Interestingly, the age-related genes overlapping in the three tissues analyzed in this study all have functions related to the immune system and show in most cases increased expression with age. affecting the organism during its lifetime. In addition, we propose LPO as a potential biomarker of aging. == Electronic supplementary material == The online version of this article (doi:10.1007/s10522-009-9219-1) contains supplementary material, which is available to authorized users. Keywords:NFkappaB, Inflammation, Lipid hydroperoxides, Microarrays == Introduction == Research on the process of aging has revealed its complexity. This tenet is clearly demonstrated by the different theories of aging postulated over the last decades. Theories of aging fall into two broad categories: evolutionary Typhaneoside models which pertain to the selective forces which determine species variation in PLA2G4F/Z life span, and proximate mechanisms, which determine the molecular process underlying individual variation in life span. Examples of the evolutionary models include the antagonistic pleiotropy theory introduced by Williams (1957) and the disposable soma theory proposed by Kirkwood (1977). Proximate mechanisms invoke a variety of molecular agents and include, for example, the free radical and mitochondrial decline theory (Harman1956,1972), the cross-linking theory (Sinex1964), the Hayflick limit theory (Hayflick1965), the membrane theory of aging (Zs-Nagy1978), the neuroendocrine theory (Dilman et al.1986), and the metabolic stability theory (Demetrius2004). The implications of the free radical theory and the metabolic stability theorymodels which involve ROS production rate and homeostasis, respectivelyhave been addressed using microarray-based analysis of gene expression. These empirical studies (Brink et al.2008) have contributed to an increased awareness that aging is a systemic process which is driven by gene networks rather than a single-gene driven process (Budovskaya et al.2008). In mice, the first transcriptional profiles were generated in a limited number of mouse tissues such as muscle (Lee et al.1999) and brain (Lee et al.2000). Since then, transcriptional profiles of diverse organs and cells such as liver (Cao et al.2001; Amador-Noguez et al.2004; Fu et al.2006), brain (Jiang et al.2001; Fu et al.2006), cardiomyocytes (Bahar et al.2006), macrophages (Chelvarajan et al.2006), heart (Dhahbi et al.2006; Fu et al.2006), adipose tissue (Higami et al.2006), skeletal muscle (Edwards et al.2007), and lungs (Misra et al.2007) have been studied. In all of these studies, various tissues derived from mice of varying ages and strains were analyzed on varying platforms. A consequence of this is the noticeable differential expression in age-regulated target genes. A recent study (Zahn et al.2007) now investigated and compared the Typhaneoside transcriptional aging profiles of 16 mouse tissues. Overall, there is conservation of common biological processes related to aging, independent of tissue, strain, array platform etc. These processes include stress/immune responses, cell cycle, and metabolism. In human, numerous studies have been conducted investigating aging in brain (Lu et al.2004; Fraser et al.2005), blood (Tan et al.2005), eye (Segev et al.2005), kidney (Rodwell et al.2004; Melk et al.2005), muscle (Welle et al.2004; Giresi et al.2005; Zahn et al.2006), and skin (Lener et al.2006). The available data suggests that age-related stress/immune responses, cell cycle, and metabolism are conserved. In this work, we show by Typhaneoside gene expression profiling of three mouse tissues (brain, heart and kidney) that activation of the immune response is a conserved age-related process. In addition, age-related increase in LPO concentrations may be accounted for by an oxidative stress-mediated activation of NF-kB signaling. == Materials and methods == == Mice Typhaneoside == Healthy wild type female C57BL6 mice were housed in a room with controlled photoperiod and temperature. Animals were given free access to water and pelleted diet. Mice were sacrificed by cervical dislocation; tissues were collected and flash frozen in liquid nitrogen and stored at 80C. Brain, heart and kidneys were collected from young (810 weeks) and aged (1719 month) mice. This study was approved by the institutional ethical committee. == RNA isolation == Whole mouse tissues (brain, heart and kidney) were homogenized in 1 ml Trizol (Invitrogen, Carlsbad, CA, USA) Typhaneoside using the TissueLyser and 5 mm Stainless Steel Beads (Qiagen, Hilden, Germany) and homogenizing two times for 1 min at a frequency of 30.1/s. Homogenized samples were then incubated for 5 min at room heat range (RT). After addition of 200 l chloroform, vortex blending, incubation for 2 min at centrifugation and RT at 12,000gfor 15 min at 4C water stage was used in a new pipe. About 500 l isopropanol had been added as well as the mix was incubated for 10 min at RT and soon after centrifuged with 8,000gat 4C for 5 min. The supernatant was discarded as well as the pellet cleaned with 1 ml of 75% ethanol, vortexed, and centrifuged at 8,000gfor 5 min at 4C. The supernatant was discarded.