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Ke R, Kumar S, Singh SK, Rana A, Rana B. Molecular insights into the role of mixed lineage kinase 3 in cancer hallmarks. Biochim Biophys Acta Rev Cancer 2024; 1879:189157. [PMID: 39032538 DOI: 10.1016/j.bbcan.2024.189157] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2023] [Revised: 07/14/2024] [Accepted: 07/17/2024] [Indexed: 07/23/2024]
Abstract
Mixed-lineage kinase 3 (MLK3) is a serine/threonine kinase of the MAPK Kinase kinase (MAP3K) family that plays critical roles in various biological processes, including cancer. Upon activation, MLK3 differentially activates downstream MAPKs, such as JNK, p38, and ERK. In addition, it regulates various non-canonical signaling pathways, such as β-catenin, AMPK, Pin1, and PAK1, to regulate cell proliferation, apoptosis, invasion, and metastasis. Recent studies have also uncovered other potentially diverse roles of MLK3 in malignancy, which include metabolic reprogramming, cancer-associated inflammation, and evasion of cancer-related immune surveillance. The role of MLK3 in cancer is complex and cancer-specific, and an understanding of its function at the molecular level aligned specifically with the cancer hallmarks will have profound therapeutic implications for diagnosing and treating MLK3-dependent cancers. This review summarizes the current knowledge about the effect of MLK3 on the hallmarks of cancer, providing insights into its potential as a promising anticancer drug target.
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Affiliation(s)
- Rong Ke
- Department of Surgery, Division of Surgical Oncology, University of Illinois at Chicago, Chicago, IL 60612, USA; Department of Biochemistry and Molecular Genetics, University of Illinois at Chicago, Chicago, IL 60607, USA
| | - Sandeep Kumar
- Department of Surgery, Division of Surgical Oncology, University of Illinois at Chicago, Chicago, IL 60612, USA; University of Illinois Hospital and Health Sciences System Cancer Center, University of Illinois at Chicago, Chicago, IL 60612, USA
| | - Sunil Kumar Singh
- Department of Surgery, Division of Surgical Oncology, University of Illinois at Chicago, Chicago, IL 60612, USA
| | - Ajay Rana
- Department of Surgery, Division of Surgical Oncology, University of Illinois at Chicago, Chicago, IL 60612, USA; University of Illinois Hospital and Health Sciences System Cancer Center, University of Illinois at Chicago, Chicago, IL 60612, USA; Jesse Brown VA Medical Center, Chicago, IL 60612, USA
| | - Basabi Rana
- Department of Surgery, Division of Surgical Oncology, University of Illinois at Chicago, Chicago, IL 60612, USA; University of Illinois Hospital and Health Sciences System Cancer Center, University of Illinois at Chicago, Chicago, IL 60612, USA; Jesse Brown VA Medical Center, Chicago, IL 60612, USA.
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2
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Ying C, Dai J, Fan G, Zhou Z, Gan T, Zhang Y, Song Y, Zhou X. Ras-Related C3 Botulinum Toxin Substrate 1 Combining With the Mixed Lineage Kinase 3- Mitogen-Activated Protein Kinase 7- c-Jun N-Terminal Kinase Signaling Module Accelerates Diabetic Nephropathy. Front Physiol 2021; 12:679166. [PMID: 34194338 PMCID: PMC8236718 DOI: 10.3389/fphys.2021.679166] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2021] [Accepted: 05/04/2021] [Indexed: 12/12/2022] Open
Abstract
Ras-related C3 botulinum toxin substrate 1 (RAC1) activation plays a vital role in diabetic nephropathy (DN), but the exact mechanism remains unclear. In this study, we attempted to elucidate the precise mechanism of how RAC1 aggravates DN through cellular and animal experiments. In this study, DN was induced in mice by intraperitoneal injection of streptozotocin (STZ, 150mg/kg), and the RAC1 inhibitor NSC23766 was administered by tail vein injection. Biochemical indicators, cell proliferation and apoptosis, and morphological changes in the kidney were detected. The expression of phosphorylated c-Jun N-terminal kinase (p-JNK), nuclear factor-κB (NF-κB), and cleaved caspase-3 and the interaction between RAC1 and the mixed lineage kinase 3 (MLK3)-mitogen-activated protein kinase 7 (MKK7)-JNK signaling module were determined. Furthermore, the colocalization and direct co-interaction of RAC1 and MLK3 were confirmed. Our results showed that RAC1 accelerates renal damage and increases the expression of p-JNK, NF-κB, and cleaved caspase-3. However, inhibition of RAC1 ameliorated DN by downregulating p-JNK, NF-κB, and cleaved caspase-3. Also, RAC1 promoted the assembly of MLK3-MKK7-JNK, and NSC23766 blocked the interaction between RAC1 and MLK3-MKK7-JNK and inhibited the assembly of the MLK3-MKK7-JNK signaling module. Furthermore, RAC1 was combined with MLK3 directly, but the RAC1 Y40C mutant inhibited the interaction between RAC1 and MLK3. We demonstrated that RAC1 combining with MLK3 activates the MLK3-MKK7-JNK signaling module, accelerating DN occurrence and development, and RAC1 Y40 is an important site for binding of RAC1 to MLK3. This study illustrates the cellular and molecular mechanisms of how RAC1 accelerates DN and provides evidence of DN-targeted therapy.
