Simulated Microgravity Induces Apoptosis in Human Lymphocytes by a 5-Lipoxygenase-Mediated Mechanism

Experiments performed during spaceflight clearly show that several cellular processes, such as oxidative metabolism, growth rates, signaling pathways and gene expression, are modified under conditions of weightlessness [1]. In particular, it has been suggested that reduced growth response in lymphocytes during spaceflight might be linked to apoptosis, based on morphological detection and cDNA microarray analysis [2] of space-flown human lymphoblastoid (Jurkat) cells. 5-Lipoxygenase (arachidonate:oxygen 5-oxidoreductase, EC 1.13.11.34; 5-LOX) plays a central role in interleukin-2 expression and activation of human lymphocytes, and is involved in the initiation of programmed death (apoptosis) triggered by unrelated stimuli in different human cells (reviewed in ref. 3). [...]