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Vytas A Bankaitis - One of the best experts on this subject based on the ideXlab platform.
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neural stem cell interkinetic nuclear migration is controlled by a Phosphatidylinositol Transfer Protein non canonical planar cell polarity signaling axis
bioRxiv, 2020Co-Authors: Zhigang Xie, Vytas A BankaitisAbstract:The mammalian neocortex undergoes explosive expansion during embryonic development. From an evolutionary perspective, higher complexity of the neocortex is accompanied by a prominent expansion in its lateral dimension so that the neocortical surface area is increased. Expansion in the radial dimension throughout evolution is limited so that neocortical thickness is strongly restricted1-3. The underlying mechanisms for restricting neocortical thickness remain unclear. Expansion of the developing mouse neocortex is driven by neurogenesis which is itself primarily fueled by neural stem cells (NSCs). NSCs form a pseudostratified epithelium and exhibit a hallmark cell cycle-dependent nuclear movement termed interkinetic nuclear migration (IKNM) 2-4. While IKNM plays a critical role in cell fate determination, it remains a poorly understood process. Herein, we demonstrate IKNM relies on a Phosphatidylinositol Transfer Protein (PITP)-noncanonical planar cell polarity (ncPCP) signaling axis that restricts radial expansion of the developing neocortex. Ablation of PITPα/PITPβ in NSCs compromised IKNM -- resulting in a thickened neocortex and perturbed curvature of its ventricular surface. Those phenotypic derangements in IKNM and neocortical morphogenesis were recapitulated in mouse embryos individually ablated for two ncPCP receptor gene activities and in a mosaic neocortex expressing a dominant-negative variant of a third ncPCP receptor. Finally, PITP signaling links to ncPCP pathway activity by promoting membrane trafficking of a subset of ncPCP receptors from the trans-Golgi network to the NSC cell surface. We conclude IKNM is a driving force for a special form of convergent extension regulated by coupling PITP-mediated phosphoinositide signaling with activity of the evolutionarily conserved ncPCP pathway.
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functional diversification of the chemical landscapes of yeast sec14 like Phosphatidylinositol Transfer Protein lipid binding cavities
Journal of Biological Chemistry, 2020Co-Authors: Ashutosh Tripathi, Danish Khan, Max Lonnfors, Carl J Mousley, Elliott Martinez, Ahmad J Obaidullah, Marta G Lete, Krishnakant G Soni, Glen E Kellogg, Vytas A BankaitisAbstract:Phosphatidylinositol-Transfer Proteins (PITPs) are key regulators of lipid signaling in eukaryotic cells. These Proteins both potentiate the activities of Phosphatidylinositol (PtdIns) 4-OH kinases and help channel production of specific pools of Phosphatidylinositol 4-phosphate (PtdIns(4)P) dedicated to specific biological outcomes. In this manner, PITPs represent a major contributor to the mechanisms by which the biological outcomes of phosphoinositide are diversified. The two-ligand priming model proposes that the engine by which Sec14-like PITPs potentiate PtdIns kinase activities is a heterotypic lipid-exchange cycle where PtdIns is a common exchange substrate among the Sec14-like PITP family, but the second exchange ligand varies with the PITP. A major prediction of this model is that second-exchangeable ligand identity will vary from PITP to PITP. To address the heterogeneity in the second exchange ligand for Sec14-like PITPs, we used structural, computational, and biochemical approaches to probe the diversities of the lipid-binding cavity microenvironments of the yeast Sec14-like PITPs. The collective data report that yeast Sec14-like PITP lipid-binding pockets indeed define diverse chemical microenvironments that translate into differential ligand-binding specificities across this Protein family.
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non canonical regulation of phosphatidylserine metabolism by a Phosphatidylinositol Transfer Protein and a Phosphatidylinositol 4 oh kinase
bioRxiv, 2019Co-Authors: Vytas A Bankaitis, Ashutosh Tripathi, Yaxi Wang, Peihua Yuan, Martin Rodriguez, Max Lonnfors, Michal Eisenbergbord, Maya SchuldinerAbstract:ABSTRACT The phosphatidylserine (PtdSer) decarboxylase Psd2 is proposed to engage in an endoplasmic reticulum (ER)-Golgi/endosome membrane contact site (MCS) that facilitates phosphatidylserine decarboxylation to phosphatidylethanomaine (PtdEtn) in Saccharomyces cerevisiae. While this MCS is envisioned to consist of Psd2, the Sec14-like Phosphatidylinositol Transfer Protein (PITP) Sfh4, the Stt4 Phosphatidylinositol (PtdIns) 4-OH kinase, the Scs2 tether, and at least one other uncharacterized Protein, functional data that address key foundations of this model are sparse. We now report that Psd2, Sfh4 and Stt4 are the only components individually required for biologically sufficient Psd2-dependent PtdEtn production. Surprisingly, neither the PtdIns-Transfer activity of Sfh4 nor its capacity to activate Stt4 is required to stimulate the Psd2 pathway. Instead, Sfh4 activates the Psd2 pathway via a specific Sfh4-Psd2 physical interaction. Whereas the data indicate an Sfh4-independent association of Stt4 with Psd2 as well, we find Stt4 also regulates Psd2 activity indirectly by influencing the PtdSer pool accessible to Psd2 for decarboxylation. These collective results demonstrate that the proposed ER-Golgi/endosomal MCS model fails to provide an accurate description of the Psd2 system in yeast, and provide an example where the biological function of a Sec14-like PITP is uncoupled from its ‘canonical’ activity as a PtdIns Transfer Protein.
