We do not know the processes that create these two distinct populations of responsive and non-responsive CD4 T cells in aged mice. T lymphocytes is composed of actin filaments, microtubules and intermediate filaments. The actin filaments (or F-actin) and the associated signaling 1-Methyladenosine machinery control many aspects of cell motility and provide the kinetic pressure that techniques T cells (Samstag et 1-Methyladenosine al., 2003;Smith et al., 2007;Long et al., 2004;Pribila and Shimizu, 2003;Hogg et al., 2004); these systems also control the morphology and plasticity of T cells (Cogoli-Greuter et al., 2004;Dustin et al., 2004;Dustin, 2007;Krummel and Macara, 2006;Meiri, 2004;Miyamoto et al., 2003;Poenie et al., 2004;Pribila and Shimizu, 2003). The microtubule system is thought to regulate the polarized secretion of effector molecules and might contribute to receptor endocytosis as well as to the maintenance of F-actin dependent structures (Rey et al., 2007;Stradal et al., 2006;Bossi and Griffiths, 2005;Huse et al., 2008;Track et al., 2008;Gomez and Billadeau, 2008). The role of intermediate filaments is usually less well comprehended, but these are thought to provide architectural support and regulate the rigidity of T cells (Minin and Moldaver, 2008;Cai and Sheetz, 2009;Goldberg et al., 2008). Therefore, the cytoskeleton controls many aspects of T 1-Methyladenosine cell function and plays an essential role in cell homing, and in interactions with antigen presenting cells that lead to T cell activation (Dustin, 2005;Dustin, 2006;Dustin, 2007;Dustin, 2008b;Dustin, 2008a). With age, there is a significant decline in T cell function. Studies have shown that with age there is a significant decline in IL-2 production (Clise-Dwyer, 2007), while studies in our lab have shown defects in early TCR signals of CD4 T cells from aged mice (for a review seeMiller et al., 1997;Miller et al., 2005). In particular, CD4 T cells from aged mice show defects in the translocation of talin during early phases of their conversation with APC, before the TCR starts to discriminate between agonist and antagonist peptide (Garcia and Miller, 2001) and defects in the translocation of many other key-signaling proteins to the area of APC-T cell conversation. These defects in translocation lead to a lack of immune synapse formation (Garcia and Miller, 2001;Garcia and Miller 2003). Additional work showed that downstream pathways of the TCR are also affected by age, including Raf-1 and JNK signaling (Kirk and Miller, 1999;Kirk et al., 1999;Kirk and Miller, 1998) and revealed defects in NFAT nuclear translocation (Garcia and Miller, 2001;Garcia and Miller, 2003). The data suggest that defects in early aspects of TCR signaling may be in part responsible for the declines in cytokine production, including IL-2. In addition to our studies, other groups have shown that CD4 T cells from aged mice show significant defects in proliferation (Haynes and Swain, 2006) and differentiation into memory or effectors cells (Vallejo, 2006;Hakim and Gress, 2007;Haynes and Eaton, 2005;Haynes, 2005;Haynes and Swain, 2006). The published data suggested a clear age-related decline in CD4 T cell function, but less is known about how age affects cytoskeleton structure and function, and how such changes might affect immunological synapse formation and later stages of T cell activation and function. Although it is likely that age could impact many aspects of the cytoskeletal structure and contribute at many stages in the defects in the TCR signaling, this review will focus on KLF4 antibody events related to activation of CD4 T cells immediately after encounter with antigen presenting cells (APC); defects at this early stage are likely to 1-Methyladenosine be rate-limiting for T cell transition from resting cell to activated effector. In addition, you will find no studies in the effect of age on intermediate filaments of CD4 T cells that could help to clarify some of the age-related declines in CD4 function. We will in.
