[en] N-ethylmaleimide-sensitive factor attachment protein receptor (SNARE) proteins are involved in the fusion of vesicles with their target membranes. R-SNARE protein Ykt6 is one of the most conserved SNARE in eukaryotes. The conformational state of Ykt6 is regulated by the lipidations at its C-terminal motif. Previous studies show that the binding of dodecylphosphocholine (DPC) can stabilize a closed conformation of rat Ykt6 (rYkt6) and mimic the farnesylated rYkt6. Despite this model, the detailed conformational dynamics of Ykt6 is still unclear. Here, we combined smFRET and MD simulation to demonstrate that the un-lipidated rYkt6 adopts five major conformational states. DPC binding shifts the conformational distribution toward the more closed states. At the same time, there remain considerable fractions of open and semi-open conformations in the presence of DPC. These newly revealed dynamic features of rYkt6 are consistent with its unique functional diversity in neuronal cells.

[en] Highlights: • We reported a highly potent strategy for intracellular protein delivery. • A branching poly-E tag mediated the entrapment of proteins into liposomes. • The resultant protein-lipid complexes entered into cytosol with a high efficiency. • The strategy maintained protein's biological activity. Intracellular protein delivery is of significance for cellular protein analysis and therapeutic development, but remains challenging technically. Herein, we report a general and highly potent strategy for intracellular protein delivery based on commercially available cationic lipids. In this strategy, a designed double branching poly-glutamate tag is site-specifically attached onto the C-terminal of protein cargos via expressed protein ligation (EPL), which mediates the entrapment of proteins into cationic liposomes driven by electrostatic interaction. The resultant protein-lipid complexes can enter into cytosol with a high efficiency even at the low protein concentration while maintaining protein's biological activity.

[en] Although phosphoenolpyruvate carboxylases (PEPCs) are reported to be involved in fatty acid accumulation, nitrogen assimilation, and salt and drought stresses, knowledge regarding PEPC gene functions is still limited, particularly in peanuts (Arachis hypogaea L.). In this study, the antisense expression of the peanut PEPC isoform 1 (AhPEPC1) gene increased the lipid content by 5.7%–10.3%. This indicated that AhPEPC1 might be related to plant lipid accumulation. The transgenic plants underwent more root elongation than the wild-type under salinity stress. Additionally, the specific down regulation of the AhPEPC1 gene improved the salt tolerance in peanuts. This is the first report on the role of PEPC in lipid accumulation and salt tolerance in peanuts.

[en] Exosomes contain cargoes of proteins, lipids, micro-ribonucleic acids, and functional messenger RNAs, and they play a key role in cell-to-cell communication and hold valuable information about biological processes such as disease pathology. To harvest their potentials in disease diagnostics, prognostics, and therapeutics, exosome isolation is a crucial first step in providing pure and intact samples for both research and clinical purposes. Unfortunately, conventional methods for exosome separation suffer from low purity, low capture efficiency, long processing time, large sample volume requirement, the need for dedicated equipment and trained personnel, and high cost. In the last decade, microfluidic devices, especially those that incorporate nanostructures, have emerged as superior alternatives for exosome isolation and detection. In this review, we examine microfluidic platforms, dividing them into six categories based on their capture mechanisms: passive-structure-based affinity, immunomagnetic-based affinity, filtration, acoustofluidics, electrokinetics, and optofluidics. Here, we start out exploring the research and clinical needs that translate into important performance parameters for new exosome isolation designs. Then, we briefly introduce the conventional methods and discuss how their failure to meet those performance standards sparks an intense interest in microfluidic device innovations. The essence of this review is to lead an in-depth discussion on not only the technicality of those microfluidic platforms, but also their strengths and weaknesses with regards to the performance parameters set forth. To close the conversation, we call for the inclusion of exosome confirmation and contamination evaluation as part of future device development and performance assessment process, so that collectively, efforts towards microfluidics and nanotechnology for exosome isolation and analysis may soon see the light of real-world applications. (topical review)

[en] Membrane tubes are important functional elements for living cells. Experiments have found that membrane tubes can be extracted from giant lipid vesicles by groups of kinesin. How these motors cooperate in extracting the membrane tube is a very important issue but still unclear so far. In this paper, we propose a cooperation mechanism called two-track-dumbbell model, in which kinesin is regarded as a dumbbell with an end (tail domain) tethered on the Quid-like membrane and the other end (head domain) stepping on the microtubule. Taking account of the elasticity of kinesin molecule and the excluded volume effect of both the head domain and the tail domain of kinesin, which are not considered in previous models, we simulate the growth process of the membrane tube pulled by kinesin motors. Our results indicate that in the case of strong or moderate exclusion of motor tails, the average number of motors pulling the tube can be as high as 9 and thus motors moving along a single microtubule protofilament can generate enough force to extract membrane tubes from vesicles. This result is different from previous studies and may be tested by future experiments. (interdisciplinary physics and related areas of science and technology)

