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Martin Sztacho, Sandra Segeletz, Maria Arantzazu Sanchez-Fernandez, Cornelia Czupalla, Christian Niehage, Bernard Hoflack
Bone resorption in vertebrates relies on the ability of osteoclasts to assemble F-actin-rich podosomes that condense into podosomal belts, forming sealing zones. Sealing zones segregate bone-facing ruffled membranes from other membrane domains, and disassemble when osteoclasts migrate to new areas. How podosome/sealing zone dynamics is regulated remains unknown. We illustrate the essential role of the membrane scaffolding F-BAR-Proline-Serine-Threonine Phosphatase Interacting Proteins (PSTPIP) 1 and 2 in this process...
2016: PloS One
Elmer Hoekstra, Asha M Das, Marcella Willemsen, Marloes Swets, Peter J K Kuppen, Christien J van der Woude, Marco J Bruno, Jigisha P Shah, Timo L M Ten Hagen, John D Chisholm, William G Kerr, Maikel P Peppelenbosch, Gwenny M Fuhler
Colorectal cancer (CRC) is the second most common cause of cancer-related death, encouraging the search for novel therapeutic targets affecting tumor cell proliferation and migration. These cellular processes are under tight control of two opposing groups of enzymes; kinases and phosphatases. Aberrant activity of kinases is observed in many forms of cancer and as phosphatases counteract such "oncogenic" kinases, it is generally assumed that phosphatases function as tumor suppressors. However, emerging evidence suggests that the lipid phosphatase SH2-domain-containing 5 inositol phosphatase (SHIP2), encoded by the INPPL1 gene, may act as an oncogene...
September 28, 2016: Oncotarget
Kristen E Rennoll-Bankert, M Sayeedur Rahman, Mark L Guillotte, Stephanie S Lehman, Magda Beier-Sexton, Joseph J Gillespie, Abdu F Azad
Rickettsiae are obligate intracellular pathogens that induce their uptake into non-phagocytic cells; however, the events instigating this process are incompletely understood. Importantly, diverse Rickettsia species are predicted to utilize divergent mechanisms to colonize host cells, as nearly all adhesins and effectors involved in host cell entry are differentially encoded in diverse Rickettsia species. One particular effector, RalF, a sec-7 domain containing protein that functions as a guanine nucleotide exchange factor of ADP-ribosylation factors (Arfs), is critical for R...
October 3, 2016: Infection and Immunity
Huahua Yin, Yan Tan, Xiaofeng Wu, Hong Yan, Feng Liu, Yuanzhang Yao, Jianxin Jiang, Qi Wan, Lei Li
In this study, we explored the potential mechanisms of how PTEN regulating LPS induced TLR4 signaling pathway. The initial findings from ELISA demonstrate that PTEN influences TNF-α secretion by its lipid phosphatase activity. Subsequently, western blot, immunoprecipitation assay, and immunofluorescence were performed to explore the activation process of PTEN by stimulation with LPS. As early as 20 minutes after LPS stimulation, reduced phosphorylation of PTEN was found obviously. Accordingly, the whole cell-scattered PTEN translocated towards the cell membrane 20 minutes after stimulating with LPS...
2016: BioMed Research International
Wenyan Xu, Miaomiao Jin, Ruikun Hu, Hong Wang, Fan Zhang, Shiaulou Yuan, Ying Cao
Phosphoinositides, a family of phosphorylated derivatives of phosphatidylinositol (PtdIns), are tightly regulated both temporally and spatially by PtdIns phosphatases and kinases. Mutations in inositol polyphosphate 5-phosphatase E (INPP5E) cause Joubert syndrome, a human disorder associated with numerous ciliopathic defects, including renal cyst formation, linking phosphoinositides to ciliopathies. However, the molecular mechanism by which INPP5E-mediated PtdIns signaling regulates ciliogenesis and cystogenesis is unclear...
July 8, 2016: Journal of the American Society of Nephrology: JASN
Satomi Matsuoka, Yukihiro Miyanaga, Masahiro Ueda
The chemotactic signaling of eukaryotic cells is based on a chain of interactions between signaling molecules diffusing on the cell membrane and those shuttling between the membrane and cytoplasm. In this chapter, we describe methods to quantify lateral diffusion and reaction kinetics on the cell membrane. By the direct visualization and statistic analyses of molecular Brownian movement achieved by single-molecule imaging techniques, multiple states of membrane-bound molecules are successfully revealed with state transition kinetics...
2016: Methods in Molecular Biology
Dongil Keum, Martin Kruse, Dong-Il Kim, Bertil Hille, Byung-Chang Suh
Voltage-sensing phosphatases (VSPs) are homologs of phosphatase and tensin homolog (PTEN), a phosphatidylinositol 3,4-bisphosphate [PI(3,4)P2] and phosphatidylinositol 3,4,5-trisphosphate [PI(3,4,5)P3] 3-phosphatase. However, VSPs have a wider range of substrates, cleaving 3-phosphate from PI(3,4)P2 and probably PI(3,4,5)P3 as well as 5-phosphate from phosphatidylinositol 4,5-bisphosphate [PI(4,5)P2] and PI(3,4,5)P3 in response to membrane depolarization. Recent proposals say these reactions have differing voltage dependence...