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Affiliation(s)
- Changjiang Ying
- Department of Endocrinology, Affiliated Hospital of Xuzhou Medical University, Xuzhou, China
| | - Jiao Dai
- The Graduate School, Xuzhou Medical University, Xuzhou, China
| | - Gaoxia Fan
- The Graduate School, Xuzhou Medical University, Xuzhou, China
| | - Zhongyuan Zhou
- The Graduate School, Xuzhou Medical University, Xuzhou, China
| | - Tian Gan
- Department of Endocrinology, Affiliated Hospital of Xuzhou Medical University, Xuzhou, China
| | - Yusheng Zhang
- The Graduate School, Xuzhou Medical University, Xuzhou, China
| | - Yuanjian Song
- Department of Genetics, School of Life Sciences, Xuzhou Medical University, Xuzhou, China
| | - Xiaoyan Zhou
- Department of Genetics, School of Life Sciences, Xuzhou Medical University, Xuzhou, China
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3
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Li CH, Liao PL, Shyu MK, Liu CW, Kao CC, Huang SH, Cheng YW, Kang JJ. Zinc oxide nanoparticles-induced intercellular adhesion molecule 1 expression requires Rac1/Cdc42, mixed lineage kinase 3, and c-Jun N-terminal kinase activation in endothelial cells. Toxicol Sci 2012; 126:162-72. [PMID: 22166487 DOI: 10.1093/toxsci/kfr331] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2023] Open
Abstract
The explosive development of nanotechnology has caused an increase in unintended biohazards in humans and in the ecosystem. Similar to particulate matter, nanoparticles (NPs) are strongly correlated with the increase in incidences of cardiovascular diseases, yet the mechanisms behind this correlation remain unclear. Within the testing concentrations of 0.1-10 μg/ml, which did not cause a marked drop in cell viability, zinc oxide NPs (ZnO-NPs) induced intercellular adhesion molecule-1 (ICAM-1) messenger RNA, and protein expression in both concentration- and time-dependent manner in treated human umbilical vein endothelial cells (HUVECs). ZnO-NPs treatment cause the activation of Ras-related C3 botulinum toxin substrate 1 (Rac1)/cell division control protein 42 homolog (Cdc42) and protein accumulation of mixed lineage kinase 3 (MLK3), followed by c-Jun N-terminal kinase (JNK) and transcription factor c-Jun activation. Induction of ICAM-1 and phosphorylation of JNK and c-Jun could be inhibited by either JNK inhibitor SP600125 or Rac guanosine triphosphatase inhibitor NSC23766 pretreatment. In addition, pretreatment with NSC23766 significantly reduced MLK3 accumulation, suggesting the involvement of Rac1/Cdc42-MLK3-JNK-c-Jun signaling in the regulation of ZnO-NPs-induced ICAM-1 expression, whereas these signaling factors were not activated in zinc oxide microparticles (ZnO-MPs)-treated HUVECs. The increase of ICAM-1 expression on ZnO-NPs-treated HUVECs enables leukocytes to adhere and has been identified as an indicator of vascular inflammation. Our data are essential for safety evaluation of the clinical usage of ZnO-NPs in daily supplements, cosmetics, and biomedicines.
