title: Nicotine-induced expression of low-density lipoprotein receptor in oral epithelial cells.
abstract: BACKGROUND
  Nicotine use is one of the most important risk factors for the development of cardiovascular and periodontal diseases. Numerous reports have suggested the possible contribution of disturbed lipid metabolism for the development of both disease groups. Despite these observations, little is known about the relationship between tobacco smoking and the development of these diseases. Our previous microarray data revealed that nicotine induced low-density lipoprotein receptor (LDLR) expression in oral epithelial cells (OECs). The aim of the present study was to confirm nicotine-mediated LDLR induction and to elucidate the signaling mechanisms leading to the augmented expression of LDLR in OECs.
  
  
  RESULTS
  LDLR and nicotinic acetylcholine receptor (nAChR) subunit expression was detected by real-time PCR. The production of LDLR was demonstrated by immunofluorescence staining. nAChR-mediated LDLR induction was examined by pre-incubation of the cells with its specific inhibitor, α-bungarotoxin (α-BTX). The functional importance of transcription factor specific protein 1 (Sp1) was examined by luciferase assay, mithramycin pre-incubation or by small interfering RNA (siRNA) transfection. The specific binding of Sp1 to R3 region of LDLR 5'-untranslated region was demonstrated with electrophoretic mobility shift assay (EMSA) and streptavidin-agarose precipitation assay followed by western blotting. The results confirmed that nicotine induced LDLR expression at the transcriptional level. Nicotine was sensed by nAChR and the signal was transduced by Sp1 which bound to the R3 region of LDLR gene. Augmented production of LDLR in the gingival epithelial cells was further demonstrated by immunofluorescence staining using the gingival tissues obtained from the smoking patients.
  
  
  CONCLUSIONS
  Taken together, the results suggested that nicotine might contribute to the development of both cardiovascular and periodontal diseases by inducing the LDLR in OECs thereby disturbing lipid metabolism.
authors.affiliation: Division of Applied Oral Sciences, Nihon University Graduate School of Dentistry, Tokyo, Japan.
authors.forename: Satoshi
authors.initials: S
authors.lastname: Ito
authors.affiliation: Division of Applied Oral Sciences, Nihon University Graduate School of Dentistry, Tokyo, Japan.
authors.forename: Takahiro
authors.initials: T
authors.lastname: Gojoubori
authors.affiliation: Division of Applied Oral Sciences, Nihon University Graduate School of Dentistry, Tokyo, Japan.
authors.forename: Kou
authors.initials: K
authors.lastname: Tsunoda
authors.affiliation: Department of Biochemistry, Nihon University School of Dentistry, Tokyo, Japan ; Division of Functional Morphology, Nihon University School of Dentistry, Tokyo, Japan.
authors.forename: Yoko
authors.initials: Y
authors.lastname: Yamaguchi
authors.affiliation: Department of Pathology, Nihon University School of Dentistry, Tokyo, Japan ; Division of Immunology and Pathobiology, Nihon University School of Dentistry, Tokyo, Japan.
authors.forename: Masatake
authors.initials: M
authors.lastname: Asano
authors.affiliation: Department of Periodontology, Nihon University School of Dentistry, Tokyo, Japan.
authors.forename: Eiji
authors.initials: E
authors.lastname: Goke
authors.affiliation: Department of Periodontology, Nihon University School of Dentistry, Tokyo, Japan ; Division of Advanced Dental Treatment, Nihon University School of Dentistry, Tokyo, Japan.
authors.forename: Ryosuke
authors.initials: R
authors.lastname: Koshi
authors.affiliation: Department of Periodontology, Nihon University School of Dentistry, Tokyo, Japan ; Division of Advanced Dental Treatment, Nihon University School of Dentistry, Tokyo, Japan.
authors.forename: Naoyuki
authors.initials: N
authors.lastname: Sugano
authors.affiliation: Department of Periodontology, Nihon University School of Dentistry, Tokyo, Japan ; Division of Advanced Dental Treatment, Nihon University School of Dentistry, Tokyo, Japan.
authors.forename: Naoto
authors.initials: N
authors.lastname: Yoshinuma
authors.affiliation: Department of Pathology, Nihon University School of Dentistry, Tokyo, Japan ; Division of Immunology and Pathobiology, Nihon University School of Dentistry, Tokyo, Japan.
authors.forename: Kazuo
authors.initials: K
authors.lastname: Komiyama
authors.affiliation: Nihon University School of Dentistry, Tokyo, Japan.
authors.forename: Koichi
authors.initials: K
authors.lastname: Ito
mesh_terms: D000328:Adult; D000368:Aged; D045744:Cell Line, Tumor; D004305:Dose-Response Relationship, Drug; D004847:Epithelial Cells / Q000187:drug effects* / Q000378:metabolism; D005260:Female; D006801:Humans; D050356:Lipid Metabolism / Q000187:drug effects / Q000235:genetics; D008297:Male; D008875:Middle Aged; D009061:Mouth Mucosa / Q000187:drug effects* / Q000378:metabolism; D009538:Nicotine / Q000494:pharmacology*; D011973:Receptors, LDL / Q000235:genetics* / Q000378:metabolism; D015854:Up-Regulation / Q000187:drug effects / Q000235:genetics
chemical_list: D011973:Receptors, LDL; D009538:Nicotine