• 생명과학회지
• /
• 제26권10호
• /
• pp.1182-1188
• /
• 2016

Membrane associated guanylate kinase inverted-3 (MAGI-3)는 세포-세포 연접의 형성을 유도하는 막단백질인 membrane associated guanylate kinases (MAGUKs)의 한 종류 단백질로 140 kDa 크기를 가진다. MAGI-3는 PTEN/MMAC와 함께 협력하여 AKT/PKB의 kinase 활성을 조절하거나 MAPKs 신호전달경로로 ERK 활성을 조절로 한다. Coxsackievirus B3 (CVB3)는 가장 일반적으로 감염된 심근 세포 사멸으로 인한 바이러스성 심근염을 일으키는 enterovirus에 속하는 인간 병원체이다. 이전 연구에서 protein kinase B (PKB, 또는 AKT)와 extracellular signal-regulated kinases 1/2 (ERK1/2)의 활성은 HeLa 세포에서 CVB3 복제를 위해 필수적임이 밝혀졌다. 본 연구에서 enterovirus 복제와 AKT 신호 활성조절에서 MAGI-3의 역할을 검증하였다. MAGI-3-Flag의 발현은 CVB3 감염 후에 AKT 신호 활성과 viral capsid protein VP1의 발현을 유도하였으며 이는 MAGI-3에 의한 enterovirus 증식 조절을 보여주었다. AKT 신호는 MAGI-3 발현에 의해 enterovirus 감염과 함께 유의하게 증가하고 이것은 감염 바이러스의 증식을 활발하게 유도함을 확인하였다. 이 결과는 MAGI-3의 발현은 AKT와 ERK의 활성이 증가하고, 더 나아가 바이러스 증식과 연관이 있다는 것을 입증한다. MAGI-3는 아마도 AKT 신호 조절을 통해 enterovirus 증식 조절에 중요한 역할을 할 것으로 생각된다.

• 대한약학회:학술대회논문집
• /
• 대한약학회 2003년도 Proceedings of the Convention of the Pharmaceutical Society of Korea Vol.2-2
• /
• pp.76.2-76.2
• /
• 2003

Although sphingosine-1-phosphate (S1P) is a well-known mitogen, our results show that S1P potently inhibits keratinocyte proliferation, and that this leads the inhibition of DNA synthesis. Interestingly, the prolonged activation of extracellular signal-regulated protein kinase (ERK) and the transient inactivation of Akt/protein kinase B (PKB) were also oberved in concert with the inhibition of keratinocyte proliferation by S1P. To further verify the anti-proliferative action of S1P, we examined changes in cell cycle related proteins. (omitted)

• 한국동물학회:학술대회논문집
• /
• 한국동물학회 2005년도 제60회 한국생물과학협회 정기학술발표대회
• /
• pp.18-18
• /
• 2005

• BMB Reports
• /
• 제44권3호
• /
• pp.205-210
• /
• 2011

Insulin has antiapoptotic activity in various cell types. However, the signaling pathways underlying the antiapoptotic activity of insulin is not yet known. This study was conducted to determine if cAMP affects the antiapoptotic activity of insulin and the activity of PI3K and ERK in CHO cells expressing human insulin receptors (CHO-IR). Insulin-stimulated ERK activity was completely suppressed by cAMP-elevating agents like as pertussis toxin (Ptx) and cholera toxin (Ctx) after 4 h treatment. Insulin-stimulated PKB/Akt activity was not affected at all. Ptx treatment together with insulin increased the number of apoptotic cells and the degree of DNA fragmentation. Ctx or 8-br-cAMP treatment also increased the number of apoptotic cells and stimulated the cleavage of caspase-3 and the hydrolysis of PARP. Taken together, cAMP antagonizes the antiapoptotic activity of insulin and the main target molecule of cAMP in this process is likely ERK, not PI3K-dependent PKB/Akt.

