Defining how multiple lipid species interact with inward rectifier potassium (Kir2) channels

Protein–lipid interactions are a key element of the function of many integral membrane proteins. These potential interactions should be considered alongside the complexity and diversity of membrane lipid composition. Inward rectifier potassium channel (Kir) Kir2.2 has multiple interactions with plasma membrane lipids: Phosphatidylinositol (4, 5)-bisphosphate (PIP2) activates the channel; a secondary anionic lipid site has been identified, which augments the activation by PIP2; and cholesterol inhibits the channel. Molecular dynamics simulations are used to characterize in molecular detail the protein–lipid interactions of Kir2.2 in a model of the complex plasma membrane. Kir2.2 has been simulated with multiple, functionally important lipid species. From our simulations we show that PIP2interacts most tightly at the crystallographic interaction sites, outcompeting other lipid species at this site. Phosphatidylserine (PS) interacts at the previously identified secondary anionic lipid interaction site, in a PIP2concentration-dependent manner. There is interplay between these anionic lipids: PS interactions are diminished when PIP2is not present in the membrane, underlining the need to consider multiple lipid species when investigating protein–lipid interactions.

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Oligomerization and Ca2+/calmodulin control binding of the ER Ca2+-sensors STIM1 and STIM2 to plasma membrane lipids

Bioscience Reports ◽

10.1042/bsr20130089 ◽

2013 ◽

Vol 33 (5) ◽

Cited By ~ 30

Author(s):

Rajesh Bhardwaj ◽

Hans-Michael Müller ◽

Walter Nickel ◽

Matthias Seedorf

Keyword(s):

Plasma Membrane ◽

Membrane Lipids ◽

Lipid Binding ◽

Dependent Manner ◽

Activation Threshold ◽

Concentration Dependent Manner ◽

Rich Domain ◽

Α Helix ◽

Distinct Features ◽

Ca2 Channels

Ca2+ (calcium) homoeostasis and signalling rely on physical contacts between Ca2+ sensors in the ER (endoplasmic reticulum) and Ca2+ channels in the PM (plasma membrane). STIM1 (stromal interaction molecule 1) and STIM2 Ca2+ sensors oligomerize upon Ca2+ depletion in the ER lumen, contact phosphoinositides at the PM via their cytosolic lysine (K)-rich domains, and activate Ca2+ channels. Differential sensitivities of STIM1 and STIM2 towards ER luminal Ca2+ have been studied but responses towards elevated cytosolic Ca2+ concentration and the mechanism of lipid binding remain unclear. We found that tetramerization of the STIM1 K-rich domain is necessary for efficient binding to PI(4,5)P2-containing PM-like liposomes consistent with an oligomerization-driven STIM1 activation. In contrast, dimerization of STIM2 K-rich domain was sufficient for lipid binding. Furthermore, the K-rich domain of STIM2, but not of STIM1, forms an amphipathic α-helix. These distinct features of the STIM2 K-rich domain cause an increased affinity for PI(4,5)P2, consistent with the lower activation threshold of STIM2 and a function as regulator of basal Ca2+ levels. Concomitant with higher affinity for PM lipids, binding of CaM (calmodulin) inhibited the interaction of the STIM2 K-rich domain with liposomes in a Ca2+ and PI(4,5)P2 concentration-dependent manner. Therefore we suggest that elevated cytosolic Ca2+ concentration down-regulates STIM2-mediated ER–PM contacts via CaM binding.

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Domain architecture of the smooth-muscle plasma membrane: regulation by annexins

Biochemical Journal ◽

10.1042/bj20041363 ◽

2005 ◽

Vol 387 (2) ◽

pp. 309-314 ◽

Cited By ~ 47

Author(s):

Annette DRAEGER ◽

Susan WRAY ◽

Eduard B. BABIYCHUK

Keyword(s):

