Bridge-Like Lipid Transfer Proteins (BLTPs) in C. elegans: From Genetics to Structures and Functions.

In eukaryotic cells, lipid transfer can occur at membrane contact sites (MCS) to facilitate the exchange of various lipids between two adjacent cellular organelle membranes. Lipid transfer proteins (LTPs), including shuttle LTP or bridge-like LTP (BLTP), transport lipids at MCS and are critical for diverse cellular processes, including lipid metabolism, membrane trafficking, and cell signaling. BLTPs (BLTP1-5, including the ATG2 and VPS13 family proteins) contain lipid-accommodating hydrophobic repeating ß-groove (RBG) domains that allow the bulk transfer of lipids through MCS. Compared with vesicular lipid transfer and shuttle LTP, BLTPs have been only recently identified. Their functions and regulatory mechanisms are currently being unraveled in various model organisms and by diverse approaches. In this review, we summarize the genetics, structural features, and biological functions of BLTP in the genetically tractable model organism C. elegans. We discuss our recent studies and findings on C. elegans LPD-3, a prototypical megaprotein ortholog of BLTP1, with identified lipid transfer functions that are evolutionarily conserved in multicellular organisms and in human cells. We also highlight areas for future research of BLTP using C. elegans and complementary model systems and approaches. Given the emerging links of BLTP to several human diseases, including Parkinson's disease and Alkuraya-Kucinskas syndrome, discovering evolutionarily conserved roles of BLTPs and their mechanisms of regulation and action should contribute to new advances in basic cell biology and potential therapeutic development for related human disorders.

Structure and mechanism of the alkane-oxidizing enzyme AlkB.

Alkanes are the most energy-rich form of carbon and are widely dispersed in the environment. Their transformation by microbes represents a key step in the global carbon cycle. Alkane monooxygenase (AlkB), a membrane-spanning metalloenzyme, converts straight chain alkanes to alcohols in the first step of the microbially-mediated degradation of alkanes, thereby playing a critical role in the global cycling of carbon and the bioremediation of oil. AlkB biodiversity is attributed to its ability to oxidize alkanes of various chain lengths, while individual AlkBs target a relatively narrow range. Mechanisms of substrate selectivity and catalytic activity remain elusive. Here we report the cryo-EM structure of AlkB, which provides a distinct architecture for membrane enzymes. Our structure and functional studies reveal an unexpected diiron center configuration and identify molecular determinants for substrate selectivity. These findings provide insight into the catalytic mechanism of AlkB and shed light on its function in alkane-degrading microorganisms.

Structure and thiazide inhibition mechanism of the human Na-Cl cotransporter.

The sodium-chloride cotransporter (NCC) is critical for kidney physiology1. The NCC has a major role in salt reabsorption in the distal convoluted tubule of the nephron2,3, and mutations in the NCC cause the salt-wasting disease Gitelman syndrome4. As a key player in salt handling, the NCC regulates blood pressure and is the target of thiazide diuretics, which have been widely prescribed as first-line medications to treat hypertension for more than 60 years5-7. Here we determined the structures of human NCC alone and in complex with a commonly used thiazide diuretic using cryo-electron microscopy. These structures, together with functional studies, reveal major conformational states of the NCC and an intriguing regulatory mechanism. They also illuminate how thiazide diuretics specifically interact with the NCC and inhibit its transport function. Our results provide critical insights for understanding the Na-Cl cotransport mechanism of the NCC, and they establish a framework for future drug design and for interpreting disease-related mutations.

A conserved megaprotein-based molecular bridge critical for lipid trafficking and cold resilience.

