Biology subjects

Kumar, P.

Publications and source records attributed to Kumar, P..

266 records · Page 15Linked to original sources

bioRxiv2018

Galectin-1 promotes the invasion of bladder cancer urothelia through their matrix milieu

The progression of carcinoma of the urinary bladder involves migration of cancer epithelia through their surrounding tissue matrix microenvironment. This was experimentally confirmed when a gender- and grade-diverse set of bladder cancer cell lines were cultured in pathomimetic three-dimensional laminin-rich environments. The high-grade cells, particularly female, formed multicellular invasive morphologies in 3D. In comparison, low- and intermediate-grade counterparts showed growth-restricted phenotypes. A proteomic approach combining mass spectrometry and bioinformatics analysis identified the estrogen-driven lactose-binding lectin Galectin-1 (GAL-1) as a putative candidate that could drive this invasion. Expression of LGALS1, the gene encoding GAL-1 showed an association with tumor grade progression in bladder cell lines. Immunohisto- and cyto-chemical experiments suggested greater extracellular levels of GAL-1 in 3D cultures of high-grade bladder cells and cancer tissues. High levels of GAL-1 associated with increased proliferation- and adhesion- of bladder cancer cells when grown on laminin-rich matrices. Pharmacological inhibition and Gal-1 knockdown in high-grade female cells decreased their adhesion to, and viability on, laminin-rich substrata. Higher GAL-1 also correlated with reduced E-cadherin and increased N-cadherin levels in consonance with a mesenchymal-like phenotype that we observed in 3D culture. The inhibition of GAL-1 reversed the stellate invasive phenotype to a more growth-restricted one in high-grade cells embedded within both basement-membrane-like and stromal collagenous matrix scaffolds. Finally, inhibition of GAL-1 specifically altered cell surface sialic acids, suggesting the mechanism by which the levels of GAL-1 may underlie the aggression and poor prognosis of invasive bladder cancer, especially in women.

cancer biology↗

bioRxiv2018

A second generation IL-2 receptor-targeted diphtheria fusion toxin exhibits anti-tumor activity and synergy with anti-PD-1 in melanoma

Denileukin diftitox (DAB1-389-IL-2, Ontak(R)) is a diphtheria toxin-based fusion protein that depletes CD25-positive cells including regulatory T cells (Tregs) and was approved for the treatment of persistent or recurrent cutaneous T cell lymphoma. However, the clinical use of denileukin diftitox was limited by vascular leak toxicity and production issues related to drug aggregation and purity. We found that a single amino acid substitution (V6A) in a motif associated with vascular leak induction yields a fully active, second-generation biologic, s-DAB1-386-IL-2(V6A), which elicits 50-fold less HUVEC monolayer permeation and is 3.7-fold less lethal to mice by LD50 analysis than s-DAB1-386-IL-2 Additionally, to overcome aggregation problems, we developed a novel production method for the fusion toxin using Corynebacterium diphtheriae that secretes fully-folded, biologically active, monomeric s-DAB1-386-IL-2 into the culture medium. Using the poorly immunogenic mouse B16F10 melanoma model, we initiated treatment 7 days after tumor challenge and observed that, while both s-DAB1-386-IL-2(V6A) and s-DAB1-386-IL-2 are inhibitors of tumor growth, the capacity to treat with higher doses of s-DAB1-386-IL-2(V6A) could provide a superior activity window. In a sequential dual therapy study in tumors that have progressed for 10 days both s-DAB1-386-IL-2(V6A) and s-DAB1-386-IL-2 given prior to checkpoint inhibition with anti-PD-1 antibodies inhibited tumor growth, while either drug given as monotherapy had less effect. s-DAB1-386-IL-2(V6A), a fully monomeric protein with reduced vascular leak, is a second-generation diphtheria toxin-based fusion protein with promise as a cancer immunotherapeutic both alone and in conjunction with PD-1 blockade.\n\nSignificance StatementRegulatory T cells (Tregs) infiltrate tumors in various cancers and promote an immunosuppressive microenvironment that hinders anti-tumor immunity. Denileukin diftitox, a diphtheria toxin-based fusion protein that depletes Tregs, was approved for the treatment of T cell malignancies, but its clinical use was limited due to the presence of protein aggregates and toxicity associated with vascular leakage. Here we report the production of a second generation IL-2 receptor-targeted, fully-folded, monomeric diphtheria fusion toxin, and a V6A mutant variant which showed reduced vascular leak in vitro and reduced lethality in mice. In a mouse model of melanoma, we found significant decrease in tumor growth associated with reduction in Tregs when the protein was tested as monotherapy or in combination with checkpoint blockade.

