02581nas a2200277 4500008004100000022001400041245012800055210006900183260008100252300002000333490000700353520154700360653001501907653001601922653002901938653001401967100002201981700002102003700002402024700002902048700002302077700002902100700002502129700002302154856012602177 2014 eng d a1476-459800aCholesterol depletion by methyl-beta-cyclodextrin augments tamoxifen induced cell death by enhancing its uptake in melanoma0 aCholesterol depletion by methylbetacyclodextrin augments tamoxif a236 GRAYS INN RD, FLOOR 6, LONDON WC1X 8HL, ENGLANDbBIOMED CENTRAL LTDcSEP aArticle No. 2040 v133 a

Background: Despite modern advances in treatment, skin cancer is still one of the most common causes of death in the western countries. Chemotherapy plays an important role in melanoma management. Tamoxifen has been used either alone or in-combination with other chemotherapeutic agents to treat melanoma. However, response rate of tamoxifen as a single agent has been comparatively low. In the present study, we investigated whether treatment with methyl-beta-cyclodextrin (MCD), a cholesterol depleting agent, increases the efficacy of tamoxifen in melanoma cells. Methods: This was a two-part study that incorporated in vitro effects of tamoxifen and MCD combination by analyzing cell survival, apoptosis and cell cycle analysis and in vivo antitumor efficacy on tumor isografts in C57BL/6J mice. Results: MCD potentiated tamoxifen induced anticancer effects by causing cell cycle arrest and induction of apoptosis. Sensitization to tamoxifen was associated with down regulation of antiapoptotic protein Bcl-2, up-regulation of proapoptotic protein Bax, reduced caveolin-1 (Cav-1) and decreased pAkt/pERK levels. Co-administration of tamoxifen and MCD caused significant reduction in tumor volume and tumor weight in mice due to enhancement of drug uptake in the tumor. Supplementation with cholesterol abrogated combined effect of tamoxifen and MCD. Conclusion: Our results emphasize a potential synergistic effect of tamoxifen with MCD, and therefore, may provide a unique therapeutic window for improvement in melanoma treatment.

10aCaveolin-110aCholesterol10aMethyl beta-cyclodextrin10aTamoxifen1 aMohammad, Naoshad1 aMalvi, Parmanand1 aMeena, Avtar, Singh1 aSingh, Shivendra, Vikram1 aChaube, Balkrishna1 aVannuruswamy, Garikapati1 aKulkarni, Mahesh, J.1 aBhat, Manoj, Kumar uhttps://library.ncl.res.in/content/cholesterol-depletion-methyl-beta-cyclodextrin-augments-tamoxifen-induced-cell-death-002251nas a2200253 4500008004100000022001400041245006200055210006100117260000800178300001100186490000800197520145900205653002701664653001601691653002601707653003201733653001601765653003601781100002101817700002001838700002801858700002001886856009101906 2020 eng d a0009-308400aRole of cholesterol-mediated effects in GPCR heterodimers0 aRole of cholesterolmediated effects in GPCR heterodimers cMAR a1048520 v2273 a

G protein-coupled receptors (GPCRs) are transmembrane receptors that mediate a large number of cellular responses. The organization of GPCRs into dimers and higher-order oligomers is known to allow a larger repertoire of downstream signaling events. In this context, a crosstalk between the adenosine and dopamine receptors has been reported, indicating the presence of heterodimers that are functionally relevant. In this paper, we explored the effect of membrane cholesterol on the adenosine(2A) (A(2A)) and dopamine D-3 (D-3) receptors using coarse-grain molecular dynamics simulations. We analyzed cholesterol interaction sites on the A(2A) receptor and were able to reproduce the sites indicated by crystallography and previous atomistic simulations. We predict novel cholesterol interaction sites on the D-3 receptor that could be important in the reported cholesterol sensitivity in receptor function. Further, we analyzed the formation of heterodimers between the two receptors. Our results suggest that membrane cholesterol modulates the relative population of several co-existing heterodimer conformations. Both direct receptor-cholesterol interaction and indirect membrane effects contribute toward the modulation of heterodimer conformations. These results constitute one of the first examples of modulation of GPCR hetero-dimerization by membrane cholesterol, and could prove to be useful in designing better therapeutic strategies.

