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Ongusaha PP, Kim HG, Boswell SA, Ridley AJ, Der CJ, Dotto GP, Kim YB, Aaronson SA, Lee SW. Retraction Notice to: RhoE Is a Pro-Survival p53 Target Gene that Inhibits ROCK I-Mediated Apoptosis in Response to Genotoxic Stress. Curr Biol 2019; 29:2107. [DOI: 10.1016/j.cub.2019.05.065] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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Ongusaha PP, Kim HG, Boswell SA, Ridley AJ, Der CJ, Dotto GP, Kim YB, Aaronson SA, Lee SW. RhoE Is a Pro-Survival p53 Target Gene that Inhibits ROCK I-Mediated Apoptosis in Response to Genotoxic Stress. Curr Biol 2016; 26:2221-2222. [PMID: 27554646 DOI: 10.1016/j.cub.2016.07.072] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Ouchi M, Fujiuchi N, Sasai K, Katayama H, Minamishima YA, Ongusaha PP, Deng C, Sen S, Lee SW, Ouchi T. Retraction. BRCA1 phosphorylation by Aurora-A in the regulation of G2 to M transition. J Biol Chem 2016; 290:22311. [PMID: 26341884 DOI: 10.1074/jbc.a115.311780] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
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Montalvo J, Spencer C, Hackathorn A, Masterjohn K, Perkins A, Doty C, Arumugam A, Ongusaha PP, Lakshmanaswamy R, Liao JK, Mitchell DC, Bryan BA. ROCK1 & 2 perform overlapping and unique roles in angiogenesis and angiosarcoma tumor progression. Curr Mol Med 2013; 13:205-19. [PMID: 22934846 PMCID: PMC3580831 DOI: 10.2174/1566524011307010205] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2012] [Revised: 07/21/2012] [Accepted: 07/30/2012] [Indexed: 12/31/2022]
Abstract
The serine/threonine protein kinase paralogs ROCK1 & 2 have been implicated as essential modulators of angiogenesis; however their paralog-specific roles in endothelial function are unknown. shRNA knockdown of ROCK1 or 2 in endothelial cells resulted in a significant disruption of in vitro capillary network formation, cell polarization, and cell migration compared to cells harboring non-targeting control shRNA plasmids. Knockdowns led to alterations in cytoskeletal dynamics due to ROCK1 & 2-mediated reductions in actin isoform expression, and ROCK2-specific reduction in myosin phosphatase and cofilin phosphorylation. Knockdowns enhanced cell survival and led to ROCK1 & 2-mediated reduction in caspase 6 and 9 cleavage, and a ROCK2-specific reduction in caspase 3 cleavage. Microarray analysis of ROCK knockdown lines revealed overlapping and unique control of global transcription by the paralogs, and a reduction in the transcriptional regulation of just under 50% of VEGF responsive genes. Finally, paralog knockdown in xenograft angiosarcoma tumors resulted in a significant reduction in tumor formation. Our data reveals that ROCK1 & 2 exhibit overlapping and unique roles in normal and dysfunctional endothelial cells, that alterations in cytoskeletal dynamics are capable of overriding mitogen activated transcription, and that therapeutic targeting of ROCK signaling may have profound impacts for targeting angiogenesis.
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Affiliation(s)
- J Montalvo
- Ghosh Science and Technology Center, Department of Biology, Worcester State University, Worcester, Massachusetts, USA
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Zhou Q, Mei Y, Shoji T, Han X, Kaminski K, Oh GT, Ongusaha PP, Zhang K, Schmitt H, Moser M, Bode C, Liao JK. Rho-associated coiled-coil-containing kinase 2 deficiency in bone marrow-derived cells leads to increased cholesterol efflux and decreased atherosclerosis. Circulation 2012; 126:2236-47. [PMID: 23011471 DOI: 10.1161/circulationaha.111.086041] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
BACKGROUND Macrophages play a central role in the development of atherosclerosis. However, the signaling pathways that regulate their function are not well understood. The Rho-associated coiled-coil-containing kinases (ROCK1 and ROCK2) are serine-threonine protein kinases that are involved in the regulation of the actin cytoskeleton. Recent studies suggest that ROCK1 in macrophages and bone marrow-derived cells mediates atherogenesis. However, a similar role for ROCK2 in the pathogenesis of atherosclerosis has not been determined. METHODS AND RESULTS The bone marrows from wild-type, ROCK2(+/-), and ROCK2(-/-) mice were transplanted into irradiated recipient low-density lipoprotein receptor(-/-) mice, and atherosclerosis was induced with a 16-week high-cholesterol diet. Compared with wild-type bone marrow-transplanted mice, ROCK2(+/-) bone marrow-transplanted and ROCK2(-/-) bone marrow-transplanted mice showed substantially less lipid accumulation in the aorta (8.46±1.42% and 9.80±2.34% versus 15.64±1.89%; P<0.01 for both) and decreased atherosclerotic lesions in the subaortic sinus (158.1±44.4 and 330.1±109.5×10(3)μm(2) versus 520.2±125.7×10(3)μm(2); P<0.01 for both). These findings correlated with decreased foam cell formation (2.27±0.57 versus 4.10±0.3; P<0.01) and increased cholesterol efflux (17.65±0.6 versus 9.75±0.8; P<0.05) in ROCK2-deficient mice that are mediated, in part, through the peroxisome proliferator-activated receptor-γ/liver X receptor/ATP-binding cassette transporter A1 pathway in macrophages. CONCLUSIONS ROCK2 contributes to atherosclerosis, in part, by inhibiting peroxisome proliferator-activated receptor-γ-mediated reverse cholesterol transport in macrophages, which contributes to foam cell formation. These findings suggest that inhibition of ROCK2 in macrophages may have therapeutic benefits in preventing the development of atherosclerosis.
