title: Lysophosphatidic acid upregulates connective tissue growth factor expression in osteoblasts through the GPCR/PKC and PKA pathways.
abstract: Lysophosphatidic acid (LPA) is an efficient, bioactive phospholipid involved in various biological processes. In this study, LPA-induced connective tissue growth factor (CTGF/CCN2) expression and the underlying mechanisms were investigated using the MC3T3-E1 cell line. The MC3T3-E1 cells were stimulated with an inhibitor of LPA receptors, an activator and inhibitor of protein kinase C (PKC) and protein kinase A (PKA) for indicated periods of time. RT-qPCR and western blot analyses were used to measure the expression levels of CCN2. Immunofluorescence staining was used to observe the translocation of PKC. The mRNA expression level of CCN2 was increased following stimulation of the cells with LPA; LPA transiently induced the mRNA expression of CCN2; maximum expression levels were observed 2 h following stimulation with LPA. This increase was accompanied by CCN2 protein synthesis. LPA receptor1/3 was inhibited by Ki16425, a specific inhibitor of LPA1/3; as a result, the LPA-induced increase in CCN2 expression was abrogated. LPA also induced the membrane translocation of PKC and enhanced PKC activity in the osteoblasts. Pre-treatment of the osteoblasts with staurosporine prevented the increase in CCN2 expression by induced by LPA, and the activation of PKC by phorbol 12-myristate 13-acetate (PMA) enhanced CCN2 expression, indicating that the PKC pathway is involved in the LPA-induced increase in CCN2 expression. The interference of PKA signaling also led to the induction of CCN2 expresion by LPA. These data indicate that LPA increases CCN2 expression through the activation of PKC and PKA. Thus, the regulatory functions of the PKC and PKA pathways are implicated in the LPA-induced increase in CCN2 expression.
authors.affiliation: The State Key Laboratory Breeding Base of Basic Science of Stomatology (Hubei-MOST) and Key Laboratory of Oral Biomedicine Ministry of Education, School and Hospital of Stomatology, Wuhan University, Wuhan, Hubei 430079, P.R. China.
authors.forename: Zi-Li
authors.initials: ZL
authors.lastname: Yu
authors.affiliation: The State Key Laboratory Breeding Base of Basic Science of Stomatology (Hubei-MOST) and Key Laboratory of Oral Biomedicine Ministry of Education, School and Hospital of Stomatology, Wuhan University, Wuhan, Hubei 430079, P.R. China.
authors.forename: Dian-Qi
authors.initials: DQ
authors.lastname: Li
authors.affiliation: The State Key Laboratory Breeding Base of Basic Science of Stomatology (Hubei-MOST) and Key Laboratory of Oral Biomedicine Ministry of Education, School and Hospital of Stomatology, Wuhan University, Wuhan, Hubei 430079, P.R. China.
authors.forename: Xiang-Yu
authors.initials: XY
authors.lastname: Huang
authors.affiliation: The State Key Laboratory Breeding Base of Basic Science of Stomatology (Hubei-MOST) and Key Laboratory of Oral Biomedicine Ministry of Education, School and Hospital of Stomatology, Wuhan University, Wuhan, Hubei 430079, P.R. China.
authors.forename: Xin
authors.initials: X
authors.lastname: Xing
authors.affiliation: The State Key Laboratory Breeding Base of Basic Science of Stomatology (Hubei-MOST) and Key Laboratory of Oral Biomedicine Ministry of Education, School and Hospital of Stomatology, Wuhan University, Wuhan, Hubei 430079, P.R. China.
authors.forename: Ru-Qing
authors.initials: RQ
authors.lastname: Yu
authors.affiliation: The State Key Laboratory Breeding Base of Basic Science of Stomatology (Hubei-MOST) and Key Laboratory of Oral Biomedicine Ministry of Education, School and Hospital of Stomatology, Wuhan University, Wuhan, Hubei 430079, P.R. China.
authors.forename: Zhi
authors.initials: Z
authors.lastname: Li
authors.affiliation: The State Key Laboratory Breeding Base of Basic Science of Stomatology (Hubei-MOST) and Key Laboratory of Oral Biomedicine Ministry of Education, School and Hospital of Stomatology, Wuhan University, Wuhan, Hubei 430079, P.R. China.
authors.forename: Zu-Bing
authors.initials: ZB
authors.lastname: Li
mesh_terms: D000818:Animals; D002460:Cell Line; D055513:Connective Tissue Growth Factor / Q000096:biosynthesis*; D017868:Cyclic AMP-Dependent Protein Kinases / Q000037:antagonists & inhibitors / Q000096:biosynthesis*; D005786:Gene Expression Regulation / Q000187:drug effects; D006801:Humans; D008246:Lysophospholipids / Q000008:administration & dosage*; D051379:Mice; D010006:Osteoblasts / Q000187:drug effects / Q000473:pathology; D010766:Phosphorylation; D011493:Protein Kinase C / Q000037:antagonists & inhibitors / Q000096:biosynthesis*; D047428:Protein Kinase Inhibitors / Q000008:administration & dosage; D012333:RNA, Messenger / Q000096:biosynthesis; D049368:Receptors, Lysophosphatidic Acid / Q000037:antagonists & inhibitors; D015398:Signal Transduction / Q000187:drug effects; D015533:Transcriptional Activation / Q000187:drug effects
chemical_list: C526318:CCN2 protein, mouse; D008246:Lysophospholipids; D047428:Protein Kinase Inhibitors; D012333:RNA, Messenger; D049368:Receptors, Lysophosphatidic Acid; D055513:Connective Tissue Growth Factor; D017868:Cyclic AMP-Dependent Protein Kinases; D011493:Protein Kinase C; C032881:lysophosphatidic acid