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Affiliation(s)
- Ching-Hao Li
- Institute of Toxicology, College of Medicine, National Taiwan University, Taipei, Taiwan
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4
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Kashuba VI, Grigorieva EV, Kvasha SM, Pavlova TV, Grigoriev V, Protopopov A, Kharchenko O, Gizatullin R, Rynditch AV, Zabarovsky ER. Cloning and Initial Functional Characterization of Mlk4α and Mlk4β. GENOMICS INSIGHTS 2011. [PMID: 26217104 PMCID: PMC4510602 DOI: 10.4137/gei.s6092] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
We have cloned a novel human mixed-lineage kinase gene, MLK4. Two alternatively spliced forms, MLK4α (580 aa) and MLK4β (1036 aa), have been identified and mapped to chromosomal band 1q42. MLK4 shows high amino acid homology to the kinase catalytic domain of MLK3 (72%), MLK1 (71%) and MLK2 (69%). Strong expression of MLK4 was detected in the human pancreas and kidneys. pCMV-MLK4β c-myc-tagged protein (human) was expressed in the cytoplasm and nucleus of transiently transfected COS-1 cells, while pCMV-MLK4α c-myc-tagged protein (human) was expressed in cytoplasm only. Both MLK4 isoforms reduced the colony formation ability of MCF7 cells by 85%-95% and almost totally suppressed cell proliferation in the CyQUANT cell proliferation assay. Human pCMV-MLK4β transgenic mice expressed the MLK4β in all tissues examined but no phenotypic abnormalities were observed. Thus, in this work, we present the cloning and sequencing of MLK4α and MLK4β for the first time; the data obtained suggest that MLK4 may function as a MAP kinase.
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Affiliation(s)
- Vladimir I Kashuba
- Department of Microbiology, Tumor and Cell Biology, Department of Clinical Science and Education, Södersjukhuset, Karolinska Institute, Stockholm, 17177, Sweden. ; Institute of Molecular Biology and Genetics, Ukrainian National Academy of Sciences, Kiev, 03143, Ukraine
| | - Elvira V Grigorieva
- Department of Microbiology, Tumor and Cell Biology, Department of Clinical Science and Education, Södersjukhuset, Karolinska Institute, Stockholm, 17177, Sweden. ; Institute of Molecular Biology and Biophysics, Siberian Division of Russian Academy of Medical Sciences, Novosibirsk, 630117, Russia
| | - Sergei M Kvasha
- Institute of Molecular Biology and Genetics, Ukrainian National Academy of Sciences, Kiev, 03143, Ukraine
| | - Tatiana V Pavlova
- Department of Microbiology, Tumor and Cell Biology, Department of Clinical Science and Education, Södersjukhuset, Karolinska Institute, Stockholm, 17177, Sweden. ; Engelhardt Institute of Molecular Biology, Russian Academy of Sciences, Moscow, 119991, Russia
| | | | - Alexei Protopopov
- Department of Microbiology, Tumor and Cell Biology, Department of Clinical Science and Education, Södersjukhuset, Karolinska Institute, Stockholm, 17177, Sweden
| | - Olga Kharchenko
- Department of Microbiology, Tumor and Cell Biology, Department of Clinical Science and Education, Södersjukhuset, Karolinska Institute, Stockholm, 17177, Sweden. ; Pavlov Institute of Physiology, Russian Academy of Sciences, St. Petersburg, 199034, Russia
| | - Rinat Gizatullin
- Department of Microbiology, Tumor and Cell Biology, Department of Clinical Science and Education, Södersjukhuset, Karolinska Institute, Stockholm, 17177, Sweden
| | - Alla V Rynditch
- Institute of Molecular Biology and Genetics, Ukrainian National Academy of Sciences, Kiev, 03143, Ukraine
| | - Eugene R Zabarovsky
- Department of Microbiology, Tumor and Cell Biology, Department of Clinical Science and Education, Södersjukhuset, Karolinska Institute, Stockholm, 17177, Sweden. ; Engelhardt Institute of Molecular Biology, Russian Academy of Sciences, Moscow, 119991, Russia
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Kobayashi T, Inoue T, Shimizu Y, Terada N, Maeno A, Kajita Y, Yamasaki T, Kamba T, Toda Y, Mikami Y, Yamada T, Kamoto T, Ogawa O, Nakamura E. Activation of Rac1 is closely related to androgen-independent cell proliferation of prostate cancer cells both in vitro and in vivo. Mol Endocrinol 2010; 24:722-34. [PMID: 20203103 PMCID: PMC5417531 DOI: 10.1210/me.2009-0326] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2009] [Accepted: 01/26/2010] [Indexed: 11/19/2022] Open
Abstract
We and others previously showed that signaling through cSrc or atypical protein kinase C (aPKC) pathway regulates the proliferation of prostate cancer cells and is associated with their progression to castrate-resistance in vivo. However, the interrelation of these two kinases has been largely unexplored. In the present study, we show that androgen-induced activation of cSrc regulates the activity of aPKC through the small molecular weight G protein Rac1 in androgen-dependent LNCaP cells. Knockdown of cSrc in those cells reduces the phosphorylation of aPKC and the abundance of activated form of Rac1. Additionally, the treatment of those cells with Rac1 inhibitor repressed cell cycle progression at G(1)/S transition. In fact, forced expression of a constitutively active Rac1 mutant in LNCaP cells promoted cell proliferation under androgen-depleted conditions both in vitro and in vivo. Moreover, LNCaP C4-2 and AILNCaP cells, the syngeneic androgen-independent sublines from LNCaP cells, harbored abundant Rac1-GTP. Importantly, the inhibition of Rac1 suppressed cell proliferation and induced apoptotic cell death in all prostate cancer cell lines tested irrespective of their androgen-dependence. In immunohistochemical evaluation of tumor specimens from prostate cancer patients, Rac1 pathway appeared to be activated in the majority of castrate-resistant diseases. Collectively, our present results both in vitro and in vivo highly implicate that Rac1 can be a potential therapeutic target for patients with advanced prostate cancer, especially those with castrate-resistant status.
