Sorting nexins (SNXs) are a large group of proteins that contain Phox (PX) domain and involve in regulating endocytosis and endosome sorting. SNX7, a member of SNXs family, contains a PX domain and a BAR domain. In zebrafish, SNX7 is a liver-enriched anti-apoptotic protein and indispensible for the liver development. A fragment of SNX7 cDNA ((px-bar)snx7), encoding the PX domain and the BAR domain, was inserted into the expressing vector p28a, transformed into E. coli Rosseta 2 (DE3), and then induced by isopropyl β-D-1-Thiogalactopyranoside (IPTG). After affinity, ion exchange and gel filtration purification, the purity of (PX-BAR)SNX7 reached over 95%. Dynamic light scattering (DLS) experiment indicated that (PX-BAR)SNX7 was homogeneous in solution. Lipid overlay assay showed that (PX-BAR)SNX7 can bind to PtdIns(5)P, PtdIns(4,5)P2 and PtdIns(3,4,5)P3.
Escherichia coli ; metabolism ; Genetic Vectors ; Humans ; Phosphatidylinositols ; metabolism ; Recombinant Proteins ; biosynthesis ; Sorting Nexins ; biosynthesis ; Substrate Specificity

Phospholipids are key components of cellular membrane and signaling. Among cellular phospholipids, phosphoinositides, phosphorylated derivatives of phosphatidylinositol are important as a participant in essential metabolic processes in animals. However, due to its low abundance in cells and tissues, it is difficult to identify the composition of phosphoinositides. Recent advances in mass spectrometric techniques, combined with established separation methods, have allowed the rapid and sensitive detection and quantification of a variety of lipid species including phosphoinositides. In this mini review, we briefly introduce progress in profiling of cellular phosphoinositides using mass spectrometry. We also summarize current progress of matrices development for the analysis of cellular phospholipids using matrix-assisted laser desorption/ionization mass spectrometry. The phosphoinositides profiling and phospholipids imaging will help us to understand how they function in a biological system and will provide a powerful tool for elucidating the mechanism of diseases such as diabetes, cancer and neurodegenerative diseases. The investigation of cellular phospholipids including phosphoinositides using electrospray ionization mass spectrometry and matrix-assisted laser desorption/ionization mass spectrometry will suggest new insights on human diseases, and on clinical application through drug development of lipid related diseases.
Animals ; Humans ; Mass Spectrometry/*methods ; Phosphatidylinositols/*metabolism ; Phospholipids/*metabolism ; Spectrometry, Mass, Electrospray Ionization ; Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization

Objective: To clarify the diagnostic value of magnetic resonance imaging based on liver imaging reporting and data system (LI-RADS) for phosphatidylinositol proteoglycan-3 (GPC3) expression in hepatocellular carcinoma (HCC). Methods: Clinical and pathological data of 95 HCC cases with positive GPC3 expression (+) and 40 HCC cases with negative GPC3 expression (-) were retrospectively analyzed, and their MRI image features based on the 2018 version of LI-RADS were compared. Multivariate logistic regression analysis was used to determine the main predictors of GPC3 expression. Receiver operating characteristic curve was used further to determine the diagnostic efficacy of combined clinical imaging model to predict GPC3 expression. Enumeration data were compared with χ² test or Fisher's exact test. Measurement data were compared using independent samples t-test or Mann-Whitney U-test. Results: There were statistically significant differences between HCC in GPC3 (+) and GPC3(-) group at alpha-fetoprotein (AFP) levels (χ²=31.814, P<0.000 1), and MRI features: capsular enhacement (χ²=4.108, P=0.043), halo type enhancement (χ²=4.847, P=0.028), and lesion apparent dispersion coefficient (ADC) (t=2.552, P=0.011 8). Multivariate regression analysis showed that AFP>20 μg/L (OR=9.358, P<0.000 1) and ADC≤1.404×10^-3 mm²/s (OR=1.003, P=0.017) were independent predictors for GPC3 expression in HCC. The combined model and the area under the curve value for the diagnosis of GPC3(+) in HCC was 0.810, and its diagnostic sensitivity and specificity were 76.8% and 77.5%, respectively. Conclusion: AFP>20 μg/L and ADC≤1.404×10^-3 mm²/s may indicate the expression of GPC3 in HCC, and the combination of the two diagnostic indicators can provide a simple and effective non-invasive diagnostic method for clinical practice.
Biomarkers, Tumor ; Carcinoma, Hepatocellular/pathology* ; Glypicans/metabolism* ; Humans ; Liver Neoplasms/pathology* ; Magnetic Resonance Imaging ; Phosphatidylinositols ; Retrospective Studies ; alpha-Fetoproteins/metabolism*

