51
|
Toker A. Achieving specificity in Akt signaling in cancer. Adv Biol Regul 2013; 52:78-87. [PMID: 21986444 DOI: 10.1016/j.advenzreg.2011.09.020] [Citation(s) in RCA: 57] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2011] [Accepted: 09/23/2011] [Indexed: 01/04/2023]
Affiliation(s)
- Alex Toker
- Department of Pathology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA 02215, USA.
| |
Collapse
|
52
|
Zhang H, Ghai P, Wu H, Wang C, Field J, Zhou GL. Mammalian adenylyl cyclase-associated protein 1 (CAP1) regulates cofilin function, the actin cytoskeleton, and cell adhesion. J Biol Chem 2013; 288:20966-20977. [PMID: 23737525 DOI: 10.1074/jbc.m113.484535] [Citation(s) in RCA: 69] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
CAP (adenylyl cyclase-associated protein) was first identified in yeast as a protein that regulates both the actin cytoskeleton and the Ras/cAMP pathway. Although the role in Ras signaling does not extend beyond yeast, evidence supports that CAP regulates the actin cytoskeleton in all eukaryotes including mammals. In vitro actin polymerization assays show that both mammalian and yeast CAP homologues facilitate cofilin-driven actin filament turnover. We generated HeLa cells with stable CAP1 knockdown using RNA interference. Depletion of CAP1 led to larger cell size and remarkably developed lamellipodia as well as accumulation of filamentous actin (F-actin). Moreover, we found that CAP1 depletion also led to changes in cofilin phosphorylation and localization as well as activation of focal adhesion kinase (FAK) and enhanced cell spreading. CAP1 forms complexes with the adhesion molecules FAK and Talin, which likely underlie the cell adhesion phenotypes through inside-out activation of integrin signaling. CAP1-depleted HeLa cells also had substantially elevated cell motility as well as invasion through Matrigel. In summary, in addition to generating in vitro and in vivo evidence further establishing the role of mammalian CAP1 in actin dynamics, we identified a novel cellular function for CAP1 in regulating cell adhesion.
Collapse
Affiliation(s)
- Haitao Zhang
- From the Department of Biological Sciences and; Molecular Biosciences Program, Arkansas State University, State University, Arkansas 72467
| | - Pooja Ghai
- From the Department of Biological Sciences and; Molecular Biosciences Program, Arkansas State University, State University, Arkansas 72467
| | - Huhehasi Wu
- From the Department of Biological Sciences and
| | - Changhui Wang
- the Shanghai Tenth People's Hospital of Tongji University, Shanghai 200072, China, and
| | - Jeffrey Field
- the Department of Pharmacology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104.
| | - Guo-Lei Zhou
- From the Department of Biological Sciences and; Molecular Biosciences Program, Arkansas State University, State University, Arkansas 72467,.
| |
Collapse
|
53
|
Kim JS, Sklarz T, Banks LB, Gohil M, Waickman AT, Skuli N, Krock BL, Luo CT, Hu W, Pollizzi KN, Li MO, Rathmell JC, Birnbaum MJ, Powell JD, Jordan MS, Koretzky GA. Natural and inducible TH17 cells are regulated differently by Akt and mTOR pathways. Nat Immunol 2013; 14:611-8. [PMID: 23644504 PMCID: PMC3711189 DOI: 10.1038/ni.2607] [Citation(s) in RCA: 64] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2013] [Accepted: 04/04/2013] [Indexed: 12/15/2022]
Abstract
Natural T helper 17 (nTH17) cells are a population of interleukin 17 (IL-17)-producing cells that acquire effector function in the thymus during development. Here we demonstrate that the serine/threonine kinase Akt has a critical role in regulating nTH17 cell development. Although Akt and the downstream mTORC1-ARNT-HIFα axis were required for generation of inducible TH17 (iTH17) cells, nTH17 cells developed independently of mTORC1. In contrast, mTORC2 and inhibition of Foxo proteins were critical for development of nTH17 cells. Moreover, distinct isoforms of Akt controlled the generation of TH17 cell subsets, as deletion of Akt2, but not of Akt1, led to defective generation of iTH17 cells. These findings define mechanisms regulating nTH17 cell development and reveal previously unknown roles of Akt and mTOR in shaping subsets of T cells.
Collapse
Affiliation(s)
- Jiyeon S Kim
- Abramson Family Cancer Research Institute, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
54
|
Haslinger P, Haider S, Sonderegger S, Otten JV, Pollheimer J, Whitley G, Knöfler M. AKT Isoforms 1 and 3 Regulate Basal and Epidermal Growth Factor-Stimulated SGHPL-5 Trophoblast Cell Migration in Humans1. Biol Reprod 2013; 88:54. [DOI: 10.1095/biolreprod.112.104778] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
|
55
|
|
56
|
Akt2 expression is associated with good long-term prognosis in oestrogen receptor positive breast cancer. Eur J Cancer 2013; 49:1196-204. [PMID: 23305873 DOI: 10.1016/j.ejca.2012.12.006] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2012] [Revised: 12/06/2012] [Accepted: 12/08/2012] [Indexed: 11/22/2022]
Abstract
INTRODUCTION Akt is a signalling modulator for many cellular processes, including metabolism, cell proliferation, cell survival and cell growth. Three isoforms of Akt have been identified, but only a few studies have concerned the isoform-specific roles in the prognosis of breast cancer patients. The aim of this study was to investigate the prognostic value of v-akt murine thymoma viral oncogene homologue 1 (Akt1) and v-akt murine thymoma viral oncogene homologue 2 (Akt2) in oestrogen receptor positive (ER+) and oestrogen receptor negative (ER-) breast cancer with long-term follow-up. MATERIAL AND METHODS The expression of Akt in tumour tissue was analysed with immunohistochemistry in a cohort of 272 postmenopausal patients with stage II breast cancer. The median follow-up time was 19 years. Hazard ratios (HRs) and 95% confidence intervals (CIs) were estimated using the Cox's proportional hazards model. RESULTS The risk of distant recurrence was reduced for patients with ER+ tumours expressing Akt2 compared to patients with no Akt2 expression (HR=0.49, 95% CI 0.29-0.82, p=0.007). When adjusting for important clinical tumour characteristics and treatment, Akt2 was still an independent prognostic factor (HR=0.38, 95% CI 0.21-0.68, p=0.001) and the association remained long-term. The prognostic value of Akt2 increased with higher oestrogen receptor levels from no effect among patients with ER- tumours to 68% risk reduction for the group with high ER-levels (P for trend=0.042). Akt1 showed no significant prognostic information. CONCLUSION Our results indicate that Akt2 expression is associated with a lower distant recurrence rate for patients with ER+ tumours and that this association remains long-term. The prognostic value of Akt2 increases with higher oestrogen receptor expression, motivating further mechanistic studies on the role of Akt2 in ER+ breast cancer.
Collapse
|
57
|
Higuchi M, Kihara R, Okazaki T, Aoki I, Suetsugu S, Gotoh Y. Akt1 promotes focal adhesion disassembly and cell motility through phosphorylation of FAK in growth factor-stimulated cells. J Cell Sci 2012; 126:745-55. [PMID: 23264741 DOI: 10.1242/jcs.112722] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
The crosstalk between spatial adhesion signals and temporal soluble signals is key in regulating cellular responses such as cell migration. Here we show that soluble growth factors enhance integrin signaling through Akt phosphorylation of FAK at Ser695 and Thr700. PDGF treatment or overexpression of active Akt1 in fibroblasts increased autophosphorylation of FAK at Tyr397, an essential event for integrin turnover and cell migration. Phosphorylation-defective mutants of FAK (S695A and T700A) underwent autophosphorylation at Tyr397 and promoted cell migration in response to the integrin ligand fibronectin, but importantly, not in response to PDGF. This study has unveiled a novel function of Akt as an 'ignition kinase' of FAK in growth factor signaling and may shed light on the mechanism by which growth factors regulate integrin signaling.
Collapse
Affiliation(s)
- Maiko Higuchi
- Institute of Molecular and Cellular Biosciences, University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-0032, Japan.
| | | | | | | | | | | |
Collapse
|
58
|
Gardner S, Anguiano M, Rotwein P. Defining Akt actions in muscle differentiation. Am J Physiol Cell Physiol 2012; 303:C1292-300. [PMID: 23076793 DOI: 10.1152/ajpcell.00259.2012] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Muscle development in childhood and muscle regeneration in adults are highly regulated processes that are necessary for reaching and maintaining optimal muscle mass and strength throughout life. Muscle repair after injury relies on stem cells, termed satellite cells, whose activity is controlled by complex signals mediated by cell-cell contact, by growth factors, and by hormones, which interact with genetic programs controlled by myogenic transcription factors. Insulin-like growth factors (IGFs) play key roles in muscle development and help coordinate muscle repair after injury, primarily by stimulating the phosphatidylinositol 3-kinase-Akt signaling pathway, and both in vitro and in vivo studies have shown that Akt kinase activity is critical for optimal muscle growth and regeneration. Here we find that of the two Akts expressed in muscle, Akt1 is essential for initiation of differentiation in culture and is required for normal myoblast motility, while Akt2 is dispensable. Although Akt2 deficiency did lead to diminished myotube maturation, as assessed by a decline in myofiber area and in fusion index, either Akt1 or Akt2 could restore these processes toward normal. Thus levels of Akt expression rather than distinct actions of individual Akt species are critical for normal myofiber development during the later stages of muscle differentiation.
