• ASHOK KUMAR

      Articles written in Journal of Biosciences

    • Cross reactivity and enzyme sensitivity of immunoaffinity purified Sm/RNP antigens

      Ashok Kumar Rashid Ali

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      Immunoaffinity purified Sm/RNP antigens from buffalo and goat liver were studied to determine the role of RNA and proteins towards the antigenicity of Sm and RNP antigens. A more direct approach using enzyme-linked immunosorbent assay on nylon beads has been utilized to look into the problem. The effect of enzyme treatment and the role of RNA and protein fractions in influencing antigenicity have been described. RNA seems to be involved in the maintenance of RNP specific polypeptides in suitable conformation so as to keep them in solution. Removal of RNA leads to insolubilization of RNP specific polypeptides. Antibodies to Sm and RNP antigens have been shown to cross react with poly A containing heterogeneous nuclear ribonucleoprotein with no cross reactivity with thymus RNA or DNA.

    • Immune modulation by dendritic-cell-based cancer vaccines

      CHAITANYA KUMAR SAKSHI KOHLI POONAMALLE PARTHASARATHY BAPSY ASHOK KUMAR VAID MINISH JAIN VENKATA SATHYA SURESH ATTILI BANDANA SHARAN

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      The interplay between host immunity and tumour cells has opened the possibility of targeting tumour cells bymodulation of the human immune system. Cancer immunotherapy involves the treatment of a tumour by utilizing therecombinant human immune system components to target the pro-tumour microenvironment or by revitalizing theimmune system with the ability to kill tumour cells by priming the immune cells with tumour antigens. In this review,current immunotherapy approaches to cancer with special focus on dendritic cell (DC)-based cancer vaccines arediscussed. Some of the DC-based vaccines under clinical trials for various cancer types are highlighted. Establishingtumour immunity involves a plethora of immune components and pathways; hence, combining chemotherapy,radiation therapy and various arms of immunotherapy, after analysing the benefits of individual therapeutic agents,might be beneficial to the patient.

    • Expression of H19 long non-coding RNA is down-regulated in oral squamous cell carcinoma

      SUPRIYA VISHWAKARMA RITU PANDEY RENU SINGH RAGINI GOTHALWAL ASHOK KUMAR

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      Long non-coding RNAs (lncRNAs) are a group of non-protein-coding RNAs which are longer than 200nucleotides. LncRNAs play important roles in epigenetic modification, transcription and post-transcriptionalregulation, maintenance of normal tissue development and differentiation. LncRNA could serve as a biomarkerfor diagnosis and prognosis as well as a molecular target for therapy in oral squamous cell carcinoma (OSCC).Therefore, we have determined the expression profile of 5-lncRNAs namely UCA1, TUG1, HOTAIR,MALAT1, and H19 by quantitative real-time PCR in tumor tissues and adjacent normal tissue of 32 OSCCpatients. To determine the expression, methylation status and genomic alterations in lncRNAs across pancancer,TCGA datasets were analyzed by UALCAN, MEXPRESS and cBioPortal database. Then, we determinedthe association between lncRNA expression and clinicopathological attributes of patients by Spearman’srank test. Expression of UCA1 and TUG1 genes was up-regulated in 54.83% and 53.12% OSCC tumors,respectively. Importantly, expression of MALAT1 and H19 was down-regulated in tumor tissues of 62.5% and81.25% respectively of OSCC patients. Except for MALAT1, our experimental data showed concordance withthe TCGA analysis. Expression of HOTAIR in OSCC tumors was positively correlated with tumor volume,whereas MALAT1 and H19 negatively correlated with the smoking status of patients.

    • An RNAi-independent role of AP1-like stress response factor Pap1 in centromere and mating-type silencing in Schizosaccaromyces pombe

      ASHOK KUMAR JAGPREET SINGH NANDA SHARANJOT SAINI JAGMOHAN SINGH

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      Gene silencing in S. pombe occurs by heterochromatin formation at the centromere (cen), mating-type (mat)and telomere loci. It is mediated by silencing factors including Swi6, Clr1-4, Rhp6 and Pol-alpha. RNAi pathwayalso plays a role in establishment of silencing at the mat and cen loci. Recently, the stress response factors, Atf1and Pcr1were shown to play an RNAi-independent role in silencing at the mat3 locus through a cis-actingAtf1-binding site located within the repression element REIII and recruitment of the silencing factors Clr3 andClr6. Another cis-acting site, named repression element REII abutting the mat2 locus, also establishes heterochromatinstructure through Clr5 and histone deacetylases but independently of H3-Lys9-methylation andRNAi. Here, we report the occurrence of binding sites for another oxidative response factor, the pombe AP1-like factor Pap1, at the mating-type, centromere and telomere loci. By genetic studies we show that these sitesplay a role in silencing at the outer repeats of centromeres as well as mating-type locus and this effect ismediated through Pap1 binding site and interaction with and recruitment of the HP1/Swi6. Importantly, pap1-Deltacells display a silencing defect even in absence of the oxidative stress. Such a role of Pap1 in heterochromatinformation may be evolutionarily conserved.

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