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Redpath G, Deo N. Serotonin: an overlooked regulator of endocytosis and endosomal sorting? Biol Open 2022; 11:bio059057. [PMID: 35076063 PMCID: PMC8801889 DOI: 10.1242/bio.059057] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2021] [Accepted: 12/09/2021] [Indexed: 12/23/2022] Open
Abstract
Serotonin is a neurotransmitter and a hormone that is typically associated with regulating our mood. However, the serotonin transporter and receptors are expressed throughout the body, highlighting the much broader, systemic role of serotonin in regulating human physiology. A substantial body of data strongly implicates serotonin as a fundamental regulator of endocytosis and endocytic sorting. Serotonin has the potential to enhance endocytosis through three distinct mechanisms - serotonin signalling, serotonylation and insertion into the plasma membrane - although the interplay and relationship between these mechanisms has not yet been explored. Endocytosis is central to the cellular response to the extracellular environment, controlling receptor distribution on the plasma membrane to modulate signalling, neurotransmitter release and uptake, circulating protein and lipid cargo uptake, and amino acid internalisation for cell proliferation. Uncovering the range of cellular and physiological circumstances in which serotonin regulates endocytosis is of great interest for our understanding of how serotonin regulates mood, and also the fundamental understanding of endocytosis and its regulation throughout the body. This article has an associated Future Leader to Watch interview with the first author of the paper.
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Affiliation(s)
- Gregory Redpath
- EMBL Australia Node in Single Molecule Science, School of Medical Sciences and the ARC Centre of Excellence in Advanced Molecular Imaging, University of New South Wales, Sydney 2052, Australia
| | - Nikita Deo
- Department of Biochemistry, University of Otago, Dunedin 9016, New Zealand
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2
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Kato Y, Ochiai A, Seki Y, Morimoto T, Oizumi H, Ohbuchi K, Mizoguchi K, Yamamoto M, Sakagami H, Miyamoto Y, Yamauchi J. Phospholipase D and phosphatidylinositol-4-phosphate 5-kinase 1 are involved in the regulation of oligodendrocyte morphological differentiation. Exp Cell Res 2021; 405:112654. [PMID: 34044015 DOI: 10.1016/j.yexcr.2021.112654] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2021] [Revised: 05/08/2021] [Accepted: 05/12/2021] [Indexed: 12/30/2022]
Abstract
Oligodendroglial cells (oligodendrocytes) differentiate to form the myelin that wraps neuronal axons in the central nervous system (CNS). This myelin sheath supports the propagation of saltatory conduction and protects axons from physical stresses. When oligodendrocytes do not normally differentiate to myelinate axons, their key functions as oligodendrocytes in the CNS are severely impaired. The molecular mechanics that control differentiation still remain to be clarified. Arf6 belongs to the small GTPase family and is known to be a positive regulator of oligodendrocyte differentiation. Here, we show that the phospholipase D (PLD) and phosphatidylinositol-4-phosphate 5-kinase 1 (PIP5K1) molecules, the major effectors of Arf6, are involved in the regulation of oligodendrocyte differentiation. Knockdown of PLD1 or PIP5K type 1γ (PIP5K1C) by their respective specific siRNAs in mouse oligodendroglial FBD-102b cells inhibited morphological differentiation into structures bearing myelin-like processes; this finding is consistent with the concurrent changes in expression of differentiation and myelin marker proteins. Treatment with VU0155069 or UNC3230, specific inhibitors of PLD and PIP5K1, respectively, blunted morphological differentiation and decreased expression of myelin and differentiation marker proteins. Similar results have been obtained in studies using primary oligodendrocytes. These results suggest that the major Arf6 effector molecules PLD and PIP5K1 are among the molecules involved in the regulation of morphological differentiation in oligodendrocytes prior to myelination.
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Affiliation(s)
- Yukino Kato
- Laboratory of Molecular Neurology, Tokyo University of Pharmacy and Life Sciences, Hachioji, Tokyo, 192-0392, Japan
| | - Arisa Ochiai
- Laboratory of Molecular Neurology, Tokyo University of Pharmacy and Life Sciences, Hachioji, Tokyo, 192-0392, Japan
| | - Yoichi Seki
- Laboratory of Molecular Neurology, Tokyo University of Pharmacy and Life Sciences, Hachioji, Tokyo, 192-0392, Japan
| | - Takako Morimoto
- Laboratory of Molecular Neurology, Tokyo University of Pharmacy and Life Sciences, Hachioji, Tokyo, 192-0392, Japan
| | - Hiroaki Oizumi
- Tsumura Research Laboratories, Tsumura & Co., Inashiki, Ibaraki, 200-1192, Japan
| | - Katsuya Ohbuchi
- Tsumura Research Laboratories, Tsumura & Co., Inashiki, Ibaraki, 200-1192, Japan
| | - Kazushige Mizoguchi
- Tsumura Research Laboratories, Tsumura & Co., Inashiki, Ibaraki, 200-1192, Japan
| | - Masahiro Yamamoto
- Tsumura Research Laboratories, Tsumura & Co., Inashiki, Ibaraki, 200-1192, Japan
| | - Hiroyuki Sakagami
- Department of Anatomy, Kitasato University School of Medicine, Sagamihara, Kanagawa, 252-0374, Japan
| | - Yuki Miyamoto
- Laboratory of Molecular Neurology, Tokyo University of Pharmacy and Life Sciences, Hachioji, Tokyo, 192-0392, Japan; Department of Pharmacology, National Research Institute for Child Health and Development, Setagaya, Tokyo, 157-8535, Japan
| | - Junji Yamauchi
- Laboratory of Molecular Neurology, Tokyo University of Pharmacy and Life Sciences, Hachioji, Tokyo, 192-0392, Japan; Department of Pharmacology, National Research Institute for Child Health and Development, Setagaya, Tokyo, 157-8535, Japan.