cancer biology↗

bioRxiv2018

Assessment Of Genetic Structure Of The Endangered Forest Species Boswellia Serrata Roxb. Population In Central India

Boswellia serrata Roxb., a commercially important species for its pulp and pharmaceutical properties was sampled from three locations representing its natural distribution in central India for genetic characterization through 56 RAPD + 42 ISSR loci. The wood fiber dimensions measured for morphometric characterization confirmed 11.36% of the variation in the length and 8.75% of the variation in the width indicating its fitness for local adaptation. Bayesian and non-Bayesian approach based diversity measures resulted moderate within population gene diversity (0.26{+/-}0.17), Shannons information index (0.40{+/-}0.22) and panmictic heterozygosity (0.28{+/-}0.01). A high estimate for genetic differentiation measures i.e. GST (0.31), GST-B (0.33{+/-}0.02) and {theta}-II (0.45) led to the distinct clusters of the sampled genotypes representing their regional variability due to limited gene flow and total absence of natural regeneration. We report the first investigation of the species for its molecular characterization emphasizing the urgent need for the genetic improvement program for the In-situ/Ex-situ conservation and sustainable commercialization.

plant biology↗

bioRxiv2018

Effects of Temperatures and High Pressures on the Growth and Survivability of Methanogens and Stable Carbon Isotope Fractionation: Implications for Deep Subsurface Life on Mars

In order to examine the potential survivability of life in the Martian deep subsurface, we have investigated the effects of temperature (45{degrees}C, 55{degrees}C, and 65{degrees}C) and pressure (1 atm, 400 atm, 800 atm, and 1200 atm) on the growth, carbon isotopic data, and morphology of chemolithoautotrophic anaerobic methanogenic archaea, Methanothermobacter wolfeii. The growth and survivability of this methanogen were determined by measuring the methane concentration in headspace gas samples after the cells were returned to their conventional growth conditions. Interestingly, this methanogen survived at all the temperatures and pressures tested. M. wolfeii demonstrated the highest methane concentration following exposure to pressure of 800 atm and a temperature of 65{degrees}C. We found that the stable carbon isotopic fractionation of methane, {delta}13C(CH4), was slightly more enriched in 12C at 1 atm and 55{degrees}C than the carbon isotopic data obtained in other temperature and pressure conditions. A comparison of the images of the cells before and after the exposure to different temperatures and pressures did not show any obvious alteration in the morphology of M. wolfeii. The research reported here suggests that at least one methanogen, M. wolfeii, may be able to survive under hypothetical Martian subsurface conditions with respect to temperature and pressure.

microbiology↗

bioRxiv2018

FITC Conjugated Polycaprolactone-Glycol-Chitosan Nanoparticles Containing The Longwave Emitting Fluorophore IR 820 For In-Vitro Tracking Of Hyperthermia-Induced Cell Death

Cancer theranostic agent IR 820 loses its bioimaging ability once therapy is initiated. At the end of therapy, it becomes difficult to track the cancer cells. To address this, FITC conjugated Polycaprolactone glycol chitosan IR 820 nanoparticles (FITC-PCLGC-IR NPs) has been synthesized for in vitro tracking of hyperthemia induced cell death. Two approaches, namely ex situ and in situ have been pursued FITC conjugation to PCLGC-IR NPs. Further comparisons were made to FITC encapsulated PCLGC-IR NPs in terms of biocompatibility, cellular uptake, photothermal mediated cell death and imaging with respect to laser treatment. We have shown that an 808 nm diode laser treatment did not affect the imaging ability of these NPs whereas cancer. Time scanned fluorescence shows the excellent photostability of this formulation for a maximum of 5 min. The detailed studies of these approaches summarize that FITC conjugation to PCLGC-IR nanoparticles is an effective nano-theranostic solution for image-guided photothermal therapy.

bioengineering↗

bioRxiv2018

Myosin Heavy Chain-embryonic is a crucial regulator of skeletal muscle development and differentiation.

