Browsing by Author "Chaudhuri, Sibapriya"

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    Investigating the changes in phagosomal function in Porcine Reproductive and Respiratory Syndrome Virus infection
    (2013-09-27) Chaudhuri, Sibapriya; Yates, Robin
    Porcine Reproductive and Respiratory Syndrome is one of the most economically devastating diseases of the swine industry and affects all swine producing countries worldwide. The disease is caused by Porcine Reproductive and Respiratory Syndrome Virus (PRRSV). The virus is macrophage-tropic and infects tissue macrophages in the host animal. However, nothing is known about how the phagosome lumenal microenvironment in the macrophages may be modified in PRRSV infection. Such knowledge is crucial for understanding how microbicidal and antigen presentation functions of the macrophage may be compromised during PRRSV infection. The field of PRRSV biology also suffers from the dearth of existence of a good in vitro system for studying the virus biology in a methodical and reductionist fashion. This thesis establishes an in vitro system for studying PRRSV infection. Using this newly established in vitro system of PRRSV infection in porcine bone marrow derived macrophages, this study investigates how the phagosome microenvironment changes in porcine macrophages in PRRSV infection. This study also investigates how phagosome lumenal properties are modified in porcine alveolar macrophages isolated from PRRSV infected pregnant gilts.
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    Protein phosphatase 2A-B56 regulates mitosis by interacting with LS/TPI/V motif containing proteins
    (2019-10-18) Chaudhuri, Sibapriya; Moorhead, Greg B. G.; Zaremberg, Vanina; Ng, Kenneth Kai Sing; Holmes, Charles F. B.
    Reversible protein phosphorylation is an important post translational modification that controls diverse signaling pathways including the eukaryotic cell cycle signaling. Protein phosphatase 2A (PP2A) is a highly conserved protein phosphatase that removes phosphate groups from serine/threonine residues on proteins. PP2A is a trimeric enzyme consisting of a catalytic or C subunit, a scaffolding or A subunit and a regulatory or B subunit. In humans, B56 is one of the four families of B subunits. PP2A-B56 is an important mitotic protein phosphatase that is essential for proper execution of several mitotic events such as alignment and segregation of sister chromatids. The primary objective of this study was to understand the mechanisms that controls interaction between PP2A-B56 and its mitotic interactors. This study shows that PP2A-B56 interacts with important mitotic regulators through a LS/TPI/V motif. The LS/TPI/V proteins are widespread in the human proteome and are conserved across eukaryotes. The LS/TPI/V proteins take part in multiple signaling pathways including the eukaryotic cell cycle. The interaction between PP2A-B56 and the LS/TPI/V proteins occur in an isoform dependent and phosphorylation dependent manner. Among the five isoforms of B56, B56 gamma 3 and B56 delta have a preference for binding to dephosphorylated LS/TPI/V peptides. The LS/TPI/V motif gets phosphorylated as the cell enters prophase and gets dephosphorylated at mitotic exit. This phosphorylation event is controlled by Aurora Kinase B. B56 delta has a preference for binding to LS/TPI/V proteins when the motif is dephosphorylated. This preference is contributed by the C terminal tail of B56 delta.