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Affiliation(s)
- Qian Zhou
- Vascular Medicine Research Unit, Brigham and Women’s Hospital and Harvard Medical School, Boston, MA, USA
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Qi HH, Sarkissian M, Hu GQ, Wang Z, Bhattacharjee A, Gordon DB, Gonzales M, Lan F, Ongusaha PP, Huarte M, Yaghi NK, Lim H, Garcia BA, Brizuela L, Zhao K, Roberts TM, Shi Y. Histone H4K20/H3K9 demethylase PHF8 regulates zebrafish brain and craniofacial development. Nature 2010; 466:503-7. [PMID: 20622853 PMCID: PMC3072215 DOI: 10.1038/nature09261] [Citation(s) in RCA: 224] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2009] [Accepted: 06/10/2010] [Indexed: 12/18/2022]
Abstract
X-linked mental retardation (XLMR) is a complex human disease that causes intellectual disability. Causal mutations have been found in approximately 90 X-linked genes; however, molecular and biological functions of many of these genetically defined XLMR genes remain unknown. PHF8 (PHD (plant homeo domain) finger protein 8) is a JmjC domain-containing protein and its mutations have been found in patients with XLMR and craniofacial deformities. Here we provide multiple lines of evidence establishing PHF8 as the first mono-methyl histone H4 lysine 20 (H4K20me1) demethylase, with additional activities towards histone H3K9me1 and me2. PHF8 is located around the transcription start sites (TSS) of approximately 7,000 RefSeq genes and in gene bodies and intergenic regions (non-TSS). PHF8 depletion resulted in upregulation of H4K20me1 and H3K9me1 at the TSS and H3K9me2 in the non-TSS sites, respectively, demonstrating differential substrate specificities at different target locations. PHF8 positively regulates gene expression, which is dependent on its H3K4me3-binding PHD and catalytic domains. Importantly, patient mutations significantly compromised PHF8 catalytic function. PHF8 regulates cell survival in the zebrafish brain and jaw development, thus providing a potentially relevant biological context for understanding the clinical symptoms associated with PHF8 patients. Lastly, genetic and molecular evidence supports a model whereby PHF8 regulates zebrafish neuronal cell survival and jaw development in part by directly regulating the expression of the homeodomain transcription factor MSX1/MSXB, which functions downstream of multiple signalling and developmental pathways. Our findings indicate that an imbalance of histone methylation dynamics has a critical role in XLMR.
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Affiliation(s)
- Hank H Qi
- Department of Pathology, Harvard Medical School, Boston, Massachusetts 02115, USA
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7
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Ide T, Brown-Endres L, Chu K, Ongusaha PP, Ohtsuka T, El-Deiry WS, Aaronson SA, Lee SW. GAMT, a p53-inducible modulator of apoptosis, is critical for the adaptive response to nutrient stress. Mol Cell 2009; 36:379-92. [PMID: 19917247 PMCID: PMC2779531 DOI: 10.1016/j.molcel.2009.09.031] [Citation(s) in RCA: 71] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2009] [Revised: 07/11/2009] [Accepted: 09/02/2009] [Indexed: 01/25/2023]
Abstract
The p53 tumor suppressor protein has a well-established role in cell-fate decision-making processes. However, recent discoveries indicate that p53 has a non-tumor-suppressive role. Here we identify guanidinoacetate methyltransferase (GAMT), an enzyme involved in creatine synthesis, as a p53 target gene and a key downstream effector of adaptive response to nutrient stress. We show that GAMT is not only involved in p53-dependent apoptosis in response to genotoxic stress but is important for apoptosis induced by glucose deprivation. Additionally, p53-->GAMT upregulates fatty acid oxidation (FAO) induced by glucose starvation, utilizing this pathway as an alternate ATP-generating energy source. These results highlight that p53-dependent regulation of GAMT allows cells to maintain energy levels sufficient to undergo apoptosis or survival under conditions of nutrient stress. The p53-->GAMT pathway represents a new link between cellular stress responses and processes of creatine synthesis and FAO, demonstrating a further role of p53 in cellular metabolism.
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Affiliation(s)
- Takao Ide
- Cutaneous Biology Research Center, Massachusetts General Hospital and Harvard Medical School, Charlestown, MA, USA
| | - Lauren Brown-Endres
- Cutaneous Biology Research Center, Massachusetts General Hospital and Harvard Medical School, Charlestown, MA, USA
| | - Kiki Chu
- Cutaneous Biology Research Center, Massachusetts General Hospital and Harvard Medical School, Charlestown, MA, USA
| | - Pat P. Ongusaha
- Cutaneous Biology Research Center, Massachusetts General Hospital and Harvard Medical School, Charlestown, MA, USA
| | - Takao Ohtsuka
- Department of Surgery, Saga University Faculty of Medicine, Saga, Japan
| | - Wafik S. El-Deiry
- Department of Medicine, The Abramson Comprehensive Cancer Center, University of Pennsylvania School of Medicine, Philadelphia, PA, USA
| | - Stuart A. Aaronson
- Department of Oncological Sciences, Mount Sinai School of Medicine, New York, NY, USA
| | - Sam W. Lee
- Cutaneous Biology Research Center, Massachusetts General Hospital and Harvard Medical School, Charlestown, MA, USA
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Ongusaha PP, Lee SW. Maximizing tumor cell invasion. Pigment Cell Melanoma Res 2009; 22:148-9. [PMID: 19175753 DOI: 10.1111/j.1755-148x.2009.00542.x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Lee SW, Ongusaha PP, VanHook AM. Science Signaling
Podcast: 02 December 2008. Sci Signal 2008. [DOI: 10.1126/scisignal.148pc13] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Sam Lee and Pat Ongusaha discuss their research on the mechanisms by which ultraviolet B radiation induces cell death.
