Principal Investigator - Prof. K. VijayRaghavan and Prof. Mani Ramaswami ( Trinity College, Dublin)Project – Transcriptional Consequences of Stress Granule Assembly and Clearance Protein clearance mechanisms play a major role in maintaining homeostasis. Defective protein clearance is seen in neurodegeneration. My project aimed to elucidate the pathways that change upon formation and clearance of stress granules. I performed cell stress and recovery experiments with and without the stress granule nucleation factor, followed by transcriptomic analysis to identify the up and down-regulated pathways. I concluded that the transcriptional response of cells to stress is independent of stress granule assembly and clearance. Project – Establishing an in vivo Muscle Degeneration Model Neurons and muscles although different tissues have similar properties. They undergo continuous high metabolic turnover and exposure to cellular damage over a lifetime further increases cellular dysfunction. We therefore decided to establish an in vivo muscle degeneration model in D. melanogaster by specifically overexpressing toxic protein mutants that are implicated in neurodegeneration, in flight muscles. We quantified the phenotypes using micro-computed tomography. We conclude that these proteins also damage muscles in an age-dependent manner and the phenotypes can be rescued by co-expressing cytoprotective proteins. Project – Heterogeneous distribution of mRNAs within flight muscle fibers Drosophila flight muscle fibers are fibrillar in nature and share several similarities with human skeletal muscles even at the sarcomere level. We asked if these long fibers spanning the entire length of the thorax have differential transcript expression along the length of the muscle. For this, we dissected the flight muscles in 3 parts: Anterior, Middle, and Posterior, and found significant differences, suggesting different functional consequences along the length of the muscle.

Project - Molecular Characterization of Ataxin-2 Stress GranulesPrincipal Investigator - Prof. K. VijayRaghavan and Prof. Mani Ramaswami ( Trinity College, Dublin) Ataxin-2 protein is implicated in neurodegenerative diseases such as SCA2 and ALS. These diseases are primarily caused by defective protein clearance which leads to aggregation of unfolded proteins into cytotoxic granules. My study was aimed at understanding composition, dynamics and clearance mechanism of these granules using D. melanogaster S2R+ cell line. My primary aim was to maintain healthy cell cultures and perform vector transfections followed by immunostaining and confocal microscopy and data analysis with ImageJ. Project - Establishing in vivo model of neurodegeneration in D. melanogaster larval brainI established a neurodegeneration model in larval brain of D. melanogaster by feeding sodium arsenite and quantifying increase in the Ataxin-2 stress granules which are indicative of neurodegeneration phenotype.

Project - Characterization of GRAF as tumor suppressorPrincipal Investigator - Prof. L.S ShashidharaGRAF – GTPase Regulator Associated with Focal Adhesion Kinase (ARHGAP26) is a Rho-GAP protein which is involved in endocytosis, actin remodeling, and cell migration. It has been linked to diseases such as gastric cancer, Acute Myeloid Leukemia (AML), Myelodsyplastic Syndrome, Mixed-Lineage Leukemia (MLL), cerebellar ataxia, oncogenesis and tumor progression. Here, based on the literature studies, we hypothesized that GRAF might act as tumor suppressor. We partly confirmed this hypothesis by knockdown of RNAi and simultaneously over-expressing Yorkie (Yki) in M. Drosophila imaginal wing discs. The data indicates that there is significant tissue overgrowth with increased folds in the disc. Moreover, large no. of cells were seen in mitotic phase which further supports the literature studies that GRAF knockdown might act through RhoA to down-regulate p21, which leads to G1-to-S phase transition.

During my visit at NIRT, Chennai, I was exposed to working principle and application of Mass Spectrometry and Flow Cytometry.