Collapse
Affiliation(s)
- Samantha Gardner
- Department of Biochemistry and Molecular Biology, Oregon Health and Science University, Portland, OR 97239-3098, USA
| | | | | |
Collapse
|
59
|
Virtakoivu R, Pellinen T, Rantala JK, Perälä M, Ivaska J. Distinct roles of AKT isoforms in regulating β1-integrin activity, migration, and invasion in prostate cancer. Mol Biol Cell 2012; 23:3357-69. [PMID: 22809628 PMCID: PMC3431929 DOI: 10.1091/mbc.e12-03-0213] [Citation(s) in RCA: 62] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
On the basis of an RNA interference screen, we identify AKT1 and AKT2 as inhibitors of β1-integrin activity and invasion in prostate cancer. AKT1 siRNA induces β-integrin activity and up-regulation of RTKs known to function in cooperation with integrins. In contrast, AKT2 siRNA up-regulates microRNA-200, which increases integrin activity. AKT1 and AKT2 kinases have been shown to play opposite roles in breast cancer migration and invasion. In this study, an RNA interference screen for integrin activity inhibitors identified AKT1 as an inhibitor of β1-integrin activity in prostate cancer. Validation experiments investigating all three AKT isoforms demonstrated that, unlike in breast cancer, both AKT1 and AKT2 function as negative regulators of cell migration and invasion in PC3 prostate cancer cells. Down-regulation of AKT1 and AKT2, but not AKT3, induced activation of cell surface β1-integrins and enhanced adhesion, migration, and invasion. Silencing of AKT1 and AKT2 also resulted in increased focal adhesion size. Importantly, the mechanisms involved in integrin activity regulation were distinct for the two AKT isoforms. Silencing of AKT1 relieved feedback suppression of the expression and activity of several receptor tyrosine kinases, including EGFR and MET, with established cross-talk with β1-integrins. Silencing of AKT2, on the other hand, induced up-regulation of the microRNA-200 (miR-200) family, and overexpression of miR-200 was sufficient to induce integrin activity and cell migration in PC3 cells. Taken together, these data define an inhibitory role for both AKT1 and AKT2 in prostate cancer migration and invasion and highlight the cell type–specific actions of AKT kinases in the regulation of cell motility.
Collapse
|
60
|
Akt1 and Akt2 protein kinases differentially contribute to macrophage polarization. Proc Natl Acad Sci U S A 2012; 109:9517-22. [PMID: 22647600 DOI: 10.1073/pnas.1119038109] [Citation(s) in RCA: 424] [Impact Index Per Article: 35.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
Activated macrophages are described as classically activated or M1 type and alternatively activated or M2 type, depending on their response to proinflammatory stimuli and the expression of genetic markers including iNOS, arginase1, Ym1, and Fizz1. Here we report that Akt kinases differentially contribute to macrophage polarization, with Akt1 ablation giving rise to an M1 and Akt2 ablation resulting in an M2 phenotype. Accordingly, Akt2(-/-) mice were more resistant to LPS-induced endotoxin shock and to dextran sulfate sodium (DSS)-induced colitis than wild-type mice, whereas Akt1(-/-) mice were more sensitive. Cell depletion and reconstitution experiments in a DSS-induced colitis model confirmed that the effect was macrophage-dependent. Gene-silencing studies showed that the M2 phenotype of Akt2(-/-) macrophages was cell autonomous. The microRNA miR-155, whose expression was repressed in naive and in LPS-stimulated Akt2(-/-) macrophages, and its target C/EBPβ appear to play a key role in this process. C/EBPβ, a hallmark of M2 macrophages that regulates Arg1, was up-regulated upon Akt2 ablation or silencing. Overexpression or silencing of miR-155 confirmed its central role in Akt isoform-dependent M1/M2 polarization of macrophages.
Collapse
|
61
|
Woo DH, Yun SJ, Kim EK, Ha JM, Shin HK, Bae SS. Regulation of Skeletal Muscle Differentiation by Akt. ACTA ACUST UNITED AC 2012. [DOI: 10.5352/jls.2012.22.4.447] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
|
62
|
Bedoya FJ, Salguero-Aranda C, Cahuana GM, Tapia-Limonchi R, Soria B, Tejedo JR. Regulation of pancreatic β-cell survival by nitric oxide: clinical relevance. Islets 2012; 4:108-18. [PMID: 22614339 DOI: 10.4161/isl.19822] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
The reduction of pancreatic β-cell mass is an important factor in the development of type 1 and type 2 diabetes. Understanding the mechanisms that regulate the maintenance of pancreatic β-cell mass as well as β-cell death is necessary for the establishment of therapeutic strategies. In this context, nitric oxide (NO) is a diatomic, gaseous, highly reactive molecule with biological activity that participates in the regulation of pancreatic β-cell mass. Two types of cellular responses can be distinguished depending on the level of NO production. First, pancreatic β-cells exposed to inflammatory cytokines, lipid stress or hyperglycaemia produce high concentrations of NO, mainly due to the activation of inducible NO synthase (iNOS), thus promoting cell death. Meanwhile, under homeostatic conditions, low concentrations of NO, constitutively produced by endothelial NO synthase (eNOS), promote cell survival. Here, we will discuss the current knowledge of the NO-dependent mechanisms activated during cellular responses, emphasizing those related to the regulation of cell survival.
Collapse
Affiliation(s)
- Francisco J Bedoya
- Andalusian Center for Molecular Biology and Regenerative Medicine, University Pablo de Olavide, CIBERDEM, RED-TERCEL, Seville, Spain
| | | | | | | | | | | |
Collapse
|
63
|
Broussard JA, Lin WH, Majumdar D, Anderson B, Eason B, Brown CM, Webb DJ. The endosomal adaptor protein APPL1 impairs the turnover of leading edge adhesions to regulate cell migration. Mol Biol Cell 2012; 23:1486-99. [PMID: 22379109 PMCID: PMC3327316 DOI: 10.1091/mbc.e11-02-0124] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Cell migration is a complex process that requires the integration of signaling events that occur in distinct locations within the cell. Adaptor proteins, which can localize to different subcellular compartments, where they bring together key signaling proteins, are emerging as attractive candidates for controlling spatially coordinated processes. However, their function in regulating cell migration is not well understood. In this study, we demonstrate a novel role for the adaptor protein containing a pleckstrin-homology (PH) domain, phosphotyrosine-binding (PTB) domain, and leucine zipper motif 1 (APPL1) in regulating cell migration. APPL1 impairs migration by hindering the turnover of adhesions at the leading edge of cells. The mechanism by which APPL1 regulates migration and adhesion dynamics is by inhibiting the activity of the serine/threonine kinase Akt at the cell edge and within adhesions. In addition, APPL1 significantly decreases the tyrosine phosphorylation of Akt by the nonreceptor tyrosine kinase Src, which is critical for Akt-mediated cell migration. Thus, our results demonstrate an important new function for APPL1 in regulating cell migration and adhesion turnover through a mechanism that depends on Src and Akt. Moreover, our data further underscore the importance of adaptor proteins in modulating the flow of information through signaling pathways.
Collapse
Affiliation(s)
- Joshua A Broussard
- Department of Biological Sciences and Vanderbilt Kennedy Center for Research on Human Development, Nashville, TN 37235, USA
| | | | | | | | | | | | | |
Collapse
|
64
|
Beeson CC, Beeson GC, Buff H, Eldridge J, Zhang A, Seth A, Demcheva M, Vournakis JN, Muise-Helmericks RC. Integrin-dependent Akt1 activation regulates PGC-1 expression and fatty acid oxidation. J Vasc Res 2012; 49:89-100. [PMID: 22249024 DOI: 10.1159/000332326] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2011] [Accepted: 08/17/2011] [Indexed: 02/01/2023] Open
Abstract
BACKGROUND Poly-N-acetyl glucosamine nanofibers derived from a marine diatom have been used to increase cutaneous wound healing. These nanofibers exert their activity by specifically activating integrins, which makes them a useful tool for dissecting integrin-mediated pathways. We have shown that short-fiber poly-N-acetyl glucosamine nanofiber (sNAG) treatment of endothelial cells results in increased cell motility and metabolic rate in the absence of increased cell proliferation. RESULTS Using a Seahorse Bioanalyzer to measure oxygen consumption in real time, we show that sNAG treatment increases oxygen consumption rates, correlated with an integrin-dependent activation of Akt1. Akt1 activation leads to an increase in the expression of the transcriptional coactivator, peroxisome proliferator-activated receptor γ coactivator-1α (PGC-1α). This is not due to increased mitochondrial biogenesis, but is associated with an increase in the expression of pyruvate dehydrogenase kinase 4 (PDK4), suggesting regulation of fatty acid oxidation. Blockade of fatty acid oxidation with etomoxir, an O-carnitine palmitoyltransferase-1 inhibitor, blocks the sNAG-dependent increased oxygen consumption. (3)H-palmitate uptake experiments indicate a PDK4-dependent increase in fatty acid oxidation, which is required for nanofiber-induced cell motility. CONCLUSIONS Our findings imply a linear pathway whereby an integrin-dependent activation of Akt1 leads to increased PGC-1α and PDK4 expression resulting in increased energy production by fatty acid oxidation.
Collapse
Affiliation(s)
- Craig C Beeson
- Department of Regenerative Medicine and Cell Biology, Medical University of South Carolina, Charleston, S.C., USA
| | | | | | | | | | | | | | | | | |
Collapse
|
65
|
Martin VA, Wang WH, Lipchik AM, Parker LL, He Y, Zhang S, Zhang ZY, Geahlen RL. Akt2 inhibits the activation of NFAT in lymphocytes by modulating calcium release from intracellular stores. Cell Signal 2012; 24:1064-73. [PMID: 22261254 DOI: 10.1016/j.cellsig.2012.01.001] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2011] [Revised: 12/20/2011] [Accepted: 01/04/2012] [Indexed: 12/22/2022]
Abstract
The engagement of antigen receptors on lymphocytes leads to the activation of phospholipase C-γ, the mobilization of intracellular calcium and the activation of the NFAT transcription factor. The coupling of antigen receptors to the activation of NFAT is modulated by numerous cellular effectors including phospho-inositide 3-kinase (PI3K), which is activated following receptor cross-linking. The activation of PI3K has both positive and negative effects on the receptor-mediated activation of NFAT. An increase in the level and activity of Akt2, a target of activated PI3K, potently inhibits the subsequent activation of NFAT. In contrast, an elevation in Akt1 has no effect on signaling. Signaling pathways operating both upstream and downstream of inositol 1,4,5-trisphosphate (IP3)-stimulated calcium release from intracellular stores are unaffected by Akt2. An increase in the level of Akt2 has no significant effect on the initial amplitude, but substantially reduces the duration of calcium mobilization. The ability of Akt2 to inhibit prolonged calcium mobilization is abrogated by the administration of a cell permeable peptide that blocks the interaction between Bcl-2 and the IP3 receptor. Thus, Akt2 is a negative regulator of NFAT activation through its ability to inhibit calcium mobilization from the ER.