Smooth Muscle ◽

Plasma Membrane ◽

Membrane Lipids ◽

Domain Architecture ◽

Focal Adhesions ◽

Membrane Lipid ◽

Dependent Manner ◽

Detailed Structural Analysis ◽

Specific Subset ◽

Associated Proteins

Individual signalling events are processed in distinct, spatially segregated domains of the plasma membrane. In a smooth muscle, the sarcolemma is divided into domains of focal adhesions alternating with caveolae-rich zones, both harbouring a specific subset of membrane-associated proteins. Recently, we have demonstrated that the sarcolemmal lipids are similarly segregated into domains of cholesterol-rich lipid rafts and glycerophospholipid-rich non-raft regions. In the present study, we provide a detailed structural analysis of the relationship between these proteinaceous and lipid domains. We demonstrate that the segregation of plasmalemmal protein constituents is intimately linked to that of the membrane lipids. Our results imply that lipid segregation is critical for the preservation of membrane protein architecture and essential for directional translocation of proteins to the sarcolemma. We show that the membrane lipid segregation is supported by the annexin protein family in a Ca2+-dependent manner. Eukaryotic cells harbour numerous, tissue-specific subsets of annexins. By examining the significance of this variety in a smooth muscle, we demonstrate that four different annexins target membrane sites of distinct lipid composition and that each annexin requires a different [Ca2+] for its translocation to the sarcolemma. Our results suggest that the interactions of annexins with distinct plasma membrane regions promote membrane segregation and, in combination with their individual Ca2+ sensitivity, might allow a spatially confined, graded response to a multitude of extra- or intracellular stimuli.

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Criticality of plasma membrane lipids reflects activation state of macrophage cells

10.1101/680157 ◽

2019 ◽

Author(s):

Eugenia Cammarota ◽

Chiara Soriani ◽

Raphaelle Taub ◽

Fiona Morgan ◽

Jiro Sakai ◽

...

Keyword(s):

Plasma Membrane ◽

Critical Point ◽

Membrane Lipids ◽

Membrane Lipid ◽

Membrane Receptors ◽

Critical Conditions ◽

Membrane Composition ◽

Macrophage Cells ◽

Lipid Species ◽

Anti Inflammatory

AbstractSignalling is of particular importance in immune cells, and upstream in the signalling pathway many membrane receptors are functional only as complexes, co-locating with particular lipid species. Work over the last 15 years has shown that plasma membrane lipid composition is close to a critical point of phase separation, with evidence that cells adapt their composition in ways that alter the proximity to this thermodynamical point. Macrophage cells are a key component of the innate immune system, responsive to infections, regulating the local state of inflammation. We investigate changes in the plasma membrane’s proximity to the critical point, as a response to stimulation by various pro- and anti-inflammatory agents. Pro-inflammatory (IFN-γ, Kdo-LipidA, LPS) perturbations induce an increase in the transition temperature of the GMPVs; anti-inflammatory IL4 has the opposite effect. These changes recapitulate complex plasma membrane composition changes, and are consistent with lipid criticality playing a master regulatory role: being closer to critical conditions increases membrane protein activity.

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Lipid Remodeling Confers Osmotic Stress Tolerance to Embryogenic Cells during Cryopreservation

International Journal of Molecular Sciences ◽

10.3390/ijms22042174 ◽

2021 ◽

Vol 22 (4) ◽

pp. 2174

Author(s):

Liang Lin ◽

Junchao Ma ◽

Qin Ai ◽

Hugh W. Pritchard ◽

Weiqi Li ◽

...

Keyword(s):