Macrodactyly is one of the most difficult hand anomalies to treat not only surgically but medically as well. Little is known about the molecular pathways and lipid metabolism of this disease. To elucidate the potential mechanism of macrodactyly progress, we used the bioinformatical analysis including quantile normalization, principal component analysis, heatmap and volcano plot. For the functional bioinformatical study, lipid, lipoprotein and phospholipid metabolism of Kyoto Encyclopedia of Genes and Genomes, Wiki Pathways, and Reactome Pathway were utilized to compare the differentially expressed genes in macrodactyly with control group. We found up-regulation of CDK6 and E2F1, which are associated with the mitotic cell cycle of cancer cells. PIK3CG, associated with cancer and lipid metabolism, was also enriched in macrodactyly. In down-regulated genes, PTEN was highlighted in lipid metabolism, phosphatidylinositol signaling system and insulin signaling. ABCD3, related in peroxisomal import of fatty acids, was also down-regulated. In this study, we predicted the pathogenic candidate genes as well as the potential molecular pathways related to macrodactyly by identifying the signature genes. Signature genes through systems bioinformatical analysis can be utilized to catch the insight of the molecular pathogenesis of macrodactyly.
Cell Cycle ; Computational Biology ; Fatty Acids ; Genome ; Gigantism ; Hand ; Insulin ; Lipid Metabolism* ; Lipoproteins ; Metabolism ; Phosphatidylinositols ; Principal Component Analysis ; Transcriptome* ; Up-Regulation

OBJECTIVETo investigate the effect of Astragalus membranaceus(AM) on vascular circles and the underlying mechanisms.

METHODSThe study was performed with the model of isolate rat thoracic aorta rings in organ bath. When the endothelium of rat thoracic aorta was removed,the effect of accumulated AM on aorta rings in resting tension, or pre-constricted with KCl, or pre-constricted with phenylephrine (PE) was observed. And to explove the mechanism, the aorta rings were incubated with Ca(2+)-free medium alone, or Ca(2+)-free medium plus heparin, or propranolol alone before pre-contraction with PE.

RESULTSAM had no significant effects on aorta rings in resting tension or pre-constricted with KCl. When the concentration of AM was cumulated to 10(-1), 3 x 10(-1),10(0), 3 x 10(0) g/L, it caused concentration-dependent relaxation while aorta rings were pre-constricted with PE(3 x 10(-7)mol/L), compared with the control [(90.4 +/-4.2)% compared with (94.7 +/-2.4)%,(86.1 +/-5.0)% compared with (92.6 +/-3.2)%, (82.3 +/-5.9)% compared with (90.4 +/-3.6) %, (78.3 +/-6.0)% compared with (88.1 +/-4.0)%]. This effect was not inhibited by Ca(2+)-free medium or propranolol alone. However, the effect was attenuated by the co-incubation with heparin and Ca(2+)-free medium [without heparin:(76.2+/-4.3)% compared with (92.3 +/-5.9)%, with heparin: (95.3+/-0.5)% compared with (95.1+/-0.6)%].

CONCLUSIONThe results indicate that AM can relax the rat thoracic aorta rings without endothelium. The mechanism may include the inhibition of intracellular calcium ions release by the 1,4,5-triphosphate inositol-receptor-dependent pathway in vascular smooth muscle cells.

Animals ; Aorta, Thoracic ; cytology ; Astragalus membranaceus ; Calcium ; metabolism ; Drugs, Chinese Herbal ; pharmacology ; In Vitro Techniques ; Male ; Muscle, Smooth, Vascular ; cytology ; Phosphatidylinositols ; metabolism ; Rats ; Rats, Sprague-Dawley ; Vasodilator Agents ; pharmacology

