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A novel epididymal quiescence factor inhibits sperm motility by modulating NOS activity and intracellular NO-cGMP pathway
No full textMature and potentially motile spermatozoa stored in cauda epididymis in an inactive state for approximately 30 days; however, during ejaculation they regain motility. To
understand the actual molecular mechanism of the sperm quiescence during caudal stay, a proteinaceous quiescence factor (QF) has been purified from caprine epididymal
plasma to apparent homogeneity. In the present study complete purification, detailed characterization as well as mechanistic pathway of QF has been described. QF is
purified to 215-fold with 45% activity recovery. It is a 59 kDa monomeric protein with isoelectric point 5.8 and optimally active at pH 7.5. Circular dichroism spectroscopy
and atomic force microscopy study confirm its α-helical secondary structure and globular tertiary conformation. QF is a thermo-stable protein as higher temperature
does not alter its helical structure. N-terminal amino acid sequencing and MALDI analysis of QF did not find 100% similarity with any available protein of the database,
proved its novelty. QF at 2 μMdose inhibits sperm progressive forward motility within 10 min. This motility inhibitory activity of QF is mediated by reducing NOS enzyme
activity and subsequently decreasing the intracellular NO and cGMP concentration. It does not modulate intracellular Ca++ and cAMP concentration. QF has no adverse effect on DNA integrity and morphology of spermatozoa. Motility inhibitory action of QF is reversible. Thus, the role of QF in maintaining energy saving quiescence state of mature cauda spermatozoa and its reactive nitrogen species reducing activity may lead to a new direction for storage of spermatozoa and idiopathic male infertility
Understanding The Role Of Growth factors And Their Receptors In Regulating The Epithelial To Mesenchymal Transition And Invasion Of Ovarian Cancer Cells.
No full textOvarian cancer is the third most leading type of cancer among women in India. The major drawback of ovarian cancer is its detection at an advanced stage, whence the tumor has already metastasized (stage IIIc). This stage involves the spread of the cancer cells across the lymph nodes into the upper abdomen and the treatment regimen of these patients involves surgical removal of the tumor followed by systemic chemo-and radio-therapy. Thwarting the metastatic behavior along with early detection are thus the major challenges in combatting this aggressive type of cancer.
The metastatic behavior of cancers depends on the invasive/migratory properties of the tumor cells. During metastasis the tumor cells enter into the bloodstream and invade to a secondary site. The process of Epithelial-Mesenchymal transition (EMT) governs the invasive/metastatic behavior of different cancer types including ovarian cancer. The spindle shaped morphology of the cells attained by virtue of rearrangement of actin-cytoskeleton during EMT promotes the invasive behavior of tumor cells. The process of EMT is governed by a plethora of growth-factor signaling cascades. Enhanced growth factor functioning by virtue of upregulation of the growth factors or their receptors is one of prominent features of cancer cells. In fact, differential splicing of the receptors also contributes to the amplification of growth-factor mediated signaling. Apart from the well documented transcriptional regulation of EMT, alternative splicing has been implicated in the modulation of this trans-differentiation process. EMT is accompanied by alterations in the repertoire of splice isoforms which in turn modulate each of cancer hallmarks. Different growth factor signaling pathways and transcription factors have been involved in the regulation of these splicing changes which ultimately facilitate cancer metastasis.
We have tried to address these issues in this thesis by designing proper model systems and performing numerous experiments to shed light into the mechanisms governing ovarian cancer metastasis. This thesis is comprised of three chapters: Chapter I deals with the interaction among two growth factor (FGF and VEGF) families and their contribution towards ovarian cancer metastasis. In this study, we have explored the mechanism governing the augmentation of VEGF and its main receptor in ovarian cancer cells and its impact in modulating the invasive behavior of the cells. Chapter II elucidates mechanism governing the splice isoform switching of Fibroblast growth factor receptors and the roles of these splice variants in regulating EMT/invasion of ovarian cancer cells. This study depicts that a growth factor (FGF2) modulates the isoform switching of its own receptor (FGFR2) to promote autocrine signaling which enhances the metastatic potential of ovarian cancer cells. Chapter III concerns a co-receptor molecule, CD44, which is differentially spliced in ovarian cancer cells. Precisely, this study depicts growth factor (TGFβ1/Activin-A) induced EMT involves the splice isoform switching of CD44. This splicing switch in turn, modulated the metastatic properties of ovarian cancer cells. Therefore, we have explored some of the undeciphered mechanisms which promote the metastatic properties of ovarian cancer. Since enhanced invasion/metastasis render lethality to ovarian cancer, our work and future works in this direction might be useful in developing therapies to combat this aggressive gynaecological disease
