Open AccessPorphyromonas gingivalis invades human trophoblasts and inhibits proliferation by inducing G1 arrest and apoptosis
Author(s) -
Inaba Hiroaki,
Kuboniwa Masae,
Bainbridge Brian,
Yilmaz Özlem,
Katz Joseph,
Shiverick Kathleen T.,
Amano Atsuo,
Lamont Richard J.
Publication year - 2009
Publication title -
cellular microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.542
H-Index - 138
eISSN - 1462-5822
pISSN - 1462-5814
DOI - 10.1111/j.1462-5822.2009.01344.x
Subject(s) - porphyromonas gingivalis , apoptosis , biology , cyclin dependent kinase , downregulation and upregulation , cell cycle checkpoint , cdk inhibitor , microbiology and biotechnology , caspase , cell cycle , cancer research , immunology , programmed cell death , biochemistry , genetics , bacteria , gene
Summary Porphyromonas gingivalis is an oral pathogen that is also associated with serious systemic conditions such as preterm delivery. Here we investigated the interaction between P. gingivalis and a cell line of extravillous trophoblasts (HTR‐8) derived from the human placenta. P. gingivalis internalized within HTR‐8 cells and inhibited proliferation through induction of arrest in the G1 phase of the cell cycle. G1 arrest was associated with decreased expression of cyclin D and of CDKs 2, 4 and 6. In addition, levels of CDK inhibitors p15, p16, p18 and p21 were increased following P. gingivalis infection. The amount of Rb was diminished by P. gingivalis, and transient overexpression of Rb, with concomitant upregulation of phospho‐Rb, relieved P. gingivalis ‐induced G1 arrest. HTR‐8 cells halted in the G1 phase became apoptotic, and apoptosis was accompanied by an increase in the ratio of Bax/Bcl‐2 and increased activity of caspases 3, 7 and 9. HTR‐8 cells infected with P. gingivalis also exhibited a sustained activation of ERK1/2, and knock‐down of ERK1/2 activity with siRNA abrogated both G1 arrest and apoptosis. Thus, P. gingivalis can invade placental trophoblasts and induce G1 arrest and apoptosis through pathways involving ERK1/2 and its downstream effectors, properties that provide a mechanistic basis for pathogenicity in complications of pregnancy.