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Samual C Allgood, Barbara P Romero Dueñas, Rebecca R Noll, Colleen Pike, Sean Lein, M Ramona Neunuebel
The facultative intracellular bacterium Legionella pneumophila proliferates within amoebae and human alveolar macrophages, and it is the causative agent of Legionnaires' disease, a life-threatening pneumonia. Within host cells, L. pneumophila establishes a replicative haven by delivering numerous effector proteins into the host cytosol, many of which target membrane trafficking by manipulating the function of Rab GTPases. The Legionella effector AnkX is a phosphocholine transferase that covalently modifies host Rab1 and Rab35...
2017: Frontiers in Cellular and Infection Microbiology
Q Qi, S S Kang, S Zhang, C Pham, H Fu, D J Brat, K Ye
Glioblastoma (GBM) is the most common primary brain tumor and has a dismal prognosis. Amplification of chromosome 12q13-q15 (Cyclin-dependent kinase 4 (CDK4) amplicon) is frequently observed in numerous human cancers including GBM. Phosphoinositide 3-kinase enhancer (PIKE) is a group of GTP-binding proteins that belong to the subgroup of centaurin GTPase family, encoded by CENTG1 located in CDK4 amplicon. However, the pathological significance of CDK4 amplicon in GBM formation remains incompletely understood...
August 10, 2017: Oncogene
Anna Lisa Gündner, Ines Hahn, Oliver Sendscheid, Hermann Aberle, Michael Hoch
Phosphoinositide-3-kinase enhancer (PIKE) proteins encoded by the PIKE/CENTG1 gene are members of the gamma subgroup of the Centaurin superfamily of small GTPases. They are characterized by their chimeric protein domain architecture consisting of a pleckstrin homology (PH) domain, a GTPase-activating (GAP) domain, Ankyrin repeats as well as an intrinsic GTPase domain. In mammals, three PIKE isoforms with variations in protein structure and subcellular localization are encoded by the PIKE locus. PIKE inactivation in mice results in a broad range of defects, including neuronal cell death during brain development and misregulation of mammary gland development...
2014: PloS One
Qi Qi, Keqiang Ye
Tumorigenesis is the process by which normal cells evolve the capacity to evade and overcome the constraints usually placed upon their growth and survival. To ensure the integrity of organs and tissues, the balance of cell proliferation and cell death is tightly maintained. The proteins controlling this balance are either considered oncogenes, which promote tumorigenesis, or tumor suppressors, which prevent tumorigenesis. Phosphoinositide 3-kinase enhancer (PIKE) is a family of GTP-binding proteins that possess anti-apoptotic functions and play an important role in the central nervous system...
August 2013: Acta Pharmacologica Sinica
Margaret Chui Ling Tse, Xia Liu, Seran Yang, Keqiang Ye, Chi Bun Chan
Fyn is a tyrosine kinase with multiple roles in a variety of cellular processes. Here we report that Fyn is a new kinase involved in adipocyte differentiation. Elevated Fyn protein is detected specifically in the adipocytes of obese mice. Moreover, Fyn expression increases progressively in 3T3-L1 cells during in vitro adipogenesis, which correlates with its kinase activity. Inhibition of Fyn by either genetic or pharmacological manipulation restrains the 3T3-L1 preadipocytes from fully differentiating into mature adipocytes...
May 2013: Molecular and Cellular Biology
Chi Bun Chan, Keqiang Ye
Since its discovery in 2000, phosphoinositide 3-kinase enhancer (PIKE) has been recognized as a class of GTPase that controls the enzymatic activities of phosphoinositide 3-kinase (PI3K) and Akt in the central nervous system (CNS). However, recent studies suggest that PIKEs are not only enhancers to PI3K/Akt but also modulators to other kinases including insulin receptor tyrosine kinase and focal adhesion kinases. Moreover, they regulate transcription factors such as signal transducer and activator of transcription and nuclear factor κB...
2012: Reviews in the Neurosciences
Q Qi, K He, X Liu, C Pham, C Meyerkord, H Fu, K Ye
The cyclin-dependent kinase 4 (CDK4) amplicon is frequently amplified in numerous human cancers including gliomas. PIKE-A, a proto-oncogene that is one of the important components of the CDK4 amplicon, binds to and enhances the kinase activity of Akt, thereby promoting cancer progression. To define the roles of the PIKE-A/Akt interaction in glioblastoma multiform (GBM) progression, we used biochemical protein/protein interaction (PPI) assays and live cell fluorescence-based protein complementation assays to search for small peptide antagonist from these proteins that were able to block their interaction...