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the interface between Phosphatidylinositol Transfer Protein function and phosphoinositide signaling in higher eukaryotes
Journal of Lipid Research, 2019Co-Authors: Aby Grabon, Vytas A Bankaitis, Mark I McdermottAbstract:Phosphoinositides are key regulators of a large number of diverse cellular processes that include membrane trafficking, plasma membrane receptor signaling, cell proliferation, and transcription. How a small number of chemically distinct phosphoinositide signals are functionally amplified to exert specific control over such a diverse set of biological outcomes remains incompletely understood. To this end, a novel mechanism is now taking shape, and it involves Phosphatidylinositol (PtdIns) Transfer Proteins (PITPs). The concept that PITPs exert instructive regulation of PtdIns 4-OH kinase activities and thereby channel phosphoinositide production to specific biological outcomes, identifies PITPs as central factors in the diversification of phosphoinositide signaling. There are two evolutionarily distinct families of PITPs: the Sec14-like and the StAR-related lipid Transfer domain (START)-like families. Of these two families, the START-like PITPs are the least understood. Herein, we review recent insights into the biochemical, cellular, and physiological function of both PITP families with greater emphasis on the START-like PITPs, and we discuss the underlying mechanisms through which these Proteins regulate phosphoinositide signaling and how these actions translate to human health and disease.
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the pathologies associated with functional titration of Phosphatidylinositol Transfer Protein α activity in mice
Journal of Lipid Research, 2007Co-Authors: James G Alb, Scott E. Phillips, Lindsey R Wilfley, Benjamin D Philpot, Vytas A BankaitisAbstract:Phosphatidylinositol Transfer Proteins (PITPs) bind Phosphatidylinositol (PtdIns) and phosphatidylcholine and play diverse roles in coordinating lipid metabolism/signaling with intracellular functions. The underlying mechanisms remain unclear. Genetic ablation of PITPα in mice results in neonatal lethality characterized by intestinal and hepatic steatosis, spinocerebellar neurodegeneration, and glucose homeostatic defects. We report that mice expressing a PITPα selectively ablated for PtdIns binding activity (PitpαT59D), as the sole source of PITPα, exhibit phenotypes that recapitulate those of authentic PITPα nullizygotes. Analyses of mice with graded reductions in PITPα activity reveal proportionately graded reductions in lifespan, demonstrate that intestinal steatosis and hypoglycemia are apparent only when PITPα Protein levels are strongly reduced (⩾90%), and correlate steatotic and glucose homeostatic defects with cerebellar inflammatory disease. Finally, reconstitution of PITPα expression in the small intestine substantially corrects the chylomicron retention disease and cerebellar inflammation of Pitpα0/0 neonates, but does not rescue neonatal lethality in these animals. These data demonstrate that PtdIns binding is an essential functional property of PITPα in vivo, and suggest a causal linkage between defects in lipid transport and glucose homeostasis and cerebellar inflammatory disease. Finally, the data also demonstrate intrinsic neuronal deficits in PITPα-deficient mice that are independent of intestinal lipid transport defects and hypoglycemia.
Shamshad Cockcroft - One of the best experts on this subject based on the ideXlab platform.
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yeast Phosphatidylinositol Transfer Protein pdr17 does not require high affinity Phosphatidylinositol binding for its cellular function
Biochimica et Biophysica Acta, 2019Co-Authors: Zuzana Pevalova, Roman Holic, Vladimir Pevala, Nicholas J Blunsom, Dana Tahotna, Veronika Kotrasova, Lucia Pokorna, Jacob A Bauer, Eva Kutejova, Shamshad CockcroftAbstract:Yeast Phosphatidylinositol Transfer Protein (PITP) Pdr17 is an essential component of the complex required for decarboxylation of phosphatidylserine (PS) to phosphatidylethanolamine (PE) at a non-mitochondrial location. According to current understanding, this process involves the Transfer of PS from the endoplasmic reticulum to the Golgi/endosomes. We generated a Pdr17E237A, K269A mutant Protein to better understand the mechanism by which Pdr17p participates in the processes connected to the decarboxylation of PS to PE. We show that the Pdr17E237A, K269A mutant Protein is not capable of binding Phosphatidylinositol (PI) using permeabilized human cells, but still retains the ability to Transfer PI between two membrane compartments in vitro. We provide data together with molecular models showing that the mutations E237A and K269A changed only the lipid binding cavity of Pdr17p and not its surface properties. In contrast to Pdr16p, a close homologue, the ability of Pdr17p to bind PI is not required for its major cellular function in the inter-membrane Transfer of PS. We hypothesize that these two closely related yeast PITPs, Pdr16p and Pdr17p, have evolved from a common ancestor. Pdr16p fulfills those role(s) in which the ability to bind and Transfer PI is required, while Pdr17p appears to have adapted to a different role which does not require the high affinity binding of PI, although the Protein retains the capacity to Transfer PI. Our results indicate that PITPs function in complex ways in vivo and underscore the need to consider multiple PITP parameters when studying these Proteins in vitro.
