共查询到20条相似文献,搜索用时 31 毫秒
1.
Chemin J Patel AJ Duprat F Sachs F Lazdunski M Honore E 《Pflügers Archiv : European journal of physiology》2007,455(1):97-103
TREK-1 is an unconventional K+ channel that is activated by both physical and chemical stimuli. In this study, we show that the inner leaflet membrane phospholipids,
including PIP2, exert a mixed stimulatory and inhibitory effect on TREK-1. Intra-cellular phospholipids inhibit basal channel activity and
activation by membrane stretch, intra-cellular acidosis and arachidonic acid. However, binding of endogenous negative inner
leaflet phospholipids with poly-lysine reduces inhibition and reveals channel stimulation by exogenous intra-cellular phospholipids.
A similar effect is observed with PI, PE, PS and PA, unlike DG, demonstrating that the phosphate at position 3 is required
although the global charge of the molecule is not critical. Inhibition depends on the distal C-terminal domain that conditions
channel mechano-sensitivity, but is independent of the positively charged PIP2 stimulatory site in the proximal C-terminal domain. This is, to our knowledge, the first report of an ion channel dually
regulated by membrane phospholipids. 相似文献
2.
Na+, K+-ATPase is one of major membrane proteins that has two subunits, alpha and beta. The alpha subunit has the ATPase activity and the ouabain binding site. Among four isoforms of the alpha subunit, expression of alpha1, alpha2, and alpha3, but not alpha4, is observed in matured rat brain. Ouabain is one of cardiac glycosides, and endogenous ouabain-like compounds have been recognized as a new class of steroid hormone. The alpha subunit is considered as their endogenous receptor. Recent studies envisaged the importance of membrane microdomains (MDs) as signaling platforms, which are recovered as a detergent-resistant membrane microdomain fraction (DRM). Although this ATPase has been considered as a non-DRM protein, some amount of the alpha subunit was found to be a component of the DRM prepared from the synaptic plasma membrane fraction (SPM) of rat brain. Ouabain treatment increased the amount of alpha3 isoform, but not alpha1, in the DRM derived from synaptosome fraction and SPM. These results suggest that the localization of the alpha subunit of Na+, K+-ATPase is regulated with isoform-specific mechanisms and the physiological importance of DRM in the signal transduction of the endogenous ouabain-like steroid hormone in neurons. 相似文献
3.
Diomedes E. Logothetis Vasileios I. Petrou Scott K. Adney Rahul Mahajan 《Pflügers Archiv : European journal of physiology》2010,460(2):321-341
The plasma membrane phosphoinositide phosphatidylinositol 4,5-bisphosphate (PIP2) controls the activity of most ion channels tested thus far through direct electrostatic interactions. Mutations in channel proteins that change their apparent affinity to PIP2 can lead to channelopathies. Given the fundamental role that membrane phosphoinositides play in regulating channel activity, it is surprising that only a small number of channelopathies have been linked to phosphoinositides. This review proposes that for channels whose activity is PIP2-dependent and for which mutations can lead to channelopathies, the possibility that the mutations alter channel-PIP2 interactions ought to be tested. Similarly, diseases that are linked to disorders of the phosphoinositide pathway result in altered PIP2 levels. In such cases, it is proposed that the possibility for a concomitant dysregulation of channel activity also ought to be tested. The ever-growing list of ion channels whose activity depends on interactions with PIP2 promises to provide a mechanism by which defects on either the channel protein or the phosphoinositide levels can lead to disease. 相似文献
4.
