Articles written in Journal of Biosciences

    • PTP-S2, a nuclear tyrosine phosphatase, is phosphorylated and excluded from condensed chromosomes during mitosis

      Sundaram Nambirajan Vegesna Radha Shubhangi Kamatkar Ghanshyam Swarup

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      PTP-S2 is a tyrosine specific protein phosphatase that binds to DNA and is localized to the nucleus in association with chromatin. It plays a role in the regulation of cell proliferation. Here we show that the subcellular distribution of this protein changes during cell division. While PTP-S2 was localized exclusively to the nucleus in interphase cells, during metaphase and anaphase it was distributed throughout the cytoplasm and excluded from condensed chromosomes. At telophase PTP-S2 began to associate with chromosomes and at cytokinesis it was associated with chromatin in the newly formed nucleus. It was hyperphosphorylated and showed retarded mobility in cells arrested in metaphase.In vitro experiments showed that it was phosphorylated by CK2 resulting in mobility shift. Using a deletion mutant we found that CK2 phosphorylated PTP-S2 in the C-terminal non-catalytic domain. A heparin sensitive kinase from mitotic cell extracts phosphorylated PTP-S2 resulting in mobility shift. These results are consistent with the suggestion that during metaphase PTP-S2 is phosphorylated (possibly by CK2 or a CK2-like enzyme), resulting in its dissociation from chromatin.

    • The need to develop a framework for human-relevant research in India: Towards better disease models and drug discovery


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      The low translational efficiency of animal models to humans, and the development of new-age methodologiesthat are human-cell based, is fuelling a paradigm change across the globe. In this perspectives paper, wediscuss the current state of research, funding, and regulation in these 21st century technologies, includingorganoids and organ-on-chip in India. Recently, a road-map was drawn by Indian Council for MedicalResearch (ICMR) regarding alternatives to animals in research in India and it also held a special session inJanuary 2018 to discuss latest developments in new human-relevant model systems. We document the regulatoryand research landscape in this field in India. We also discuss the challenges present in this field whichinclude lack of training and skills to handle embryonic or induced pluripotent stem cell (iPSC) lines, fundinglimitations, lack of domestic production of reagents leading to elevated costs, and lack of infrastructure, such asmicrofabrication facilities. In the end, we provide recommendations to enable innovation and application ofhuman-relevant methodologies to develop India as a key player in this arena globally.

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