title: The Rel/NF-κB pathway and transcription of immediate early genes in T cell activation are inhibited by microgravity.
abstract: This study tested the hypothesis that transcription of immediate early genes is inhibited in T cells activated in μg. Immunosuppression during spaceflight is a major barrier to safe, long-term human space habitation and travel. The goals of these experiments were to prove that μg was the cause of impaired T cell activation during spaceflight, as well as understand the mechanisms controlling early T cell activation. T cells from four human donors were stimulated with Con A and anti-CD28 on board the ISS. An on-board centrifuge was used to generate a 1g simultaneous control to isolate the effects of μg from other variables of spaceflight. Microarray expression analysis after 1.5 h of activation demonstrated that μg- and 1g-activated T cells had distinct patterns of global gene expression and identified 47 genes that were significantly, differentially down-regulated in μg. Importantly, several key immediate early genes were inhibited in μg. In particular, transactivation of Rel/NF-κB, CREB, and SRF gene targets were down-regulated. Expression of cREL gene targets were significantly inhibited, and transcription of cREL itself was reduced significantly in μg and upon anti-CD3/anti-CD28 stimulation in simulated μg. Analysis of gene connectivity indicated that the TNF pathway is a major early downstream effector pathway inhibited in μg and may lead to ineffective proinflammatory host defenses against infectious pathogens during spaceflight. Results from these experiments indicate that μg was the causative factor for impaired T cell activation during spaceflight by inhibiting transactivation of key immediate early genes.
authors: Department of Surgery, University of California, San Francisco, CA, USA. tammy.chang@ucsf.edu
authors: Tammy T
authors: TT
authors: Chang
authors: Isabelle
authors: I
authors: Walther
authors: Chai-Fei
authors: CF
authors: Li
authors: Jim
authors: J
authors: Boonyaratanakornkit
authors: Grazia
authors: G
authors: Galleri
authors: Maria Antonia
authors: MA
authors: Meloni
authors: Proto
authors: P
authors: Pippia
authors: Augusto
authors: A
authors: Cogoli
authors: Millie
authors: M
authors: Hughes-Fulford
mesh_terms: D018106:CD28 Antigens / Q000378:metabolism; D017252:CD3 Complex / Q000378:metabolism; D015496:CD4-Positive T-Lymphocytes / Q000378:metabolism; D016000:Cluster Analysis; D020869:Gene Expression Profiling; D005786:Gene Expression Regulation; D053263:Gene Regulatory Networks; D017781:Genes, Immediate-Early; D006801:Humans; D008213:Lymphocyte Activation / Q000235:genetics*; D016328:NF-kappa B / Q000378:metabolism*; D015398:Signal Transduction; D013601:T-Lymphocytes / Q000378:metabolism*; D051996:Transcription Factor RelA / Q000378:metabolism*; D014158:Transcription, Genetic; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism; D014893:Weightlessness
chemical_list: D018106:CD28 Antigens; D017252:CD3 Complex; D016328:NF-kappa B; D051996:Transcription Factor RelA; D014409:Tumor Necrosis Factor-alpha