Logothetis DE Jin T Lupyan D Rosenhouse-Dantsker A 《Pflügers Archiv : European journal of physiology》2007,455(1):83-95
Phosphoinositides, such as phosphatidylinositol-bisphosphate (PIP2), control the activity of many ion channels in yet undefined ways. Inwardly, rectifying potassium (Kir) channels were the
first shown to be dependent on direct interactions with phosphoinositides. Alterations in channel-PIP2 interactions affect Kir single-channel gating behavior. Aberrations in channel-PIP2 interactions can lead to human disease. As the activity of all Kir channels depends on their interactions with phosphoinositides,
future research will aim to understand the molecular events that occur from phosphoinositide binding to channel gating. The
determination of atomic resolution structures for several mammalian and bacterial Kir channels provides great promise towards
this goal. We have mapped onto the three-dimensional channel structure the position of basic residues identified through mutagenesis
studies that contribute to the sensitivity of a Kir channel to PIP2. The localization of these putative PIP2-interacting residues relative to the channel’s permeation pathway has given rise to a testable model, which could account
for channel activation by PIP2. 相似文献
5.
T. Meyer P. von Wichert D. Weins 《Journal of molecular medicine (Berlin, Germany)》1989,67(3):113-118
Summary Two methods of phospholipase A2 determination using14C-labelledE. coli bacterias as substrate were compared. One method works with a filter membrane for separation of cleaved14C-oleate from remaining phospholipids, the other uses the well-known thin-layer chromatography for lipid analysis. Some features of human serum phospholipase A2 regarding pH and Ca2+ dependency were investigated. Possible sources of errors were discussed. It was shown that either method can differentiate between normal and pathologically elevated phospholipase A2 levels, but that the filter method is superior in terms of sensitivity and workload.Abbreviations PLA2
phospholipase A2
- BSA
bovine serum albumin
- (F)FA
(free) fatty acid
- TLC
thin-layer chromatography 相似文献
6.
Some ion channels are regulated by inositol phospholipids and by the products of cleavage by phospholipase C (PLC). KCNQ channels
(Kv7) require membrane phosphatidylinositol 4,5-bisphosphate (PIP2) and are turned off when muscarinic receptors stimulate cleavage of PIP2 by PLC. We test whether diacylglycerols are also important in the regulation of KCNQ2/KCNQ3 channels using electrophysiology
and fluorescent translocation probes as indicators for PIP2 and diacylglycerol in tsA cells. The cells are transfected with M1 muscarinic receptors, channel subunits, and translocation probes. Although they cause translocation of a fluorescent probe
with a diacylglycerol-binding C1 domain, exogenously applied diacylglycerol (oleoyl-acetyl-glycerol and dioctanoyl glycerol)
and phorbol ester do not mimic or occlude the suppression of KCNQ current by muscarinic agonist. Blocking the metabolism of
endogenous diacylglycerol by inhibiting diacylglycerol kinase with R59022 or R59949 slows the decay of diacylglycerol twofold
but does not mimic or occlude muscarinic regulation and recovery of current. Blocking diacylglycerol lipase with RHC-80267
also does not occlude muscarinic modulation of current. We conclude that the diacylglycerol produced during activation of
PLC, any activation of protein kinase C that it may stimulate, and downstream products of its metabolism are not essential
players in the acute muscarinic modulation of KCNQ channels. 相似文献
7.
Regulation of TRP channels by PIP2 总被引:3,自引:2,他引:1
Rohacs T 《Pflügers Archiv : European journal of physiology》2007,453(6):753-762
Transient receptor potential (TRP) channels are regulated by a wide variety of physical and chemical factors. Recently, several
members of the TRP channel family were reported to be regulated by phosphatidylinositol 4,5-bisphosphate (PtdIns(4,5)P2, PIP2). This review will summarize the current knowledge on PIP2 regulation of TRP channels and discuss the possibility that PIP2 is a common regulator of mammalian TRP channels. 相似文献
8.
Recent findings have revealed a pivotal role for phospholipids phosphatidylinositol -4,5-biphosphate (PIP2) and phosphatidylinositol -3,4,5-trisphosphate (PIP3) in the regulation of high voltage-activated (HVA) Ca2+ channels. PIP2 exerts two opposing actions on HVA Ca2+ channels: It stabilizes their activity but also produces a voltage-dependent inhibition that can be antagonized by protein
kinase A (PKA) phosphorylation. PIP2 depletion and arachidonic acid together mediate the slow, voltage-independent inhibition of HVA Ca2+ channels by G
q/11
-coupled receptors in neurons. A sufficient level of plasma membrane PIP2 also appears to be necessary for G
βγ
-mediated inhibition. On the other hand, increased production of PIP3 by PI-3 kinases promotes trafficking of HVA Ca2+ channels to the plasma membrane. This review discusses these findings and their implications. 相似文献
9.
