaffolds oligomerize. RESULTS In gel analysis and sodium-dodecyl sulfate denaturation, AKAP12 behaved with a MW of a homo-dimer. Only in the presence of the chaotropic agent 8 M urea did gel analysis reveal a monomeric form of AKAP12. By separation by steric-exclusion chromatography, AKAP12 migrates with MW of ~840 kDa, suggestive of higher-order complexes such as a tetramer. Interestingly, the N-(1-840) and C-(840-1782) terminal regions of AKAP12 themselves retained the ability to form dimers, suggesting that the structural basis for the dimerization is not restricted to a single "domain" found within the molecule. In either sodium dodecyl sulfate or urea, AKAP5 displayed a relative mobility of a monomer, but by co-immunoprecipitation in native state was shown to oligomerize. When subjected to steric-exclusion chromatography, AKAP5 forms higher-order complexes with MW ~220 kDa, suggestive of tetrameric assemblies. CONCLUSION Both AKAP5 and AKAP12 display the capacity to form supermolecular homo-oligomeric structures that likely influence the localization and function of these molecular scaffolds.
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Affiliation(s)
- Shujuan Gao
- Departments of Pharmacology, Heath Sciences Center, School of Medicine, State Univerdity of New York at Stony Brook, NY 11794-8651 USA
| | - Hsien-yu Wang
- Physiology & Biophysics, Health Sciences Center, School of Medicine, State Univerdity of New York at Stony Brook, NY 11794-8661 USA
| | - Craig C Malbon
- Departments of Pharmacology, Heath Sciences Center, School of Medicine, State Univerdity of New York at Stony Brook, NY 11794-8651 USA
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Streb JW, Long X, Lee TH, Sun Q, Kitchen CM, Georger MA, Slivano OJ, Blaner WS, Carr DW, Gelman IH, Miano JM. Retinoid-induced expression and activity of an immediate early tumor suppressor gene in vascular smooth muscle cells. PLoS One 2011; 6:e18538. [PMID: 21483686 PMCID: PMC3071728 DOI: 10.1371/journal.pone.0018538] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2010] [Accepted: 03/03/2011] [Indexed: 12/19/2022] Open
Abstract
Retinoids are used clinically to treat a number of hyper-proliferative disorders and have been shown in experimental animals to attenuate vascular occlusive diseases, presumably through nuclear receptors bound to retinoic acid response elements (RARE) located in target genes. Here, we show that natural or synthetic retinoids rapidly induce mRNA and protein expression of a specific isoform of A-Kinase Anchoring Protein 12 (AKAP12β) in cultured smooth muscle cells (SMC) as well as the intact vessel wall. Expression kinetics and actinomycin D studies indicate Akap12β is a retinoid-induced, immediate-early gene. Akap12β promoter analyses reveal a conserved RARE mildly induced with atRA in a region that exhibits hyper-acetylation. Immunofluorescence microscopy and protein kinase A (PKA) regulatory subunit overlay assays in SMC suggest a physical association between AKAP12β and PKA following retinoid treatment. Consistent with its designation as a tumor suppressor, inducible expression of AKAP12β attenuates SMC growth in vitro. Further, immunohistochemistry studies establish marked decreases in AKAP12 expression in experimentally-injured vessels of mice as well as atheromatous lesions in humans. Collectively, these results demonstrate a novel role for retinoids in the induction of an AKAP tumor suppressor that blocks vascular SMC growth thus providing new molecular insight into how retiniods may exert their anti-proliferative effects in the injured vessel wall.