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Phosphatidylinositol Transfer Protein α in platelets is inconsequential for thrombosis yet is utilized for tumor metastasis
Nature Communications, 2017Co-Authors: Liang Zhao, Shamshad Cockcroft, Chelsea Thorsheim, Aae Suzuki, Timothy J Stalker, Sang H Min, Lurong Lian, Gregory D Fairn, Amy C Durham, Sriram KrishnaswamyAbstract:Platelets are increasingly recognized for their contributions to tumor metastasis. Here, we show that the phosphoinositide signaling modulated by Phosphatidylinositol Transfer Protein type α (PITPα), a Protein which shuttles Phosphatidylinositol between organelles, is essential for platelet-mediated tumor metastasis. PITPα-deficient platelets have reduced intracellular pools of phosphoinositides and an 80% reduction in IP3 generation upon platelet activation. Unexpectedly, mice lacking platelet PITPα form thrombi normally at sites of intravascular injuries. However, following intravenous injection of tumor cells, mice lacking PITPα develop fewer lung metastases due to a reduction of fibrin formation surrounding the tumor cells, rendering the metastases susceptible to mucosal immunity. These findings demonstrate that platelet PITPα-mediated phosphoinositide signaling is inconsequential for in vivo hemostasis, yet is critical for in vivo dissemination. Moreover, this demonstrates that signaling pathways within platelets may be segregated into pathways that are essential for thrombosis formation and pathways that are important for non-hemostatic functions.
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potential role for Phosphatidylinositol Transfer Protein pitp family in lipid Transfer during phospholipase c signalling
Advances in biological regulation, 2013Co-Authors: Shamshad Cockcroft, Kathryn GarnerAbstract:The hallmark of mammalian Phosphatidylinositol Transfer Proteins (PITPs) is to Transfer Phosphatidylinositol between membrane compartments. In the mammalian genome, there are three genes that code for soluble PITP Proteins, PITPα, PITPβ and RdgBβ and two genes that code for membrane-associated multi-domain Proteins (RdgBαI and II) containing a PITP domain. PITPα and PITPβ constitute Class I PITPs whilst the RdgB Proteins constitute Class II Proteins based on sequence analysis. The PITP domain of both Class I and II can sequester one molecule of Phosphatidylinositol (PI) in its hydrophobic cavity. Therefore, in principle, PITPs are therefore ideally poised to couple Phosphatidylinositol delivery to the PI kinases for substrate provision for phospholipases C during cell activation. Since Phosphatidylinositol (4,5)bisphosphate plays critical roles in cells, particularly at the plasma membrane, where it is a substrate for both phospholipase C and phosphoinositide-3-kinases as well as required as an intact lipid to regulate ion channels and the actin cytoskeleton, homeostatic mechanisms to maintain Phosphatidylinositol(4,5)bisphosphate levels are vital. To maintain Phosphatidylinositol levels, phospholipase C activation inevitably leads to the resynthesis of PI at the endoplasmic reticulum where the enzymes are located. Phosphatidic acid generated at the plasma membrane during phospholipase C activation needs to move to the ER for conversion to PI and here we provide evidence that Class II PITPs are also able to bind and transport phosphatidic acid. Thus RdgB Proteins could couple PA and PI transport bidirectionally during phospholipase C signalling.
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Phosphatidylinositol Transfer Protein cytoplasmic 1 pitpnc1 binds and Transfers phosphatidic acid
Journal of Biological Chemistry, 2012Co-Authors: Kathryn Garner, Pentti Somerharju, Roman Holic, Alan N Hunt, Grielof Koster, Emily Groves, Padinjat Raghu, Shamshad CockcroftAbstract:Phosphatidylinositol Transfer Proteins (PITPs) are versatile Proteins required for signal transduction and membrane traffic. The best characterized mammalian PITPs are the Class I PITPs, PITPα (PITPNA) and PITPβ (PITPNB), which are single domain Proteins with a hydrophobic cavity that binds a Phosphatidylinositol (PI) or phosphatidylcholine molecule. In this study, we report the lipid binding properties of an uncharacterized soluble PITP, Phosphatidylinositol Transfer Protein, cytoplasmic 1 (PITPNC1) (alternative name, RdgBβ), of the Class II family. We show that the lipid binding properties of this Protein are distinct to Class I PITPs because, besides PI, RdgBβ binds and Transfers phosphatidic acid (PA) but hardly binds phosphatidylcholine. RdgBβ when purified from Escherichia coli is preloaded with PA and phosphatidylglycerol. When RdgBβ was incubated with permeabilized HL60 cells, phosphatidylglycerol was released, and PA and PI were now incorporated into RdgBβ. After an increase in PA levels following activation of endogenous phospholipase D or after addition of bacterial phospholipase D, binding of PA to RdgBβ was greater at the expense of PI binding. We propose that RdgBβ, when containing PA, regulates an effector Protein or can facilitate lipid Transfer between membrane compartments.
