Biology subjects

De, D.

Publications and source records attributed to De, D..

3 recordsLinked to original sources

bioRxiv2021

High throughput screening of a new fluorescent G-quadruplex ligand having telomerase inhibitory activity in human A549 cells

Genome-wide analysis showed that putative G-quadruplex DNA structures are prevalent in the human genome. The presence of G-quadruplex structure in the telomere and promoter region of certain oncogenes inspired people to use G-quadruplex ligand as anti-cancer agents. G-quadruplex structures, stabilized by ligand at telomere are resolved by telomerase making the cancer cells resistant to G-quadruplex ligand. So, identification of a new G-quadruplex ligand having anti-telomerase activity would be a promising strategy for cancer therapy as about 85% of human cancers are telomerase positive. A set of the drug-like compounds were screened from the ZINC database randomly and 2284 ligands were chosen following Lipinskis rule of five that were docked with five different G-quadruplex DNA sequences in idock. We screened 43 potential G-quadruplex binders using Z-score as a normalization scoring function. The compound (ZINC ID-05220992) gave the best score (average idock = -10.17 kcal/mol, average normalized idock = -3.42). We performed G4 FID assay, CD analysis to understand its binding with three different G-quadruplex DNA sequences, and checked its anti-telomerase activity in A549 cells using TRAP assay. We observed that this compound had an intrinsic fluorescence, capability to stain live cells with a blue fluorescence, and a specific affinity to only 22AG out of three different G-quadruplex DNA sequences under study. It showed cytotoxicity, good permeability to live cells, and a significant reduction of telomerase activity in human A549 cells at a very low dose. So, this compound has strong potential to be an anti-cancer drug. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=151 SRC="FIGDIR/small/470216v1_ufig1.gif" ALT="Figure 1"> View larger version (41K): org.highwire.dtl.DTLVardef@116cce1org.highwire.dtl.DTLVardef@1e500c1org.highwire.dtl.DTLVardef@194a0b3org.highwire.dtl.DTLVardef@c258fe_HPS_FORMAT_FIGEXP M_FIG C_FIG HighlightsO_LIA set of compounds were screened randomly by a High throughput method and Lipinskis rule of five from ZINC database to identify potential G4-binders. C_LIO_LIThe compound (ZINC ID-05220992) was screened after docking with five G-quadruplex DNA C_LIO_LIIt binds G-quadruplex DNA 22AG as detected by TO displacement and CD spectroscopy. C_LIO_LIIt inhibits telomerase activity in A549 cells and also cytotoxic to this cell. C_LIO_LIIt penetrates live A549 cell in culture and stains it with blue fluorescence C_LI

molecular biology↗

bioRxiv2021

Rheb-mTOR Activation Rescues Amyloid Beta-Induced Cognitive Impairment and Memory Function by Restoring miR-146 Activity in Glial Cells

Deposition of amyloid beta plaques in adult rat or human brain is associated with increased production of proinflammatory cytokines by associated glial cells that are responsible for degeneration of the diseased tissue. The expression of these cytokines is usually under check and is controlled at post-transcriptional level via several microRNAs. Computational analysis of gene expression profiles of cortical regions of Alzheimers disease patients brain suggests ineffective target cytokine mRNA suppression by existing microRNPs in diseased brain. Exploring the mechanism of amyloid beta induced cytokine expression, we have identified how the inactivation of the repressive miR-146 microRNPs causes increased production of cytokines in amyloid beta exposed glial cells. In exploration of the cause of miRNP inactivation, we have noted amyloid beta oligomer induced sequestration of mTORC1 complex to early endosomes that results in decreased Ago2 phosphorylation, limited Ago2-miRNA uncoupling and retarded Ago2-cytokine mRNA interaction in rat astrocyte cells. Interestingly, constitutive activation of mTORC1 by Rheb activator restricts proinflammatory cytokine production by reactivating miR-146 microRNPs in amyloid beta exposed glial cells to rescue the disease phenotype in the in vivo rat model of Alzheimers disease.

neuroscience↗

bioRxiv2020

Amyloid Beta Oligomers Prevents Lysosomal Targeting of miRNP to Stop Its Recycling and Target Cytokine Repression in Glial Cells

mRNAs encoding inflammatory cytokines are targeted by miRNAs and remain repressed in neuroglial cells. On exposure to amyloid beta 1-42 oligomers, glial cells start expressing proinflammatory cytokines although there has been increase in repressive miRNAs levels as well. Exploring the mechanism of this potential immunity of target cytokine mRNAs against repressive miRNAs in amyloid beta exposed glial cells, we have identified differential compartmentalization of repressive miRNAs in glial cells to explain this aberrant miRNA function. While the target mRNAs were found to be associated with polysomes attached to endoplasmic reticulum, the miRNPs found to be present predominantly with endosomes that failed to recycle to endoplasmic reticulum attached polysomes to repress mRNA targets in treated cells. Amyloid beta oligomers, by masking the Rab7 proteins on endosomal surface, affects Rab7 interaction with Rab Interacting Lysosomal Protein (RILP) on lysosomes to restrict endosomal maturation and its lysosomal targeting. This causes retarded miRNP targeting to lysosomes and recycling. Similar defects in miRNP retrieval has been observed in endosome maturation defective cells depleted for RILP or treated with Bafilomycin. RNA processing body localization of the miRNPs was also noted in treated cells that happens as a consequence of enhanced endosomal retention of miRNPs. Interestingly, depletion of P-body partly rescues the miRNA function in glial cells exposed to amyloid beta and restricts the excess cytokine expression there. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=71 SRC="FIGDIR/small/424324v1_ufig1.gif" ALT="Figure 1"> View larger version (17K): org.highwire.dtl.DTLVardef@1d9453dorg.highwire.dtl.DTLVardef@150a9c4org.highwire.dtl.DTLVardef@b99a1aorg.highwire.dtl.DTLVardef@1342676_HPS_FORMAT_FIGEXP M_FIG C_FIG Key PointsO_LIAmyloid beta exposure causes accumulation of inactive miR-146 miRNP to cause elevated proinflammatory cytokine production in glial cells. C_LIO_LIAmyloid beta masks Rab7-RILP interaction to reduce endosome lysosome interaction. C_LIO_LIAccumulated miRNPs failed to get targeted to lysosomes in amyloid exposed cells due to loss of endosome lysosome interaction C_LIO_LILysosomal compartmentalization of miRNPs is required for its recycling and repression of de novo targets C_LIO_LIAccumulated miRNPs are stored in P-Bodies and depletion of P-Bodies rescues miRNA function in amyloid exposed glial cells. C_LI

cell biology↗