Fig 2: Silencing of circ-Grm1 suppresses the proliferation and migration of hypoxic PASMCs. (A) circ-Grm1 expression was detected via reverse transcription-quantitative PCR analysis in cells of normoxia, si-NC and si-circ-Grm1groups. (B) Cell Counting Kit-8 assay and (C) EdU assays were performed to determine the proliferative ability of PASMCs in the normoxia, si-NC and si-circ-Grm1 groups. (D) Western blot analysis was performed to measure the expression levels of cyclin A, PCNA, CDK1, Ki67, MMP-2 and MMP-9 in cells from the normoxia, si-NC and si-circ-Grm1 groups. (E) Wound healing assay was performed to determine the migratory abilities of PASMCs. Scale bar, 100 µm. The experiments were independently conducted three times, and values are shown as the mean ± SD. **P<0.01. EdU, 5-ethynyl-2-deoxyuridine; si, small interfering RNA; NC, negative control; PASMCs, pulmonary artery smooth muscle cells; circ, circular RNA; circ-Grm1, circular RNA glutamate metabotropic receptor 1; PCNA, proliferating cell nuclear antigen; OD, optical density.

Fig 3: mGluR1/5 inhibition rescues prion neurotoxicity in organotypic slice cultures.(A-B) Treatment with the mGluR5 inhibitor (MPEP) rescued neurodegeneration in tga20 RML6-treated COCS. (A) Fluorescence micrographs of tga20 COCS. RML6-induced ablation of the cerebellar granular layer (CGL) was significantly ameliorated by the mGluR5 inhibitor, MPEP. All scale bars: 500µm. (B) NeuN coverage in tga20 COCS exposed to RML6 or NBH and treated with MPEP at 21–45 days post inoculation (dpi), expressed as percentage of NBH samples. Each dot represents a pool of 4–10 slices cultured in the same well. Data points are mean ± s.d.; one-way ANOVA followed by Dunnett’s post-hoc test. (C-D) Treatment with the mGluR5 inhibitor AFQ056 (mavoglurant) also rescued neurodegeneration in tga20 RML6-treated COCS (experimental conditions as in panels A-B). (E-F) Treatment with the mGluR5 inhibitor (MPEP) rescued neurodegeneration in tga20 RML6-treated HOCS. (E) Fluorescence micrographs of tga20 HOCS, showing ablation of hippocampal neurons induced by RML6 infection (middle), that is significantly ameliorated by addition of the IC50 concentration of MPEP (36nM, 21–45 dpi, right). (F) Morphometry of the experiment shown in panel E. (G) Treatment with the mGluR1 inhibitor (YM202074) rescued neurodegeneration in tga20 RML6-treated COCS. Experimental conditions were the same as in the panels above. (H) Morphometry of the experiment shown in panel G; *: P < 0.05, **: P < 0.01, ***: P < 0.001; For (A), (C), (E) and (G) panels: Scale bar is 500µm.

Fig 4: A circ-Grm1/Grm1/Rap1 signalling axis regulates the proliferation and migration of pulmonary artery smooth muscle cells in hypoxia-induced pulmonary arterial hypertension. circ, circular RNA; circ-Grm1, circular RNA glutamate metabotropic receptor 1; FUS, FUS RNA binding protein.

Fig 5: circ-Grm1 and Grm1 are associated with the function of PASMCs by regulating the Rap1 signalling pathway. (A) Kyoto Encyclopedia of Genes and Genomes (https://www.genome.jp/kegg/pathway.html) analysis was performed using the clusterProfiler R package. (B) Expression levels of Grm1, Rap1b, p-ERK1 and ERK1 protein obtained in PASMCs from normoxia, hypoxia, oe-NC + p-NC, oe-circ-Grm1, p-Grm1 and oe-circ-Grm1 + p-Grm1 groups were detected via western blot analysis. Data are shown as the mean ± SD based on three independent experiments. **P<0.01. NC, negative control; PASMCs, pulmonary artery smooth muscle cells; circ, circular RNA; circ-Grm1, circular RNA glutamate metabotropic receptor 1; p-, pcDNA3.1; ph-, phosphorylated.