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Current Topics in Microbiology and... 2010The phosphoinositide-3-kinase (PI3K) family of lipid kinases has been well conserved from yeast to mammals. In this evolutionary perspective on the PI3K family, we...
The phosphoinositide-3-kinase (PI3K) family of lipid kinases has been well conserved from yeast to mammals. In this evolutionary perspective on the PI3K family, we discuss the prototypical properties of PI3Ks: 1) the utilization of sparse but specifically localized lipid substrates; 2) the nucleation signaling complexes at membrane-targeted sites; and 3) the integration of intracellular signaling with extracellular cues. Together, these three core properties serve to establish order within the entropic environment of the cell. Many human diseases, including cancer and diabetes, are the direct result of loss or defects in one or more of these core properties, putting much hope in the clinical use of PI3K inhibitors singly and in combination to restore order within diseased tissues.
Topics: Animals; Humans; Phosphatidylinositol 3-Kinases; Phosphatidylinositols
PubMed: 20582535
DOI: 10.1007/82_2010_55 -
Journal of Chromatography. A Jan 2021Phosphatidylinositols (PIs) constitute a minor class of phospholipid with wide-spread influence throughout various cellular functions. Monitoring the distribution of...
Phosphatidylinositols (PIs) constitute a minor class of phospholipid with wide-spread influence throughout various cellular functions. Monitoring the distribution of these lipids can therefore provide insight as to the state of cellular processes or reveal the development of various pathologies. The speciation of these compounds is often performed either as part of a comprehensive characterisation of lipids, or specifically targeted using the same methods, however, such methods were intended to maximise coverage of lipid classes rather than provide an in-depth analysis of any single class. In the particular case of PIs, the majority of reported molecular diversity is limited to a small proportion of the already minor class, as such the cursory glance enabled by such methods is insufficient. Therefore, this work compared the suitability of both established and novel LC-MS buffers with the aim of maximising the ionisation efficiency of PIs, in an attempt to enhance coverage of the class. Through experimentation, it was determined that a 0.25 mM ammonium fluoride buffer provided up to a 6-fold increase in signal intensity, and on average a 38-fold increase in the signal-to-noise ratio. Using these new conditions, 14 PI species, and 12 PI candidates were identified within a dilute lipid extract sourced from canola seed, compared to 0 species identified using the generalised method. As a result, it is suggested that this procedure has yielded the highest number of PI species identifications for a sample of this concentration. Methods which therefore intend to characterise PI species in dilute quantities, such as those extracted from mammalian cells, are henceforth provided with the means to conduct more comprehensive characterisations.
Topics: Animals; Buffers; Chromatography, Liquid; Mass Spectrometry; Phosphatidylinositols; Signal-To-Noise Ratio
PubMed: 33422796
DOI: 10.1016/j.chroma.2020.461860 -
Cellular Physiology and Biochemistry :... 2014The present study was conducted to understand biochemical and biological characteristics of the phosphatidylinositol (PI) derivative...
BACKGROUND/AIMS
The present study was conducted to understand biochemical and biological characteristics of the phosphatidylinositol (PI) derivative 1,2-O-bis-[8-{2-(2-pentyl-cyclopropylmethyl)-cyclopropyl}-octanoyl]-Sn-glycero-3-phosphatidyl-D-1-inositol (diDCP-LA-PI) and its enantiomer 1,2-O-bis-[8-{2-(2-pentyl-cyclopropylmethyl)-cyclopropyl}-octanoyl]-Sn-glycero-3-phosphatidyl-L-1-inositol (diDCP-LA-PIe), with 8-[2-(2-pentyl-cyclopropylmethyl)-cyclopropyl]-octanoic acid (DCP-LA) on the α and β position.
METHODS
Activities of protein kinase C (PKC) and protein phosphatases such as protein phosphatase 1 (PP1), PP2A, and protein tyrosine phosphatase 1B (PTP1B) were assayed under the cell-free conditions and in PC-12 cells. Akt1/2 activity was monitored by quantifying phosphorylation at Thr308/309 and Ser473/474 in PC-12 cells.
RESULTS
diDCP-LA-PI significantly activated PKCα, -βΙ, -δ, and -ε, to an extent greater than that for diDCP-LA-PIe. diDCP-LA-PI still activated PKC in PC-12 cells, with the potential higher than that for diDCP-LA-PIe. Both diDCP-LA-PI and diDCP-LA-PIe reduced PP1 activity to a similar extent (30% of basal levels). diDCP-LA-PI enhanced PP2A activity to 180% of basal levels, while diDCP-LA-PIe had no effect. Drastic inhibition of PTP1B was obtained with diDCP-LA-PI and diDCP-LA-PIe, the extent reaching nearly 0% of basal levels. diDCP-LA-PI and diDCP-LA-PIe increased phosphorylation of Akt1/2 at Thr308/309 and Ser473/474 in PC-12 cells in the presence and absence of the PP2A inhibitor okadaic acid, respectively.