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Affiliation(s)
- Jeffrey W. Streb
- Aab Cardiovascular Research Institute, University of Rochester School of Medicine and Dentistry, Rochester, New York, United States of America
| | - Xiaochun Long
- Aab Cardiovascular Research Institute, University of Rochester School of Medicine and Dentistry, Rochester, New York, United States of America
| | - Ting-Hein Lee
- Aab Cardiovascular Research Institute, University of Rochester School of Medicine and Dentistry, Rochester, New York, United States of America
| | - Qiang Sun
- Aab Cardiovascular Research Institute, University of Rochester School of Medicine and Dentistry, Rochester, New York, United States of America
| | - Chad M. Kitchen
- Aab Cardiovascular Research Institute, University of Rochester School of Medicine and Dentistry, Rochester, New York, United States of America
| | - Mary A. Georger
- Aab Cardiovascular Research Institute, University of Rochester School of Medicine and Dentistry, Rochester, New York, United States of America
| | - Orazio J. Slivano
- Aab Cardiovascular Research Institute, University of Rochester School of Medicine and Dentistry, Rochester, New York, United States of America
| | - William S. Blaner
- Department of Medicine, Columbia University, New York, New York, United States of America
| | - Daniel W. Carr
- Portland Veterans Affairs Medical Center, Portland, Oregon, United States of America
| | - Irwin H. Gelman
- Department of Cancer Genetics, Roswell Park Cancer Institute, Buffalo, New York, United States of America
| | - Joseph M. Miano
- Aab Cardiovascular Research Institute, University of Rochester School of Medicine and Dentistry, Rochester, New York, United States of America
- Department of Pathology and Laboratory Medicine, University of Rochester School of Medicine and Dentistry, Rochester, New York, United States of America
- * E-mail:
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14
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Suzuki T, Moriya K, Nagatoshi K, Ota Y, Ezure T, Ando E, Tsunasawa S, Utsumi T. Strategy for comprehensive identification of human N-myristoylated proteins using an insect cell-free protein synthesis system. Proteomics 2010; 10:1780-93. [PMID: 20213681 DOI: 10.1002/pmic.200900783] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
To establish a strategy for the comprehensive identification of human N-myristoylated proteins, the susceptibility of human cDNA clones to protein N-myristoylation was evaluated by metabolic labeling and MS analyses of proteins expressed in an insect cell-free protein synthesis system. One-hundred-and-forty-one cDNA clones with N-terminal Met-Gly motifs were selected as potential candidates from approximately 2000 Kazusa ORFeome project human cDNA clones, and their susceptibility to protein N-myristoylation was evaluated using fusion proteins, in which the N-terminal ten amino acid residues were fused to an epitope-tagged model protein. As a result, the products of 29 out of 141 cDNA clones were found to be effectively N-myristoylated. The metabolic labeling experiments both in an insect cell-free protein synthesis system and in the transfected COS-1 cells using full-length cDNA revealed that 27 out of 29 proteins were in fact N-myristoylated. Database searches with these 27 cDNA clones revealed that 18 out of 27 proteins are novel N-myristoylated proteins that have not been reported previously to be N-myristoylated, indicating that this strategy is useful for the comprehensive identification of human N-myristoylated proteins from human cDNA resources.
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Affiliation(s)
- Takashi Suzuki
- Clinical and Biotechnology Business Unit, Shimadzu Corporation, Kyoto, Japan
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15
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Nichols CB, Rossow CF, Navedo MF, Westenbroek RE, Catterall WA, Santana LF, McKnight GS. Sympathetic stimulation of adult cardiomyocytes requires association of AKAP5 with a subpopulation of L-type calcium channels. Circ Res 2010; 107:747-56. [PMID: 20671242 DOI: 10.1161/circresaha.109.216127] [Citation(s) in RCA: 132] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
RATIONALE Sympathetic stimulation of the heart increases the force of contraction and rate of ventricular relaxation by triggering protein kinase (PK)A-dependent phosphorylation of proteins that regulate intracellular calcium. We hypothesized that scaffolding of cAMP signaling complexes by AKAP5 is required for efficient sympathetic stimulation of calcium transients. OBJECTIVE We examined the function of AKAP5 in the β-adrenergic signaling cascade. METHODS AND RESULTS We used calcium imaging and electrophysiology to examine the sympathetic response of cardiomyocytes isolated from wild type and AKAP5 mutant animals. The β-adrenergic regulation of calcium transients and the phosphorylation of substrates involved in calcium handling were disrupted in AKAP5 knockout cardiomyocytes. The scaffolding protein, AKAP5 (also called AKAP150/79), targets adenylyl cyclase, PKA, and calcineurin to a caveolin 3-associated complex in ventricular myocytes that also binds a unique subpopulation of Ca(v)1.2 L-type calcium channels. Only the caveolin 3-associated Ca(v)1.2 channels are phosphorylated by PKA in response to sympathetic stimulation in wild-type heart. However, in the AKAP5 knockout heart, the organization of this signaling complex is disrupted, adenylyl cyclase 5/6 no longer associates with caveolin 3 in the T-tubules, and noncaveolin 3-associated calcium channels become phosphorylated after β-adrenergic stimulation, although this does not lead to an enhanced calcium transient. The signaling domain created by AKAP5 is also essential for the PKA-dependent phosphorylation of ryanodine receptors and phospholamban. CONCLUSIONS These findings identify an AKAP5-organized signaling module that is associated with caveolin 3 and is essential for sympathetic stimulation of the calcium transient in adult heart cells.
