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Polymer-fabricated synthesis of cerium oxide nanoparticles and applications as a green catalyst towards multicomponent transformation with size-dependent activity studies
No full textIn this paper, we have studied the equilibrium unfolding transitions of cytochrome c from Pseudomonas
aeruginosa (cytc551), a small bacterial protein. Similar to eukaryotic cytochrome c, cytc551 folds sequentially,
although significant differences exist in the order of folding units (foldons). There are two regions of cytc551
(N-terminal helix with residue number 3 to 10 and the loop 2 region containing residues 34 to 45), in which no
foldon unit could be assigned. In addition, the helix containing the Cys-X-X-Cys-His motif, adjacent to the
N-terminal helix (residue number 3 to 10), shows unexplained ultra-fast collapse. To obtain further insights, we
have studied cytc551 site-directed mutants using fluorescence correlation spectroscopy (FCS) and molecular
dynamics simulation. We have found out that cytc551 unfolds through the formation of a fluorescently dark
intermediate state and the amplitude of the dark component depends on the position of labeling. We have
utilized this position dependence to propose a shape change model during the unfolding of cytc551. The
present results show that the N-terminal helix remains in a collapsed position even in the completely unfolded
state and this helix may act as a rigid support to guide the folding of its adjacent helix. This rigid support may
be responsible for the ultra-fast collapse of the adjacent helix region, which occurs during the initial events of
folding. The present results also show that the C-terminal end of loop 2 traverses a large distance during
unfolding compared to the N-terminal end, which justifies the observed flexibility of the loop 2 regio
Molecular association of glucose-6- phosphate isomerase and pyruvate kinase M2 with glyceraldehyde-3-phosphate dehydrogenase in cancer cells
Get PDFBackground: For a long time cancer cells are known for increased uptake of glucose and its metabolization through
glycolysis. Glyceraldehyde-3-phosphate dehydrogenase (GAPDH) is a key regulatory enzyme of this pathway and can
produce ATP through oxidative level of phosphorylation. Previously, we reported that GAPDH purified from a variety of malignant tissues, but not from normal tissues, was strongly inactivated by a normal metabolite, methylglyoxal (MG).Molecular mechanism behind MG mediated GAPDH inhibition in cancer cells is not well understood.
Methods: GAPDH was purified from Ehrlich ascites carcinoma (EAC) cells based on its enzymatic activity. GAPDH
associated proteins in EAC cells and 3-methylcholanthrene (3MC) induced mouse tumor tissue were detected by mass spectrometry analysis and immunoprecipitation (IP) experiment, respectively. Interacting domains of GAPDH
and its associated proteins were assessed by in silico molecular docking analysis. Mechanism of MG mediated GAPDH
inactivation in cancer cells was evaluated by measuring enzyme activity, Circular dichroism (CD) spectroscopy, IP and mass spectrometry analyses.
Result: Here, we report that GAPDH is associated with glucose-6-phosphate isomerase (GPI) and pyruvate kinase M2
(PKM2) in Ehrlich ascites carcinoma (EAC) cells and also in 3-methylcholanthrene (3MC) induced mouse tumor tissue.
Molecular docking analyses suggest C-terminal domain preference for the interaction between GAPDH and GPI.
However, both C and N termini of PKM2 might be interacting with the C terminal domain of GAPDH. Expression of both PKM2 and GPI is increased in 3MC induced tumor compared with the normal tissue. In presence of 1 mM MG,association of GAPDH with PKM2 or GPI is not perturbed, but the enzymatic activity of GAPDH is reduced to 26.8 ± 5 % in 3MC induced tumor and 57.8 ± 2.3 % in EAC cells. Treatment of MG to purified GAPDH complex leads to glycation at R399 residue of PKM2 only, and changes the secondary structure of the protein complex.