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Affiliation(s)
- Sam W. Lee
- Cutaneous Biology Research Center, Massachusetts General Hospital and Harvard Medical School, 13th Street, Building 149, Charlestown, MA 02129, USA
| | - Pat P. Ongusaha
- Cutaneous Biology Research Center, Massachusetts General Hospital and Harvard Medical School, 13th Street, Building 149, Charlestown, MA 02129, USA
| | - Annalisa M. VanHook
- Science Signaling, American Association for the Advancement of Science, 1200 New York Avenue, N.W., Washington, DC 20005, USA
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Ongusaha PP, Qi HH, Raj L, Kim YB, Aaronson SA, Davis RJ, Shi Y, Liao JK, Lee SW. Identification of ROCK1 as an upstream activator of the JIP-3 to JNK signaling axis in response to UVB damage. Sci Signal 2008; 1:ra14. [PMID: 19036714 PMCID: PMC2649725 DOI: 10.1126/scisignal.1161938] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Although apoptosis triggered by ultraviolet B (UVB)-mediated activation of the c-Jun N-terminal kinase (JNK) pathway is mediated by both intrinsic and extrinsic pathways, the mechanism of initiation of JNK activation remains obscure. Here, we report the characterization of the JNK-interacting protein 3 (JIP-3) scaffolding protein as an interacting partner of Rho-associated kinase 1 (ROCK1), as determined by tandem affinity protein purification. Upon UVB-induced stress in keratinocytes, ROCK1 was activated, bound to JIP-3, and activated the JNK pathway. Moreover, phosphorylation of JIP-3 by ROCK1 was crucial for the recruitment of JNK. Inhibition of the activity of ROCK1 in keratinocytes resulted in decreased activation of the JNK pathway and thus a reduction in apoptosis. ROCK1(+/-) mice exhibited decreased UVB-mediated activation of JNK and apoptosis relative to wild-type mice. Our findings present a new molecular mechanism by which ROCK1 functions as a UVB sensor that regulates apoptosis, an important event in the prevention of skin cancer.
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Affiliation(s)
- Pat P Ongusaha
- Cutaneous Biology Research Center, Massachusetts General Hospital and Harvard Medical School, Charlestown, MA 02129, USA
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Yang X, Ongusaha PP, Miles PD, Havstad JC, Zhang F, So WV, Kudlow JE, Michell RH, Olefsky JM, Field SJ, Evans RM. Phosphoinositide signalling links O-GlcNAc transferase to insulin resistance. Nature 2008; 451:964-9. [PMID: 18288188 DOI: 10.1038/nature06668] [Citation(s) in RCA: 451] [Impact Index Per Article: 28.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2007] [Accepted: 01/07/2008] [Indexed: 12/14/2022]
Abstract
Glucose flux through the hexosamine biosynthetic pathway leads to the post-translational modification of cytoplasmic and nuclear proteins by O-linked beta-N-acetylglucosamine (O-GlcNAc). This tandem system serves as a nutrient sensor to couple systemic metabolic status to cellular regulation of signal transduction, transcription, and protein degradation. Here we show that O-GlcNAc transferase (OGT) harbours a previously unrecognized type of phosphoinositide-binding domain. After induction with insulin, phosphatidylinositol 3,4,5-trisphosphate recruits OGT from the nucleus to the plasma membrane, where the enzyme catalyses dynamic modification of the insulin signalling pathway by O-GlcNAc. This results in the alteration in phosphorylation of key signalling molecules and the attenuation of insulin signal transduction. Hepatic overexpression of OGT impairs the expression of insulin-responsive genes and causes insulin resistance and dyslipidaemia. These findings identify a molecular mechanism by which nutritional cues regulate insulin signalling through O-GlcNAc, and underscore the contribution of this modification to the aetiology of insulin resistance and type 2 diabetes.
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Affiliation(s)
- Xiaoyong Yang
- Howard Hughes Medical Institute and Gene Expression Laboratory, The Salk Institute for Biological Studies, La Jolla, California 92037, USA
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Das S, Ongusaha PP, Yang YS, Park JM, Aaronson SA, Lee SW. Discoidin domain receptor 1 receptor tyrosine kinase induces cyclooxygenase-2 and promotes chemoresistance through nuclear factor-kappaB pathway activation. Cancer Res 2007; 66:8123-30. [PMID: 16912190 DOI: 10.1158/0008-5472.can-06-1215] [Citation(s) in RCA: 75] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Discoidin domain receptor 1 (DDR1) is a receptor tyrosine kinase activated by various types of collagens and is known to play a role in cell attachment, migration, survival, and proliferation. However, little is known about the molecular mechanism(s) underlying the role of DDR1 in cancer. We report here that DDR1 induces cyclooxygenase-2 (Cox-2) expression resulting in enhanced chemoresistance. Depletion of DDR1-mediated Cox-2 induction using short hairpin RNA (shRNA) results in increased chemosensitivity. We also show that DDR1 activates the nuclear factor-kappaB (NF-kappaB) pathway and blocking this activation by an I kappaB superrepressor mutant results in the ablation of DDR1-induced Cox-2, leading to enhanced chemosensitivity, indicating that DDR1-mediated Cox-2 induction is NF-kappaB dependent. We identify the upstream activating kinases of the NF-kappaB pathway, IKK beta and IKK gamma, as essential for DDR1-mediated NF-kappaB activation, whereas IKK alpha seems to be dispensable. Finally, shRNA-mediated inhibition of DDR1 expression significantly enhanced chemosensitivity to genotoxic drugs in breast cancer cells. Thus, DDR1 signaling provides a novel target for therapeutic intervention with the prosurvival/antiapoptotic machinery of tumor cells.