Dawn Su-Yin Yeo Gaie Brown Richard Sutejo Boon-Huan Tan Richard J. Sugrue 《Virology》2009,386(1):168-213
We examined the structure of lipid-raft membranes in respiratory syncytial virus infected cells. Cholesterol depletion studies using methyl-β-cyclodextrin suggested that membrane cholesterol was required for virus filament formation, but not inclusion bodies. In addition, virus filament formation coincided with elevated 3-hydroxy-3-methylglutaryl-coenzyme A reductase expression, suggesting an increase in requirement for endogenous cholesterol synthesis during virus assembly. Lipid raft membranes were examined by mass spectrometry, which suggested that virus infection induced subtle changes in the lipid composition of these membrane structures. This analysis revealed increased levels of raft-associated phosphatidylinositol (PI) and phosphorylated PI during RSV infection, which correlated with the appearance of phosphatidylinositol 4,5-bisphosphate and phosphatidylinositol 3,4,5-triphosphate (PIP3) within virus inclusion bodies, and inhibiting the synthesis of PIP3 impaired the formation of progeny virus. Collectively, our analysis suggests that RSV infection induces specific changes in the composition of raft-associated lipids, and that these changes play an important role in virus maturation. 相似文献
10.
Hofgaard JP Banach K Mollerup S Jørgensen HK Olesen SP Holstein-Rathlou NH Nielsen MS 《Pflügers Archiv : European journal of physiology》2008,457(2):303-313
Changes in the lipid composition of cardiac myocytes have been reported during cardiac hypertrophy, cardiomyopathy, and infarction.
Because a recent study indicates a relation between low phosphatidylinositol-bisphosphate (PIP2) levels and reduced intercellular coupling, we tested the hypothesis that agonist-induced changes in PIP2 can result in a reduction of the functional coupling of cardiomyocytes and, consequently, in changes in conduction velocity.
Intercellular coupling was measured by Lucifer Yellow dye transfer in cultured neonatal rat cardiomyocytes. Conduction velocity
was measured in cardiomyocytes grown on microelectrode arrays. Intercellular coupling was reduced by angiotensin II (43.7 ± 9.3%,
N = 11) and noradrenaline (58.0 ± 10.7%, N = 11). To test if reduced intercellular coupling after agonist stimulation was caused by PIP2-depletion, myocytes were stimulated by angiotensin II (57.3 ± 5.7%, N = 14) and then allowed to recover in medium with or without wortmannin (an inhibitor of PIP2 synthesis). Intercellular coupling fully recovered in control medium (102.1 ± 8.9%, N = 10), whereas no recovery occurred in the presence of wortmannin (69.3 ± 7.8%, N = 12). Inhibition of PKC, calmodulin, or arachidonic acid production did not affect the response to either angiotensin II
or noradrenaline. Furthermore, decreasing or increasing PIP2 also decreased and increased intercellular coupling, respectively. This supports the role of PIP2 in the regulation of intercellular coupling. In beating myocytes, conduction velocity was reduced by angiotensin II stimulation,
and recovery after wash out was prevented by inhibition of PIP2 production. Reductions in PIP2 inhibit intercellular coupling in cardiomyocytes, and stimulation by physiologically relevant agonists reduces intercellular
coupling by this mechanism. The reduction in intercellular coupling lowered conduction velocity. 相似文献
11.
Phosphatidylinositol (4,5)-bisphosphate (PIP2) is an important lipid mediator that has multiple regulatory functions. There is now increasing evidence that the phosphatidylinositol
4-phosphate 5 kinases (PIP5Ks), which synthesize PIP2, are regulated spatially and temporally and that they have isoform-specific functions and regulations. This review will summarize
the highlights of recent developments in understanding how the three major PIP5K isoforms regulate the actin cytoskeleton
and other important cellular processes. 相似文献
12.