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function of the Phosphatidylinositol Transfer Protein gene family is Phosphatidylinositol Transfer the mechanism of action
Critical Reviews in Biochemistry and Molecular Biology, 2011Co-Authors: Shamshad Cockcroft, Kathryn GarnerAbstract:Phosphatidylinositol Transfer Proteins (PITPs) bind and facilitate the transport of Phosphatidylinositol (PI) and phosphatidylcholine between membrane compartments. They are highly conserved Proteins, are found in both unicellular and multicellular organisms, and can be present as a single domain or as part of a larger, multi-domain Protein. The hallmark of PITP Proteins is their ability to sequester PI in their hydrophobic pocket. Ablation or knockdown of specific isoforms in vivo has wide ranging effects such as defects in signal transduction via phospholipase C and phosphoinositide 3-kinase, membrane trafficking, stem cell viability, Drosophila phototransduction, neurite outgrowth, and cytokinesis. In this review, we identify the common mechanism underlying each of these phenotypes as the cooperation between PITP Proteins and lipid kinases through the provision of PI for phosphorylation. We propose that recruitment and concentration of PITP Proteins at specific membrane sites are required for PITP Proteins to execute their function rather than lipid Transfer.
Karel W. A. Wirtz - One of the best experts on this subject based on the ideXlab platform.
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the anti apoptotic activity associated with Phosphatidylinositol Transfer Protein α activates the mapk and akt pkb pathway
Biochimica et Biophysica Acta, 2008Co-Authors: Martijn Schenning, Karel W. A. Wirtz, Joachim Goedhart, Theodorus W J Gadella, Diana Avram, Gerry T SnoekAbstract:The conditioned medium (CM) from mouse NIH3T3 fibroblast cells overexpressing Phosphatidylinositol Transfer Protein α (PI-TPα; SPIα cells) demonstrates an increased anti-apoptotic activity compared with CM from wild type NIH3T3 (wtNIH3T3) cells. As previously shown, the anti-apoptotic activity acts by activating a G Protein-coupled receptor, most probably a cannabinoid 1 (CB1)-like receptor as the activity was blocked by both pertussis toxin and rimonabant [M. Schenning, C.M. van Tiel, D. Van Manen, J.C. Stam, B.M. Gadella, K.W. Wirtz and G.T. Snoek, Phosphatidylinositol Transfer Protein alpha regulates growth and apoptosis of NIH3T3 cells: involvement of a cannabinoid 1-like receptor, J. Lipid Res. 45 (2004) 1555-1564]. The CB1 receptor appears to be expressed in mouse fibroblast cells, at levels in the order SPIα > wtNIH3T3 > SPIβ cells (i.e. wild type cells overexpressing PI-TPβ). Upon incubation of SPIβ cells with the PI-TPα-dependent anti-apoptotic factors, both the ERK/MAP kinase and the Akt/PKB pathway are activated in a CB1 receptor dependent manner as shown by Western blotting. In addition, activation of ERK2 was also shown by EYFP-ERK2 translocation to the nucleus, as visualized by confocal laser scanning microscopy. The subsequent activation of the anti-apoptotic transcription factor NF-κB is in line with the increased resistance towards UV-induced apoptosis. On the other hand, receptor activation by CM from SPIα cells was not linked to phospholipase C activation as the YFP-labelled C2-domain of Protein kinase C was not translocated to the plasma membrane of SPIβ cells as visualized by confocal laser scanning microscopy.
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the anti apoptotic map kinase pathway is inhibited in nih3t3 fibroblasts with increased expression of Phosphatidylinositol Transfer Protein β
Biochimica et Biophysica Acta, 2007Co-Authors: Martijn Schenning, Karel W. A. Wirtz, Claudia M Van Tiel, Gerry T SnoekAbstract:Mouse NIH3T3 fibroblast cells overexpressing Phosphatidylinositol Transfer Protein s (PI-TPs, SPIs cells) demonstrate a low rate of proliferation and a high sensitivity towards UV-induced apoptosis when compared with wtNIH3T3 cells. In contrast, SPIsS262A cells overexpressing a mutant PI-TPs that lacks the Protein kinase C-dependent phosphorylation site Ser-262, demonstrate a phenotype comparable with wtNIH3T3 cells. This suggests that the phosphorylation of Ser-262 in PI-TPs is involved in the regulation of apoptosis. Conditioned medium (CM) from wtNIH3T3 cells contains bioactive factors, presumably arachidonic acid metabolites [H. Bunte, et al., 2006; M. Schenning, et al., 2004] that are able to protect SPIs cells against UV-induced apoptosis.CMfrom SPIs cells lacks this protective activity. However, after heat denaturation CM from SPIs cells regains a protective activity comparable with that of wtNIH3T3 cells. This indicates that CM from SPIs cells contains an antagonistic factor interfering with the anti-apoptotic activity present. SPIsS262A cells do not produce the antagonist suggesting that phosphorylation of Ser-262 is required. Moreover, in line with the apparent lack of anti-apoptotic activity, CM from SPIs cells does not induce the expression of COX-2 or the activation of p42/p44 MAP kinase in SPIs cells. In contrast, CM from wtNIH3T3 and SPIsS262A cells or heat-treated CM from SPIs cells does induce these anti-apoptotic markers. Since we have previously shown that some of the arachidonic acid metabolites present in CM from wtNIH3T3 cells are prostaglandin (PG) E2 and PGF2a, we investigated the effect of these PGs on cell survival. Although PGE2 and PGF2a were found to protect wtNIH3T3 and SPIsS262A cells against UV-induced apoptosis, these PGs failed to rescue SPIs cells. The fact that the concentrations of PGE2 and PGF2a in the CM from SPIs cells and wtNIH3T3 cells were found to be comparable suggests that the failure of these PGs to protect SPIs cells could render these cells more apoptosis sensitive. Concomitantly, upon incubation with PGE2 and PGF2a, an increased expression of COX-2 and activation of p42/p44 MAP kinase were observed in wtNIH3T3 and SPIsS262A cells but not in SPIs cells. Hence, it appears that specific mechanisms of cell survival are impaired in SPIs cells.
