Evidence for Ca²⁺‐ and ATP‐sensitive peripheral channels in nuclear pore complexes

Abstract

Six days of microgravity (Bion10 mission) induced dramatic shape changes in ROS 17/2.8 osteoblasts (7). During the Foton 11 and 12 space flights, we studied the kinetics (0-4 days) of ROS 17/2.8 morphology and adhesion, the relationships between adhesion and cell cycle progression after 4 days in space, and osteoblastic growth and activity after 6 days in space. Quantitative analysis of high-resolution adhesion [focal adhesion area imaged by total interference reflection fluorescent microscopy (TIRFM)] and integrin-dependent adhesion (imaged on confocal microscope by vinculin and phosphotyrosine staining) as well as cell cycle phase classification [Ki-67 staining, S-G2, mitotic cells and G1 (postmitotic cells)] were performed using programs validated in parabolic flight and clinostat. We observed disorganization of the cytoskeleton associated with disassembling of vinculin spots and phosphorylated proteins within focal contacts with no major change in TIRFM adhesion after 2 and 4 days of microgravity. Postmitotic cells, alone, accounted for the differences observed in the whole population. They are characterized by immature peripheral contacts with complete loss of central spots and decreased spreading. Osteocalcin, P1CP and alkaline phosphatase, and proliferation were similar in flight cells and 1 g centrifuge and ground controls after 6 days. In conclusion, microgravity substantially affected osteoblastic integrin-mediated cell adhesion. ROS17/2.8 cells responded differently, whether or not they were cycling by reorganizing adhesion plaque topography or morphology. In ROS 17/2.8, this reorganization did not impair osteoblastic phenotype.

Effects of oriented substrates on cell morphology, the cell cycle, and the cytoskeleton in Ros 17/2.8 cells

“…Similar responses were found in the current work where the cell area in the downward and edge-on orientations initially reduced within the first 3-day ( Figure 2A) before returning to the same level as that in the upward orientation, suggesting that the cell morphological remodeling to vector-directional gravity is duration-dependent. This remodeling was further observed from a slight lag-phase of cell growth in the downward and edge-on orientations at 24 or 48 h ( Figure 3A be- low), which was consistent with those observations under microgravity and in clinostat [18][19][20][21]26]. …”

“…Spaceflight induced a prolonged mitosis of MCF-7 cells and less focal adhesion sites in the post-mitosis of Ros 17/2.8 cells [19][20]. Dynamically vector-averaged gravity in clinostat enhanced the numbers of S-phase osteoblasts [10] but no significant difference in the G 2 /M-phase percentage was observed when Ros 17/2.8 cells were cultured under microgravity and on the ground [20]. In the current study, an enhancement in S-G 2 /M-phase percentage was found when Ros 17/2.8 cells were grown up in the downward orientation ( Figure 3C).…”

Differential Gene Regulation under Altered Gravity Conditions in Follicular Thyroid Cancer Cells: Relationship between the Extracellular Matrix and the Cytoskeleton

“…Rijken and de Groot were the first to demonstrate changes in cell shape in response to altered gravity in sounding rocket experiments [39]. Changes were also reported by Guignandon et al, who examined ROS/17/2.8 cells after a flight in an unmanned Foton mission, where they found a disorganization of the actin cytoskeleton [40].…”

cDNA microarray reveals the alterations of cytoskeleton-related genes in osteoblast under high magneto-gravitational environment

“…How do cells replicate and maintain their genomes, including the regulation of their proliferative capacity and survival? Studies reported that changes in cell shape and function were observed in response to changed gravity [10,11]. Our previous results also showed that simulated weightlessness by means of diamagnetic levitation markedly affected the cytoskeleton alteration of osteoblast (A.R.…”