FT-Raman and QM/MM study of the interaction between histamine and DNA

Photomodulating Carbon Dots for Spatiotemporal Suppression of Alzheimer's β-Amyloid Aggregation

Extracellular deposition of β-amyloid (Aβ) peptide aggregates is a major characteristic of Alzheimer's disease (AD) brain. Because Aβ peptide aggregates aggravate neuropathy and cognitive impairment for AD patients, numerous efforts have been devoted to suppressing Aβ self-assembly as a prospective AD treatment option. Here, we report Aβ-targeting, red-light-responsive carbon dots (CDs), and their therapeutic functions as a light-powered nanomodulator to spatiotemporally suppress toxic Aβ aggregation both in vitro and in vivo. Our aptamer-functionalized carbon dots (Apta@CDs) showed strong targeting ability toward Aβ₄₂ species. Moreover, red LED irradiation induced Apta@CDs to irreversibly denature Aβ peptides, impeding the formation of β-sheet-rich Aβ aggregates and attenuating Aβ-associated cytotoxicity. Consequently, Apta@CDs-mediated photomodualtion modality achieved effective suppression of Aβ aggregation in vivo, which significantly reduced the Aβ burden at the targeted sites in the brain of 5xFAD mice by ∼40% and ∼25% according to imaging and ELISA analyses, respectively. Our work demonstrates the therapeutic potential of photomodulating CDs for light-driven suppression against Aβ self-assembly and related neurotoxicity.

Capillary electrophoresis-based approaches for the study of affinity interactions combined with various sensitive and nontraditional detection techniques

Nearly all processes in living organisms are controlled and regulated by the synergy of many biomolecule interactions involving proteins, peptides, nucleic acids, nucleotides, saccharides, and small molecular weight ligands. There is growing interest in understanding them, not only for the purposes of interactomics as an essential part of system biology, but also in their further elucidation in disease pathology, diagnostics, and treatment. The necessity of detailed investigation of these interactions leads to the requirement of laboratory methods characterized by high efficiency and sensitivity. As a result, many instrumental approaches differing in their fundamental principles have been developed, including those based on capillary electrophoresis. Although capillary electrophoresis offers numerous advantages for such studies, it still has one serious limitation, its poor concentration sensitivity with the most commonly used detection method-ultraviolet-visible spectrometry. However, coupling capillary electrophoresis with a more sensitive detector fulfils the above-mentioned requirement. In this review, capillary electrophoresis combined with fluorescence, mass spectrometry, and several nontraditional detection techniques in affinity interaction studies are summarized and discussed, together with the possibility of conducting these measurements in microchip format.

Organelle-Targeting Gold Nanorods for Macromolecular Profiling of Subcellular Organelles and Enhanced Cancer Cell Killing

Subcellular organelles, for example, nucleus, mitochondria, and lysosome, are the vital organelles with responsibilities that maintain cell operation and metabolism. Owing to their roles in energy production and programmed cell death, these organelles have become prime therapeutic targets in different diseases and states. In this study, biocompatible, organelle-targeting nanoprobes were developed by modifying gold nanorods (AuNRs) with specific targeting peptides. These nanoprobes were employed to directly profile subcellular biomolecules and vital organelles by surface-enhanced Raman scattering (SERS) spectroscopy. Macromolecular spectral profiles of subcellular organelles were achieved and compared. Further, these organelle-targeting AuNRs were used for the photothermal treatment of cancer cells (HepG2, HeLa, and MCF-7 cell lines). The cell viability assays show that the nucleus- and mitochondria-targeting AuNRs provide higher photothermal efficiencies under an 808 nm laser relative to the lysosome-targeting ones. This study makes critical insights into the spectral profiles of subcellular organelles and also inspires people in the development of high-efficacy cancer therapeutic strategies by subcellular organelle-targeting drugs.

Plasmon-enhanced Raman spectroscopic metrics for in situ quantitative and dynamic assays of cell apoptosis and necrosis

Plasmon-enhanced Raman spectroscopic metrics were developed for in situ quantitative and dynamic assays of viable, apoptotic and necrotic cells.

