• 제목, 요약, 키워드: signaling pathway

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Mechanisms of amino acid sensing in mTOR signaling pathway

  • Kim, Eun-Jung
    • Nutrition Research and Practice
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    • v.3 no.1
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    • pp.64-71
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    • 2009
  • Amino acids are fundamental nutrients for protein synthesis and cell growth (increase in cell size). Recently, many compelling evidences have shown that the level of amino acids is sensed by extra- or intra-cellular amino acids sensor(s) and regulates protein synthesis/degradation. Mammalian target of rapamycin complex 1 (mTORC1) is placed in a central position in cell growth regulation and dysregulation of mTOR signaling pathway has been implicated in many serious human diseases including cancer, diabetes, and tissue hypertrophy. Although amino acids are the most potent activator of mTORC1, how amino acids activate mTOR signaling pathway is still largely unknown. This is partly because of the diversity of amino acids themselves including structure and metabolism. In this review, current proposed amino acid sensing mechanisms to regulate mTORC1 and the evidences pro/against the proposed models are discussed.

The Research Progress of the Interactions between miRNA and Wnt/beta-catenin Signaling Pathway in Breast Cancer of Human and Mice

  • Ye, Ni;Wang, Bin;Quan, Zi-Fang;Pan, Hai-Bo;Zhang, Man-Li;Yan, Qi-Gui
    • Asian Pacific Journal of Cancer Prevention
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    • v.15 no.3
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    • pp.1075-1079
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    • 2014
  • MicroRNA expression is a research focus in studies of tumors. This article concentrates attention on potential links between tumors caused by mouse mammary tumor virus (MMTV) and human breast cancer, in order to provide theoretical basis for using mouse model to search for miRNA effects mediated by Wnt/beta-catenin signaling in human breast cancer. By analyzing interactions between miRNAs and the Wnt/beta-catenin signaling pathway in breast cancer, we hope to casts light on more biological functions of miRNAs in the process of tumor formation and growth and to explore their potential value in cancer diagnosis, prognosis and treatment. Our endeavor aimed at providing theoretical basis for finding safer, more effective methods for treatment of human breast cancer at the miRNA molecular level.

NDRG3-mediated lactate signaling in hypoxia

  • Park, Kyung Chan;Lee, Dong Chul;Yeom, Young Il
    • BMB Reports
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    • v.48 no.6
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    • pp.301-302
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    • 2015
  • Hypoxia is associated with many pathological conditions as well as the normal physiology of metazoans. We identified a lactate-dependent signaling pathway in hypoxia, mediated by the oxygen- and lactate-regulated protein NDRG family member 3 (NDRG3). Oxygen negatively regulates NDRG3 expression at the protein level via the PHD2/VHL system, whereas lactate, produced in excess under prolonged hypoxia, blocks its proteasomal degradation by binding to NDRG3. We also found that the stabilized NDRG3 protein promotes angiogenesis and cell growth under hypoxia by activating the Raf-ERK pathway. Inhibiting cellular lactate production abolishes NDRG3-mediated hypoxia responses. The NDRG3-Raf-ERK axis therefore provides the genetic basis for lactate-induced hypoxia signaling, which can be exploited for the development of therapies targeting hypoxia-induced diseases in addition to advancing our understanding of the normal physiology of hypoxia responses. [BMB Reports 2015; 48(6): 301-302]

Curcumin Inhibits MHCC97H Liver Cancer Cells by Activating ROS/TLR-4/Caspase Signaling Pathway

  • Li, Pei-Min;Li, Yu-Liang;Liu, Bin;Wang, Wu-Jie;Wang, Yong-Zheng;Li, Zheng
    • Asian Pacific Journal of Cancer Prevention
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    • v.15 no.5
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    • pp.2329-2334
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    • 2014
  • Curcumin can inhibit proliferation of liver cancer cells by inducing apoptosis, but the specific signaling pathways involved are not completely clear. Here, we report that curcumin inhibited proliferation of MHCC97H liver cancer cells by induction of apoptosis in a concentration dependent manner via stimulating intracellular reactive oxygen species (ROS) generation. Also, we showed that increased intracellular ROS formation activated the TLR-4/MyD-88 signaling pathway, resulting in activation of caspase-8 and caspase-3, which eventually led to apoptosis in MHCC97H cells. These results showed that as an prooxidant, curcumin exerts anti-cancer effects by inducing apoptosis via the TLR-4/MyD-88 signaling pathway.