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Affiliation(s)
- C Blake Nichols
- Department of Pharmacology, University of Washington, Seattle, WA 98195, USA
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16
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Ku CY, Murtazina DA, Kim YS, Garfield RE, Sanborn BM. Changes in rat myometrial plasma membrane protein kinase A are confined to parturition. Reprod Sci 2010; 17:696-704. [PMID: 20457802 DOI: 10.1177/1933719110368869] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
We have previously shown that pregnant rat myometrial plasma membrane-associated cyclic adenosine monophosphate (cAMP)-dependent protein kinase A (PKA) decreases prior to delivery, coincident with a decline in the inhibitory effect of cAMP on contractant-stimulated parameters. We now find that rat myometrial membrane-associated PKA concentrations in early to mid-pregnancy are equivalent to those in cycling rats. Following the decline associated with parturition, membrane PKA recovers within 1 to 2 days postpartum. Treatment with the antiprogestin onapristone caused a decrease in myometrial membrane PKA catalytic and regulatory subunits compared to untreated controls by 12 hours. This coincided temporally with recently reported increases in electrical and contractile activity. In unilaterally pregnant rats, the decline in plasma membrane PKA was observed in both nonpregnant and pregnant horns but was more rapid in the pregnant horns. These data indicate that the myometrial plasma membrane PKA pattern before and during most of pregnancy is not consistent with progesterone exerting a primary influence on PKA membrane localization. Rather, the fall in membrane PKA associated with parturition may contribute to or be influenced by the increased contractile and electrical activity of labor that is a consequence of the loss of progesterone influence and is not absolutely dependent on the presence of fetuses.
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Affiliation(s)
- Chun-Ying Ku
- Department of Biomedical Sciences, Colorado State University, Fort Collins, CO 80523, USA
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17
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Tao J, Wang HY, Malbon CC. AKAR2-AKAP12 fusion protein "biosenses" dynamic phosphorylation and localization of a GPCR-based scaffold. J Mol Signal 2010; 5:3. [PMID: 20412577 PMCID: PMC2871262 DOI: 10.1186/1750-2187-5-3] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2010] [Accepted: 04/22/2010] [Indexed: 11/24/2022] Open
Abstract
Background The cAMP-dependent protein kinase A (PKA) plays a pivotal role in virtually all cells, there being a multitude of important target molecules that are substrates for PKA in cell signaling. The spatial-temporal dynamics of PKA activation in living cells has been made accessible by the development of clever biosensors that yield a FRET signal in response to the phosphorylation by PKA. AKAR2 is genetically encoded fluorescent probe that acts as a biosensor for PKA activation. AKAP12 is a scaffold that docks PKA, G-protein-coupled receptors, cell membrane negatively-charged phospholipids, and catalyzes receptor resensitization and recycling. In the current work, the AKAR2 biosensor was fused to the N-terminus of AKAP12 to evaluate its ability to function and report on dynamic phosphorylation of the AKAP12 scaffold. Results AKAR2-AKAP12 can be expressed in mammalian cells, is fully functional, and reveals the spatial-temporal activation of AKAP12 undergoing phosphorylation by PKA in response to beta-adrenergic activation in human epidermoid carcinoma A431 cells. Conclusion The dynamic phosphorylation of AKAP12 "biosensed" by AKAR2-AKAP12 reveals the scaffold in association with the cell membrane, undergoing rapid phosphorylation by PKA. The perinuclear, cytoplasmic accumulation of phosphorylated scaffold reflects the phosphorylated, PKA-activated form of AKAP12, which catalyzes the resensitization and recycling of desensitized, internalized G-protein-coupled receptors.
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Affiliation(s)
- Jiangchuan Tao
- Department of Pharmacology, School of Medicine, Heath Sciences Center, SUNY/Stony Brook, Stony Brook, NY 11794-8651, USA.
