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Muñoz-Saez E, de Munck E, Arahuetes RM, Solas MT, Martínez AM, Miguel BG. β-N-methylamino-L-alanine induces changes in both GSK3 and TDP-43 in human neuroblastoma. J Toxicol Sci 2013; 38:425-30. [PMID: 23665941 DOI: 10.2131/jts.38.425] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
β-N-methylamino-L-alanine (L-BMAA) is a neurotoxic amino acid produced by most cyanobacteria, which are extensively distributed in different environments all over the world. L-BMAA has been linked to a variety of neurodegenerative diseases. This work aims to analyze the toxicological action of L-BMAA related to alterations observed in different neurodegenerative illness as Alzheimer disease and amyotrophic lateral sclerosis. Our results demonstrate that neuroblastoma cells treated with L-BMAA show an increase in glycogen synthase kinase 3 β (GSk3β) and induce accumulation of TAR DNA-binding protein 43 (TDP-43) truncated forms (C-terminal fragments), phosphorylated and high molecular weight forms of TDP-43, that appears frequently in some neurodegenerative diseases.
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Affiliation(s)
- Emma Muñoz-Saez
- Departamento de Bioquímica y Biología Molecular I, Universidad Complutense de Madrid, Spain
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2
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Xie Z, Jiang Y, Liao EY, Chen Y, Pennypacker SD, Peng J, Chang SM. PIKE mediates EGFR proliferative signaling in squamous cell carcinoma cells. Oncogene 2012; 31:5090-8. [PMID: 22349826 DOI: 10.1038/onc.2012.10] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2011] [Accepted: 12/30/2011] [Indexed: 11/08/2022]
Abstract
One of the key drivers for squamous cell carcinoma (SCC) proliferation is activation of the epidermal growth factor receptor (EGFR), a known proto-oncogene. However, the mechanism of EGFR-dependent SCC proliferation remains unclear. Our previous studies indicate that epidermal growth factor (EGF)-induced SCC cell proliferation requires the SH3 domain of phospholipase C-γ1 (PLC-γ1), but not its catalytic activity. The SH3 domain of PLC-γ1 is known to activate the short form of nuclear phosphatidylinositol 3-kinase enhancer (PIKE) that enhances the activity of nuclear class Ia phosphatidylinositol 3-kinase (PI3K) required for proliferation. However, PIKE has been described for more than a decade to be present exclusively in neuronal cells. In the present study, we found that PIKE was highly expressed in malignant human keratinocytes (SCC4 and SCC12B2) but had low expression in normal human keratinocytes. Immunohistochemical analysis showed strong nuclear staining of PIKE in human epidermal and tongue SCC specimens but little staining in the adjacent non-cancerous epithelium. Treatment of SCC4 cells with EGF-induced translocation of PLC-γ1 to the nucleus and binding of PLC-γ1 to the nuclear PIKE. Knockdown of PLC-γ1 or PIKE blocked EGF-induced activation of class Ia PI3K and protein kinase C-ζ and phosphorylation of nucleolin in the nucleus as well as EGF-induced SCC cell proliferation. However, inhibition of the catalytic activity of PLC-γ1 had little effect. These data suggest that PIKE has a critical role in EGF-induced SCC cell proliferation and may function as a proto-oncogene in SCC.
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Affiliation(s)
- Z Xie
- Institute of Metabolism and Endocrinology, The Second Xiangya Hospital, Central South University, Changsha, Hunan, China.
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3
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Cosentino-Gomes D, Rocco-Machado N, Meyer-Fernandes JR. Cell signaling through protein kinase C oxidation and activation. Int J Mol Sci 2012; 13:10697-10721. [PMID: 23109817 PMCID: PMC3472709 DOI: 10.3390/ijms130910697] [Citation(s) in RCA: 171] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2012] [Revised: 08/02/2012] [Accepted: 08/13/2012] [Indexed: 01/15/2023] Open
Abstract
Due to the growing importance of cellular signaling mediated by reactive oxygen species (ROS), proteins that are reversibly modulated by these reactant molecules are of high interest. In this context, protein kinases and phosphatases, which act coordinately in the regulation of signal transduction through the phosphorylation and dephosphorylation of target proteins, have been described to be key elements in ROS-mediated signaling events. The major mechanism by which these proteins may be modified by oxidation involves the presence of key redox-sensitive cysteine residues. Protein kinase C (PKC) is involved in a variety of cellular signaling pathways. These proteins have been shown to contain a unique structural feature that is susceptible to oxidative modification. A large number of scientific studies have highlighted the importance of ROS as a second messenger in numerous cellular processes, including cell proliferation, gene expression, adhesion, differentiation, senescence, and apoptosis. In this context, the goal of this review is to discuss the mechanisms by which PKCs are modulated by ROS and how these processes are involved in the cellular response.
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Affiliation(s)
- Daniela Cosentino-Gomes
- Institute of Medical Biochemistry, Federal University of Rio de Janeiro (UFRJ), CCS, Bloco H, Cidade Universitária, Ilha do Fundão, 21941-590, Rio de Janeiro, RJ, Brazil; E-Mails: (N.R.-M.); (J.R.M.-F.)
- Institute of National Science and Technology of Structural Biology and Bioimage (INCTBEB), CCS, Bloco H, Cidade Universitária, Ilha do Fundão, 21941-590, Rio de Janeiro, RJ, Brazil
- Author to whom correspondence should be addressed; E-Mail: ; Tel.: +55-21-2562-6781; Fax: +55-21-2270-8647
| | - Nathália Rocco-Machado
- Institute of Medical Biochemistry, Federal University of Rio de Janeiro (UFRJ), CCS, Bloco H, Cidade Universitária, Ilha do Fundão, 21941-590, Rio de Janeiro, RJ, Brazil; E-Mails: (N.R.-M.); (J.R.M.-F.)
- Institute of National Science and Technology of Structural Biology and Bioimage (INCTBEB), CCS, Bloco H, Cidade Universitária, Ilha do Fundão, 21941-590, Rio de Janeiro, RJ, Brazil
| | - José Roberto Meyer-Fernandes
- Institute of Medical Biochemistry, Federal University of Rio de Janeiro (UFRJ), CCS, Bloco H, Cidade Universitária, Ilha do Fundão, 21941-590, Rio de Janeiro, RJ, Brazil; E-Mails: (N.R.-M.); (J.R.M.-F.)