Apoptosis and necrosis are distinct cell death processes related to many cellular pathways. In situ, quantitatively and dynamically monitoring such processes may provide vitally important information for cell studies. However, such a method still remains elusive, even though current immunochemical methodologies have developed extremely valuable tools. Herein, we demonstrate Raman spectroscopic metrics for validating and quantifying apoptotic and necrotic cells based on their distinct molecular vibrational fingerprints. It not only allows us to quantify apoptotic and necrotic cell populations in situ in adherent cell samples, but also to be capable of continuously monitoring the dynamical processes of apoptosis and necrosis at the same time in one sample. This method provides comparable results with the “gold standard” of flow cytometry, moreover, with several incomparable advantages. Our work offers a powerful new tool for cell apoptosis and necrosis assays and is expected to become a benchmark technology in biological and medical studies.

Conformational study of neutral histamine monomer and their vibrational spectra

Molecular modeling and potential energy scanning of histamine molecule, which is an important neurotransmitter, with respect to the dihedral angle of methylamine side chain have done which prefer three different conformers of histamine monomer. We have calculated molecular structures and vibrational spectra with IR and Raman intensities of these conformers using Density Functional Theory (DFT) with the exchange functional B3LYP incorporated with the basis set 6-31++G(d,p) and Hartree-Fock (HF) with the same basis set. We have also employed normal coordinate analysis (NCA) to scale the theoretical frequencies and to calculate potential energy distributions (PEDs) for the conspicuous assignments. Normal modes assignments of some of the vibrational frequencies of all the three conformers are in good agreement with the earlier reported experimental frequencies of histamine whereas others have modified. The standard deviations between the theoretical and experimental frequencies fall in the region 13-20cm(-1) for the three conformers. NBO analyses of histamine conformers were also performed. The net charge transfers from ethylamine side chain to the imidazole ring. The intensive interactions between bonding and anti-bonding orbitals are found in imidazole ring. The HOMO-LUMO energy gap is nearly 5.50eV.

Multilayered thin films from poly(amido amine)s and DNA

Dip-coated multilayered thin films of poly(amido amine)s (PAAs) and DNA have been developed to provide surfaces with cell-transfecting capabilities. Three types of PAAs, differing in side chain functional groups, were synthesized and characterized for their properties in forming multilayered structures with ultrasonicated calf thymus DNA (CTDNA) as model DNA. All three polymers display a multilayer build-up in linear profiles as demonstrated by UV spectroscopy. More highly charged side chains were found to provide the lowest deposition of DNA. Surface profiles of the obtained films were investigated by atomic force microscopy (AFM) and static water contact angle measurements to reveal complete surface coverage after at least four layer pair depositions, where alternating patterns of surface profiles were observed depending on whether the cationic polymer or the anionic DNA layer was on top. The stability of the formed surfaces was investigated in vitro under physiological and reductive conditions. Owing to the presence of disulfide bonds in the PAA main chain, the films were readily degraded in the presence of 1mM of DTT in vitro. Under non-reductive physiological conditions, two of the thicker films underwent thermodynamic rearrangement, which resulted in release of approximately half of the incorporated material within 1h, which was caused by the physiological salt concentration. Further, this unpacking phenomenon proved useful in transfecting COS-7 cells seeded on top of these multilayers containing functional plasmid DNA encoding for green fluorescence protein (GFP). Two out of the three different multilayers facilitated good COS-7 cell attachment, proliferation, and transfection in vitro within 2d ays of culture. Fluorescence staining further revealed the presence of DNA-containing released film material among cultured cells. The present work demonstrates the possibility of coating surfaces with thin films that are conveniently adjustable in thickness and amount of active agent to provide cell-transfecting functionality. In this manner transfection can be achieved by simply culturing cells on a multilayer-coated surface in their optimal culture condition (in the presence of serum) and without the need of removing the transfection agent to avoid cytotoxicity.

