Nicotine-Induced Expression of Low-Density Lipoprotein Receptor in Oral Epithelial Cells

Abstract

BackgroundNicotine 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.Methods and ResultsLDLR 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. ConclusionsTaken 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.

Multi-ancestry genome-wide gene–smoking interaction study of 387,272 individuals identifies new loci associated with serum lipids

“…The biological mechanisms through which smoking influences the observed genetic associations will require further investigation, as the myriad components of cigarette smoke and their downstream consequences (including oxidative stress and inflammation) affect pathways throughout the body 44 . However, there is evidence for differential expression of PTPRZ1 15 , LPL 15 and LDLR 45 in cells exposed to an acute dose of nicotine. Also, concentrations of CETP

46.Centre for Cognitive Ageing and Cognitive EpidemiologyThe University of EdinburghEdinburghUK.

, ApoB 47 , and LPL 48 are associated with smoking status.…”

Global analysis of gene expression mediated by OX1 orexin receptor signaling in a hypothalamic cell line

“…As seen in the earlier results, the Egr family of transcription factors was again identified. Interestingly, one of the other transcription factors identified, Sp1, is a known substrate of Sgk1 [ 98 ] and has been shown to regulate the transcription of Ldlr [ 99 , 100 ], Dok7 [ 101 ], Rara [ 102 , 103 ], and Cldn4 [ 104 , 105 ].…”

Nicotine‐Mediated Ca2+‐Influx Induces IL‐8 Secretion in Oral Squamous Cell Carcinoma Cell

“…In the present study, we attempted to examine the role of Ca 2+ in nicotine‐induced IL‐8 secretion in the OSCC line Ca9‐22, which is known to express most of the nAChR subunits [Ito et al, ]. Pre‐treatment of the cells with αBtx partially abolished nicotine‐induced IL‐8 secretion by the cells.…”

“…Nicotine recognition can be achieved by nicotinic acetylcholine receptors (nAChR), which are pentameric, ligand‐gated, cation channels expressed in both neuronal and non‐neuronal cells [Lindstrom, ; Pankratov and Lalo, ]. The expression of nAChR subunits has also been reported in gingival epithelial cells [Nguyen et al, ; Arredondo et al, ; Ito et al, ]. The binding of nicotine to nAChR evokes the entry of Ca 2+ ions into the cytoplasm and raises the concentration of free Ca 2+ inside the cell [Fucile, ].…”