title: Reduced Expression of Cytoskeletal and Extracellular Matrix Genes in Human Adult Retinal Pigment Epithelium Cells Exposed to Simulated Microgravity.
abstract: OBJECTIVE
  Microgravity (µg) has adverse effects on the eye of humans in space. The risk of visual impairment is therefore one of the leading health concerns for NASA. The impact of µg on human adult retinal epithelium (ARPE-19) cells is unknown.
  
  
  METHODS
  In this study we investigated the influence of simulated µg (s-µg; 5 and 10 days (d)), using a Random Positioning Machine (RPM), on ARPE-19 cells. We performed phase-contrast/fluorescent microscopy, qRT-PCR, Western blotting and pathway analysis.
  
  
  RESULTS
  Following RPM-exposure a subset of ARPE-19 cells formed multicellular spheroids (MCS), whereas the majority of the cells remained adherent (AD). After 5d, alterations of F-actin and fibronectin were observed which reverted after 10d-exposure, suggesting a time-dependent adaptation to s-µg. Gene expression analysis of 12 genes involved in cell structure, shape, adhesion, migration, and angiogenesis suggested significant changes after a 10d-RPM-exposure. 11 genes were down-regulated in AD and MCS 10d-RPM-samples compared to 1g, whereas FLK1 was up-regulated in 5d- and 10d-RPM-MCS-samples. Similarly, TIMP1 was up-regulated in 5d-RPM-samples, whereas the remaining genes were down-regulated in 5d-RPM-samples. Western blotting revealed similar changes in VEGF, β-actin, laminin and fibronectin of 5d-RPM-samples compared to 10d, whereas different alterations of β-tubulin and vimentin were observed. The pathway analysis showed complementing effects of VEGF and integrin β-1.
  
  
  CONCLUSIONS
  These findings clearly show that s-µg induces significant alterations in the F-actin-cytoskeleton and cytoskeleton-related proteins of ARPE-19, in addition to changes in cell growth behavior and gene expression patterns involved in cell structure, growth, shape, migration, adhesion and angiogenesis.
authors.affiliation: Department of Biomedicine, Aarhus University, Aarhus, Denmark.
authors.forename: Thomas J
authors.initials: TJ
authors.lastname: Corydon
authors.forename: Vivek
authors.initials: V
authors.lastname: Mann
authors.forename: Lasse
authors.initials: L
authors.lastname: Slumstrup
authors.forename: Sascha
authors.initials: S
authors.lastname: Kopp
authors.forename: Jayashree
authors.initials: J
authors.lastname: Sahana
authors.forename: Anne Louise
authors.initials: AL
authors.lastname: Askou
authors.forename: Nils E
authors.initials: NE
authors.lastname: Magnusson
authors.forename: David
authors.initials: D
authors.lastname: Echegoyen
authors.forename: Toke
authors.initials: T
authors.lastname: Bek
authors.forename: Alamelu
authors.initials: A
authors.lastname: Sundaresan
authors.forename: Stefan
authors.initials: S
authors.lastname: Riwaldt
authors.forename: Johann
authors.initials: J
authors.lastname: Bauer
authors.forename: Manfred
authors.initials: M
authors.lastname: Infanger
authors.forename: Daniela
authors.initials: D
authors.lastname: Grimm
mesh_terms: D008841:Actin Cytoskeleton / Q000378:metabolism; D000199:Actins / Q000378:metabolism; D000328:Adult; D002448:Cell Adhesion; D049109:Cell Proliferation; D048430:Cell Shape; D003599:Cytoskeleton / Q000235:genetics* / Q000378:metabolism; D005109:Extracellular Matrix / Q000235:genetics* / Q000378:metabolism; D016326:Extracellular Matrix Proteins / Q000235:genetics / Q000378:metabolism; D005786:Gene Expression Regulation; D006801:Humans; D008954:Models, Biological; D010641:Phenotype; D055213:Retinal Pigment Epithelium / Q000378:metabolism*; D015398:Signal Transduction / Q000235:genetics; D042461:Vascular Endothelial Growth Factor A / Q000378:metabolism; D014893:Weightlessness
chemical_list: D000199:Actins; D016326:Extracellular Matrix Proteins; D042461:Vascular Endothelial Growth Factor A