Lipid Metabolism ◽

Technology Development ◽

Membrane Lipids ◽

Species Conservation ◽

Membrane Lipid ◽

Cell Integrity ◽

Embryogenic Cells ◽

Osmotic Stress Tolerance ◽

Lipid Species ◽

Magnolia Officinalis

Plant species conservation through cryopreservation using plant vitrification solutions (PVS) is based in empiricism and the mechanisms that confer cell integrity are not well understood. Using ESI-MS/MS analysis and quantification, we generated 12 comparative lipidomics datasets for membranes of embryogenic cells (ECs) of Magnolia officinalis during cryogenic treatments. Each step of the complex PVS-based cryoprotocol had a profoundly different impact on membrane lipid composition. Loading treatment (osmoprotection) remodeled the cell membrane by lipid turnover, between increased phosphatidic acid (PA) and phosphatidylglycerol (PG) and decreased phosphatidylcholine (PC) and phosphatidylethanolamine (PE). The PA increase likely serves as an intermediate for adjustments in lipid metabolism to desiccation stress. Following PVS treatment, lipid levels increased, including PC and PE, and this effectively counteracted the potential for massive loss of lipid species when cryopreservation was implemented in the absence of cryoprotection. The present detailed cryobiotechnology findings suggest that the remodeling of membrane lipids and attenuation of lipid degradation are critical for the successful use of PVS. As lipid metabolism and composition varies with species, these new insights provide a framework for technology development for the preservation of other species at increasing risk of extinction.

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Impact of Membrane Lipids on UapA and AzgA Transporter Subcellular Localization and Activity in Aspergillus nidulans

Journal of Fungi ◽

10.3390/jof7070514 ◽

2021 ◽

Vol 7 (7) ◽

pp. 514

Author(s):

Mariangela Dionysopoulou ◽

George Diallinas

Keyword(s):

Plasma Membrane ◽

Subcellular Localization ◽

Aspergillus Nidulans ◽

Membrane Lipids ◽

Membrane Lipid ◽

Lipid Biosynthesis ◽

Transport Kinetics ◽

Negative Effect ◽

And Function

Recent biochemical and biophysical evidence have established that membrane lipids, namely phospholipids, sphingolipids and sterols, are critical for the function of eukaryotic plasma membrane transporters. Here, we study the effect of selected membrane lipid biosynthesis mutations and of the ergosterol-related antifungal itraconazole on the subcellular localization, stability and transport kinetics of two well-studied purine transporters, UapA and AzgA, in Aspergillus nidulans. We show that genetic reduction in biosynthesis of ergosterol, sphingolipids or phosphoinositides arrest A. nidulans growth after germling formation, but solely blocks in early steps of ergosterol (Erg11) or sphingolipid (BasA) synthesis have a negative effect on plasma membrane (PM) localization and stability of transporters before growth arrest. Surprisingly, the fraction of UapA or AzgA that reaches the PM in lipid biosynthesis mutants is shown to conserve normal apparent transport kinetics. We further show that turnover of UapA, which is the transporter mostly sensitive to membrane lipid content modification, occurs during its trafficking and by enhanced endocytosis, and is partly dependent on autophagy and Hect-type HulARsp5 ubiquitination. Our results point out that the role of specific membrane lipids on transporter biogenesis and function in vivo is complex, combinatorial and transporter-dependent.

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Inhibition of Na+/Ca2+ exchange in renal BLMV by IP3 depends on site of action and direction of Ca2+ flux

AJP Renal Physiology ◽

10.1152/ajprenal.1994.266.5.f785 ◽

1994 ◽

Vol 266 (5) ◽

pp. F785-F790 ◽

Cited By ~ 1

Author(s):

C. L. Fraser ◽

C. Cummings ◽

G. Cassafer

Keyword(s):

Plasma Membrane ◽

Basolateral Membrane ◽

Membrane Vesicles ◽

Dependent Manner ◽

The Novel ◽

Concentration Dependent Manner ◽

Site Of Action ◽

Brain Synaptosomes ◽

Membrane Bound ◽

Inside Out

It has previously been shown in synaptosomes that inositol 1,4,5-trisphosphate (1,4,5-IP3) inhibits Ca2+ transport by the plasma membrane-bound Na+/Ca2+ exchanger. The present study was therefore designed to determine if the effect of 1,4,5-IP3 was dependent on its site of action at the plasma membrane or on the direction of Ca2+ flux. To investigate this possibility, studies were performed in basolateral membrane vesicles (BLMV) isolated from rat renal cortex. As with synaptosomes, Ca2+ transport was inhibited by 1,4,5-IP3 in a concentration-dependent manner. At a concentration of 10(-6) M, 1,4,5-IP3 significantly (P < 0.005) inhibited Ca2+ transport by 36%. When Ca2+ transport was carried out in inside-out vesicles, 10(-6) M 1,4,5-IP3 significantly (P < 0.002) increased the degree of inhibition by an additional 75% (63 vs. 36%). However, 1,4,5-IP3 had no significant effect on Ca2+ transport in inside-out vesicles when Ca2+ flux was reversed (i.e., Ca2+ efflux). These data in renal BLMV confirm the novel action of 1,4,5-IP3 on the Na+/Ca2+ exchanger previously described in brain synaptosomes. These results also suggest that the action of 1,4,5-IP3 depends on both its site of action at the plasma membrane and on the direction of Ca2+ flux.