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3
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Arai M, Sera T, Hasegawa T, Kudo S. Spatial and temporal translocation of PKCα in single endothelial cell in response to mechanical stimulus. Exp Cell Res 2018; 367:205-215. [DOI: 10.1016/j.yexcr.2018.03.038] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/25/2017] [Revised: 03/28/2018] [Accepted: 03/29/2018] [Indexed: 12/14/2022]
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4
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Friday SC, Fox DA. Phospholipase D enzymes facilitate IL-17- and TNFα-induced expression of proinflammatory genes in rheumatoid arthritis synovial fibroblasts (RASF). Immunol Lett 2016; 174:9-18. [DOI: 10.1016/j.imlet.2016.04.001] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2016] [Revised: 04/01/2016] [Accepted: 04/01/2016] [Indexed: 11/30/2022]
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5
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Shaiken TE, Opekun AR. Dissecting the cell to nucleus, perinucleus and cytosol. Sci Rep 2014; 4:4923. [PMID: 24815916 PMCID: PMC4017230 DOI: 10.1038/srep04923] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2014] [Accepted: 04/22/2014] [Indexed: 12/25/2022] Open
Abstract
Cells have been described under the microscope as organelles containing cytoplasm and the nucleus. However, an unnoted structure exists between the cytoplasm and the nucleoplasm of eukaryotic cells. In addition to the nuclear envelope, there exists a perinuclear region (PNR or perinucleus) with unknown composition and function. Until now, an investigation of the role of the perinucleus has been restricted by the absence of a PNR isolation method. This manuscript describes a perinucleus isolation technique on the basis of its unique compact organization. The perinucleus was found to contain approximately 15 to 18% of the total proteins of the mammalian cell, almost half of the proteins of nuclei. Using four different normal and cancer cell lines, it was shown that the composition of PNR is highly dynamic. Application of the method showed that translocation of the p53 tumor-suppressor protein to the perinucleus in immortalized MEF cells is correlated with the translocation of p53-stabilizing protein, nucleophosmin (B23), to the PNR. Herein, the concept of the perinuclear region is advanced as a formal, identifiable structure. The roles of the perinucleus in maintaining genome integrity, regulation of gene expression and understanding of malignant transformation are discussed.
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Affiliation(s)
- Tattym E Shaiken
- Department of Molecular and Cellular Oncology, University of Texas M. D. Anderson Cancer Center, Houston, TX 77030, USA
| | - Antone R Opekun
- Departments of Medicine & Pediatrics G.I. & S.A.H.S. Baylor College of Medicine-McNair Faculty Center A10.019 One Baylor Plaza (GI Medicine MS901), Houston, Texas 77030, USA
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6
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El Osta M, Liu M, Adada M, Senkal CE, Idkowiak-Baldys J, Obeid LM, Clarke CJ, Hannun YA. Sustained PKCβII activity confers oncogenic properties in a phospholipase D- and mTOR-dependent manner. FASEB J 2013; 28:495-505. [PMID: 24121461 DOI: 10.1096/fj.13-230557] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Protein kinase C (PKC) is a family of serine/threonine kinases implicated in a variety of physiological processes. We have shown previously that sustained activation of the classical PKCα and PKCβII induces their phospholipase D (PLD)-dependent internalization and translocation to a subset of the recycling endosomes defined by the presence of PKC and PLD (the pericentrion), which results in significant differences in phosphorylation of PKC substrates. Here, we have investigated the biological consequences of sustained PKC activity and the involvement of PLD in this process. We find that sustained activation of PKC results in activation of the mammalian target of rapamycin (mTOR)/S6 kinase pathway in a PLD- and endocytosis-dependent manner, with both pharmacologic inhibitors and siRNA implicating the PLD2 isoform. Notably, dysregulated overexpression of PKCβII in A549 lung cancer cells was necessary for the enhanced proliferation and migration of these cancer cells. Inhibition of PKCβII with enzastaurin reduced A549 cell proliferation by >60% (48 h) and migration by >50%. These biological effects also required both PLD activity and mTOR function, with both the PLD inhibitor FIPI and rapamycin reducing cell growth by >50%. Reciprocally, forced overexpression of wild-type PKCβII, but not an F666D mutant that cannot interact with PLD, was sufficient to enhance cell growth and increase migration of noncancerous HEK cells; indeed, both properties were almost doubled when compared to vector control and PKC-F666D-overexpressing cells. Notably, this condition was also dependent on both PLD and mTOR activity. In summary, these data define a PKC-driven oncogenic signaling pathway that requires both PLD and mTOR, and suggest that inhibitors of PLD or mTOR would be beneficial in cancers where PKC overexpression is a contributing or driving factor.