Perils of Genome Assembly: Data types and sequencing platform defines optimal genome assembly in prokaryotes and eukaryotes
No full textThe Molecular Mechanisms of Lipid-Induced Insulin Resistance and Its Amelioration by the Novel Anti-Diabetic Agents
No full textUnderstanding parkinsonism using cellular and animal models: Effect of a natural antioxidant and hypercholesterolemia
No full textHBV quasispecies composition in Lamivudine-failed chronic hepatitis B patients and its influence on virological response to Tenofovir-based rescue therapy
Full text linkThe present study sought to evaluate the structure of HBV quasispecies in Lamivudine (LMV)-failed chronic hepatitis B (CHB) patients and its impact in defining the subsequent virological responses to Tenofovir (TDF)-based rescue-therapy. By analyzing HBV clones encompassing reverse transcriptase (RT) and surface (S) region from LMV-failed and treatment-naïve CHB patients, we identified 5 classical and 12 novel substitutions in HBV/RT and 9 substitutions in immune-epitopes of HBV/S that were significantly associated with LMV failure. In silico analysis showed spatial proximity of some of the newly-identified, mutated RT residues to the RT catalytic centre while most S-substitutions caused alteration in epitope hydrophobicity. TDF administration resulted in virological response in 60% of LMV-failed patients at 24-week but non-response in 40% of patients even after 48-weeks. Significantly high frequencies of 6 S-substitutions and one novel RT-substitution, rtH124N with 6.5-fold-reduced susceptibility to TDF in vitro, were noted at baseline in TDF non-responders than responders. Follow-up studies depicted greater evolutionary drift of HBV quasispecies and significant decline in frequencies of 3 RT and 6 S-substitutions in responder-subgroup after 24-week TDF-therapy while most variants persisted in non-responders. Thus, we identified the HBV-RT/S variants that could potentially predict unfavorable response to LMV/TDF-therapy and impede immune-mediated viral clearance
Biodegradable Neuro-Compatible Peptide Hydrogel Promotes Neurite Outgrowth, Shows Significant Neuroprotection, and Delivers Anti-Alzheimer Drug
No full textA novel neuro-compatible peptide-based hydrogel has been designed and developed, which contains microtubule stabilizing and neuroprotective short peptide. This hydrogel shows strong three-dimensional cross-linked
fibrillary networks, which can capture water molecules.
Interestingly, this hydrogel serves as excellent biocompatible soft material for 2D and 3D (neurosphere) neuron cell culture and provides stability of key cytoskeleton filaments such as microtubule and actin. Remarkably, it was observed that this hydrogel slowly enzymatically degrades and releases neuroprotective peptide, which promotes neurite outgrowth of neuron cell
as well as exhibits excellent neuroprotection against anti-NGF-induced toxicity in neuron cells. Further, it can encapsulate antiAlzheimer and anticancer hydrophobic drug curcumin, releases slowly, and inhibits significantly the growth of a 3D spheroid of neuron cancer cells. Thus, this novel neuroprotective hydrogel can be used for both neuronal cell transplantation for repairing brain damage as well as a delivery vehicle for neuroprotective agents, anti-Alzheimer, and anticancer molecules
Ruthenium(II)-catalyzed intermolecular synthesis of 2-arylindolines through C–H activation/ oxidative cyclization cascade
No full textHerein, we report a ruthenium-catalyzed 1,2-carboamination through C–H activation for the synthesis of 2-arylindolines from readily available, inexpensive, protected anilines and vinyl arenes. In earlier reports, indoline synthesis through C–H activation was
demonstrated using sterically or electronically biased olefins suppressing b-hydride elimination. However, in the present protocol a ruthenium(II)-catalyzed indoline synthesis via interrupted Heck-type manifold with unbiased styrenes is demonstrated. Mechanistically, the
reaction proceeds through pyrimidine directed electrophilic ortho metalation, alkene insertion, amine coordination, and reductive elimination to construct the indoline nucleu
Determining The Structural And Functional Importance Of Bio-Molecular Complexes Of Microbial Proteins Using Network Biology, Molecular Modeling And Docking Approaches.
No full textMicrobial pathogenesis involves a complex interplay between differential expression of pathogenic virulence and host’s immune system. Pathogenic virulence is characterized by their degree of pathogenicity and capacity to invade host’s defence mechanisms. A dynamic
relationship exists between host and pathogen since each modifies the biological functions of the other, and the outcome is mainly dependable on pathogenic virulence and the relative degree of resistance or susceptibility of the host. Pathogens undertake various strategies to
infect the host. Upon foreign challenges host evolves immune response in order to initiate the
defence mechanism. The progression of the infection mechanism involved in alteration of
host’s immune response which initiates the molecular interaction between host-pathogen
interactions. The host-pathogen interactions are mainly involved in recognising the proteinprotein
interactions (PPI). These PPI perhaps play important role in the disease progression. Identification of such PPI may help in understanding the role of host molecules in pathogenic infection. Insight into such molecular pathogenicity may widen a new aspect in determining
the pharmacological intervention of newly identified targets.
