Transient receptor potential canonical 4 (TRPC4) channel is a nonselective calcium-permeable cation channels. In intestinal smooth muscle cells, TRPC4 currents contribute more than 80% to muscarinic cationic current (mIcat). With its inward-rectifying current-voltage relationship and high calcium permeability, TRPC4 channels permit calcium influx once the channel is opened by muscarinic receptor stimulation. Polyamines are known to inhibit nonselective cation channels that mediate the generation of mIcat. Moreover, it is reported that TRPC4 channels are blocked by the intracellular spermine through electrostatic interaction with glutamate residues (E728, E729). Here, we investigated the correlation between the magnitude of channel inactivation by spermine and the magnitude of channel conductance. We also found additional spermine binding sites in TRPC4. We evaluated channel activity with electrophysiological recordings and revalidated structural significance based on Cryo-EM structure, which was resolved recently. We found that there is no correlation between magnitude of inhibitory action of spermine and magnitude of maximum current of the channel. In intracellular region, TRPC4 attracts spermine at channel periphery by reducing access resistance, and acidic residues contribute to blocking action of intracellular spermine; channel periphery, E649; cytosolic space, D629, D649, and E687.
Amino Acids ; Binding Sites ; Calcium ; Cytosol ; Glutamic Acid ; Myocytes, Smooth Muscle ; Permeability ; Polyamines ; Receptors, Muscarinic ; Spermine ; Transient Receptor Potential Channels

Polyamines (putrescine, spermidine, and spermine) are essential polycations that play important roles in various physiological and pathophysiological processes in mammalian cells. The study was to investigate their role in cardioprotection against ischemia/reperfusion (I/R) injury and the underlying mechanism. Isolated hearts from male Sprague-Dawley rats were Langendorff-perfused and cardiac I/R was achieved by 30 min of global ischemia followed by 120 min of reperfusion. Different concentrations of polyamines (0.1, 1, 10, and 15 μmol/L of putrescine, spermidine, and spermine), cyclosporin A (0.2 μmol/L), or atractyloside (20 μmol/L) were given 10 min before the onset of reperfusion. The hemodynamics were monitored; the lactate dehydrogenase (LDH) levels in the coronary effluent were measured spectrophotometrically; infarct size was determined by the 2,3,5-triphenyltetrazolium chloride staining method; and mitochondrial permeability transition pore (MPTP) opening was determined spectrophotometrically by the Ca-induced swelling of isolated cardiac mitochondria. The results showed that compared to I/R alone, 0.1 and 1 μmol/L polyamines treatment improved heart function, reduced LDH release, decreased infarct size, and these effects were inhibited by atractyloside (MPTP activator). In isolated mitochondria from normal rats, 0.1 and 1 μmol/L polyamines treatment inhibited MPTP opening. However, 10 and 15 μmol/L polyamines treatment had the opposite effects, and these effects were inhibited by cyclosporin A (MPTP inhibitor). Our findings showed that polyamines may have either protective or damaging effects on hearts suffering from I/R by inhibiting or activating MPTP opening.
Animals ; Cyclosporine ; pharmacology ; Male ; Mitochondria, Heart ; physiology ; Mitochondrial Membrane Transport Proteins ; physiology ; Myocardial Reperfusion Injury ; physiopathology ; Polyamines ; metabolism ; Rats ; Rats, Sprague-Dawley