June 28, 2016: Proceedings of the National Academy of Sciences of the United States of America
Johanne Le Coq, Luis Heredia Gallego, Daniel Lietha
The Src homology 2 containing inositol 5-phosphatase 2 (SHIP2) catalyses the dephosphorylation of the phospholipid phosphatidylinositol 3,4,5-triphosphate (PI(3,4,5)P3) to form PI(3,4)P2. PI(3,4,5)P3 is a key lipid second messenger, which can recruit signalling proteins to the plasma membrane and subsequently initiate numerous downstream signalling pathways responsible for the regulation of a plethora of cellular events such as proliferation, growth, apoptosis and cytoskeletal rearrangements. SHIP2 has been heavily implicated with several serious diseases such as cancer and type 2 diabetes but its regulation remains poorly understood...
June 2016: Protein Journal
Yingke Xu, Di Nan, Jiannan Fan, Jonathan S Bogan, Derek Toomre
Glucose transporter 4 (GLUT4; also known as SLC2A4) resides on intracellular vesicles in muscle and adipose cells, and translocates to the plasma membrane in response to insulin. The phosphoinositide 3-kinase (PI3K)-Akt signaling pathway plays a major role in GLUT4 translocation; however, a challenge has been to unravel the potentially distinct contributions of PI3K and Akt (of which there are three isoforms, Akt1-Akt3) to overall insulin action. Here, we describe new optogenetic tools based on CRY2 and the N-terminus of CIB1 (CIBN)...
May 15, 2016: Journal of Cell Science
Wassim Daher, Juliette Morlon-Guyot, Tchilabalo Dilezitoko Alayi, Stan Tomavo, Kai Wengelnik, Maryse Lebrun
The phosphoinositide phosphatidylinositol-3,5-bisphosphate (PI(3,5)P2) plays crucial roles in the maintenance of lysosome/vacuole morphology, membrane trafficking and regulation of endolysosome-localized membrane channel activity. In Toxoplasma gondii, we previously reported that PI(3,5)P2 is essential for parasite survival by controlling homeostasis of the apicoplast, a particular organelle of algal origin. Here, by using a phosphoinositide pull-down assay, we identified TgPH1 in Toxoplasma a protein conserved in many apicomplexan parasites...
May 2016: Molecular and Biochemical Parasitology
Anabel Gil, José I López, Rafael Pulido
PTEN subcellular localization is fundamental in the execution of the distinct PTEN biological activities, including not only its PI(3,4,5)P3 phosphatase activity when associated to membranes but also its subcellular compartment-specific interactions with regulatory and effector proteins, including those exerted in the nucleus. As a consequence, PTEN subcellular localization is tightly regulated in vivo by both intrinsic and extrinsic mechanisms. The plasma membrane/nucleus/cytoplasm partitioning of PTEN has been the focus of several studies, both from a mechanistic and from a disease-association point of view...
2016: Methods in Molecular Biology
Jia Lin, Svetlana Kurilova, Brandon L Scott, Elizabeth Bosworth, Bradley E Iverson, Elizabeth M Bailey, Adam D Hoppe
BACKGROUND: Recent evidence indicates that in addition to the T-cell receptor, microclustering is an important mechanism for the activation of the B-cell receptor and the mast cell Fcε-receptor. In macrophages and neutrophils, particles opsonized with immunoglobulin G (IgG) antibodies activate the phagocytic Fcγ-receptor (FcγR) leading to rearrangements of the actin cytoskeleton. The purpose of this study was to establish a system for high-resolution imaging of FcγR microclustering dynamics and the recruitment of the downstream signaling machinery to these microclusters...
2016: BMC Immunology
Christophe Erneux, Somadri Ghosh, Ana Raquel Ramos, William's Elong Edimo
Inositol polyphosphate 5-phosphatases act on inositol phosphates and phosphoinositides as substrates. They are 10 different isoenzymes and several splice variants in the human genome that are involved in a series of human pathologies such as the Lowe syndrome, the Joubert and MORM syndromes, breast cancer, glioblastoma, gastric cancer and several other type of cancers. Inositol 5-phosphatases can be amplified in human cancer cells, whereas the 3- and 4- phosphatase tumor suppressor PTEN and INPP4B, repectively are often repressed or deleted...
2016: Current Pharmaceutical Design
Phillip T Hawkins, Len R Stephens
There are eight members of the phosphoinositide family of phospholipids in eukaryotes; PI, PI3P, PI4P, PI5P, PI(4,5)P2, PI(3,4)P2, PI(3,5)P2 and PI(3,4,5)P3. Receptor activation of Class I PI3Ks stimulates the phosphorylation of PI(4,5)P2 to form PI(3,4,5)P3. PI(3,4,5)P3 is an important messenger molecule that is part of a complex signalling network controlling cell growth and division. PI(3,4,5)P3 can be dephosphorylated by both 3- and 5-phosphatases, producing PI(4,5)P2 and PI(3,4)P2, respectively. There is now strong evidence that PI(3,4)P2 generated by this route does not merely represent another pathway for removal of PI(3,4,5)P3, but can act as a signalling molecule in its own right, regulating macropinocytosis, fast endophilin-mediated endocytosis (FEME), membrane ruffling, lamellipodia and invadopodia...
