Acute transcriptional up-regulation specific to osteoblasts/osteoclasts in medaka fish immediately after exposure to microgravity

Abstract

Bone loss is a serious problem in spaceflight; however, the initial action of microgravity has not been identified. To examine this action, we performed live-imaging of animals during a space mission followed by transcriptome analysis using medaka transgenic lines expressing osteoblast and osteoclast-specific promoter-driven GFP and DsRed. In live-imaging for osteoblasts, the intensity of osterix- or osteocalcin-DsRed fluorescence in pharyngeal bones was significantly enhanced 1 day after launch; and this enhancement continued for 8 or 5 days. In osteoclasts, the signals of TRAP-GFP and MMP9-DsRed were highly increased at days 4 and 6 after launch in flight. HiSeq from pharyngeal bones of juvenile fish at day 2 after launch showed up-regulation of 2 osteoblast- and 3 osteoclast- related genes. Gene ontology analysis for the whole-body showed that transcription of genes in the category “nucleus” was significantly enhanced; particularly, transcription-regulators were more up-regulated at day 2 than at day 6. Lastly, we identified 5 genes, c-fos, jun-B-like, pai-1, ddit4 and tsc22d3, which were up-regulated commonly in the whole-body at days 2 and 6, and in the pharyngeal bone at day 2. Our results suggested that exposure to microgravity immediately induced dynamic alteration of gene expression levels in osteoblasts and osteoclasts.

Deep Transcriptomic Analysis of Black Rockfish (Sebastes schlegelii) Provides New Insights on Responses to Acute Temperature Stress

“…Early growth response protein 1 (EGR1) indicates that the DNA methylation status of the promoter under stress plays a crucial role in the consolidation of immobility behavior 25 . Transcription factor jun B is a part of the inducible transcription factor complex AP-1, which is quickly activated during gravity alterations and regulates the formation of primary osteoblasts 26 . Bile salt export pump (ABCB11) functions in bile acid transport and is a susceptive factor in hepatocytes injury 27 , and, similar to the results observed here, it was reduced after heat stress during a previous study on rats 28 .…”

Modification of growth anisotropy and cortical microtubule dynamics in Arabidopsis hypocotyls grown under microgravity conditions in space

“…The interior depth of the chamber was reduced by tightening the screw on the chamber. And then, the chamber was set on a fluorescence microscope (DMI6000B; Leica Microsystems, Wetzlar, Germany) equipped with filter sets for detecting GFP (L5; Leica Microsystems) partially modified to fit the space environment (Chatani et al ). Microscopic operations were controlled from ground by commanding.…”

Hypergravity induces vertebrae and otolith deformation in medaka fish

“…A study of bone metabolism under a microgravity environment in space for a period of approximately 2 months showed results indicating osteoclast activation in these fish (Chatani et al 2015). Furthermore, an investigation of medaka reared for a relatively short term in a space environment showed changes in gene expression levels (Chatani et al 2016). These results indicate that medaka is a suitable animal model for gravity experiments.…”