Collapse
Affiliation(s)
- Victoria A Martin
- Department of Medicinal Chemistry and Molecular Pharmacology and Purdue Center for Cancer Research, Purdue University, West Lafayette, IN, USA
| | | | | | | | | | | | | | | |
Collapse
|
66
|
Selective signaling by Akt1 controls osteoblast differentiation and osteoblast-mediated osteoclast development. Mol Cell Biol 2011; 32:490-500. [PMID: 22064480 DOI: 10.1128/mcb.06361-11] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
Maintaining optimal bone integrity, mass, and strength throughout adult life requires ongoing bone remodeling, which involves coordinated activity between actions of bone-resorbing osteoclasts and bone forming-osteoblasts. Osteoporosis is a disorder of remodeling in which bone resorption outstrips deposition, leading to diminished bone mass and an increased risk of fractures. Here we identify Akt1 as a unique signaling intermediate in osteoblasts that can control both osteoblast and osteoclast differentiation. Targeted knockdown of Akt1 in mouse primary bone marrow stromal cells or in a mesenchymal stem cell line or genetic knockout of Akt1 stimulated osteoblast differentiation secondary to increased expression of the osteogenic transcription factor Runx2. Despite enhanced osteoblast differentiation, coupled osteoclastogenesis in Akt1 deficiency was markedly inhibited, with reduced accumulation of specific osteoclast mRNAs and proteins and impaired fusion to form multinucleated osteoclasts, defects secondary to diminished production of receptor activator of NF-κB ligand (RANKL) and macrophage colony-stimulating factor (m-CSF), critical osteoblast-derived osteoclast differentiation factors. Delivery of recombinant lentiviruses encoding Akt1 but not Akt2 to Akt1-deficient osteoblast progenitors reversed the increased osteoblast differentiation and, by boosting accumulation of RANKL and m-CSF, restored normal osteoclastogenesis, as did the addition of recombinant RANKL to conditioned culture medium from Akt1-deficient osteoblasts. Our results support the idea that targeted inhibition of Akt1 could lead to therapeutically useful net bone acquisition, and they indicate that closely related Akt1 and Akt2 exert distinct effects on cellular differentiation pathways.
Collapse
|
67
|
Huang Q, Lan F, Zheng Z, Xie F, Han J, Dong L, Xie Y, Zheng F. Akt2 kinase suppresses glyceraldehyde-3-phosphate dehydrogenase (GAPDH)-mediated apoptosis in ovarian cancer cells via phosphorylating GAPDH at threonine 237 and decreasing its nuclear translocation. J Biol Chem 2011; 286:42211-42220. [PMID: 21979951 DOI: 10.1074/jbc.m111.296905] [Citation(s) in RCA: 73] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Protein kinase B (Akt) plays important roles in regulation of cell growth and survival, but while many aspects of its mechanism of action are known, there are potentially additional regulatory events that remain to be discovered. Here we detected a 36-kDa protein that was co-immunoprecipitated with protein kinase Bβ (Akt2) in OVCAR-3 ovarian cancer cells. The protein was identified to be glyceraldehyde-3-phosphate dehydrogenase (GAPDH) by MALDI-TOF/TOF MS, and the interaction of Akt2 and GAPDH was verified by reverse immunoprecipitation. Our further study showed that Akt2 may suppress GAPDH-mediated apoptosis in ovarian cancer cells. Overexpression of GAPDH increased ovarian cancer cell apoptosis induced by H(2)O(2), which was inhibited by Akt2 overexpression and restored by the PI3K/Akt inhibitor wortmannin or Akt2 siRNA. Akt2 phosphorylated Thr-237 of GAPDH and decreased its nuclear translocation, an essential step for GAPDH-mediated apoptosis. The interaction between Akt2 and GAPDH may be important in ovarian cancer as immunohistochemical analysis of 10 normal and 30 cancerous ovarian tissues revealed that decreased nuclear expression of GAPDH correlated with activation (phosphorylation) of Akt2. In conclusion, our study suggests that activated Akt2 may increase ovarian cancer cell survival via inhibition of GAPDH-induced apoptosis. This effect of Akt2 is partly mediated by its phosphorylation of GAPDH at Thr-237, which results in the inhibition of GAPDH nuclear translocation.
Collapse
Affiliation(s)
- Qiaojia Huang
- Department of Experimental Medicine, Fuzhou General Hospital (Dongfang Hospital), 156 North Xi-er Huan Road, Fuzhou City, Fujian Province 350025, China.
| | - Fenghua Lan
- Department of Experimental Medicine, Fuzhou General Hospital (Dongfang Hospital), 156 North Xi-er Huan Road, Fuzhou City, Fujian Province 350025, China
| | - Zhiyong Zheng
- Department of Pathology, Fuzhou General Hospital (Dongfang Hospital), 156 North Xi-er Huan Road, Fuzhou City, Fujian Province 350025, China
| | - Feilai Xie
- Department of Pathology, Fuzhou General Hospital (Dongfang Hospital), 156 North Xi-er Huan Road, Fuzhou City, Fujian Province 350025, China
| | - Junyong Han
- Department of Experimental Medicine, Fuzhou General Hospital (Dongfang Hospital), 156 North Xi-er Huan Road, Fuzhou City, Fujian Province 350025, China
| | - Lihong Dong
- Department of Experimental Medicine, Fuzhou General Hospital (Dongfang Hospital), 156 North Xi-er Huan Road, Fuzhou City, Fujian Province 350025, China
| | - Yanchuan Xie
- Department of Experimental Medicine, Fuzhou General Hospital (Dongfang Hospital), 156 North Xi-er Huan Road, Fuzhou City, Fujian Province 350025, China
| | - Feng Zheng
- Department of Nephrology, Fuzhou General Hospital (Dongfang Hospital), 156 North Xi-er Huan Road, Fuzhou City, Fujian Province 350025, China
| |
Collapse
|
68
|
Lee MW, Kim DS, Lee JH, Lee BS, Lee SH, Jung HL, Sung KW, Kim HT, Yoo KH, Koo HH. Roles of AKT1 and AKT2 in non-small cell lung cancer cell survival, growth, and migration. Cancer Sci 2011; 102:1822-8. [PMID: 21722267 PMCID: PMC11158224 DOI: 10.1111/j.1349-7006.2011.02025.x] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
Abstract
Although AKT ⁄ protein kinase B is constitutively active in nonsmall cell lung cancer (NSCLC) cells and is an attractive target for enhancing the cytotoxicity of therapeutic agents, the distinct roles of the AKT isoforms in NSCLC are largely unknown. In the present study, we investigated the roles of AKT1 and AKT2 in NSCLC cells using RNAi. The siRNA targeting of AKT1 or AKT2 effectively decreased protein levels of AKT1 and AKT2, respectively, in A549 and H460 cells. Cisplatin treatment of these cells increased apoptotic cell death compared with control. The siRNA-induced knockdown of AKT1 in H460 cells significantly decreased basal MEK⁄ ERK1 ⁄ 2 activity, resulting in nuclear factor-κB activation, whereas knockdown of AKT2 resulted in anti-apoptotic Bcl-2 family protein MCL-1 (MCL-1) cleavage, the collapse of mitochondrial membrane potential, cytochrome c release, and activation of the caspase cascade. Consequently, both siRNA treatments enhanced the chemosensitivity of H460 cells to cisplatin. However, neither AKT1 nor AKT2 siRNA treatment had any effect of p27 expression, and although both treatments tended to induced G₂ ⁄M phase arrest, the effect was not statistically significant. Treatment with AKT1 siRNA markedly decreased colony formation growth and migration, but AKT2 siRNA had no significant effects on these parameters. These data suggest that AKT1 and AKT2 both contribute to cell survival, albeit via different mechanisms, and that the effects on cell growth and migration are predominantly regulated by AKT1. These findings may aid in refining targeted strategies for the inhibition of AKT isoforms towards the sensitization of NSCLC cells to therapeutic agents.
Collapse
Affiliation(s)
- Myoung W Lee
- Department of Pediatrics, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea
| | | | | | | | | | | | | | | | | | | |
Collapse
|
69
|
Wani R, Bharathi NS, Field J, Tsang AW, Furdui CM. Oxidation of Akt2 kinase promotes cell migration and regulates G1-S transition in the cell cycle. Cell Cycle 2011; 10:3263-8. [PMID: 21957489 DOI: 10.4161/cc.10.19.17738] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Phosphorylation has long been recognized as the key mediator of protein signaling. New modes of signaling regulation are emerging with the development of specific chemical probes and application of high-throughput mass spectrometry technologies. Using biotin-tagged chemical probes for protein oxidation, mass spectrometry and functional assays, our group has recently reported isoform-specific oxidation of Akt2 in response to PDGF signaling. The studies included here investigate the functional consequence of oxidation on Akt2-mediated cell migration and cell cycle. Akt2-KO MEFs transduced with WT and Cys124Ser Akt2 were used as the model system for these studies. The implications of these findings on disease pathology are discussed.