February 2016: Biochemical Society Transactions
Elena P Sablin, Raymond D Blind, Rubatharshini Uthayaruban, Hsiu-Ju Chiu, Ashley M Deacon, Debanu Das, Holly A Ingraham, Robert J Fletterick
The nuclear receptor LRH-1 (Liver Receptor Homolog-1, NR5A2) is a transcription factor that regulates gene expression programs critical for many aspects of metabolism and reproduction. Although LRH-1 is able to bind phospholipids, it is still considered an orphan nuclear receptor (NR) with an unknown regulatory hormone. Our prior cellular and structural studies demonstrated that the signaling phosphatidylinositols PI(4,5)P2 (PIP2) and PI(3,4,5)P3 (PIP3) bind and regulate SF-1 (Steroidogenic Factor-1, NR5A1), a close homolog of LRH-1...
December 2015: Journal of Structural Biology
Angeliki Mavrantoni, Veronika Thallmair, Michael G Leitner, Daniela N Schreiber, Dominik Oliver, Christian R Halaszovich
Voltage sensitive phosphatases (VSPs), including engineered voltage sensitive PTEN, are excellent tools to rapidly and reversibly alter the phosphoinositide (PI) content of the plasma membrane in vivo and study the tumor suppressor PTEN. However, widespread adoption of these tools is hampered by the requirement for electrophysiological instrumentation to control the activity of VSPs. Additionally, monitoring and quantifying the PI changes in living cells requires sophisticated microscopy equipment and image analysis...
2015: Frontiers in Pharmacology
Y-M Hao, Q-J Liu, R-Y Wang, Y-P Cao, Y Zhang, L-F Zuo
OBJECTIVE: Type 2 diabetes mellitus (T2DM) is a chronic disease characterized by insulin resistance in the target tissue of insulin with insufficient insulin secretion in pancreatic β-cells. Src homology 2-containing 5'-inositol phosphatase 2 (SHIP2) is a lipid phosphatase that hydrolyzes PI3-kinase product PI(3,4,5)P3 to PI(3,4)P2, which contributes to the negative regulation of insulin signaling both in vitro and in vivo. Some polymorphisms of SHIP2 have been reported to be associated with the metabolic syndrome including T2DM and hypertension in British, French and Japanese T2DM population...
January 2015: European Review for Medical and Pharmacological Sciences
Nie Tian, Takeshi Kanno, Yu Jin, Tomoyuki Nishizaki
Accumulating evidence has pointed to the direct inhibitory action of lithium, an anti-depressant, on GSK-3β. The present study investigated further insight into lithium signaling pathways. In the cell-free assay Li2CO3 significantly inhibited phosphoinositide 3-kinase (PI3K)-mediated phosphorylation of Akt1 at Ser473, but Li2CO3 did not affect PI3K-mediated PI(3,4,5)P3 production and 3-phosphoinositide-dependent protein kinase 1 (PDK1)-mediated phosphorylation of Akt1 at Thr308. This indicates that lithium could enhance GSK-3β activity by suppressing Akt-mediated Ser9 phosphorylation of GSK-3β in association with inhibition of PI3K-mediated Akt activation...
July 18, 2014: Biochemical and Biophysical Research Communications
Laura Marie Plum, Anne Brieger, Gabriela Engelhardt, Silke Hebel, Andreas Nessel, Marcus Arlt, Jennifer Kaltenberg, Ulrich Schwaneberg, Michael Huber, Lothar Rink, Hajo Haase
Free zinc ions (Zn(2+)) participate in several signaling pathways. The aim of the present study was to investigate a potential involvement of Zn(2+) in the PI3K/Akt pathway of interleukin (IL)-2 signaling in T-cells. The IL-2 receptor triggers three major pathways, ERK1/2, JAK/STAT5, and PI3K/Akt. We have previously shown that an IL-2-mediated release of lysosomal Zn(2+) into the cytoplasm activates ERK1/2, but not STAT5. In the present study, Akt phosphorylation in response to IL-2 was abrogated by the Zn(2+) chelator N,N,N',N'-tetrakis-2(pyridyl-methyl)ethylenediamine, and was induced by treatment with Zn(2+) and the ionophore pyrithione...
July 2014: Metallomics: Integrated Biometal Science
Patricia Kreis, George Leondaritis, Ivo Lieberam, Britta J Eickholt
PTEN is a lipid and protein phosphatase that regulates a diverse range of cellular mechanisms. PTEN is mainly present in the cytosol and transiently associates with the plasma membrane to dephosphorylate PI(3,4,5)P3, thereby antagonizing the PI3-Kinase signaling pathway. Recently, PTEN has been shown to associate also with organelles such as the endoplasmic reticulum (ER), the mitochondria, or the nucleus, and to be secreted outside of the cell. In addition, PTEN dynamically localizes to specialized sub-cellular compartments such as the neuronal growth cone or dendritic spines...
2014: Frontiers in Molecular Neuroscience
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