• Title, Summary, Keyword: Akt

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Discovery and Evaluation of Polymorphisms in the AKT2 and AKT3 Promoter Regions for Risk of Korean Lung Cancer

  • Sung, Jae-Sook;Park, Kyong-Hwa;Kim, Seung-Tae;Kim, Yeul-Hong
    • Genomics & Informatics
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    • v.10 no.3
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    • pp.167-174
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    • 2012
  • AKT is a signal transduction protein that plays a central role in the tumorigenesis. There are 3 mammalian isoforms of this serine/threonine protein kinase-AKT1, AKT2, and AKT3-showing a broad tissue distribution. We first discovered 2 novel polymorphisms (AKT2 -9826 C/G and AKT3 -811 A/G), and we confirmed 6 known polymorphisms (AKT2 -9473 C/T, AKT2 -9151 C/T, AKT2 -9025 C/T, AKT2 -8618G/A, AKT3 -675 A/-, and AKT3 -244 C/T) of the AKT2 and AKT3 promoter region in 24 blood samples of Korean lung cancer patients using direct sequencing. To evaluate the role of AKT2 and AKT3 polymorphisms in the risk of Korean lung cancer, genotypes of the AKT2 and AKT3 polymorphisms (AKT2 -9826 C/G, AKT2 -9473 C/T, AKT2 -9151 C/T, AKT2 -9025 C/T, AKT2 -8618G/A, and AKT3 -675 A/-) were determined in 360 lung cancer patients and 360 normal controls. Statistical analyses revealed that the genotypes and haplotypes in the AKT2 and AKT3 promoter regions were not significantly associated with the risk of lung cancer in the Korean population. These results suggest that polymorphisms of the AKT2 and AKT3 promoter regions do not contribute to the genetic susceptibility to lung cancer in the Korean population.

Expression and Activation of Akt/PKB Protein Kinase using Escherichia coli (대장균을 이용한 Akt/PKB Protein Kinase의 발현 및 활성화)

  • Lee, Jae-Hag
    • Microbiology and Biotechnology Letters
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    • v.37 no.2
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    • pp.105-109
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    • 2009
  • Among signal transduction systems by protein phosphorylation Akt/PKB protein kinase which is one of serine/threonine kinases, is known to regulate the survival and death of the cell and glucose metabolism. Thus, Akt/PKB protein kinase has been used as one of the target proteins to find anti-cancer agents from natural products. In this study, human Akt/PKB protein kinase was expressed in Escherichia coli expression system for the mass production. Human Akt/PKB protein kinase expressed in E. coli formed inclusion body under the general condition. However, most of the expressed protein was solubilized under the culture temperature at $27^{\circ}C$ and 0.01-0.09 mM of IPTG for induction of the protein expression. The expressed protein was purified using $Ni^{2+}$-NTA agarose column and confirmed by using anti-Akt antibody. Subsequently, the purified human Akt/PKB protein kinase was activated by in vitro phosphorylation using cellular extract containing kinases. The activated protein was confirmed to phosphorylate the specific fluorescent peptide specially designed as the artificial substrate for Akt/PKB protein kinase.

Anti-Proliferative Effects of Selenium in HT-29 Colon Cancer Cells via Inhibition of Akt (HT-29 대장암세포에서 Akt 활성 저해에 따른 셀레늄의 세포 증식억제 효과)

  • Park, Song-Yi;Kim, In-Seop;Lee, Se-Hee;Lee, Sol-Hwa;Jung, Da-Woon;Park, Ock-Jin;Kim, Young-Min
    • Journal of Life Science
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    • v.22 no.1
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    • pp.55-61
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    • 2012
  • Akt is known to play an important role in cell proliferation and differentiation, and is also over-expressed in several types of cancer cells. In this study, we explored the anti-proliferative effects of selenium in HT-29 colon cancer cells, mediated through effects on Akt and COX-2. Selenium treatments at different concentrations and for different durations inhibited proliferation of HT-29 colon cancer cells and increased apoptotic cell death. Selenium treatment decreased Akt phosphorylation and COX-2 expression. Treatment with LY294002 (an Akt inhibitor) decreased proliferation of HT-29 cells, while a combined treatment with LY294002 and selenium resulted in even further decreases in cell proliferation. Inactivation of Akt by Akt siRNA treatment abolished these inhibitory effects on cell growth. COX-2 expression decreased in Akt transfected cells compared to non-transfected cells. These results suggest that selenium induced both anti-proliferative and apoptotic effects by inhibiting Akt phosphorylation and COX-2 expression. Selenium treatment also appeared to induce synergistic anti-proliferative effects by inhibition of Akt in HT-29 colon cancer cells.