- Institute of National Science and Technology of Structural Biology and Bioimage (INCTBEB), CCS, Bloco H, Cidade Universitária, Ilha do Fundão, 21941-590, Rio de Janeiro, RJ, Brazil
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4
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Role of protein kinase C and mitochondrial permeability transition pore in the neuroprotective effect of ceramide in ischemia-induced cell death. FEBS Lett 2010; 585:99-103. [PMID: 21081127 DOI: 10.1016/j.febslet.2010.11.015] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2010] [Revised: 11/08/2010] [Accepted: 11/09/2010] [Indexed: 12/30/2022]
Abstract
In this study, we investigated the role of protein kinase C (PKC) and mitochondrial permeability transition pore (mPTP) on the effect of ceramide in an in vitro model of ischemia in SH-SY5Y neuroblastoma cells. In ischemic cell viability studies, a dual effect of ceramide was observed, depending on ceramide concentration. PKC isoforms are involved in the protective effect of low concentrations of ceramide. During ischemia, ceramide treatment leads to an increase in the formation of reactive oxygen species (ROS), which induces a controlled opening of mPTP. This fact prevents mitochondrial Ca(2+) overload, which is clearly protective.
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5
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Agudo-López A, Miguel BG, Fernández I, Martínez AM. Involvement of mitochondria on neuroprotective effect of sphingosine-1-phosphate in cell death in an in vitro model of brain ischemia. Neurosci Lett 2010; 470:130-3. [PMID: 20045720 DOI: 10.1016/j.neulet.2009.12.070] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2009] [Revised: 12/22/2009] [Accepted: 12/28/2009] [Indexed: 01/16/2023]
Abstract
Sphingosine-1-phosphate (S1P) has been demonstrated to be an important regulator of cell death and survival. Although it has been suggested that the sphingolipid may act as a neuroprotector in the cell apoptosis induced by traumatic brain injury, the mechanisms involved in this action are unknown. In this study, the relationship between S1P and neuroprotective effect was studied in an in vitro model of ischemia, maintaining SH-SY5Y human neuroblastoma cells under oxygen-glucose deprivation (OGD). When cells were treated with 1 microM S1P simultaneously with OGD and recovery, cell viability increases in a dose-response manner. S1P treatment reduces significantly both necrosis and apoptosis cell death. On the other hand, the treatment with specific PKC epsilon (V1-2), prevents S1P protective effect of OGD/recovery-induced necrosis. Moreover, S1P treatment provokes the translocation of PKC epsilon to the mitochondria. From these results, it is reasonable to assume that S1P protection from necrosis is mediated by PKC epsilon. We also studied the action of S1P on mitochondrial inner membrane potential and mitochondrial Ca(2+) levels during ischemia. In this regard, we must point out that S1P treatment reduces the OGD-induced membrane depolarization and also reduces the increase of Ca(2+) in mitochondria during OGD. Results also indicate that mitochondria from OGD treated cells have significantly less ability to resist swelling on Ca(2+) loading than those obtained in presence of oxygen and glucose. Nevertheless, when S1P was added, this resistance increases considerably. These findings suggest that S1P may have a potential role as a neuroprotective agent in brain injury.
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Affiliation(s)
- Alba Agudo-López
- Departamento de Bioquímica y Biología Molecular I, Facultad de Química, Universidad Complutense de Madrid, E-28040 Madrid, Spain
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6
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Yao H, Hwang JW, Moscat J, Diaz-Meco MT, Leitges M, Kishore N, Li X, Rahman I. Protein kinase C zeta mediates cigarette smoke/aldehyde- and lipopolysaccharide-induced lung inflammation and histone modifications. J Biol Chem 2009; 285:5405-16. [PMID: 20007975 DOI: 10.1074/jbc.m109.041418] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Atypical protein kinase C (PKC) zeta is an important regulator of inflammation through activation of the nuclear factor-kappaB (NF-kappaB) pathway. Chromatin remodeling on pro-inflammatory genes plays a pivotal role in cigarette smoke (CS)- and lipopolysaccharide (LPS)-induced abnormal lung inflammation. However, the signaling mechanism whereby chromatin remodeling occurs in CS- and LPS-induced lung inflammation is not known. We hypothesized that PKCzeta is an important regulator of chromatin remodeling, and down-regulation of PKCzeta ameliorates lung inflammation by CS and LPS exposures. We determined the role and molecular mechanism of PKCzeta in abnormal lung inflammatory response to CS and LPS exposures in PKCzeta-deficient (PKCzeta(-/-)) and wild-type mice. Lung inflammatory response was decreased in PKCzeta(-/-) mice compared with WT mice exposed to CS and LPS. Moreover, inhibition of PKCzeta by a specific pharmacological PKCzeta inhibitor attenuated CS extract-, reactive aldehydes (present in CS)-, and LPS-mediated pro-inflammatory mediator release from macrophages. The mechanism underlying these findings is associated with decreased RelA/p65 phosphorylation (Ser(311)) and translocation of the RelA/p65 subunit of NF-kappaB into the nucleus. Furthermore, CS/reactive aldehydes and LPS exposures led to activation and translocation of PKCzeta into the nucleus where it forms a complex with CREB-binding protein (CBP) and acetylated RelA/p65 causing histone phosphorylation and acetylation on promoters of pro-inflammatory genes. Taken together, these data suggest that PKCzeta plays an important role in CS/aldehyde- and LPS-induced lung inflammation through acetylation of RelA/p65 and histone modifications via CBP. These data provide new insights into the molecular mechanisms underlying the pathogenesis of chronic inflammatory lung diseases.