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18
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Zeke A, Lukács M, Lim WA, Reményi A. Scaffolds: interaction platforms for cellular signalling circuits. Trends Cell Biol 2009; 19:364-74. [PMID: 19651513 DOI: 10.1016/j.tcb.2009.05.007] [Citation(s) in RCA: 114] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2009] [Revised: 05/17/2009] [Accepted: 05/18/2009] [Indexed: 12/12/2022]
Abstract
Scaffold proteins influence cellular signalling by binding to multiple signalling enzymes, receptors or ion channels. Although normally devoid of catalytic activity, they have a big impact on controlling the flow of signalling information. By assembling signalling proteins into complexes, they play the part of signal processing hubs. As we learn more about the way signalling components are linked into natural signalling circuits, researchers are becoming interested in building non-natural signalling pathways to test our knowledge and/or to intentionally reprogram cellular behaviour. In this review, we discuss the role of scaffold proteins as efficient tools for assembling intracellular signalling complexes, both natural and artificial.
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Affiliation(s)
- András Zeke
- Department of Biochemistry, Eötvös Loránd University, Pázmány Péter sétány 1/C, H-1117 Budapest, Hungary
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Dai S, Hall DD, Hell JW. Supramolecular assemblies and localized regulation of voltage-gated ion channels. Physiol Rev 2009; 89:411-52. [PMID: 19342611 DOI: 10.1152/physrev.00029.2007] [Citation(s) in RCA: 264] [Impact Index Per Article: 17.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
This review addresses the localized regulation of voltage-gated ion channels by phosphorylation. Comprehensive data on channel regulation by associated protein kinases, phosphatases, and related regulatory proteins are mainly available for voltage-gated Ca2+ channels, which form the main focus of this review. Other voltage-gated ion channels and especially Kv7.1-3 (KCNQ1-3), the large- and small-conductance Ca2+-activated K+ channels BK and SK2, and the inward-rectifying K+ channels Kir3 have also been studied to quite some extent and will be included. Regulation of the L-type Ca2+ channel Cav1.2 by PKA has been studied most thoroughly as it underlies the cardiac fight-or-flight response. A prototypical Cav1.2 signaling complex containing the beta2 adrenergic receptor, the heterotrimeric G protein Gs, adenylyl cyclase, and PKA has been identified that supports highly localized via cAMP. The type 2 ryanodine receptor as well as AMPA- and NMDA-type glutamate receptors are in close proximity to Cav1.2 in cardiomyocytes and neurons, respectively, yet independently anchor PKA, CaMKII, and the serine/threonine phosphatases PP1, PP2A, and PP2B, as is discussed in detail. Descriptions of the structural and functional aspects of the interactions of PKA, PKC, CaMKII, Src, and various phosphatases with Cav1.2 will include comparisons with analogous interactions with other channels such as the ryanodine receptor or ionotropic glutamate receptors. Regulation of Na+ and K+ channel phosphorylation complexes will be discussed in separate papers. This review is thus intended for readers interested in ion channel regulation or in localization of kinases, phosphatases, and their upstream regulators.
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Affiliation(s)
- Shuiping Dai
- Department of Pharmacology, University of Iowa, Iowa City, IA 52242-1109, USA
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20
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A-kinase anchoring in dendritic cells is required for antigen presentation. PLoS One 2009; 4:e4807. [PMID: 19277197 PMCID: PMC2652104 DOI: 10.1371/journal.pone.0004807] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2008] [Accepted: 02/10/2009] [Indexed: 11/25/2022] Open
Abstract
Background Dendritic cells (DC) are the most potent antigen presenting cells (APC) of the immune system. Prostaglandin E2, cyclic AMP, and protein kinase A (PKA) have all been shown to regulate DC maturation and activity. In other cells, the ability of these molecules to convey their signals has been shown to be dependent on A-kinase anchoring proteins (AKAPs). Here we present evidence for the existence and functional importance of AKAPs in human DC. Methodology/Principal Findings Using immunofluorescence and/or western analyses we identify AKAP79, AKAP149, AKAP95, AKAP LBC and Ezrin. We also demonstrate by western analysis that expression of AKAP79, AKAP149 and RII are upregulated with DC differentiation and maturation. We establish the functional importance of PKA anchoring in multiple aspects of DC biology using the anchoring inhibitor peptides Ht31 and AKAP-IS. Incubation of protein or peptide antigen loaded DC with Ht31 or AKAP-IS results in a 30–50% decrease in antigen presentation as measured by IFN-γ production from antigen specific CD4+ T cells. Incubation of LPS treated DC with Ht31 results in 80% inhibition of TNF-α and IL-10 production. Ht31 slightly decreases the expression of CD18 and CD11a and CD11b, slightly increases the basal expression of CD83, dramatically decreases the LPS stimulated expression of CD40, CD80 and CD83, and significantly increases the expression of the chemokine receptor CCR7. Conclusions These experiments represent the first evidence for the functional importance of PKA anchoring in multiple aspects of DC biology.