Direct tyrosine phosphorylation of Akt/PKB by epidermal growth factor receptor (EGF 수용체에 의한 Akt/PKB의 tyrosine 인산화에 대한 연구)

  • Bae, Sun-Sik;Choi, Jang-Hyun;Yun, Sung-Ji;Kim, Eun-Kyung;Oh, Yong-Suk;Kim, Chi-Dae;Suh, Pann-Ghill
    • Journal of Life Science
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    • v.17 no.2
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    • pp.185-191
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    • 2007
  • Akt/PKB plays pivotal roles in many physiological responses such as proliferation, differentiation, apoptosis, and angiogenesis. Here we show that tyrosine phosphorylation of Akt/PKB is essential for the subsequent phosphorylation at $Thr^{\308}$. Tyrosine phosphorylation of Akt/PKB was induced by stimulation of COS-7 cells with epidermal growth factor receptor (EGF) and its phosphorylation was significantly enhanced by constitutive targeting of Akt/PKB to the plasma membrane by myristoylation. Interestingly, incubation of affinity purified Myc-tagged Akt/PKB with purified EGF receptor resulted in tyrosine phosphorylation as well as $Ser^{\473}$ phosphorylation of Akt/PKB. In addition, tyrosine-phosphorylated Akt/PKB could directly associate with activated EGF receptor in vitro. Finally, alanine mutation at putative tyrosine phosphorylation site $(Tyr^{\326})$ abolished EGF induced $Thr^{\308}$ phosphorylation of wild type as well as constitutively active form of Akt/PKB. Given these results we suggest here that direct tyrosine phosphorylation of Akt/PKB by EGF receptor could be another mechanism of EGF-induced control of many physiological responses.

Regulation of Skeletal Muscle Differentiation by Akt (Akt에 의한 근육세포의 분화 조절)

  • Woo, Dae-Han;Yun, Sung-Ji;Kim, Eun-Kyoung;Ha, Jung-Min;Shin, Hwa-Kyoung;Bae, Sun-Sik
    • Journal of Life Science
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    • v.22 no.4
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    • pp.447-455
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    • 2012
  • Akt plays an important role in a variety of cellular physiologies such as growth, proliferation, and differentiation. In skeletal muscle, Akt has been implicated in regulating regeneration, hypertrophy, and atrophy. In this study, the role of Akt has been examined during skeletal muscle differentiation. Culturing C2C12 myoblasts under low serum (1% horse serum) and high density converted cell morphology from a round shape to an elongated and multi-nucleated shape. Morphological changes were initiated from day 2 of differentiation. In addition, the expression of both myogenin G and myogenin D was elevated from day 2 of differentiation. Skeletal muscle differentiation was abolished by silencing Akt1 or Akt2, but was significantly enhanced by the over-expression of either Akt1 or Akt2. The activation of Akt was observed from day 2 of differentiation and disappeared after day 7. The expression of kruppel-like factor 4 was observed from day 6 of differentiation. Moreover, this expression was blocked in cells silencing either Akt1 or Akt2. In addition, the promoter activity of kruppel-like factor 4 was significantly reduced in cells silencing Akt1 or Akt2. These results suggest that Akt regulates skeletal muscle differentiation through the regulation of kruppel-like factor 4 expression.

Regulation of AKT Activity by Inhibition of the Pleckstrin Homology Domain-PtdIns(3,4,5)P3 Interaction Using Flavonoids

  • Kang, Yerin;Jang, Geupil;Ahn, Seunghyun;Lee, Youngshim;Shin, Soon Young;Yoon, Youngdae
    • Journal of Microbiology and Biotechnology
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    • v.28 no.8
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    • pp.1401-1411
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    • 2018
  • The serine-threonine kinase AKT plays a pivotal role in tumor progression and is frequently overactivated in cancer cells; this protein is therefore a critical therapeutic target for cancer intervention. We aimed to identify small molecule inhibitors of the pleckstrin homology (PH) domain of AKT to disrupt binding of phosphatidylinositol-3,4,5-trisphosphate (PIP3), thereby downregulating AKT activity. Liposome pulldown assays coupled with fluorescence spectrometry were used to screen flavonoids for inhibition of the AKT PH-PIP3 interaction. Western blotting was used to determine the effects of the inhibitors on AKT activation in cancer cells, and in silico docking was used for structural analysis and optimization of inhibitor structure. Several flavonoids showing up to 50% inhibition of the AKT PH-PIP3 interaction decreased the level of AKT activation at the cellular level. In addition, the modified flavonoid showed increased inhibitory effects and the approach would be applied to develop anticancer drug candidates. In this study, we provide a rationale for targeting the lipid-binding domain of AKT, rather than the catalytic kinase domain, in anticancer drug development.