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Affiliation(s)
- Sanjeev Das
- Cutaneous Biology Research Center, Massachusetts General Hospital and Harvard Medical School, Charlestown, MA 02129, USA
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13
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Brown L, Ongusaha PP, Kim HG, Nuti S, Mandinova A, Lee JW, Khosravi-Far R, Aaronson SA, Lee SW. CDIP, a novel pro-apoptotic gene, regulates TNFalpha-mediated apoptosis in a p53-dependent manner. EMBO J 2007; 26:3410-22. [PMID: 17599062 PMCID: PMC1933410 DOI: 10.1038/sj.emboj.7601779] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2006] [Accepted: 06/08/2007] [Indexed: 11/08/2022] Open
Abstract
We have identified a novel pro-apoptotic p53 target gene named CDIP (Cell Death Involved p53-target). Inhibition of CDIP abrogates p53-mediated apoptotic responses, demonstrating that CDIP is an important p53 apoptotic effector. CDIP itself potently induces apoptosis that is associated with caspase-8 cleavage, implicating the extrinsic cell death pathway in apoptosis mediated by CDIP. siRNA-directed knockdown of caspase-8 results in a severe impairment of CDIP-dependent cell death. In investigating the potential involvement of extrinsic cell death pathway in CDIP-mediated apoptosis, we found that TNF-alpha expression tightly correlates with CDIP expression, and that inhibition of TNF-alpha signaling attenuates CDIP-dependent apoptosis. We also demonstrate that TNF-alpha is upregulated in response to p53 and p53 inducing genotoxic stress, in a CDIP-dependent manner. Consistently, knockdown of TNF-alpha impairs p53-mediated stress-induced apoptosis. Together, these findings support a novel p53 --> CDIP --> TNF-alpha apoptotic pathway that directs apoptosis after exposure of cells to genotoxic stress. Thus, CDIP provides a new link between p53-mediated intrinsic and death receptor-mediated extrinsic apoptotic signaling, providing a novel target for cancer therapeutics aimed at maximizing the p53 apoptotic response of cancer cells to drug therapy.
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Affiliation(s)
- Lauren Brown
- Cutaneous Biology Research Center, Massachusetts General Hospital and Harvard Medical School, Charlestown, MA, USA
| | - Pat P Ongusaha
- Cutaneous Biology Research Center, Massachusetts General Hospital and Harvard Medical School, Charlestown, MA, USA
| | - Hyung-Gu Kim
- Cutaneous Biology Research Center, Massachusetts General Hospital and Harvard Medical School, Charlestown, MA, USA
| | - Shanthy Nuti
- Cutaneous Biology Research Center, Massachusetts General Hospital and Harvard Medical School, Charlestown, MA, USA
| | - Anna Mandinova
- Cutaneous Biology Research Center, Massachusetts General Hospital and Harvard Medical School, Charlestown, MA, USA
| | - Ji Won Lee
- Cutaneous Biology Research Center, Massachusetts General Hospital and Harvard Medical School, Charlestown, MA, USA
| | - Roya Khosravi-Far
- Department of Pathology, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, MA, USA
| | - Stuart A Aaronson
- Department of Oncological Sciences, Mount Sinai School of Medicine, New York, NY, USA
| | - Sam W Lee
- Cutaneous Biology Research Center, Massachusetts General Hospital and Harvard Medical School, Charlestown, MA, USA
- Cutaneous Biology Research Center, Massachusetts General Hospital and Harvard Medical School, Building 149, 13th Street, Charlestown, MA 2129, USA. Tel.: +1 617 726 6691; Fax: +1 617 643 2334; E-mail:
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14
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Ongusaha PP, Kim HG, Boswell SA, Ridley AJ, Der CJ, Dotto GP, Kim YB, Aaronson SA, Lee SW. RhoE is a pro-survival p53 target gene that inhibits ROCK I-mediated apoptosis in response to genotoxic stress. Curr Biol 2006; 16:2466-72. [PMID: 17174923 PMCID: PMC2779528 DOI: 10.1016/j.cub.2006.10.056] [Citation(s) in RCA: 68] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2006] [Revised: 10/25/2006] [Accepted: 10/27/2006] [Indexed: 01/14/2023]
Abstract
The Rho family of GTPases regulates many aspects of cellular behavior through alterations to the actin cytoskeleton . The majority of the Rho family proteins function as molecular switches cycling between the active, GTP-bound and the inactive, GDP-bound conformations . Unlike typical Rho-family proteins, the Rnd subfamily members, including Rnd1, Rnd2, RhoE (also known as Rnd3), and RhoH, are GTPase deficient and are thus expected to be constitutively active . Here, we identify an unexpected role for RhoE/Rnd3 in the regulation of the p53-mediated stress response. We show that RhoE is a transcriptional p53 target gene and that genotoxic stress triggers actin depolymerization, resulting in actin-stress-fiber disassembly through p53-dependent RhoE induction. Silencing of RhoE induction in response to genotoxic stress maintains stress fiber formation and strikingly increases apoptosis, implying an antagonistic role for RhoE in p53-dependent apoptosis. We found that RhoE inhibits ROCK I (Rho-associated kinase I) activity during genotoxic stress and thereby suppresses apoptosis. We demonstrate that the p53-mediated induction of RhoE in response to DNA damage favors cell survival partly through inhibition of ROCK I-mediated apoptosis. Thus, RhoE is anticipated to function by regulating ROCK I signaling to control the balance between cell survival and cell death in response to genotoxic stress.
