Biennial Report 2005-2007 - Saha Institute of Nuclear Physics

Biophysical Sciences 215rates in chronically stressed V79 fibroblasts. We initially characterized the chronic oxidative stressresponse produced against H 2 O 2 exposure. At present we are characterizing in detail the cellularresponse to chronic heat stress at the molecular level. Cross-talk between the two forms of stressin the activation of key signaling elements such as p38MAPK, NFkB, and Akt/PKB and theirdownstream effectors such as Bcl-2, Bad, and heat shock proteins is also being studied.Soumyajit Banerjee Mustafi, Prabir Chakraborty, Prosenjit Sen, Sanghamitra RahaC& MB6.1.5.2 Cell death mechanisms in Entamoeba histolytica: association with activationof protein kinasesGenes encoding a mitogen activated protein kinase (MAPK) and an Akt/PKB kinase from thehuman enteric parasite, Entamoeba histolytica were identified. These protein kinases usually knownto be associated with survival or anti-apoptosis was cloned and expressed in bacteria. The role ofthe putative MAP kinase ( 40 kDa) and the Akt in growth inhibition of this parasite are beinginvestigated during heat stress, peroxide stress, and glucose deprivation. Cell death mechanisms inEntamoeba histolytica are also under investigation.Anupama Sardar, Doel Ray, Suman Dutta, Sanghamitra RahaC& MB6.1.5.3 Effects of natural products on the pro-survival signal transduction pathwaysin chronically stressed cells and cancer cellsThe cellular pro-survival pathways are extremely important because of their association with aberrantincreases in cellular mass in cancer cells. We found that Resveratrol (present in grapes)effectively counteracts the anti-apoptotic or pro-survival effects of chronic/repetitive stress throughinhibition of NFkB and Akt pro-survival pathways. Furthermore, we also studied the molecularbasis of the apoptosis-promoting effects of Resveratrol in cancer cells. We found that Resveratrolinhibits key signaling elements associated with cellular survival in chronic myeloid leukemia K562cells.Prabir Chakraborty, Soumyajit Banerjee Mustafi, Sanghamitra RahaC&MB6.1.5.4 Characterization of a p21 activated kinase (PAK) from Entamoeba histolyticaA p21 activated kinase was identified from Entamoeba genome data. The protein was cloned andexpressed. In the quest of the cellular function of this PAK, we studied the change in intracellularlocalisation of this PAK during stress. It was found that this PAK translocates to the insolublecytoskeleton during stress. Further, characterization of this protein kinase is in progress.Suman Dutta, Anupama Sardar, Sushanta Debnath, Sanghamitra RahaC&MB