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Background/Aims: Cardiovascular complications are common in astronauts returning from a prolonged spaceflight. These health problems might be driven by complex modulations of gene expression and protein synthesis in endothelial cells (ECs). Studies on the influence of microgravity on phenotype, growth pattern and biological processes of ECs can help to understand these complications. Methods: We exposed ECs (EA.hy926) to a Random Positioning Machine (RPM). Proteins associated with cell structure, angiogenesis and endothelial dysfunction were investigated in distinct pools of multicellular spheroids (MCS), adherent cells (AD) and tubular structures (TS) formed after a 35-day RPM-exposure. Results: Combining morphological and molecular approaches, we found AD, MCS and TS with changes in the synthesis and release of proteins involved in three-dimensional growth. Fibronectin and monocyte chemoattractant protein-1 (MCP-1) mRNAs and protein contents were elevated along with an increased secretion of vascular endothelial growth factor (VEGF), interleukin (IL)-6, IL-8, MCP-1, intercellular adhesion molecule 1 (ICAM-1), vascular cell adhesion molecule 1 (VCAM-1), neutrophil gelatinase-associated lipocalin (NGAL) and regulated on activation, normal T cell expressed and secreted (RANTES) proteins in the culture supernatant as determined by multianalyte profiling technology. Together they form a network of interaction. Conclusions: These results show that a prolonged RPM-exposure of ECs induced TS and MCS formation. The factors VEGF, NGAL, IL-6, IL-8, MCP-1, VCAM-1, ICAM-1, fibronectin and RANTES seem to be affected when gravity is omitted.

Microgravity induces three-dimensional (3D) growth in numerous cell types. Despite substantial efforts to clarify the underlying mechanisms for spheroid formation, the precise molecular pathways are still not known. The principal aim of this paper is to compare static 1g-control cells with spheroid forming (MCS) and spheroid non-forming (AD) thyroid cancer cells cultured in the same flask under simulated microgravity conditions. We investigated the morphology and gene expression patterns in human follicular thyroid cancer cells (UCLA RO82-W-1 cell line) after a 24 h-exposure on the Random Positioning Machine (RPM) and focused on 3D growth signaling processes. After 24 h, spheroid formation was observed in RPM-cultures together with alterations in the F-actin cytoskeleton. qPCR indicated more changes in gene expression in MCS than in AD cells. Of the 24 genes analyzed VEGFA, VEGFD, MSN, and MMP3 were upregulated in MCS compared to 1g-controls, whereas ACTB, ACTA2, KRT8, TUBB, EZR, RDX, PRKCA, CAV1, MMP9, PAI1, CTGF, MCP1 were downregulated. A pathway analysis revealed that the upregulated genes code for proteins, which promote 3D growth (angiogenesis) and prevent excessive accumulation of extracellular proteins, while genes coding for structural proteins are downregulated. Pathways regulating the strength/rigidity of cytoskeletal proteins, the amount of extracellular proteins, and 3D growth may be involved in MCS formation.

We present a quantitative evaluation of Golgi-impregnated columnar neurons in the optic lobe of wild-type Drosophila melanogaster. This analysis reveals the overall connectivity pattern between the 10 neuropil layers of the medulla and demonstrates the existence of at least three major visual pathways. Pathway 1 connects medulla layer M10 to the lobula plate. Input layers of this pathway are M1 and M5. Pathway 2 connects M9 to shallow layers of the lobula, which in turn are tightly linked to the lobula plate. This pathway gets major input via M2. Pathways 1 and 2 receive input from retinula cells R1-6, either via the lamina monopolar cell L1 (terminating in M1 and M5) or via L2 and T1 (terminating in M2). Neurons of these pathways typically have small dendritic fields. We discuss evidence that pathways 1 and 2 may play a major role in motion detection. Pathway 3 connects M8 to deep layers of the lobula. In M8 information converges that is derived either from M3 (pathway 3a) or from M4 and M6 (pathway 3b), layers that get their major input from L3 and R8 or L4 and R7, respectively. Some neurons of pathway 3 have large dendritic fields. We suggest that they may be involved in the computation of form and colour. Possible analogies to the organization of pathways in the visual system of vertebrates are discussed.

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