Cells adapt to cold by increasing levels of unsaturated phospholipids and membrane fluidity through conserved homeostatic mechanisms. Here we report an exceptionally large and evolutionarily conserved protein LPD-3 in C. elegans that mediates lipid trafficking to confer cold resilience. We identify lpd-3 mutants in a mutagenesis screen for genetic suppressors of the lipid desaturase FAT-7. LPD-3 bridges the endoplasmic reticulum (ER) and plasma membranes (PM), forming a structurally predicted hydrophobic tunnel for lipid trafficking. lpd-3 mutants exhibit abnormal phospholipid distribution, diminished FAT-7 abundance, organismic vulnerability to cold, and are rescued by Lecithin comprising unsaturated phospholipids. Deficient lpd-3 homologues in Zebrafish and mammalian cells cause defects similar to those observed in C. elegans. As mutations in BLTP1, the human orthologue of lpd-3, cause Alkuraya-Kucinskas syndrome, LPD-3 family proteins may serve as evolutionarily conserved highway bridges critical for ER-associated non-vesicular lipid trafficking and resilience to cold stress in eukaryotic cells.

Structural mechanism of protein recognition by the FW domain of autophagy receptor Nbr1.

Neighbor of BRCA1 (Nbr1) is a conserved autophagy receptor that provides cargo selectivity to autophagy. The four-tryptophan (FW) domain is a signature domain of Nbr1, but its exact function remains unclear. Here, we show that Nbr1 from the filamentous fungus Chaetomium thermophilum uses its FW domain to bind the α-mannosidase Ams1, a cargo of selective autophagy in both budding yeast and fission yeast, and delivers Ams1 to the vacuole by conventional autophagy in heterologous fission yeast. The structure of the Ams1-FW complex was determined at 2.2 Å resolution by cryo-electron microscopy. The FW domain adopts an immunoglobulin-like ß-sandwich structure and recognizes the quaternary structure of the Ams1 tetramer. Notably, the N-terminal di-glycine of Ams1 is specifically recognized by a conserved pocket of the FW domain. The FW domain becomes degenerated in fission yeast Nbr1, which binds Ams1 with a ZZ domain instead. Our findings illustrate the protein binding mode of the FW domain and reveal the versatility of Nbr1-mediated cargo recognition.

Pharmacological Properties of Ginsenoside Re.

Ginsenoside Re is a protopanaxatriol-type saponin extracted from the berry, leaf, stem, flower bud, and root of Panax ginseng. In recent years, ginsenoside Re (Re) has been attracting attention as a dietary phytochemical. In this review, studies on Re were compiled by searching a combination of keywords, namely "pharmacology," "pharmacokinetics," and "toxicology," in the Google Scholar, NCBI, PubMed, and Web of Science databases. The aim of this review was to provide an exhaustive overview of the pharmacological activities, pharmacokinetics, and toxicity of Re, focusing on clinical evidence that has shown effectiveness in specific diseases, such as diabetes mellitus, nervous system diseases, inflammation, cardiovascular disease, and cancer. Re is also known to eliminate virus, enhance the immune response, improve osteoporosis, improve skin barrier function, enhance intracellular anti-oxidant actions, regulate cholesterol metabolism, alleviate allergic responses, increase sperm motility, reduce erectile dysfunction, promote cyclic growth of hair follicles, and reduce gastrointestinal motility dysfunction. Furthermore, this review provides data on pharmacokinetic parameters and toxicological factors to examine the safety profile of Re. Such data will provide a theoretical basis and reference for Re-related studies and future applications.

Analysis on Value of Applying Serum miR-144 and miR-221 Levels in Diagnosing Atherosclerosis.