Myosin heavy chains (MyHCs) are contractile proteins that are part of the thick filaments of the functional unit of the skeletal muscle, the sarcomere. In addition to MyHCs that are part of the adult muscle contractile network, two MyHCs - MyHC-embryonic and -perinatal are expressed during muscle development and are only transiently expressed in the adult during regeneration. The functions performed by these MyHCs has been a long-standing question and using a targeted mouse allele, we have characterized the role of MyHC-embryonic. Analysis of loss-of-function mice reveals that lack of MyHC-embryonic leads to mis-regulation of other MyHCs, alterations in fiber size, fiber number and fiber type at neonatal stages. We also find that loss of MyHC-embryonic leads to mis-regulation of genes involved in muscle differentiation. A broad theme from these studies is that loss of MyHC-embryonic has distinct effects on different muscles, possibly reflecting the unique fiber type composition of different muscles. Most significantly, our results indicate that MyHC-embryonic is required during embryonic and fetal myogenesis to regulate myogenic progenitor and myoblast differentiation in a non-cell autonomous manner via Mitogen Activated Protein Kinase (MAPKinase) and Fibroblast Growth Factor (FGF) signaling. Thus, our results signify that MyHC-embryonic is a key regulator of myogenic differentiation during embryonic, fetal and neonatal myogenesis.

developmental biology↗

bioRxiv2018

Evolution of an intratumoral ecology susceptible to successive treatment in breast cancer xenografts

The processes by which tumors evolve are essential to the efficacy of treatment, but quantitative understanding of intratumoral dynamics has been limited. Although intratumoral heterogeneity is common, quantification of evolution is difficult from clinical samples because treatment replicates cannot be performed and because matched serial samples are infrequently available. To circumvent these problems we derived and assayed large sets of human triple-negative breast cancer xenografts and cell cultures from two patients, including 86 xenografts from cyclophosphamide, doxorubicin, cisplatin, docetaxel, or vehicle treatment cohorts as well as 45 related cell cultures. We assayed these samples via exome-seq and/or high-resolution droplet digital PCR, allowing us to distinguish complex therapy-induced selection and drift processes among endogenous cancer subclones with cellularity uncertainty <3%. For one patient, we discovered two predominant subclones that were granularly intermixed in all 48 co-derived xenograft samples. These two subclones exhibited differential chemotherapy sensitivity -- when xenografts were treated with cisplatin for 3 weeks, the post-treatment volume change was proportional to the post-treatment ratio of subclones on a xenograft-to-xenograft basis. A subsequent cohort in which xenografts were treated with cisplatin, allowed a drug holiday, then treated a second time continued to exhibit this proportionality. In contrast, xenografts from other treatment cohorts, spatially dissected xenograft fragments, and cell cultures evolved unsystematically but with substantial population bottlenecks. These results show that ecologies susceptible to successive retreatment can arise spontaneously in breast cancer in spite of a background of irregular subclonal bottlenecks, and our work provides to our knowledge the first quantification of the population genetics of such a system. Intriguingly, in such an ecology the ratio of common subclones is predictive of the state of treatment susceptibility, suggesting that this ratio can be measured to optimize dynamic treatment protocols in patients.\n\nAUTHOR SUMMARYAn overarching challenge of cancer is that patients develop resistance to treatment -- an essentially evolutionary process. However, there is currently very little understanding of how tumor evolution can be exploited to improve treatment. One reason for this is that usually only 1-2 samples can be obtained per patient, so cancer evolutionary processes are still poorly understood. To solve this problem, we created many dozens of copies of the tumors from two breast cancer patients using xenografting and cell culture methods. We then compared the evolution in these tumor copies in response to different treatments, including four of the most common breast cancer chemotherapies. These studies present the most exhaustive comparisons of treatment-induced evolution that have yet been performed for individual cancer patients. Unexpectedly, high-resolution sequencing of these samples revealed a special dynamically treatable ecology in one tumor, in which tumor growth during platinum therapy was determined by the ecological balance of two tumor cell populations. Our work shows that ecologies that can be targeted by dynamic treatment strategies arise spontaneously in breast cancers. Population heterogeneity is common within cancers, and our work suggests how tracking of intratumoral evolution can be used to optimize treatment.

cancer biology↗

bioRxiv2018

A computational method to aid the design and analysis of single cell RNA-seq experiments for cell type identification