Collapse
Affiliation(s)
- Revati Wani
- Section on Molecular Medicine, Department of Internal Medicine, Wake Forest School of Medicine, Winston-Salem, NC, USA
| | | | | | | | | |
Collapse
|
70
|
Rahman P, Huysmans RD, Wiradjaja F, Gurung R, Ooms LM, Sheffield DA, Dyson JM, Layton MJ, Sriratana A, Takada H, Tiganis T, Mitchell CA. Silencer of death domains (SODD) inhibits skeletal muscle and kidney enriched inositol 5-phosphatase (SKIP) and regulates phosphoinositide 3-kinase (PI3K)/Akt signaling to the actin cytoskeleton. J Biol Chem 2011; 286:29758-70. [PMID: 21712384 DOI: 10.1074/jbc.m111.263103] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
Phosphoinositide 3-kinase (PI3K) regulates cell polarity and migration by generating phosphatidylinositol 3,4,5-trisphosphate (PI(3,4,5)P(3)) at the leading edge of migrating cells. The serine-threonine protein kinase Akt binds to PI(3,4,5)P(3), resulting in its activation. Active Akt promotes spatially regulated actin cytoskeletal remodeling and thereby directed cell migration. The inositol polyphosphate 5-phosphatases (5-ptases) degrade PI(3,4,5)P(3) to form PI(3,4)P(2), which leads to diminished Akt activation. Several 5-ptases, including SKIP and SHIP2, inhibit actin cytoskeletal reorganization by opposing PI3K/Akt signaling. In this current study, we identify a molecular co-chaperone termed silencer of death domains (SODD/BAG4) that forms a complex with several 5-ptase family members, including SKIP, SHIP1, and SHIP2. The interaction between SODD and SKIP exerts an inhibitory effect on SKIP PI(3,4,5)P(3) 5-ptase catalytic activity and consequently enhances the recruitment of PI(3,4,5)P(3)-effectors to the plasma membrane. In contrast, SODD(-/-) mouse embryonic fibroblasts exhibit reduced Akt-Ser(473) and -Thr(308) phosphorylation following EGF stimulation, associated with increased SKIP PI(3,4,5)P(3)-5-ptase activity. SODD(-/-) mouse embryonic fibroblasts exhibit decreased EGF-stimulated F-actin stress fibers, lamellipodia, and focal adhesion complexity, a phenotype that is rescued by the expression of constitutively active Akt1. Furthermore, reduced cell migration was observed in SODD(-/-) macrophages, which express the three 5-ptases shown to interact with SODD (SKIP, SHIP1, and SHIP2). Therefore, this study identifies SODD as a novel regulator of PI3K/Akt signaling to the actin cytoskeleton.
Collapse
Affiliation(s)
- Parvin Rahman
- Department of Biochemistry and Molecular Biology, Monash University, Clayton, Victoria, Australia
| | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
71
|
Isoform-specific regulation of Akt by PDGF-induced reactive oxygen species. Proc Natl Acad Sci U S A 2011; 108:10550-5. [PMID: 21670275 DOI: 10.1073/pnas.1011665108] [Citation(s) in RCA: 105] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Isoform-specific signaling of Akt, a major signaling hub and a prominent therapeutic target, remained poorly defined until recently. Subcellular distribution, tissue-specific expression, substrate specificity, and posttranslational modifications are believed to underlie isoform-specific signaling of Akt. The studies reported here show inhibition of Akt2 activity under physiologically relevant conditions of oxidation created by PDGF-induced reactive oxygen species. Combined MS and functional assays identified Cys124 located in the linker region between the N-terminal pleckstrin homology domain and the catalytic kinase domain as one of the unique regulatory redox sites in Akt2 with functional consequence on PDGF-stimulated glucose uptake. A model is proposed describing the consequence of increased endogenous oxidation induced by extracellular cues such as PDGF on Akt2 activity.
Collapse
|
72
|
Adams JR, Schachter NF, Liu JC, Zacksenhaus E, Egan SE. Elevated PI3K signaling drives multiple breast cancer subtypes. Oncotarget 2011; 2:435-47. [PMID: 21646685 PMCID: PMC3248195 DOI: 10.18632/oncotarget.285] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
Most human breast tumors have mutations that elevate signaling through a key metabolic pathway that is induced by insulin and a number of growth factors. This pathway serves to activate an enzyme known as phosphatidylinositol 3' kinase (PI3K) as well as to regulate proteins that signal in response to lipid products of PI3K. The specific mutations that activate this pathway in breast cancer can occur in genes coding for tyrosine kinase receptors, adaptor proteins linked to PI3K, catalytic and regulatory subunits of PI3K, serine/threonine kinases that function downstream of PI3K, and also phosphatidylinositol 3' phosphatase tumor suppressors that function to antagonize this pathway. While each genetic change results in net elevation of PI3K pathway signaling, and all major breast cancer subtypes show pathway activation, the specific mutation(s) involved in any one tumor may play an important role in defining tumor subtype, prognosis and even sensitivity to therapy. Here, we describe mouse models of breast cancer with elevated PI3K signaling, and how they may be used to guide development of novel therapeutics.
Collapse
Affiliation(s)
- Jessica R. Adams
- 1 Program in Developmental and Stem Cell Biology, The Hospital for Sick Children, 101 College St., East Tower
- 2 The Department of Molecular Genetics, University of Toronto, Toronto, Ontario, Canada
| | - Nathan F. Schachter
- 1 Program in Developmental and Stem Cell Biology, The Hospital for Sick Children, 101 College St., East Tower
- 2 The Department of Molecular Genetics, University of Toronto, Toronto, Ontario, Canada
| | - Jeff C. Liu
- 3 Division of Cell and Molecular Biology, Toronto General Research Institute–University Health Network, Toronto, Ontario, Canada
| | - Eldad Zacksenhaus
- 3 Division of Cell and Molecular Biology, Toronto General Research Institute–University Health Network, Toronto, Ontario, Canada
- 4 The Department of Medical Biophysics, University of Toronto, Toronto, Ontario, Canada
| | - Sean E. Egan
- 1 Program in Developmental and Stem Cell Biology, The Hospital for Sick Children, 101 College St., East Tower
- 2 The Department of Molecular Genetics, University of Toronto, Toronto, Ontario, Canada
| |
Collapse
|
73
|
Akt1 deficiency delays tumor progression, vascular invasion, and distant metastasis in a murine model of thyroid cancer. Oncogene 2011; 30:4307-15. [PMID: 21532616 PMCID: PMC3151477 DOI: 10.1038/onc.2011.136] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Akt activation is common in progressive thyroid cancer. In breast cancer, Akt1 induced primary cancer growth, but is reported to inhibit metastasis in vivo in several model systems. In contrast, clinical and in vitro studies suggest a metastasis-promoting role for Akt1 in thyroid cancer. The goal of this study was to determine the functional role of Akt1 in thyroid cancer growth and metastatic progression in vivo using thyroid hormone receptor βPV/PV knock-in (PV) mice which develop metastatic thyroid cancer. We crossed Akt1-/- and PV mice and compared tumor development, local progression, metastasis, and histology in TRβPV/PV/Akt1+/+ (PVPV-Akt1WT) and TRβPV/PV/Akt1-/- (PVPV-Akt1KO) mice. Mice were sacrificed at 3, 6, 9, 12, and 15 months; necropsy was performed and serum TSH was measured. Thyroid hyperplasia occurred in both groups beginning at three months; the thyroid size was greater in the PVPV-Akt1WT mice (p<0.001). In comparison with PVPV-Akt1WT mice, thyroid cancer development was delayed in the PVPV-Akt1KO mice (P=0.003) and the degree of tumor invasion was reduced. The PVPV-Akt1WT mice displayed pulmonary metastases at 12 and 15 months of age, by contrast PVPV-Akt1KO mice did not develop distant metastases at 15 months of age. Despite continued expression of Akt2 or Akt3, pAkt levels were decreased, and there was evidence of reduced Akt effect on p27 in the PVPV-Akt1KO thyroids. TSH levels were similarly elevated in PV mice regardless of Akt1 expression. In conclusion, thyroid cancer development and progression in TRβPV/PV mice are Akt1-dependent, consistent with a tumor progression-promoting role in this murine thyroid cancer model.
Collapse
|
74
|
Kim EK, Yun SJ, Ha JM, Kim YW, Jin IH, Yun J, Shin HK, Song SH, Kim JH, Lee JS, Kim CD, Bae SS. Selective activation of Akt1 by mammalian target of rapamycin complex 2 regulates cancer cell migration, invasion, and metastasis. Oncogene 2011; 30:2954-63. [PMID: 21339740 DOI: 10.1038/onc.2011.22] [Citation(s) in RCA: 94] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Mammalian target of rapamycin complex (mTORC) regulates a variety of cellular responses including proliferation, growth, differentiation and cell migration. In this study, we show that mammalian target of rapamycin complex 2 (mTORC2) regulates invasive cancer cell migration through selective activation of Akt1. Insulin-like growth factor-1 (IGF-1)-induced SKOV-3 cell migration was completely abolished by phosphatidylinositol 3-kinase (PI3K) (LY294002, 10 μM) or Akt inhibitors (SH-5, 50 μM), whereas inhibition of extracellular-regulated kinase by an ERK inhibitor (PD98059, 10 μM) or inhibition of mammalian target of rapamycin complex 1 (mTORC1) by an mTORC1 inhibitor (Rapamycin, 100 nM) did not affect IGF-1-induced SKOV-3 cell migration. Inactivation of mTORC2 by silencing Rapamycin-insensitive companion of mTOR (Rictor), abolished IGF-1-induced SKOV-3 cell migration as well as activation of Akt. However, inactivation of mTORC1 by silencing of Raptor had no effect. Silencing of Akt1 but not Akt2 attenuated IGF-1-induced SKOV-3 cell migration. Rictor was preferentially associated with Akt1 rather than Akt2, and over-expression of Rictor facilitated IGF-1-induced Akt1 activation. Expression of PIP3-dependent Rac exchanger1 (P-Rex1), a Rac guanosine exchange factor and a component of the mTOR complex, strongly stimulated activation of Akt1. Furthermore, knockdown of P-Rex1 attenuated Akt activation as well as IGF-1-induced SKOV-3 cell migration. Silencing of Akt1 or P-Rex1 abolished IGF-1-induced SKOV-3 cell invasion. Finally, silencing of Akt1 blocked in vivo metastasis, whereas silencing of Akt2 did not. Given these results, we suggest that selective activation of Akt1 through mTORC2 and P-Rex1 regulates cancer cell migration, invasion and metastasis.