OBJECTIVE: To explore the value of serum miR-144 and miR-221 in diagnosing atherosclerosis (AS). METHODS: The clinical data of 52 AS patients treated in the department of cardiovascular medicine of our hospital from August 2019 to August 2020 were retrospectively analyzed, and 53 healthy persons were selected from the physical examination center at the same period as the control group. By measuring the indicators including the serum vascular endothelial growth factor (VEGF), superoxide dismutase (SOD), miR-144, and miR-221 in patients of both groups, their value of diagnosing AS was analyzed. RESULTS: Compared with the control group, the AS group obtained significantly higher serum miR-221 and miR-144 expression levels (P < 0.001), significantly higher mean serum homocysteine (Hcy) level value (P < 0.001), lower mean serum SOD level (P < 0.001), and significantly higher level values of serum VEGF, nuclear factor-kappaB (NF-kB), and transforming growth factor-ß (TGF-ß) (P < 0.001), and the area under ROC curve, sensitivity, and specificity of combining miR-221 with miR-144 were significantly higher than those of single diagnosis. CONCLUSION: Serum miR-221 and miR-144 expression levels are increased in AS patients, and combining the two indicators in diagnosis is more accurate and can provide an accurate basis for diagnosis and condition assessment of AS.

Growth and Optical Properties of the Whole System of Li(Mn1-x,Nix)PO4 (0 ≤ x ≤ 0.5) Single Crystals.

A series of single crystals of Li(Mn1-x,Nix)PO4 (x = 0.00, 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.08, 0.10, 0.15, 0.20, and 0.50) have been grown to large sizes up to 5 mm in diameter and 120 mm in length using the floating zone method for the first time. The comprehensive characterizations of the as-grown crystals were performed before further physical property measurements. The composition of the grown crystals was determined by energy-dispersive X-ray spectroscopy. The crystal structures were characterized by the X-ray powder diffraction method with a GSAS fitting for structural refinement, which reveals a high phase purity of the as-obtained crystals. The polarized microscopic images and Laue patterns prove the excellent quality of the single crystals. Oriented cuboids with sizes of 2.7 × 3.8 × 2.1 mm3 along the a, b, and c crystalline directions were cut and polished for further anisotropic magnetic and transparent measurements. We also first proposed a new potential application in the non-linear optical (NLO) and laser generation application for LiMPO4 (M = transition metal) materials. The optical and laser properties, such as the absorption spectra and the second harmonic generation (SHG), have been investigated and have furthermore confirmed the good quality of the as-grown single crystals.

Corosolic acid ameliorates non-alcoholic steatohepatitis induced by high-fat diet and carbon tetrachloride by regulating TGF-ß1/Smad2, NF-κB, and AMPK signaling pathways.

Hawthorn (Crataegus pinnatifida Bunge. var. major) is an edible and medicinal fruit that is very common in food and traditional Chinese medicine. Corosolic acid (CA), a pentacyclic triterpenoid, which is an active component of hawthorn (Crataegus pinnatifida Bunge. var. major), has been exhibiting various pharmacological activities such as antidiabetic, antibacterial, anticancer, antiinflammatory, and antioxidant effects. The study aimed to evaluate the effect of CA on non-alcoholic steatohepatitis (NASH) in mice induced by 60 kcal% high-fat diet (HFD) and carbon tetrachloride (CCl4 ). CA lowered liver index and serum AST, ALT, TG, and TC levels compared to those in the model group. Histological analyses of the liver tissues of mice treated with CA revealed significantly decreased number of lipid droplets and alleviated inflammation and fibrosis. CA inhibited the transcripts of pro-fibrogenic markers (including α-SMA, collagen I, and TIMP-1) and the levels of pro-inflammatory cytokines (including TNF-α, IL-1ß, caspase-1, and IL-6) associated with hepatic fibrosis, and NF-κB translocation and TGF-ß1/Smad2 and AMPK pathways. In addition, CA reduced lipid accumulation via the regulation of AMPK and NF-κB activation in FFA-induced steatotic HepG2 cells. CA also decreased α-SMA, collagen I expressions, and Smad2 phosphorylation, which were reduced by TGF-ß1 treatment in LX2 cells. Our results suggested that CA ameliorated NASH through regulating TGF-ß1/Smad2, NF-κB, and AMPK signaling pathways, and CA could be developed as a potential health functional food or therapeutic agent for NASH patients.

Molecular and structural mechanisms of ZZ domain-mediated cargo selection by Nbr1.