Observing real-time molecular event dynamics of apoptosis in living cancer cells using nuclear-targeted plasmonically enhanced Raman nanoprobes

Apoptosis is a biological process that plays important roles in embryogenesis, aging, and various diseases. During the process of apoptosis, cells undergo a series of morphological and molecular events such as blebbing, cell shrinkage, proteolysis, and nuclear DNA fragmentation. Investigating these events on a molecular level is crucial for gaining a more complete understanding of the intricate mechanism of apoptosis; however, the simultaneous direct observation of morphological and molecular events in real-time on a single living cell scale still remains a challenge. Herein, we directly monitored morphological and molecular events during cellular apoptosis in real-time after the treatment of an apoptosis-inducing agent, by utilizing our previously described plasmonically enhanced Rayleigh/Raman spectroscopic technique. Spectroscopic analysis of the DNA/protein composition around the cell nucleus revealed the occurrence and dynamics of three apoptotic molecular events: protein denaturation, proteolysis, and DNA fragmentation. The molecular event dynamics were used to create a temporal profile of apoptotic events in single cells. It is found that the sequence of events occurring in the apoptotic process induced by hydrogen peroxide addition is protein denaturation through disulfide bond breakage as well as DNA fragmentation, followed in time by protein unraveling with hydrophobic amino acid exposure, and finally protein degradation. These results demonstrate the potential of using this time-dependent plasmonically enhanced vibrational imaging technique to study the detailed mechanism of other apoptosis molecular pathways induced by different agents (e.g., anticancer drugs). A note is given in the conclusion discussing the expected large difference between the SERS spectrum of biological molecules in solution and that observed in live cells which are enhanced by the plasmonic field of the aggregated nanoparticles.

Effect of Aegle marmelos leaf extract on N-methyl N-nitrosourea-induced hepatocarcinogensis in Balb/c mice

CONTEXT AND OBJECTIVE

Tobacco smoke and nitrostable foods containing N-methyl N-nitrosourea (MNU) are among the primary causes of liver cancer. To substantiate the beneficial claims ascribed to Aegle marmelos (L.) Corrêa (Rutaceae), the hepatoprotective potential of its leaf extract was studied using an MNU-induced hepatocarcinogenesis model in Balb/c mice.

MATERIALS AND METHODS

After dose selection, 40 mice were randomly assigned to 4 groups: I (control), II (intraperitoneally (i.p.) primed with 50 mg/kg MNU), III (100 mg/kg A. marmelos hydroalcoholic extract (HEAM) i.p.) and IV (MNU + HEAM, i.p.). Inflammatory (IL-1β, IL-6), anti-inflammatory (IL-4) cytokine expression, apoptosis (Bcl-2) and tumor-related (p53, c-jun) genes were assessed at mRNA level. HEAM effects on hematological parameters were examined.

RESULTS AND DISCUSSION

HEAM treatment decreased IL-1β, IL-6, Bcl-2 and c-jun respectively expressions by 90, 25, 53 and 30%, respectively. p53 and IL-4 expression was up-regulated by 1.5- and 2-fold. MNU decreased hemoglobin concentration (25%), lymphocyte count (42%) and increased leukocyte (100%), platelet (4-fold), neutrophil (43%), monocyte (10-fold) and eosinophil (10-fold) counts in Group II mice while HEAM modulated the same parameters by -7%, -21%, +24%, +3-fold, +12%, +3-fold and +4-fold, respectively, in MNU-induced mice compared to control. HEAM protective effect was confirmed by Raman spectroscopy where the MNU-induced peak at 1252 cm(-1) was normalized. DNA fragmentation data suggest apoptosis as one of the protective mechanisms of HEAM.

CONCLUSION

The hepatoprotective, anti-carcinogenic and immunomodulatory effects of A. marmelos extract indicate potential beneficial effects in cancer therapy.

N-methyl N-nitroso Urea induced altered DNA structure initiate hepatocarcinogenesis

The status of inflammatory cytokines IL-1β, IL-6, the anti-apoptotic gene Bcl2 and key transcription factor NFκB in hepatic milieu of N-methyl N-nitroso Urea (MNU) primed Balb/c mice was assessed using RT-PCR and Western blot. Haematoxyline & Eosin (H&E) based histology was performed to evaluate the morphological changes in the cancerous liver cells in respect to control. Laser spectroscopy was used to study the alteration in DNA structure. 40 week MNU treatment induced increased expressions of inflammatory cytokines (IL-1β, IL-6) of Bcl-2 at mRNA level and NFκB and IL-1β at protein level. Alteration in hepatocytes was clearly demonstrated in H&E stained liver sections compared to control. MNU primed liver DNA samples revealed an interference of MNU in nucleic acid bases and structure, reflected by a peak shift at 1456 cm(-1) and shoulder formation at 1357 cm(-1) compared to control DNA samples. This study emphasizes that MNU, a harmful industrial and environmental pollutant, potentially activates inflammatory cytokines (IL-1β, IL-6) in hepatic cells with increased expression of NFκB which might be responsible for hepatocarcinogenesis in Balb/c mice. The outcome sets the basis for further studies on the mitigating effects of dietary biofactors on MNU.

