Cell lipid droplet heterogeneity and altered biophysical properties induced by cell stress and metabolic imbalance.

Lipid droplets (LD) are important regulators of lipid metabolism and are implicated in several diseases. However, the mechanisms underlying the roles of LD in cell pathophysiology remain elusive. Hence, new approaches that enable better characterization of LD are essential.

Laurdan in live cell imaging: Effect of acquisition settings, cell culture conditions and data analysis on generalized polarization measurements.

Cell function is highly dependent on membrane structure, organization, and fluidity. Therefore, methods to probe the biophysical properties of biological membranes are required. Determination of generalized polarization (GP) values using Laurdan in fluorescence microscopy studies is one of the most widely-used methods to investigate changes in membrane fluidity in vitro and in vivo.

Biophysical impact of sphingosine and other abnormal lipid accumulation in Niemann-Pick disease type C cell models.

Niemann-Pick disease type C (NPC) is a complex and rare pathology, which is mainly associated to mutations in the NPC1 gene. This disease is phenotypically characterized by the abnormal accumulation of multiple lipid species in the acidic compartments of the cell. Due to the complexity of stored material, a clear molecular mechanism explaining NPC pathophysiology is still not established.

Biophysical Analysis of Lipid Domains by Fluorescence Microscopy.

The study of the structure and dynamics of membrane domains in vivo is a challenging task. However, major advances could be achieved through the application of microscopic and spectroscopic techniques coupled with the use of model membranes, where the relations between lipid composition and the type, amount and properties of the domains present can be quantitatively studied.This chapter provides protocols to study membrane organization and visualize membrane domains by fluorescence microscopy both in artificial membrane and living cell models of Gaucher Disease (GD ).

Canonical and 1-Deoxy(methyl) Sphingoid Bases: Tackling the Effect of the Lipid Structure on Membrane Biophysical Properties.

Compared to the canonical sphingoid backbone of sphingolipids (SLs), atypical long-chain bases (LCBs) lack C1-OH (1-deoxy-LCBs) or C1-CHOH (1-deoxymethyl-LCBs). In addition, when unsaturated, they present a -double bond instead of the canonical  Δ4-5 -double bond. These atypical LCBs are directly correlated with the development and progression of hereditary sensory and autonomic neuropathy type 1 and diabetes type II through yet unknown mechanisms.

Ceramide Domains in Health and Disease: A Biophysical Perspective.

Ceramides are the central molecules in sphingolipid metabolism. In addition, they are recognized as important modulators of cell function, playing key roles in several cellular processes that range from cell proliferation to cell death. Moreover, ceramides were implicated in multiple diseases, including cancer, neurodegenerative and metabolic diseases, and also in infection by different pathogens.

The role of ceramide in regulating endoplasmic reticulum function.

Sphingolipids (SLs) are an important class of membrane lipids containing a long chain sphingoid base backbone. SL synthesis is compartmentalized between two major cell organelles, the endoplasmic reticulum (ER) and the Golgi apparatus. The initial steps of sphingolipid synthesis take place in the ER, where the simplest SL, ceramide, is synthesized.

N,O-Iminoboronates: Reversible Iminoboronates with Improved Stability for Cancer Cells Targeted Delivery.

Herein a new class of iminoboronates obtained from 2-acetylbenzene boronic acids and aminophenols is presented. The N,O-ligand topology enabled the formation of an additional B-O bond that locks the boron center in a tetrahedral geometry. This molecular arrangement decisively contributes to improve the construct's stability in biocompatible conditions and retaining the iminoboronate reversibility in more acidic environments.

Modular Assembly of Reversible Multivalent Cancer-Cell-Targeting Drug Conjugates.

Herein is described a new modular platform for the construction of cancer-cell-targeting drug conjugates. Tripodal boronate complexes featuring reversible covalent bonds were designed to accommodate a cytotoxic drug (bortezomib), poly(ethylene glycol) (Peg) chains, and folate targeting units. The B-complex core was assembled in one step, proved stable under biocompatible conditions, namely, in human plasma (half-life up to 60 h), and underwent disassembly in the presence of glutathione (GSH).

Pathological levels of glucosylceramide change the biophysical properties of artificial and cell membranes.

Glucosylceramide (GlcCer) plays an active role in the regulation of various cellular events. Moreover, GlcCer is also a key modulator of membrane biophysical properties, which might be linked to the mechanism of its biological action. In order to understand the biophysical implications of GlcCer on membranes of living cells, we first studied the effect of GlcCer on artificial membranes containing 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC), sphingomyelin (SM) and cholesterol (Chol).

A Three-Component Assembly Promoted by Boronic Acids Delivers a Modular Fluorophore Platform (BASHY Dyes).

The modular assembly of boronic acids with Schiff-base ligands enabled the construction of innovative fluorescent dyes [boronic acid salicylidenehydrazone (BASHY)] with suitable structural and photophysical properties for live cell bioimaging applications. This reaction enabled the straightforward synthesis (yields up to 99%) of structurally diverse and photostable dyes that exhibit a polarity-sensitive green-to-yellow emission with high quantum yields of up to 0.6 in nonpolar environments.

Tackling the biophysical properties of sphingolipids to decipher their biological roles.

From the most simple sphingoid bases to their complex glycosylated derivatives, several sphingolipid species were shown to have a role in fundamental cellular events and/or disease. Increasing evidence places lipid-lipid interactions and membrane structural alterations as central mechanisms underlying the action of these lipids. Understanding how these molecules exert their biological roles by studying their impact in the physical properties and organization of membranes is currently one of the main challenges in sphingolipid research.