Nanotubes connecting B lymphocytes: High impact of differentiation-dependent lipid composition on their growth and mechanics

Nanotubes (NTs) are thin, long membranous structures forming novel, yet poorly known communication pathways between various cell types. Key mechanisms controlling their growth still remained poorly understood. Since NT-forming capacity of immature and mature B cells was found largely different, we investigated how lipid composition and molecular order of the membrane affect NT-formation. Screening B cell lines with various differentiation stages revealed that NT-growth linearly correlates with membrane ganglioside levels, while it shows maximum as a function of cholesterol level. NT-growth of B lymphocytes is promoted by raftophilic phosphatidylcholine and sphingomyelin species, various glycosphingolipids, and docosahexaenoic acid-containing inner leaflet lipids, through supporting membrane curvature, as demonstrated by comparative lipidomic analysis of mature versus immature B cell membranes. Targeted modification of membrane cholesterol and sphingolipid levels altered NT-forming capacity confirming these findings, and also highlighted that the actual lipid raft number may control NT-growth via defining the number of membrane-F-actin coupling sites. Atomic force microscopic mechano-manipulation experiments further proved that mechanical properties (elasticity or bending stiffness) of B cell NTs also depend on the actual membrane lipid composition. Data presented here highlight importance of the lipid side in controlling intercellular, nanotubular, regulatory communications in the immune system

Effect of Inflammation on Female Gonadotropin-Releasing Hormone (GnRH) Neurons: Mechanisms and Consequences

Inflammation has a well-known suppressive effect on fertility. The function of gonadotropin-releasing hormone (GnRH) neurons, the central regulator of fertility is substantially altered during inflammation in females. In our review we discuss the latest results on how the function of GnRH neurons is modified by inflammation in females. We first address the various effects of inflammation on GnRH neurons and their functional consequences. Second, we survey the possible mechanisms underlying the inflammation-induced actions on GnRH neurons. The role of several factors will be discerned in transmitting inflammatory signals to the GnRH neurons: cytokines, kisspeptin, RFamide-related peptides, estradiol and the anti-inflammatory cholinergic pathway. Since aging and obesity are both characterized by reproductive decline our review also focuses on the mechanisms and pathophysiological consequences of the impact of inflammation on GnRH neurons in aging and obesity

Estradiol-Induced Epigenetically Mediated Mechanisms and Regulation of Gene Expression

Gonadal hormone 17β-estradiol (E2) and its receptors are key regulators of gene transcription by binding to estrogen responsive elements in the genome. Besides the classical genomic action, E2 regulates gene transcription via the modification of epigenetic marks on DNA and histone proteins. Depending on the reaction partner, liganded estrogen receptor (ER) promotes DNA methylation at the promoter or enhancer regions. In addition, ERs are important regulators of passive and active DNA demethylation. Furthermore, ERs cooperating with different histone modifying enzymes and chromatin remodeling complexes alter gene transcription. In this review, we survey the basic mechanisms and interactions between estrogen receptors and DNA methylation, demethylation and histone modification processes as well as chromatin remodeling complexes. The particular relevance of these mechanisms to physiological processes in memory formation, embryonic development, spermatogenesis and aging as well as in pathophysiological changes in carcinogenesis is also discussed

The p53 and Calcium Regulated Actin Rearrangement in Model Cells

Long-term cellular stress maintains high intracellular Ca2+ concentrations which ultimately initiates apoptosis. Our interest is focused on how the gelsolin (GSN) and junctional mediating and regulating Y protein (JMY) play important roles in stress response. Both of these proteins can bind p53 and actin. We investigated using in vitro fluorescence spectroscopy and found that the p53 competes with actin in GSN to inhibit p53–JMY complex formation. A high Ca2+ level initializes p53 dimerization; the dimer competes with actin on JMY, which can lead to p53–JMY cotransport into the nucleus. Here we investigated how the motility and division rate of HeLa cells changes due to low-voltage electroporation of GSN or JMY in scratching assays. We revealed that JMY inhibits their motion, but that it can accelerate the cell division. GSN treatment slows down cell division but does not affect cell motility. HeLa cells fully recovered the gap 20 h after the electroporation with JMY and then started to release from the glass slides. Taken together, our in vitro results indicate that GSN and JMY may play an important role in the cellular stress response

Table1_Cyclodextrin derivatives decrease Transient Receptor Potential vanilloid 1 and Ankyrin 1 ion channel activation via altering the surrounding membrane microenvironment by cholesterol depletion.DOCX

Transient Receptor Potential Vanilloid 1 (TRPV1) and Ankyrin 1 (TRPA1) are nonselective cation channels expressed in primary sensory neurons and several other non-neuronal structures such as immune cells, keratinocytes, and vascular smooth muscle cells. They play important roles in nociception, pain processing and their chanellopathies are associated with the development of several pathological conditions. They are located in cholesterol- and sphingolipid-rich membrane lipid raft regions serving as platforms to modulate their activations. We demonstrated earlier that disruption of these lipid rafts leads to decreased TRP channel activation and exerts analgesic effects. Cyclodextrins are macrocyclic molecules able to form host-guest complexes with cholesterol and deplete it from the membrane lipid rafts. The aim of this study was to investigate 8 structurally different (methylated and non-methylated) CD derivatives on cell viability, mitochondrial membrane potential, membrane composition and activation abilities of the TRPV1 and TRPA1 channels. We showed that non-methylated derivatives have preferable safety profiles compared to methylated ones. Furthermore, methylated derivatives reduced mitochondrial membrane potential. However, all investigated derivatives influence the ordered cell membrane structure depleting membrane cholesterol and inhibit the TRPV1 agonist capsaicin- and the TRPA1 agonist allyl isothiocyanate-induced Ca2+−influx. This mechanism of action might provide novel perspectives for the development of peripherally acting analgesics via indirectly decreasing the generation and transmission of nociceptive signals.</p

Cyclodextrin derivatives decrease Transient Receptor Potential vanilloid 1 and Ankyrin 1 ion channel activation via altering the surrounding membrane microenvironment by cholesterol depletion

Transient Receptor Potential Vanilloid 1 (TRPV1) and Ankyrin 1 (TRPA1) are nonselective cation channels expressed in primary sensory neurons and several other non-neuronal structures such as immune cells, keratinocytes, and vascular smooth muscle cells. They play important roles in nociception, pain processing and their chanellopathies are associated with the development of several pathological conditions. They are located in cholesterol- and sphingolipid-rich membrane lipid raft regions serving as platforms to modulate their activations. We demonstrated earlier that disruption of these lipid rafts leads to decreased TRP channel activation and exerts analgesic effects. Cyclodextrins are macrocyclic molecules able to form host-guest complexes with cholesterol and deplete it from the membrane lipid rafts. The aim of this study was to investigate 8 structurally different (methylated and non-methylated) CD derivatives on cell viability, mitochondrial membrane potential, membrane composition and activation abilities of the TRPV1 and TRPA1 channels. We showed that non-methylated derivatives have preferable safety profiles compared to methylated ones. Furthermore, methylated derivatives reduced mitochondrial membrane potential. However, all investigated derivatives influence the ordered cell membrane structure depleting membrane cholesterol and inhibit the TRPV1 agonist capsaicin- and the TRPA1 agonist allyl isothiocyanate-induced Ca2+−influx. This mechanism of action might provide novel perspectives for the development of peripherally acting analgesics via indirectly decreasing the generation and transmission of nociceptive signals