In selective autophagy, cargo selectivity is determined by autophagy receptors. However, it remains scarcely understood how autophagy receptors recognize specific protein cargos. In the fission yeast Schizosaccharomyces pombe, a selective autophagy pathway termed Nbr1-mediated vacuolar targeting (NVT) employs Nbr1, an autophagy receptor conserved across eukaryotes including humans, to target cytosolic hydrolases into the vacuole. Here, we identify two new NVT cargos, the mannosidase Ams1 and the aminopeptidase Ape4, that bind competitively to the first ZZ domain of Nbr1 (Nbr1-ZZ1). High-resolution cryo-EM analyses reveal how a single ZZ domain recognizes two distinct protein cargos. Nbr1-ZZ1 not only recognizes the N-termini of cargos via a conserved acidic pocket, similar to other characterized ZZ domains, but also engages additional parts of cargos in a cargo-specific manner. Our findings unveil a single-domain bispecific mechanism of autophagy cargo recognition, elucidate its underlying structural basis, and expand the understanding of ZZ domain-mediated protein-protein interactions.

The Effect of Echocardiography Based on Lipid Nano Contrast Agent on Cardiology Patients with Heart Failure and Atrial Fibrillation.

This paper discusses the effect and evaluation of echocardiography based on lipid nano contrast agent on patients with heart failure and atrial fibrillation in cardiology department, providing reference for clinical diagnosis and treatment. Fifty two patients with diastolic heart failure diagnosed by echocardiography were selected for routine echocardiographic examination after optimizing the drug treatment scheme, and then the patients underwent treadmill exercise test and stress echocardiography evaluation. The results of conventional echocardiography and stress echocardiography after treatment were compared with those before treatment, and the clinical parameters and biochemical indexes before and after treatment were compared. Results after treatment, the clinical symptoms of the patients improved, the level of NT proBNP in the N-terminal forebrain decreased significantly, and the exercise tolerance increased significantly. Compared with the conventional echocardiography before and after treatment, the left ratio and e' value of stress echocardiography after treatment increased significantly, while E/e' decreased significantly. There was no significant difference in the indexes of general echocardiography before and after treatment. After treatment, positively correlated with the ratio of peak a to peak E. The results show that the sensitivity of stress echocardiography to evaluate ischemic diastolic heart failure has been improved, and some indexes have clinical significance. Compared with conventional echocardiography, it can effectively evaluate the therapeutic effect of drugs.

Cryo-EM structure of fission yeast tetrameric α-mannosidase Ams1.

Fungal α-mannosidase Ams1 and its mammalian homolog MAN2C1 hydrolyze terminal α-linked mannoses in free oligosaccharides released from misfolded glycoproteins or lipid-linked oligosaccharide donors. Ams1 is transported by selective autophagy into vacuoles. Here, we determine the tetrameric structure of Ams1 from the fission yeast Schizosaccharomyces pombe at 3.2 Å resolution by cryo-electron microscopy. Distinct from a low resolution structure of S. cerevisiae Ams1, S. pombe Ams1 has a prominent N-terminal tail that mediates tetramerization and an extra ß-sheet domain. Ams1 shares a conserved active site with other enzymes in glycoside hydrolase family 38, to which Ams1 belongs, but contains extra N-terminal domains involved in tetramerization. The atomic structure of Ams1 reported here will aid understanding of its enzymatic activity and transport mechanism.

Corosolic Acid Attenuates Hepatic Lipid Accumulation and Inflammatory Response via AMPK/SREBPs and NF-κB/MAPK Signaling Pathways.