Astragalus membranaceus (Radix Astragali, RA) and Atractylodes macrocephala (Rhizoma Atractylodis Macrocephalae, RAM) are often used to treat gastrointestinal diseases. In the present study, we determined the effects of polysaccharides extracts from these two herbs on IEC-6 cell migration and explored the potential underlying mechanisms. A migration model with IEC-6 cells was induced using a single-edged razor blade along the diameter of cell layers in six-well polystyrene plates. The cells were grown in control media or media containing spermidine (5 μmol·L, SPD), alpha-difluoromethylornithine (2.5 mmol·L, DFMO), 4-Aminopyridine (40 μmol·L, 4-AP), the polysaccharide extracts of RA or RAM (50, 100, or 200 mg·L), DFMO plus SPD, or DFMO plus polysaccharide extracts of RA or RAM for 12 or 24 h. Next, cytosolic free Ca ([Ca]) was measured using laser confocal microscopy, and cellular polyamine content was quantified with HPLC. Kv1.1 mRNA expression was assessed using RT-qPCR and Kv1.1 and RhoA protein expressions were measured with Western blotting analysis. A cell migration assay was carried out using Image-Pro Plus software. In addition, GC-MS was introduced to analyze the monosaccharide composition of both polysaccharide extracts. The resutls showed that treatment with polysaccharide extracts of RA or RAM significantly increased cellular polyamine content, elevated [Ca] and accelerated migration of IEC-6 cells, compared with the controls (P < 0.01). Polysaccharide extracts not only reversed the inhibitory effects of DFMO on cellular polyamine content and [Ca], but also restored IEC-6 cell migration to control level (P < 0.01 or < 0.05). Kv1.1 mRNA and protein expressions were increased (P < 0.05) after polysaccharide extract treatment in polyamine-deficient IEC-6 cells and RhoA protein expression was increased. Molar ratios of D-ribose, D-arabinose, L-rhamnose, D-mannose, D-glucose, and D-galactose was 1.0 : 14.1 : 0.3 : 19.9 : 181.3 : 6.3 in RA and 1.0 : 4.3 : 0.1 : 5.7 : 2.8 : 2.2 in RAM. In conclusion, treatment with RA and RAM polysaccharide extracts stimulated migration of intestinal epithelial cells via a polyamine-Kv1.1 channel activated signaling pathway, which facilitated intestinal injury healing.
Animals ; Astragalus propinquus ; chemistry ; Atractylodes ; chemistry ; Cell Line ; Cell Movement ; drug effects ; Drugs, Chinese Herbal ; chemistry ; isolation & purification ; pharmacology ; Epithelial Cells ; cytology ; drug effects ; metabolism ; Intestines ; cytology ; drug effects ; Kv1.1 Potassium Channel ; genetics ; metabolism ; Polyamines ; metabolism ; Polysaccharides ; chemistry ; isolation & purification ; pharmacology ; Rats ; Rhizome ; chemistry ; Signal Transduction ; drug effects ; rhoA GTP-Binding Protein ; metabolism

The effect of surface charges on the cellular uptake rate and drug release profile of tetrandrine-loaded poly(lactic-co-glycolic acid) (PLGA) nanoparticles (TPNs) was studied. Stabilizer-free nanoprecipitation method was used in this study for the synthesis of TPNs. A typical layer-by-layer approach was applied for multi-coating particles' surface with use of poly(styrene sulfonate) sodium salt (PSS) as anionic layer and poly(allylamine hydrochloride) (PAH) as cationic layer. The modified TPNs were characterized by different physicochemical techniques such as Zeta sizer, scanning electron microscopy and transmission electron microscopy. The drug loading efficiency, release profile and cellular uptake rate were evaluated by high performance liquid chromatography and confocal laser scanning microscopy, respectively. The resultant PSS/PAH/PSS/PAH/TPNs (4 layers) exhibited spherical-shaped morphology with the average size of 160.3±5.165 nm and zeta potential of-57.8 mV. The encapsulation efficiency and drug loading efficiency were 57.88% and 1.73%, respectively. Multi-layer coating of polymeric materials with different charges on particles' surface could dramatically influence the drug release profile of TPNs (4 layers vs. 3 layers). In addition, variable layers of surface coating could also greatly affect the cellular uptake rate of TPNs in A549 cells within 8 h. Overall, by coating particles' surface with those different charged polymers, precise control of drug release as well as cellular uptake rate can be achieved simultaneously. Thus, this approach provides a new strategy for controllable drug delivery.
Antineoplastic Agents, Phytogenic ; administration & dosage ; chemistry ; Benzylisoquinolines ; administration & dosage ; chemistry ; Cell Line, Tumor ; Drug Liberation ; Humans ; Lactic Acid ; chemistry ; Nanoparticles ; adverse effects ; chemistry ; metabolism ; Polyamines ; chemistry ; Polyglycolic Acid ; chemistry ; Polystyrenes ; chemistry ; Static Electricity