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Affiliation(s)
- Pat P. Ongusaha
- Cutaneous Biology Research Center, Massachusetts General Hospital and Harvard Medical School, Charlestown, MA 02129
| | - Hyung-Gu Kim
- Cutaneous Biology Research Center, Massachusetts General Hospital and Harvard Medical School, Charlestown, MA 02129
| | - Sarah A. Boswell
- Cutaneous Biology Research Center, Massachusetts General Hospital and Harvard Medical School, Charlestown, MA 02129
| | - Anne J. Ridley
- Ludwig Institute for Cancer Research, Royal Free and University College School of Medicine, London, UK
| | - Channing J. Der
- Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599
| | - G. Paolo Dotto
- Cutaneous Biology Research Center, Massachusetts General Hospital and Harvard Medical School, Charlestown, MA 02129
| | - Young-Bum Kim
- Department of Medicine, Beth Israel Deaconess Medical Center, and, Harvard Medical School, Boston, MA 02215
| | - Stuart A. Aaronson
- Department of Oncological Sciences, Mount Sinai School of Medicine, New York, NY 10029
| | - Sam W. Lee
- Cutaneous Biology Research Center, Massachusetts General Hospital and Harvard Medical School, Charlestown, MA 02129
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15
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Abstract
RhoE, a p53 target gene, was identified as a critical factor for the survival of human keratinocytes in response to UVB. The Rho family of GTPases regulates many aspects of cellular behavior through alterations to the actin cytoskeleton, acting as molecular switches cycling between the active, GTP-bound and the inactive, GDP-bound conformations. Unlike typical Rho family proteins, RhoE (also known as Rnd3) is GTPase-deficient and thus expected to be constitutively active. In this study, we investigated the response of cultured human keratinocyte cells to UVB irradiation. RhoE protein levels increase upon exposure to UVB, and ablation of RhoE induction through small interfering RNA resulted in a significant increase in apoptosis and a reduction in the levels of the pro-survival targets p21, Cox-2, and cyclin D1, as well as an increase of reactive oxygen species levels when compared with control cells. These data indicate that RhoE is a pro-survival factor acting upstream of p38, JNK, p21, and cyclin D1. HaCat cells expressing small interfering RNA to p53 indicate that RhoE functions independently of its known associates, p53 and Rho-associated kinase I (ROCK I). Targeted expression of RhoE in epidermis using skin-specific transgenic mouse model resulted in a significant reduction in the number of apoptotic cells following UVB irradiation. Thus, RhoE induction counteracts UVB-induced apoptosis and may serve as a novel target for the prevention of UVB-induced photodamage regardless of p53 status.
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Affiliation(s)
- Sarah A Boswell
- Dermatology Division, University of Washington, Seattle, Washington 98109
| | - Pat P Ongusaha
- Cutaneous Biology Research Center (CBRC), Massachusetts General Hospital and Harvard Medical School, Charlestown, Massachusetts 02129 and the
| | - Paul Nghiem
- Dermatology Division, University of Washington, Seattle, Washington 98109
| | - Sam W Lee
- Cutaneous Biology Research Center (CBRC), Massachusetts General Hospital and Harvard Medical School, Charlestown, Massachusetts 02129 and the.
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Abstract
Heparin-binding epidermal growth factor-like growth factor (HB-EGF) has been shown to stimulate the growth of a variety of cells in an autocrine or paracrine manner. Although HB-EGF is widely expressed in tumors compared with normal tissue, its contribution to tumorigenicity is unknown. HB-EGF can be produced as a membrane-anchored form (pro-HB-EGF) and later processed to a soluble form (s-HB-EGF), although a significant amount of pro-HB-EGF remains uncleaved on the cell surface. To understand the roles of two forms of HB-EGF in promoting tumor growth, we have studied the effects of HB-EGF expression in the process of tumorigenesis using in vitro and in vivo systems. We demonstrate here that in EJ human bladder cancer cells containing a tetracycline-regulatable s-HB-EGF or pro-HB-EGF expression system, s-HB-EGF expression increased their transformed phenotypes, including growth rate, colony-forming ability, and activation of cyclin D1 promoter, as well as induction of vascular endothelial growth factor in vitro. Moreover, s-HB-EGF or wild-type HB-EGF induced the expression and activities of the metalloproteases, MMP-9 and MMP-3, leading to enhanced cell migration. In vivo studies also demonstrated that tumor cells expressing s-HB-EGF or wild-type HB-EGF significantly enhanced tumorigenic potential in athymic nude mice and exerted an angiogenic effect, increasing the density and size of tumor blood vessels. However, cells expressing solely pro-HB-EGF did not exhibit any significant tumorigenic potential. These findings establish s-HB-EGF as a potent inducer of tumor growth and angiogenesis and suggest that therapeutic intervention aimed at the inhibition of s-HB-EGF functions may be useful in cancer treatment.
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Affiliation(s)
- Pat P Ongusaha
- Cancer Biology Program, Hematology and Oncology Division, Beth Israel Deaconess Medical Center and Harvard Medical School, 4 Blackfan Circle, Boston, MA 02115, USA
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Kim KT, Ongusaha PP, Hong YK, Kurdistani SK, Nakamura M, Lu KP, Lee SW. Function of Drg1/Rit42 in p53-dependent mitotic spindle checkpoint. J Biol Chem 2004; 279:38597-602. [PMID: 15247272 DOI: 10.1074/jbc.m400781200] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
Mutations in the Drg1/RTP/Rit42 gene are commonly identified in hereditary neuropathies of the motor and sensory systems. This gene was also identified as a p53 target gene and a differentiation-related, putative metastatic suppressor gene in human colon and prostate cancer. In this study, we show that the Rit42 protein is a microtubule-associated protein that localizes to the centrosomes and participates in the spindle checkpoint in a p53-dependent manner. When ectopically expressed and exposed to spindle inhibitors, Rit42 inhibited polyploidy in several p53-deficient tumor cell lines and increased the population of cells in mitotic arrest. Blocking endogenous Rit42 expression by small interfering RNA in normal human mammary epithelial cells resulted in the disappearance of astral microtubules, and dividing spindle fiber formation was rarely detected. Moreover, these cells underwent microtubule inhibitor-induced reduplication, leading to a polyploidy state. Our findings imply that Rit42 plays a role in the regulation of microtubule dynamics and the maintenance of euploidy.