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Tao J, Malbon CC. G-protein-coupled receptor-associated A-kinase anchoring proteins AKAP5 and AKAP12: differential signaling to MAPK and GPCR recycling. J Mol Signal 2008; 3:19. [PMID: 19055733 PMCID: PMC2621157 DOI: 10.1186/1750-2187-3-19] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2008] [Accepted: 12/02/2008] [Indexed: 11/10/2022] Open
Abstract
Background A-kinase Anchoring Protein AKAP5 and AKAP12 both dock to the β2-adrenergic receptor, the former constitutively, the latter dynamically in response to activation of the receptor with agonist. Results In the current work we analyze the ability of each AKAP to contribute to two downstream signaling events, the activation of mitogen-activate protein kinase and the resensitization/recycling of the internalized, desensitized β2-adrenergic receptor to the cell membrane. Although both AKAP share a large number of docking partners in common (e.g., β2-adrenergic receptor, protein kinases A and C, protein phosphatase-2B, and negatively-charged membrane phospholipids), AKAP5 and AKAP12 are shown to segregate with respect to activation of Erk1,2 and to resensitization/recycling of β2-adrenergic receptor. A431 cells were found to highly express AKAP12, but little of AKAP5. HEK293 cells, in contrast, were found to highly express AKAP5, but little of AKAP12. Suppression of the expression of AKAP5 in either A431 cells or HEK293 cells leads to loss of the ability of the β2-adrenergic receptor to activate Erk1,2. Suppression of the expression of AKAP12 in either cell line leads to loss of the ability of these cells to resensitize the β2-adrenergic receptor. Conclusion Knock-down experiments of endogenous AKAP 5 and AKAP12 in two cell lines used commonly to study β2-adrenergic receptor signaling clearly discriminate between the activation of mitogen-activated protein kinase (a downstream read-out solely mediated by AKAP5) and receptor recycling (a downstream read-out solely mediated by AKAP12).
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Affiliation(s)
- Jiangchuan Tao
- Department of Pharmacology, School of Medicine, Health Sciences Center, State University of New York at Stony Brook, Stony Brook, NY 11794-8651, USA.
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22
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Weiser DC, St Julien KR, Lang JS, Kimelman D. Cell shape regulation by Gravin requires N-terminal membrane effector domains. Biochem Biophys Res Commun 2008; 375:512-516. [PMID: 18725198 DOI: 10.1016/j.bbrc.2008.08.063] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2008] [Accepted: 08/05/2008] [Indexed: 12/11/2022]
Abstract
Gravin (AKAP12, SSeCKS) is a scaffolding protein that acts as a potent inhibitor of tumor metastasis in vivo and in vitro, and regulates morphogenesis during vertebrate gastrulation. Despite being implicated in many cellular processes, surprisingly little is known about the mechanism by which Gravin elicits cell shape changes. In this work, we use in vitro cell spreading assays to demonstrate that the Gravin N-terminus containing the three MARCKS-like basic regions (BRs) is necessary and sufficient to regulate cell shape in vitro. We show that the conserved phosphorylation sites in the BRs are essential for their function in these assays. We further demonstrate that the Gravin BRs are necessary for in vivo function during gastrulation in zebrafish. Together, these results provide an important step forward in understanding the mechanism of Gravin function in cell shape regulation and provide valuable insight into how Gravin acts as a cytoskeletal regulator.