Conclusion: PKM2 may regulate the enzymatic activity of GAPDH. Increased enzymatic activity of GAPDH in tumor cells may be attributed to its association with PKM2 and GPI. Association of GAPDH with PKM2 and GPI could be a signature for cancer cells. Glycation at R399 of PKM2 and changes in the secondary structure of GAPDH complex could be one of the mechanisms by which GAPDH activity is inhibited in tumor cells by MG
Phosphorylation of Ago2 and Subsequent Inactivation of let-7a RNPSpecific MicroRNAs Control Differentiation of Mammalian Sympathetic Neurons
No full textMicroRNAs (miRNAs) are small regulatory RNAs that regulate gene expression posttranscriptionally by base pairing to the target mRNAs in animal cells. KRas, an oncogene known to be repressed by let-7a miRNAs, is expressed and needed for the differentiation of mammalian sympathetic neurons and PC12 cells. We documented a loss of let-7a activity during this differentiation process without any significant change in the cellular level of let-7a miRNA. However, the level of Ago2, an essential component that is associated with miRNAs to form RNP-specific miRNA (miRNP) complexes, shows an increase with neuronal differentiation.
In this study, differentiation-induced phosphorylation and the subsequent loss of miRNA from Ago2 were noted, and these
accounted for the loss of miRNA activity in differentiating neurons. Neuronal differentiation induces the phosphorylation of mitogen-activated protein kinase p38 and the downstream kinase mitogen- and stress-activated protein kinase 1 (MSK1). This in turn upregulates the phosphorylation of Ago2 and ensures the dissociation of miRNA from Ago2 in neuronal cells. MSK1-mediated
miRNP inactivation is a prerequisite for the differentiation of neuronal cells, where let-7a miRNA gets unloaded from Ago2 to ensure the upregulation of KRas, a target of let-7a. We noted that the inactivation of let-7a is both necessary and sufficient for the differentiation of sympathetic neuron
Cofacial Organic Click Cage to Intercalate Polycyclic Aromatic Hydrocarbons
No full textThe synthesis of a 3-fold symmetric cofacial organic cage (COC) through Cu(I)-catalyzed azide−alkyne cycloaddition is reported. The COC can function as an efficient receptor for carcinogenic polycyclic aromatic hydrocarbons to intercalate them in its intrinsic cavity through donor−acceptor and π···π stacking interactions. The
association constants (Ka) are in the range of 3.7 × 104 to 1.3 × 106 M−1. X-ray diffraction analysis authenticated that the polycyclic aromatic hydrocarbons (PAHs) are
intercalated in the interior of the COC
Molecular study and in-depth transcriptome analysis of Phyllanthus amarus leaves identifying lignans and other secondary metabolites biosynthetic pathway gene/s
No full textHealing with plants of medicinal significance is as old as mankind itself. The awareness of usage of medicinal plants by human beings for the treatment of diverse ailments, is a result of thousands of years of struggles, since, by trial and error, man distinguished between the beneficial and poisonous plants. Ample evidence from various sources - be it written documents, preserved monuments, and even original
plant medicines supporting the connection between man and his search for drugs innature dates from the far past. Be it the Indian Holy Books like the Vedas dating around 5000 B.C., or the Chinese book “Pen T’Sao,” written by Emperor Shen Nung in 2500 B.C. describing 365 drugs derived from various dried parts of medicinal plants - various such historical sources relevant for the study of medicinal plants’ use are present. The oldest written evidence of the use of medicinal plants for preparation of drugs has been found on a Sumerian clay slab from Nagpur, approximately 5000 years old (Kelly, 2009). The Ebers Papyrus written in 1550 B.C. refers to 700 plant species and drugs used for therapy such as pomegranate, castorbean, aloe, senna, garlic, onion, fig, willow, coriander, juniper, common
centaury, etc. Homer's epics - The Iliad and The Odysseys created in 800 B.C. refer to 63 plant species from the Minoan, Mycenaean, and Egyptian Assyrian pharmacotherapy. Herodotus (500 B.C.) referred to castor oil plant, Orpheus to the fragrant hellebore and garlic, and Pythagoras to the sea onion (Scilla maritima), mustard, and cabbage. The works of Hippocrates (459 B.C. - 370 B.C.) contain
about 300 medicinal plants classified by physiological action. Theophrast (371 B.C. - 287 B.C.) gained the epithet of “the father of botany” for his great merits for the
classification and description of medicinal plants. He generated a classification of more than 500 medicinal plants known at the time in his books “De Causis
Plantarium”— Plant Etiology and “De Historia Plantarium”—Plant History. Celsus (25 B.C. - 50 A.D.), the renowned medical writer quoted approximately 250
medicinal plants such as aloe, henbane, flax, poppy, pepper, cinnamon, the star gentian, cardamom, false hellebore, etc. in his work “De re medica”. In ancient
history, the most prominent writer on plant drugs was Dioscorides, “the father of pharmacognosy” who wrote the work “De Materia Medica”. This classical work of
ancient history offers plenty of data on the medicinal plants constituting the basic materia medica until the late Middle Ages and the Renaissance. Pliny the Elder (23A.D. - 79 A.D.), a contemporary of Dioscorides, who travelled throughout Germanyand Spain, wrote about approximately 1000 medicinal plants in his book “Historia naturalis.