10aAdenosine(2A) receptor10aCholesterol10aDopamine D-3 receptor10aG protein-coupled receptors10aHeterodimer10aMARTINI coarse-grain simulation1 aPrasanna, Xavier1 aMohole, Madhura1 aChattopadhyay, Amitabha1 aSengupta, Durba uhttps://library.ncl.res.in/content/role-cholesterol-mediated-effects-gpcr-heterodimers02238nas a2200217 4500008004100000022001400041245008900055210006900144260000800213520145500221653002401676653002501700653001601725653001401741653002901755100002501784700003401809700002701843700003601870856011401906 2020 eng d a0272-434000aRole of microglia in regulating cholesterol and tau pathology in alzheimer's disease0 aRole of microglia in regulating cholesterol and tau pathology in cMAY3 a

Cholesterol, a principal constituent of the cell membrane, plays a crucial role in the brain by regulating the synaptic transmission, neuronal signaling, as well as neurodegenerative diseases. Defects in the cholesterol trafficking are associated with enhanced generation of hyperphosphorylated Tau and Amyloid-beta protein. Tau, a major microtubule-associated protein in the brain, is the key regulator of the mature neuron. Abnormally hyperphosphorylated Tau hampers the major functions related to microtubule assembly by promoting neurofibrillary tangles of paired helical filaments, twisted ribbons, and straight filaments. The observed pathological changes due to impaired cholesterol and Tau protein accumulation cause Alzheimer's disease. Thus, in order to regulate the pathogenesis of Alzheimer's disease, regulation of cholesterol metabolism, as well as Tau phosphorylation, is essential. The current review provides an overview of (1) cholesterol synthesis in the brain, neurons, astrocytes, and microglia; (2) the mechanism involved in modulating cholesterol concentration between the astrocytes and brain; (3) major mechanisms involved in the hyperphosphorylation of Tau and amyloid-beta protein; and (4) microglial involvement in its regulation. Thus, the answering key questions will provide an in-depth information on microglia involvement in managing the pathogenesis of cholesterol-modulated hyperphosphorylated Tau protein.

10aAlzheimer's disease10aAmyloid-beta protein10aCholesterol10amicroglia10aTau hyperphosphorylation1 aNanjundaiah, Shwetha1 aChidambaram, Hariharakrishnan1 aChandrashekar, Madhura1 aChinnathambi, Subashchandrabose uhttps://library.ncl.res.in/content/role-microglia-regulating-cholesterol-and-tau-pathology-alzheimers-disease02054nas a2200205 4500008004100000022001400041245009000055210006900145260000800214520132800222653001601550653003301566653001501599653002401614653003701638653001701675100002401692700002001716856011201736 2021 eng d a0022-263100aRole of cholesterol in transmembrane dimerization of the ErbB2 growth factor receptor0 aRole of cholesterol in transmembrane dimerization of the ErbB2 g cJAN3 a

The association of ErbB2 growth factor receptors is critical for cell growth and potentiates tumor proliferation in several cancer types. An important aspect in ErbB2 association is the role of lipids such as cholesterol, especially since their metabolism is often reprogrammed in cancer cells. Here, we have coupled metadynamics with coarse-grain simulations to identify cholesterol effects in the transmembrane dimerization of ErbB2 receptors. Overall, cholesterol interactions are observed with the receptor that directly tunes the association energetics. Several dimer conformations are identified both in the presence and absence of cholesterol, although the dimer regime appears to be more favorable in the presence of cholesterol. We observe an overall modulation of the underlying energy profile and the symmetric active and inactive conformational states are not distinguished in the presence of cholesterol. We show that cholesterol binds to the receptor transmembrane domain at a site (CRAC motif) that overlaps with the dimer interface (SmXXXSm motif). The competition between the transmembrane interactions and cholesterol interactions decides the final conformational landscape. Our work is an important step toward characterizing cholesterol effects in ErbB2 membrane receptor function. [GRAPHICS] .