February 21, 2013: Oncogene
Z Xie, Y Jiang, E-Y Liao, Y Chen, S D Pennypacker, J Peng, S M Chang
One of the key drivers for squamous cell carcinoma (SCC) proliferation is activation of the epidermal growth factor receptor (EGFR), a known proto-oncogene. However, the mechanism of EGFR-dependent SCC proliferation remains unclear. Our previous studies indicate that epidermal growth factor (EGF)-induced SCC cell proliferation requires the SH3 domain of phospholipase C-γ1 (PLC-γ1), but not its catalytic activity. The SH3 domain of PLC-γ1 is known to activate the short form of nuclear phosphatidylinositol 3-kinase enhancer (PIKE) that enhances the activity of nuclear class Ia phosphatidylinositol 3-kinase (PI3K) required for proliferation...
December 6, 2012: Oncogene
Chi Bun Chan, Keqiang Ye
Phosphoinositide 3-kinase enhancer (PIKE) is a group of GTPase that belongs to the centaurin superfamily. These proteins have been discovered for more than a decade but our understandings on their functions are still limited. Studies from our research group and others have revealed some of their functions in a cellular context but their roles in organ development or systemic homeostasis just begin to unveil. The generation of PIKE knockout mice thus provides the valuable model to delineate the physiological roles of PIKE...
2011: International Journal of Biochemistry and Molecular Biology
Chi Bun Chan, Yongjun Chen, Xia Liu, Ligia Papale, Andrew Escayg, Lin Mei, Keqiang Ye
No abstract text is available yet for this article.
January 2012: Advances in Biological Regulation
Chi Bun Chan, Yongjun Chen, Xia Liu, Xiaoling Tang, Chi Wai Lee, Lin Mei, Keqiang Ye
AMPAR (α-amino-3-hydroxy-5-methyl-isoxazole-4-propionic acid receptor) is an ion channel involved in the formation of synaptic plasticity. However, the molecular mechanism that couples plasticity stimuli to the trafficking of postsynaptic AMPAR remains poorly understood. Here, we show that PIKE (phosphoinositide 3-kinase enhancer) GTPases regulate neuronal AMPAR activity by promoting GluA2/GRIP1 association. PIKE-L directly interacts with both GluA2 and GRIP1 and forms a tertiary complex upon glycine-induced NMDA receptor activation...
October 19, 2011: EMBO Journal
Kunyan He, Sung-Wuk Jang, Jayashree Joshi, Min-Heui Yoo, Keqiang Ye
UNC5B acts as a tumor suppressor, and it induces apoptosis in the absence of its cognate ligand netrins. UNC5B is a direct transcriptional target of p53 upon UV stimulation. Here we show that Akt phosphorylates PIKE-A and regulates its association with UNC5B and inhibits UNC5B-provoked apoptosis in a p53-dependent manner. PIKE-A GTPase binds active Akt and stimulates its kinase activity in a guanine-nucleotide-dependent way. Akt feeds back and phosphorylates PIKE-A on Ser-472 and subsequently enhances its stimulatory effect on Akt kinase activity...
June 1, 2011: Molecular Biology of the Cell
Chi Bun Chan, Keqiang Ye
GTP-binding proteins are the molecular switches of numerous cellular functions, including migration, proliferation, and differentiation. In the past 10 years, we have characterized a novel class of GTPases called phosphoinositide-3 kinase enhancer (PIKE) that interacts with PI3K/Akt. In neurons, PIKE is involved in the protective mechanisms against neuroexcitotoxic insults by linking various receptors, such as mGluR1 and Unc5H2, to the PI3K cascade. Interestingly, the PIKE gene (CENTG1) is also amplified in a variety of human cancers and enhances Akt activity, leading to their resistance against apoptosis and invasion...
April 13, 2010: TheScientificWorldJournal
Keqiang Ye
The neurofibromatosis-2 (NF2) tumor suppressor protein, merlin or schwannomin, inhibits cell proliferation by modulating the growth activities of its binding partners, including the cell surface glycoprotein CD44, membrane-cytoskeleton linker protein ezrin and PIKE (PI 3-kinase enhancer) GTPase, etc. Merlin exerts its growth suppressive activity through a folded conformation that is tightly controlled through phosphorylation by numerous protein kinases including PAK, PKA and Akt. Merlin inhibits PI 3-kinase activity through binding to PIKE-L...