Corosolic acid (CA) is the main active component of Lagetstroemia speciosa and has been known to serve as several different pharmacological effects, such as antidiabetic, anti-oxidant, and anticancer effects. In this study, effects of CA on the hepatic lipid accumulation were examined using HepG2 cells and tyloxapol (TY)-induced hyperlipidemia ICR mice. CA significantly inhibited hepatic lipid accumulation via inhibition of SREBPs, and its target genes FAS, SCD1, and HMGCR transcription in HepG2 cells. These effects were mediated through activation of AMPK, and these effects were all abolished in the presence of compound C (CC, an AMPK inhibitor). In addition, CA clearly alleviated serum ALT, AST, TG, TC, low-density lipoprotein cholesterol (LDL-C), and increased high-density lipoprotein cholesterol (HDL-C) levels, and obviously attenuated TY-induced liver steatosis and inflammation. Moreover, CA significantly upregulated AMPK, ACC, LKB1 phosphorylation, and significantly inhibited lipin1, SREBPs, TNF-α, F4/80, caspase-1 expression, NF-κB translocation, and MAPK activation in TY-induced hyperlipidemia mice. Our results suggest that CA is a potent antihyperlipidemia and antihepatic steatosis agent and the mechanism involved both lipogenesis and cholesterol synthesis and inflammation response inhibition via AMPK/SREBPs and NF-κB/MAPK signaling pathways.

Fluorescent gold nanoclusters based photoelectrochemical sensors for detection of H2O2 and glucose.

In this work, low-toxicity fluorescent gold nanoclusters (AuNCs) based photoelectrochemical sensors were developed for H2O2 and glucose detection. Herein, the processes used to fabricate the sensors and the photoelectrochemical performances of the sensors under different conditions were presented. Based on the energy band levels of the AuNCs and electron tunneling processes, a detailed photoelectrochemical sensing model was given. The designed sensors were then used for H2O2 and glucose detection without any extra modification of the AuNCs or complex enzyme immobilization. The results demonstrate that the AuNCs allow for H2O2 sensing based on their capacity for both fluorescence and catalysis. Indeed, it was observed that H2O2 was catalyzed by the AuNCs and reduced by photoinduced electrons derived from excited AuNCs. Furthermore, an enhancement in photocurrent amplitude followed the increase in the concentrations of H2O2 and glucose. The effects of the types of ligands surrounding the AuNCs and the applied potential on the output photocurrent were well studied to optimize the measurement conditions. The sensitivity and LOD of MUA-AuNCs at -500 mV were 4.33 nA/mM and 35 µM, respectively. All experimental results indicated that AuNCs could not only serve as a promising photoelectrical material for building the photoelectrochemical biosensors but as catalysts for H2O2 sensing.

Diode-pumped laser and self-frequency-doubling properties of a Nd3+:Na3La9O3(BO3)8 crystal.

We report efficient, diode-pumped, self-frequency doubling (SFD) in the newly developed laser crystal Nd3+:Na3La9O3(BO3)8 (Nd:NLBO). More than 730 mW of fundamental output power at 1072 nm was achieved with a slope efficiency of 16.2%. With incident pump power of 8 W, 29 mW of green cw laser emission at 536 nm was observed with proper phase matching. This initial performance and the good optical properties of the crystalline host are encouraging for the development of a high power diode-pumped SFD visible light laser source.

New nonlinear optical crystal: NaBa4Al2B8O18Cl3.

Single crystals of NaBa(4)Al(2)B(8)O(18)Cl(3) have been grown with sizes up to 34 × 34 × 16 mm(3) from the NaF-LiCl flux by the top-seeded solution growth method. The compound crystallizes in the tetragonal system, space group P4(2)nm, with a = 12.0480 (16) Å, c = 6.8165 (11) Å, α = ß = γ = 90°, and two formula units per cell. The NaBa(4)Al(2)B(8)O(18)Cl(3) compound is built up of infinite anionic groups of [AlB(4)O(12)](9-) formed by two BO(4) tetrahedra, one AlO(4) tetrahedra, and two BO(3) triangles. Optical properties including ultraviolet transmission, IR spectrum, and second-harmonic generation of NaBa(4)Al(2)B(8)O(18)Cl(3) crystals were reported. Refractive indices were measured by the minimum deviation technique and fitted to the Sellmeier equations. Thermal properties such as the DSC and thermal expansion were reported. The mechanical properties including the hardness, density, and chemical stability were also reported.