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Affiliation(s)
- Douglas C Weiser
- Department of Biochemistry, University of Washington, Seattle WA 98195
| | | | - James S Lang
- Department of Biochemistry, University of Washington, Seattle WA 98195
| | - David Kimelman
- Department of Biochemistry, University of Washington, Seattle WA 98195
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23
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Lygren B, Taskén K. The potential use of AKAP18δ as a drug target in heart failure patients. Expert Opin Biol Ther 2008; 8:1099-108. [DOI: 10.1517/14712598.8.8.1099] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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Xin W, Tran TM, Richter W, Clark RB, Rich TC. Roles of GRK and PDE4 activities in the regulation of beta2 adrenergic signaling. ACTA ACUST UNITED AC 2008; 131:349-64. [PMID: 18347080 PMCID: PMC2279169 DOI: 10.1085/jgp.200709881] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
An important focus in cell biology is understanding how different feedback mechanisms regulate G protein-coupled receptor systems. Toward this end we investigated the regulation of endogenous beta(2) adrenergic receptors (beta2ARs) and phosphodiesterases (PDEs) by measuring cAMP signals in single HEK-293 cells. We monitored cAMP signals using genetically encoded cyclic nucleotide-gated (CNG) channels. This high resolution approach allowed us to make several observations. (a) Exposure of cells to 1 muM isoproterenol triggered transient increases in cAMP levels near the plasma membrane. Pretreatment of cells with 10 muM rolipram, a PDE4 inhibitor, prevented the decline in the isoproterenol-induced cAMP signals. (b) 1 muM isoproterenol triggered a sustained, twofold increase in phosphodiesterase type 4 (PDE4) activity. (c) The decline in isoproterenol-dependent cAMP levels was not significantly altered by including 20 nM PKI, a PKA inhibitor, or 3 muM 59-74E, a GRK inhibitor, in the pipette solution; however, the decline in the cAMP levels was prevented when both PKI and 59-74E were included in the pipette solution. (d) After an initial 5-min stimulation with isoproterenol and a 5-min washout, little or no recovery of the signal was observed during a second 5-min stimulation with isoproterenol. (e) The amplitude of the signal in response to the second isoproterenol stimulation was not altered when PKI was included in the pipette solution, but was significantly increased when 59-74E was included. Taken together, these data indicate that either GRK-mediated desensitization of beta2ARs or PKA-mediated stimulation of PDE4 activity is sufficient to cause declines in cAMP signals. In addition, the data indicate that GRK-mediated desensitization is primarily responsible for a sustained suppression of beta2AR signaling. To better understand the interplay between receptor desensitization and PDE4 activity in controlling cAMP signals, we developed a mathematical model of this system. Simulations of cAMP signals using this model are consistent with the experimental data and demonstrate the importance of receptor levels, receptor desensitization, basal adenylyl cyclase activity, and regulation of PDE activity in controlling cAMP signals, and hence, on the overall sensitivity of the system.
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Affiliation(s)
- Wenkuan Xin
- Department of Pharmacology, College of Medicine and Center for Lung Biology, University of South Alabama, Mobile, AL 36688, USA
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25
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Hendriks-Balk MC, Peters SLM, Michel MC, Alewijnse AE. Regulation of G protein-coupled receptor signalling: focus on the cardiovascular system and regulator of G protein signalling proteins. Eur J Pharmacol 2008; 585:278-91. [PMID: 18410914 DOI: 10.1016/j.ejphar.2008.02.088] [Citation(s) in RCA: 71] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2008] [Revised: 01/18/2008] [Accepted: 02/06/2008] [Indexed: 11/17/2022]
Abstract
G protein-coupled receptors (GPCRs) are involved in many biological processes. Therefore, GPCR function is tightly controlled both at receptor level and at the level of signalling components. Well-known mechanisms by which GPCR function can be regulated comprise desensitization/resensitization processes and GPCR up- and downregulation. GPCR function can also be regulated by several proteins that directly interact with the receptor and thereby modulate receptor activity. An additional mechanism by which receptor signalling is regulated involves an emerging class of proteins, the so-called regulators of G protein signalling (RGS). In this review we will describe some of these control mechanisms in more detail with some specific examples in the cardiovascular system. In addition, we will provide an overview on RGS proteins and the involvement of RGS proteins in cardiovascular function.
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Affiliation(s)
- Mariëlle C Hendriks-Balk
- Department Pharmacology and Pharmacotherapy, Academic Medical Center, Amsterdam, The Netherlands
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26
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Penn RB. Embracing emerging paradigms of G protein-coupled receptor agonism and signaling to address airway smooth muscle pathobiology in asthma. Naunyn Schmiedebergs Arch Pharmacol 2008; 378:149-69. [PMID: 18278482 DOI: 10.1007/s00210-008-0263-1] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2007] [Accepted: 01/15/2008] [Indexed: 01/04/2023]
Abstract
G protein-coupled receptors (GPCRs) regulate numerous airway cell functions, and signaling events transduced by GPCRs are important in both asthma pathogenesis and therapy. Indeed, most asthma therapies target GPCRs either directly or indirectly. Within recent years, our understating of how GPCRs signal and are regulated has changed significantly as new concepts have emerged and traditional ideas have evolved. In this review, we discuss current concepts regarding constitutive GPCR activity and receptor agonism, functional selectivity, compartmentalized signaling, and GPCR desensitization. We further discuss the relevance of these ideas to asthma and asthma therapy, while emphasizing their potential application to the GPCR signaling in airway smooth muscle that regulates airway patency and thus disease severity.