• BMB Reports
• /
• 제43권2호
• /
• pp.127-132
• /
• 2010

Phosphatidylinositol (3,4,5)-triphosphate ($PIP_3$) is a lipid second messenger that employs a wide range of downstream effector proteins for the regulation of cellular processes, including cell survival, polarization and proliferation. One of the most well characterized cytoplasmic targets of $PIP_3$, serine/threonine protein kinase B (PKB)/Akt, promotes cell survival by directly interacting with nucleophosmin (NPM)/B23, the nuclear target of $PIP_3$. Here, we report that nuclear $PIP_3$ competes with Akt to preferentially bind B23 in the nucleoplasm. Mutation of Arg23 and Arg25 in the PH domain of Akt prevents binding to $PIP_3$, but does not disrupt the Akt/B23 interaction. However, treatment with phosphatases PTEN or SHIP abrogates the association between Akt and B23, indicating that nuclear $PIP_3$ regulates the Akt/B23 interaction by controlling the concentration and subcellular dynamics of these two proteins.

• Journal of Gastric Cancer
• /
• 제3권2호
• /
• pp.88-92
• /
• 2003

Purpose: Mounting evidence suggests that alterations of Akt/protein kinase B (PKB) play an important role in tumorigenesis. Phosphorylated Akt regulates many of the key effector molecules involved in apoptosis, angiogenesis, and cell-cycle progression during tumorigenesis. The expression of phosphorylated Akt has been described in some human malignancies, but not in primary human gastric cancer. The purpose of this study was to explore the expression status of phosphorylated Akt protein in gastric carcinomas. Materials and Methods: In the current study, we analyzed the expression of phosphorylated Akt protein in 60 advanced gastric adenocarcinomas by using immunohistochemistry and a tissue microarray approach. Results: Immunopositivity (defined as $\geq\30\%$) was observed for the phosphorylated Akt in 42 ($70\%$) of the 60 cancers. Normal gastric mucosal cells showed no or weak expression of phosphorylated Akt protein. Conclusion: Taken together, these results indicate that Akt is frequently activated in gastric adenocarcinoma cells and suggest that phosphorylayed Akt may play a role in the development of human gastric adenocarcinomas.

• International Journal of Oral Biology
• /
• 제32권4호
• /
• pp.127-133
• /
• 2007

Oral squamous cell carcinoma (OSCC) is the most common malignancy and is a major cause of worldwide cancer mortality. The proto-oncogene c-myb plays an important role in regulation of cell growth and differentiation, and it is expressed at high levels in hematopoietic cells and many other types of cancers. However, the function of c-myb is not well known in OSCC. The present study aimed to reveal the function of c-myb and to test the alternation of cell growth and signaling by c-myb in OSCC. In this study, c-myb and dominant-negatibe myb(DNmyb) were expressed in an adenovirus-mediated gene delivery system to KB cells. The over-expressed c-myb brought increased cellular proliferation compared with control cells. However, DN-myb infected KB cells showed significant reduction of cell growth and enhanced induction of apoptosis to activate PARP and caspase 9. c-myb induced increase of IGF-I, -II and IGF-IR expressions while DN-myb down-regulated these expression. Activation of ERK and Akt/PKB pathway was shown only in c-myb transduced cells. These findings suggest that the role of c-myb in cell growth of oral cancer cells is partially mediated through the modulation of IGFs, ERK and Akt/PKB. From this results, DN-myb is strongly recommended as a curable gene for the treatment of c-myb dependent malignancies such as OSCC.

• Biomolecules & Therapeutics
• /
• 제24권6호
• /
• pp.589-594
• /
• 2016

Insulin is a peptide hormone of the endocrine pancreas and exerts a wide variety of physiological actions in insulin sensitive tissues, such as regulation of glucose homeostasis, cell growth, differentiation, learning and memory. However, the role of insulin in osteoblast cells remains to be fully characterized. In this study, we demonstrated that the insulin (100 nM) has the ability to stimulate the phosphorylation of protein kinase B (Akt/PKB) and extracellular signal-regulated kinase (ERK) and the levels of inhibin-${\beta}E$ in the osteoblast-like UMR-106 cells. This insulin-stimulated activities were abolished by the PI3K and MEK1 inhibitors LY294002 and PD98059, respectively. This is the first report proving that insulin is a potential candidate that enables the actions of inhibin-${\beta}E$ subunit of the TGF-${\beta}$ family. The current investigation provides a foundation for the realization of insulin as a potential stimulator in survival signaling pathways in osteoblast-like UMR-106 cells.