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a Phosphatidylinositol Transfer Protein α dependent survival factor protects cultured primary neurons against serum deprivation induced cell death
Journal of Neurochemistry, 2006Co-Authors: Karel W. A. Wirtz, Martijn Schenning, Hanneke Bunte, Peter Sodaar, Dop P R Bar, Freek L Van Muiswinkel, Gerry T SnoekAbstract:Selective neuronal loss is a prominent feature in both acute and chronic neurological disorders. Recently, a link between neurodegeneration and a deficiency in the lipid transport Protein Phosphatidylinositol Transfer Protein α (PI-TPα) has been demonstrated. In this context it may be of importance that fibroblasts overexpressing PI-TPα are known to produce and secrete bioactive survival factors that protect fibroblasts against UV-induced apoptosis. In the present study it was investigated whether the conditioned medium of cells overexpressing PI-TPα (CMα) has neuroprotective effects on primary neurons in culture. We show that CMα is capable of protecting primary, spinal cord-derived motor neurons from serum deprivation-induced cell death. Since the conditioned medium of wild-type cells was much less effective, we infer that the neuroprotective effect of CMα is linked (in part) to the PI-TPα-dependent production of arachidonic acid metabolites. The neuroprotective activity of CMα is partly inhibited by suramin, a broad-spectrum antagonist of G-Protein coupled receptors. Western blot analysis shows that brain cortex and spinal cord express relatively high levels of PI-TPα, suggesting that the survival factor may be produced in neuronal tissue. We propose that the bioactive survival factor is implicated in neuronal survival. If so, PI-TPα could be a promising target to be evaluated in studies on the prevention and treatment of neurological disorders.
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Phosphatidylinositol Transfer Protein α regulates growth and apoptosis of nih3t3 cells involvement of a cannabinoid 1 like receptor
Journal of Lipid Research, 2004Co-Authors: Martijn Schenning, Karel W. A. Wirtz, Claudia M Van Tiel, Danielle Van Manen, Jord C Stam, Barend M Gadella, Gerry T SnoekAbstract:Mouse fibroblast cells overexpressing Phosphatidylinositol Transfer Protein α [PI-TPα; sense PI-TPα (SPIα) cells] show a significantly increased rate of proliferation and an extreme resistance toward ultraviolet- or tumor necrosis factor-α-induced apoptosis. The conditioned medium (CM) from SPIα cells or the neutral lipid extract from CM stimulated the proliferation of quiescent wild-type NIH3T3 cells. CM was also highly effective in increasing resistance toward induced apoptosis in both wild-type cells and the highly apoptosis-sensitive SPIβ cells (i.e., wild-type cells overexpressing PI-TPβ). CM from SPIα cells grown in the presence of NS398, a specific cyclooxygenase-2 (COX-2) inhibitor, expressed a diminished mitogenic and antiapoptotic activity. This strongly suggests that at least one of the bioactive factor(s) is an eicosanoid. In accordance, SPIα cells express enhanced levels of COX-1 and COX-2. The antiapoptotic activity of CM from SPIα cells tested on SPIβ cells was inhibited by ∼50% by pertussis toxin and suramin as well as by SR141716A, a specific antagonist of the cannabinoid 1 receptor. These inhibitors had virtually no effect on the COX-2-independent antiapoptotic activity of CM from SPIα cells.. The latter results imply that PI-TPα mediates the production of a COX-2-dependent eicosanoid that activates a G-Protein-coupled receptor, most probably a cannabinoid 1-like receptor.
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the structure of Phosphatidylinositol Transfer Protein α reveals sites for phospholipid binding and membrane association with major implications for its function
FEBS Letters, 2002Co-Authors: Claudia M Van Tiel, Arie Schouten, Gerry T Snoek, Piet Gros, Karel W. A. WirtzAbstract:Elucidation of the three-dimensional structure of Phosphatidylinositol Transfer Protein α (PI-TPα) void of phospholipid revealed a site of membrane association connected to a channel for phospholipid binding. Near the top of the channel specific binding sites for the phosphorylcholine and phosphorylinositol head groups were identified. The structure of this open form suggests a mechanism by which PI-TPα preferentially binds PI from a membrane interface. Modeling predicts that upon association of PI-TPα with the membrane the inositol moiety of bound PI is accessible from the medium. Upon release from the membrane PI-TPα adopts a closed structure with the phospholipid bound fully encapsulated. This structure provides new insights as to how PI-TPα may play a role in PI metabolism.