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Affiliation(s)
- Mohamad El Osta
- 2Stony Brook Cancer Center and Department of Medicine, Stony Brook University, 100 Nicolls Rd., Stony Brook, NY 11794, USA.
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Kolesnikov YS, Nokhrina KP, Kretynin SV, Volotovski ID, Martinec J, Romanov GA, Kravets VS. Molecular structure of phospholipase D and regulatory mechanisms of its activity in plant and animal cells. BIOCHEMISTRY (MOSCOW) 2012; 77:1-14. [DOI: 10.1134/s0006297912010014] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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8
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El-Osta MA, Idkowiak-Baldys J, Hannun YA. Delayed phosphorylation of classical protein kinase C (PKC) substrates requires PKC internalization and formation of the pericentrion in a phospholipase D (PLD)-dependent manner. J Biol Chem 2011; 286:19340-53. [PMID: 21478146 DOI: 10.1074/jbc.m110.152330] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
It was previously demonstrated that sustained activation (30-60 min) of protein kinase C (PKC) results in translocation of PKC α and βII to the pericentrion, a dynamic subset of the recycling compartment whose formation is dependent on PKC and phospholipase D (PLD). Here we investigated whether the formation of the pericentrion modulates the ability of PKC to phosphorylate substrates, especially if it reduces substrate phosphorylation by sequestering PKC. Surprisingly, using an antibody that detects phosphosubstrates of classical PKCs, the results showed that the majority of PKC phosphosubstrates are phosphorylated with delayed kinetics, correlating with the time frame of PKC translocation to the pericentrion. Substrate phosphorylation was blocked by PLD inhibitors and was not observed in response to activation of a PKC βII mutant (F663D) that is defective in interaction with PLD and in internalization. Phosphorylation was also inhibited by blocking clathrin-dependent endocytosis, demonstrating a requirement for endocytosis for the PKC-dependent major phosphorylation effects. Serotonin receptor activation by serotonin showed a similar response to phorbol 12-myristate 13-acetate, implicating a potential role of delayed kinetics in G protein-coupled receptor signaling. Evaluation of candidate substrates revealed that the phosphorylation of the PKC substrate p70S6K kinase behaved in a similar manner. Gradient-based fractionation revealed that the majority of these PKC substrates reside within the pericentrion-enriched fractions and not in the plasma membrane. Finally, proteomic analysis of the pericentrion-enriched fractions revealed several proteins as known PKC substrates and/or proteins involved in endocytic trafficking. These results reveal an important role for PKC internalization and for the pericentrion as key determinants/amplifiers of PKC action.
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Affiliation(s)
- Mohamad A El-Osta
- Department of Biochemistry and Molecular Biology, Medical University of South Carolina, Charleston, South Carolina 29425, USA
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Wang H, Kazanietz MG. p23/Tmp21 differentially targets the Rac-GAP beta2-chimaerin and protein kinase C via their C1 domains. Mol Biol Cell 2010; 21:1398-408. [PMID: 20164256 PMCID: PMC2854097 DOI: 10.1091/mbc.e09-08-0735] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
The ER/Golgi protein p23/Tmp21 acts as a C1 domain-docking protein that mediates perinuclear translocation of β-chimaerin. C1 domains from PKC isozymes can also interact with p23/Tmp21. Our study highlights the relevance of C1 domains in protein-protein interactions in addition to their well-established lipid-binding properties. The C1 domains in protein kinase C (PKC) isozymes and other signaling molecules are responsible for binding the lipid second messenger diacylglycerol and phorbol esters, and for mediating translocation to membranes. Previous studies revealed that the C1 domain in α- and β-chimaerins, diacylglycerol-regulated Rac-GAPs, interacts with the endoplasmic reticulum/Golgi protein p23/Tmp21. Here, we found that p23/Tmp21 acts as a C1 domain-docking protein that mediates perinuclear translocation of β2-chimaerin. Glu227 and Leu248 in the β2-chimaerin C1 domain are crucial for binding p23/Tmp21 and perinuclear targeting. Interestingly, isolated C1 domains from individual PKC isozymes differentially interact with p23/Tmp21. For PKCε, it interacts with p23/Tmp21 specifically via its C1b domain; however, this association is lost in response to phorbol esters. These results demonstrate that p23/Tmp21 acts as an anchor that distinctively modulates compartmentalization of C1 domain-containing proteins, and it plays an essential role in β2-chimaerin relocalization. Our study also highlights the relevance of C1 domains in protein–protein interactions in addition to their well-established lipid-binding properties.