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Affiliation(s)
- Takashi Kobayashi
- Department of Urology, Kyoto University, Graduate School of Medicine, Kyoto, Japan
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6
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Gerber MA, Bahr SM, Gutmann DH. Protein 4.1B/differentially expressed in adenocarcinoma of the lung-1 functions as a growth suppressor in meningioma cells by activating Rac1-dependent c-Jun-NH(2)-kinase signaling. Cancer Res 2006; 66:5295-303. [PMID: 16707455 DOI: 10.1158/0008-5472.can-05-1628] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Meningiomas are the second most common brain tumor in adults, yet comparatively little is presently known about the dysregulated growth control pathways involved in their formation and progression. One of the most frequently observed genetic changes in benign meningioma involves loss of protein 4.1B expression. Previous studies from our laboratory have shown that protein 4.1B growth suppression in meningioma is associated with the activation of the c-Jun-NH(2)-kinase (JNK) pathway and requires localization of a small unique region (U2 domain) of protein 4.1B to the plasma membrane. To define the relationship between protein 4.1B expression and JNK activation, as well as to determine the mechanism of JNK activation by protein 4.1B, we used a combination of genetic and pharmacologic approaches. In this report, we show that protein 4.1B/differentially expressed in adenocarcinoma of the lung-1 (DAL-1) expression in meningioma cells in vitro results in JNK activation, which requires the sequential activation of Src, Rac1, and JNK. In addition, inhibition of Rac1 or JNK activation abrogates protein 4.1B/DAL-1 growth suppression and cyclin A regulation. Last, protein 4.1B/DAL-1 regulation of this critical growth control pathway in meningioma cells requires the presence of the U2 domain. Collectively, these observations provide the first mechanistic insights into the function of protein 4.1B as a growth regulator in meningioma cells.
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Affiliation(s)
- Mark A Gerber
- Department of Neurology, Washington University School of Medicine, St. Louis, Missouri 63110, USA
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7
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Cha H, Dangi S, Machamer CE, Shapiro P. Inhibition of mixed-lineage kinase (MLK) activity during G2-phase disrupts microtubule formation and mitotic progression in HeLa cells. Cell Signal 2006; 18:93-104. [PMID: 15923109 PMCID: PMC2835151 DOI: 10.1016/j.cellsig.2005.03.028] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2005] [Revised: 03/18/2005] [Accepted: 03/18/2005] [Indexed: 10/25/2022]
Abstract
The mixed-lineage kinases (MLK) are serine/threonine protein kinases that regulate mitogen-activated protein (MAP) kinase signaling pathways in response to extracellular signals. Recent studies indicate that MLK activity may promote neuronal cell death through activation of the c-Jun NH2-terminal kinase (JNK) family of MAP kinases. Thus, inhibitors of MLK activity may be clinically useful for delaying the progression of neurodegenerative diseases, such as Parkinson's. In proliferating non-neuronal cells, MLK may have the opposite effect of promoting cell proliferation. In the current studies we examined the requirement for MLK proteins in regulating cell proliferation by examining MLK function during G2 and M-phase of the cell cycle. The MLK inhibitor CEP-11004 prevented HeLa cell proliferation by delaying mitotic progression. Closer examination revealed that HeLa cells treated with CEP-11004 during G2-phase entered mitosis similar to untreated G2-phase cells. However, CEP-11004 treated cells failed to properly exit mitosis and arrested in a pro-metaphase state. Partial reversal of the CEP-11004 induced mitotic arrest could be achieved by overexpression of exogenous MLK3. The effects of CEP-11004 treatment on mitotic events included the inhibition of histone H3 phosphorylation during prophase and prior to nuclear envelope breakdown and the formation of aberrant mitotic spindles. These data indicate that MLK3 might be a unique target to selectively inhibit transformed cell proliferation by disrupting mitotic spindle formation resulting in mitotic arrest.