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Affiliation(s)
- Kyung-Tae Kim
- Cancer Biology Program, Hematology and Oncology Division, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, Massachusetts 02115, USA
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18
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Ouchi M, Fujiuchi N, Sasai K, Katayama H, Minamishima YA, Ongusaha PP, Deng C, Sen S, Lee SW, Ouchi T. BRCA1 phosphorylation by Aurora-A in the regulation of G2 to M transition. J Biol Chem 2004; 279:19643-8. [PMID: 14990569 DOI: 10.1074/jbc.m311780200] [Citation(s) in RCA: 159] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
Abstract
Aurora-A/BTAK/STK15 localizes to the centrosome in the G(2)-M phase, and its kinase activity regulates the G(2) to M transition of the cell cycle. Previous studies have shown that the BRCA1 breast cancer tumor suppressor also localizes to the centrosome and that BRCA1 inactivation results in loss of the G(2)-M checkpoint. We demonstrate here that Aurora-A physically binds to and phosphorylates BRCA1. Biochemical analysis showed that BRCA1 amino acids 1314-1863 binds to Aurora-A. Site-directed mutagenesis indicated that Ser(308) of BRCA1 is phosphorylated by Aurora-A in vitro. Anti-phospho-specific antibodies against Ser(308) of BRCA1 demonstrated that Ser(308) is phosphorylated in vivo. Phosphorylation of Ser(308) increased in the early M phase when Aurora-A activity also increases; these effects could be abolished by ionizing radiation. Consistent with these observations, acute loss of Aurora-A by small interfering RNA resulted in reduced phosphorylation of BRCA1 Ser(308), and transient infection of adenovirus Aurora-A increased Ser(308) phosphorylation. Mutation of a single phosphorylation site of BRCA1 (S308N), when expressed in BRCA1-deficient mouse embryo fibroblasts, decreased the number of cells in the M phase to a degree similar to that with wild type BRCA1-mediated G(2) arrest induced by DNA damage. We propose that BRCA1 phosphorylation by Aurora-A plays a role in G(2) to M transition of cell cycle.
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Affiliation(s)
- Mutsuko Ouchi
- Derald H. Ruttenberg Cancer Center, The Mount Sinai School of Medicine, New York University, One Gustave L. Levy Place, New York, NY 10029, USA
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Abstract
IFI16 is a member of the HIN-200 family (hematopoietic interferon-inducible nuclear antigens with 200 amino acid repeats) that contains a DNA binding domain, a transcriptional regulatory domain, and DAPIN/PAAD, a protein domain associated with interferon response. It can function as a transcription repressor and directly binds p53. Although the structural and biochemical properties of IFI16 are known, the physiological relevance of these properties in the cellular context is still elusive. Here we report that the inhibition of endogenous IFI16 expression by small interfering RNA (siRNA) induces p21Waf1 mRNA and protein expression through p53 but does not induce pro-apoptotic p53 target genes. This rapid induction of p21 was wild-type p53-dependent and resulted in cell cycle arrest along with a marked reduction of phosphorylated Rb in normally growing cells. We also showed that the repression of IFI16 affects p53 transcriptional activity at the p21 promoter as well as the protein stability of p53 and p21. Our findings identified a new role for IFI16 in modulating p53 function and its target gene regulation in the control of cell cycle regulation.
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Affiliation(s)
- Jennifer C Kwak
- Hematology and Oncology Division, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, Massachusetts 02115, USA
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20
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Ongusaha PP, Ouchi T, Kim KT, Nytko E, Kwak JC, Duda RB, Deng CX, Lee SW. BRCA1 shifts p53-mediated cellular outcomes towards irreversible growth arrest. Oncogene 2003; 22:3749-58. [PMID: 12802282 DOI: 10.1038/sj.onc.1206439] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
The tumor suppressor protein BRCA1 has been shown to enhance p53 transcription, whereas activated p53 represses BRCA1 transcription. To further understand the functional interaction of these proteins, we investigated the role of BRCA1 in p53-induced phenotypes. We found that BRCA1 when subjected to forced expression acts synergistically with wild-type p53, resulting in irreversible growth arrest, as shown by VhD mouse fibroblast cells expressing a temperature-sensitive mutant of p53. Furthermore, reintroduction of both BRCA1 and p53 into BRCA1(-/-)/p53(-/-) mouse embryonic fibroblasts markedly increased the senescence phenotype compared to that induced by p53 alone. In particular, we found that BRCA1 expression attenuated p53-mediated cell death in response to gamma-irradiation. Moreover, microarray screening of 11 000 murine genes demonstrated that a set of genes upregulated by p53 is enhanced by coexpression of BRCA1 and p53, suggesting that BRCA1 and p53 exert a promoter selectivity leading to a specific phenotype. Taken together, our results provide evidence that BRCA1 is involved in p53-mediated growth suppression rather than apoptosis.
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Affiliation(s)
- Pat P Ongusaha
- Cancer Biology Program, Hematology/Oncology Division, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, MA 02115, USA
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Ongusaha PP, Kim JI, Fang L, Wong TW, Yancopoulos GD, Aaronson SA, Lee SW. p53 induction and activation of DDR1 kinase counteract p53-mediated apoptosis and influence p53 regulation through a positive feedback loop. EMBO J 2003; 22:1289-301. [PMID: 12628922 PMCID: PMC151063 DOI: 10.1093/emboj/cdg129] [Citation(s) in RCA: 137] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
DDR1, discoidin domain receptor 1, belongs to a subfamily of tyrosine kinase receptors with an extracellular domain homologous to Dictyostellium discoideum protein discoidin 1. We showed that DDR1 is a direct p53 transcriptional target, and that DNA damage induced a p53-dependent DDR1 response associated with activation of its tyrosine kinase. We further demonstrated that DDR1 activated the MAPK cascade in a Ras-dependent manner. Whereas levels of p53, phosphoserine-15 p53, p21, ARF and Bcl-X(L) were increased in response to exogenous overexpression of activated DDR1, dominant-negative DDR1 inhibited irradiation-induced MAPK activation and p53, phosphoserine-15 p53, as well as induced p21 and DDR1 levels, suggesting that DDR1 functions in a feedforward loop to increase p53 levels and at least some of its effectors. Nonetheless, inhibition of DDR1 function resulted in strikingly increased apoptosis of wild-type p53-containing cells in response to genotoxic stress through a caspase-dependent pathway. These results strongly imply that this p53 response gene must predominately act to alleviate the adverse effects of stress induced by p53 on its target cell.