PURPOSE: Estrogen stimulates cell proliferation in breast cancer, the biological effects of which are mediated through two intracellular receptors: estrogen receptor-alpha (ERalpha) and estrogen receptor-beta (ERbeta). However, the actual role of ERs in the proliferative action of estrogen remains to be established. It was recently found that ER activates phosphatidylinositol-3-OH kinase (PI3K), via its binding with the p85 regulatory subunit of PI3K. Therefore, possible mechanisms may include ER-mediated phosphoinositide metabolism, with the subsequent formation of phosphatidylinositol-3, 4, 5-trisphosphate (PIP(3)), which is generated from phosphatidylinositol 4, 5-bisphosphate (PIP(2)) via PI3K activation. The present study has demonstrated that 17b-estradiol (E2) up-regulates PI3K in an ERalpha, but not an ERbeta dependent manner, and also stimulates cell growth in breast cancer cells. METHODS: To study this phenomenon, we treated ER-positive MCF-7 cells and ER-negative MDA-MB-231 cells with 10 nM E2. RESULTS: The treatment of MCF-7 cells with E2 resulted in a marked increase in the expression of PI3K (p85), which was paralleled by increases in the levels of phospho-Akt (Ser-473) and PIP3. These observations were also correlated with increased E2-induced cell proliferation activity. However, no effects of E2 on breast cancer cells were observed in the MDA-MB-231 cell line, indicating the pathway of E2-mediated up-regulation of PI3K/Akt is ERalpha-dependent. CONCLUSION: These results suggest that estrogen activates PI3K/Akt signaling via an ERalpha-dependent mechanism in MCF-7 cells.
Breast Neoplasms* ; Breast* ; Cell Line ; Cell Proliferation ; Estradiol* ; Estrogen Receptor alpha ; Estrogen Receptor beta ; Estrogens* ; MCF-7 Cells ; Metabolism ; Phosphatidylinositol 3-Kinases ; Phosphatidylinositols ; Up-Regulation*

TRPML1 channel is a non-selective group-2 transient receptor potential (TRP) channel with Ca permeability. Located mainly in late endosome and lysosome of all mammalian cell types, TRPML1 is indispensable in the processes of endocytosis, membrane trafficking, and lysosome biogenesis. Mutations of TRPML1 cause a severe lysosomal storage disorder called mucolipidosis type IV (MLIV). In the present study, we determined the cryo-electron microscopy (cryo-EM) structures of Mus musculus TRPML1 (mTRPML1) in lipid nanodiscs and Amphipols. Two distinct states of mTRPML1 in Amphipols are added to the closed state, on which could represent two different confirmations upon activation and regulation. The polycystin-mucolipin domain (PMD) may sense the luminal/extracellular stimuli and undergo a "move upward" motion during endocytosis, thus triggering the overall conformational change in TRPML1. Based on the structural comparisons, we propose TRPML1 is regulated by pH, Ca, and phosphoinositides in a combined manner so as to accommodate the dynamic endocytosis process.
Animals ; Calcium ; metabolism ; Cryoelectron Microscopy ; Endocytosis ; Endosomes ; metabolism ; Gene Expression ; HEK293 Cells ; Humans ; Hydrogen-Ion Concentration ; Lysosomes ; metabolism ; Mice ; Models, Biological ; Mucolipidoses ; genetics ; metabolism ; pathology ; Nanostructures ; chemistry ; ultrastructure ; Phosphatidylinositols ; metabolism ; Transgenes ; Transient Receptor Potential Channels ; chemistry ; genetics ; metabolism

The adapter protein Lamellipodin (Lpd) plays an important role in cell migration. In particular, Lpd mediates lamellipodia formation by regulating actin dynamics via interacting with Ena/VASP proteins. Its RA-PH tandem domain configuration suggests that like its paralog RIAM, Lpd may also mediate particular Ras GTPase signaling. We determined the crystal structures of the Lpd RA-PH domains alone and with an N-terminal coiled-coil region (cc-RA-PH). These structures reveal that apart from the anticipated coiled-coil interaction, Lpd may also oligomerize through a second intermolecular contact site. We then validated both oligomerization interfaces in solution by mutagenesis. A fluorescence-polarization study demonstrated that Lpd binds phosphoinositol with low affinity. Based on our crystallographic and biochemical data, we propose that Lpd and RIAM serve diverse functions: Lpd plays a predominant role in regulating actin polymerization, and its function in mediating Ras GTPase signaling is largely suppressed compared to RIAM.
Actins ; metabolism ; Amino Acid Sequence ; Binding Sites ; Carrier Proteins ; chemistry ; genetics ; metabolism ; Crystallography, X-Ray ; Humans ; Membrane Proteins ; chemistry ; genetics ; metabolism ; Molecular Sequence Data ; Mutagenesis ; Phosphatidylinositols ; metabolism ; Polymerization ; Protein Binding ; Protein Structure, Tertiary ; Recombinant Proteins ; biosynthesis ; chemistry ; genetics ; Signal Transduction ; ras Proteins ; metabolism