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Affiliation(s)
- Hyukjin Cha
- Department of Pharmaceutical Sciences, University of Maryland, School of Pharmacy Baltimore, Maryland, USA
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8
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Boureux A, Furstoss O, Simon V, Roche S. Abl tyrosine kinase regulates a Rac/JNK and a Rac/Nox pathway for DNA synthesis and Myc expression induced by growth factors. J Cell Sci 2005; 118:3717-26. [PMID: 16076903 DOI: 10.1242/jcs.02491] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
The cytoplasmic tyrosine kinase Abl is a Src substrate required for platelet-derived growth factor (PDGF) receptor signaling leading to Myc expression and DNA synthesis. Abl targets are, however, ill defined. Here we report that the small GTPase Rac is an important effector of its mitogenic function. PDGF-induced Rac activation was impaired in cells with inactive Abl and active Rac overcame the mitogenic defects found in these cells. Rac function required both a Jun N-terminal kinase (JNK) and a NADPH oxidase (Nox) pathway. Furthermore, co-activation of JNK and Nox were sufficient to mimic the Rac mitogenic rescue. Abl also regulated PDGF-induced JNK and Nox activation. Finally, we found that Myc is an important target of this signaling cascade: Myc induction was sensitive to small inhibitors of JNK and Nox activities and forced expression of Myc overcame the G1 block induced by dominant interfering mutants of mitogen-activated protein kinase kinase 4 (MKK4) and Nox2 activating subunit. We concluded that cytoplasmic Abl operates on a Rac/JNK and a Rac/Nox pathway for PDGF-induced Myc induction and DNA synthesis.
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Affiliation(s)
- Anthony Boureux
- CRBM, CNRS FRE2593, 1919 route de Mende, 34293 Montpellier Cedex 05, France
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9
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Bae GU, Kim YK, Kwon HK, Park JW, Lee EK, Paek SJ, Choi WS, Jung ID, Lee HY, Cho EJ, Lee HW, Han JW. Hydrogen peroxide mediates Rac1 activation of S6K1. Exp Cell Res 2004; 300:476-84. [PMID: 15475011 DOI: 10.1016/j.yexcr.2004.07.013] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2004] [Revised: 07/19/2004] [Indexed: 11/25/2022]
Abstract
We previously reported that hydrogen peroxide (H2O2) mediates mitogen activation of ribosomal protein S6 kinase 1 (S6K1) which plays an important role in cell proliferation and growth. In this study, we investigated a possible role of H2O2 as a molecular linker in Rac1 activation of S6K1. Overexpression of recombinant catalase in NIH-3T3 cells led to the drastic inhibition of H2O2 production by PDGF, which was accompanied by a decrease in S6K1 activity. Similarly, PDGF activation of S6K1 was significantly inhibited by transient transfection or stable transfection of the cells with a dominant-negative Rac1 (Rac1N17), while overexpression of constitutively active Rac1 (Rac1V12) in the cells led to an increase in basal activity of S6K1. In addition, stable transfection of Rat2 cells with Rac1N17 dramatically attenuated the H2O2 production by PDGF as compared with that in the control cells. In contrast, Rat2 cells stably transfected with Rac1V12 produced high level of H2O2 in the absence of PDGF, comparable to that in the control cells stimulated with PDGF. More importantly, elimination of H2O2 produced in Rat2 cells overexpressing Rac1V12 inhibited the Rac1V12 activation of S6K1, indicating the possible role of H2O2 as a mediator in the activation of S6K1 by Rac1. However, H2O2 could be also produced via other pathway, which is independent of Rac1 or PI3K, because in Rat2 cells stably transfected with Rac1N17, H2O2 could be produced by arsenite, which has been shown to be a stimulator of H2O2 production. Taken together, these results suggest that H2O2 plays a pivotal role as a mediator in Rac1 activation of S6K1.