Collapse
Affiliation(s)
- E K Kim
- MRC for Ischemic Tissue Regeneration and Medical Research Institute, Department of Pharmacology, Pusan National University School of Medicine,Yangsan-si, Republic of Korea
| | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
75
|
Wang H, Brown J, Garcia CA, Tang Y, Benakanakere MR, Greenway T, Alard P, Kinane DF, Martin M. The role of glycogen synthase kinase 3 in regulating IFN-β-mediated IL-10 production. THE JOURNAL OF IMMUNOLOGY 2010; 186:675-84. [PMID: 21160051 DOI: 10.4049/jimmunol.1001473] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
The ability of IFN-β to induce IL-10 production from innate immune cells is important for its anti-inflammatory properties and is believed to contribute to its therapeutic value in treating multiple sclerosis patients. In this study, we identified that IFN-β stimulates IL-10 production by activating the JAK1- and PI3K-signaling pathways. JAK1 activity was required for IFN-β to activate PI3K and Akt1 that resulted in repression of glycogen synthase kinase 3 (GSK3)-β activity. IFN-β-mediated suppression of GSK3-β promoted IL-10, because IL-10 production by IFN-β-stimulated dendritic cells (DC) expressing an active GSK3-β knockin was severely reduced, whereas pharmacological or genetic inhibition of GSK3-β augmented IL-10 production. IFN-β increased the phosphorylated levels of CREB and STAT3 but only CREB levels were affected by PI3K. Also, a knockdown in CREB, but not STAT3, affected the capacity of IFN-β to induce IL-10 from DC. IL-10 production by IFN-β-stimulated DC was shown to suppress IFN-γ and IL-17 production by myelin oligodendrocyte glycoprotein-specific CD4(+) T cells, and this IL-10-dependent anti-inflammatory effect was enhanced by directly targeting GSK3 in DC. These findings highlight how IFN-β induces IL-10 production and the importance that IL-10 plays in its anti-inflammatory properties, as well as identify a therapeutic target that could be used to increase the IL-10-dependent anti-inflammatory properties of IFN-β.
Collapse
Affiliation(s)
- Huizhi Wang
- Department of Microbiology and Immunology, University of Louisville School of Medicine, Louisville, KY 40202, USA
| | | | | | | | | | | | | | | | | |
Collapse
|
76
|
Phosphoinositides are essential coactivators for p21-activated kinase 1. Mol Cell 2010; 40:493-500. [PMID: 21070974 DOI: 10.1016/j.molcel.2010.10.015] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2010] [Revised: 06/25/2010] [Accepted: 08/25/2010] [Indexed: 11/24/2022]
Abstract
Phospholipid-enriched membranes such as the plasma membrane can serve as direct regulators of kinase signaling. Pak1 is involved in growth factor signaling at the plasma membrane, and its dysregulation is implicated in cancer. Pak1 adopts an autoinhibited conformation that is relieved upon binding to membrane-bound Rho GTPases Rac1 or Cdc42, but whether lipids also regulate Pak1 in vivo is unknown. We show here that phosphoinositides, particularly PIP(2), potentiate Rho-GTPase-mediated Pak1 activity. A positively charged region of Pak1 binds to phosphoinositide-containing membranes, and this interaction is essential for membrane recruitment and activation of Pak1 in response to extracellular signals. Our results highlight an active role for lipids as allosteric regulators of Pak1 and suggest that Pak1 is a "coincidence detector" whose activation depends on GTPases present in phosphoinositide-rich membranes. These findings expand the role of phosphoinositides in kinase signaling and suggest how altered phosphoinositide metabolism may upregulate Pak1 activity in cancer cells.
Collapse
|
77
|
Kichina JV, Goc A, Al-Husein B, Somanath PR, Kandel ES. PAK1 as a therapeutic target. Expert Opin Ther Targets 2010; 14:703-25. [PMID: 20507214 DOI: 10.1517/14728222.2010.492779] [Citation(s) in RCA: 94] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
IMPORTANCE OF THE FIELD P21-activated kinases (PAKs) are involved in multiple signal transduction pathways in mammalian cells. PAKs, and PAK1 in particular, play a role in such disorders as cancer, mental retardation and allergy. Cell motility, survival and proliferation, the organization and function of cytoskeleton and extracellular matrix, transcription and translation are among the processes affected by PAK1. AREAS COVERED IN THIS REVIEW We discuss the mechanisms that control PAK1 activity, its involvement in physiological and pathophysiological processes, the benefits and the drawbacks of the current tools to regulate PAK1 activity, the evidence that suggests PAK1 as a therapeutic target and the likely directions of future research. WHAT THE READER WILL GAIN The reader will gain a better knowledge and understanding of the areas described above. TAKE HOME MESSAGE PAK1 is a promising therapeutic target in cancer and allergen-induced disorders. Its suitability as a target in vascular, neurological and infectious diseases remains ambiguous. Further advancement of this field requires progress on such issues as the development of specific and clinically acceptable inhibitors, the choice between targeting one or multiple PAK isoforms, elucidation of the individual roles of PAK1 targets and the mechanisms that may circumvent inhibition of PAK1.
Collapse
Affiliation(s)
- Julia V Kichina
- Roswell Park Cancer Institute, Department of Cell Stress Biology, Elm and Carlton Streets, Buffalo, NY 14263, USA
| | | | | | | | | |
Collapse
|
78
|
Ellis IR, Jones SJ, Lindsay Y, Ohe G, Schor AM, Schor SL, Leslie NR. Migration Stimulating Factor (MSF) promotes fibroblast migration by inhibiting AKT. Cell Signal 2010; 22:1655-9. [PMID: 20600851 DOI: 10.1016/j.cellsig.2010.06.005] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2010] [Revised: 06/15/2010] [Accepted: 06/21/2010] [Indexed: 11/16/2022]
Abstract
The protein kinase AKT is activated strongly by many motogenic growth factors, yet has recently been shown capable of inhibiting migration in several cell types. Here we report that treatment with Migration Stimulating Factor (MSF), a truncated form of fibronectin that promotes the migration of many cell types, inhibits AKT activity in human fibroblasts and endothelial cells. In fibroblasts, treatment with either MSF or the AKT inhibitor, Akti-1/2, stimulated migration into 3D collagen gels to a similar extent and the effects of Akti-1/2 on migration could be blocked by the expression of an inhibitor-resistant mutant, AKT1 W80A. These data indicate that MSF promotes fibroblast migration, at least in part, by inhibiting the activity of AKT.
Collapse
Affiliation(s)
- Ian R Ellis
- Unit of Cell and Molecular Biology, The Dental School, College of Medicine, Dentistry and Nursing, University of Dundee, Park Place, Dundee DD1 4HR, UK
| | | | | | | | | | | | | |
Collapse
|
79
|
The actin-bundling protein palladin is an Akt1-specific substrate that regulates breast cancer cell migration. Mol Cell 2010; 38:333-44. [PMID: 20471940 DOI: 10.1016/j.molcel.2010.02.031] [Citation(s) in RCA: 136] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2009] [Revised: 01/15/2010] [Accepted: 02/05/2010] [Indexed: 11/22/2022]
Abstract
The phosphatidylinositol 3-kinase (PI3K) signaling pathway is frequently deregulated in cancer. Downstream of PI3K, Akt1 and Akt2 have opposing roles in breast cancer invasive migration, leading to metastatic dissemination. Here, we identify palladin, an actin-associated protein, as an Akt1-specific substrate that modulates breast cancer cell invasive migration. Akt1, but not Akt2, phosphorylates palladin at Ser507 in a domain that is critical for F-actin bundling. Downregulation of palladin enhances migration and invasion of breast cancer cells and induces abnormal branching morphogenesis in 3D cultures. Palladin phosphorylation at Ser507 is required for Akt1-mediated inhibition of breast cancer cell migration and also for F-actin bundling, leading to the maintenance of an organized actin cytoskeleton. These findings identify palladin as an Akt1-specific substrate that regulates cell motility and provide a molecular mechanism that accounts for the functional distinction between Akt isoforms in breast cancer cell signaling to cell migration.
Collapse
|
80
|
Saji M, Ringel MD. The PI3K-Akt-mTOR pathway in initiation and progression of thyroid tumors. Mol Cell Endocrinol 2010; 321:20-8. [PMID: 19897009 PMCID: PMC2849843 DOI: 10.1016/j.mce.2009.10.016] [Citation(s) in RCA: 132] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/07/2009] [Revised: 10/22/2009] [Accepted: 10/23/2009] [Indexed: 02/07/2023]
Abstract
The phosphoinositide-3 (OH) kinase (PI3K) signaling cascade is involved in regulating glucose uptake and metabolism, growth, motility, and other essential functions for cell survival. Unregulated activation of this pathway commonly occurs in cancer through a variety of mechanisms, including genetic mutations of kinases and regulatory proteins, epigenetic alterations that alter gene expression and translation, and posttranslational modifications. In thyroid cancer, constitutive activation of PI3K signaling has been shown to play a role in the genetic predisposition for thyroid neoplasia in Cowden's syndrome, and is recognized to be frequently overactivated in sporadic forms of thyroid cancer including those with aggressive clinical behaviors. In this review, the key signaling molecules in the PI3K signaling cascade, the abnormalities known to occur in thyroid cancer, and the potential for therapeutic targeting of PI3K pathway members will be discussed.
Collapse
Affiliation(s)
- Motoyasu Saji
- Division of Endocrinology, Diabetes and Metabolism, The Ohio State University Medical Center, The Ohio State University and The Arthur G. James Cancer Hospital and Richard J. Solove Research Institute, The Ohio State University, Columbus, Ohio, USA
| | - Matthew D. Ringel
- Division of Endocrinology, Diabetes and Metabolism, The Ohio State University Medical Center, The Ohio State University and The Arthur G. James Cancer Hospital and Richard J. Solove Research Institute, The Ohio State University, Columbus, Ohio, USA
- Division of Oncology, The Ohio State University Medical Center, The Ohio State University and The Arthur G. James Cancer Hospital and Richard J. Solove Research Institute, The Ohio State University, Columbus, Ohio, USA
- Department of Internal Medicine & Molecular Virology, Immunology and Genetics, The Ohio State University Medical Center, The Ohio State University and The Arthur G. James Cancer Hospital and Richard J. Solove Research Institute, The Ohio State University, Columbus, Ohio, USA
| |
Collapse
|
81
|
Dillon RL, Muller WJ. Distinct biological roles for the akt family in mammary tumor progression. Cancer Res 2010; 70:4260-4. [PMID: 20424120 DOI: 10.1158/0008-5472.can-10-0266] [Citation(s) in RCA: 128] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The phosphatidylinositol 3' kinase/Akt pathway is frequently dysregulated in cancer, which can have unfavorable consequences in terms of cell proliferation, survival, metabolism, and migration. Increasing evidence suggests that Akt1, Akt2, and Akt3 play unique roles in breast cancer initiation and progression. We have recently shown that in contrast to Akt1, which accelerates mammary tumor induction in transgenic mice, Akt2 promotes metastasis of tumor cells without affecting the latency of tumor development. Despite the distinct phenotypic outputs resulting from Akt1 or Akt2 activation, very little is known about the mode by which such unique functions originate from these highly related kinases. Here we discuss potential mechanisms contributing to the differing functional specificity of Akt1 and Akt2 with respect to migration, invasion, and metastasis.