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Affiliation(s)
- Hongbin Wang
- Department of Pharmacology, University of Pennsylvania School of Medicine, Philadelphia, PA 19104-6160
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10
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Idkowiak-Baldys J, Baldys A, Raymond JR, Hannun YA. Sustained receptor stimulation leads to sequestration of recycling endosomes in a classical protein kinase C- and phospholipase D-dependent manner. J Biol Chem 2009; 284:22322-22331. [PMID: 19525236 PMCID: PMC2755955 DOI: 10.1074/jbc.m109.026765] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2009] [Indexed: 11/06/2022] Open
Abstract
Considerable insight has been garnered on initial mechanisms of endocytosis of plasma membrane proteins and their subsequent trafficking through the endosomal compartment. It is also well established that ligand stimulation of many plasma membrane receptors leads to their internalization. However, stimulus-induced regulation of endosomal trafficking has not received much attention. In previous studies, we showed that sustained stimulation of protein kinase C (PKC) with phorbol esters led to sequestration of recycling endosomes in a juxtanuclear region. In this study, we investigated whether G-protein-coupled receptors that activate PKC exerted effects on endosomal trafficking. Stimulation of cells with serotonin (5-hydroxytryptamine (5-HT)) led to sequestration of the 5-HT receptor (5-HT2AR) into a Rab11-positive juxtanuclear compartment. This sequestration coincided with translocation of PKC as shown by confocal microscopy. Mechanistically the observed sequestration of 5-HT2AR was shown to require continuous PKC activity because it was inhibited by pretreatment with classical PKC inhibitor Gö6976 and could be reversed by posttreatment with this inhibitor. In addition, classical PKC autophosphorylation was necessary for receptor sequestration. Moreover inhibition of phospholipase D (PLD) activity and inhibition of PLD1 and PLD2 using dominant negative constructs also prevented this process. Functionally this sequestration did not affect receptor desensitization or resensitization as measured by intracellular calcium increase. However, the PKC- and PLD-dependent sequestration of receptors resulted in co-sequestration of other plasma membrane proteins and receptors as shown for epidermal growth factor receptor and protease activated receptor-1. This led to heterologous desensitization of those receptors and diverted their cellular fate by protecting them from agonist-induced degradation. Taken together, these results demonstrate a novel role for sustained receptor stimulation in regulation of intracellular trafficking, and this process requires sustained stimulation of PKC and PLD.
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Affiliation(s)
| | - Aleksander Baldys
- Division of Nephrology, Department of Medicine, Medical University of South Carolina, Charleston, South Carolina 29425 and
- Medical and Research Services, Ralph H. Johnson Veterans Affairs Medical Center, Charleston, South Carolina 29401
| | - John R. Raymond
- Division of Nephrology, Department of Medicine, Medical University of South Carolina, Charleston, South Carolina 29425 and
- Medical and Research Services, Ralph H. Johnson Veterans Affairs Medical Center, Charleston, South Carolina 29401
| | - Yusuf A. Hannun
- From the Department of Biochemistry and Molecular Biology and
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12
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French AD, Fiori JL, Camilli TC, Leotlela PD, O'Connell MP, Frank BP, Subaran S, Indig FE, Taub DD, Weeraratna AT. PKC and PKA phosphorylation affect the subcellular localization of claudin-1 in melanoma cells. Int J Med Sci 2009; 6:93-101. [PMID: 19305641 PMCID: PMC2658888 DOI: 10.7150/ijms.6.93] [Citation(s) in RCA: 86] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/27/2009] [Accepted: 03/12/2009] [Indexed: 12/13/2022] Open
Abstract
Cytoplasmic expression of claudin-1 in metastatic melanoma cells correlates to increased migration, and increased secretion of MMP-2 in a PKC dependent manner, whereas claudin-1 nuclear expression is found in benign nevi. Melanoma cells were transfected with a vector expressing CLDN-1 fused to a nuclear localization signal (NLS). Despite significant nuclear localization of claudin-1, there was still transport of claudin-1 to the cytoplasm. Phorbol ester treatment of cells transfected with NLS-claudin-1 resulted in an exclusion of claudin-1 from the nucleus, despite the NLS. To ascertain whether PKC or PKA were involved in this translocation, we mutated the putative phosphorylation sites within the protein. We found that mutating the PKC phosphorylation sites to mimic a non-phosphorylated state did not cause a shift of claudin-1 to the nucleus of the cells, but mutating the PKA sites did. Mutations of either site to mimic constitutive phosphorylation resulted in cytoplasmic claudin-1 expression. Stable claudin-1 transfectants containing non-phosphorylatable PKA sites exhibited decreased motility. These data imply that subcellular localization of claudin-1 can be controlled by phosphorylation, dicating effects on metastatic capacity.
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Affiliation(s)
- Amanda D French
- Laboratory of Immunology, National Institute on Aging, Baltimore, MD 21124, USA
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13
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Abstract
Protein kinase C (PKC) isoforms comprise a family of lipid-activated enzymes that have been implicated in a wide range of cellular functions. PKCs are modular enzymes comprised of a regulatory domain (that contains the membrane-targeting motifs that respond to lipid cofactors, and in the case of some PKCs calcium) and a relatively conserved catalytic domain that binds ATP and substrates. These enzymes are coexpressed and respond to similar stimulatory agonists in many cell types. However, there is growing evidence that individual PKC isoforms subserve unique (and in some cases opposing) functions in cells, at least in part as a result of isoform-specific subcellular compartmentalization patterns, protein-protein interactions, and posttranslational modifications that influence catalytic function. This review focuses on the structural basis for differences in lipid cofactor responsiveness for individual PKC isoforms, the regulatory phosphorylations that control the normal maturation, activation, signaling function, and downregulation of these enzymes, and the intra-/intermolecular interactions that control PKC isoform activation and subcellular targeting in cells. A detailed understanding of the unique molecular features that underlie isoform-specific posttranslational modification patterns, protein-protein interactions, and subcellular targeting (i.e., that impart functional specificity) should provide the basis for the design of novel PKC isoform-specific activator or inhibitor compounds that can achieve therapeutically useful changes in PKC signaling in cells.