BackgroundThe advent of single cell RNA sequencing (scRNA-seq) enabled researchers to study transcriptomic activity within individual cells and identify inherent cell types in the sample. Although numerous computational tools have been developed to analyze single cell transcriptomes, there are no published studies and analytical packages available to guide experimental design and to devise suitable analysis procedure for cell type identification.\n\nResultsWe have developed an empirical methodology to address this important gap in single cell experimental design and analysis into an easy-to-use tool called SCEED (Single Cell Empirical Experimental Design and analysis). With SCEED, user can choose a variety of combinations of tools for analysis, conduct performance analysis of analytical procedures and choose the best procedure, and estimate sample size (number of cells to be profiled) required for a given analytical procedure at varying levels of cell type rarity and other experimental parameters. Using SCEED, we examined 3 single cell algorithms using 48 simulated single cell datasets that were generated for varying number of cell types and their proportions, number of genes expressed per cell, number of marker genes and their fold change, and number of single cells successfully profiled in the experiment.\n\nConclusionsBased on our study, we found that when marker genes are expressed at fold change of 4 or more than the rest of the genes, either Seurat or Simlr algorithm can be used to analyze single cell dataset for any number of single cells isolated (minimum 1000 single cells were tested). However, when marker genes are expected to be only up to fC 2 upregulated, choice of the single cell algorithm is dependent on the number of single cells isolated and proportion of rare cell type to be identified. In conclusion, our work allows the assessment of various single cell methods and also aids in examining the single cell experimental design.

bioinformatics↗

bioRxiv2018

Euchromatic histone methyltransferases regulate peripheral heterochromatin tethering via histone and non-histone protein methylations

Euchromatic histone methyltransferases (EHMTs), members of the KMT1 family, methylate histone and non-histone proteins. Here we uncover a novel role for EHMTs in regulating heterochromatin anchorage to the nuclear periphery (NP) via non-histone (LaminB1) methylations. We show that EHMTs methylates and stabilizes LaminB1 (LMNB1), which associates with the H3K9me2-marked peripheral heterochromatin. Loss of LMNB1 methylation or EHMTs abrogates the heterochromatin anchorage from the NP. We further demonstrate that the loss of EHMTs induces many hallmarks of aging including global reduction of H3K27methyl marks along with altered nuclear-morphology. Consistent with this, we observed a gradual depletion of EHMTs, which correlates with loss of methylated LMNB1 and peripheral heterochromatin in aging human fibroblasts. Restoration of EHMT expression reverts peripheral heterochromatin defect in aged cells. Collectively our work elucidates a new mechanism by which EHMTs regulate heterochromatin domain organization and reveals their impact on fundamental changes associated with the intrinsic aging process.

genetics↗

bioRxiv2017

Induction of autophagy by trehalose limits opportunistic mycobacterial infections in HIV-infected macrophages

Opportunistic bacterial infections amongst HIV-infected individuals pose serious health challenge. While immediate control of bacterial pathogens is typically attributed to innate defense mechanisms, whether HIV-mediated modulation of innate mechanisms like autophagy promote opportunistic infections, remains obscure. Using U1.1 and U937 macrophages, we show, HIV activation or infection inhibits autophagy and helps survival of pathogenic Mycobacterium tuberculosis and non-pathogenic non-tuberculous mycobacterial strains (NTMs) like Mycobacterium avium complex and Mycobacterium fortuitum. HIV achieves this by blocking xenophagy flux, which could be reversed by the autophagy inducer trehalose that kills intracellular Mtb and NTMs. We found trehalose acts as a PI (3,5) P2 agonist and activates TRPML1 to induce autophagy. Remarkably, trehalose treatment significantly reduced p24 levels in PBMCs infected with clinical HIV strains and in PBMCs derived from treatment-naive HIV patients. Taken together, our study highlights the immense potential of autophagy modulators in the therapeutic intervention of HIV and associated opportunistic infection.