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Affiliation(s)
- Raymond B Penn
- Department of Internal Medicine, Wake Forest University Health Sciences Center, Winston-Salem, NC 27157, USA.
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27
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Appert-Collin A, Baisamy L, Diviani D. Regulation of g protein-coupled receptor signaling by a-kinase anchoring proteins. J Recept Signal Transduct Res 2007; 26:631-46. [PMID: 17118802 DOI: 10.1080/10799890600923211] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Specificity of transduction events is controlled at the molecular level by scaffold, anchoring, and adaptor proteins, which position signaling enzymes at proper subcellular localization. This allows their efficient catalytic activation and accurate substrate selection. A-kinase anchoring proteins (AKAPs) are group of functionally related proteins that compartmentalize the cAMP-dependent protein kinase (PKA) and other signaling enyzmes at precise subcellular sites in close proximity to their physiological substrate(s) and favor specific phosphorylation events. Recent evidence suggests that AKAP transduction complexes play a key role in regulating G protein-coupled receptor (GPCR) signaling. Regulation can occur at multiple levels because AKAPs have been shown both to directly modulate GPCR function and to act as downstream effectors of GPCR signaling. In this minireview, we focus on the molecular mechanisms through which AKAP-signaling complexes modulate GPCR transduction cascades.
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Affiliation(s)
- Aline Appert-Collin
- Département de Pharmacologie et de Toxicologie, Faculté de Médecine, Lausanne, Switzerland
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Tao J, Wang HY, Malbon CC. Src Docks to A-kinase Anchoring Protein Gravin, Regulating β2-Adrenergic Receptor Resensitization and Recycling. J Biol Chem 2007; 282:6597-608. [PMID: 17200117 DOI: 10.1074/jbc.m608927200] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Gravin (AKAP12) is a membrane-associated scaffold that provides docking for protein kinases, phosphatases, and adaptor molecules obligate for resensitization and recycling of beta(2)-adrenergic receptors. Gravin binds to the cell membrane in a Ca(2+)-sensitive manner and to receptors through well characterized protein-protein interactions. Although the interaction of serine/threonine, cyclic AMP-dependent protein kinase with protein kinase A-anchoring proteins is well described and involves a kinase regulatory subunit binding domain in the C terminus of these proteins, far less is known about tyrosine kinase docking to members of this family of scaffolds. The non-receptor tyrosine kinase Src regulates resensitization of beta(2)-adrenergic receptors and docks to gravin. Gravin displays nine proline-rich domains distributed throughout the molecule. One class I ligand for Src homology domain 3 docking, found in the N terminus ((10)RXPXXP(15)) of gravin, is shown to bind Src. Binding of Src to gravin activates the intrinsic tyrosine kinase of Src. Mutagenesis/deletion of the class I ligand (P15A,P16A) on the N terminus of gravin abolishes both the docking of Src to gravin as well as the receptor resensitization and recycling catalyzed by gravin. The Src-binding peptide-(1-51) of gravin behaves as a dominant-negative for AKAP gravin regulation of receptor resensitization/recycling. The tyrosine kinase Src plays an essential role in the AKAP gravin-mediated receptor resensitization and recycling, an essential aspect of receptor biology.
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Affiliation(s)
- Jiangchuan Tao
- Department of Pharmacology, State University of New York, Stony Brook, New York 11794-8651, USA
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29
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Bengrine A, Li J, Awayda MS. The A-kinase anchoring protein 15 regulates feedback inhibition of the epithelial Na+ channel. FASEB J 2007; 21:1189-201. [PMID: 17244820 DOI: 10.1096/fj.06-6046com] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
Protein kinase A anchoring proteins or AKAPs regulate the activity of many ion channels. Protein kinase A (PKA) is a well-recognized target of AKAPs, with other kinases now emerging as additional targets. We examined the roles of epithelial-expressed AKAPs in regulating the epithelial Na+ channel (ENaC). Experiments used heterologous expression with AKAP15, AKAP-KL, and AKAP79 in Xenopus oocytes. Experiments were carried out under high and low Na+ conditions, as Na+ loading is known to affect the baseline activity of ENaC in a PKC-dependent mechanism. ENaC activity was unaffected by AKAP79 and AKAP-KL expression. However, oocytes coexpressing AKAP15 exhibited an 80% and 91% reduction in the amiloride-sensitive, whole-cell conductance in high and low Na+ conditions, respectively. The reduced channel activity was unaffected by PKA activation or inhibition, indicating a PKA-independent mechanism. Expression with a membrane-targeting domain, mutant form of AKAP15 (AKAP15m) prevented the decrease of ENaC activity, but only under low Na+ conditions. In high sodium conditions, coexpression with AKAP15m led to an increase of ENaC activity to levels similar to those observed under low Na+. These results indicate that membrane-associated AKAP15 reduces ENaC activity whereas the cytoplasmically associated one may participate in the channel's feedback inhibition by intracellular Na+, a process known to involve PKC. This hypothesis was further confirmed in coexpression experiments, which demonstrated functional and physical interaction between AKAP15 and PKCalpha. We propose that AKAP15 regulates ENaC via a novel PKA-independent pathway.
