Objective To investigate the effects of RCCS simulated microgravity on the metabolism of the human keratinocyte cell line HaCaT. Methods The rotary cell culture system (RCCS) was used to simulate the microgravity environment, and HaCaT cells were cultured in vitro and divided randomly into simulated microgravity group (SMG) and normal gravity group (NG). The two group HaCaT cells were collected respectively after 1 d, 2 d and 3 d culture, and the samples were analyzed by LC/MS metabolomics. The

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... differential metabolites between the SMG and NG cells were identified with partial least squares discriminant analysis ((O)PLS-DA), and the data were input into the KEGG database for the construction and functional analysis of metabolic pathways. Results Comparing to NG cells, after 1 d culture, there were 74 different metabolites in SMG cells, among which 16 were up-regulated and 58 were down-regulated; after 2 d culture, there were 89 different metabolites, among which 15 were up-regulated and 74 down-regulated; after 3d culture, there were 100 different metabolites, of which 23 were up-regulated and 77 were down-regulated. The differentially expressed 49 metabolites (VIP>1 and P<0. 05) after 3 d were set as target metabolites, within which the sphingosine, glutamate, and docosapentaenoic acid were down-regulated, and dehydrated sorbitol was up-regulated. KEGG analysis indicated that the metabolic pathways involved were amino acid metabolism, lipid metabolism, cell proliferation and apoptosis, substance transport, catabolism, and signal transduction. Conclusion RCCS simulated microgravity may have significant impacts on keratinocyte metabolism mainly involving metabolites such as sphingolipids and glutamate as well as the related signaling pathways. DOI: 10.11855/j.issn.0577-7402.2019.09.04