These expression patterns are in keeping with organ-specific roles in development, as revealed by studies of gene-targeted mice (6, 8C11)

These expression patterns are in keeping with organ-specific roles in development, as revealed by studies of gene-targeted mice (6, 8C11). autocrine SDF-1/CXCR4 signaling in these cells. We propose that these novel effects of SDF-1 are relevant to the pathogenic and developmental roles of SDF-1 in the CNS. Introduction Stromal-derived cell factor-1 (SDF-1) was first described as a factor produced by bone marrow stromal cells that induces proliferation of B cell progenitors and regulates B cell maturation (1, 2). Two isoforms (SDF-1 and SDF-1) are encoded by a single gene and arise by alternative splicing (2). SDF-1 is the unique biological ligand for CXCR4, a high-affinity seven-transmembrane G proteinCcoupled receptor (3C5). Acting on CXCR4, SDF-1 exerts chemoattractant effects on target IDO-IN-12 cells and IDO-IN-12 mediates critical retentive functions towards pre-B cells, maintaining their presence in an appropriate microenvironment for development (6). Among chemokine/chemokine-receptor pairs, SDF-1 and CXCR4 exhibit atypical expression patterns: SDF-1 is usually constitutively produced in many organs and CXCR4 is found widely in both hematopoietic and other tissues (3C5, 7), indicating functions beyond inflammation and hematopoietic development. During organogenesis, SDF-1 and CXCR4 have dynamic and complementary expression patterns in neural, vascular, hematopoietic, and craniofacial systems (7). These expression patterns are consistent with organ-specific IDO-IN-12 roles in development, as revealed by studies of gene-targeted mice (6, 8C11). CXCR4 is usually a coreceptor for T-tropic HIV, and SDF-1 inhibits CXCR4-mediated HIV-1 contamination in vitro (3C5). Signaling molecules associated with the response to SDF-1 in hematopoietic cells have recently been clarified; these include Erk1/2 mitogen-activated protein kinase (Erk1/2 MAPK), Pyk-2, paxillin, Crk, protein kinase B, phosphatidylinositol 3-kinase, and NF-B (12C17). The Janus kinase (JAK) and signal transducer and activator of transcription (STAT) system has also been implicated in this pathway (18). In the CNS, SDF-1 has been detected predominantly in astrocytes. CXCR4 is expressed on both neurons and glial cells (19C24). Beyond their roles in cerebellar development, SDF-1 and CXCR4 appear to be involved in diverse pathological processes, including AIDS-associated neurologic disorders and proliferation of glioblastoma tumor cells (25). HIV-associated dementia (HAD) is usually a common complication of the late stages of viral contamination characterized pathologically by reactive astrogliosis, macrophage activation and accumulation, neuron loss, and defective blood-brain barrier (25C27). Increased astrocyte cell death in the CNS of HAD patients was recently shown to be associated with severe neurologic impairment (28). It is believed that neuronal cell death is caused indirectly by soluble factors secreted by HIV-infected or HIV-activated macrophages and glial cells. Most attention has focused on HIV-1 proteins (HIV gp120 and Tat) and proinflammatory cytokines (TNF- and IL-1). However, SDF-1 expression is usually upregulated in the brains of patients dying with HAD, and binding of SDF-1 to CXCR4 elicits neuronal apoptosis in vitro (15, 29), implicating pathological roles of SDF-1 in development of HAD. TNF- is usually expressed during immune-mediated CNS inflammation and AIDS dementia IDO-IN-12 (25). TNF- expression is usually regulated mainly at the level of transcription, and the diverse biological functions of TNF- are mediated through complex intracellular signaling pathways (30). In general, TNF- activates two signaling pathways, one leading to the activation of gene transcription and the other leading to cell death. Cytotoxic effects of TNF- involve receptor-dependent apoptosis mediated through the action of death-domain-containing proteins. TNF-Cinduced gene transcription events are primarily dependent on the activation and translocation of NF-B. In some experiments, activation of NF-B can mediate Mouse monoclonal to BMPR2 antiapoptotic actions of TNF- (31, 32). The transcription factor NF-B plays a critical role in immune and inflammatory responses. NF-B, a prototypic heterodimer of p50 and p65 (Rel-A), is usually sequestered in the cytoplasm through association with cellular inhibitors, members of the IB family of proteins (IBs). Upon exposure IDO-IN-12 to a wide variety of agents, most notably TNF- and IL-1, IBs are phosphorylated by IB kinases and then undergo ubiquitination and degradation in proteosomes, a rapid process independent of protein synthesis that allows the subsequent nuclear translocation of NF-B (33, 34). Once in the nucleus, NF-B binds a cognate luciferase) and 0.05 g of pRL-TK plasmid DNA (expressing luciferase) for 3 hours at 37C, using FuGENE 6 reagents according to the manufacturers protocols (Roche Molecular Biochemicals, Indianapolis, Indiana, USA). Cells were washed with PBS and treated with the indicated stimuli in 1 ml of DMEM at 37C for 6 hours. Luciferase activity was analyzed using the Dual-Luciferase.