Collapse
Affiliation(s)
- Rachelle L Dillon
- Manitoba Institute of Cell Biology, University of Manitoba, Winnipeg, Manitoba, Canada
| | | |
Collapse
|
82
|
van Dijk M, van Bezu J, van Abel D, Dunk C, Blankenstein MA, Oudejans CBM, Lye SJ. The STOX1 genotype associated with pre-eclampsia leads to a reduction of trophoblast invasion by alpha-T-catenin upregulation. Hum Mol Genet 2010; 19:2658-67. [PMID: 20400461 DOI: 10.1093/hmg/ddq152] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
By using complementary in vitro and ex vivo approaches, we show that the risk allele (Y153H) of the pre-eclampsia susceptibility gene STOX1 negatively regulates trophoblast invasion by upregulation of the cell-cell adhesion protein alpha-T-catenin (CTNNA3). This is effectuated at the crucial epithelial-mesenchymal transition of proliferative into invasive extravillous trophoblast. This STOX1-CTNNA3 interaction is direct and includes Akt-mediated phosphorylated control of nucleo-cytoplasmic shuttling and ubiquitin-mediated degradation as shared with the FOX multigene family. This, to our knowledge, is the first time a genotype associated with pre-eclampsia has been shown to directly limit first trimester extravillous trophoblast invasion, the earliest hallmark of pre-eclampsia.
Collapse
Affiliation(s)
- Marie van Dijk
- Department of Clinical Chemistry, VU University Medical Center, Amsterdam the Netherlands.
| | | | | | | | | | | | | |
Collapse
|
83
|
Chesik D, De Keyser J, Bron R, Fuhler GM. Insulin-like growth factor binding protein-1 activates integrin-mediated intracellular signaling and migration in oligodendrocytes. J Neurochem 2010; 113:1319-30. [PMID: 20345750 DOI: 10.1111/j.1471-4159.2010.06703.x] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
In multiple sclerosis (MS), oligodendrocytes in lesions are lost, leaving damaged tissue virtually devoid of these myelin-producing cells. Our group has recently demonstrated enhanced expression of insulin-like growth factor (IGF) binding protein-1 (IGFBP-1) in oligodendrocytes (CNPase(+)) localized adjacent to MS lesions. In the present study, we demonstrate IGF-1-independent actions of IGFBP-1 on OLN-93 oligodendroglial cells, including activation of kinases ERK1/2, focal adhesion kinase and p21-activated kinase as well as small monomeric GTPases Rac and Ral. Activation of these intracellular signaling components was inhibited by GRGDS peptide, indicating signaling through integrin receptors. While both IGF-1 and IGFBP-1 demonstrated rapid induction of actin polymerization, IGFBP-1 proved to be a more potent inducer of migration than IGF-1, inducing a threefold increased migration rate. Furthermore, through integrin receptor signaling IGFBP-1 induced rapid transient translocalization of intracellular Rac toward punctuated structures followed by translocation of Rac to the plasma membrane. Our results suggest that up-regulation of IGFBP-1 in oligodendrocytes in MS may serve two functions: (i) regulate IGF-1 actions, (ii) exert IGF-independent effects through its RGD sequence.
Collapse
Affiliation(s)
- Daniel Chesik
- Department of Neurology, University Medical Center Groningen, Groningen, The Netherlands.
| | | | | | | |
Collapse
|
84
|
Abstract
In neutrophils, the phosphoinositide 3-kinase/Akt signaling cascade is involved in migration, degranulation, and O(2)(-) production. However, it is unclear whether the Akt kinase isoforms have distinct functions in neutrophil activation. Here we report functional differences between the 2 major Akt isoforms in neutrophil activation on the basis of studies in which we used individual Akt1 and Akt2 knockout mice. Akt2(-/-) neutrophils exhibited decreased cell migration, granule enzyme release, and O(2)(-) production compared with wild-type and Akt1(-/-) neutrophils. Surprisingly, Akt2 deficiency and pharmacologic inhibition of Akt also abrogated phorbol ester-induced O(2)(-) production, which was unaffected by treatment with the phosphoinositide 3-kinase inhibitor LY294002. The decreased O(2)(-) production in Akt2(-/-) neutrophils was accompanied by reduced p47(phox) phosphorylation and its membrane translocation, suggesting that Akt2 is important for the assembly of phagocyte nicotinamide adenine dinucleotide phosphate oxidase. In wild-type neutrophils, Akt2 but not Akt1 translocated to plasma membrane upon chemoattractant stimulation and to the leading edge in polarized neutrophils. In the absence of Akt2, chemoattractant-induced Akt protein phosphorylation was significantly reduced. These results demonstrate a predominant role of Akt2 in regulating neutrophil functions and provide evidence for differential activation of the 2 Akt isoforms in neutrophils.
Collapse
|
85
|
Vasudevan KM, Garraway LA. AKT Signaling in Physiology and Disease. Curr Top Microbiol Immunol 2010; 347:105-33. [DOI: 10.1007/82_2010_66] [Citation(s) in RCA: 65] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
|
86
|
Bristow JM, Sellers MH, Majumdar D, Anderson B, Hu L, Webb DJ. The Rho-family GEF Asef2 activates Rac to modulate adhesion and actin dynamics and thereby regulate cell migration. J Cell Sci 2009; 122:4535-46. [PMID: 19934221 DOI: 10.1242/jcs.053728] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Asef2 is a recently identified Rho-family guanine nucleotide exchange factor (GEF) that has been implicated in the modulation of actin, but its function in cell migration and adhesion dynamics is not well understood. In this study, we show that Asef2 is an important regulator of cell migration and adhesion assembly and disassembly (turnover). Asef2 localizes with actin at the leading edge of cells. Knockdown of endogenous Asef2 impairs migration and significantly slows the turnover of adhesions. Asef2 enhances both Rac1 and Cdc42 activity in HT1080 cells, but only Rac1 is crucial for the Asef2-promoted increase in migration and adhesion turnover. Phosphoinositide 3-kinase (PI3K) and the serine/threonine kinase Akt are also essential for the Asef2-mediated effects on migration and adhesion turnover. Consistent with this, Asef2 increases the amount of active Akt at the leading edge of cells. Asef2 signaling leads to an overall decrease in Rho activity, which is crucial for stimulating migration and adhesion dynamics. Thus, our results reveal an important new role for Asef2 in promoting cell migration and rapid adhesion turnover by coordinately regulating the activities of Rho-family GTPases.
Collapse
Affiliation(s)
- Jeanne M Bristow
- Department of Biological Sciences, Vanderbilt University, Nashville, Tennessee 37235, USA
| | | | | | | | | | | |
Collapse
|
87
|
Huang WC, Hung MC. Induction of Akt activity by chemotherapy confers acquired resistance. J Formos Med Assoc 2009; 108:180-94. [PMID: 19293033 DOI: 10.1016/s0929-6646(09)60051-6] [Citation(s) in RCA: 79] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023] Open
Abstract
Resistance to chemotherapy is a major cause of treatment failure in human cancer. Accumulating evidence has indicated that the acquisition of resistance to chemotherapeutic drugs involves the activation of the PI3K/Akt pathway. Modulating Akt activity in response to chemotherapy has been observed often in chemoresistant cancers. The potential molecular mechanisms by which chemotherapeutic agents activate the PI3K/Akt pathway are emerging. Activation of this pathway evades the cytotoxic effects of chemotherapeutic agents via regulation of essential cellular functions such as protein synthesis, antiapoptosis, survival and proliferation in cancer. How chemotherapeutic agents induce Akt activation and how activated Akt confers chemoresistance through regulation of signaling networks are discussed in this review. Combining PI3K/Akt inhibitors with standard chemotherapy has been successful in increasing the efficacy of chemotherapeutic agents both in vivo and in vitro. Several small molecules have been developed to specifically target PI3K/Akt and other components of this pathway, which in combination with chemotherapy may be a valid approach to overcome therapeutic resistance. We propose several feedback and feedforward regulatory mechanisms of signaling networks for maintenance of the Akt activity for cell survival. These regulatory mechanisms may limit the efficacy of PI3K/Akt-targeted therapy; therefore, disruption of these mechanisms may be an effective strategy for development of novel anti-cancer therapies.
Collapse
Affiliation(s)
- Wei-Chien Huang
- Center for Molecular Medicine and Graduate Institute of Cancer Biology, China Medical University and Hospital, and Department of Biotechnology, Asia University, Taichung, Taiwan.
| | | |
Collapse
|
88
|
Gonzalez E, McGraw TE. The Akt kinases: isoform specificity in metabolism and cancer. Cell Cycle 2009; 8:2502-8. [PMID: 19597332 DOI: 10.4161/cc.8.16.9335] [Citation(s) in RCA: 358] [Impact Index Per Article: 23.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
The Akt (PKB) protein kinases are critical regulators of human physiology that control an impressive array of diverse cellular functions, including the modulation of growth, survival, proliferation and metabolism. The Akt kinase family is comprised of three highly homologous isoforms: Akt1 (PKBalpha), Akt2 (PKBbeta) and Akt3 (PKBgamma). Phenotypic analyses of Akt isoform knockout mice documented Akt isoform specific functions in the regulation of cellular growth, glucose homeostasis and neuronal development. Those studies establish that the functions of the different Akt kinases are not completely overlapping and that isoform-specific signaling contributes to the diversity of Akt activities. However, despite these important advances, a thorough understanding about the specific roles of Akt family members and the molecular mechanisms that determine Akt isoform functional specificity will be essential to elucidate the complexity of Akt regulated cellular processes and how Akt isoform-specific deregulation might contribute to disease states. Here, we summarize recent advances in understanding the roles of Akt isoforms in the regulation of metabolism and cancer, and possible mechanisms contributing to Akt isoform functional specificity.
