RhoGTPases as Key Players in Mammalian Cell Adaptation to Microgravity

Figure 3

Role of AMPc on RhoGTPases activities and commitment of multipotent cells. Microgravity affects the growth, proliferation, and differentiation of multipotent cells by increasing AMPc production. AMPc contributes to cytoskeleton reorganization as it regulates negatively RhoA activity. Limitation of osteoblastogenesis might be linked to the ability of microgravity to reduce RhoA and Rac1 activities. RhoA and Rac1 activations support osteoblasts differentiation for their respective role in ERK activation and beta-catenin nuclear translocation. Sustained adipogenesis observed in microgravity-related condition might be linked to ability of AMPc to trigger integrin a5b1/a6b1 switch. Signaling through a6b1 integrin is known to support adipogenesis. A direct activation of adipogenic transcription factors (cEBPs) by AMPc has been also described.