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Criticality of plasma membrane lipids reflects activation state of macrophage cells

Journal of The Royal Society Interface ◽

10.1098/rsif.2019.0803 ◽

2020 ◽

Vol 17 (163) ◽

pp. 20190803 ◽

Cited By ~ 1

Author(s):

Eugenia Cammarota ◽

Chiara Soriani ◽

Raphaelle Taub ◽

Fiona Morgan ◽

Jiro Sakai ◽

...

Keyword(s):

Plasma Membrane ◽

Critical Point ◽

Membrane Lipids ◽

Membrane Receptors ◽

Interleukin 4 ◽

Critical Conditions ◽

Membrane Composition ◽

Macrophage Cells ◽

Lipid Species ◽

Anti Inflammatory

Signalling is of particular importance in immune cells, and upstream in the signalling pathway many membrane receptors are functional only as complexes, co-locating with particular lipid species. Work over the last 15 years has shown that plasma membrane lipid composition is close to a critical point of phase separation, with evidence that cells adapt their composition in ways that alter the proximity to this thermodynamic point. Macrophage cells are a key component of the innate immune system, are responsive to infections and regulate the local state of inflammation. We investigate changes in the plasma membrane’s proximity to the critical point as a response to stimulation by various pro- and anti-inflammatory agents. Pro-inflammatory (interferon γ , Kdo 2-Lipid A, lipopolysaccharide) perturbations induce an increase in the transition temperature of giant plasma membrane vesicles; anti-inflammatory interleukin 4 has the opposite effect. These changes recapitulate complex plasma membrane composition changes, and are consistent with lipid criticality playing a master regulatory role: being closer to critical conditions increases membrane protein activity.

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Monoclonal antibodies as probes of epithelial membrane polarization.

The Journal of Cell Biology ◽

10.1083/jcb.101.6.2173 ◽

1985 ◽

Vol 101 (6) ◽

pp. 2173-2180 ◽

Cited By ~ 15

Author(s):

R J Turner ◽

J Thompson ◽

S Sariban-Sohraby ◽

J S Handler

Keyword(s):

Monoclonal Antibodies ◽

Plasma Membrane ◽

Membrane Lipids ◽

Apical Plasma Membrane ◽

Epithelial Cell Line ◽

Lipid Species ◽

Antigen Complex ◽

Kidney Epithelial Cell ◽

Kidney Epithelial Cell Line ◽

Lipid Antigen

Monoclonal antibodies directed against antigens in the apical plasma membrane of the toad kidney epithelial cell line A6 were produced to probe the phenomena that underlie the genesis and maintenance of epithelial polarity. Two of these antibodies, 17D7 and 18C3, were selected for detailed study here. 17D7 is directed against a 23-kD peptide found on both the apical and basolateral surfaces of the A6 epithelium whereas 18C3 recognizes a lipid localized to the apical membrane only. This novel observation of an apically localized epithelial lipid species indicates the existence of a specific sorting and insertion process for this, and perhaps other, epithelial plasma membrane lipids. The antibody-antigen complexes formed by both these monoclonal antibodies are rapidly internalized by the A6 cells, but only the 18C3-antigen complex is recycled to the plasma membrane. In contrast to the apical localization of the free antigen, however, the 18C3-antigen complex is recycled to both the apical and basolateral surface of the epithelium, which indicates that monoclonal antibody binding interferes in some way with the normal sorting process for this apical lipid antigen.