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Affiliation(s)
- Hongwei Yao
- Department of Environmental Medicine, Lung Biology and Disease Program, University of Rochester Medical Center, Rochester, New York 14642, USA
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7
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Stross C, Keitel V, Winands E, Häussinger D, Kubitz R. Expression and localization of atypical PKC isoforms in liver parenchymal cells. Biol Chem 2009; 390:235-44. [PMID: 19090727 DOI: 10.1515/bc.2009.031] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Members of all three classes of the protein kinase C (PKC) family including atypical PKCzeta (PKCzeta) are involved in central functions of liver parenchymal cells. However, expression and localization of PKCiota (PKCiota), the highly homologous atypical PKC (aPKC) isoform, in hepatocytes is unknown to date. PKCzeta and PKCiota were cloned from human and rat liver and fused to fluorescent protein tags (YFP). The sequence of full-length rat PKCiota is not yet known and was cloned from cDNA of hepatocytes by the use of degenerated primers. PKCzeta-YFP and PKCiota-YFP (human and rat) were expressed in HeLa or HEK293 cells and used to test the specificity of seven aPKC antibodies. Two antibodies were PKCiota-specific and two were specific for PKCzeta in immunofluorescence and Western blot analysis. Subcellular localization was analyzed by immunofluorescence in isolated rat and human hepatocytes and liver sections. Low immunoreactivity for aPKCs was found at the sinusoidal membrane and in the cytosol. The highest density of PKCiota as well as PKCzeta was found at the canalicular membrane in co-localization with ABC-transporters, such as bile salt export pump or multidrug resistance-associated protein 2. This topology suggests a specific function of aPKCs at the canalicular membrane in addition to their known role in cell polarity of epithelial cells.
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Affiliation(s)
- Claudia Stross
- Clinic for Gastroenterology, Hepatology and Infectiology, Heinrich Heine University Düsseldorf, D-40225 Düsseldorf, Germany
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8
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Bierhals K, Sondersorg AC, Lin CT, Rosenbaum C, Waldmann H, Wehner F. The ε-Isoform of PKC Mediates the Hypertonic Activation of Cation Channels in Confluent Monolayers of Rat Hepatocytes. Cell Physiol Biochem 2008; 20:397-404. [PMID: 17762167 DOI: 10.1159/000107524] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/13/2007] [Indexed: 01/29/2023] Open
Abstract
We were interested whether PKC alpha, delta, epsilon or zeta is the isoform actually employed in the activation of hypertonicity-induced cation channels (HICCs) in primary cultures of rat hepatocytes. Quantitative SDS-page and Western-blot experiments revealed that PKC alpha, delta and epsilon were stimulated by Indolactam V (as a DAG substitute for activation of c and nPKCs) but that only PKC delta and epsilon did respond to hypertonic stress. Furthermore, chelation of intracellular Ca(++) by BAPTA-AM did not alter HICC activation in cable-analysis experiments whereas Indolactam V as well as V8 (an Indolactam derivative specific for PKC delta and epsilon) activated HICC currents under isotonic conditions. Finally, by use of Rottlerin (as an inhibitor exhibiting a slight preference for PKC delta over epsilon) PKC epsilon could be identified as the most likely isoform responsible for the activation of the HICC.
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Affiliation(s)
- Katrin Bierhals
- Department of Systemic Cell Biology, Max-Planck-Institute for Molecular Physiology, Dortmund, Germany
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9
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Crisanti P, Laplace O, Lecain E, Jonet L, Jeanny JC, Omri B. The role of PKCzeta in NMDA-induced retinal ganglion cell death: prevention by aspirin. Apoptosis 2007; 11:983-91. [PMID: 16547586 DOI: 10.1007/s10495-006-6750-2] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
Intravitreal NMDA injection has been shown to induce the excitotoxic loss of retinal cells. The retinal ganglion cell apoptosis induced by NMDA is thought to play an important role in retinal ischemia injury and NMDA-injected rat has been used as a model of neuronal loss in diseases such as glaucoma. In this experimental model, we studied the early effects of NMDA leading to the degeneration of retinal ganglion cells. PKCzeta regulates the NF-kappaB pathway in cellular responses to various stresses and we have shown that aspirin inhibits purified human PKCzeta. We therefore investigated the molecular mechanism by which retinal cells limit ocular injury following NMDA treatment. We found that the NMDA-induced apoptosis of ganglion cells was mediated, at least partly, by PKCzeta. This enzyme was activated early in the cellular response to NMDA. Prolonged activation was followed by PKCzeta cleavage, and nuclear translocation of the C-terminal region of this protein-a critical event for the survival of retinal cells. We also found that pretreatment with aspirin or the coinjection of NMDA with a specific PKCzeta inhibitor counteracted the effects of NMDA. These findings provide new insight into the role played by PKCzeta in neuronal loss in glaucoma.
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Affiliation(s)
- P Crisanti
- Unité 598 de l'INSERM Physiopathologie des maladies oculaires, Innovations thérapeutiques, France
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10
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Leseux L, Laurent G, Laurent C, Rigo M, Blanc A, Olive D, Bezombes C. PKC zeta mTOR pathway: a new target for rituximab therapy in follicular lymphoma. Blood 2007; 111:285-91. [PMID: 17855629 DOI: 10.1182/blood-2007-04-085092] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
Previous studies have documented that, in malignant B cells, rituximab elicits a complex and not yet totally understood signaling network contributing to its antitumor effect. In this context, we investigated the role of protein kinase C zeta (PKCzeta), an atypical PKC isoform, in the cellular response to rituximab. We found that follicular lymphoma cells displayed an increase in PKCzeta expression and activity levels, compared with nonmalignant B cells, and that this enzyme was a critical regulator of the classical MAPK module by stimulating Raf-1 kinase activity. PKCzeta appeared to be a significant contributor of abnormal mTOR regulation in follicular lymphoma cells through a MAPK-dependent mechanism. Rituximab was found to inhibit the PKCzeta/MAPK/mTOR module in these cells but not in other B-cell lymphomas. Importantly, the expression of a constitutively active form of PKCzeta resulted in an efficient protection of these cells toward rituximab. Altogether, our study describes a new regulatory component of mTOR pathway in follicular cell lymphoma and demonstrates that PKCzeta is a target for rituximab. Therefore, PKCzeta could represent an important parameter for rituximab efficacy and a promising target for future targeted therapy in follicular lymphoma.