immunology↗

bioRxiv2017

Global Gene Repression By Dicer-Independent tRNA Fragments

tRNA derived RNA fragments (tRFs) is an emerging group of small RNAs as abundant as miRNAs, and yet their roles are not well understood. Here, we focus on endogenous tRFs (18-22 bases) derived from 3 end of human mature tRNAs (tRF-3) and their functions in gene repression. tRF-3 levels increase upon parental tRNA over-expression or tRNA induction by c-Myc oncogene activation. Elevated tRF-3 levels lead to repression of target genes with a sequence complementary to the tRF-3 in the 3 UTR. The tRF-3-mediated repression is Dicer-independent, Argonaute-dependent and the targets are recognized by 5 seed sequence rules similar to miRNAs. Furthermore, tRF-3s associate with GW proteins in P-bodies. RNA-seq identifies the endogenous target genes of tRF-3s that are specifically repressed upon tRF-3 induction. Overall, our analysis shows Dicer-independent tRF-3s, generated upon tRNA upregulation such as c-Myc overexpression, regulate gene expression globally through Argounate via seed sequence matches.

molecular biology↗

bioRxiv2017

Altered Expression Of A Unique Set Of Genes Reveals Complex Etiology Of Schizophrenia

PurposeThe etiology of schizophrenia is extensively debated, and multiple factors have been contended to be involved. A panoramic view of the contributing factors in a genome-wide study can be an effective strategy to provide a comprehensive understanding of its causality.\n\nMaterials and MethodsGSE53987 dataset downloaded from GEO-database, which comprised mRNA expression data of post-mortem brain tissue across three regions from control and age-matched subjects of schizophrenia (N= Hippocampus (HIP): C-15, T-18, Prefrontal cortex (PFC): C-15, T-19, Associative striatum (STR): C-18, T-18). Bio-conductor-affy-package used to compute mRNA expression, and further t-test applied to investigate differential gene expression. The analysis of the derived genes performed using PANTHER Classification System and NCBI database.\n\nResultsA set of 40 genes showed significantly altered (p<0.01) expression across all three brain regions. The analyses unraveled genes implicated in biological processes and events, and molecular pathways relating basic neuronal functions.\n\nConclusionsThe deviant expression of genes maintaining basic cell machinery explains compromised neuronal processing in SCZ.\n\nAbbreviationsSchizophrenia (SCZ), Hippocampus (HIP), Associative striatum (STR), Prefrontal cortex (PFC)

neuroscience↗

bioRxiv2017

Feature Engineering Coupled Machine Learning Algorithms For Epileptic Seizure Forecasting From Intracranial EEGs

Epilepsy is one of the major neurological disorders affecting nearly 1 percentage of the global population. The major blunt is born by under developed and developing countries due to expensive treatment of epileptic conditions. Further, the lack of proper forecasting methods for an occurrence of epileptic seizures in epileptic-drug resistant patients or patients not amenable for surgery affects their psychological behaviour and restricts their daily activities. The forecasting is usually performed by human experts that leave a wide gap for human-bias and human error. Therefore, in the current work, we have evaluated the efficiency of several machine learning algorithms to automatically identify the preictal patterns corresponding to epileptic seizures from intracranial EEG signals. The robustness of the machine learning algorithms were tested after the data set was pre-processed using carefully chosen feature engineering strategies viz. denoised Fourier transforms as well as cross-correlation across electrodes in time and frequency domain. Extensive experimentations were carried out to determine the best combination of feature engineering techniques and machine learning algorithms. The best combination of feature engineering techniques and machine learning algorithm resulted in 0.7685 AUC (Area under the Receiver Operating Characteristic curve) on the random test samples. The suggested approach was fairly good at prediction of epilepsy in random samples and therefore, it can be used in epileptic seizure forecasting in patients where medication/surgery is ineffective. Eventually, our strategy reveals a robust method for brain disorders forecasting from EEGs.

bioengineering↗

bioRxiv2017

Feature Extraction Through Wavelet Decomposition For Automatic Detection Of Landmarks On Cephalogram Images

Manual cephalogram marking has long way from marking on tracing sheet to availability of commercial software's for cephalometric analysis. With the effort involved in manual marking and time consumption, it becomes imperative for modern science to envisage algorithms which could automatically locate landmarks on the cephalogram images and perform various analysis. In this work, we herby propose a wavelet transform based feature extraction algorithm for detection of landmark on cephalogram images. 15 landmarks were detected on the images using wavelet transform and all landmarks were detected within the acceptable accuracy limits. This algorithm may have a promising approach in detection of further anatomical landmarks automatically and analysis and thus may help orthodontic practioners in better and faster treatment planning.

bioengineering↗