title: Conjugated bile acids activate the sphingosine-1-phosphate receptor 2 in primary rodent hepatocytes.
abstract: Bile acids have been shown to be important regulatory molecules for cells in the liver and gastrointestinal tract. They can activate various cell signaling pathways including extracellular regulated kinase (ERK)1/2 and protein kinase B (AKT) as well as the G-protein-coupled receptor (GPCR) membrane-type bile acid receptor (TGR5/M-BAR). Activation of the ERK1/2 and AKT signaling pathways by conjugated bile acids has been reported to be sensitive to pertussis toxin (PTX) and dominant-negative Gα(i) in primary rodent hepatocytes. However, the GPCRs responsible for activation of these pathways have not been identified. Screening GPCRs in the lipid-activated phylogenetic family (expressed in HEK293 cells) identified sphingosine-1-phosphate receptor 2 (S1P(2) ) as being activated by taurocholate (TCA). TCA, taurodeoxycholic acid (TDCA), tauroursodeoxycholic acid (TUDCA), glycocholic acid (GCA), glycodeoxycholic acid (GDCA), and S1P-induced activation of ERK1/2 and AKT were significantly inhibited by JTE-013, a S1P(2) antagonist, in primary rat hepatocytes. JTE-013 significantly inhibited hepatic ERK1/2 and AKT activation as well as short heterodimeric partner (SHP) mRNA induction by TCA in the chronic bile fistula rat. Knockdown of the expression of S1P(2) by a recombinant lentivirus encoding S1P(2) shRNA markedly inhibited the activation of ERK1/2 and AKT by TCA and S1P in rat primary hepatocytes. Primary hepatocytes prepared from S1P(2) knock out (S1P(2) (-/-) ) mice were significantly blunted in the activation of the ERK1/2 and AKT pathways by TCA. Structural modeling of the S1P receptors indicated that only S1P(2) can accommodate TCA binding. In summary, all these data support the hypothesis that conjugated bile acids activate the ERK1/2 and AKT signaling pathways primarily through S1P(2) in primary rodent hepatocytes.
authors.affiliation: Microbiology and Immunology, Virginia Commonwealth University, Richmond, VA 23298-0678, USA.
authors.forename: Elaine
authors.initials: E
authors.lastname: Studer
authors.forename: Xiqiao
authors.initials: X
authors.lastname: Zhou
authors.forename: Renping
authors.initials: R
authors.lastname: Zhao
authors.forename: Yun
authors.initials: Y
authors.lastname: Wang
authors.forename: Kazuaki
authors.initials: K
authors.lastname: Takabe
authors.forename: Masayuki
authors.initials: M
authors.lastname: Nagahashi
authors.forename: William M
authors.initials: WM
authors.lastname: Pandak
authors.forename: Paul
authors.initials: P
authors.lastname: Dent
authors.forename: Sarah
authors.initials: S
authors.lastname: Spiegel
authors.forename: Ruihua
authors.initials: R
authors.lastname: Shi
authors.forename: Weiren
authors.initials: W
authors.lastname: Xu
authors.forename: Xuyuan
authors.initials: X
authors.lastname: Liu
authors.forename: Pat
authors.initials: P
authors.lastname: Bohdan
authors.forename: Luyong
authors.initials: L
authors.lastname: Zhang
authors.forename: Huiping
authors.initials: H
authors.lastname: Zhou
authors.forename: Phillip B
authors.initials: PB
authors.lastname: Hylemon
mesh_terms: D000818:Animals; D001647:Bile Acids and Salts / Q000378:metabolism* / Q000494:pharmacology; D001658:Biliary Fistula / Q000378:metabolism* / Q000473:pathology; D004195:Disease Models, Animal; D048049:Extracellular Signal-Regulated MAP Kinases / Q000378:metabolism; D057809:HEK293 Cells; D022781:Hepatocytes / Q000166:cytology / Q000378:metabolism*; D006801:Humans; D008297:Male; D051379:Mice; D018345:Mice, Knockout; D061251:Primary Cell Culture; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism; D011720:Pyrazoles / Q000494:pharmacology; D011725:Pyridines / Q000494:pharmacology; D034741:RNA, Small Interfering / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley; D043562:Receptors, G-Protein-Coupled / Q000378:metabolism; D049349:Receptors, Lysosphingolipid / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D012377:Rodentia; D000081025:Sphingosine-1-Phosphate Receptors; D013656:Taurocholic Acid / Q000378:metabolism / Q000494:pharmacology
chemical_list: D001647:Bile Acids and Salts; C471998:JTE 013; D011720:Pyrazoles; D011725:Pyridines; D034741:RNA, Small Interfering; D043562:Receptors, G-Protein-Coupled; D049349:Receptors, Lysosphingolipid; D000081025:Sphingosine-1-Phosphate Receptors; C533955:sphingosine-1-phosphate receptor-2, mouse; C570053:sphingosine-1-phosphate receptor-2, rat; D013656:Taurocholic Acid; C494920:Akt1 protein, rat; D051057:Proto-Oncogene Proteins c-akt; D048049:Extracellular Signal-Regulated MAP Kinases