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Affiliation(s)
- Gyu-Un Bae
- College of Pharmacy, Sungkyunkwan University, Suwon 440-746, South Korea
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10
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Berven LA, Willard FS, Crouch MF. Role of the p70(S6K) pathway in regulating the actin cytoskeleton and cell migration. Exp Cell Res 2004; 296:183-95. [PMID: 15149849 DOI: 10.1016/j.yexcr.2003.12.032] [Citation(s) in RCA: 109] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2003] [Revised: 11/24/2003] [Indexed: 02/01/2023]
Abstract
We have examined the role of endogenous 70-kDa S6 kinase (p70(S6K)) in actin cytoskeletal organization and cell migration in Swiss 3T3 fibroblasts. Association of p70(S6K) with the actin cytoskeleton was demonstrated by cosedimentation of p70(S6K) with F-actin and by subcellular fractionation in which p70(S6K) activity was measured in the F-actin cytoskeletal fraction. Immunocytochemical studies showed that p70(S6K), Akt1, PDK1, and p85 phosphoinositide 3-kinase (PI 3-kinase) were localized to the actin arc, a caveolin-enriched cytoskeletal structure located at the leading edge of migrating cells. Using a phospho-specific antibody to mammalian target of rapamycin (mTOR), we find that activated mTOR is enriched at the actin arc, suggesting that activation of the p70(S6K) signaling pathway is important to cell migration. Using the actin arc to assess migration, epidermal growth factor (EGF) stimulation was found to induce actin arc formation, an effect that was blocked by rapamycin treatment. We show further that actin stress fibers may function to down-regulate p70(S6K). Fibronectin stimulated stress fiber formation in the absence of growth factors and caused an inactivation of p70(S6K). Conversely, cytochalasin D and the Rho kinase inhibitor Y-27632, both of which cause stress fiber disruption, increased p70(S6K) activity. These studies provide evidence that the p70(S6K) pathway is important for signaling at two F-actin microdomains in cells and regulates cell migration.
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Affiliation(s)
- Leise A Berven
- Molecular Signalling Group, Division of Neuroscience, John Curtin School of Medical Research, Australian National University, Canberra, Australia
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11
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Cho YY, Bode AM, Mizuno H, Choi BY, Choi HS, Dong Z. A novel role for mixed-lineage kinase-like mitogen-activated protein triple kinase alpha in neoplastic cell transformation and tumor development. Cancer Res 2004; 64:3855-64. [PMID: 15172994 DOI: 10.1158/0008-5472.can-04-0201] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
Previously, no member of the mixed-lineage kinase (MLK) protein family was known to function as an oncogene. Here, we demonstrate that MLK-like mitogen-activated protein triple kinase (MLTK)-alpha, a member of the MLK family, induced neoplastic cell transformation and tumorigenesis in athymic nude mice. Introduction of small interference RNA (siRNA)-MLTK-alpha into MLTK-alpha-overexpressing cells dramatically suppressed cell transformation. Nuclear accumulation of the pHisG-MLTK-alpha fusion protein was observed after epidermal growth factor or 12-O-tetradecanoylphorbol-13-acetate treatment. Phosphorylation of downstream mitogen-activated protein kinase-targeted transcription factors including c-Myc, Elk-1, c-Jun, and activating transcription factor (ATF) 2 was also differentially enhanced in MLTK-alpha-overexpressing cells exposed to epidermal growth factor or 12-O-tetradecanoylphorbol-13-acetate stimulation compared with cells expressing mock vector or siRNA-MLTK-alpha. Very importantly, MLTK-alpha-overexpressing cells formed fibrosarcomas when injected s.c. into athymic nude mice, whereas almost no tumor formation was observed in mice that received injections of mock or siRNA-MLTK-alpha stably transfected cells. These results are the first to indicate that MLTK-alpha plays a key role in neoplastic cell transformation and cancer development.
