Exploring the Organization and Dynamics of Hippocampal Membranes Utilizing Pyrene Fluorescence

Saxena, Roopali; Shrivastava, Sandeep; Chattopadhyay, Amitabha

doi:10.1021/jp804353m

Cited by 32 publications

(37 citation statements)

References 40 publications

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“…1), although there was a leveling off at higher concentrations of MβCD. The red shift in emission maximum is possibly due to an increase in apparent polarity experienced by the fluorophore, possibly because of increase in water penetration in the membrane induced by cholesterol depletion, as previously reported using polarity-sensitive vibronic peak ratio of pyrene [49]. The magnitudes of REES displayed by hippocampal membranes with varying cholesterol content are shown in Figs.…”

Section: Resultssupporting

confidence: 72%

Cholesterol-induced changes in hippocampal membranes utilizing a phase-sensitive fluorescence probe

Saxena

Shrivastava

Chattopadhyay

2015

Biochimica et Biophysica Acta (BBA) - Biomembranes

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The function of membrane receptors in the nervous system depends on physicochemical characteristics of neuronal membranes such as membrane order and phase. In this work, we have monitored the changes in hippocampal membrane order and related parameters by cholesterol and protein content utilizing a Nile Red-based phase-sensitive fluorescent membrane probe NR12S. Since alteration of membrane cholesterol is often associated with membrane phase change, the phase-sensitive nature of NR12S fluorescence becomes useful in these experiments. Our results show that fluorescence spectroscopic parameters such as emission maximum, anisotropy, and lifetime of NR12S display characteristic dependence on membrane cholesterol content. Interestingly, cholesterol-dependent red edge excitation shift is displayed by NR12S under these conditions. Hippocampal membranes exhibited reduction in liquid-ordered phase upon cholesterol depletion. These results provide insight into changes in hippocampal membrane order in the overall context of cholesterol and protein modulation.

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Section: Resultssupporting

confidence: 72%

Cholesterol-induced changes in hippocampal membranes utilizing a phase-sensitive fluorescence probe

Saxena

Shrivastava

Chattopadhyay

2015

Biochimica et Biophysica Acta (BBA) - Biomembranes

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Section: Introductionmentioning

confidence: 93%

“…In this overall context, we have demonstrated the requirement of membrane cholesterol in modulating the function of the serotonin1A receptor Chattopadhyay, 2004, 2006;Paila et al, 2008;Paila and Chattopadhyay, 2010;Shrivastava et al, 2010;Jafurulla and Chattopadhyay, 2013). A continuing effort in our laboratory has been to explore how to correlate these cholesterol-dependent functional changes of the serotonin1A receptor with alterations in membrane organization and dynamics (Mukherjee et al, 2007;Saxena et al, 2008;Singh et al, 2012).In this work, we have monitored the change in viscosity associated with cholesterol depletion in hippocampal membranes using viscosity-dependent fluorescence depolarization A major application of molecular rotors is to measure microviscosity in biological systems since the intramolecular rotation depends on viscosity of the immediate environment in which the molecular rotor is localized Theodorakis, 2007, 2010;Kuimova et al, 2008;Levitt et al, 2009;Wu et al, 2013). Our results using BODIPY-C12 show that the viscosity of hippocampal membranes exhibits reduction under conditions of cholesterol depletion.…”

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confidence: 94%

Molecular rheology of neuronal membranes explored using a molecular rotor: Implications for receptor function

