Table 1.
Expression of circRNAs in PDL (and cells) and gingival tissues.
| Reference | circRNA Name (Gene Name), Genome Location and Length | circRNA Target or Pathway | CircRNA Detection Method |
Cell (Tissue) Details | Key Findings |
|---|---|---|---|---|---|
| Yu et al. 2021 [37] | circMAP3K11 (MAP3K11) | miR-511 | RT-qPCR10 | PDL tissues from 10 healthy and 20 periodontitis cases. hPDLSCs from healthy donors. Donor age—unclear. Passage 3. |
Higher expression levels of circMAP3K11 and TLR4, and lower expression levels of miR-511-3p were found in periodontitis affected PDL tissues, compared to healthy controls. circMAP3K11 enhanced hPDLSCs proliferation, migration and osteogenic differentiation, and reduced the apoptosis of hPDLSCs in vitro through a circMAP3K11/ miR-511-3p/TLR4 axis. In vivo—silencing circMAP3K11 can prevent periodontitis development in mice, with decreased cell proliferation and increased apoptosis. |
| Zheng et al. 2021. [38] | hsa_circ_0003489 (circCDK8) chr13:26974589-26975761; 1172 bp | mTOR signalling pathway | RT-qPCR | PDL tissues from 6 healthy and 6 mild/moderate chronic periodontitis patients hPDLSCs; Healthy PDL tissues (third molars); Passage 3 to 5. |
CircCDK8 and HIF-1α were increased in PDL tissues from periodontitis patients. Overexpression of CircCDK8 decreased osteogenic differentiation of hPDLSCs through the mTOR pathway under hypoxia. |
| Wang et al. 2019. [39] | hsa_circ_0001946; CDR1as (or CiRS-7) chrX:139865339-139866824; 1485 bp |
miR-7 ERK/MAPK signal pathway |
RT-qPCR | PDL tissue from 10 periodontitis and 11 healthy cases. hPDLSCs from healthy teeth and chronic periodontitis tissue; passage 3. Donor age 30–40 yrs. |
circCDR1as was significantly downregulated in PDL tissues from periodontitis patients. circRNA CDR1as inhibited hPDLSCs proliferation through the miR-7 and ERK/MAPK pathway |
| Wang et al. 2021. [40] | circ_0081572 (GRHL2) chr8:102564942-102571040; 6098 bp |
miR-378h | RT-qPCR | Gingival tissues from 21 healthy and 21 periodontitis cases, Human periodontal ligament cells (hPDLCs). Unclear donor age and cell passage number. |
Circ_0081572 was downregulated in the gingival tissues of periodontitis, compared to healthy gingival tissues. Overexpression of circ_0081572 could alleviate LPS-induced PDLCs injury via circ_0081572/miR-378h/RORA axis. |
| Li et al. 2019. [41] | hsa_circ_0062491 chr22:23063339-23180200; 116861 bp |
miR-584 | RNA sequencing RT-qPCR |
Gingival tissues from 4 healthy and 4 chronic periodontitis cases. THP1 cells treated with P. gingivalis. |
1, 304 circRNAs were significantly differentially expressed in the gingival tissues of periodontitis patients (n = 4). Decreased circ_0062491 and increased circ_0095812 found in periodontitis-gingival tissues compared to healthy tissues (n = 30) using RT-qPCR. Circ_0062491 function as a miR-584 sponge in THP1 cells. |
Abbreviations: MAP3K11: Mitogen-activated protein kinase kinase kinase 11; CDK8: Cyclin-Dependent Kinase 8; CDR1as: Cerebellar degeneration-related protein 1 antisense RNA;GRHL2: grainyhead like transcription factor 2; TLR4: Toll-like receptor 4; HIF-1α: Hypoxia-inducible factor 1-alpha; mTOR: The mechanistic target of rapamycin; ERK: extracellular-signal-regulated kinase; RORA: RAR-related orphan receptor alpha; and THP1: human acute monocytic leukemia cell line.