Trebak M Lemonnier L DeHaven WI Wedel BJ Bird GS Putney JW 《Pflügers Archiv : European journal of physiology》2009,457(4):757-769
The canonical transient receptor potential (TRPC) proteins have been recognized as key players in calcium entry pathways activated
through phospholipase-C-coupled receptors. While it is clearly demonstrated that members of the TRPC3/6/7 subfamily are activated
by diacylglycerol, the mechanism by which phospholipase C activates members of the TRPC1/4/5 subfamily remains a mystery.
In this paper, we provide evidence for both negative and positive modulatory roles for membrane polyphosphoinositides in the
regulation of TRPC5 channels. Depletion of polyphosphatidylinositol 4-phosphate and phosphatidylinositol 4,5-bisphosphate
(PIP2) through inhibition of phosphatidylinositol 4-kinase activates calcium entry and membrane currents in TRPC5-expressing but
not in TRPC3- or TRPC7-expressing cells. Inclusion of polyphosphatidylinositol 4-phosphate or PIP2, but not phosphatidylinositol 3,4,5-trisphosphate, in the patch pipette inhibited TRPC5 currents. Paradoxically, depletion
of PIP2 with a directed 5-phosphatase strategy inhibited TRPC5. Furthermore, when the activity of single TRPC5 channels was examined
in excised patches, the channels were robustly activated by PIP2. These findings indicate complex functions for regulation of TRPC5 by PIP2, and we propose that membrane polyphosphoinositides may have at least two distinct functions in regulating TRPC5 channel
activity.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.
Mohamed Trebak and Loic Lemonnier contributed equally to this work. 相似文献
13.
This review summarizes the modulation of transient receptor potential (TRP) channels, by phosphoinositides. TRP channels are
characterized by polymodal activation and a surprising complexity of regulation mechanisms. Possibly, most if not all TRP
channels are modulated by phosphoinositides. Modulation by phosphatidylinositol 4,5-biphosphate (PIP2) has been shown in detail for TRP vanilloid (TRPV) 1, TRPV5, TRP melastatin (TRPM) 4, TRPM5, TRPM7, TRPM8, TRP polycystin
2, and the Drosophila TPR-like (TRPL) channels. This review describes mechanisms of modulation of TRP channels mainly by PIP2 and discusses some future challenges of this fascinating topic. 相似文献
14.
Junghwa Lim Ming Zhou Timothy D. Veenstra Deborah K. Morrison 《Genes & development》2010,24(14):1496-1506
Protein scaffolds play an important role in signal transduction, regulating the localization of signaling components and mediating key protein interactions. Here, we report that the major binding partners of the Connector Enhancer of KSR 1 (CNK1) scaffold are members of the cytohesin family of Arf guanine nucleotide exchange factors, and that the CNK1/cytohesin interaction is critical for activation of the PI3K/AKT cascade downstream from insulin and insulin-like growth factor 1 (IGF-1) receptors. We identified a domain located in the C-terminal region of CNK1 that interacts constitutively with the coiled-coil domain of the cytohesins, and found that CNK1 facilitates the membrane recruitment of cytohesin-2 following insulin stimulation. Moreover, through protein depletion and rescue experiments, we found that the CNK1/cytohesin interaction promotes signaling from plasma membrane-bound Arf GTPases to the phosphatidylinositol 4-phosphate 5-kinases (PIP5Ks) to generate a PIP2-rich microenvironment that is critical for the membrane recruitment of insulin receptor substrate 1 (IRS1) and signal transmission to the PI3K/AKT cascade. These findings identify CNK1 as a new positive regulator of insulin signaling. 相似文献
15.
Hilgemann DW 《Pflügers Archiv : European journal of physiology》2007,455(1):55-67
PIP2 is a minor phospholipid that modulates multiple cellular processes. However, its abundance by mass, like diacylglycerol,
is still 20 to 100 times greater than the master phospholipid second messenger, PIP3. Therefore, it is a case-by-case question whether PIP2 is acting more like GTP, in being a cofactor in regulatory processes, or whether it is being used as a true second messenger.