Collapse
Affiliation(s)
- Eva Gonzalez
- Department of Biochemistry, Weill Cornell Medical College, New York, NY 10065, USA
| | | |
Collapse
|
89
|
Fan Y, Gong Y, Ghosh PK, Graham LM, Fox PL. Spatial coordination of actin polymerization and ILK-Akt2 activity during endothelial cell migration. Dev Cell 2009; 16:661-74. [PMID: 19460343 DOI: 10.1016/j.devcel.2009.03.009] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2008] [Revised: 02/04/2009] [Accepted: 03/11/2009] [Indexed: 10/20/2022]
Abstract
Eukaryotic cell migration proceeds by cycles of protrusion, adhesion, and contraction, regulated by actin polymerization, focal adhesion assembly, and matrix degradation. However, mechanisms coordinating these processes remain largely unknown. Here, we show that local regulation of thymosin-beta4 (Tbeta4) binding to actin monomer (G-actin) coordinates actin polymerization with metalloproteinase synthesis to promote endothelial cell motility. In particular and quite unexpectedly, FRET analysis reveals diminished interaction between Tbeta4 and G-actin at the cell leading edge despite their colocalization there. Profilin-dependent dissociation of G-actin-Tbeta4 complexes simultaneously liberates actin for filament assembly and facilitates Tbeta4 binding to integrin-linked kinase (ILK) in the lamellipodia. Tbeta4-ILK complexes then recruit and activate Akt2, resulting in matrix metalloproteinase-2 production. Thus, the actin-Tbeta4 complex constitutes a latent coordinating center for cell migratory behavior, allowing profilin to initiate a cascade of events at the leading edge that couples actin polymerization to matrix degradation.
Collapse
Affiliation(s)
- Yi Fan
- Department of Cell Biology, Lerner Research Institute, Cleveland Clinic, Cleveland, OH 44195, USA
| | | | | | | | | |
Collapse
|
90
|
Cao C, Huang X, Han Y, Wan Y, Birnbaumer L, Feng GS, Marshall J, Jiang M, Chu WM. Galpha(i1) and Galpha(i3) are required for epidermal growth factor-mediated activation of the Akt-mTORC1 pathway. Sci Signal 2009; 2:ra17. [PMID: 19401591 DOI: 10.1126/scisignal.2000118] [Citation(s) in RCA: 107] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
The precise mechanism whereby epidermal growth factor (EGF) activates the serine-threonine kinase Akt and the mammalian target of rapamycin (mTOR) complex 1 (mTORC1) remains elusive. Here, we report that the alpha subunits of the heterotrimeric guanine nucleotide-binding proteins (G proteins) Galpha(i1) and Galpha(i3) are critical for this activation process. Both Galpha(i1) and Galpha(i3) formed complexes with growth factor receptor binding 2 (Grb2)-associated binding protein 1 (Gab1) and the EGF receptor (EGFR) and were required for the phosphorylation of Gab1 and its subsequent interaction with the p85 subunit of phosphatidylinositol 3-kinase in response to EGF. Loss of Galpha(i1) and Galpha(i3) severely impaired the activation of Akt and of p70 S6 kinase and 4E-BP1, downstream targets of mTORC1, in response to EGF, heparin-binding EGF-like growth factor, and transforming growth factor alpha, but not insulin, insulin-like growth factor, or platelet-derived growth factor. In addition, ablation of Galpha(i1) and Galpha(i3) largely inhibited EGF-induced cell growth, migration, and survival and the accumulation of cyclin D1. Overall, this study suggests that Galpha(i1) and Galpha(i3) lie downstream of EGFR, but upstream of Gab1-mediated activation of Akt and mTORC1, thus revealing a role for Galpha(i) proteins in mediating EGFR signaling.
Collapse
Affiliation(s)
- Cong Cao
- Department of Molecular Microbiology and Immunology, Brown University, Providence, RI 02912, USA
| | | | | | | | | | | | | | | | | |
Collapse
|
91
|
Gayer CP, Chaturvedi LS, Wang S, Alston B, Flanigan TL, Basson MD. Delineating the signals by which repetitive deformation stimulates intestinal epithelial migration across fibronectin. Am J Physiol Gastrointest Liver Physiol 2009; 296:G876-85. [PMID: 19179620 PMCID: PMC2670672 DOI: 10.1152/ajpgi.90648.2008] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Repetitive strain stimulates intestinal epithelial migration across fibronectin via focal adhesion kinase (FAK), Src, and extracellular signal-related kinase (ERK) although how these signals act and interact remains unclear. We hypothesized that PI3K is central to this pathway. We subjected Caco-2 and intestinal epithelial cell-6 cells to 10 cycles/min deformation on flexible fibronectin-coated membranes, assayed migration by wound closure, and signaling by immunoblots. Strain stimulated PI3K, AKT, glycogen synthase kinase (GSK), and p38 phosphorylation. Blocking each kinase prevented strain stimulation of migration. Blocking PI3K prevented strain-stimulated ERK and p38 phosphorylation. Blocking AKT did not. Downstream, blocking PI3K, AKT, or ERK inhibited strain-induced GSK-Ser9 phosphorylation. Upstream of AKT, reducing FAK or Rac1 by siRNA blocked strain-stimulated AKT phosphorylation, but inhibiting Src by PP2 or siRNA did not. Transfection with FAK point mutants at Tyr397, Tyr576/577, or Tyr925 demonstrated that only FAK925 phosphorylation is required for strain-stimulated AKT phosphorylation. Myosin light chain activation by strain required FAK, Rac1, PI3K, AKT, GSK, and ERK but not Src or p38. Finally, blebbistatin, a nonmuscle myosin II inhibitor, blocked the motogenic effect of strain downstream of myosin light chain. Thus strain stimulates intestinal epithelial migration across fibronectin by a complex pathway including Src, FAK, Rac1, PI3K, AKT, GSK, ERK, p38, myosin light chain, and myosin II.
Collapse
Affiliation(s)
- Christopher P. Gayer
- Departments of Surgery, Anatomy, and Cell Biology, John D. Dingell VA Medical Center, Wayne State University, Detroit and Michigan State University, Lansing, Michigan
| | - Lakshmi S. Chaturvedi
- Departments of Surgery, Anatomy, and Cell Biology, John D. Dingell VA Medical Center, Wayne State University, Detroit and Michigan State University, Lansing, Michigan
| | - Shouye Wang
- Departments of Surgery, Anatomy, and Cell Biology, John D. Dingell VA Medical Center, Wayne State University, Detroit and Michigan State University, Lansing, Michigan
| | - Brittany Alston
- Departments of Surgery, Anatomy, and Cell Biology, John D. Dingell VA Medical Center, Wayne State University, Detroit and Michigan State University, Lansing, Michigan
| | - Thomas L. Flanigan
- Departments of Surgery, Anatomy, and Cell Biology, John D. Dingell VA Medical Center, Wayne State University, Detroit and Michigan State University, Lansing, Michigan
| | - Marc D. Basson
- Departments of Surgery, Anatomy, and Cell Biology, John D. Dingell VA Medical Center, Wayne State University, Detroit and Michigan State University, Lansing, Michigan
| |
Collapse
|
92
|
Rotwein P, Wilson EM. Distinct actions of Akt1 and Akt2 in skeletal muscle differentiation. J Cell Physiol 2009; 219:503-11. [PMID: 19142853 DOI: 10.1002/jcp.21692] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Differentiation, maturation, and repair of skeletal muscle requires ongoing cooperation between signaling cascades activated by hormones and growth factors, and intrinsic regulatory programs controlled by myogenic transcription factors. The insulin-like growth factor--phosphatidylinositol-3 kinase--Akt pathway has been implicated in muscle growth and regeneration after injury, in counteracting sarcopenia during aging, and in maintaining muscle cell viability. Here we present evidence for distinct roles for Akt1 and Akt2 in different phases of muscle differentiation. Targeted knockdown of either Akt had no effect on C2 myoblast proliferation, even though Akt1 concentrations are markedly higher than Akt2 levels under growth-promoting conditions. Akt2 concentrations rose by nearly an order of magnitude during muscle differentiation, while Akt1 levels remained constant, yet loss of either protein did not increase myoblast death. Rather, knockdown or genetic knockout of Akt1 blocked differentiation at its earliest stages, preventing induction of muscle-specific proteins and inhibiting formation of multinucleated myofibers, while myoblasts lacking Akt2 differentiated normally, although resultant myofibers were thinner and incorporated fewer nuclei than controls. Forced expression of knockdown-resistant Akt1 partially reversed the deficit in differentiation seen in myoblasts lacking Akt1. Our results define isoform-specific Akt actions in muscle cells, and demonstrate that both Akts are necessary for full myoblast differentiation and maturation.
Collapse
Affiliation(s)
- Peter Rotwein
- Department of Biochemistry and Molecular Biology, Oregon Health & Science University, Portland, Oregon 97239-3098, USA.
| | | |
Collapse
|
93
|
Yoeli-Lerner M, Chin YR, Hansen CK, Toker A. Akt/protein kinase b and glycogen synthase kinase-3beta signaling pathway regulates cell migration through the NFAT1 transcription factor. Mol Cancer Res 2009; 7:425-32. [PMID: 19258413 DOI: 10.1158/1541-7786.mcr-08-0342] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
The phosphoinositide 3-kinase (PI3K) pathway regulates a multitude of cellular processes. Deregulation of PI3K signaling is often observed in human cancers. A major effector of PI3K is Akt/protein kinase B (PKB). Recent studies have pointed to distinct roles of Akt/PKB isoforms in cancer cell signaling. Studies have shown that Akt1 (PKBalpha) can attenuate breast cancer cell motility, whereas Akt2 (PKBbeta) enhances this phenotype. Here, we have evaluated the mechanism by which Akt1 blocks the migration of breast cancer cells through the transcription factor NFAT. A major effector of Akt/PKB is glycogen synthase kinase-3beta (GSK-3beta), also a NFAT kinase. Inhibition of GSK-3beta using short hairpin RNA or a selective inhibitor potently blocks breast cancer cell migration concomitant with a reduction in NFAT activity. GSK-3beta-mediated inhibition of NFAT activity is due to proteasomal degradation. Experiments using GSK-3beta mutants, which are unresponsive to Akt/PKB, reveal that inhibition of cell migration by Akt/PKB is mediated by GSK-3beta. These effects are recapitulated at the levels of NFAT degradation by the proteasome. Our studies show that activation of Akt/PKB leads to inactivation of the effector GSK-3beta and the outcome of this signaling event is degradation of NFAT by the proteasome and subsequent inhibition of cell migration.