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Regulation of the electrogenic H+ channel in the plasma membrane of neutrophils: possible role of phospholipase A2, internal and external protons

Biochemical Journal ◽

10.1042/bj2920445 ◽

1993 ◽

Vol 292 (2) ◽

pp. 445-450 ◽

Cited By ~ 20

Author(s):

A Kapus ◽

K Suszták ◽

E Ligeti

Keyword(s):

Plasma Membrane ◽

Phospholipase A2 ◽

Neutrophil Granulocytes ◽

Dependent Manner ◽

Concentration Dependent Manner ◽

Conducting Pathway ◽

External Ph ◽

Force Relationship ◽

Stimulation Of

Possible factors regulating the opening of and the rate of H+ flux through a recently described, Cd(2+)-sensitive, phorbol ester- and arachidonic acid (AA)-activatable H(+)-conducting pathway in the plasma membrane of neutrophil granulocytes were investigated. (1) The phospholipase A2 blocker p-bromophenacyl bromide (BPB) inhibited the phorbol 12-myristate 13-acetate (PMA)-induced activation of this channel in a concentration-dependent manner (IC50, 4 microM). (2) Neither BPB nor the protein kinase C (PKC) inhibitor staurosporine influenced the AA-elicited stimulation of this route. (3) Intracellular acidification (cytoplasmic pH below 6.9) itself is capable of activating an electrogenic, Cd(2+)-sensitive H+ efflux indicating that protons can open up this route in the absence of any other stimulator. (4) PMA significantly decreases the intracellular H+ concentration ([H+]i) threshold for the opening of the channel, thus providing a conductive state at resting pH values, and elevates the rate of H+ efflux at any [H+]i. (5) Changes in external pH also modify the operation of the channel: above an extracellular pH (pH(o)) value of 7.4, the H(+)-flux/driving force relationship is approx. 5-fold greater than below this value. Our results suggest a multifactorial regulation of the electrogenic H+ channel: most probably PKC activates the channel indirectly, via stimulation of phospholipase A2 that subsequently liberates AA. In addition to this, the channel conductance seems to be promoted by internal H+ and inhibited by external H+.

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Epidermal Growth Factor Receptor Activation Remodels the Plasma Membrane Lipid Environment To Induce Nanocluster Formation

Molecular and Cellular Biology ◽

10.1128/mcb.01615-09 ◽

2010 ◽

Vol 30 (15) ◽

pp. 3795-3804 ◽

Cited By ~ 71

Author(s):

Nicholas Ariotti ◽

Hong Liang ◽

Yufei Xu ◽

Yueqiang Zhang ◽

Yoshiya Yonekubo ◽

...

Keyword(s):

Plasma Membrane ◽

Growth Factor ◽

Epidermal Growth Factor ◽

Molecular Mechanisms ◽

Receptor Activation ◽

Membrane Lipid ◽

Dependent Manner ◽

Epidermal Growth ◽

Lipid Environment ◽

Lateral Segregation

ABSTRACT Signal transduction is regulated by the lateral segregation of proteins into nanodomains on the plasma membrane. However, the molecular mechanisms that regulate the lateral segregation of cell surface receptors, such as receptor tyrosine kinases, upon ligand binding are unresolved. Here we used high-resolution spatial mapping to investigate the plasma membrane nanoscale organization of the epidermal growth factor (EGF) receptor (EGFR). Our data demonstrate that in serum-starved cells, the EGFR exists in preformed, cholesterol-dependent, actin-independent nanoclusters. Following stimulation with EGF, the number and size of EGFR nanoclusters increase in a time-dependent manner. Our data show that the formation of EGFR nanoclusters requires receptor tyrosine kinase activity. Critically, we show for the first time that production of phosphatidic acid by phospholipase D2 (PLD2) is essential for ligand-induced EGFR nanocluster formation. In accordance with its crucial role in regulating EGFR nanocluster formation, we demonstrate that modulating PLD2 activity tunes the degree of EGFR nanocluster formation and mitogen-activated protein kinase signal output. Together, these data show that EGFR activation drives the formation of signaling domains by regulating the production of critical second-messenger lipids and modifying the local membrane lipid environment.

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