10aCholesterol10aErbB2 growth factor receptor10aHer2 dimer10aJuxtamembrane dimer10aMartini coarse-grain simulations10aMetadynamics1 aPawar, Aiswarya, B.1 aSengupta, Durba uhttps://library.ncl.res.in/content/role-cholesterol-transmembrane-dimerization-erbb2-growth-factor-receptor02437nas a2200253 4500008004100000022001400041245012000055210006900175260000800244490000700252520159800259653001601857653002401873653001401897653001601911653000901927100001701936700002101953700001901974700002301993700001802016700001902034856013002053 2023 eng d a8756-793800aAmino acid abundance and composition in cell culture medium affects trace metal tolerance and cholesterol synthesis0 aAmino acid abundance and composition in cell culture medium affe cJAN0 v393 a

Amino acid compositions of cell culture media are empirically designed to enhance cell growth and productivity and vary both across media formulations and over the course of culture due to imbalance in supply and consumption. The interconnected nature of the amino acid transporters and metabolism suggests that changes in amino acid composition can affect cell physiology. In this study, we explore the effect of a step change in amino acid composition from a DMEM: F12-based medium to a formulation varying in relative abundances of all amino acids, evaluated at two amino acid concentrations (lean LAA vs. rich HAA). Cell growth was inhibited in LAA but not HAA. In addition to the expected effects on expression of the cell cycle, amino acid response and mTOR pathway genes in LAA, we observed an unanticipated effect on zinc uptake and efflux genes. This was accompanied by a lower tolerance to zinc supplementation in LAA but not in the other formulations. Histidine was sufficient but not necessary to prevent such zinc toxicity. Additionally, an unanticipated downregulation of genes in the cholesterol synthesis pathway was observed in HAA, accompanied by an increase in cellular cholesterol content, which may depend on the relative abundances of glutamine and other amino acids. This study shows that changes in the amino acid composition without any evident effect on growth may have profound effects on metabolism. Such analyses can help rationalize the designing of medium and feed formulations for bioprocess applications beyond replenishment of consumed components.

10aAmino acids10acell culture medium10aCHO cells10aCholesterol10azinc1 aRawat, Jyoti1 aBhambri, Aksheev1 aPandey, Ujjiti1 aBanerjee, Sanchita1 aPillai, Beena1 aGadgil, Mugdha uhttps://library.ncl.res.in/content/amino-acid-abundance-and-composition-cell-culture-medium-affects-trace-metal-tolerance-and02774nas a2200241 4500008004100000022001400041245015600055210006900211260000800280300001400288490000700302520190400309653001902213653001602232653000902248653003602257653001502293653002702308100002502335700002002360700002802380856012402408 2026 eng d a1948-719300aSpecificity and promiscuity of phosphoinositide lipid interactions with the serotonin1A receptor: insights from submillisecond coarse-grain simulations0 aSpecificity and promiscuity of phosphoinositide lipid interactio cMAR a1104-11140 v173 a

G protein-coupled receptors (GPCRs) are lipid-dependent membrane receptors that serve as important cell signaling hubs. Phosphoinositide (PIP) lipids represent an important class of anionic lipids that play vital roles in neuronal function and signaling. PIP lipids have been reported to modulate GPCR function, although the specificity and molecular details of the interactions are still not clear. An important GPCR in this context is the serotonin(1A) receptor, a neurotransmitter GPCR, which has been reported to interact with phosphatidylinositol 4-phosphate (PIP1) lipids. In this work, we computationally analyzed the specificity of the serotonin(1A) receptor-PIP lipid interactions using coarse-grain molecular dynamics simulations. Our results predict that four anionic lipid sites are present at the receptor surface, although the relative populations are dependent on the lipid type. PIP1 lipids exhibit the highest interaction at a charged cleft formed by transmembrane helices VI and VII. We observed electrostatic interactions at a cluster of charged residues (Arg341, Lys342, Lys345) and hydrophobic and aromatic interactions at residue Ile349 and Tyr402. In contrast, phosphatidylinositol 4,5-bisphosphate (PIP2) and phosphatidylinositol 3,4,5-trisphosphate (PIP3) lipids interact more with transmembrane helix IV. We observed that anionic phospholipids such as phosphatidylserine (PS) interact at these sites, although their occupancy at these sites is much reduced. By elucidating the molecular determinants of these interactions in silico, this study generates novel, testable hypotheses regarding the functional role of specific lipid-receptor contacts. Our work constitutes an important step in analyzing molecular signatures of phosphoinositide lipid-GPCR interactions in the overall context of diverse roles of phosphoinositides in neuronal function and signaling.

10aanionic lipids10aCholesterol10aGPCR10aMARTINIcoarse-grain simulations10aPIP lipids10aserotonin(1A) receptor1 aNikte, Siddhanta, V.1 aSengupta, Durba1 aChattopadhyay, Amitabha uhttps://library.ncl.res.in/content/specificity-and-promiscuity-phosphoinositide-lipid-interactions-serotonin1a-receptor