In this study, the buffering capacity of amphiphilic pH-sensitivity copolymer poly(2-ethyl-2-oxazoline)-cholesteryl methyl carbonate (PEOZ-CHMC) was evaluated. The ammonium sulfate gradient method was used to prepare doxorubicin hydrochloride (DOX x HCl)-loaded liposomes (DOX-L), and then the post-insertion method was used to prepare PEOZ-CHMC and polyethylene glycol-distearoyl phosphatidyl ethanolamine (PEG-DSPE) modified DOX x HCl-loaded liposomes (PEOZ-DOX-L and PEG-DOX-L). The physico-chemical properties, in vitro drugs release behavior, cellular toxicity and intracellular delivery of liposomes were evaluated, separately. The results showed that PEOZ-CHMC has a satisfactory buffering capacity. The sephadex G-50 column centrifugation method and dynamic light scattering were used to determine the encapsulation efficiency (EE) and particle size of liposomes. The EE and particle size of DOX-L were (97.3 ± 1.4) % and 120 nm, respectively, and the addition of PEOZ-CHMC or PEG-DSPE had no influence on EE and particle size. The zeta potentials of three kinds of liposomes were negative. The release behavior of various DOX liposomes in vitro was investigated by dialysis method. In phosphate buffer solution (PBS) at pH 7.4, DOX x HCl was released from PEOZ-DOX-L in a sustained manner. While in PBS at pH 5.0, the release rate of DOX x HCl from PEOZ-DOX-L increased significantly, which suggested DOX x HCl was released from PEOZ-DOX-L in a pH-dependent manner. The intracellular delivery of liposomes was investigated by confocal laser scanning microscopy (CLSM). The CLSM images indicated that PEOZ-DOX-L showed efficient intracellular trafficking including endosomal escape and release DOX x HCl into nucleus, as well as the DOX-L and PEG-DOX-L had no this effect. The cytotoxicity of liposomes against MCF-7 cells was detected by using MTT assay. The results showed that antiproliferative effects of PEOZ-DOX-L enhanced with pH value decreased, whereas DOX-L and PEG-DOX-L did not have any significant difference in inhibitions at different pH conditions. Therefore, the problems of the inhibition of cellular uptake of liposomes and the failed endosomal escape of pH-sensitive liposomes by PEG chain can be overcome by the pH-sensitive liposomes constructed by PEOZ-CHMC.
Cell Nucleus ; Doxorubicin ; analogs & derivatives ; chemistry ; Endosomes ; Formates ; chemistry ; Humans ; Liposomes ; chemistry ; MCF-7 Cells ; Microscopy, Confocal ; Particle Size ; Phosphatidylethanolamines ; Polyamines ; chemistry ; Polyethylene Glycols ; chemistry

Polyamines, putrescine, spermidine and spermine, are ubiquitous in living cells and are essential for eukaryotic cell growth. These polycations interact with negatively charged molecules such as DNA, RNA, acidic proteins and phospholipids and modulate various cellular functions including macromolecular synthesis. Dysregulation of the polyamine pathway leads to pathological conditions including cancer, inflammation, stroke, renal failure and diabetes. Increase in polyamines and polyamine synthesis enzymes is often associated with tumor growth, and urinary and plasma contents of polyamines and their metabolites have been investigated as diagnostic markers for cancers. Of these, diacetylated derivatives of spermidine and spermine are elevated in the urine of cancer patients and present potential markers for early detection. Enhanced catabolism of cellular polyamines by polyamine oxidases (PAO), spermine oxidase (SMO) or acetylpolyamine oxidase (AcPAO), increases cellular oxidative stress and generates hydrogen peroxide and a reactive toxic metabolite, acrolein, which covalently incorporates into lysine residues of cellular proteins. Levels of protein-conjuagated acrolein (PC-Acro) and polyamine oxidizing enzymes were increased in the locus of brain infarction and in plasma in a mouse model of stroke and also in the plasma of stroke patients. When the combined measurements of PC-Acro, interleukin 6 (IL-6), and C-reactive protein (CRP) were evaluated, even silent brain infarction (SBI) was detected with high sensitivity and specificity. Considering that there are no reliable biochemical markers for early stage of stroke, PC-Acro and PAOs present promising markers. Thus the polyamine metabolites in plasma or urine provide useful tools in early diagnosis of cancer and stroke.
Acrolein ; Animals ; Biomarkers ; Brain Infarction ; C-Reactive Protein ; Diacetyl ; DNA ; Early Detection of Cancer ; Eukaryotic Cells ; Humans* ; Hydrogen Peroxide ; Inflammation ; Interleukin-6 ; Lysine ; Metabolism ; Mice ; Oxidative Stress ; Oxidoreductases ; Phospholipids ; Plasma ; Polyamines* ; Putrescine ; Renal Insufficiency ; RNA ; Sensitivity and Specificity ; Spermidine ; Spermine ; Stroke

We studied the interaction between proteins and polystyrene-polyacrylic acid (PS-PAA) spherical polyelectrolyte brushes with different polyacrylic acid (PAA) chain lengths, including the physical adsorption and chemical adsorption in PBS buffer. Results showed that the amount of bovine serum albumin (BSA) physically adsorbed on PS-PAA spherical polyelectrolyte brushes decreased to a minimum of 33 microg/mg whereas the amount of streptavidin (SA) chemically adsorbed increased with the increase of chain length and carboxyl quantity. The biotin binding capacity of streptavidin chemically adsorbed on PS-PAA spherical polyelectrolyte brushes was roughly evaluated via enzyme competitive inhibition.
Acrylic Resins ; chemistry ; Adsorption ; Biosensing Techniques ; Electrochemical Techniques ; methods ; Electrolytes ; chemistry ; Polyamines ; Polymers ; chemistry ; Polystyrenes ; chemistry ; Proteins ; chemistry ; Serum Albumin, Bovine ; chemistry ; Surface Properties

