Hypoxia impairs blood–brain barrier (BBB) structure and function, causing pathophysiological changes in the context of stroke and high-altitude brain edema. Brain microvascular endothelial cells (BMECs) are major structural and functional elements of the BBB, and their exact role in hypoxia remains unknown. Here, we first deciphered the molecular events that occur in BMECs under 24 h hypoxia by whole-transcriptome sequencing assay. We found that hypoxia inhibited BMEC cell cycle progression and proliferation and downregulated minichromosome maintenance complex component 2 (Mcm2) expression. Mcm2 overexpression attenuated the inhibition of cell cycle progression and proliferation caused by hypoxia. Then, we predicted the upstream miRNAs of MCM2 through TargetScan and miRanDa and selected miR-212-3p, whose expression was significantly increased under hypoxia. Moreover, the miR-212-3p inhibitor attenuated the inhibition of cell cycle progression and cell proliferation caused by hypoxia by regulating MCM2. Taken together, these results suggest that the miR-212-3p/MCM2 axis plays an important role in BMECs under hypoxia and provide a potential target for the treatment of BBB disorder-related cerebrovascular disease.

Hypoxia leads to endothelial dysfunction and increased blood–brain barrier (BBB) permeability, promoting the incidence of diseases such as stroke and acute high-altitude illness. Brain microvascular endothelial cells (BMECs) are important structural and functional components of the BBB; however, the molecular changes that occur in BMECs during hypoxia remain unknown. We reported the molecular and functional changes in BMECs under hypoxia through whole-transcriptome sequencing, small RNA microarray, TMT quantitative proteomic, and untargeted metabolomic analyses. We found that hypoxia affected pathways such as ncRNA processing, the HIF-1 signaling pathway, the cell cycle, DNA replication, glucose metabolism, protein synthesis, and inflammation pathways. ncRNA processing was significantly downregulated. However, the levels of some miRNAs, tRNAs, tsRNAs, snoRNAs, lncRNAs, and circRNAs were significantly upregulated under hypoxia. These results suggest that ncRNAs may play an important role in oxidative stress and cellular adaptation to hypoxia, helping us understand the pathological process of BBB injury and providing potential targets for the treatment of BBB-related cerebrovascular diseases.