Aggregatibacter actinomycetemcomitans Cytolethal Distending Toxin-Induces Cell Cycle Arrest in a Glycogen Synthase Kinase (GSK)-3-Dependent Manner in Oral Keratinocytes

• Published in: International journal of molecular sciences 2022-10, Vol.23 (19), p.11831
• Main Authors: Shenker, Bruce J, Walker, Lisa P, Zekavat, Ali, Korostoff, Jonathon, Boesze-Battaglia, Kathleen
• Format: Article
• Language: English
• Subjects: Aggregatibacter actinomycetemcomitans; Aggressive Periodontitis; Apoptosis; Bacterial Toxins; Campylobacter; CDC2 Protein Kinase - metabolism; Cell activation; Cell Cycle; cell cycle arrest; Cell Cycle Checkpoints; Cell Line, Tumor; Cell lines; Cyclin-dependent kinases; Cytolethal distending toxin; DNA damage; DNA damage response; Epithelial cells; Epithelium; G2 Phase Cell Cycle Checkpoints; Glycogen; Glycogen synthase kinase 3; Glycogen Synthase Kinase 3 - metabolism; Glycogen Synthase Kinase 3 beta - metabolism; Glycogens; GSK3; Humans; Keratinocytes; Kinases; Lipids; Lymphocytes; Pathogenesis; Pathogens; Periodontitis; Phosphatase; Phosphatidylinositols - metabolism; Phosphoric Monoester Hydrolases - metabolism; Phosphorylation; Toxicity; Toxins; Whooping cough
• ISSN: 1422-0067; 1661-6596; 1422-0067
• DOI: 10.3390/ijms231911831

Cytolethal distending toxins (Cdt) are produced by a diverse group of pathogens. One Cdt-producing organism, , plays a critical role in the pathogenesis of a unique form of periodontitis, formerly referred to as localized aggressive periodontitis. The active Cdt subunit, CdtB, is a potent phosphatidylinositol (PI) 3,4,5-triphosphate phosphatase capable of inducing PI-3-kinase signaling blockade, a requisite for Cdt-induced toxicity in lymphocytes. In this study, we extended our observations to include the oral keratinocyte response to Cdt using cell lines and primary gingival keratinocytes. All three exhibited G2/M arrest when exposed to Cdt toxin within 24 h. Toxin-treated cells exhibited reduced levels of pAkt and pGSK3β within 6 h. Pre-treatment with GSK3β kinase inhibitors, LY2090314, CHIR99021 and Tideglusib, abrogated Cdt-induced G2/M arrest. None of the oral epithelial cells exhibited evidence of apoptosis. Cells remained arrested in the G2/M phase for at least 72 h without evidence of DNA damage response activation (H2AX phosphorylation). Cdt-treated cells displayed increased phosphorylation of the cyclin dependent kinase 1 (CDK1); moreover, the GSK3 inhibitors blocked this increase and reduced total CDK1 levels. This study further clarifies the potential mechanism(s) contributing to Cdt toxicity and toxin-mediated pathogenesis.