title: Involvement of PtdIns(4,5)P2 in the regulatory mechanism of small intestinal P-glycoprotein expression.
abstract: Previously, we reported that repeated oral administration of etoposide (ETP) activates the ezrin/radixin/moesin (ERM) scaffold proteins for P-glycoprotein (P-gp) via Ras homolog gene family member A (RhoA)/Rho-associated coiled-coil containing protein kinase (ROCK) signaling, leading to increased ileal P-gp expression. Recent studies indicate that phosphatidyl inositol 4,5-bisphosphate [PtdIns(4,5)P2] regulates the plasma-membrane localization of certain proteins, and its synthase, the type I phosphatidyl inositol 4-phosphate 5-kinase (PI4P5K), is largely controlled by RhoA/ROCK. Here, we examined whether PtdIns(4,5)P2 and PI4P5K are involved in the increased expression of ileal P-gp following the ERM activation by ETP treatment. Male ddY mice (4-week-old) were treated with ETP (10 mg/kg/day, per os, p.o.) for 5 days. Protein-expression levels were measured by either western blot or dot blot analysis and molecular interactions were assessed using immunoprecipitation assays. ETP treatment significantly increased PI4P5K, ERM, and P-gp expression in the ileal membrane. This effect was suppressed following the coadministration of ETP with rosuvastatin (a RhoA inhibitor) or fasudil (a ROCK inhibitor). Notably, the PtdIns(4,5)P2 expression in the ileal membrane, as well as both P-gp and ERM levels coimmunoprecipitated with anti-PtdIns(4,5)P2 antibody, were increased by ETP treatment. PtdIns(4,5)P2 and PI4P5K may contribute to the increase in ileal P-gp expression observed following the ETP treatment, possibly through ERM activation via the RhoA/ROCK pathway.
authors: Department of Clinical Pharmacy, School of Pharmaceutical Sciences, Kobe Gakuin University, Kobe, Japan.
authors: Takuro
authors: T
authors: Kobori
authors: Shinichi
authors: S
authors: Harada
authors: Kazuo
authors: K
authors: Nakamoto
authors: Shogo
authors: S
authors: Tokuyama
mesh_terms: D019307:1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine / Q000031:analogs & derivatives / Q000494:pharmacology; D018435:ATP Binding Cassette Transporter, Subfamily B / Q000096:biosynthesis*; D000818:Animals; D015153:Blotting, Western; D003598:Cytoskeletal Proteins / Q000378:metabolism; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005047:Etoposide / Q000493:pharmacokinetics; D005464:Fluorobenzenes / Q000494:pharmacology; D005786:Gene Expression Regulation / Q000502:physiology; D019161:Hydroxymethylglutaryl-CoA Reductase Inhibitors / Q000494:pharmacology; D007082:Ileum / Q000378:metabolism; D047468:Immunoprecipitation; D007413:Intestinal Mucosa / Q000378:metabolism; D007421:Intestine, Small / Q000378:metabolism* / Q000502:physiology; D008297:Male; D008565:Membrane Proteins / Q000378:metabolism; D053858:Metabolic Networks and Pathways; D051379:Mice; D008840:Microfilament Proteins / Q000378:metabolism; D019269:Phosphatidylinositol 4,5-Diphosphate / Q000502:physiology*; D017853:Phosphotransferases (Alcohol Group Acceptor) / Q000378:metabolism; D011743:Pyrimidines / Q000494:pharmacology; D000068718:Rosuvastatin Calcium; D013449:Sulfonamides / Q000494:pharmacology; D054460:rho-Associated Kinases / Q000378:metabolism; D020742:rhoA GTP-Binding Protein / Q000378:metabolism; D000099149:Ezrin
chemical_list: D019307:1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine; D018435:ATP Binding Cassette Transporter, Subfamily B; D003598:Cytoskeletal Proteins; D004791:Enzyme Inhibitors; D005047:Etoposide; D005464:Fluorobenzenes; D019161:Hydroxymethylglutaryl-CoA Reductase Inhibitors; D008565:Membrane Proteins; D008840:Microfilament Proteins; D019269:Phosphatidylinositol 4,5-Diphosphate; D017853:Phosphotransferases (Alcohol Group Acceptor); D011743:Pyrimidines; D000068718:Rosuvastatin Calcium; D013449:Sulfonamides; D054460:rho-Associated Kinases; D020742:rhoA GTP-Binding Protein; D000099149:Ezrin; C071058:moesin; C071776:radixin; C020077:1-phosphatidylinositol-4-phosphate 5-kinase; C515854:Rock1 protein, mouse; C049347:fasudil
keywords: ABC transporters; P-glycoprotein; absorption; efflux pumps; ileum