Angiogenin production in response to hypoxia and l‐mimosine in periodontal fibroblasts

Abstract

Background: A major mediator of angiogenesis is angiogenin, which is expressed in the early phase of healing in oral tissue engineering strategies. It is unclear how angiogenin is regulated in the periodontal tissue. The objective of this study was to reveal the regulation of angiogenin in response to hypoxia and the hypoxia mimetic agent L-mimosine in periodontal fibroblasts.Methods: Human fibroblasts of the periodontal ligament (PDLF) and the gingiva (GF) in monolayer and spheroid cultures were exposed to hypoxia or L-mimosine. The production of angiogenin was evaluated at mRNA and protein levels with reverse transcription quantitative polymerase chain reaction and enzyme-linked immunosorbent assays, respectively. Echinomycin, an inhibitor of hypoxia-inducible factor (HIF)-1 activity, was used to test the involvement of HIF-1. Results:Our data show that hypoxia and L-mimosine can increase angiogenin mRNA and protein levels in PDLF monolayer cultures. In GF monolayer cultures, we found an increase of angiogenin at the mRNA level in response to hypoxia. The increase of angiogenin can be blocked by inhibition of HIF-1 signaling via echinomycin. In PDLF and GF spheroid cultures, the impact of hypoxia and L-mimosine did not reach the level of significance. Conclusion:Hypoxia and the hypoxia mimetic agent L-mimosine can increase the production of angiogenin via HIF-1 signaling in PDLF monolayer cultures but not in spheroid cultures. GF were less sensitive to the impact of hypoxia and L-mimosine. Overall, these results suggest a link between hypoxia, HIF-1 signaling and angiogenin in the periodontium. K E Y W O R D Sbone biology, cell biology, fibroblast(s), gene regulation, growth factors, wound healing 674

Urinary Angiogenin as a Marker for Bladder Cancer: A Meta-Analysis

“…ANG contains a single-chain protein including 123 amino acids [ 30 ], with 14.4 kDa weight [ 31 ], defined through two α -helices, seven β -sheets, and three disulfide bonds. The gene encoding ANG is located on chromosome 14q11.2 [ 32 ]. ANG is the first human tumor-derived protein to develop blood vessels' growth, and it supported the Folkman's hypothesis of tumor growth is angiogenesis-dependent [ 33 , 34 ].…”

Effects of collagen membranes and bone substitute differ in periodontal ligament cell microtissues and monolayers

“…Experiments in vivo demonstrated the opposite effect where various bone substitute materials downregulated VEGF 43 as it was also the case in PDLC microtissues (Table 2, Supplementary Figure S3). It is known that ANG acts as an enhancer of angiogenesis, for example in skin when loaded onto a collagen‐chitosan scaffold 44 and that it is produced by cells from the periodontal ligament 14 . Its role in the human periodontal ligament has not been clarified yet.…”

“…In the last years, microtissue models like spheroids were established and were also produced with cells deriving from periodontal ligament 13,14 . What we know is that these periodontal ligament cell spheroids display different regeneration-associated functions 15 and characteristics 16 than periodontal ligament cell monolayers.…”

The response of gingiva monolayer, spheroid, and ex vivo tissue cultures to collagen membranes and bone substitute

“…Gene expression of markers representative for regeneration is another important criteria for a suitable cell culture system for research in tissue engineering. VEGF and ANG are pro‐angiogenic molecules which have already been extensively researched in tissue engineering (Yamada et al, 2006), (Janjić et al, 2019). In our study, VEGF and ANG mRNA production in response to culture on collagen membranes or bone substitute (Figure 4b–h) was not comparable between different cell culture models.…”