PTEN negatively regulates mTORC2 formation and signaling in grade IV glioma via Rictor hyperphosphorylation at Thr1135 and direct the mode of action of an mTORC1/2 inhibitor
Get PDFTo investigate the role of PTEN (phosphatase and tensin homolog) in mammalian target of rapamycin complex 2 (mTORC2)
signaling in glioblastoma multiforme (GBM), we found higher activation of mTORC2 in PTENmu cells, as evidenced by enhanced
phosphorylation of mTOR (Ser2481), AKT (Ser473) and glycogen synthase kinase 3 beta (GSK3β) (Ser9) as compared with PTENwt
cells. In addition, PTENwt cells upon PTEN depletion showed mTORC2 activation. The reduced mTORC2 signaling in PTENwt cells was
related to higher Rictor phosphorylation at Thr1135 residue. Phosphorylation of Rictor at Thr1135 inhibited its association with
mTORC and thus there was a reduction in mTORC2 complex formation. In addition, PTENwt cells expressing mutated Rictor in which
Thr1135 was substituted with alanine, showed enhanced mTORC2 formation and signaling. This enhanced mTORC2 signaling
promoted inactivation of GSK3β. Thus, we established the reciprocal activation of mTORC2 and GSK3β in GBM. To the best of our
knowledge, this is the first report describing role of PTEN in mTORC2 formation by promoting Rictor phosphorylation (Thr1135) in
GBM. Furthermore, the drug sensitivity of mTORC2 was evaluated. A newly identified carbazole alkaloid, mahanine, showed
cytotoxicity in both PTENmu and PTENwt cells. It inhibited both mTORC1/2 and AKT completely in PTENmu cells, whereas it inhibited
only mTORC1 in PTENwt cells. Cytotoxity and AKT-inhibitory activity of the mTORC1/2 inhibitor was increased either by depleting
PTEN or in combination with phosphatidylinositol 3 kinase inhibitors in PTENwt cells. In contrast, depletion of Rictor decreased the
cytotoxicity of the mTORC1/2 inhibitor in PTENmu cells. Thus, PTEN has an important role in mTORC2 formation and also influences
the effectiveness of an mTORC1/2 inhibitor in GBM
Adipose recruitment and activation of plasmacytoid dendritic cells fuel metaflammation
No full textIn obese individuals the visceral adipose tissue (VAT) becomes seat of chronic low grade inflammation (metaflammation). But the mechanistic link between increased adiposity and metaflammation remains largely unclear. We report here that in obese individuals
deregulation of a specific adipokine, chemerin, contributes to innate initiation of metaflammation, by recruiting circulating plasmacytoid dendritic cells (pDCs) into visceral adipose tissue via chemokine-like receptor 1 (CMKLR1). Adipose tissue-derived high
mobility group B1 (HMGB1) protein, activates toll-like receptor 9 (TLR9) in the adiposerecruited
pDCs by transporting extracellular DNA via receptor for advanced glycation endproducts (RAGE) and induces production of type I interferons. Type I interferons in
turn help in proinflammatory polarization of adipose-resident macrophages. Interferon signature gene expression in VAT correlates with both adipose tissue and systemic insulin resistance in obese individuals, represented by ADIPO-IR and HOMA2-IR respectively,
and defines two subgroups with different susceptibility to insulin resistance. Thus our study reveals a hitherto unknown pathway that drives adipose tissue inflammation and consequent insulin resistance in obesity
Studies on the molecular mechanism of mutant p53 mediated chemo-resistance and its related oncogenic gain of functions in human cancer
No full textMore than half of the human cancers harbor TP53 mutation. These are mostly missense mutations that confer both loss-of-function and gain-of-function (GOF) properties to the p53 protein. Besides losing wild type tumor suppressor activities, certain tumor associated p53 missense mutants gain novel oncogenic functions and actively drive tumorigenesis by promoting several cancer-inducing mechanisms. “Gain-of-function” mutant p53 physically interacts with other cellular proteins and can also regulate crucial genes and non coding RNAs by acting as an oncogenic transcription factor. Reports suggest that transcriptional property is one of the crucial mechanisms by which mutant p53 confers its gain-of-function activities. Mutant p53 modulates diverse signaling pathways different from those regulated by the wild type protein and promotes cancer phenotypes including increased cellular proliferation, metastasis, invasion and enhanced chemoresistance. Although several studies over the last decade have identified multiple cellular pathways and molecular mechanisms underlying mutant p53 gain-of-functions, many more still need to be explored to completely unravel the growing complexity of oncogenic mutant p53.