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Affiliation(s)
| | - Jong-il Kim
- Cancer Biology Program, Beth Israel Deaconess Medical Center, Harvard Institutes of Medicine and Harvard Medical School, Boston, MA 02115,
Derald H. Ruttenberg Cancer Center, Mount Sinai School of Medicine, New York, NY 10029, Oncology Drug Discovery Group, Bristol-Meyer Squibb Pharmaceutical Research Institutes, Princeton, NJ 08543 and Regeneron Pharmaceuticals, Inc., Tarrytown, NY 10591, USA Present address: Department of Biochemistry, College of Medicine, Hallym University, Chunchon, 200-702, Korea Corresponding author e-mail:
| | - Li Fang
- Cancer Biology Program, Beth Israel Deaconess Medical Center, Harvard Institutes of Medicine and Harvard Medical School, Boston, MA 02115,
Derald H. Ruttenberg Cancer Center, Mount Sinai School of Medicine, New York, NY 10029, Oncology Drug Discovery Group, Bristol-Meyer Squibb Pharmaceutical Research Institutes, Princeton, NJ 08543 and Regeneron Pharmaceuticals, Inc., Tarrytown, NY 10591, USA Present address: Department of Biochemistry, College of Medicine, Hallym University, Chunchon, 200-702, Korea Corresponding author e-mail:
| | - Tai W. Wong
- Cancer Biology Program, Beth Israel Deaconess Medical Center, Harvard Institutes of Medicine and Harvard Medical School, Boston, MA 02115,
Derald H. Ruttenberg Cancer Center, Mount Sinai School of Medicine, New York, NY 10029, Oncology Drug Discovery Group, Bristol-Meyer Squibb Pharmaceutical Research Institutes, Princeton, NJ 08543 and Regeneron Pharmaceuticals, Inc., Tarrytown, NY 10591, USA Present address: Department of Biochemistry, College of Medicine, Hallym University, Chunchon, 200-702, Korea Corresponding author e-mail:
| | - George D. Yancopoulos
- Cancer Biology Program, Beth Israel Deaconess Medical Center, Harvard Institutes of Medicine and Harvard Medical School, Boston, MA 02115,
Derald H. Ruttenberg Cancer Center, Mount Sinai School of Medicine, New York, NY 10029, Oncology Drug Discovery Group, Bristol-Meyer Squibb Pharmaceutical Research Institutes, Princeton, NJ 08543 and Regeneron Pharmaceuticals, Inc., Tarrytown, NY 10591, USA Present address: Department of Biochemistry, College of Medicine, Hallym University, Chunchon, 200-702, Korea Corresponding author e-mail:
| | - Stuart A. Aaronson
- Cancer Biology Program, Beth Israel Deaconess Medical Center, Harvard Institutes of Medicine and Harvard Medical School, Boston, MA 02115,
Derald H. Ruttenberg Cancer Center, Mount Sinai School of Medicine, New York, NY 10029, Oncology Drug Discovery Group, Bristol-Meyer Squibb Pharmaceutical Research Institutes, Princeton, NJ 08543 and Regeneron Pharmaceuticals, Inc., Tarrytown, NY 10591, USA Present address: Department of Biochemistry, College of Medicine, Hallym University, Chunchon, 200-702, Korea Corresponding author e-mail:
| | - Sam W. Lee
- Cancer Biology Program, Beth Israel Deaconess Medical Center, Harvard Institutes of Medicine and Harvard Medical School, Boston, MA 02115,
Derald H. Ruttenberg Cancer Center, Mount Sinai School of Medicine, New York, NY 10029, Oncology Drug Discovery Group, Bristol-Meyer Squibb Pharmaceutical Research Institutes, Princeton, NJ 08543 and Regeneron Pharmaceuticals, Inc., Tarrytown, NY 10591, USA Present address: Department of Biochemistry, College of Medicine, Hallym University, Chunchon, 200-702, Korea Corresponding author e-mail:
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Han JA, Kim JI, Ongusaha PP, Hwang DH, Ballou LR, Mahale A, Aaronson SA, Lee SW. P53-mediated induction of Cox-2 counteracts p53- or genotoxic stress-induced apoptosis. EMBO J 2002; 21:5635-44. [PMID: 12411481 PMCID: PMC131088 DOI: 10.1093/emboj/cdf591] [Citation(s) in RCA: 172] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
The identification of transcriptional targets of the tumor suppressor p53 is crucial in understanding mechanisms by which it affects cellular outcomes. Through expression array analysis, we identified cyclooxygenase 2 (Cox-2), whose expression was inducible by wild-type p53 and DNA damage. We also found that p53-induced Cox-2 expression results from p53-mediated activation of the Ras/Raf/MAPK cascade, as demonstrated by suppression of Cox-2 induction in response to p53 by dominant-negative Ras or Raf1 mutants. Furthermore, heparin-binding epidermal growth factor-like growth factor (HB- EGF), a p53 downstream target gene, induced Cox-2 expression, implying that Cox-2 is an ultimate effector in the p53-->HB-EGF-->Ras/Raf/MAPK-->Cox-2 pathway. p53-induced apoptosis was enhanced greatly in Cox-2 knock-out cells as compared with wild-type cells, suggesting that Cox-2 has an abrogating effect on p53-induced apoptosis. Also, a selective Cox-2 inhibitor, NS-398, significantly enhanced genotoxic stress-induced apoptosis in several types of p53+/+ normal human cells, through a caspase-dependent pathway. Together, these results demonstrate that Cox-2 is induced by p53-mediated activation of the Ras/Raf/ERK cascade, counteracting p53-mediated apoptosis. This anti-apoptosis effect may be a mechanism to abate cellular stresses associated with p53 induction.