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Affiliation(s)
- Ludivine Leseux
- INSERM, Unite 563, Centre de Physiopathologie de Toulouse Purpan, Université Toulouse III Paul-Sabatier, Toulouse, France
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11
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Lecain E, Omri B, Behar-Cohen F, Tran Ba Huy P, Crisanti P. The role of PKCzeta in amikacin-induced apoptosis in the cochlea: prevention by aspirin. Apoptosis 2007; 12:333-42. [PMID: 17191118 DOI: 10.1007/s10495-006-0580-0] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
Aminoglycoside antibiotics are ototoxic, inducing irreversible sensorineural hearing loss mediated by oxidative and excitotoxic stresses. The NF-kappaB pathway is involved in the response to aminoglycoside damage in the cochlea. However, the molecular mechanisms of this ototoxicity remain unclear. We investigated the expression of PKCzeta, a key regulator of NF-kappaB activation, in response to aminoglycoside treatment. Amikacin induced PKCzeta cleavage and nuclear translocation. These events were concomitant with chromatin condensation and paralleled the decrease in NF-kappaB (p65) levels in the nucleus. Amikacin also induced the nuclear translocation of apoptotic inducing factor (AIF). Prior treatment with aspirin prevented PKCzeta cleavage and nuclear translocation. Thus, aspirin counteracts the early effects of amikacin, thereby protecting hair cells and spiral ganglion neurons. These results demonstrate that PKCzeta acts as sentinel connecting specific survival pathways to mediate cellular responses to amikacin ototoxicity.
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Affiliation(s)
- Eric Lecain
- Hôpital Lariboisière, Service ORL, 2 rue Ambroise Paré, 75010, Paris, France
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12
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Gayral S, Déléris P, Laulagnier K, Laffargue M, Salles JP, Perret B, Record M, Breton-Douillon M. Selective activation of nuclear phospholipase D-1 by g protein-coupled receptor agonists in vascular smooth muscle cells. Circ Res 2006; 99:132-9. [PMID: 16778131 DOI: 10.1161/01.res.0000232323.86227.8b] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Recent studies highlight the existence of an autonomous nuclear lipid metabolism related to cellular proliferation. However, the importance of nuclear phosphatidylcholine (PC) metabolism is poorly understood. Therefore, we were interested in nuclear PCs as a source of second messengers and, particularly, nuclear phospholipase D (PLD) identification in membrane-free nuclei isolated from pig aorta vascular smooth muscle cells (VSMCs). Using immunoblot experiment, in vitro PLD assay with fluorescent substrate and confocal microscopy analysis, we demonstrated that only PLD1 is expressed in VSMC nucleus, whereas PLD1 and PLD2 are present in VSMC. Inhibition of RhoA and protein kinase Czeta (PKCzeta) by C3-exoenzyme and PKCzeta pseudosubstrate inhibitor, respectively, conducted a decrease of phosphatidylethanol production. On the other hand, treatment of intact VSMCs, but not nuclei, with phosphoinositide 3-kinase (PI3K) inhibitors prevented partially nuclear PLD1 activity, indicating for the first time that PI3K may have a role in nuclear PLD regulation. In addition, lysophosphatidic acid (LPA) or angiotensin II treatment of VSMCs resulted in an increase of intranuclear PLD activity, whereas platelet-derived growth factor and epidermal growth factor have no significant effect. Moreover, pertussis toxin induced a decrease of LPA-stimulated nuclear PLD1 activity, suggesting that heterotrimeric G(i)/G(0) protein involvement in intranuclear PLD1 regulation. We also show that LPA-induced nuclear PLD1 activation implied PI3K/PKCzeta pathway activation and PKCzeta nuclear translocation as well as nuclear RhoA activation. Thus, the characterization of an endogenous PLD1 that could regulate PC metabolism inside VSMC nucleus provides a new role for this enzyme in control of vascular fibroproliferative disorders.
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Affiliation(s)
- Stéphanie Gayral
- Département Lipoprotéines and Médiateurs Lipidiques, CPTP, INSERM Unité 563, Bâtiment C, CHU Purpan, BP 3028, 31024 Toulouse Cedex 3, France
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13
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Déléris P, Gayral S, Breton-Douillon M. Nuclear Ptdlns(3,4,5)P3 signaling: an ongoing story. J Cell Biochem 2006; 98:469-85. [PMID: 16645993 DOI: 10.1002/jcb.20695] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Phosphatidylinositol 3,4,5-trisphosphate (Ptdlns(3,4,5)P(3)) is linked to a variety of cellular functions, such as growth, cell survival, and differentiation. Ptdlns(3,4,5)P(3) is primarily synthesized by class I phosphoinositide 3-kinases and its hydrolysis by two 3-phosphoinositide 3-phosphatases, PTEN and SHIP proteins, leads to the production of two other second messengers, Ptdlns(4,5)P(2) and Ptdlns(3,4)P(2), respectively. Evidence accumulated over the last years strongly suggest that Ptdlns(3,4,5)P(3) is an important component of signaling pathway operating within the nucleus. Moreover, recent advances indicated that nuclear translocation of cell surface receptors could activate nuclear phosphoinositide 3-kinase suggesting a new mode of signal transduction. The aim of this review is intended to summarize the state of our knowledge on nuclear Ptdlns(3,4,5)P(3) and its metabolizing enzymes, and to highlight the emerging roles for intranuclear Ptdlns(3,4,5)P(3).
