It is a universal process used to control the amount and spatiotemporal expression of genes. Gene regulation is the key factor to the ability of a cell or an organism to sustain life and respond to environmental changes. It has been known for many years that real (r-) and simulated (s-) µ g induce various changes in cells, microorganisms, animals, and plants.

After the spaceflight, many astronauts continue to experience back pain and report problems with the intervertebral discs. Since the spine is stretched by µ g and becomes almost straight, the astronauts’ height increases by up to 7.5 cm on the International Space Station (ISS). Other health problems are space flight-associated neuro-ocular syndrome (SANS) and back pain. In addition, many astronauts suffer from space travel-sickness, the so-called space adaptation syndrome (SAS), associated with nausea and vomiting. Cardiovascular problems comprise arrhythmias, cardiac atrophy, low blood pressure, and orthostatic intolerance. In addition, space travelers excrete around 1.5 L of urine during the first few hours in space. Furthermore, there is an increase in heart filling and diuresis, which leads to an overall reduction in blood volume and an elevation in hematocrit. Under µ g conditions, the fluid becomes displaced into the chest and head (so-called ‘puffy face’), and the astronauts exhibit ‘bird legs’ (very slender legs). For example, standing upright on Earth gathers fluid in the lower extremities. Therefore, detailed medical examinations have been performed on humans reporting various health problems occurring early and late during space missions. Normally, all Earth’s creatures are accustomed to gravity’s force, and gravity changes will significantly influence these organisms’ health and function. In addition, on their journey to the Moon and Mars, humans in space will live under the influence of the different gravity levels ranging from 1 g to real (r-) µ g conditions on the Moon (0.17 g) or Mars (0.376 g). While conquering space, astronauts, cosmonauts, and taikonauts, together with space tourists, will face microgravity (µ g) and cosmic radiation, among other stressors. Importantly, the obtained data clearly imply that µ g experiments can support translational medicine on Earth. In particular, we discuss the current knowledge about the impact of microgravity on gene regulation in different types of bacteria, protists, fungi, animals, humans, and cells with a focus on the brain, eye, endothelium, immune system, cartilage, muscle, bone, and various cancers as well as recent findings in plants.

In this review, we provide an overview of µ g-induced changes in the numerous mechanisms involved in gene regulation, including regulatory proteins, microRNAs, and the chemical modification of DNA. It is a universal process to control the amount, location, and timing in which genes are expressed. Gene regulation is a key factor in a cell or an organism’s ability to sustain life and respond to environmental changes. In particular, cancer and metastasis research benefits from the findings obtained under µ g conditions. As crewed spaceflights into deep space are being planned along with the commercialization of space travelling, researchers have focused on gene regulation in cells and organisms exposed to real (r-) and simulated (s-) µ g. Microgravity changes the proliferation, differentiation, and growth of cells. Microgravity (µ g) has a massive impact on the health of space explorers.

Moon traveler bottle rocket