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Affiliation(s)
- Susan F Steinberg
- Department of Pharmacology, College of Physicians and Surgeons, Columbia University, New York, New York 10032, USA.
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14
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Vorland M, Holmsen H. Phospholipase D in human platelets: presence of isoenzymes and participation of autocrine stimulation during thrombin activation. Platelets 2008; 19:211-24. [PMID: 18432522 DOI: 10.1080/09537100701777329] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Abstract
Phospholipase D (PLD), which hydrolyzes phosphatidylcholine to phosphatidic acid (PA) and choline, is present in human platelets. Thrombin and other agonists have been shown to activate PLD but the precise mechanisms of activation and PLDs role in platelet activation remains unclear. We measured thrombin-stimulated PLD activity in platelets as formation of phosphatidylethanol. Since no specific PLD inhibitors exist, we investigated possible roles for PLD in platelets by correlating PLD activity with platelet responses such as thrombin-mediated secretion and F-actin formation (part of platelet shape change). Extracellular Ca2+ potentiated thrombin-stimulated PLD, but did not stimulate PLD in the absence of thrombin. Thrombin-induced PLD activity was enhanced by secreted ADP and binding of fibrinogen to its receptors. In contrast to others, we also found a basal PLD activity. Comparison of time courses and dose responses of platelets with PLD showed many points of correlation between PLD activation and lysosomal secretion and F-actin formation. The finding of different PLD activities suggested that different PLD isoenzymes exist in platelets as reported for other cells. Here we present evidence for the presence of both PLD1 and PLD2 in platelets by use of specific antibodies with immunoblotting and immunohistochemistry. Both isoforms were randomly localized in resting platelets, but became rapidly translocated to the proximity of the plasma membrane upon thrombin stimulation, thus indicating a role for PLD in platelet activation.
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Affiliation(s)
- M Vorland
- Department of Biomedicine, Faculty of Medicine, University of Bergen, Norway.
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Takahashi H, Namiki H. Mechanism of membrane redistribution of protein kinase C by its ATP-competitive inhibitors. Biochem J 2007; 405:331-40. [PMID: 17373912 PMCID: PMC1904528 DOI: 10.1042/bj20070299] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
ATP-competitive inhibitors of PKC (protein kinase C) such as the bisindolylmaleimide GF 109203X, which interact with the ATP-binding site in the PKC molecule, have also been shown to affect several redistribution events of PKC. However, the reason why these inhibitors affect the redistribution is still controversial. In the present study, using immunoblot analysis and GFP (green fluorescent protein)-tagged PKC, we showed that, at commonly used concentrations, these ATP-competitive inhibitors alone induced redistribution of DAG (diacylglycerol)-sensitive PKCalpha, PKCbetaII, PKCdelta and PKCepsilon, but not atypical PKCzeta, to the endomembrane or the plasma membrane. Studies with deletion and point mutants showed that the DAG-sensitive C1 domain of PKC was required for membrane redistribution by these inhibitors. Furthermore, membrane redistribution was prevented by the aminosteroid PLC (phospholipase C) inhibitor U-73122, although an ATP-competitive inhibitor had no significant effect on acute DAG generation. Immunoblot analysis showed that an ATP-competitive inhibitor enhanced cell-permeable DAG analogue- or phorbol-ester-induced translocation of endogenous PKC. Furthermore, these inhibitors also enhanced [3H]phorbol 12,13-dibutyrate binding to the cytosolic fractions from PKCalpha-GFP-overexpressing cells. These results clearly demonstrate that ATP-competitive inhibitors cause redistribution of DAG-sensitive PKCs to membranes containing endogenous DAG by altering the DAG sensitivity of PKC and support the idea that the inhibitors destabilize the closed conformation of PKC and make the C1 domain accessible to DAG. Most importantly, our findings provide novel insights for the interpretation of studies using ATP-competitive inhibitors, and, especially, suggest caution about the interpretation of the relationship between the redistribution and kinase activity of PKC.
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Affiliation(s)
- Hideyuki Takahashi
- Department of Biology, School of Education, Waseda University, Shinjuku-ku, Tokyo 169-0051, Japan.