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Affiliation(s)
- Paul Déléris
- Laboratoire de Signalisation et Croissance Cellulaire, Institut de Recherche en Immunovirologie et Cancérologie, Université de Montréal, Montréal, QC H3T 1J4 Canada
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14
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Cocco L, Faenza I, Fiume R, Maria Billi A, Gilmour RS, Manzoli FA. Phosphoinositide-specific phospholipase C (PI-PLC) β1 and nuclear lipid-dependent signaling. Biochim Biophys Acta Mol Cell Biol Lipids 2006; 1761:509-21. [PMID: 16624616 DOI: 10.1016/j.bbalip.2006.03.001] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2005] [Revised: 03/02/2006] [Accepted: 03/03/2006] [Indexed: 10/24/2022]
Abstract
Over the last years, evidence has suggested that phosphoinositides, which are involved in the regulation of a large variety of cellular processes both in the cytoplasm and in the plasma membrane, are present also within the nucleus. A number of advances has resulted in the discovery that phosphoinositide-specific phospholipase C signalling in the nucleus is involved in cell growth and differentiation. Remarkably, the nuclear inositide metabolism is regulated independently from that present elsewhere in the cell. Even though nuclear inositol lipids hydrolysis generates second messengers such as diacylglycerol and inositol 1,4,5-trisphosphate, it is becoming increasingly clear that in the nucleus polyphosphoinositides may act by themselves to influence pre-mRNA splicing and chromatin structure. Among phosphoinositide-specific phospholipase C, the beta(1) isoform appears to be one of the key players of the nuclear lipid signaling. This review aims at highlighting the most significant and up-dated findings about phosphoinositide-specific phospholipase C beta(1) in the nucleus.
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Affiliation(s)
- Lucio Cocco
- Cellular Signalling Laboratory, Department of Human Anatomical Sciences, University of Bologna, Via Irnerio 48, 40126 Bologna, Italy.
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15
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Martelli AM, Evangelisti C, Nyakern M, Manzoli FA. Nuclear protein kinase C. Biochim Biophys Acta Mol Cell Biol Lipids 2006; 1761:542-51. [PMID: 16574477 DOI: 10.1016/j.bbalip.2006.02.009] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2005] [Accepted: 02/16/2006] [Indexed: 11/20/2022]
Abstract
Protein kinase C (PKC) isozymes constitute a family of ubiquitous phosphotransferases which act as key transducers in many agonist-induced signaling cascades. To date, at least 11 different PKC isotypes have been identified and are believed to play distinct regulatory roles. PKC isoforms are physiologically activated by a number of lipid cofactors. PKC is thought to reside in the cytoplasm in an inactive conformation and to translocate to the plasma membrane or cytoplasmic organelles upon cell activation by different stimuli. However, a sizable body of evidence collected over the last 20 years has shown PKC to be capable of translocating to the nucleus. Furthermore, PKC isoforms are resident within the nucleus. Studies from independent laboratories have to led to the identification of quite a few nuclear proteins which are PKC substrates and to the characterization of nuclear PKC-binding proteins which may be critical for finely tuning PKC function in this cell microenvironment. Several lines of evidence suggest that nuclear PKC isozymes are involved in the regulation of biological processes as important as cell proliferation and differentiation, gene expression, neoplastic transformation, and apoptosis. In this review, we shall highlight the most intriguing and updated findings about the functions of nuclear PKC isozymes.
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Affiliation(s)
- Alberto M Martelli
- Dipartimento di Scienze Anatomiche Umane e Fisiopatologia dell'Apparato Locomotore, Sezione di Anatomia Umana, Cell Signalling Laboratory, Università di Bologna, 40126 Bologna, Italy.
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16
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Crisanti P, Leon A, Lim DM, Omri B. Aspirin prevention of NMDA-induced neuronal death by direct protein kinase Cζ inhibition. J Neurochem 2005; 93:1587-93. [PMID: 15935075 DOI: 10.1111/j.1471-4159.2005.03157.x] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
Abstract Aspirin has been shown to protect against glutamate neurotoxicity via the nuclear factor kappaB pathway. Some studies have implicated the atypical protein kinase C (PKC) zeta (zeta) isoform in cell protection, but the mechanism involved remains unclear. We show here that aspirin exerts at least some of its effects through PKCzeta, decreasing the NMDA-induced activation, cleavage and nuclear translocation of this molecule. Aspirin (acetylsalicylic acid) directly inhibited the protein kinase activity of PKCzeta, whereas salicylic acid did not. This direct effect of aspirin on purified human PKCzeta is consistent with PKCzeta inhibition preventing the NMDA-induced death of cortical neurones. Caspase-3 inhibition blocked the cleavage and nuclear translocation of PKCzeta, whereas caspase-1-inhibition did not. Thus, PKCzeta (protein kinase Mzeta) regulates nuclear events essential for the initiation of the apoptotic pathway. Aspirin protects cells against NMDA-induced apoptosis by means of a novel mechanism targeting PKCzeta, a key molecule in inflammatory responses and neurodegeneration.
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Affiliation(s)
- P Crisanti
- Unité 598 de l'Institut National de la Sante Et de la Recherche Medicale: Physiopathologie des maladies oculaires: Innovations thérapeutiques, Paris, France
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Miguel BG, Rodriguez ME, Aller P, Martinez AM, Mata F. Regulation of cadmium-induced apoptosis by PKCδ in U937 human promonocytic cells. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2005; 1743:215-22. [PMID: 15843035 DOI: 10.1016/j.bbamcr.2004.10.011] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/23/2004] [Revised: 07/29/2004] [Accepted: 10/15/2004] [Indexed: 11/20/2022]
Abstract
Pulse treatment with cadmium chloride followed by recovery caused apoptosis in U937 human promonocytic cells. In addition, the treatment-induced PKCdelta translocation from cytosol to membrane fraction, which was already detected at 30 min of treatment; and also caused PKCdelta cleavage to give a 41-kDa fragment, which was detected at 3-6 h of recovery, concomitantly with the execution of apoptosis. All these effects were reduced by the PKCdelta-specific inhibitor rottlerin. By contrast, rottlerin did not prevent the cadmium-provoked stimulation of the stress response (as measured by HSP70 expression), nor inhibited the generation of apoptosis by heat-shock, which failed to cause PKCdelta translocation. Cadmium chloride rapidly induced p38(MAPK) activation, which was not affected by rottlerin. By contrast, the p38(MAPK) inhibitor SB203580 reduced PKCdelta translocation and cleavage, indicating that p38(MAPK) activation precedes and regulates PKCdelta activation. It is concluded that PKCdelta mediates apoptosis induction by cadmium ions via early membrane translocation, and also possibly through late kinase proteolytic cleavage and phosphorylation on tyrosine residues.