CONCLUSION
The results of the present study show that diDCP-LA-PI and diDCP-LA-PIe exhibit different bioactivities with the different potentials each other.
Topics: Animals; PC12 Cells; Phosphatidylinositols; Phosphoprotein Phosphatases; Phosphorylation; Protein Kinases; Rats
PubMed: 24525749
DOI: 10.1159/000356670 -
Bioorganic & Medicinal Chemistry Aug 2006Phosphatidylinositol mannoside (PIM) extracts from mycobacteria have been shown previously to suppress allergic airway inflammation in mice. To help determine the...
Phosphatidylinositol mannoside (PIM) extracts from mycobacteria have been shown previously to suppress allergic airway inflammation in mice. To help determine the structural requirements for activity, PIM1(2) (1), PIM1(6) (2) and PIM2 (3) were synthesized and tested for their ability to suppress cellular inflammation in a mouse model of allergic asthma. The synthetic PIMs were all effective in suppressing airway eosinophilia in the asthma model, with PIM1(6) being the most effective. Suppression of all inflammatory cells monitored was observed, indicating a general blockade of cellular inflammation. Non-mannosylated phosphatidylinositol (PI) had no suppressive effect, indicating that at least one alpha-d-mannopyranosyl residue is necessary for activity. The suppressive effect of the three PIM compounds indicates that other members of this set may be of value in treatment of a range of diseases driven by infiltration of inflammatory cells.
Topics: Animals; Anti-Allergic Agents; Asthma; Inflammation; Mice; Mice, Inbred C57BL; Phosphatidylinositols; Respiratory Hypersensitivity; Structure-Activity Relationship
PubMed: 16697208
DOI: 10.1016/j.bmc.2006.04.037 -
The Biochemical Journal Oct 19801. The lower regions of the stem of celery (Apium graveolens L.) contain a soluble enzyme that hydrolyses phosphatidylinositol. 2. The lipoidal product of hydrolysis is...
1. The lower regions of the stem of celery (Apium graveolens L.) contain a soluble enzyme that hydrolyses phosphatidylinositol. 2. The lipoidal product of hydrolysis is diacylglycerol, and the water-soluble products are 1:2-cyclic phosphoinositol and phosphoinositol in the approximate proportions of 60% and 40% respectively: this indicates that a phosphodiesterase (phospholipase C-like) activity is cleaving the phosphatidylinositol. 3. The enzyme requires a bivalent cation, Ca2+ being the most effective activator. 4. The enzyme has a pH optimum, depending on conditions of assay, of pH 5.9-6.6 and in this pH range shows no detectable activity against phosphatidylcholine or phosphatidylethanolamine. 5. The activity is stimulated by phosphatidic acid and slightly inhibited (30% at concentrations equimolar with phosphatidylinositol) by phosphatidylcholine. 6. The phosphodiesterase was also detected (but not quantified) in the tips of the flowers in cauliflowers, in outer leaves of onion and in the elongating stem of daffodils. 7. The enzyme's properties are compared with equivalent mammalian enzymes, and its possible role in the catabolism of phosphatidylinositol in higher plants is discussed.
Topics: Cations; Hydrogen-Ion Concentration; Hydrolysis; Phosphatidylinositol Diacylglycerol-Lyase; Phosphatidylinositols; Phospholipids; Phosphoric Diester Hydrolases; Plants; Substrate Specificity
PubMed: 6272700
DOI: 10.1042/bj1920279 -
Methods in Enzymology 2007The activation of class I phosphoinositide 3-kinases (PI(3)Ks) by cell surface receptors represents the initiation of a large and complex signaling network that couples...
The activation of class I phosphoinositide 3-kinases (PI(3)Ks) by cell surface receptors represents the initiation of a large and complex signaling network that couples many growth factors, antigens, and inflammatory stimuli to important cellular responses, such as cell growth, survival, and movement. The most direct measurement of class I PI(3)K activity in cells is the rate of production of its lipid product, phosphatidylinositol 3,4,5-trisphosphate [PtdIns(3,4,5)P(3)]. This chapter describes in detail two approaches used to estimate the levels of PtdIns(3,4,5)P(3) in cells. One approach uses radiotracer labeling of cells, lipid extraction, deacylation, and subsequent quantitation of phosphoinositides by anion-exchange high-performance liquid chromatography. The second approach uses a novel, nonradioactive assay in which the cellular lipids are extracted, phosphoinositides are enriched through binding to a neomycin matrix, dried onto a nitrocellulose membrane, and PtdIns(3,4,5)P(3) quantified by a protein-lipid overlay approach using a GRP(1) PH domain probe.