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16
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Kitatani K, Idkowiak-Baldys J, Hannun YA. Mechanism of inhibition of sequestration of protein kinase C alpha/betaII by ceramide. Roles of ceramide-activated protein phosphatases and phosphorylation/dephosphorylation of protein kinase C alpha/betaII on threonine 638/641. J Biol Chem 2007; 282:20647-56. [PMID: 17504762 DOI: 10.1074/jbc.m609162200] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Sustained activation of protein kinase C (PKC) isoenzymes alpha and betaII leads to their translocation to a perinuclear region and to the formation of the pericentrion, a PKC-dependent subset of recycling endosomes. In MCF-7 human breast cancer cells, the action of the PKC activator 4beta-phorbol-12-myristate-13-acetate (PMA) evokes ceramide formation, which in turn prevents PKCalpha/betaII translocation to the pericentrion. In this study we investigated the mechanisms by which ceramide negatively regulates this translocation of PKCalpha/betaII. Upon PMA treatment, HEK-293 cells displayed dual phosphorylation of PKCalpha/betaII at carboxyl-terminal sites (Thr-638/641 and Ser-657/660), whereas in MCF-7 cells PKCalpha/betaII were phosphorylated at Ser-657/660 but not Thr-638/641. Inhibition of ceramide synthesis by fumonisin B1 overcame the defect in PKC phosphorylation and restored translocation of PKCalpha/betaII to the pericentrion. To determine the involvement of ceramide-activated protein phosphatases in PKC regulation, we employed small interference RNA to silence individual Ser/Thr protein phosphatases. Knockdown of isoforms alpha or beta of the catalytic subunits of protein phosphatase 1 not only increased phosphorylation of PKCalpha/betaII at Thr-638/641 but also restored PKCbetaII translocation to the pericentrion. Mutagenesis approaches in HEK-293 cells revealed that mutation of either Thr-641 or Ser-660 to Ala in PKCbetaII abolished sequestration of PKC, implying the indispensable roles of phosphorylation of PKCalpha/betaII at those sites for their translocation to the pericentrion. Reciprocally, a point mutation of Thr-641 to Glu, which mimics phosphorylation, in PKCbetaII overcame the inhibitory effects of ceramide on PKC translocation in PMA-stimulated MCF-7 cells. Therefore, the results demonstrate a novel role for carboxyl-terminal phosphorylation of PKCalpha/betaII in the translocation of PKC to the pericentrion, and they disclose specific regulation of PKC autophosphorylation by ceramide through the activation of specific isoforms of protein phosphatase 1.
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Affiliation(s)
- Kazuyuki Kitatani
- Department of Biochemistry and Molecular Biology, Medical University of South Carolina, 173 Ashley Avenue, Charleston, SC 29425, USA
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Wang J, Wang N, Xie J, Walton SC, McKown RL, Raab RW, Ma P, Beck SL, Coffman GL, Hussaini IM, Laurie GW. Restricted epithelial proliferation by lacritin via PKCalpha-dependent NFAT and mTOR pathways. ACTA ACUST UNITED AC 2006; 174:689-700. [PMID: 16923831 PMCID: PMC1761701 DOI: 10.1083/jcb.200605140] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Renewal of nongermative epithelia is poorly understood. The novel mitogen "lacritin" is apically secreted by several nongermative epithelia. We tested 17 different cell types and discovered that lacritin is preferentially mitogenic or prosecretory for those types that normally contact lacritin during its glandular outward flow. Mitogenesis is dependent on lacritin's C-terminal domain, which can form an alpha-helix with a hydrophobic face, as per VEGF's and PTHLP's respective dimerization or receptor-binding domain. Lacritin targets downstream NFATC1 and mTOR. The use of inhibitors or siRNA suggests that lacritin mitogenic signaling involves Galpha(i) or Galpha(o)-PKCalpha-PLC-Ca2+-calcineurin-NFATC1 and Galpha(i) or Galpha(o)-PKCalpha-PLC-phospholipase D (PLD)-mTOR in a bell-shaped, dose-dependent manner requiring the Ca2+ sensor STIM1, but not TRPC1. This pathway suggests the placement of transiently dephosphorylated and perinuclear Golgi-translocated PKCalpha upstream of both Ca2+ mobilization and PLD activation in a complex with PLCgamma2. Outward flow of lacritin from secretory cells through ducts may generate a proliferative/secretory field as a different unit of cellular renewal in nongermative epithelia where luminal structures predominate.
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Affiliation(s)
- Jiahu Wang
- Department of Cell Biology, University of Virginia, Charlottesville, VA 22904, USA
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Idkowiak-Baldys J, Becker KP, Kitatani K, Hannun YA. Dynamic sequestration of the recycling compartment by classical protein kinase C. J Biol Chem 2006; 281:22321-22331. [PMID: 16751194 DOI: 10.1074/jbc.m512540200] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
It has been previously shown that upon sustained stimulation (30-60 min) with phorbol esters, protein kinase C (PKC) alpha and betaII become sequestered in a juxtanuclear region, the pericentrion. The activation of PKC also results in sequestration of transferrin, suggesting a role for PKC in regulating endocytosis and sequestration of recycling components. In this work we characterize the pericentrion as a PKC-dependent subset of the recycling compartment. We demonstrate that upon sustained stimulation of PKC, both protein (CD59, caveolin) and possibly also lipid (Bodipy-GM1) cargo become sequestered in a PKC-dependent manner. This sequestration displayed a strict temperature requirement and was inhibited below 32 degrees C. Treatment of cells with phorbol myristate acetate for 60 min led to the formation of a distinct membrane structure. PKC sequestration and pericentrion formation were blocked by hypertonic sucrose as well as by potassium depletion (inhibitors of clathrin-dependent endocytosis) but not by nystatin or filipin, which inhibit clathrin-independent pathways. Interestingly, it was also observed that some molecules that internalize through clathrin-independent pathways (CD59, Bodipy-GM1, caveolin) also sequestered to the pericentrion upon sustained PKC activation, suggesting that PKC acted distal to the site of internalization of endocytic cargo. Together these results suggest that PKC regulates sequestration of recycling molecules into this compartment, the pericentrion.
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Affiliation(s)
- Jolanta Idkowiak-Baldys
- Department of Biochemistry and Molecular Biology, Medical University of South Carolina, Charleston, South Carolina 29425
| | - Kevin P Becker
- Department of Biochemistry and Molecular Biology, Medical University of South Carolina, Charleston, South Carolina 29425
| | - Kazuyuki Kitatani
- Department of Biochemistry and Molecular Biology, Medical University of South Carolina, Charleston, South Carolina 29425
| | - Yusuf A Hannun
- Department of Biochemistry and Molecular Biology, Medical University of South Carolina, Charleston, South Carolina 29425.