Pal

Chakraborty

Bandari

et al. 2016

Chemistry and Physics of Lipids

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The role of membrane cholesterol as a crucial regulator in the structure and function of membrane proteins and receptors is well documented. However, there is a lack of consensus on the mechanism for such regulation. We have previously shown that the function of an important neuronal receptor, the serotonin1A receptor, is modulated by cholesterol in hippocampal membranes. With an overall objective of addressing the role of 3 membrane physical properties in receptor function, we measured the viscosity of hippocampal membranes of varying cholesterol content using a meso-substituted fluorophore (BODIPY-C12) based on the BODIPY probe. BODIPY-C12 acts as a fluorescent molecular rotor and allows measurement of hippocampal membrane viscosity through its characteristic viscosity-sensitive fluorescence depolarization. A striking feature of our results is that specific agonist binding by the serotonin1A receptor exhibits close correlation with hippocampal membrane viscosity, implying the importance of global membrane properties in receptor function. We envision that our results are important in understanding GPCR regulation by the membrane environment, and is relevant in the context of diseases in which GPCR signaling plays a major role and are characterized by altered membrane fluidity.Abbreviations: 2-AS, 2-(9-anthroyloxy)stearic acid; 12-AS, 12-(9-anthroyloxy)stearic acid; BODIPY, 4,4-difluoro-4-bora-3a,4a-diaza-s-indacene; GPCR, G protein-coupled receptor; 8-12-PC, 1-palmitoyl-2-(12-doxyl)stearoyl-sn-glycero-3-phosphocholine; DMPC, 1,2-dimyristoyl-sn-glycero-3-phosphocholine; DOPC, 1,2-dioleoylsn-glycero-3-phosphocholine; MβCD, methyl-β-cyclodextrin; Tempo-PC, 1,2-dioleoyl-snglycero-3-phosphotempocholine Keywords: Molecular rotor; hippocampal membrane; viscosity; cholesterol; neuronal receptor IntroductionBiological membranes are complex, highly organized, two-dimensional, supramolecular assemblies of a diverse variety of lipids and proteins. The function of membranes is to allow cellular compartmentalization, and impart an identity to individual cells and organelles, besides providing an appropriate environment for proper functioning of membrane proteins. Interestingly, cellular membranes in the nervous system are characterized by very high concentration and remarkable diversity of lipids, and these are correlated with increased complexity in the function of the nervous system (Sastry, 1985;Wenk, 2005). In this context, cholesterol represents an important lipid since brain cholesterol has been implicated in a number of neurological disorders (Chattopadhyay and Paila, 2007;Martín et al., 2014), some of which share a common etiology of defective cholesterol 4 metabolism in the brain (Porter and Herman, 2011). More importantly, the function of neuronal receptors depends on cholesterol (Pucadyil and Chattopadhyay, 2006;Allen et al., 2007;Paila and Chattopadhyay, 2010;Jafurulla and Chattopadhyay, 2013), which affects neurotransmission, resulting in mood and anxiety disorders (Papakostas et al., 2004). In spite of ...

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“…[26][27][28][29]47 We have previously shown, using pyrene vibronic band intensity ratio, that the apparent polarity of hippocampal membranes exhibits an increase upon cholesterol depletion. 29 Table S2). …”

Section: ■ Results and Discussionmentioning

confidence: 99%

Organization and Dynamics of Hippocampal Membranes in a Depth-Dependent Manner: An Electron Spin Resonance Study

Singh

Tarafdar²,

Swamy³

et al. 2012

J. Phys. Chem. B

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Organization and dynamics of neuronal membranes represent crucial determinants for the function of neuronal receptors and signal transduction. Previous work from our laboratory has established hippocampal membranes as a convenient natural source for studying neuronal receptors. In this work, we have monitored the organization and dynamics of hippocampal membranes and their modulation by cholesterol and protein content utilizing location (depth)-specific spin-labeled phospholipids by ESR spectroscopy. The choice of ESR spectroscopy is appropriate due to slow diffusion encountered in crowded environments of neuronal membranes. Analysis of ESR spectra shows that cholesterol increases hippocampal membrane order while membrane proteins increase lipid dynamics resulting in disordered membranes. These results are relevant in understanding the complex organization and dynamics of hippocampal membranes. Our results are significant in the overall context of membrane organization under low cholesterol conditions and could have implications in neuronal diseases characterized by low cholesterol conditions due to defective cholesterol metabolism. ■ INTRODUCTIONBiological membranes are complex noncovalent assemblies of a diverse variety of lipids and proteins that allow cellular compartmentalization, thereby imparting an identity to the cell. The lipid composition of cells that makes up the nervous system is unique and has been correlated with increased complexity in the organization of the nervous system during evolution.1 The nervous system characteristically contains a very high concentration of lipids and displays remarkable lipid diversity.2 Cholesterol is an important lipid in this context since it is known to regulate the function of neuronal receptors, 3−5 thereby affecting neurotransmission and giving rise to mood and anxiety disorders. 6 Cholesterol is often found distributed nonrandomly in domains in biological and model membranes.7−9 Many of these domains (sometimes termed as 'lipid rafts' 10 ) are thought to be important for the maintenance of membrane structure and function, although characterizing the spatiotemporal resolution of these domains has proven to be challenging. 11−13 A unique property of cholesterol that contributes to its capacity to form membrane domains is its ability to form a liquid-ordered-like phase in higher eukaryotic plasma membranes.14 The idea of such specialized membrane domains assumes significance in cell biology since physiologically important functions such as membrane sorting and trafficking, signal transduction processes, and the entry of pathogens have been attributed to these domains. 15,16 Interestingly, a number of neurological diseases share a common etiology of defective cholesterol metabolism in the brain, 17 yet the organization and dynamics of neuronal membranes as a consequence of alterations in membrane cholesterol is poorly understood. 18−20Previous work from our laboratory has established native hippocampal membranes as a convenient natural source for expl...

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Exploring the Organization and Dynamics of Hippocampal Membranes Utilizing Pyrene Fluorescence

Cited by 32 publications

References 40 publications

Cholesterol-induced changes in hippocampal membranes utilizing a phase-sensitive fluorescence probe

Cholesterol-induced changes in hippocampal membranes utilizing a phase-sensitive fluorescence probe

Molecular rheology of neuronal membranes explored using a molecular rotor: Implications for receptor function

Organization and Dynamics of Hippocampal Membranes in a Depth-Dependent Manner: An Electron Spin Resonance Study

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