Rapid alterations of cell cycle control proteins in human T lymphocytes in microgravity

Abstract

In our study we aimed to identify rapidly reacting gravity-responsive mechanisms in mammalian cells in order to understand if and how altered gravity is translated into a cellular response. In a combination of experiments using "functional weightlessness" provided by 2D-clinostats and real microgravity provided by several parabolic flight campaigns and compared to in-flight-1g-controls, we identified rapid gravity-responsive reactions inside the cell cycle regulatory machinery of human T lymphocytes. In response to 2D clinorotation, we detected an enhanced expression of p21 Waf1/Cip1 protein within minutes, less cdc25C protein expression and enhanced Ser147-phosphorylation of cyclinB1 after CD3/CD28 stimulation. Additionally, during 2D clinorotation, Tyr-15-phosphorylation occurred later and was shorter than in the 1 g controls. In CD3/CD28-stimulated primary human T cells, mRNA expression of the cell cycle arrest protein p21 increased 4.1-fold after 20s real microgravity in primary CD4+ T cells and 2.9-fold in Jurkat T cells, compared to 1 g in-flight controls after CD3/CD28 stimulation. The histone acetyltransferase (HAT) inhibitor curcumin was able to abrogate microgravity-induced p21 mRNA expression, whereas expression was enhanced by a histone deacetylase (HDAC) inhibitor. Therefore, we suppose that cell cycle progression in human T lymphocytes requires Earth gravity and that the disturbed expression of cell cycle regulatory proteins could contribute to the breakdown of the human immune system in space.

Ground-Based Facilities for Simulation of Microgravity: Organism-Specific Recommendations for Their Use, and Recommended Terminology

“…Waf1/Cip1 protein expression was reduced 4.2-fold after 15 min in 1g but was enhanced 1.6-fold after 15 min during clinorotation (2-D testtube clinostat, 60 rpm, pipette inner radius 1.5 mm, maximal residual acceleration 6 · 10 -3 g, 37°C) (Thiel et al, 2012). In addition to the protein expression, mRNA transcription levels were analyzed by real-time PCR.…”

Effects of simulated weightlessness on cellular morphology and biological characteristics of cell lines SGC-7901 and HFE-145

“…Cell cycle control proteins in human T lymphocytes showed altered microgravity (Thiel et al, 2012). Microgravity caused increased apoptosis in human thyroid cells (Kossmehl et al, 2003) and human endothelial cells (Infanger et al, 2006b).…”

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.…”