October 2007: Cell Adhesion & Migration
Yi Cai, Jianghua Wang, Rile Li, Gustavo Ayala, Michael Ittmann, Mingyao Liu
GGAP2/PIKE-A is a GTP-binding protein that can enhance Akt activity. Increased activation of the AKT and nuclear factor-kappaB (NF-kappaB) pathways have been identified as critical steps in cancer initiation and progression in a variety of human cancers. We have found significantly increased expression GGAP2 in the majority of human prostate cancers and GGAP2 expression increases Akt activation in prostate cancer cells. Thus, increased GGAP2 expression is a common mechanism for enhancing the activity of the Akt pathway in prostate cancers...
February 1, 2009: Cancer Research
Ren Liu, Bo Tian, Marla Gearing, Stephen Hunter, Keqiang Ye, Zixu Mao
Isoform A of phosphatidylinositol 3-kinase enhancer (PIKE-A) is a newly identified prooncogenic factor that has been implicated in cancer cell growth. How PIKE-A activity is regulated in response to growth signal is poorly understood. Here, we demonstrate that cyclin dependent kinase 5 (Cdk5), a protein known to function mainly in postmitotic neurons, directly phosphorylates PIKE-A at Ser-279 in its GTPase domain in glioblastoma cells. This phosphorylation event stimulates PIKE-A GTPase activity and the activity of its downstream effector Akt...
May 27, 2008: Proceedings of the National Academy of Sciences of the United States of America
Xiaoling Tang, Sung-Wuk Jang, Masashi Okada, Chi-Bun Chan, Yue Feng, Yu Liu, Shi-Wen Luo, Yan Hong, Nicolas Rama, Wen-Cheng Xiong, Patrick Mehlen, Keqiang Ye
Netrins, a family of secreted molecules, have critical functions in axon guidance and cell migration during neuronal development. In addition to its role as a chemotropic molecule, netrin-1 also acts as a survival factor. Both UNC5 (that is, UNC5A, UNC5B, UNC5C or UNC5D) and DCC are transmembrane receptors for netrin-1 (Refs 8, 9). In the absence of netrin-1, DCC and UNC5 act as dependence receptors and trigger apoptosis. However, how netrin-1 suppresses the apoptotic activity of the receptors remains elusive...
June 2008: Nature Cell Biology
Zhixue Liu, Sung-Wuk Jang, Xia Liu, Dongmei Cheng, Junmin Peng, Manuel Yepes, Xiao-jiang Li, Steve Matthews, Colin Watts, Masahide Asano, Ikuko Hara-Nishimura, Hongbo R Luo, Keqiang Ye
Ischemia and seizure cause excessive neuronal excitation that is associated with brain acidosis and neuronal cell death. However, the molecular mechanism of acidification-triggered neuronal injury is incompletely understood. Here, we show that asparagine endopeptidase (AEP) is activated under acidic condition, cuts SET, an inhibitor of DNase, and triggers DNA damage in brain, which is inhibited by PIKE-L. SET, a substrate of caspases, was cleaved by acidic cytosolic extract independent of caspase activation...
March 28, 2008: Molecular Cell
Jing Yan, Wenyu Wen, Ling-Nga Chan, Mingjie Zhang
Cytoplasm-nucleus shuttling of phosphoinositol 3-kinase enhancer (PIKE) is known to correlate directly with its cellular functions. However, the molecular mechanism governing this shuttling is not known. In this work, we demonstrate that PIKE is a new member of split pleckstrin homology (PH) domain-containing proteins. The structure solved in this work reveals that the PIKE PH domain is split into halves by a positively charged nuclear localization sequence. The PIKE PH domain binds to the head groups of di- and triphosphoinositides with similar affinities...
April 25, 2008: Journal of Molecular Biology
Daniel R Scoles
The neurofibromatosis 2 (NF2) tumor suppressor protein merlin is commonly mutated in human benign brain tumors. The gene altered in NF2 was located on human chromosome 22q12 in 1993 and the encoded protein named merlin and schwannomin. Merlin has homology to ERM family proteins, ezrin, radixin, and moesin, within the protein 4.1 superfamily. In efforts to determine merlin function several groups have discovered 34 merlin interacting proteins, including ezrin, radixin, moesin, CD44, layilin, paxillin, actin, N-WASP, betaII-spectrin, microtubules, TRBP, eIF3c, PIKE, NHERF, MAP, RalGDS, RhoGDI, EG1/magicin, HEI10, HRS, syntenin, caspr/paranodin, DCC, NGB, CRM1/exportin, SCHIP1, MYPT-1-PP1delta, RIbeta, PKA, PAK (three types), calpain and Drosophila expanded...
January 2008: Biochimica et Biophysica Acta
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