Topics: 1-Phosphatidylinositol 4-Kinase; Animals; Cell Line; Cell Physiological Phenomena; Chromatography, Ion Exchange; Humans; Indicators and Reagents; Isotope Labeling; Lipids; Neutrophils; Phosphates; Phosphatidylinositol Phosphates; Phosphatidylinositols; Phosphorus Radioisotopes; Receptors, Cytoplasmic and Nuclear
PubMed: 17954245
DOI: 10.1016/S0076-6879(07)34007-X -
The Journal of Cell Biology Sep 2023The lipid phosphatidylinositol 3,5-bisphosphate-PI(3,5)P2-is known to be a key regulator of cellular traffic in health and disease, but its cellular localization was...
The lipid phosphatidylinositol 3,5-bisphosphate-PI(3,5)P2-is known to be a key regulator of cellular traffic in health and disease, but its cellular localization was somewhat enigmatic until now, with the discovery of a new PI(3,5)P2 biosensor reported in this issue of JCB by Vines et al. (2023. J. Cell Biol.https://doi.org/10.1083/jcb.202209077).
Topics: Phosphatidylinositol Phosphates; Phosphatidylinositols; Biosensing Techniques
PubMed: 37578524
DOI: 10.1083/jcb.202308004 -
EMBO Reports Oct 2014Phosphoinositides are a class of phospholipids generated by the action of phosphoinositide kinases with key regulatory functions in eukaryotic cells. Here, we present...
Phosphoinositides are a class of phospholipids generated by the action of phosphoinositide kinases with key regulatory functions in eukaryotic cells. Here, we present the atomic structure of phosphatidylinositol 4-kinase type IIα (PI4K IIα), in complex with ATP solved by X-ray crystallography at 2.8 Å resolution. The structure revealed a non-typical kinase fold that could be divided into N- and C-lobes with the ATP binding groove located in between. Surprisingly, a second ATP was found in a lateral hydrophobic pocket of the C-lobe. Molecular simulations and mutagenesis analysis revealed the membrane binding mode and the putative function of the hydrophobic pocket. Taken together, our results suggest a mechanism of PI4K IIα recruitment, regulation, and function at the membrane.
Topics: Binding Sites; Crystallography, X-Ray; Humans; Inositol; Membranes; Minor Histocompatibility Antigens; Monte Carlo Method; Phosphatidylinositols; Phosphotransferases (Alcohol Group Acceptor); Protein Binding; Protein Conformation; Signal Transduction
PubMed: 25168678
DOI: 10.15252/embr.201438841 -
Chemistry and Physics of Lipids Apr 1999In eukaryotic cells, phosphatidylinositol can be phosphorylated on the inositol ring by a series of kinases to produce at least seven distinct phosphoinositides. These... (Review)
Review
In eukaryotic cells, phosphatidylinositol can be phosphorylated on the inositol ring by a series of kinases to produce at least seven distinct phosphoinositides. These lipids have been implicated in a variety of cellular processes, including calcium regulation, actin rearrangement, vesicle trafficking, cell survival and mitogenesis. The phosphorylated lipids can act as precursors of second messengers or act directly to recruit specific signaling proteins to the membrane. A number of the kinases responsible for producing these lipids have been purified and their cDNA clones have been isolated. The most well characterized of these enzymes are the phosphoinositide 3-kinases. However, progress has also been made in the characterization of phosphatidylinositol 4-kinases and phosphatidylinositol-4-phosphate 5-kinases. In addition, new pathways involving phosphatidylinositol-5-phosphate 4-kinases, phosphatidylinositol-3-phosphate 5-kinases and phosphatidylinositol-3-phosphate 4-kinases have recently been described. The various enzymes and pathways involved in the synthesis of cellular phosphoinositides will be discussed.
Topics: Animals; Calcium; Humans; Models, Chemical; Phosphatidylinositols; Phosphorylation; Phosphotransferases; Saccharomyces cerevisiae; Signal Transduction
PubMed: 10358929
DOI: 10.1016/s0009-3084(99)00019-5 -
The Biochemical Journal Nov 2022In the almost 70 years since the first hints of its existence, the phosphoinositide, phosphatidyl-D-myo-inositol 4,5-bisphosphate has been found to be central in the...
In the almost 70 years since the first hints of its existence, the phosphoinositide, phosphatidyl-D-myo-inositol 4,5-bisphosphate has been found to be central in the biological regulation of plasma membrane (PM) function. Here, we provide an overview of the signaling, transport and structural roles the lipid plays at the cell surface in animal cells. These include being substrate for second messenger generation, direct modulation of receptors, control of membrane traffic, regulation of ion channels and transporters, and modulation of the cytoskeleton and cell polarity. We conclude by re-evaluating PI(4,5)P2's designation as a signaling molecule, instead proposing a cofactor role, enabling PM-selective function for many proteins.
Topics: Animals; Cell Membrane; Phosphatidylinositols; Signal Transduction; Ion Channels; Phosphatidylinositol 4,5-Diphosphate
PubMed: 36367756
DOI: 10.1042/BCJ20220445