pH Response Pathways in Fungi: Adapting to Host-derived and Environmental Signals

  • Selvig, Kyla;Alspaugh, J. Andrew
    • Mycobiology
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    • v.39 no.4
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    • pp.249-256
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    • 2011
  • Microorganisms are significantly affected when the ambient pH of their environment changes. They must therefore be able to sense and respond to these changes in order to survive. Previous investigators have studied various fungal species to define conserved pH-responsive signaling pathways. One of these pathways, known as the Pal/Rim pathway, is activated in response to alkaline pH signals, ultimately targeting the PacC/Rim101 transcription factor. Although the central signaling components are conserved among divergent filamentous and yeast-like fungi, there is some degree of signaling specificity between fungal species. This specificity exists primarily in the downstream transcriptional targets of this pathway, likely allowing differential adaptation to species-specific environmental niches. In this review, the role of the Pal/Rim pathway in fungal pH response is discussed. Also highlighted are functional differences present in this pathway among human fungal pathogens, differences that allow these specialized microorganisms to survive in the various micro-environments of the infected human host.

Methanol Extract of Cinnamomum cassia Represses Cellular Proliferation and Gli-mediated Transcription in PANC-1 Human Pancreatic Cancer Cells

  • Lee, Hwa Jin
    • Natural Product Sciences
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    • v.20 no.3
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    • pp.170-175
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    • 2014
  • Twenty five methanolic plant extracts were investigated to determine the anticancer activity against sonic hedgehog (shh)/Gli signaling pathway dependent cancer, PANC-1 human pancreatic cancer cells, through three screening programs. All extracts were inspected their inhibitory properties on sonic hedgehog-conditioned medium (shh-CM) induced alkaline phosphatase (ALP) activity in C3H10T1/2 mouse mesenchymal stem cells to examine whether the plant extracts affect the shh/Gli signaling pathway. Next, plant extracts were screened the ability to suppress the cell proliferation of PANC-1 human pancreatic cancer cells. Finally, active plant extracts from the two screening systems were evaluated for the suppressive effect on Gli-mediated transcriptional activity in PANC-1 cells. Among active plants, Cinnamomum cassia suppressed Gli-mediated transcriptional activity leading to the down-regulated expression of Gli-target genes such as Gli-1 and Patched-1 (Ptch-1). This study provides the consideration for the important role of natural products in drug discovery process as well as the basis for the further analysis of active plant and potential identification of novel bioactive compounds as inhibitors of Gli and therapeutic candidates against shh/Gli signaling pathway dependent cancers.

Upstream paths for Hippo signaling in Drosophila organ development

  • Choi, Kwang-Wook
    • BMB Reports
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    • v.51 no.3
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    • pp.134-142
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    • 2018
  • Organ growth is fundamental to animal development. One of major mechanisms for growth control is mediated by the conserved Hippo signaling pathway initially identified in Drosophila. The core of this pathway in Drosophila consists of a cascade of protein kinases Hippo and Warts that negatively regulate transcriptional coactivator Yorkie (Yki). Activation of Yki promotes cell survival and proliferation to induce organ growth. A key issue in Hippo signaling is to understand how core kinase cascade is activated. Activation of Hippo kinase cascade is regulated in the upstream by at least two transmembrane proteins Crumbs and Fat that act in parallel. These membrane proteins interact with additional factors such as FERM-domain proteins Expanded and Merlin to modulate subcellular localization and function of the Hippo kinase cascade. Hippo signaling is also influenced by cytoskeletal networks and cell tension in epithelia of developing organs. These upstream events in the regulation of Hippo signaling are only partially understood. This review focuses on our current understanding of some upstream processes involved in Hippo signaling in developing Drosophila organs.