Analysis of signaling mechanisms in primary cells is essential to answer this question, as overexpression studies will naturally
generate false positives. In connection with the possible messenger function of PIP2, a second question arises as to how and if PIP2 metabolism and signaling may be limited in space. This review summarizes succinctly the notable cases in which PIP2 is proposed to function in a localized way and the different mechanistic models that may allow it to function locally. In
general, drastic restrictions of PIP2 diffusion are required. It is speculated that molecular PIP2 signaling may be possible in the absence of PIP2 gradients via ternary complexes between PIP2 and two protein partners. That PIP2 synthesis and hydrolysis might be locally dependent on protein–protein interactions, and direct lipid “hand-off” is suggested
by multiple results. 相似文献
16.
Yangong Liu Tomohiro Iwano Fangfang Ma Pu Wang Yan Wang Mingqi Zheng Gang Liu Katsushige Ono 《Pathophysiology》2019,26(1):31-38
T-type calcium (Ca2+) channels play important physiological functions in excitable cells including cardiomyocyte. Phosphatidylinositol-4,5-bisphosphate (PIP2) has recently been reported to modulate various ion channels’ function. However the actions of PIP2 on the T-type Ca2+ channel remain unclear. To elucidate possible effects of PIP2 on the T-type Ca2+ channel, we applied patch clamp method to investigate recombinant CaV3.1- and CaV3.2-T-type Ca2+ channels expressed in mammalian cell lines with PIP2 in acute- and long-term potentiation. Short- and long-term potentiation of PIP2 shifted the activation and the steady-state inactivation curve toward the hyperpolarization direction of CaV3.1-ICa.T without affecting the maximum inward current density. Short- and long-term potentiation of PIP2 also shifted the activation curve toward the hyperpolarization direction of CaV3.2-ICa.T without affecting the maximum inward current density. Conversely, long-term but not short-term potentiation of PIP2 shifted the steady-state inactivation curve toward the hyperpolarization direction of CaV3.2-ICa.T. Long-term but not short-term potentiation of PIP2 blunted the voltage-dependency of current decay CaV3.1-ICa.T. PIP2 modulates CaV3.1- and CaV3.2-ICa.T not by their current density but by their channel gating properties possibly through its membrane-delimited actions. 相似文献
17.
Multiple forms of phosphatidylinositol are generated by differential phosphorylation of the inositol headgroup. These phosphoinositides, specifically PI(4,5)P2, have been implicated as modulators in a variety of transport processes. The data indicate that phosphoinositides can modulate transporters directly or via the activation of down-stream signaling components. The phosphoinositide pathway has been linked to changes in transporter kinetics, intracellular signaling, membrane targeting and membrane stability. Recent results obtained for several of the well-characterized transport systems suggest the need to reassess the role of PI(4,5)P2 and question whether lower abundance forms of the phosphoinositides, notably PI(3,4,5)P3 (PIP3) and PI(3,4)P2, are the pertinent transport regulators. In contrast to PI(4,5)P2, these latter forms represent a dynamic, regulated pool, the characteristics of which are more compatible with the nature of signaling intermediates. A recently described, novel transepithelial signaling pathway has been demonstrated for PIP3 in which a signal initiated on the basolateral membrane is transduced to the apical membrane entirely within the planar face of the inner leaflet of the plasma membrane. The new paradigms emerging from recent studies may be widely applicable to transporter regulation in other cell types and are particularly relevant for signaling in polarized cells. 相似文献
18.