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Affiliation(s)
- Yong-Yeon Cho
- Hormel Institute University of Minnesota, Austin, Minnesota 55912, USA
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12
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Coleman ML, Marshall CJ, Olson MF. RAS and RHO GTPases in G1-phase cell-cycle regulation. Nat Rev Mol Cell Biol 2004; 5:355-66. [PMID: 15122349 DOI: 10.1038/nrm1365] [Citation(s) in RCA: 266] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Affiliation(s)
- Mathew L Coleman
- Abramson Family Cancer Research Institute, BRB II/III, 421 Curie Boulevard, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6160, USA
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13
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Figueroa C, Tarras S, Taylor J, Vojtek AB. Akt2 negatively regulates assembly of the POSH-MLK-JNK signaling complex. J Biol Chem 2003; 278:47922-7. [PMID: 14504284 DOI: 10.1074/jbc.m307357200] [Citation(s) in RCA: 71] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
We demonstrate that POSH, a scaffold for the JNK signaling pathway, binds to Akt2. A POSH mutant that is unable to bind Akt2 (POSH W489A) exhibits enhanced-binding to MLK3, and this increase in binding is accompanied by increased activation of the JNK signaling pathway. In addition, we show that the association of MLK3 with POSH is increased upon inhibition of the endogenous phosphatidylinositol 3-kinase/Akt signaling pathway. Thus, the assembly of an active JNK signaling complex by POSH is negatively regulated by Akt2. Further, the level of Akt-phosphorylated MLK3 is reduced in cells expressing the Akt2 binding domain of POSH, which acts as a dominant interfering protein. Taken together, our results support a model in which Akt2 binds to a POSH-MLK-MKK-JNK complex and phosphorylates MLK3; phosphorylation of MLK3 by Akt2 results in the disassembly of the JNK complex bound to POSH and down-regulation of the JNK signaling pathway.
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Affiliation(s)
- Claudia Figueroa
- Department of Biological Chemistry, University of Michigan, Ann Arbor, Michigan 48109, USA
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Abstract
A novel region of amplification in breast tumors was recently identified on chromosome 17q23. Extensive mapping of the amplicon by Southern blotting and fluorescence in situ hybridization (FISH) in breast cancer cell lines determined that the amplicon can be up to 4 Mbp in size and may contain 50 genes. Copy number analysis at 50-75 kb resolution in breast cancer cell lines and breast tumors identified several independently amplified regions within the amplicon, suggesting that a number of genes are selected for amplification because they independently contribute to tumor formation and progression. Support for this hypothesis comes from studies demonstrating that many of the amplified genes are over-expressed in breast cancer cell lines and tumors, and that the RPS6KB1, TBX2, and PPM1D genes from the region, that are amplified and over-expressed in breast tumors and cell lines, contribute to tumor formation and/or tumor progression. In this review we summarize the structural studies of the amplicon that have been carried out, we outline the evidence implicating the RPS6KB1, TBX2, and PPM1D genes as oncogenes, and we describe some of the other candidate oncogenes from the region.
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Swenson KI, Winkler KE, Means AR. A new identity for MLK3 as an NIMA-related, cell cycle-regulated kinase that is localized near centrosomes and influences microtubule organization. Mol Biol Cell 2003; 14:156-72. [PMID: 12529434 PMCID: PMC140235 DOI: 10.1091/mbc.e02-02-0115] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2002] [Revised: 10/04/2002] [Accepted: 10/09/2002] [Indexed: 02/02/2023] Open
Abstract
Although conserved counterparts for most proteins involved in the G(2)/M transition of the cell cycle have been found in all eukaryotes, a notable exception is the essential but functionally enigmatic fungal kinase NIMA. While a number of vertebrate kinases have been identified with catalytic domain homology to NIMA, none of these resemble NIMA within its extensive noncatalytic region, a region critical for NIMA function in Aspergillus nidulans. We used a bioinformatics approach to search for proteins with homology to the noncatalytic region of NIMA and identified mixed lineage kinase 3 (MLK3). MLK3 has been proposed to serve as a component in MAP kinase cascades, particularly those resulting in the activation of the c-Jun N-terminal kinase (JNK). Here we describe the first in-depth study of endogenous MLK3 and report that, like NIMA, MLK3 phosphorylation and activity are enhanced during G(2)/M, whereas JNK remains inactive. Coincident with the G(2)/M transition, a period marked by dramatic reorganization of the cytoplasmic microtubule network, endogenous MLK3 transiently disperses away from the centrosome and centrosomal-proximal sites where it is localized during interphase. Furthermore, when overexpressed, MLK3, like NIMA, localizes to the centrosomal region, induces profound disruption of cytoplasmic microtubules and a nuclear distortion phenotype that differs from mitotic chromosome condensation. Cellular depletion of MLK3 protein using siRNA technology results in an increased sensitivity to the microtubule-stabilizing agent taxol. Our studies suggest a new role for MLK3, separable from its function in the JNK pathway, that may contribute to promoting microtubule instability, a hallmark of M phase entry.
