The multiple faces of calcineurin signaling in Caenorhabditis elegans: Development, behaviour and aging.

Calcineurin, a well-conserved protein phosphatase 2B (PP2B), is a Ca2+-calmodulin–dependent serine/threonine protein phosphatase that is known to be involved in a myriad of cellular processes and signal transduction pathways. The biological role of calcineurin has been extensively studied in diverse groups of organisms. Homologues of mammalian and Drosophila calcineurin subunits exist in the nematode, Caenorhabditis elegans. The C. elegans counterpart of the catalytic subunit, calcineurin A, cna-1/tax-6, and the regulatory subunit, calcineurin B, cnb-1, are known to express ubiquitously in multiple tissues including neurons. The characterization of C. elegans calcineurin mutants facilitates identification of its physiological functions and signaling pathways. Genetic interactions between cna-1/tax-6 and cnb-1 mutants with a number of mutants involved in several signaling pathways have exemplified the pivotal role of calcineurin in regulating nematode development, behaviour and lifespan (aging). The present review has been aimed to provide a succinct summary of the multiple functions of calcineurin in C. elegans relating to its development, fertility, proliferation, behaviour and lifespan. Analyses of cna-1/tax-6 and cnb-1 interacting proteins and regulators of the phosphatase in this fascinating worm model have an immense scope to identify potential drug targets in various parasitic nematodes, which cause many diseases inflicting huge economic loss; and also for many human diseases, particularly neurodegenerative and myocardial diseases.

Protective effect of dietary phytochemicals against arsenite induced genotoxicity in mammalian V79 cells.

Chronic arsenic exposure causes skin diseases, gastrointestinal and neurological disorders, diabetes and cancer in various organs. Oxidative stress associated with arsenic exposure cause genetic instabilities and may initiate carcinogenesis. Phytochemicals present in vegetables, fruits, spices, tea, and medicinal plants, have shown to suppress experimental carcinogenesis in various organs. The aim of the present study was to elucidate the protective effect of some of the phytochemicals against the arsenite induced DNA damage in normal mammalian V79 cells. Comet assay was used for assessment of DNA damage and 2', 7'-dichlorofluorescein dihydroacetate for estimation of ROS generated by arsenite. The effect of the phytochemicals was observed during simultaneous treatment with arsenic, before arsenite exposure and during repair experiments. Of all the phytochemicals tested against arsenic, curcumin gave better protection during simultaneous treatment and resveratrol during pre treatment, which was evident both from comet assay and ROS generation experiments. During pre treatment a longer duration of treatment with lower dose of phytochemicals proved fruitful in reducing the genotoxicity. During repair experiments the phytochemicals enhanced recovery of DNA damage and ellagic acid gave promising results. The results indicated that natural phytochemicals may have the efficacy in reducing arsenic induced genotoxicity, in scavenging ROS and in enhancing the process of DNA repair in V79 cells.