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Affiliation(s)
- Begoña G Miguel
- Dept. Bioquímica y Biología Molecular I, Facultad de Biología, Universidad Complutense de Madrid, 28040 Madrid, Spain
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18
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Symolon H, Schmelz EM, Dillehay DL, Merrill AH. Dietary soy sphingolipids suppress tumorigenesis and gene expression in 1,2-dimethylhydrazine-treated CF1 mice and ApcMin/+ mice. J Nutr 2004; 134:1157-61. [PMID: 15113963 DOI: 10.1093/jn/134.5.1157] [Citation(s) in RCA: 92] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
Dietary supplementation with milk sphingolipids inhibits colon tumorigenesis in CF1 mice treated with a colon carcinogen [1,2-dimethylhydrazine (DMH)] and in multiple intestinal neoplasia (Min) mice, which develop intestinal tumors spontaneously. Plant sphingolipids differ structurally from those of mammals [soy glucosylceramide (GlcCer) consists predominantly of a 4,8-sphingadiene backbone and alpha-hydroxy-palmitic acid], which might affect their bioactivity. Soy GlcCer was added to the AIN-76A diet (which contains <0.005% sphingolipid) to investigate whether it would also suppress tumorigenesis in these mouse models. Soy GlcCer reduced colonic cell proliferation in the upper half of the crypts in mice treated with DMH by 50 and 56% (P < 0.05) at 0.025 and 0.1% of the diet (wt/wt), respectively, and reduced the number of aberrant colonic crypt foci (an early marker of colon carcinogenesis) by 38 and 52% (P < 0.05). Min mice fed diets containing 0.025 and 0.1% (wt/wt) soy GlcCer developed 22 and 37% fewer adenomas (P < 0.05), respectively. The effects of dietary sphingolipids on gene expression in the intestinal mucosal cells of Min mice were analyzed using Affymetrix GeneChip microarrays. Soy GlcCer affected the expression of 96 genes by > or = 2-fold in a dose-dependent manner, increasing 32 and decreasing 64. Decreases in the mRNA expression of two transcription factors associated with cancer, hypoxia-induced factor 1 alpha (HIF1 alpha) and transcription factor 4 (TCF4), were confirmed by quantitative RT-PCR. In conclusion, soy GlcCer suppressed colon tumorigenesis in two mouse models; hence, plant sphingolipids warrant further investigation as inhibitors of colon cancer. Because soy contains relatively high amounts of GlcCer, sphingolipids may partially account for the anticancer benefits attributed to soy-based foods.
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Affiliation(s)
- Holly Symolon
- Program in Nutrition and Health Science, Emory University, Atlanta, GA 30322, USA
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19
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McConkey M, Gillin H, Webster CRL, Anwer MS. Cross-talk between protein kinases Czeta and B in cyclic AMP-mediated sodium taurocholate co-transporting polypeptide translocation in hepatocytes. J Biol Chem 2004; 279:20882-8. [PMID: 15007074 DOI: 10.1074/jbc.m309988200] [Citation(s) in RCA: 57] [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
Cyclic AMP stimulates taurocholate (TC) uptake and sodium taurocholate co-transporting polypeptide (Ntcp) translocation in hepatocytes via the phosphoinositide-3 kinase (PI3K) signaling pathway. The aim of the present study was to determine whether protein kinase (PK) Czeta, one of the downstream mediators of the PI3K signaling pathway, is involved in cAMP-mediated stimulation of TC uptake. Studies were conducted in isolated rat hepatocytes and in HuH-7 cells stably transfected with rat liver Ntcp (HuH-Ntcp cells). Studies in hepatocytes showed that cAMP activates PKCzeta in a PI3K-dependent manner without inducing translocation of PKCzeta to the plasma membrane. Inhibition of cAMP-induced PKCzeta activity by myristoylated PKC (zeta/lambda) pseudosubstrate, a specific inhibitor of PKCzeta, and Gö 6850, a PKC inhibitor, resulted in inhibition of cAMP-induced increases in TC uptake and Ntcp translocation. Studies in HuH-Ntcp cells showed that inhibition of cAMP-induced PKCzeta activation by dominant-negative (DN) PKCzeta resulted in inhibition of cAMP-induced increases in TC uptake and Ntcp translocation. DN PKCzeta also inhibited wild-type PKCzeta-induced increases in PKCzeta activity, TC uptake, and Ntcp translocation. Myristoylated PKC (zeta/lambda) pseudosubstrate and DN PKCzeta also inhibited cAMP-induced activation of PKB in hepatocytes and HuH-Ntcp cells, respectively. Neither DN PKB nor constitutively active PKB affected cAMP-induced activation of PKCzeta, and wild-type PKCzeta did not activate PKB. Taken together, these results suggest that cAMP-induced activation of PKB is dependent on cAMP-induced stimulation of PKCzeta. It is proposed that cAMP-induced Ntcp translocation involves the activation of the PI3K/PKCzeta signaling pathway followed by the activation of the PI3K/PKB signaling pathway.
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Affiliation(s)
- Marie McConkey
- Department of Biomedical Sciences, Tufts University School of Veterinary Medicine, 200 Westboro Road, North Grafton, MA 01536, USA
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20
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Perrini S, Henriksson J, Zierath JR, Widegren U. Exercise-induced protein kinase C isoform-specific activation in human skeletal muscle. Diabetes 2004; 53:21-4. [PMID: 14693693 DOI: 10.2337/diabetes.53.1.21] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
We determined whether protein kinase C (PKC) isoforms are redistributed and phosphorylated in response to acute exercise in skeletal muscle. Muscle biopsies were obtained from six healthy subjects (four women, two men; age 25 +/- 1 years) before, during, and after 60 min of one-leg cycle ergometry at approximately 70% VO(2peak). Exercise for 30 and 60 min was associated with a three- and fourfold increase in PKC-zeta/lambda abundance and a four- and threefold increase in phosphorylation, respectively, in total membranes (P < 0.05) and a decrease in PKC-zeta/lambda phosphorylation in cytosolic fractions. During exercise recovery, PKC-zeta/lambda abundance and phosphorylation remained elevated. PKC-zeta/lambda abundance and phosphorylation were increased in nonexercised muscle upon cessation of exercise, indicating a systemic response may contribute to changes in PKC abundance and phosphorylation. Exercise did not change PKC-delta or -epsilon abundance or phosphorylation in either the cytosolic or total membrane fraction. In conclusion, exercise is associated with an isoform-specific effect on PKC. PKC-zeta/lambda are candidate PKC isoforms that may play a role in the regulation of exercise-related changes in metabolic and gene-regulatory responses.