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Hu T, Exton JH. A point mutation at phenylalanine 663 abolishes protein kinase Cα’s ability to translocate to the perinuclear region and activate phospholipase D1. Biochem Biophys Res Commun 2005; 333:750-3. [PMID: 15963950 DOI: 10.1016/j.bbrc.2005.05.184] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2005] [Accepted: 05/19/2005] [Indexed: 11/17/2022]
Abstract
Previous research showed that protein kinase C alpha (PKC alpha) translocated to the perinuclear region and activated phospholipase D1, but the mechanism involved was not clear. Here, we provide evidence that Phe 663 (the 10th amino acid from C-terminus) of PKC alpha is essential for its translocation. A point mutation (F663D) completely blocked PKC alpha's binding to and activation of phospholipase D1. Further studies showed that deletion of the C-terminal nine amino acids of PKC alpha did not alter its translocation to the perinuclear region but deletion of the C-terminal 10 amino acids and the F663D mutation abolished this translocation. The F663D mutant was found to be resistant to dephosphorylation, which might account for its inability to translocate to the perinuclear region and activate PLD1, since dephosphorylation of PKC alpha is required for its relocation from plasma membrane to the perinuclear region.
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Affiliation(s)
- Tianhui Hu
- Howard Hughes Medical Institute and Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, TN 37232, USA
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20
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Stubbs CD, Botchway SW, Slater SJ, Parker AW. The use of time-resolved fluorescence imaging in the study of protein kinase C localisation in cells. BMC Cell Biol 2005; 6:22. [PMID: 15854225 PMCID: PMC1131895 DOI: 10.1186/1471-2121-6-22] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2004] [Accepted: 04/26/2005] [Indexed: 01/28/2023] Open
Abstract
Background Two-photon-excitation fluorescence lifetime imaging (2P-FLIM) was used to investigate the association of protein kinase C alpha (PKCα) with caveolin in CHO cells. PKCα is found widely in the cytoplasm and nucleus in most cells. Upon activation, as a result of increased intracellular Ca2+ and production of DAG, through G-protein coupled-phospholipase C signalling, PKC translocates to a variety of regions in the cell where it phosphorylates and interacts with many signalling pathways. Due to its wide distribution, discerning a particular interaction from others within the cell is extremely difficult Results Fluorescence energy transfer (FRET), between GFP-PKCα and DsRed-caveolin, was used to investigate the interaction between caveolin and PKC, an aspect of signalling that is poorly understood. Using 2P-FLIM measurements, the lifetime of GFP was found to decrease (quench) in certain regions of the cell from ~2.2 ns to ~1.5 ns when the GFP and DsRed were sufficiently close for FRET to occur. This only occurred when intracellular Ca2+ increased or in the presence of phorbol ester, and was an indication of PKC and caveolin co-localisation under these conditions. In the case of phorbol ester stimulated PKC translocation, as commonly used to model PKC activation, three PKC areas could be delineated. These included PKCα that was not associated with caveolin in the nucleus and cytoplasm, PKCα associated with caveolin in the cytoplasm/perinuclear regions and probably in endosomes, and PKC in the peripheral regions of the cell, possibly indirectly interacting with caveolin. Conclusion Based on the extent of lifetime quenching observed, the results are consistent with a direct interaction between PKCα and caveolin in the endosomes, and possibly an indirect interaction in the peripheral regions of the cell. The results show that 2P-FLIM-FRET imaging offers an approach that can provide information not only confirming the occurrence of specific protein-protein interactions but where they occur within the cell.
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Affiliation(s)
- Christopher D Stubbs
- Department of Pathology and Cell Biology, Thomas Jefferson University, Philadelphia PA 19107 USA
- The Central Laser Facility, Rutherford Appleton Laboratory, CCLRC, Chilton, OX11 OQX UK
| | - Stanley W Botchway
- The Central Laser Facility, Rutherford Appleton Laboratory, CCLRC, Chilton, OX11 OQX UK
| | - Simon J Slater
- Department of Pathology and Cell Biology, Thomas Jefferson University, Philadelphia PA 19107 USA
| | - Anthony W Parker
- The Central Laser Facility, Rutherford Appleton Laboratory, CCLRC, Chilton, OX11 OQX UK
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Hu T, Exton JH. 1-Butanol interferes with phospholipase D1 and protein kinase Calpha association and inhibits phospholipase D1 basal activity. Biochem Biophys Res Commun 2005; 327:1047-51. [PMID: 15652502 DOI: 10.1016/j.bbrc.2004.12.117] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2004] [Indexed: 11/16/2022]
Abstract
1-Butanol is commonly used as a substrate for phospholipase D (PLD) activity measurement. Surprisingly we found that, in the presence of 30 mM 1-butanol (standard PLD assay conditions), PLD1 activity in COS-7 cells was lost after incubation for 2 min. In contrast, in the presence of the protein kinase C (PKC) inhibitor staurosporine or dominant negative PKCalpha D481E, the activity was sustained for at least 30min. The binding between PLD1 and PKCalpha was also lost after 2 min incubation with 30 mM 1-butanol while staurosporine and D481E maintained the binding. 1-Butanol at 2 mM did not inhibit PLD1 basal activity or PLD1 binding to PKCalpha, and staurosporine and PKCalpha D481E produced a constant increase in PLD1 basal activity of 2-fold. These results indicate that 1-butanol is inhibitory to PLD1 activity by reducing its association with PKCalpha, and that the concentration of 1-butanol is an important consideration in assaying basal PLD1 activity.