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Affiliation(s)
- Abderrahmane Bengrine
- Department of Physiology and Biophysics, SUNY at Buffalo, 3435 Main St., Buffalo, NY 14214, USA
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30
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Tao J, Shumay E, McLaughlin S, Wang HY, Malbon CC. Regulation of AKAP-Membrane Interactions by Calcium. J Biol Chem 2006; 281:23932-44. [PMID: 16762919 DOI: 10.1074/jbc.m601813200] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The AKAP gravin is a scaffold for protein kinases, phosphatases, and adaptor molecules obligate for resensitization and recycling of beta2-adrenergic receptors. Gravin binds to the receptor through well characterized protein-protein interactions. These interactions are facilitated approximately 1000-fold when gravin is anchored to the cytoplasmic leaflet of the plasma membrane. Although the N-terminal region (approximately 550 residues) is highly negatively charged and probably natively unfolded, it could anchor gravin to the inner leaflet through hydrophobic insertion of its N-terminal myristate and electrostatic binding of three short positively charged domains (PCDs). Loss of the site of N-myristoylation was found to affect neither AKAP macroscopic localization nor AKAP function. Synthetic peptides corresponding to PCD1-3 bound in vitro to unilamellar phospholipid vesicles with high affinity, a binding reversed by calmodulin in the presence of Ca2+. In vivo gravin localization is regulated by intracellular Ca2+, a function mapping to the N terminus of the protein harboring PCD1, PCD2, and PCD3. Mutation of any two PCDs eliminates membrane association of the non-myristoylated gravin, the sensitivity to Ca2+/calmodulin, and the ability of this scaffold to catalyze receptor resensitization and recycling.
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Affiliation(s)
- Jiangchuan Tao
- Department of Pharmacology, School of Medicine, Heath Sciences Center, State University of New York, Stony Brook, New York 11794-8651, USA
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Abstract
All cells respond to metabolic stress. However, a variety of specialized cells, commonly referred to as O2-sensing cells, are acutely sensitive to relatively small changes in PO2. Within a variety of organisms such O2-sensing cells have evolved as vital homeostatic mechanisms that monitor O2 supply and alter respiratory and circulatory function, as well as the capacity of the blood to transport O2. Thereby, arterial PO2 may be maintained within physiological limits. In mammals, for example, two key tissues that contribute to this process are the pulmonary arteries and the carotid bodies. Constriction of pulmonary arteries by hypoxia optimizes ventilation-perfusion matching in the lung, whilst carotid body excitation by hypoxia initiates corrective changes in breathing patterns via increased sensory afferent discharge to the brain stem. Despite extensive investigation, the precise mechanism(s) by which hypoxia mediates these responses has remained elusive. It is clear, however, that hypoxia inhibits mitochondrial function in O2-sensing cells over a range of PO2 that has no such effect on other cell types. This raised the possibility that AMP-activated protein kinase might function to couple mitochondrial oxidative phosphorylation to Ca2+ signalling mechanisms in O2-sensing cells and thereby underpin pulmonary artery constriction and carotid body excitation by hypoxia. Our recent investigations have provided significant evidence in support of this view.
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Affiliation(s)
- A Mark Evans
- Division of Biomedical Sciences, School of Biology, Bute Building, University of St Andrews, St Andrews, Fife KY16 9TS, UK.
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Proceedings of the first International Meeting on Anchored cAMP Signaling Pathways, Biomedical Campus, Berlin-Buch, Germany, 15-16 October 2005. Eur J Cell Biol 2006; 85:581-697. [PMID: 16647785 DOI: 10.1016/j.ejcb.2006.03.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022] Open
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