Gingipains disrupt F‐actin and cause osteoblast apoptosis via integrin β1

• Published in: Journal of periodontal research Vol. 53; no. 5; pp. 762 - 776
• Main Authors: Qiu, Q., Zhang, F., Wu, J., Xu, N., Liang, M.
• Format: Journal Article
• Language: English
• Published: United States Wiley Subscription Services, Inc 01.10.2018
• Subjects: Actin; Actins - metabolism; Adhesins, Bacterial - pharmacology; Animals; Annexin V; Apoptosis; Apoptosis - drug effects; Blotting, Western; Cell death; Cells, Cultured; Cysteine Endopeptidases - pharmacology; Cysteine proteinase; Cysteine Proteinase Inhibitors - pharmacology; Cytology; Dentistry; DNA nucleotidylexotransferase; Flow Cytometry; Gingipain; Gum disease; Humans; In Situ Nick-End Labeling; Integrin beta1 - metabolism; integrin β1; Mice; Microscopy, Confocal; Osteoblasts; Osteoblasts - cytology; Osteoblasts - drug effects; periodontitis; Porphyromonas gingivalis; Propidium iodide; Proteinase inhibitors; RhoA protein; Skull - cytology; Transfection; Western blotting; Porphyromonas gingivalis; integrin β1; cell death; periodontitis
• ISSN: 0022-3484; 1600-0765
• DOI: 10.1111/jre.12563

Background and Objective The aim of this study was to explore the cellular mechanisms underlying gingipain‐caused changes in cell morphology and apoptosis of osteoblasts. Material and Methods Human calvarial osteoblasts and mouse osteoblasts MC3T3‐E1 were treated with gingipain extracts from Porphyromonas gingivalis stain W83. Apoptosis was detected with annexin V and propidium iodide flow cytometry analysis or terminal deoxynucleotidyl transferase mediated dUTP nick‐end labeling staining. F‐actin was determined by immunostaining. Western blotting was used to detect protein expression. Knocking down and overexpressing approaches were used to determine the role of integrin β1. Results Osteoblasts exposed to gingipain extracts displayed increased apoptosis, accompanied by loss of F‐actin integrity and cell shrinkage. The effects of gingipain extracts were abolished by the cysteine protease inhibitor N‐tosyl‐l‐lysyl chloromethyl‐ketone. Notably, gingipain extracts resulted in reduction of integrin β1, accompanied by diminished active RhoA whereas without effect on the total RhoA. Knockdown of integrin β1 resembled those seen in gingipain‐treated osteoblasts. By contrast, the effects of gingipain extracts were abrogated by either overexpression of integrin β1 or presence of RhoA agonist CN03. Conclusion Gingipain‐induced F‐actin disruption and apoptosis are mediated by the degradation of integrin β1 and inhibition of RhoA activity, which account for osteoblast apoptosis.