Pathogens are single celled, responsible for causing a wide array of diseases and they include agents like protozoa, bacteria, virus, prion, fungus etc. Leishmania is an obligatory intracellular protozoan parasite. It is responsible for causing leishmaniasis. Types of
leishmaniasis depends upon the types of leishmanial species involved into it. This may range
from cutaneous, mucocutaneous to another most destructive form, visceral leishmaniasis.
Visceral leishmaniasis is mostly prevailed in the tropical region. It is mostly caused by
Leishmania donovani. Leishmaniasis is considered as one of the most neglected tropical disease, which is prevalent in the Indian subcontinent. Although pentavalent antimonials and amphotericin B were the mainstream therapy for past 70 years, however 60% of leishmanial patient currently does not respond to the existing available drugs. Hence, it become essential
for us to identify novel target molecules and develop respective new drugs. In order to reach this goal, new target molecules should be evaluated by
understanding the complex biological interaction between Leishmania and their host molecules. It is important to understand the complex protein-protein interactions in the pathogenesis of this disease. This in turn can be achieved by the study of host-Leishmania
protein-protein interaction network. These networks will aid in identifying proteins and their respective interactions can be used as new targets for drugs and vaccines development. More specifically, understanding this host-pathogen protein-protein interaction network will open a new perspective in analysing how a pathogen exploits a host molecule to setup the infection process.
Plasmodium falciparum is responsible to cause one of the most life-threatening disease, malaria. Drug resistance is becoming one of the prime bottleneck in managing this
disease, which accounts for millions of deaths annually. Henceforth, to understand its pathogenesis, identification and characterization of novel proteins which can be considered as drug targets are considered as a fundamental approach. Plasmodium genome constitutes
family of DNA-binding proteins. These proteins are involved in regulation of its gene expression for virulence. One of the major architectural DNA-binding proteins are Alba family proteins which organizes and regulates the genome of both euryarchea (having
histone) as well as crenarchea (having no histone) and is regulated by acetylation and deacetylation. Genome analysis of Plasmodium falciparum revealed that it encodes a putative DNA–RNA-binding protein, PfAlba3, showing the sequence and structural homology with
other Alba family proteins. Currently, not much information is known regarding PfAlba3 to
elucidate its role in P. falciparum. Therefore, it is important to identify and understand the
structural features of PfAlba3 protein which regulates the cellular growth and development of
malarial parasite and may be considered one of the possible targets of this global disease.
Several Gram-negative bacteria uses a complex protein delivery mechanism known as Type III secretion system (T3SS). It injects the toxins or effectors into the host cells to establish its virulence. Pseudomonas aeruginosa, a gram-negative pathogen, use T3SS translocator proteins, and associates with their common chaperones PcrH to rupture the cholesterol rich host cell membranes and inject toxic effector molecules into the host cell to
establish its virulence. However, due to unavailability of crystal structure of the translocator protein, PopB, the exact mode of this chaperone-translocator interaction is deficient. To understand the functional insights into the T3SS translocation mechanism, it is crucial to
study the structural aspects of the individual proteins along with the binding mechanism of the full length PopB-PcrH complex. This will help in deciphering the structure-function relationships among T3SS translocator proteins and also encourage the design of PopB
protein inhibitors that can combat the pathogenesis into host cell. Another ultimate hitchhiker pathogens are viruses which invades the host immune cells by attaching the virions and hijack the cellular internal machinery to replicate within it.This causes the rupture of the cell and newly-formed virus particles are free to infect other
cells. Among these a genus of double-stranded RNA viruses in the family of Reoviridae is rotavirus. Rotavirus is the single most common etiological pathogen. It is responsible for causing severe diarrhea in infants and resulting death of over half a million infants a year.
However, till date there is no effective anti-retroviral drug have been successfully implemented for treatment of rotavirus infection. Therefore, an approach can be undertaken in identification and characterization of anti-retroviral drug for rapid recovery. An adenosine
analogue, Cordycepin (3’-deoxyadenosine), has been reported to provide protection against HIV infection which further modulate the cell proliferation and platelet aggregation.Moreover, it has potent inhibitory role in inhibiting rotavirus infection. Therefore, a study was undertaken to understand the structural mechanism of binding of cordycepin onto its
preferential domain of the molecular target which will affect the cellular signaling. Thus, to understand the complexity of pathogenesis and etiology of host-pathogen
relationship in terms of network and structural biology, I have undertaken the following objectives as my studies for dissertation:
1. Understanding the structural and functional dynamics of host-Leishmania protein-protein
interaction network.
2. Identification and characterization of novel protein from P. falciparum which is
ubiquitously expressed in all the erythrocytic stages of P. falciparum
3. Analyzing the probable mode of binding of the major T3SS PopB from Pseudomonas
aeruginosa with its chaperone PcrH.
4. Identifying the efficacy of an anti rotaviral drug in providing the protection against
rotavirus