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.

Spaceflight alters expression of microRNA during T‐cell activation

“…We confirmed the global gene array analysis of several of the target genes using qRT-PCR analysis. We have previously confirmed microgravity-mediated suppression of IL-2, IL-2-RA, EGR1, and INF-g gene expression in the immune response (10,13,14,18). Using qRT-PCR, we confirmed that microgravity-induced down-regulation of 4 of the miR-21 target genes, BTG2, TAGAP, SPRY2, and FASLG, as well as immune regulators NFKBIA and CD40LG genes (Fig.…”

“…Details of qRT-PCR methods have been previously published (10). At the end of the amplification period, melting curve analysis was performed to confirm the specificity of the amplicon.…”

“…Here we present our discovery of dysregulation of miRNA gene expression by gravity during early T-cell activation in spaceflight. We recently proved that the lack of immune response in microgravity occurs at the cellular level (10) and identified promoter regions, Abbreviations: AP1, activator protein 1; CD40LG, CD40 ligand; CPHI, cyclophilin A aka peptidyl prolyl isomerase A (PPIA); C t , threshold cycle; ISS, International Space Station; miRNA, microRNA; NASA, National Aeronautics and Space Administration; NFKBIA, nuclear factor of k light polypeptide gene enhancer in B-cell inhibitor a; PPIA, peptidyl prolyl isomerase A; qRT-PCR, quantitative real-time PCR; RT, reverse transcription transcription factors, and signal transduction pathways regulating human T-cell gene activation under normal and altered gravity conditions (10,13,14). To our knowledge, this is the first time that miRNAs have been analyzed using an onboard normal gravity control centrifuge eliminating possible confounders such as launch effects, cosmic radiation, and vibration, leaving only gravity conditions as a variable.…”

Magnesium Lithospermate B Protects Neurons Against Amyloid β (1–42)-Induced Neurotoxicity Through the NF-κB Pathway

“…A large number of genes involved in the pathogenesis of AD have been reported to Feng Jiang and Yongqiang Mao have contributed equally to this study. be under immediate-early transcriptional control of NF-jB [7]. Researchers also found that activated NF-jB can be detected in neuronal nuclei proximal to early stage senile plaques in AD brains, and that Ab is able to activate NF-jB in primary neurons [8].…”

Signal Transduction in Primary Human T Lymphocytes in Altered Gravity During Parabolic Flight and Clinostat Experiments

“…Many studies have revealed strong effects of microgravity on immune cell function [9,10,11], which were performed during manned space flights, on board of orbital, suborbital (sounding rockets) and parabolic flights, and were supported by ground-based facilities for simulation of microgravity such as clinorotation and 3D-random positioning machines [12]. Gravity-sensitivity in T lymphocytes was found for the cell cycle regulation [13], epigenetic regulation [14], chromatin regulation [15], expression profile of microRNA [16], cell motility [17], regulation of apoptosis [18], expression of cytokines [19], and expression of early genes of T lymphocyte activation, which are regulated primarily by the transcription factors NF-κB, CREB, ELK, AP-1, and STAT [13,20,21]. Taken together, the phenomenon of reduced activation of T cells and alterations in several cellular processes during microgravity is well described.…”