Melatonin Induces Akt Phosphorylation through Melatonin Receptor- and PI3K-Dependent Pathways in Primary Astrocytes

  • Kong, Pil-Jae;Byun, Jong-Seon;Lim, So-Young;Lee, Jae-Jun;Hong, Sung-Jun;Kwon, Kwang-Jun;Kim, Sung-Soo
    • The Korean Journal of Physiology and Pharmacology
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    • v.12 no.2
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    • pp.37-41
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    • 2008
  • Melatonin has been reported to protect neurons from a variety of neurotoxicity. However, the underlying mechanism by which melatonin exerts its neuroprotective property has not yet been clearly understood. We previously demonstrated that melatonin protected kainic acid-induced neuronal cell death in mouse hippocampus, accompanied by sustained activation of Akt, a critical mediator of neuronal survival. To further elucidate the neuroprotective action of melatonin, we examined in the present study the causal mechanism how Akt signaling pathway is regulated by melatonin in a rat primary astrocyte culture model. Melatonin resulted in increased astrocytic Akt phosphorylation, which was significantly decreased with wortmannin, a specific inhibitor of PI3K, suggesting that activation of Akt by melatonin is mediated through the PI3K-Akt signaling pathway. Furthermore, increased Akt activation was also significantly decreased with luzindole, a non-selective melatonin receptor antagonist. As downstream signaling pathway of Akt activation, increased levels of CREB phoshorylation and GDNF expression were observed, which were also attenuated with wortmannin and luzindole. These results strongly suggest that melatonin exerts its neuroprotective property in astrocytes through the activation of plasma membrane receptors and then PI3K-Akt signaling pathway.

Nuclear Akt promotes neurite outgrowth in the early stage of neuritogenesis

  • Park, Ji-Hye;Lee, Sang-Bae;Lee, Kyung-Hoon;Ahn, Jee-Yin
    • BMB Reports
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    • v.45 no.9
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    • pp.521-525
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    • 2012
  • In addition to its pivotal role in neuronal survival, PI3K/Akt signaling is integral to neuronal differentiation and neurite outgrowth. However, the exact role of Akt in neuronal differentiation is still controversial. Here, we found that nuclear expression of CA-Akt resulted in unusual rapid neurite outgrowth and overexpression of KD-Akt caused multiple dendrite growth without specific axon elongation. Moreover, microarray data revealed that the expression of FOXQ1 expression was about 10-fold higher in cells with nuclear, active Akt than in control cells. Quantitative real-time PCR analysis showed that mRNA levels were upregulated in NLS-CA-Akt cells as compared to KD or EV cells. Furthermore, our FACS analysis demonstrated that overexpression of NLS-CA-Akt accumulate cells in the G1 phase within 24 h, fitting with the rapid sprouting of neuritis. Thus, our data implied that at least in this early time frame, the overexpression of nuclear, active Akt forced cells into neurite development through probably FOXQ1regulation.

Challenges for large size TV manufacturing;Process and Test Equipment

  • Kang, In-Doo;Brunner, Mathias;Tanaka, Tak;Sun, Sheng;Li, Julia
    • 한국정보디스플레이학회:학술대회논문집
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    • pp.1673-1675
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    • 2006
  • As the manufacturing capacity needs for large size LCD TV shifts very fast into next generation, processing and test equipment makers face more difficult challenges in accommodating productivity, reliability and lead time of panel makers as well as the prerequisite of high process quality. In this paper, AKT will discuss its new innovative productivity solutions in PECVD (Plasma Enhanced Chemical Vapor Deposition), as the key thin film process system, and EBT (Electron Beam Test), as the key array test system, for the huge glass size with surface dimension larger than 2 meter by 2 meter.

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Inhibitory Effects of Dithiolo-thione Derivative SWU-20009 on Akt Activity (Dithiolo-thione 계열 유도체 SWU-20009의 Akt활성 저해 효과)

  • 고종희;연승우;이홍섭;김태용;노동윤;신경순;홍순광;강상순
    • YAKHAK HOEJI
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    • v.48 no.2
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    • pp.105-110
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    • 2004
  • Akt (or Protein Kinase B; PKB) is a serine/threonine kinase and is activated by phosphoinositide 3-kinase (PI3K) pathway. Recent evidence indicates that the abnormal activities or expression of Akt is closely associated with cancer, diabetes and neuro-degenerative diseases. These findings mean that Akt is likely to be a new therapeutic target for the treatment of disease. Here, we screened the effects of dithiolo-dithione derivatives such as SWU-20004, SWU-20009 and SWU-20025 on Akt activities. Among these compounds, only SWU-20009 (2-Thioxo-[1,3]dithiolo[4,5- $\beta$][1,4]dithiine-5,6-dicarboxylic acid dimethyl ester) inhibited the growth of KATOIII cell at micromolar range of concentration. Further investigation also revealed that SWU-20009 inhibited cellular Akt activity and induced apoptotic cell death.