Angiopoietin-like 4 production upon treatment with hypoxia and L-mimosine in periodontal fibroblasts.

Abstract

BACKGROUND AND OBJECTIVE:

A key factor in the modulation of angiogenesis as well as in bone resorption is angiopoietin-like 4. However, the role of angiopoietin-like 4 in periodontal tissue is unknown. Here, we hypothesized that hypoxia and the hypoxia mimetic agent L-mimosine can induce the production of angiopoietin-like 4 in periodontal fibroblasts.

METHODS:

Human periodontal ligament fibroblasts (PDLF) were cultured in monolayer and spheroid cultures. The cultures were incubated in the presence of hypoxia or L-mimosine. Angiopoietin-like 4 mRNA and protein levels were measured by qPCR and ELISA, respectively. Also, the impact of Lipopolysaccharides of E. coli and P. gingivalis, interleukin (IL)-1β and tumor necrosis factor (TNF)α was evaluated. Furthermore, we tested dependency on hypoxia-inducible factor (HIF)-1 activity by Western blotting for HIF-1 and inhibitor studies with echinomycin. Potential autocrine effects were assessed by exposure of PDLF to recombinant angiopoietin-like 4 in full length, C-terminal and N-terminal fragments. The impact on viability, DNA synthesis, alkaline phosphatase, and matrix mineralization was evaluated.

RESULTS:

Both hypoxia and L-mimosine elevated angiopoietin-like 4 mRNA and protein levels in monolayer cultures of PDLF. HIF-1 was elevated after both hypoxia and L-mimosine treatment. LPS, IL-1β, and TNFα did not modulate angiopoietin-like 4 levels significantly. Addition of echinomycin in the cultures inhibited the production of angiopoietin-like 4. In spheroid cultures of PDLF, the increase did not reach the level of significance at mRNA and protein levels. Angiopoietin-like 4 in full length, C-terminal, and N-terminal fragments did not modulate viability, DNA synthesis, alkaline phosphatase, and matrix mineralization.

CONCLUSION:

Overall, we found that hypoxia and the hypoxia mimetic agent L-mimosine can stimulate angiopoietin-like 4 production in monolayer cultures of PDLF. This increase depends on HIF-1 activity. Future studies will reveal how the modulation of angiopoietin-like 4 in the periodontium contributes to periodontal disease and regeneration.

• Authors: Klara Janjić, Alwina Schellner, Alexander Engenhart, Kurt Kernstock, Barbara Schädl, Andreas Moritz, Hermann Agis
• Journal: Journal of periodontal research (J Periodontal Res) Vol. 54 Issue 5 Pg. 489-498 (Oct 2019) ISSN: 1600-0765 [Electronic] United States
• PMID: 30891777 (Publication Type: Journal Article)
• Copyright: © 2019 The Authors. Journal of Periodontal Research Published by John Wiley & Sons Ltd.

Chemical References

• Angiopoietin-Like Protein 4
• Angiopoietins
• Hypoxia-Inducible Factor 1, alpha Subunit
• Mimosine

Topics

• Angiopoietin-Like Protein 4 (metabolism)
• Angiopoietins
• Cells, Cultured
• Escherichia coli
• Fibroblasts
• Humans
• Hypoxia
• Hypoxia-Inducible Factor 1, alpha Subunit (metabolism)
• Mimosine (pharmacology)
• Periodontal Ligament (metabolism)