High-efficiency third harmonic generation at 355nm based on La2CaB10O19.

La2CaB10O19 (LCB) crystals with size up to 55 × 35 × 25 mm3 have been grown by the top-seeded solution growth (TSSG) method. The refractive indices were accurately measured over the full transmission range, and the second-order nonlinear optical coefficients were determined by the Maker fringe technique. The phase-matching(PM) conditions were calculated for third-harmonic generation (THG) at different wavelengths. The THG experiments for type I and type II LCB crystals were performed. For type I LCB, a 355 nm UV light output of 5.0 mW corresponding to the conversion efficiency of 28.3% was generated under a picosecond Nd:YAG laser, and 16 W with the efficiency of 17.5% was generated under a nanosecond 1064 nm pumping source. For type II LCB, 3.5mW THG output with conversion efficiency of 21.1% was obtained under a picosecond Nd:YAG laser, and 7.6 W with the efficiency of 7.9% was generated under a nanosecond 1064 nm pumping source. The results indicated that the LCB crystal is a promising UV nonlinear optical material because of its good THG performance and nonhygroscopicity.

4-{2-[4-(Dimethyl-amino)-phen-yl]ethen-yl}-1-methyl-pyridinium 2,4,6-trimethyl-benzene-sulfonate monohydrate.

In the crystal structure of the title organic salt, C(16)H(19)N(2) (+)·C(9)H(11)O(3)S(-)·H(2)O, the cations pack head-to-tail within a sheet and are aligned in opposite directions in neighboring sheets. The benzene ring of the anion makes an angle of 76.99 (6)° with the plane of the cationic chromophore. The cations are situated in the ab plane, whereas the benzene rings of the anions lie in the ac plane.

Growth and optical properties of a new nonlinear Na(3)La(9)O(3)(BO(3))(8) crystal.

New nonlinear crystals Na(3)La(9)O(3)(BO(3))(8) (abbreviated as NLBO) with desired morphologies, high quality and weight exceeding 40g have been grown along different directions, such as [001], [110], and [100], by top-seeded solution growth(TSSG) method. The refractive indices were accurately measured over the full transmission range, and the second-order nonlinear optical coefficients were determined by the Maker fringe technique. The optimal phase-matching (PM) conditions and the corresponding effective nonlinear coefficient were calculated for second harmonic generation (SHG) at different wavelengths. In order to confirm the correctness of our calculation, we also performed the SHG experiments under 1064 and 800 nm pumping, respectively. In addition, we directly compared the SHG performance of NLBO with that of LBO under the same experimental conditions with the 1064 nm pumping source. As the results, a conversion efficiency of 58.3% at 532 nm was obtained for NLBO, and whereas only 21.5% was obtained for LBO, indicating that NLBO is a highly attractive nonlinear material for frequency conversion of pulses into the visible and ultraviolet.

Nonapotassium trialuminium hexa-phosphate.

In the title compound, K(9)Al(3)(PO(4))(6), the anionic substructure is built of inter-linked [PO(4)] and [AlO(4)] tetra-hedra. Each O atom of the [AlO(4)] tetra-hedron is common to a positionally different [PO(4)] tetra-hedron; thus, each [AlO(4)] tetra-hedron is surrounded by four positionally different [PO(4)] tetra-hedra. On the other hand, each [PO(4)] tetra-hedron shares its two O atoms with two positionally different [AlO(4)] tetra-hedra; the other two phosphate O atoms are terminal ones coordinated by K atoms. The terminal O atoms are usually closer to the K atoms than the bridging O atoms between the [AlO(4)] and [PO(4)] tetra-hedra. There are nine symmetry-independent K atoms in the structure. The coordination numbers of the K atoms are 6 or 7 or 8 up to a distance of 3.31 Å. There are channels in the anionic substructure oriented along the [10] direction that are filled by K atoms.