Surface-enhanced Raman study of the interactions between tripodal cationic polyamines and polynucleotides

Raman and surface-enhanced Raman spectra of new DNA/RNA-binding compounds consisting of three imidazole (Im) and three pyridine (Py) rings connected by tripodal polyaminomethylene linkages were obtained by the near-infrared excitation at 1064 nm. Study of interactions of Im and Py polyamines with single-stranded RNA polynucleotides (poly A, poly G, poly C, poly U), double-stranded DNA polynucleotides (poly dAdT-poly dAdT, poly dGdC-poly dGdC) and calf thymus DNA (ct-DNA) by surface-enhanced Raman spectroscopy (SERS) reveals unambiguous enhancement of the Raman scattering from the small molecules as well as appearance of new bands in spectra associated mainly with nucleobases. The SERS experiments point toward comparable interactions of Im and Py polyamines with single-stranded purine and pyrimidine polynucleotides. Furthermore, SERS experiments with double stranded polynucleotides reveal the base-pair dependent selectivity of Im and Py, whereby interactions within both, major and minor groove are indicated for poly dAdT-poly dAdT, at variance to preferred binding of Im and Py to only major groove of poly dGdC-poly dGdC. SERS spectra of Im and Py with ct-DNA imply that protonated amino groups of these compounds preferentially interact with N7 atoms (adenine, guanine) while nitrogen in aromatic rings of polyamines might be attracted to C6-NH(2) (adenine), all sites being located at the major groove of the DNA helix. Wavenumber downshift of the imidazole (Im) and pyridine (Py) ring vibrations supports aromatic stacking interactions of imidazole and pyridine aromatic moieties with DNA base-pairs.

Signal transduction and adaptive regulation through bacterial two-component systems: the Escherichia coli AtoSC paradigm

Adaptive signal transduction within microbial cells involves a multi-faceted regulated phosphotransfer mechanism that comprises structural rearrangements of sensor histidine kinases upon ligand-binding and phosphorylation-induced conformational changes in response regulators of versatile two-component systems (TCS), arisen early in bacterial evolution. In Escherichia coli, cross-talk between the AtoS histidine kinase and the AtoC response regulator, forming the AtoSC TCS, through His --> Asp phosphotransfer, activates AtoC directly to induce atoDAEB operon expression, thus modulating diverse fundamental cellular processes such as short-chain fatty acid catabolism, poly-(R)-3-hydroxybutyrate biosynthesis and chemotaxis. Among the inducers hitherto identified, acetoacetate is the classical activator. The AtoSC TCS functional modulation by polyamines, histamine and Ca(2+), as well as the role of AtoC as transcriptional regulator, add new promising perspectives in the physiological significance and potential pharmacological exploitation of this TCS in cell proliferation, bacteria-host interactions, chemotaxis, and adaptation.

Development of an expression macroarray for amine metabolism-related genes

Cationic amino acids are the precursors of biogenic amines, histamine from histidine, and putrescine, spermidine and spermine from arginine/ornithine (and methionine), as well as nitric oxide. These amines play important biological roles in inter- and intracellular signaling mechanisms related to inflammation, cell proliferation and neurotransmission. Biochemical and epidemiological relationships between arginine-derived products and histamine have been reported to play important roles in physiopathological problems. In this communication, we describe the construction of an expression macroarray containing more than 30 human probes for most of the key proteins involved in biogenic amines metabolisms, as well as other inflammation- and proliferation-related probes. The array has been validated on human mast HMC-1 cells. On this model, we have got further support for an inverse correlation between polyamine and histamine synthesis previously observed on murine basophilic models. These tools should also be helpful to understand the amine roles in many other inflammatory and neoplastic pathologies.