The Active Subunit of the Cytolethal Distending Toxin, CdtB, Derived From Both Haemophilus ducreyi and Campylobacter jejuni Exhibits Potent Phosphatidylinositol-3,4,5-Triphosphate Phosphatase Activity
Human lymphocytes exposed to Aggregatibacter actinomycetemcomitans (Aa) cytolethal distending toxin (Cdt) undergo cell cycle arrest and apoptosis. In previous studies, we demonstrated that the active Cdt subunit, CdtB, is a potent phosphatidylinositol (PI) 3,4,5-triphosphate phosphatase. Moreover, A...
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Frontiers Media S.A.
2021-03-01
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| Series: | Frontiers in Cellular and Infection Microbiology |
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| Online Access: | https://www.frontiersin.org/articles/10.3389/fcimb.2021.664221/full |
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| author | Grace Huang Kathleen Boesze-Battaglia Lisa P. Walker Ali Zekavat Zachary P. Schaefer Steven R. Blanke Steven R. Blanke Steven R. Blanke Bruce J. Shenker |
| author_facet | Grace Huang Kathleen Boesze-Battaglia Lisa P. Walker Ali Zekavat Zachary P. Schaefer Steven R. Blanke Steven R. Blanke Steven R. Blanke Bruce J. Shenker |
| author_sort | Grace Huang |
| collection | DOAJ |
| description | Human lymphocytes exposed to Aggregatibacter actinomycetemcomitans (Aa) cytolethal distending toxin (Cdt) undergo cell cycle arrest and apoptosis. In previous studies, we demonstrated that the active Cdt subunit, CdtB, is a potent phosphatidylinositol (PI) 3,4,5-triphosphate phosphatase. Moreover, AaCdt-treated cells exhibit evidence of PI-3-kinase (PI-3K) signaling blockade characterized by reduced levels of PIP3, pAkt, and pGSK3β. We have also demonstrated that PI-3K blockade is a requisite of AaCdt-induced toxicity in lymphocytes. In this study, we extended our observations to include assessment of Cdts from Haemophilus ducreyi (HdCdt) and Campylobacter jejuni (CjCdt). We now report that the CdtB subunit from HdCdt and CjCdt, similar to that of AaCdt, exhibit potent PIP3 phosphatase activity and that Jurkat cells treated with these Cdts exhibit PI-3K signaling blockade: reduced levels of pAkt and pGSK3β. Since non-phosphorylated GSK3β is the active form of this kinase, we compared Cdts for dependence on GSK3β activity. Two GSK3β inhibitors were employed, LY2090314 and CHIR99021; both inhibitors blocked the ability of Cdts to induce cell cycle arrest. We have previously demonstrated that AaCdt induces increases in the CDK inhibitor, p21CIP1/WAF1, and, further, that this was a requisite for toxin-induced cell death via apoptosis. We now demonstrate that HdCdt and CjCdt also share this requirement. It is also noteworthy that p21CIP1/WAF1 was not involved in the ability of the three Cdts to induce cell cycle arrest. Finally, we demonstrate that, like AaCdt, HdCdt is dependent upon the host cell protein, cellugyrin, for its toxicity (and presumably internalization of CdtB); CjCdt was not dependent upon this protein. The implications of these findings as they relate to Cdt’s molecular mode of action are discussed. |
| first_indexed | 2024-12-14T15:20:03Z |
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| issn | 2235-2988 |
| language | English |
| last_indexed | 2024-12-14T15:20:03Z |
| publishDate | 2021-03-01 |
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| series | Frontiers in Cellular and Infection Microbiology |
| spelling | doaj.art-95d2a77b939d4cecaecc0d9e6e8b8f612022-12-21T22:56:12ZengFrontiers Media S.A.Frontiers in Cellular and Infection Microbiology2235-29882021-03-011110.3389/fcimb.2021.664221664221The Active Subunit of the Cytolethal Distending Toxin, CdtB, Derived From Both Haemophilus ducreyi and Campylobacter jejuni Exhibits Potent Phosphatidylinositol-3,4,5-Triphosphate Phosphatase ActivityGrace Huang0Kathleen Boesze-Battaglia1Lisa P. Walker2Ali Zekavat3Zachary P. Schaefer4Steven R. Blanke5Steven R. Blanke6Steven R. Blanke7Bruce J. Shenker8Department of Basic and Translational Sciences, University of Pennsylvania School of Dental Medicine, Philadelphia, PA, United StatesDepartment of Basic and Translational Sciences, University of Pennsylvania School of Dental Medicine, Philadelphia, PA, United StatesDepartment of Basic and Translational Sciences, University of Pennsylvania School of Dental Medicine, Philadelphia, PA, United StatesDepartment of Basic and Translational Sciences, University of Pennsylvania School of Dental Medicine, Philadelphia, PA, United