Guangdong Province Key Laboratory of Stomatology

Lingyuan, China

Guangdong Province Key Laboratory of Stomatology

Lingyuan, China
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Cai Y.,Sun Yat Sen University | Cai Y.,Guangdong Province Key Laboratory of Stomatology | Cai Y.,VU University Amsterdam | Liao Y.,VU University Amsterdam | And 10 more authors.
Frontiers in Microbiology | Year: 2017

The cariogenic bacterium Streptococcus mutans can develop stable resistance to fluoride through chromosomal mutations in vitro. Fluoride-resistant S. mutans has seldom been isolated in clinical settings, despite the wide application of fluoride in oralcare products. One explanation is that the fluoride-resistant S. mutans strains have decreased fitness. However, so far, there has been no conclusive evidence to support this idea. The aim of this study was to investigate the fitness cost of 48-h biofilms of two fluoride-resistant S. mutans strains, UF35 and UA159-FR (UAFR), using the wild-type fluoride-sensitive strain UA159 as a reference. The engineered UF35 strain contains one point mutation, whereas UAFR, selected from NaF-containing agar plates, has multiple chromosomal mutations. All biofilms were formed for 48 h under a constantly neutral pH or a pH-cycling (8 h of neutral pH and 16 h of pH 5.5) condition in the absence of fluoride. The biomass of the biofilms was quantified with a crystal violet assay. The biofilms were also treated with chlorhexidine or solutions at pH 3.0, after which their lactic acid production was quantified. Compared to the UF35 and UA159 biofilms, the biomass of UAFR biofilms was two–four fold higher, and the UAFR biofilms were more resistant to chlorhexidine and low pH in terms of lactic acid production. No difference in biomass and lactic acid production was detected between UF35 and UA159 biofilms. The fluoride resistance of UAFR and UF35 strains in biofilms was further confirmed by treating the biofilms with NaF solutions. The level of NaF resistance of the three biofilms is generally ranked as follows: UAFR > UF35 > UA159. In conclusion, there is indeed a fitness consequence in UAFR, but surprisingly, this fluoride-resistant strain performs better than UF35 and UA159 under the described conditions. In addition, UF35 did not display a reduced fitness; it performed as well as the wild-type fluoride-sensitive strain. Copyright © 2017 Cai, Liao, Brandt, Wei, Liu, Crielaard, Van Loveren and Deng


Liu L.,Guangdong Province Key Laboratory of Stomatology | Wu L.,Guangdong Province Key Laboratory of Stomatology | Wei X.,Guangdong Province Key Laboratory of Stomatology | Ling J.,Guangdong Province Key Laboratory of Stomatology
Stem Cells and Development | Year: 2015

Octamer-binding transcription factor 4A (Oct4A), one of the three spliced variants of the class V of POU transcription factor family, is mainly expressed in the nucleus of undifferentiated cells and serves as the key regulator for the maintenance of pluripotency and self-renewal. However, its specific role in regulating pluripotency and multilineage differentiation potential of dental pulp cells (DPCs) remains unknown. To explore the effect of Oct4A on pluripotency and multilineage differentiation capability of DPCs, expression of Oct4A in human dental pulp tissue and pluripotent markers Oct4A, Sox2, c-Myc, Nanog, and Klf4 in DPCs with prolonged in vitro culture were examined by immunohistochemistry and immunofluorescent staining. Oct4A transfection rate in DPCs with lentivirus was evaluated by real-time polymerase chain reaction (PCR) and western blot. Cell proliferation, multilineage differentiation, and the expression of Oct4B1, Sox2, Nanog, Klf4, c-Myc, and Utf1 in DPCs after Oct4A transfection were detected by cell counting kit-8, Alizarin red/Oil red O staining, immunofluorescent staining, alkaline phosphatase analysis, and real-time PCR. We demonstrated that Oct4A was mainly expressed in the nucleus of odontoblasts in dental pulp tissue. Oct4A, Sox2, c-Myc, Nanog, and Klf4 were primarily located in the nucleus of DPCs at early passage (passage 1) and translocated to cytoplasm at late passage (passage 7). In DPCs with Oct4A overexpression, Oct4A, Oct4B1, Sox2, Nanog, Klf4, c-Myc, and Utf1 were significantly upregulated (p<0.05) and the cell proliferation (p<0.05), odontogenic and adipogenic differentiation were significantly enhanced. Taken together, Oct4A plays a critical role in regulation of cell proliferation, pluripotency, and multilineage differentiation potential of DPCs. © Copyright 2015, Mary Ann Liebert, Inc. 2015.

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