Gerry T Snoek - One of the best experts on this subject based on the ideXlab platform.
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the anti apoptotic activity associated with Phosphatidylinositol Transfer Protein α activates the mapk and akt pkb pathway
Biochimica et Biophysica Acta, 2008Co-Authors: Martijn Schenning, Karel W. A. Wirtz, Joachim Goedhart, Theodorus W J Gadella, Diana Avram, Gerry T SnoekAbstract:The conditioned medium (CM) from mouse NIH3T3 fibroblast cells overexpressing Phosphatidylinositol Transfer Protein α (PI-TPα; SPIα cells) demonstrates an increased anti-apoptotic activity compared with CM from wild type NIH3T3 (wtNIH3T3) cells. As previously shown, the anti-apoptotic activity acts by activating a G Protein-coupled receptor, most probably a cannabinoid 1 (CB1)-like receptor as the activity was blocked by both pertussis toxin and rimonabant [M. Schenning, C.M. van Tiel, D. Van Manen, J.C. Stam, B.M. Gadella, K.W. Wirtz and G.T. Snoek, Phosphatidylinositol Transfer Protein alpha regulates growth and apoptosis of NIH3T3 cells: involvement of a cannabinoid 1-like receptor, J. Lipid Res. 45 (2004) 1555-1564]. The CB1 receptor appears to be expressed in mouse fibroblast cells, at levels in the order SPIα > wtNIH3T3 > SPIβ cells (i.e. wild type cells overexpressing PI-TPβ). Upon incubation of SPIβ cells with the PI-TPα-dependent anti-apoptotic factors, both the ERK/MAP kinase and the Akt/PKB pathway are activated in a CB1 receptor dependent manner as shown by Western blotting. In addition, activation of ERK2 was also shown by EYFP-ERK2 translocation to the nucleus, as visualized by confocal laser scanning microscopy. The subsequent activation of the anti-apoptotic transcription factor NF-κB is in line with the increased resistance towards UV-induced apoptosis. On the other hand, receptor activation by CM from SPIα cells was not linked to phospholipase C activation as the YFP-labelled C2-domain of Protein kinase C was not translocated to the plasma membrane of SPIβ cells as visualized by confocal laser scanning microscopy.
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the anti apoptotic map kinase pathway is inhibited in nih3t3 fibroblasts with increased expression of Phosphatidylinositol Transfer Protein β
Biochimica et Biophysica Acta, 2007Co-Authors: Martijn Schenning, Karel W. A. Wirtz, Claudia M Van Tiel, Gerry T SnoekAbstract:Mouse NIH3T3 fibroblast cells overexpressing Phosphatidylinositol Transfer Protein s (PI-TPs, SPIs cells) demonstrate a low rate of proliferation and a high sensitivity towards UV-induced apoptosis when compared with wtNIH3T3 cells. In contrast, SPIsS262A cells overexpressing a mutant PI-TPs that lacks the Protein kinase C-dependent phosphorylation site Ser-262, demonstrate a phenotype comparable with wtNIH3T3 cells. This suggests that the phosphorylation of Ser-262 in PI-TPs is involved in the regulation of apoptosis. Conditioned medium (CM) from wtNIH3T3 cells contains bioactive factors, presumably arachidonic acid metabolites [H. Bunte, et al., 2006; M. Schenning, et al., 2004] that are able to protect SPIs cells against UV-induced apoptosis.CMfrom SPIs cells lacks this protective activity. However, after heat denaturation CM from SPIs cells regains a protective activity comparable with that of wtNIH3T3 cells. This indicates that CM from SPIs cells contains an antagonistic factor interfering with the anti-apoptotic activity present. SPIsS262A cells do not produce the antagonist suggesting that phosphorylation of Ser-262 is required. Moreover, in line with the apparent lack of anti-apoptotic activity, CM from SPIs cells does not induce the expression of COX-2 or the activation of p42/p44 MAP kinase in SPIs cells. In contrast, CM from wtNIH3T3 and SPIsS262A cells or heat-treated CM from SPIs cells does induce these anti-apoptotic markers. Since we have previously shown that some of the arachidonic acid metabolites present in CM from wtNIH3T3 cells are prostaglandin (PG) E2 and PGF2a, we investigated the effect of these PGs on cell survival. Although PGE2 and PGF2a were found to protect wtNIH3T3 and SPIsS262A cells against UV-induced apoptosis, these PGs failed to rescue SPIs cells. The fact that the concentrations of PGE2 and PGF2a in the CM from SPIs cells and wtNIH3T3 cells were found to be comparable suggests that the failure of these PGs to protect SPIs cells could render these cells more apoptosis sensitive. Concomitantly, upon incubation with PGE2 and PGF2a, an increased expression of COX-2 and activation of p42/p44 MAP kinase were observed in wtNIH3T3 and SPIsS262A cells but not in SPIs cells. Hence, it appears that specific mechanisms of cell survival are impaired in SPIs cells.