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Affiliation(s)
- Katherine I Swenson
- Department of Pharmacology and Cancer Biology, Duke University Medical Center, Durham, North Carolina 27710, USA
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Wennerberg K, Ellerbroek SM, Liu RY, Karnoub AE, Burridge K, Der CJ. RhoG signals in parallel with Rac1 and Cdc42. J Biol Chem 2002; 277:47810-7. [PMID: 12376551 DOI: 10.1074/jbc.m203816200] [Citation(s) in RCA: 90] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
RhoG is a member of the Rho family of small GTPases and shares high sequence identity with Rac1 and Cdc42. Previous studies suggested that RhoG mediates its effects through activation of Rac1 and Cdc42. To further understand the mechanism of RhoG signaling, we studied its potential activation pathways, downstream signaling properties, and functional relationship to Rac1 and Cdc42 in vivo. First, we determined that RhoG was regulated by guanine nucleotide exchange factors that also activate Rac and/or Cdc42. Vav2 (which activates RhoA, Rac1, and Cdc42) and to a lesser degree Dbs (which activates RhoA and Cdc42) activated RhoG in vitro. Thus, RhoG may be activated concurrently with Rac1 and Cdc42. Second, some effectors of Rac/Cdc42 (IQGAP2, MLK-3, PLD1), but not others (e.g. PAKs, POSH, WASP, Par-6, IRSp53), interacted with RhoG in a GTP-dependent manner. Third, consistent with this differential interaction with effectors, activated RhoG stimulated some (JNK and Akt) but not other (SRF and NF-kappaB) downstream signaling targets of activated Rac1 and Cdc42. Finally, transient transduction of a tat-tagged Rac1(17N) dominant-negative fusion protein inhibited the induction of lamellipodia by the Rac-specific activator, Tiam1, but not by activated RhoG. Together, these data argue that RhoG function is mediated by signals independent of Rac1 and Cdc42 activation and instead by direct utilization of a subset of common effectors.
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Affiliation(s)
- Krister Wennerberg
- Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, North Carolina 27599-7295, USA.
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Chan W, Kozma R, Yasui Y, Inagaki M, Leung T, Manser E, Lim L. Vimentin intermediate filament reorganization by Cdc42: involvement of PAK and p70 S6 kinase. Eur J Cell Biol 2002; 81:692-701. [PMID: 12553669 DOI: 10.1078/0171-9335-00281] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Rho family GTPases play a major role in actin cytoskeleton reorganization. Recent studies have shown that the activation of Rho family GTPases also induces collapse of the vimentin intermediate filament (IF) network in fibroblasts. Here, we report that Cdc42V12 induces the reorganization of vimentin IFs in Hela cells, and such reorganization is independent of actin and microtubule status. We analyzed the involvement of three serine/threonine kinase effectors, MRCK, PAK and p70 S6K in the Cdc42-induced vimentin reorganization. Surprisingly, the ROK-related MRCK is not involved in this IF reorganization. We detected phosphorylation of vimentin Ser72, a site phosphorylated by PAK, after Cdc42 activation. PAK inhibition partially blocked Cdc42-induced vimentin IF collapse suggesting the involvement of other effectors. We report that p70 S6 kinase (S6K)1 participates in this IF rearrangement since the inhibitor rapamycin or a dominant inhibitory S6K could reduce the Cdc42V12 or bradykinin-induced vimentin collapse. Further, inhibition of PAK and S6K in combination very effectively prevents Cdc42-induced vimentin IF collapse. Conversely, only in combination active PAK and S6K could induce a vimentin IF rearrangement that mimics the Cdc42 effect. Thus, Cdc42-induced vimentin reorganization involves PAK and, in a novel cytoskeletal role, p70 S6K.
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Affiliation(s)
- Wing Chan
- Glaxo-IMCB Group, Institute of Molecular and Cell Biology, Singapore, Singapore.
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Abstract
Mixed-lineage kinases (MLKs) are serine/threonine protein kinases that regulate signalling by the c-Jun amino-terminal kinase (JNK) and p38 mitogen-activated-protein kinase (MAPK) pathways. MLKs are represented in the genomes of both Caenorhabditis elegans and Drosophila melanogaster. The Drosophila MLK Slipper regulates JNK to control dorsal closure during embryonic morphogenesis. In mammalian cells, MLKs are implicated in the control of apoptosis and are potential drug targets for many neurodegenerative diseases.
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Affiliation(s)
- Kathleen A Gallo
- Department of Physiology, Michigan State University, East Lansing, Michigan 48824, USA.
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