Collapse
Affiliation(s)
- Merav Yoeli-Lerner
- Department of Pathology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts 02215, USA
| | | | | | | |
Collapse
|
94
|
Zhang B, Ma Y, Guo H, Sun B, Niu R, Ying G, Zhang N. Akt2 is required for macrophage chemotaxis. Eur J Immunol 2009; 39:894-901. [DOI: 10.1002/eji.200838809] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
|
95
|
|
96
|
Yun SJ, Tucker DF, Kim EK, Kim MS, Do KH, Ha JM, Lee SY, Yun J, Kim CD, Birnbaum MJ, Bae SS. Differential regulation of Akt/protein kinase B isoforms during cell cycle progression. FEBS Lett 2009; 583:685-90. [PMID: 19166849 DOI: 10.1016/j.febslet.2009.01.005] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2008] [Revised: 12/22/2008] [Accepted: 01/11/2009] [Indexed: 10/21/2022]
Abstract
Phosphatidylinositol 3-kinase pathways play key regulatory roles in cell cycle progression into S phase. In this study, we demonstrated that Akt1/PKBalpha isoform plays an essential role in G(1)/S transition and proliferation. Cells lacking Akt1/PKBalpha showed an attenuated proliferation as well as G(1)/S transition, whereas cells lacking Akt2/PKBbeta showed normal proliferation and G(1)/S transition. The effect of Akt1/PKBalpha on cell proliferation and G(1)/S transition was completely abolished by swapping pleckstrin homology (PH) domain with that of Akt2/PKBbeta. Finally, full activation of Akt/PKB and cyclin D expression was achieved by the Akt1/PKBalpha or chimeric proteins containing the PH domain of Akt1/PKBalpha indicating that the PH domain of Akt1/PKBalpha provides full kinase activity and is necessary for the G(1)/S transition.
Collapse
Affiliation(s)
- Sung Ji Yun
- MRC for Ischemic Tissue Regeneration and Medical Research Institute, Department of Pharmacology, School of Medicine, Pusan National University, Ami-dong 1-ga 10, Seo-gu, Busan 602-739, Republic of Korea
| | | | | | | | | | | | | | | | | | | | | |
Collapse
|
97
|
Moro L, Arbini AA, Yao JL, di Sant'Agnese PA, Marra E, Greco M. Mitochondrial DNA depletion in prostate epithelial cells promotes anoikis resistance and invasion through activation of PI3K/Akt2. Cell Death Differ 2008; 16:571-83. [PMID: 19079138 DOI: 10.1038/cdd.2008.178] [Citation(s) in RCA: 93] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
Neoplastic transformation of prostate epithelium involves aberrant activation of anti-apoptotic and pro-invasive pathways triggered by multiple poorly understood genetic events. We demonstrated earlier that depletion of mitochondrial DNA (mtDNA) induces prostate cancer progression. Here, using normal prostate epithelial PNT1A cells we demonstrate that mtDNA depletion prevents detachment-induced apoptosis (anoikis) and promotes migratory capabilities onto basement membrane proteins through upregulation of p85 and p110 phosphatidylinositol 3-kinase (PI3K) subunits, which results in Akt2 activation and phosphorylation of downstream substrates GSK3beta, c-Myc, MMP-9, Mdm2, and p53. Pharmacological or genetic PI3K inhibition, siRNA-mediated Akt2 depletion, as well as mtDNA reconstitution were sufficient to restore sensitivity to anoikis and curtail cell migration. Moreover, Akt2 activation induced glucose transporter 1 (GLUT1) expression, glucose uptake, and lactate production, common phenotypic changes seen in neoplastic cells. In keeping with these findings, several prostate carcinoma cell lines displayed reduced mtDNA content and increased PI3K/Akt2 levels when compared to normal PNT1A cells, and Akt2 downregulation prevented their survival, migration and glycolytic metabolism. On a tissue microarray, we also found a statistically significant decrease in mtDNA-encoded cytochrome oxidase I in prostate carcinomas. Taken together, these results provide novel mechanistic evidence supporting the notion that mtDNA mutations may confer survival and migratory advantage to prostate cancer cells through Akt2 signaling.
Collapse
Affiliation(s)
- L Moro
- Institute of Biomembranes and Bioenergetics, National Research Council (CNR), Bari, Italy
| | | | | | | | | | | |
Collapse
|
98
|
Chin YR, Toker A. Function of Akt/PKB signaling to cell motility, invasion and the tumor stroma in cancer. Cell Signal 2008; 21:470-6. [PMID: 19110052 DOI: 10.1016/j.cellsig.2008.11.015] [Citation(s) in RCA: 204] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2008] [Accepted: 11/24/2008] [Indexed: 01/02/2023]
Abstract
The serine/threonine protein kinase Akt is a major signal transducer of the phosphoinositide 3-kinase (PI 3-K) pathway in all cells and tissues and plays a pivotal role in the maintenance of cellular processes including cell growth, proliferation, survival and metabolism. The frequent aberrant activation of the PI 3-K/Akt pathway in human cancer has made it an attractive therapeutic target. Numerous studies have provided a comprehensive understanding of the specific functions of Akt signaling in cancer cells as well as the surrounding tumor microenvironment and this has informed and enabled the development of therapeutic drugs to target both PI 3-K and Akt. However, recent studies have provided evidence for distinct functions of the three mammalian Akt isoforms, particularly with respect to the regulation of cell motility and metastasis of breast cancer. Here we discuss the mechanisms by which Akt signaling contributes to invasive migration and tumor metastasis, and highlight recent advances in our understanding of the contribution of the Akt pathway in the tumor-associated stroma.
Collapse
Affiliation(s)
- Y Rebecca Chin
- Department of Pathology, Beth Israel Deaconess Medical Center, 330 Brookline Avenue, EC/CLS-528, Boston, MA 02215, USA.
| | | |
Collapse
|
99
|
Gayer CP, Chaturvedi LS, Wang S, Craig DH, Flanigan T, Basson MD. Strain-induced proliferation requires the phosphatidylinositol 3-kinase/AKT/glycogen synthase kinase pathway. J Biol Chem 2008; 284:2001-11. [PMID: 19047055 DOI: 10.1074/jbc.m804576200] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
The intestinal epithelium is repetitively deformed by shear, peristalsis, and villous motility. Such repetitive deformation stimulates the proliferation of intestinal epithelial cells on collagen or laminin substrates via ERK, but the upstream mediators of this effect are poorly understood. We hypothesized that the phosphatidylinositol 3-kinase (PI3K)/AKT cascade mediates this mitogenic effect. PI3K, AKT, and glycogen synthase kinase-3beta (GSK-3beta) were phosphorylated by 10 cycles/min strain at an average 10% deformation, and pharmacologic blockade of these molecules or reduction by small interfering RNA (siRNA) prevented the mitogenic effect of strain in Caco-2 or IEC-6 intestinal epithelial cells. Strain MAPK activation required PI3K but not AKT. AKT isoform-specific siRNA transfection demonstrated that AKT2 but not AKT1 is required for GSK-3beta phosphorylation and the strain mitogenic effect. Furthermore, overexpression of AKT1 or an AKT chimera including the PH domain and hinge region of AKT2 and the catalytic domain and C-tail of AKT1 prevented strain activation of GSK-3beta, but overexpression of AKT2 or a chimera including the PH domain and hinge region of AKT1 and the catalytic domain and C-tail of AKT2 did not. These data delineate a role for PI3K, AKT2, and GSK-3beta in the mitogenic effect of strain. PI3K is required for both ERK and AKT2 activation, whereas AKT2 is sequentially required for GSK-3beta. Furthermore, AKT2 specificity requires its catalytic domain and tail region. Manipulating this pathway may prevent mucosal atrophy and maintain the mucosal barrier in conditions such as ileus, sepsis, and prolonged fasting when peristalsis and villous motility are decreased and the mucosal barrier fails.
Collapse
Affiliation(s)
- Christopher P Gayer
- Department of Surgery, John D. Dingell Veterans Affairs Medical Center, Detroit, Michigan 48301, USA
| | | | | | | | | | | |
Collapse
|
100
|
Kim EK, Yun SJ, Do KH, Kim MS, Cho M, Suh DS, Kim CD, Kim JH, Birnbaum MJ, Bae SS. Lysophosphatidic acid induces cell migration through the selective activation of Akt1. Exp Mol Med 2008; 40:445-52. [PMID: 18779657 DOI: 10.3858/emm.2008.40.4.445] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022] Open
Abstract
Akt plays pivotal roles in many physiological responses including growth, proliferation, survival, metabolism, and migration. In the current studies, we have evaluated the isoform-specific role of akt in lysophosphatidic acid (LPA)-induced cell migration. Ascites from ovarian cancer patients (AOCP) induced mouse embryo fibroblast (MEF) cell migration in a dose-dependent manner. On the other hand, ascites from liver cirrhosis patients (ALCP) did not induce MEF cell migration. AOCP-induced MEF cell migration was completely blocked by pre-treatment of cells with LPA receptor antagonist, Ki16425. Both LPA- and AOCP-induced MEF cell migration was completely attenuated by PI3K inhibitor, LY294002. Furthermore, cells lacking Akt1 displayed defect in LPA-induced cell migration. Re-expression of Akt1 in DKO (Akt1-/-Akt2-/-) cells restored LPA-induced cell migration, whereas re-expression of Akt2 in DKO cells could not restore the LPA-induced cell migration. Finally, Akt1 was selectively phosphorylated by LPA and AOCP stimulation. These results suggest that LPA is a major factor responsible for AOCP-induced cell migration and signaling specificity of Akt1 may dictate LPA-induced cell migration.
Collapse
Affiliation(s)
- Eun Kyoung Kim
- MRC for Ischemic Tissue Regeneration and Medical Research Institute, Department of Internal Medicine, School of Medicine, Pusan National University, Busan 602-739, Korea
| | | | | | | | | | | | | | | | | | | |
Collapse
|