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Affiliation(s)
- Sebastio Perrini
- Department of Surgical Sciences, Section for Integrative Physiology, Karolinska Institutet, Stockholm, Sweden
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21
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Abstract
Strong evidence has been accumulating over the last 15 years suggesting that phosphoinositides, which are involved in the regulation of a large variety of cellular processes in the cytoplasm and in the plasma membrane, are present within the nucleus. Several advances have resulted in the discovery that nuclear phosphoinositides are involved in cell growth and differentiation. Remarkably, the nuclear inositide metabolism is regulated independently from that present elsewhere in the cell. Although nuclear inositol lipids generate second messengers such as diacylglycerol and inositol 1,4,5-trisphosphate, it is becoming increasingly clear that in the nucleus polyphosphoinositides may act by themselves to influence pre-mRNA splicing and chromatin structure. This review aims at highlighting the most significant and updated findings about inositol lipid metabolism in the nucleus.
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Affiliation(s)
- Alberto M Martelli
- Cellular Signalling Laboratory, Department of Human Anatomical Sciences, University of Bologna, via Irnerio 48, 40126, Bologna, Italy
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22
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Abstract
Phosphoinositides are minor components of biological membranes, which have emerged as essential regulators of a variety of cellular processes, both on the plasma membrane and on several intracellular organelles. The versatility of these lipids stems from their ability to function either as substrates for the generation of second messengers, as membrane-anchoring sites for cytosolic proteins or as regulators of the actin cytoskeleton. Despite a vast literature demonstrating the presence of phosphoinositides in the nucleus, only recently has the function(s) of the nuclear pool of these lipids and their soluble analogues, inositol polyphosphates, started to emerge. These compounds have been shown to serve as essential co-factors for several nuclear processes, including DNA repair, transcription regulation and RNA dynamics. In this light, phosphoinositides and inositol polyphosphates might represent high turnover activity switches for nuclear complexes responsible for these processes. The regulation of these large machineries would be linked to the phosphorylation state of the inositol ring and limited temporally and spatially based on the synthesis and degradation of these molecules.
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Affiliation(s)
- G Hammond
- Molecular NeuroPathoBiology Laboratory, Lincoln's Inn Fields Laboratories, Cancer Research UK London Research Institute, 44 Lincoln's Inn Fields, London WC2A 3PX, UK
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Déléris P, Bacqueville D, Gayral S, Carrez L, Salles JP, Perret B, Breton-Douillon M. SHIP-2 and PTEN are expressed and active in vascular smooth muscle cell nuclei, but only SHIP-2 is associated with nuclear speckles. J Biol Chem 2003; 278:38884-91. [PMID: 12847108 DOI: 10.1074/jbc.m300816200] [Citation(s) in RCA: 69] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Recently, the control of phosphatidylinositol 3,4,5-trisphosphate (PtdIns(3,4,5)P3)-dependant signaling by phosphatases has emerged, but there is a shortage of information on intranuclear PtdIns(3,4,5)P3 phosphatases. Therefore, we investigated the dephosphorylation of [32P]PtdIns(3,4,5)P3 specifically labeled on the D-3 position of the inositol ring in membrane-free nuclei isolated from pig aorta vascular smooth muscle cells (VSMCs). In vitro PtdIns(3,4,5)P3 phosphatase assays revealed the production of both [32P]PtdIns(3,4)P2 and inorganic phosphate, demonstrating the presence of PtdIns(3,4,5)P3 5- and 3-phosphatase activities inside the VSMC nucleus, respectively. Both activities presented the same potency in cellular lysates, whereas the nuclear PtdIns(3,4,5)P3 5-phosphatase activity appeared to be the most efficient. Immunoblot experiments showed for the first time the expression of the 5-phosphatase SHIP-2 (src homology 2 domain-containing inositol phosphatase) as well as the 3-phosphatase PTEN (phosphatase and tensin homolog deleted on chromosome 10) in VSMC nuclei. In addition, immunoprecipitations from nuclear fractions indicated a [32P]PtdIns(3,4,5)P3 dephosphorylation by both SHIP-2 and PTEN. Moreover, confocal microscopy analyses demonstrated that SHIP-2 but not PTEN colocalized with a speckle-specific component, the SC35 splicing factor. These results suggest that SHIP-2 may be the primary enzyme for metabolizing PtdIns(3,4,5)P3 into PtdIns(3,4)P2 within the nucleus, thus producing another second messenger, whereas PTEN could down-regulate nuclear phosphoinositide 3-kinase signaling. Finally, intranuclear PtdIns(3,4,5)P3 phosphatases might be involved in the control of VSMC proliferation and the pathogenesis of vascular proliferative disorders.
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Affiliation(s)
- Paul Déléris
- Centre de Physiopathologie Toulouse Purpan, INSERM Unité 563, Département LML, Hôpital Purpan, 31059 Toulouse, France
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Wu D, Marko M, Claycombe K, Paulson KE, Meydani SN. Ceramide-induced and age-associated increase in macrophage COX-2 expression is mediated through up-regulation of NF-kappa B activity. J Biol Chem 2003; 278:10983-92. [PMID: 12529332 DOI: 10.1074/jbc.m207470200] [Citation(s) in RCA: 88] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
We have shown that the age-associated increase in lipopolysaccharide (LPS)-stimulated macrophages (M phi) prostaglandin E(2) (PGE(2)) production is because of ceramide-induced up-regulation of cyclooxygenase (COX)-2 transcription that leads to increased COX-2 expression and enzyme activity. To determine the mechanism of the age-related and ceramide-dependent increase in COX-2 transcription, we investigated the role of various transcription factors involved in COX-2 gene expression. The results showed that LPS-initiated activations of both consensus and COX-2-specific NF-kappa B, but not AP-1 and CREB, were significantly higher in M phi from old mice than those from young mice. We further showed that the higher NF-kappa B activation in old M phi was because of greater I kappa B degradation in the cytoplasm and p65 translocation to the nucleus. An I kappa B phosphorylation inhibitor, Bay 11-7082, inhibited NF-kappa B activation, as well as PGE(2) production, COX activity, COX-2 protein, and mRNA expression in both young and old M phi. Similar results were obtained by blocking NF-kappa B binding activity using a NF-kappa B decoy. Furthermore, NF-kappa B inhibition resulted in significantly greater reduction in PGE(2) production and COX activity in old compared with young M phi. Addition of ceramide to the young M phi, in the presence or absence of LPS, increased NF-kappa B activation in parallel with PGE(2) production. Bay 11-7082 or NF-kappa B decoy prevented this ceramide-induced increase in NF-kappa B binding activity and PGE(2) production. These findings strongly suggest that the age-associated and ceramide-induced increase in COX-2 transcription is mediated through higher NF-kappa B activation, which is, in turn, because of a greater I kappa B degradation in old M phi.