StatesDepartment of Microbiology, University of Illinois, Urbana, IL, United StatesDepartment of Microbiology, University of Illinois, Urbana, IL, United StatesPathobiology Department, University of Illinois, Urbana, IL, United StatesBiomedical and Translational Sciences Department, University of Illinois, Urbana, IL, United StatesDepartment of Basic and Translational Sciences, University of Pennsylvania School of Dental Medicine, Philadelphia, PA, United StatesHuman lymphocytes exposed to Aggregatibacter actinomycetemcomitans (Aa) cytolethal distending toxin (Cdt) undergo cell cycle arrest and apoptosis. In previous studies, we demonstrated that the active Cdt subunit, CdtB, is a potent phosphatidylinositol (PI) 3,4,5-triphosphate phosphatase. Moreover, AaCdt-treated cells exhibit evidence of PI-3-kinase (PI-3K) signaling blockade characterized by reduced levels of PIP3, pAkt, and pGSK3β. We have also demonstrated that PI-3K blockade is a requisite of AaCdt-induced toxicity in lymphocytes. In this study, we extended our observations to include assessment of Cdts from Haemophilus ducreyi (HdCdt) and Campylobacter jejuni (CjCdt). We now report that the CdtB subunit from HdCdt and CjCdt, similar to that of AaCdt, exhibit potent PIP3 phosphatase activity and that Jurkat cells treated with these Cdts exhibit PI-3K signaling blockade: reduced levels of pAkt and pGSK3β. Since non-phosphorylated GSK3β is the active form of this kinase, we compared Cdts for dependence on GSK3β activity. Two GSK3β inhibitors were employed, LY2090314 and CHIR99021; both inhibitors blocked the ability of Cdts to induce cell cycle arrest. We have previously demonstrated that AaCdt induces increases in the CDK inhibitor, p21CIP1/WAF1, and, further, that this was a requisite for toxin-induced cell death via apoptosis. We now demonstrate that HdCdt and CjCdt also share this requirement. It is also noteworthy that p21CIP1/WAF1 was not involved in the ability of the three Cdts to induce cell cycle arrest. Finally, we demonstrate that, like AaCdt, HdCdt is dependent upon the host cell protein, cellugyrin, for its toxicity (and presumably internalization of CdtB); CjCdt was not dependent upon this protein. The implications of these findings as they relate to Cdt’s molecular mode of action are discussed.https://www.frontiersin.org/articles/10.3389/fcimb.2021.664221/fullcytolethal distending toxinhost-parasite interactionslymphocytestoxinspathogenesiscell cycle arrest |
| spellingShingle | Grace Huang Kathleen Boesze-Battaglia Lisa P. Walker Ali Zekavat Zachary P. Schaefer Steven R. Blanke Steven R. Blanke Steven R. Blanke Bruce J. Shenker The Active Subunit of the Cytolethal Distending Toxin, CdtB, Derived From Both Haemophilus ducreyi and Campylobacter jejuni Exhibits Potent Phosphatidylinositol-3,4,5-Triphosphate Phosphatase Activity Frontiers in Cellular and Infection Microbiology cytolethal distending toxin host-parasite interactions lymphocytes toxins pathogenesis cell cycle arrest |
| title | The Active Subunit of the Cytolethal Distending Toxin, CdtB, Derived From Both Haemophilus ducreyi and Campylobacter jejuni Exhibits Potent Phosphatidylinositol-3,4,5-Triphosphate Phosphatase Activity |
| title_full | The Active Subunit of the Cytolethal Distending Toxin, CdtB, Derived From Both Haemophilus ducreyi and Campylobacter jejuni Exhibits Potent Phosphatidylinositol-3,4,5-Triphosphate Phosphatase Activity |
| title_fullStr | The Active Subunit of the Cytolethal Distending Toxin, CdtB, Derived From Both Haemophilus ducreyi and Campylobacter jejuni Exhibits Potent Phosphatidylinositol-3,4,5-Triphosphate Phosphatase Activity |
| title_full_unstemmed | The Active Subunit of the Cytolethal Distending Toxin, CdtB, Derived From Both Haemophilus ducreyi and Campylobacter jejuni Exhibits Potent Phosphatidylinositol-3,4,5-Triphosphate Phosphatase Activity |
| title_short | The Active Subunit of the Cytolethal Distending Toxin, CdtB, Derived From Both Haemophilus ducreyi and Campylobacter jejuni Exhibits Potent Phosphatidylinositol-3,4,5-Triphosphate Phosphatase Activity |
| title_sort | active subunit of the cytolethal distending toxin cdtb derived from both haemophilus ducreyi and campylobacter jejuni exhibits potent phosphatidylinositol 3 4 5 triphosphate phosphatase activity |
| topic | cytolethal distending toxin host-parasite interactions lymphocytes toxins pathogenesis cell cycle arrest |
| url | https://www.frontiersin.org/articles/10.3389/fcimb.2021.664221/full |
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