Porphyromonas gingivalis gingipains cause G(1) arrest in osteoblastic/stromal cells.
BACKGROUND
The program for mammalian cell growth and division consists of four successive phases; G(1), S, G(2), and M. Porphyromonas gingivalis may manipulate the host cell cycle to benefit bacterial virulence expression, which likely causes the cell and tissue tropism observed in chronic periodontal infections. We examined P. gingivalis for its effects on cell-cycle modulation in mouse ST2 osteoblastic/stromal cells.


METHODS
Synchronized ST2 cells were infected with P. gingivalis ATCC33277 (wild-type, WT), gingipain-mutants [KDP136 (DeltargpADeltargpBDeltakgp), KDP129 (DeltargpADeltargpB), and KDP133 (Deltakgp)], and a fimbria-deficient mutant (KDP150) for 24 h, then the cell cycle was evaluated using flow cytometry. Cell-cycle-related molecule expression was examined with a microarray, as well as with quantitative real-time polymerase chain reaction and Western blotting assays.


RESULTS
Both the WT and KDP150 strains significantly inhibited cellular proliferation and arrested the cell cycle in the G(0)/G(1) phase, while the expression levels of the cell-cycle regulatory molecules cyclin D and cyclin E were also decreased. In contrast, KDP136 did not show any effects. G(1) arrest was also clearly induced by KDP129 and KDP133, with KDP129 being more effective.


CONCLUSIONS
The present findings suggest that P. gingivalis gingipains reduce cyclin expression and cause early G(1) arrest, leading to the inhibition of cellular proliferation.
Kato
T
T
Department of Oral Frontier Biology, Osaka University Graduate School of Dentistry, Suita-Osaka, Japan.
Tsuda
T
T
Inaba
H
H
Kawai
S
S
Okahashi
N
N
Shibata
Y
Y
Abiko
Y
Y
Amano
A
A
D018829:Adhesins, Bacterial / Q000502:physiology*; D000818:Animals; D001426:Bacterial Proteins / Q000502:physiology*; D001854:Bone Marrow Cells; D002460:Cell Line; D016213:Cyclins / Q000096:biosynthesis; D003546:Cysteine Endopeptidases / Q000502:physiology*; D015536:Down-Regulation; D005434:Flow Cytometry; D016193:G1 Phase; D000080867:Gingipain Cysteine Endopeptidases; D051379:Mice; D020411:Oligonucleotide Array Sequence Analysis; D010006:Osteoblasts; D016966:Porphyromonas gingivalis / Q000201:enzymology*; D017154:Stromal Cells
D018829:Adhesins, Bacterial; D001426:Bacterial Proteins; D016213:Cyclins; D000080867:Gingipain Cysteine Endopeptidases; D003546:Cysteine Endopeptidases