The Stress-Activated Signaling (SAS) Pathways of a Human Fungal Pathogen, Cryptococcus neoformans

  • Jung, Kwang-Woo;Bahn, Yong-Sun
    • Mycobiology
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    • v.37 no.3
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    • pp.161-170
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    • 2009
  • Cryptococcus neoformans is a basidiomycete human fungal pathogen that causes meningoencephalitis in both immunocompromised and immunocompetent individuals. The ability to sense and respond to diverse extracellular signals is essential for the pathogen to infect and cause disease in the host. Four major stress-activated signaling (SAS) pathways have been characterized in C. neoformans, including the HOG (high osmolarity glycerol response), PKC/Mpk1 MAPK (mitogen-activated protein kinase), calcium-dependent calcineurin, and RAS signaling pathways. The HOG pathway in C. neoformans not only controls responses to diverse environmental stresses, including osmotic shock, UV irradiation, oxidative stress, heavy metal stress, antifungal drugs, toxic metabolites, and high temperature, but also regulates ergosterol biosynthesis. The PKC(protein kinase C)/Mpk1 pathway in C. neoformans is involved in a variety of stress responses, including osmotic, oxidative, and nitrosative stresses and breaches of cell wall integrity. The $Ca^{2+}$/calmodulin- and Ras-signaling pathways also play critical roles in adaptation to certain environmental stresses, such as high temperature and sexual differentiation. Perturbation of the SAS pathways not only impairs the ability of C. neoformans to resist a variety of environmental stresses during host infection, but also affects production of virulence factors, such as capsule and melanin. A drug(s) capable of targeting signaling components of the SAS pathway will be effective for treatment of cryptococcosis.

Effect of the hedgehog signaling pathway on hair formation-related cells

  • Park, Jaehyun;Park, Sangkyu;Seo, Jeongmin;Roh, Sangho
    • International Journal of Oral Biology
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    • v.44 no.4
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    • pp.144-151
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    • 2019
  • Alopecia has emerged as one of the biggest interests in modern society. Many studies have focused on the treatment of alopecia, such as transplantation of hair follicles or inhibition of the androgen pathway. Hair growth is achieved through proper proliferation of the components such as keratinocytes and dermal papilla cells (DPCs), movement, and interaction between the two cells. The present study examined the effect of the hedgehog (Hh) signaling pathway, which is an important and fundamental signal in the cell, on the morphology and the viability of human keratinocytes and DPCs. Upregulation of Hh signaling caused a morphological change and an increase in epithelium-mesenchymal transition-related gene expression but reduced the viability of keratinocytes, while the alteration of Hh signaling did not cause any change in DPCs. The results show the possibility that the regulation of Hh signaling can be applied for the treatment of alopecia.

KSP inhibitor SB743921 induces death of multiple myeloma cells via inhibition of the NF-κB signaling pathway

  • Song, In-Sung;Jeong, Yu Jeong;Nyamaa, Bayalagmaa;Jeong, Seung Hun;Kim, Hyoung Kyu;Kim, Nari;Ko, Kyung Soo;Rhee, Byoung Doo;Han, Jin
    • BMB Reports
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    • v.48 no.10
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    • pp.571-576
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    • 2015
  • SB743921 is a potent inhibitor of the spindle protein kinesin and is being investigated in ongoing clinical trials for the treatment of myeloma. However, little is known about the molecular events underlying the induction of cell death in multiple myeloma (MM) by SB743921, alone or in combination treatment. Here, we report that SB743921 induces mitochondria-mediated cell death via inhibition of the $NF-{\kappa}B$ signaling pathway, but does not cause cell cycle arrest in KMS20 MM cells. SB743921-mediated inhibition of the $NF-{\kappa}B$ pathway results in reduced expression of SOD2 and Mcl-1, leading to mitochondrial dysfunction. We also found that combination treatment with SB743921 and bortezomib induces death in bortezomib-resistant KMS20 cells. Altogether, these data suggest that treatment with SB743921 alone or in combination with bortezomib offers excellent translational potential and promises to be a novel MM therapy.