A series of quinoline-polyamine conjugates (8a-8n) were designed, synthesized and evaluated as inhibitors of cholinesterases (ChEs). Some of these compounds had potent ChEs inhibitory activity with IC50 values at micromolar range. Compound 8n exhibited the strongest inhibition on acetylcholinesterase (AChE) with an IC50 value of 8.78 micromol x L(-1), and compound 8i showed the most potent inhibition on butyrylcholinesterase (BChE) with IC50 value of 1.60 micromol x L(-1) which was slightly better than rivastigmine. The structure-activity relationship revealed that the chain length of polyamine and linker played important roles for inhibitory activity. Molecular modeling studies showed that 8i targeted both the catalytic active site (CAS) and the peripheral anionic site (PAS) of cholinesterases.
Acetylcholinesterase ; metabolism ; Butyrylcholinesterase ; metabolism ; Cholinesterase Inhibitors ; chemical synthesis ; chemistry ; pharmacology ; Drug Design ; Inhibitory Concentration 50 ; Polyamines ; chemical synthesis ; chemistry ; pharmacology ; Quinolines ; chemical synthesis ; chemistry ; pharmacology ; Structure-Activity Relationship

INTRODUCTIONSevelamer hydrochloride (Renagel) is frequently used as a second-line phosphate binder in patients on renal replacement therapy. Many studies have shown that sevelamer can improve vascular calcification, serum uric acid and low-density lipoprotein (LDL) cholesterol levels. The main objectives of this study were to assess the efficacy of sevelamer against calcium-based phosphate binders, as well as its tolerability and side-effect profile.

METHODSThis was a retrospective study that included all patients on renal replacement therapy (between 2008 and 2011) who had previously received calcium-based binders for ≥ 6 months and were subsequently switched to sevelamer. Data collected from the patients' medical records included demographics, as well as renal parameters three months prior to sevelamer treatment, and at three and six months post treatment. The study excluded patients on multiple, concomitant phosphate binders or with functioning renal transplants, and those who were noncompliant or had inadequate follow-up blood investigations.

RESULTSA total of 39 patients were included in the study. No major side effects were reported by any of the patients. There were improvements in calcium, phosphate, uric acid and LDL cholesterol levels at three and six months post-sevelamer treatment.

CONCLUSIONWe found sevelamer to be superior to calcium-based phosphate binders in reducing serum calcium, phosphate, uric acid and LDL cholesterol levels in our patient population with advanced renal bone disease. Sevelamer also appears to be well tolerated with no significant side effects.

Adult ; Bone Diseases ; complications ; Chelating Agents ; therapeutic use ; Female ; Humans ; Hypercalcemia ; drug therapy ; Hyperphosphatemia ; drug therapy ; Kidney Failure, Chronic ; drug therapy ; Male ; Middle Aged ; Phosphates ; chemistry ; Polyamines ; therapeutic use ; Renal Replacement Therapy ; methods ; Retrospective Studies ; Sevelamer ; Treatment Outcome ; Uric Acid ; blood

This study is to examine the effects of NNIspm-mediated cellular senescence of HepG2 cells and elucidate its potential molecular mechanism. Cellular senescence was detected with senescence-associated beta-galactosidase staining. Cell cycle distribution, intracellular fluorescence intensity and accumulation of intracellular reactive oxygen species (ROS) were detected by high content screening (HCS). Protein expression was detected by Western blotting. Polyamines content was analyzed by high performance liquid chromatography (HPLC). The results demonstrated that NNIspm significantly induced HepG2 cells senescence. This effect was due to the decrease of intracellular polyamines, the arrest at G0/G1 phase and an increase of ROS level. The molecular senescence marker p21 increased significantly after NNIspm treatment. In contrast, the protein expressions of Cyclin E and CDK2 were obvious down-regulation. The results indicated that cellular senescence induced by NNIspm was one of its antitumor mechanisms.
Antineoplastic Agents ; metabolism ; pharmacology ; Cellular Senescence ; drug effects ; Cyclin E ; metabolism ; Cyclin-Dependent Kinase 2 ; metabolism ; Cyclin-Dependent Kinase Inhibitor p21 ; metabolism ; G1 Phase ; Hep G2 Cells ; Humans ; Oncogene Proteins ; metabolism ; Polyamines ; metabolism ; pharmacology ; Reactive Oxygen Species ; metabolism