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Phosphatidylinositol Transfer Protein expression altered by aging and parkinson disease
Cellular and Molecular Neurobiology, 2006Co-Authors: Malgorzata Chalimoniuk, Gerry T Snoek, Agata Adamczyk, Andrzej Malecki, Joanna B StrosznajderAbstract:1. Phosphatidylinositol Transfer Proteins (PI-TP) are responsible for the transport of Phosphatidylinositol (PI) and other phospholipids from endoplasmic reticulum to the other membranes and indirectly for lipid mediated signaling. Till now little is known about PI-TPs in brain aging and neurodegeneration. The aim of this study was to investigate expression of PI-TP in the brain during aging and in animal's model of Parkinson disease (PD) induced by 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP). Moreover, in vitro, effect of 1-methyl-4-phenyl-pyridine cation (MPP+) on PI-TP, tyrosine hydroxylase (TH) Protein level, and viability of cells was investigated. 2. Wistar rats 4, 24, and 36 months old and C57/BL mice and rat pheochromocytoma (PC12) cell line were used for the studies. Mice C57/BL received three injections of MPTP in saline at 2 h intervals in a total dose of 40 mg/kg and then after 3, 7, and 14 days they were used for the investigation. PC12 cells were treated with increasing concentration (50–300 μM) of MPP+ for 24 h at 37°C. The level of PI-TPα and β and TH were determined using Western Blot analysis. 3. Our data indicated that PI-TPα and β level decreased in brain of 36 months old rat by 20% comparing to the control value (4 months old). In animal's model of PD, PI-TPα and β level was significantly lower by 85, 69, 64% in striatum at 3, 7, and 14 days after MPTP injection, respectively, compared to the control value. MPP+ decreased PI-TPα and β, TH expression, and viability of PC12 cells in a dose-dependent manner. H2O2, menadione, and NO donor significantly decreased the PI-TP level and viability of PC12 cells. 4. Our results indicate the lower Protein expression of PI-TPα and β in aged brain and in PD and suggest that oxidative stress may be responsible for the alteration of PI-TP.
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a Phosphatidylinositol Transfer Protein α dependent survival factor protects cultured primary neurons against serum deprivation induced cell death
Journal of Neurochemistry, 2006Co-Authors: Karel W. A. Wirtz, Martijn Schenning, Hanneke Bunte, Peter Sodaar, Dop P R Bar, Freek L Van Muiswinkel, Gerry T SnoekAbstract:Selective neuronal loss is a prominent feature in both acute and chronic neurological disorders. Recently, a link between neurodegeneration and a deficiency in the lipid transport Protein Phosphatidylinositol Transfer Protein α (PI-TPα) has been demonstrated. In this context it may be of importance that fibroblasts overexpressing PI-TPα are known to produce and secrete bioactive survival factors that protect fibroblasts against UV-induced apoptosis. In the present study it was investigated whether the conditioned medium of cells overexpressing PI-TPα (CMα) has neuroprotective effects on primary neurons in culture. We show that CMα is capable of protecting primary, spinal cord-derived motor neurons from serum deprivation-induced cell death. Since the conditioned medium of wild-type cells was much less effective, we infer that the neuroprotective effect of CMα is linked (in part) to the PI-TPα-dependent production of arachidonic acid metabolites. The neuroprotective activity of CMα is partly inhibited by suramin, a broad-spectrum antagonist of G-Protein coupled receptors. Western blot analysis shows that brain cortex and spinal cord express relatively high levels of PI-TPα, suggesting that the survival factor may be produced in neuronal tissue. We propose that the bioactive survival factor is implicated in neuronal survival. If so, PI-TPα could be a promising target to be evaluated in studies on the prevention and treatment of neurological disorders.
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Phosphatidylinositol Transfer Protein α regulates growth and apoptosis of nih3t3 cells involvement of a cannabinoid 1 like receptor
Journal of Lipid Research, 2004Co-Authors: Martijn Schenning, Karel W. A. Wirtz, Claudia M Van Tiel, Danielle Van Manen, Jord C Stam, Barend M Gadella, Gerry T SnoekAbstract:Mouse fibroblast cells overexpressing Phosphatidylinositol Transfer Protein α [PI-TPα; sense PI-TPα (SPIα) cells] show a significantly increased rate of proliferation and an extreme resistance toward ultraviolet- or tumor necrosis factor-α-induced apoptosis. The conditioned medium (CM) from SPIα cells or the neutral lipid extract from CM stimulated the proliferation of quiescent wild-type NIH3T3 cells. CM was also highly effective in increasing resistance toward induced apoptosis in both wild-type cells and the highly apoptosis-sensitive SPIβ cells (i.e., wild-type cells overexpressing PI-TPβ). CM from SPIα cells grown in the presence of NS398, a specific cyclooxygenase-2 (COX-2) inhibitor, expressed a diminished mitogenic and antiapoptotic activity. This strongly suggests that at least one of the bioactive factor(s) is an eicosanoid. In accordance, SPIα cells express enhanced levels of COX-1 and COX-2. The antiapoptotic activity of CM from SPIα cells tested on SPIβ cells was inhibited by ∼50% by pertussis toxin and suramin as well as by SR141716A, a specific antagonist of the cannabinoid 1 receptor. These inhibitors had virtually no effect on the COX-2-independent antiapoptotic activity of CM from SPIα cells.. The latter results imply that PI-TPα mediates the production of a COX-2-dependent eicosanoid that activates a G-Protein-coupled receptor, most probably a cannabinoid 1-like receptor.