The Golgi complex plays a key role in cholesterol trafficking in cells. Our earlier study demonstrated amyloid β-protein (Aβ) alters cholesterol distribution and abundance in the Golgi complex of astrocytes. We now test the hypothesis that the Aβ-induced increase in Golgi complex cholesterol is due to retrograde movement of the cholesterol carrier protein caveolin-1 from the cell plasma membrane to the Golgi complex in astrocytes. Results with mouse primary astrocytes indicated that Aβ1-42-induced increase in cholesterol and caveolin abundance in the Golgi complex was accompanied by a reduction in cholesterol and caveolin levels in the plasma membrane. Transfected rat astrocytes (DITNC1) with siRNA directed at caveolin-1 mRNA inhibited the Aβ1-42-induced redistribution of both cholesterol and caveolin from the plasma membrane to the Golgi complex. In astrocytes not treated with Aβ1-42, suppression of caveolin-1 expression also significantly reduced cholesterol abundance in the Golgi complex, further demonstrating the role for caveolin in retrograde transport of cholesterol from the plasma membrane to the Golgi complex. Perturbation of this process by Aβ1-42 could have consequences on membrane structure and cellular functions requiring optimal levels of cholesterol. 相似文献
19.
Tinya C. Fleming Jae Yen Shin Sang-Hyuk Lee Eric Becker Kerwyn Casey Huang Carlos Bustamante Kit Pogliano 《Genes & development》2010,24(11):1160-1172
SpoIIIE is an FtsK-related protein that transports the forespore chromosome across the Bacillus subtilis sporulation septum. We use membrane photobleaching and protoplast assays to demonstrate that SpoIIIE is required for septal membrane fission in the presence of trapped DNA, and that DNA is transported across separate daughter cell membranes, suggesting that SpoIIIE forms a channel that partitions the daughter cell membranes. Our results reveal a close correlation between septal membrane fission and the assembly of a stable SpoIIIE translocation complex at the septal midpoint. Time-lapse epifluorescence, total internal reflection fluorescence (TIRF) microscopy, and live-cell photoactivation localization microscopy (PALM) demonstrate that the SpoIIIE transmembrane domain mediates dynamic localization to active division sites, whereas the assembly of a stable focus also requires the cytoplasmic domain. The transmembrane domain fails to completely separate the membrane, and it assembles unstable foci. TIRF microscopy and biophysical modeling of fluorescence recovery after photobleaching (FRAP) data suggest that this unstable protein transitions between disassembled and assembled oligomeric states. We propose a new model for the role of SpoIIIE assembly in septal membrane fission that has strong implications for how the chromosome terminus crosses the septum. 相似文献
20.
Epelman S Berenger B Stack D Neely GG Ma LL Mody CH 《American journal of respiratory cell and molecular biology》2008,39(6):657-665
Patients with cystic fibrosis suffer recurrent pulmonary infections that are characterized by an overactive yet ineffective and destructive inflammatory response that is associated with respiratory infections by Pseudomonas aeruginosa, a pathogen that produces a number of phlogistic molecules. To better understand this process, we used exoenzyme S (ExoS), one of the key P. aeruginosa-secreted exoproducts, which is known to stimulate cells via the Toll-like receptor (TLR) pathway. We found that ExoS induced proinflammatory cytokine production via the NF-kappaB, Erk1/2, and Src kinase pathways. Because Src kinases are concentrated within cholesterol-containing, detergent-resistant membrane microdomains (DRM) (also called lipid rafts) and DRM act as signaling platforms and amplifiers on the surface of cells, we addressed the role of DRM in ExoS signaling. ExoS bound directly to a subset of DRM and induced the phosphorylation of multiple proteins within DRM, including Src kinases. Disruption of DRM by cholesterol extraction prevented NF-kappaB and Erk 1/2 activation and TNF-alpha production in response to ExoS. Activation of monocytic cells by other TLR and Nod-like receptor agonists, such as lipoteichoic acid, lipopolysaccharide, and peptidoglycan, were also dependent on DRM, and disruption prevented TNF-alpha production. Disruption of DRM did not prevent ExoS binding but did release the Src kinase, Lyn, from the DRM fraction into the detergent-soluble fraction, a site in which Src kinases are not active. These studies show that ExoS, a TLR agonist, requires direct binding to DRM for optimal signaling, which suggests that DRM are possible therapeutic targets in cystic fibrosis. 相似文献