Growth factor stimulation induces Y783 phosphorylation of phosphoinositide-specific PLC-gamma1, and the subsequent activation of this enzyme in a cellular signaling cascade. Previously, we showed that a double point mutation, Y509A/F510A, of PLC-gamma1, abolished interactions with translational elongation factor 1-alpha. Here, we report that the Y509A/F510A mutant PLC-gamma1 displayed extremely high levels of Y783 phosphorylation and enhanced catalytic activity, compared to wild-type PLC-gamma1, upon treatment of COS7 cells with EGF. In quiescent COS7 cells, the Y509A/F510A mutant PLC-gamma1 exhibited a constitutive hydrolytic activity, whereas the wild-type counterpart displayed a basal level of activity. Upon treatment of COS7 cells with EGF, the Y783F mutation in Y509A/F510A PLC-gamma1 (Y509A/F510A/Y783F triple mutant) cells also led to an enhanced catalytic activity, whereas Y783F mutation alone displayed a basal level of activity. Our results collectively suggest that the Y509A/F510A mutant is more susceptible to receptor tyrosine kinase-induced Y783 phosphorylation than is wild-type PLC-gamma1, but no longer requires Y783 phosphorylation step for the Y509A/F510A mutant PLC-gamma1 activation in vivo.
Amino Acid Substitution/drug effects/*genetics ; Animals ; COS Cells ; Cercopithecus aethiops ; Enzyme Activation/drug effects ; Epidermal Growth Factor/*pharmacology ; Hydrolysis/drug effects ; Mutant Proteins/metabolism ; Phosphatidylinositols/*metabolism ; Phospholipase C gamma/*genetics/metabolism ; Phosphorylation/drug effects ; Phosphotyrosine/*metabolism ; Point Mutation/*genetics ; Rats

OBJECTIVETo study cell membrane phospholipid variation and protein kinase C (PKC) isoenzyme expression and their effects on hepatic metastasis of large intestinal carcinoma.

METHODSHigh function liquid chromatography was used to separate and detect cell membrane phospholipids of phosphatidylinosital (PI), phosphatidylserine (PS), phosphatidylethanolamine (PE) and phosphatidylcholine (PC) in primary foci, paratumor intestine mucosa and hepatic metastasis of large intestinal carcinomas. And mRNA expression levels of PKC-alpha, -beta II, -delta, -epsilon, -lambda, -zeta isoenzymes were detected using QRT-PCR technique.

RESULTSFifty-eight cases of colorectal cancer were examined.

CONTENTSof PI, PC and PE in primary foci and hepatic metastasis were higher than those in paratumor mucosa. PE content in hepatic metastasis was much higher than that in primary foci (t = 98.88, P < 0.01). But PI and PC contents had no significant differences between primary and hepatic metastasis (t = 1.73, 1.36, P > 0.05). PKC-beta II, -delta, -epsilon, -lambda, -zeta expression were enhanced in primary foci and hepatic metastasis, but PKC-alpha level decreased in comparison with paratumor mucosa. And PKC-delta, -epsilon, -lambda, -zeta levels in hepatic metastasis were higher than those in primary foci (t = 4.31, P < 0.05). PI and PC had positive correlations with PKC-beta II expression. PE had positive correlations with PKC-delta, -epsilon, -lambda, -zeta, but a negative correlation with PKC-alpha.

CONCLUSIONSThe increases of PI and PC and PKC-alpha/PKC-beta II ratio change are related with colorectal cancer genesis. High content of PE and enhanced expression of PKC-delta, -epsilon, -lambda, -zeta isoenzymes and decreased PKC-alpha level improved hepatic metastasis of large intestinal carcinoma.

Adult ; Aged ; Aged, 80 and over ; Chromatography, Liquid ; Female ; Humans ; Intestinal Neoplasms ; pathology ; Isoenzymes ; genetics ; Liver Neoplasms ; secondary ; Male ; Membrane Lipids ; analysis ; Middle Aged ; Phosphatidylcholines ; analysis ; Phosphatidylethanolamines ; analysis ; Phosphatidylinositols ; analysis ; Phosphatidylserines ; analysis ; Protein Kinase C ; genetics ; RNA, Messenger ; genetics ; metabolism ; Reverse Transcriptase Polymerase Chain Reaction