N Q Mcdonald - One of the best experts on this subject based on the ideXlab platform.
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phosphorylation of a distinct structural form of Phosphatidylinositol Transfer Protein α at ser166 by Protein kinase c disrupts receptor mediated phospholipase c signaling by inhibiting delivery of Phosphatidylinositol to membranes
Journal of Biological Chemistry, 2004Co-Authors: C P Morgan, Andrew Ball, Alison Skippen, J Murrayrust, N Q Mcdonald, Victoria Allenbaume, Bruno Segui, Banafshe Larijani, Gopal P Sapkota, Nick MorriceAbstract:Phosphatidylinositol Transfer Protein alpha (PITPalpha) participates in the supply of Phosphatidylinositol ( PI) required for many cellular events including phospholipase C (PLC) beta and gamma signaling by G-Protein-coupled receptors and receptor-tyrosine kinases, respectively. Protein kinase C has been known to modulate PLC signaling by G-Protein-coupled receptors and receptor-tyrosine kinases, although the molecular target has not been identified in most instances. In each case phorbol myristate acetate pretreatment of HL60, HeLa, and COS-7 cells abrogated PLC stimulation by the agonists formyl-Met-Leu-Phe, ATP, and epidermal growth factor, respectively. Here we show that phosphorylation of PITPalpha at Ser(166) resulted in inhibition of receptor-stimulated PLC activity. Ser(166) is localized in a small pocket between the 165 - 172 loop and the rest of the Protein and was not solvent-accessible in either the PI- or phosphatidylcholine-loaded structures of PITPalpha. To allow phosphorylation at Ser(166), a distinct structural form is postulated, and mutation of Thr(59) to alanine shifted the equilibrium to this form, which could be resolved on native PAGE. The elution profile observed by size exclusion chromatography of phosphorylated PITPalpha from rat brain or in vitro phosphorylated PITPalpha demonstrated that phosphorylated PITPalpha is structurally distinct from the non-phosphorylated form. Phosphorylated PITPalpha was unable to deliver its PI cargo, although it could deliver phosphatidylcholine. We conclude that the PITPalpha structure has to relax to allow access to the Ser(166) site, and this may occur at the membrane surface where PI delivery is required for receptor-mediated PLC signaling.
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structure function analysis of human Phosphatidylinositol Transfer Protein alpha bound to Phosphatidylinositol
Structure 12 (2) pp. 317-326. (2004), 2004Co-Authors: Sarah J Tilley, Shamshad Cockcroft, Alison Skippen, J Murrayrust, P M Swigart, Albert E Stewart, C P Morgan, N Q McdonaldAbstract:Phosphatidylinositol Transfer Protein α (PITPα) selectively transports and promotes exchange of Phosphatidylinositol (PI) and phosphatidylcholine (PC) between lipid bilayers. In higher eukaryotes PITPα is required for cellular functions such as phospholipase C-mediated signaling, regulated exocytosis, and secretory vesicle formation. We have determined the crystal structure of human PITPα bound to its physiological ligand, PI, at 2.95 A resolution. The structure identifies the critical side chains within the lipid-headgroup binding pocket that define the exquisite specificity for PI. Mutational analysis of the PI binding pocket is in good agreement with the structural data and allows manipulation of functional properties of PITPα. Surprisingly, there are no major conformational differences between PI- and PC-loaded PITPα, despite previous predictions. In the crystal, PITPα-PI is dimeric, with two identical dimers in the asymmetric unit. The dimer interface masks precisely the sequence we identify as contributing to PITPalpha membrane interaction. Our structure represents a soluble, transport-competent form of PI-loaded PITPalpha.
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structure function analysis of human corrected Phosphatidylinositol Transfer Protein alpha bound to Phosphatidylinositol
Structure, 2004Co-Authors: Sarah J Tilley, Shamshad Cockcroft, Alison Skippen, J Murrayrust, P M Swigart, Albert E Stewart, C P Morgan, N Q McdonaldAbstract:Phosphatidylinositol Transfer Protein α (PITPα) selectively transports and promotes exchange of Phosphatidylinositol (PI) and phosphatidylcholine (PC) between lipid bilayers. In higher eukaryotes PITPα is required for cellular functions such as phospholipase C-mediated signaling, regulated exocytosis, and secretory vesicle formation. We have determined the crystal structure of human PITPα bound to its physiological ligand, PI, at 2.95 A resolution. The structure identifies the critical side chains within the lipid-headgroup binding pocket that define the exquisite specificity for PI. Mutational analysis of the PI binding pocket is in good agreement with the structural data and allows manipulation of functional properties of PITPα. Surprisingly, there are no major conformational differences between PI- and PC-loaded PITPα, despite previous predictions. In the crystal, PITPα-PI is dimeric, with two identical dimers in the asymmetric unit. The dimer interface masks precisely the sequence we identify as contributing to PITPα membrane interaction. Our structure represents a soluble, transport-competent form of PI-loaded PITPα.