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Affiliation(s)
- Tianhui Hu
- Department of Molecular Physiology and Biophysics, Howard Hughes Medical Institute, Vanderbilt University School of Medicine, Nashville, TN 37232, USA
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Becker KP, Kitatani K, Idkowiak-Baldys J, Bielawski J, Hannun YA. Selective Inhibition of Juxtanuclear Translocation of Protein Kinase C βII by a Negative Feedback Mechanism Involving Ceramide Formed from the Salvage Pathway. J Biol Chem 2005; 280:2606-12. [PMID: 15546881 DOI: 10.1074/jbc.m409066200] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
In a previous study, we showed that protein kinase C betaII (PKC betaII) translocated to a novel juxtanuclear compartment as observed in several cell types (Becker, K. P., and Hannun, Y. A. (2003) J. Biol. Chem. 278, 52747-52754). In this study, we noted the absence of this translocation in MCF-7 breast cancer cells, and we examined the mechanisms underlying this selectivity of response. We show that sustained stimulation of PKC betaII with 4beta-phorbol 12-myristate 13-acetate (PMA) resulted in accumulation of ceramide in MCF-7 cells but not in those cells that showed juxtanuclear translocation of PKC betaII. Addition of exogenous ceramides or formation of endogenous ceramide by the action of bacterial sphingomyelinase prevented PMA-induced translocation of PKC betaII in HEK 293 cells. On the other hand, inhibition of ceramide accumulation with fumonisin B1 restored the ability of PMA to induce translocation of PKC betaII in MCF-7 cells. Taken together, the results showed that endogenous ceramide is both necessary and sufficient for preventing juxtanuclear translocation of PKC betaII in response to PMA. Investigation of the mechanisms of ceramide generation in response to PMA revealed that PMA activated the salvage pathway of ceramide formation and not the de novo pathway. This conclusion was based on the following: 1) the ability of fumonisin B1 but not myriocin to inhibit ceramide formation, 2) the ability of PMA to induce increases in palmitate-labeled ceramide only under chase labeling but not acute pulse labeling, 3) the induction of the levels of sphingosine but not dihydrosphingosine in response to PMA, and 4) induction of sphingomyelin hydrolysis in response to PMA. Together, these results define a novel pathway of regulated formation of ceramide, the salvage pathway, and they define a role for this pathway in regulating juxtanuclear translocation of PKC betaII.
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Affiliation(s)
- Kevin P Becker
- Department of Biochemistry and Molecular Biology, Medical University of South Carolina, Charleston, South Carolina 29425, USA
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Stensman H, Raghunath A, Larsson C. Autophosphorylation Suppresses Whereas Kinase Inhibition Augments the Translocation of Protein Kinase Cα in Response to Diacylglycerol. J Biol Chem 2004; 279:40576-83. [PMID: 15277524 DOI: 10.1074/jbc.m405560200] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
We have seen that protein kinase Calpha (PKCalpha) is transiently translocated to the plasma membrane by carbachol stimulation of neuroblastoma cells. This is induced by the Ca2+ increase, and PKCalpha does not respond to diacylglycerol (DAG). The unresponsiveness is dependent on structures in the catalytic domain of PKCalpha. This study was designed to investigate if and how the kinase activity and autophosphorylation are involved in regulating the translocation. PKCalpha enhanced green fluorescent protein translocation was studied in living neuroblastoma cells by confocal microscopy. Carbachol stimulation induced a transient translocation of PKCalpha to the plasma membrane and a sustained translocation of kinase-dead PKCalpha. In cells treated with the PKC inhibitor GF109203X, wild-type PKCalpha also showed a sustained translocation. The same effects were seen with PKCbetaI, PKCbetaII, and PKCdelta. Only kinase-dead and not wild-type PKCalpha translocated in response to 1,2-dioctanoylglycerol. To examine whether autophosphorylation regulates relocation to the cytosol, the autophosphorylation sites in PKCalpha were mutated to glutamate, to mimic phosphorylation, or alanine, to mimic the non-phosphorylated protein. After stimulation with carbachol, glutamate mutants behaved like wild-type PKCalpha, whereas alanine mutants behaved like kinase-dead PKCalpha. When the alanine mutants were treated with 1,2-dioctanoylglycerol, all cells showed a sustained translocation of the protein. However, neither carbachol nor GF109203X had any major effects on the level of autophosphorylation, and GF109203X potentiated the translocation of the glutamate mutants. We, therefore, hypothesize that 1) autophosphorylation of PKCalpha limits its sensitivity to DAG and 2) that kinase inhibitors augment the DAG sensitivity of PKCalpha, perhaps by destabilizing the closed conformation.
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Affiliation(s)
- Helena Stensman
- Lund University, Molecular Medicine, Entrance 78, 3rd Floor, Malmö University Hospital, 205 02 Malmö, Sweden
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