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Affiliation(s)
- Jeong A. Han
- Cancer Biology Program, Department of Medicine, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, MA 02115,
Pennington Biomedical Research Center, Louisiana State University, Baton Rouge, LA 70808, Department of Veterans Affairs Medical Center, Department of Medicine, University of Tennessee, Memphis, TN 38163 and Derald H.Ruttenberg Cancer Center, Mount Sinai School of Medicine, New York, NY 10029, USA Present address: Department of Biochemistry and Molecular Biology, Kangwon National University College of Medicine, Chuncheon, South Korea Corresponding author e-mail:
| | | | | | - Daniel H. Hwang
- Cancer Biology Program, Department of Medicine, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, MA 02115,
Pennington Biomedical Research Center, Louisiana State University, Baton Rouge, LA 70808, Department of Veterans Affairs Medical Center, Department of Medicine, University of Tennessee, Memphis, TN 38163 and Derald H.Ruttenberg Cancer Center, Mount Sinai School of Medicine, New York, NY 10029, USA Present address: Department of Biochemistry and Molecular Biology, Kangwon National University College of Medicine, Chuncheon, South Korea Corresponding author e-mail:
| | - Leslie R. Ballou
- Cancer Biology Program, Department of Medicine, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, MA 02115,
Pennington Biomedical Research Center, Louisiana State University, Baton Rouge, LA 70808, Department of Veterans Affairs Medical Center, Department of Medicine, University of Tennessee, Memphis, TN 38163 and Derald H.Ruttenberg Cancer Center, Mount Sinai School of Medicine, New York, NY 10029, USA Present address: Department of Biochemistry and Molecular Biology, Kangwon National University College of Medicine, Chuncheon, South Korea Corresponding author e-mail:
| | - Alka Mahale
- Cancer Biology Program, Department of Medicine, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, MA 02115,
Pennington Biomedical Research Center, Louisiana State University, Baton Rouge, LA 70808, Department of Veterans Affairs Medical Center, Department of Medicine, University of Tennessee, Memphis, TN 38163 and Derald H.Ruttenberg Cancer Center, Mount Sinai School of Medicine, New York, NY 10029, USA Present address: Department of Biochemistry and Molecular Biology, Kangwon National University College of Medicine, Chuncheon, South Korea Corresponding author e-mail:
| | - Stuart A. Aaronson
- Cancer Biology Program, Department of Medicine, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, MA 02115,
Pennington Biomedical Research Center, Louisiana State University, Baton Rouge, LA 70808, Department of Veterans Affairs Medical Center, Department of Medicine, University of Tennessee, Memphis, TN 38163 and Derald H.Ruttenberg Cancer Center, Mount Sinai School of Medicine, New York, NY 10029, USA Present address: Department of Biochemistry and Molecular Biology, Kangwon National University College of Medicine, Chuncheon, South Korea Corresponding author e-mail:
| | - Sam W. Lee
- Cancer Biology Program, Department of Medicine, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, MA 02115,
Pennington Biomedical Research Center, Louisiana State University, Baton Rouge, LA 70808, Department of Veterans Affairs Medical Center, Department of Medicine, University of Tennessee, Memphis, TN 38163 and Derald H.Ruttenberg Cancer Center, Mount Sinai School of Medicine, New York, NY 10029, USA Present address: Department of Biochemistry and Molecular Biology, Kangwon National University College of Medicine, Chuncheon, South Korea Corresponding author e-mail:
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23
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Ongusaha PP, Hughes PJ, Davey J, Michell RH. Inositol hexakisphosphate in Schizosaccharomyces pombe: synthesis from Ins(1,4,5)P3 and osmotic regulation. Biochem J 1998; 335 ( Pt 3):671-9. [PMID: 9794810 PMCID: PMC1219831 DOI: 10.1042/bj3350671] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
Schizosaccharomyces pombe extracts synthesize InsP6 (myo-inositol hexaphosphate) from Ins(1,4,5)P3 plus ATP. An S. pombe soluble fraction converts Ins(1,4,5)P3 into Ins(1,4,5,6)P4 and Ins(1,3,4, 5)P4, in a constant ratio of approximately 5:1, and thence to Ins(1, 3,4,5,6)P5 and InsP6. We have purified a soluble Mg2+-dependent kinase of molecular mass approximately 41 kDa that makes Ins(1,4,5, 6)P4 and Ins(1,3,4,5)P4 in the same ratio and also converts Ins(1,4, 5,6)P4 or Ins(1,3,4,5)P4 into Ins(1,3,4,5,6)P5 and InsP6. Of InsP3 isomers other than Ins(1,4,5)P3, only the non-biological molecule Ins(1,4,6)P3 potently 'competed' with all steps in conversion of Ins(1,4,5)P3 into InsP6. Examination of molecular graphics representations allowed us to draw tentative conclusions about the environment needed for an hydroxyl group to be phosphorylated by this kinase and to predict successfully that the purified kinase would phosphorylate the 5-hydroxyl of Ins(1,4,6)P3. S. pombe that have been cultured with [3H]inositol contains a variety of 3H-labelled inositol polyphosphates, with Ins(1,4,5)P3 and InsP6 the most prominent, and the InsP6 concentration quickly increases in hyper-osmotically stressed S. pombe. This yeast therefore contains InsP6 and Ins(1,4,5)P3 as normal constituents, makes more InsP6 when hyper-osmotically stressed and contains a versatile inositol polyphosphate kinase that synthesizes InsP6 from Ins(1,4,5)P3.
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Affiliation(s)
- P P Ongusaha
- Centre for Clinical Research in Immunology and Signalling, University of Birmingham, Birmingham B15 2TT, UK
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24
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Affiliation(s)
- P P Ongusaha
- CCRIS and School of Biochemistry, University of Birmingham, UK
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