[en] Coronaviruses (CoVs) can cause life-threatening respiratory diseases. Their infectious entry requires viral spike (S) proteins, which attach to cell receptors, undergo proteolytic cleavage, and then refold in a process that catalyzes virus-cell membrane fusion. Fusion-inhibiting peptides bind to S proteins, interfere with refolding, and prevent infection. Here we conjugated fusion-inhibiting peptides to various lipids, expecting this to secure peptides onto cell membranes and thereby increase antiviral potencies. Cholesterol or palmitate adducts increased antiviral potencies up to 1000-fold. Antiviral effects were evident after S proteolytic cleavage, implying that lipid conjugates affixed the peptides at sites of protease-triggered fusion activation. Unlike lipid-free peptides, the lipopeptides suppressed CoV S protein-directed virus entry taking place within endosomes. Cell imaging revealed intracellular peptide aggregates, consistent with their endocytosis into compartments where CoV entry takes place. These findings suggest that lipidations localize antiviral peptides to protease-rich sites of CoV fusion, thereby protecting cells from diverse CoVs. - Graphical abstract: Early and late CoV entry is depicted as virus-cell fusion at cell surfaces and endosomes, respectively. Scissors represent virus-activating proteases. The HR2 peptides are in green, with lipid-free peptides as monomers (middle panel) and lipopeptides as micellar aggregates (right panel). - Highlights: • Lipidation increases antiviral activities of CoV fusion-inhibiting peptides. • Fusion-inhibiting peptides target proteolytically-triggered CoV spike proteins. • Lipidated peptides suppress CoVs that are occluded within endosomes before cytosolic entry.

[en] Highlights: • Adipogenic differentiation induces CRY1 expression. . • Knockdown of CRY1 inhibits adipogenic differentiation and adipogenesis-specific gene expression. • Knockdown of CRY1 activates canonical Wnt/β-catenin signaling pathway. Cryptochrome gene 1(CRY1) is a member of circadian clock genes, which play an important role in adipocyte biology. CRY1 was reported to be related with the lipid metabolism, but the molecule mechanism of CRY1 in regulating the adipogenesis remains unclear. Here we report that CRY1 is a key regulator in adipogenic differentiation. We found that the expression levels of CRY1 in 3T3-L1 cells and C3H10T1/2 cells gradually increased during the process of adipogenic differentiation. Knockdown of endogenous CRY1 significantly inhibited the expression of adipogenic markers and lipid droplet formation in cells under adipogenic induction. In addition, knockdown of endogenous CRY1 promoted the expression and nuclear accumulation of β-catenin, the critical signal molecular in the canonical canonical Wnt signaling pathway, suggesting the regulation effect of CRY1 in adipogenesis was mediated by canonical Wnt/β-catenin signaling. Taken together, our study suggests that CRY1 regulates adipogenic differentiation through modulating the canonical Wnt/β-catenin signaling pathway.

[en] Highlights: • Advances in mass spectrometry have expanded our knowledge of lipids. • Targeted and non-targeted lipidomics are powerful strategies with distinct features. • We briefly review the applications of these lipidomics strategies in lipid research. • Current limitations and challenges in lipidomics are also discussed. Recent advances in mass spectrometry have expanded our knowledge of lipids and lipid metabolic pathways involved in many (patho)physiological events. Targeted and non-targeted lipidomics are powerful analytical strategies with distinct features, and a combination of these two approaches is often employed to maximize the coverage of lipid species detected and quantified in complex biological matrices. This review briefly summarizes the applications of targeted and non-targeted lipidomics, mainly focusing on electrospray ionization–liquid chromatography–tandem mass spectrometry (ESI–LC–MS/MS), along with recent technical advances in the field. Current limitations and challenges in lipidomics and possible solutions are also discussed.

[en] Highlights: • SREBP1 is overexpressed in ccRCC cell lines and positively correlated with NF-κB activation. • SREBP1 promotes and is require for lipid desaturation in ccRCC. • SREBP1-driven lipid desaturation promotes NF-κB activation in ccRCC. • SREBP1-driven lipid desaturation and NF-κB activation is required for ccRCC cell growth. Clear cell renal cell carcinoma (ccRCC), the most common type of kidney cancers, is an incurable and lethal disease. Although great progresses have been made in understanding the mechanism of ccRCC, metabolic reprogramming in ccRCC remains largely unclear. Here, we showed that lipid desatutation might be a metabolic hallmark of ccRCC. We demonstrated sterol regulatory element-binding protein 1 (SREBP1) is overexpressed in ccRCC cell lines and positively correlated with NF-κB activation. Further, SREBP1 is required for lipid desaturation and cell growth in ccRCC. Mechanistically, we demonstrated that SREBP1-driven lipid desaturation promotes NF-κB activation. Our finding reveals a crucial roles for SREBP1 in lipid desaturation of ccRCC through regulation of NF-κB signaling, which provides not only new insights in regulatory mode of NF-κB signaling but also a novel target for potential metabolic therapies.

No abstract available