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Affiliation(s)
- Dayong Wu
- Nutritional Immunology Laboratory, Jean Mayer USDA Human Nutrition Research Center on Aging, Tufts University, Boston, Massachusetts 02111,USA
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25
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Martelli AM, Tabellini G, Borgatti P, Bortul R, Capitani S, Neri LM. Nuclear lipids: new functions for old molecules? J Cell Biochem 2003; 88:455-61. [PMID: 12532322 DOI: 10.1002/jcb.10379] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
It is becoming increasingly evident that stimulation of nuclear lipid metabolism plays a central role in many signal transduction pathways that ultimately result in various cell responses including proliferation and differentiation. Nuclear lipid metabolism seems to be at least as complex as that existing at the plasma membrane. However, a distinctive feature of nuclear lipid biochemical pathways is their operational independence from their cell periphery counterparts. Although initially it was thought that nuclear lipids would serve as a source for second messengers, recent evidence points to the likelihood that lipids present in the nucleus also fulfil other roles. The aim of this review is to highlight the most intriguing advances made in the field over the last year, such as the production of new probes for the in situ mapping of nuclear phosphoinositides, the identification of two sources for nuclear diacylglycerol production, the emerging details about the peculiar regulation of nuclear phosphoinositide synthesizing enzymes, and the distinct possibility that nuclear lipids are involved in processes such as chromatin organization and pre-mRNA splicing.
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Affiliation(s)
- Alberto M Martelli
- Dipartimento di Scienze Anatomiche Umane e Fisiopatologia dell'Apparato Locomotore, Sezione di Anatomia, Cell Signaling Laboratory, Università di Bologna, Via Irnerio 48, Italy.
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26
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van Blitterswijk WJ, van der Luit AH, Veldman RJ, Verheij M, Borst J. Ceramide: second messenger or modulator of membrane structure and dynamics? Biochem J 2003; 369:199-211. [PMID: 12408751 PMCID: PMC1223095 DOI: 10.1042/bj20021528] [Citation(s) in RCA: 335] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2002] [Revised: 10/30/2002] [Accepted: 10/31/2002] [Indexed: 12/18/2022]
Abstract
The physiological role of ceramide formation in response to cell stimulation remains controversial. Here, we emphasize that ceramide is not a priori an apoptotic signalling molecule. Recent work points out that the conversion of sphingomyelin into ceramide can play a membrane structural (physical) role, with consequences for membrane microdomain function, membrane vesiculation, fusion/fission and vesicular trafficking. These processes contribute to cellular signalling. At the Golgi, ceramide takes part in a metabolic flux towards sphingomyelin, diacylglycerol and glycosphingolipids, which drives lipid raft formation and vesicular transport towards the plasma membrane. At the cell surface, receptor clustering in lipid rafts and the formation of endosomes can be facilitated by transient ceramide formation. Also, signalling towards mitochondria may involve glycosphingolipid-containing vesicles. Ceramide may affect the permeability of the mitochondrial outer membrane and the release of cytochrome c. In the effector phase of apoptosis, the breakdown of plasma membrane sphingomyelin to ceramide is a consequence of lipid scrambling, and may regulate apoptotic body formation. Thus ceramide formation serves many different functions at distinct locations in the cell. Given the limited capacity for spontaneous intracellular diffusion or membrane flip-flop of natural ceramide species, the topology and membrane sidedness of ceramide generation are crucial determinants of its impact on cell biology.
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Affiliation(s)
- Wim J van Blitterswijk
- Division of Cellular Biochemistry, The Netherlands Cancer Institute, Plesmanlaan 121, 1066 CX Amsterdam, The Netherlands.
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Neri LM, Borgatti P, Capitani S, Martelli AM. The nuclear phosphoinositide 3-kinase/AKT pathway: a new second messenger system. BIOCHIMICA ET BIOPHYSICA ACTA 2002; 1584:73-80. [PMID: 12385889 DOI: 10.1016/s1388-1981(02)00300-1] [Citation(s) in RCA: 133] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Lipid second messengers, particularly those derived from the polyphosphoinositide cycle, play a pivotal role in several cell signaling networks. Phosphoinositide 3-kinases (PI3Ks) generate specific inositol lipids that have been implicated in a plethora of cell functions. One of the best-characterized targets of PI3K lipid products is the serine/threonine protein kinase Akt. Recent findings have implicated Akt in cancer progression because it stimulates cell proliferation and suppresses apoptosis. Evidence accumulated over the past 15 years has highlighted the presence of an autonomous nuclear inositol lipid metabolism, and suggests that lipid molecules are important components of signaling pathways operating within the nucleus. PI3Ks, their lipid products, and Akt have also been identified at the nuclear level. In this review, we shall summarize the most updated findings about these molecules in relationship with the nuclear compartment and provide an overview of the possible mechanisms by which they regulate important cell functions.
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Affiliation(s)
- Luca M Neri
- Dipartimento di Morfologia ed Embriologia, Sezione di Anatomia Umana, Università di Ferrara, via Fossato di Mortara 66, 44100 Ferrara, Italy.
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