In this study, we investigated the role of GOF mutant p53 in regulating DNA replication, a commonly altered pathway in human cancer. We report that Cdc7-dependent increased replication initiation enables mutant p53 to confer oncogenic phenotypes. We found DNA replication as the most significantly altered pathway by GOF mutant p53 in lung adenocarcinoma patients with significant up-regulation of replication initiation factor CDC7 kinase. We showed that mutant p53 cooperates with Myb transcription factor in vivo and transactivates CDC7 in cancer cells. Chromatin enrichment of pre-initiation complex proteins such as phosphorylated Mcm2 and Cdc45 suggested increased replication initiation in mutant p53 cells. Furthermore, DNA fiber assay confirmed Cdc7-mediated increased origin firing in cells expressing mutant p53. Importantly, Cdc7 inhibition significantly abrogated the anchorage-independent growth and chemoresistance phenotypes of mutant p53 expressing cancer cells. We also found significant correlation between CDC7 overexpression and poor survival of the lung adenocarcinoma patients harboring p53 mutation. Thus, our study suggests Cdc7-dependent altered replication initiation as an essential factor in mutant p53 gain-of-functions. We propose that targeting Cdc7 kinase may be an effective strategy in treating human cancers harboring mutant p5
Reconstitution Of Alzheimer Disease Propagation Pathway Using Aβ Peptide And Its Link With Cancer
No full textAmong the various diseases, Alzheimer’s disease is one of the diseases where aggregation of Aβ42 peptide plays a significant role. But detail understanding of the disease
propagation pathway is unknown. Cancer is another fatal disease and there is an inverse association between cancer and Alzheimer’s disease. But the effect of synthetic Aβ42 peptide on cancer cells has not been discussed yet. Therefore, main objectives of the total work are:
a) Understanding the aggregation of Aβ42 peptide in brain and propagation of Alzheimer’s disease using liposome as artificial cell like system. b) Understanding the link between Alzheimer’s disease and cance
α‑Cyclodextrin Interacts Close to Vinblastine Site of Tubulin and Delivers Curcumin Preferentially to the Tubulin Surface of Cancer Cell
No full textTubulin is the key cytoskeleton component, which plays
a crucial role in eukaryotic cell division. Many anticancer drugs have been developed targeting the tubulin surface. Recently, it has been shown that few polyhydroxy carbohydrates perturb tubulin polymerization.
Cyclodextrin (CD), a polyhydroxy carbohydrate, has been
extensively used as the delivery vehicle for delivery of hydrophobic drugs to the cancer cell. However, interaction of CD with intracellular components has not been addressed before. In this Article, we have shown for the first time that α-CD interacts with tubulin close to the
vinblastine site using molecular docking and Förster resonance energy transfer (FRET) experiment. In addition, we have shown that α-CD binds with intracellular tubulin/microtubule. It delivers a high amount
of curcumin onto the cancer cell, which causes severe disruption of intracellular microtubules. Finally, we have shown that the inclusion complex of α-CD and curcumin (CCC) preferentially enters into the human lung cancer cell (A549) as compared to the normal lung fibroblast cell (WI38), causes apoptotic death, activates tumor suppressor protein (p53) and cyclin-dependent kinase inhibitor 1 (p21), and inhibits 3D spheroid growth of cancer cel