• 생명과학회지
• /
• 제19권8호
• /
• pp.1073-1080
• /
• 2009

비스테로이드성 항염증약(nonsteroidal anti-inflammatory drugs; NSAIDs)은 항염 및 진통효과를 나타내며, 염증억제 외에 다양한 신호전달 분자를 통해 여러 가지 세포생리활성을 조절하며, 암세포에서는 세포사멸 유도를 통한 항암제 효과를 보이고 있다. 본 연구에서는 NSAIDs가 암세포사멸프로그램을 작동시키는데 있어 phosphatidyl inositol 3-kinase (PI3K)-Akt/protein kinase B (PKB) 그리고 MEK1/2-ERK1/2 신호 전달계과 같은 anti-apoptotic program이 NSAIDs의 효과를 경감시키는 것으로 예상하고, 이들 항세포사멸 프로그램을 억제하였을 경우, NSAIDs의 세포사멸 유도작용이 증가되는지 그 가능성을 조사하였다. 세포사멸은 Hoeschst 33342으로 핵응축과 핵 쪼개짐을 염색하여 확인하였다. Western blotting을 통해 단백질 발현과 역전사중합효소연쇄반응을 통해 mRNA 발현을 확인하였다. NSAIDs 처리와 동시에 PI3K-Akt/PKB와 MEK-ERK1/2 신호전달계의 억제제를 함께 처리했을 때, NSAIDs의 세포사멸유도작용이 증가함을 확인하였다. 또한 PI3K와 MEKl/2 신호전달계의 상위에 존재하는 receptor tyrosine kinases (RTKs)의 억제제인 genistein을 함께 처리하였을 때에도 유사한 효과가 나타남을 확인하였다. 그리고 이들 복합처리에 의해 NAG-1 발현이 증가하며 NAG-1 interference 하였을 경우 복합처리에 의한 세포사멸증진 효과가 사라짐을 확인하였다. 본 연구결과는 암세포에 활성화 되어 있는 세포생존프로그램을 제어하는 물질(genistein 혹은 LY294002+U0126)을 복합처방함으로써 NSAIDs의 항암작용을 증진시킬 수 있음을 보여준다.

• Biomolecules & Therapeutics
• /
• 제29권1호
• /
• pp.90-97
• /
• 2021

Ultraviolet B (UVB) radiation causes DNA base modifications. One of these changes leads to the generation of 8-oxoguanine (8-oxoG) due to oxidative stress. In human skin, this modification may induce sunburn, inflammation, and aging and may ultimately result in cancer. We investigated whether phloroglucinol (1,3,5-trihydroxybenzene), by enhancing the expression and activity of 8-oxoG DNA glycosylase 1 (Ogg1), had an effect on the capacity of UVB-exposed human HaCaT keratinocytes to repair oxidative DNA damage. Here, the effects of phloroglucinol were investigated using a luciferase activity assay, reverse transcription-polymerase chain reactions, western blot analysis, and a chromatin immunoprecipitation assay. Phloroglucinol restored Ogg1 activity and decreased the formation of 8-oxoG in UVB-exposed cells. Moreover, phloroglucinol increased Ogg1 transcription and protein expression, counteracting the UVB-induced reduction in Ogg1 levels. Phloroglucinol also enhanced the nuclear translocation of nuclear factor erythroid 2-related factor 2 (Nrf2) as well as Nrf2 binding to an antioxidant response element located in the Ogg1 gene promoter. UVB exposure inhibited the phosphorylation of protein kinase B (PKB or Akt) and extracellular signal-regulated kinase (Erk), two major enzymes involved in cell protection against oxidative stress, regulating the activity of Nrf2. Akt and Erk phosphorylation was restored by phloroglucinol in the UVB-exposed keratinocytes. These results indicated that phloroglucinol attenuated UVB-induced 8-oxoG formation in keratinocytes via an Akt/Erk-dependent, Nrf2/Ogg1-mediated signaling pathway.