title: Hepatic Stellate Cell Selective Disruption of Dynamin-2 GTPase Increases Murine Fibrogenesis through Up-Regulation of Sphingosine-1 Phosphate-Induced Cell Migration.
abstract: Dynamin-2 (Dyn2) is implicated in endocytosis of receptor tyrosine kinases, which contribute to hepatic stellate cell (HSC) activation and liver fibrosis. A point mutation converting lysine 44 of Dyn2 to alanine (Dyn2K44A) disrupts its GTPase activity. We hypothesized that Dyn2K44A expression in HSCs would decrease HSC activation and fibrogenesis in vivo by disrupting receptor tyrosine kinase endocytosis and signaling. Dyn2K44Afl/flmice were crossed with Collagen1-Cre (Col1Cre) mice to generate offspring with HSC selective expression of Dyn2K44A (Col1Cre/Dyn2K44Afl/fl). Contrary to our hypothesis, Col1Cre/Dyn2K44Afl/flmice showed increased hepatic fibrosis in response to liver injury. To elucidate mechanisms, we conducted in vitro experiments with HSCs infected with adenoviral vectors encoding LacZ, Dyn2K44A, or Dyn2WT. HSC-expressing Dyn2K44A displayed increased mRNA and protein levels of sphingosine kinase-1 (SK1), an enzyme previously implicated in the pathogenesis of fibrosis. To study the functional effects of Dyn2K44A regulation of SK1, we examined effects of AKT signaling and migration in HSCs. Dyn2K44A promoted both AKT phosphorylation and HSC migration in an SK1-dependent manner. Genetic disruption of Dyn2 GTPase activity selectively in HSC enhances fibrogenesis, driven at least in part through up-regulation of the SK1 pathway and cell migration in HSCs.
authors.affiliation: Department of Molecular Pharmacology and Experimental Therapeutics, Mayo Clinic, Rochester, Minnesota.
authors.forename: Ruisi
authors.initials: R
authors.lastname: Wang
authors.affiliation: Department of Gastroenterology and Hepatology, Mayo Clinic, Rochester, Minnesota.
authors.forename: Qian
authors.initials: Q
authors.lastname: Ding
authors.affiliation: Department of Gastroenterology and Hepatology, Mayo Clinic, Rochester, Minnesota.
authors.forename: Thiago M
authors.initials: TM
authors.lastname: De Assuncao
authors.affiliation: Laboratory of Anatomic Pathology, Mayo Clinic, Rochester, Minnesota.
authors.forename: Taofic
authors.initials: T
authors.lastname: Mounajjed
authors.affiliation: Department of Gastroenterology and Hepatology, Mayo Clinic, Rochester, Minnesota.
authors.forename: Jessica L
authors.initials: JL
authors.lastname: Maiers
authors.affiliation: Department of Gastroenterology and Hepatology, Mayo Clinic, Rochester, Minnesota.
authors.forename: Changwei
authors.initials: C
authors.lastname: Dou
authors.affiliation: Department of Gastroenterology and Hepatology, Mayo Clinic, Rochester, Minnesota.
authors.forename: Sheng
authors.initials: S
authors.lastname: Cao
authors.affiliation: Department of Gastroenterology and Hepatology, Mayo Clinic, Rochester, Minnesota.
authors.forename: Usman
authors.initials: U
authors.lastname: Yaqoob
authors.affiliation: Department of Gastroenterology and Hepatology, Mayo Clinic, Rochester, Minnesota.
authors.forename: Robert C
authors.initials: RC
authors.lastname: Huebert
authors.affiliation: Department of Gastroenterology and Hepatology, Mayo Clinic, Rochester, Minnesota. Electronic address: shah.vijay@mayo.edu.
authors.forename: Vijay H
authors.initials: VH
authors.lastname: Shah
mesh_terms: D000818:Animals; D001652:Bile Ducts / Q000378:metabolism / Q000473:pathology; D002251:Carbon Tetrachloride; D002465:Cell Movement / Q000187:drug effects*; D024042:Collagen Type I / Q000378:metabolism; D034285:Dynamin II / Q000378:metabolism*; D055166:Hepatic Stellate Cells / Q000201:enzymology* / Q000473:pathology; D008026:Ligation; D008103:Liver Cirrhosis / Q000201:enzymology* / Q000473:pathology*; D008246:Lysophospholipids / Q000494:pharmacology*; D051379:Mice; D050505:Mutant Proteins / Q000378:metabolism; D017853:Phosphotransferases (Alcohol Group Acceptor) / Q000378:metabolism; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects; D013110:Sphingosine / Q000031:analogs & derivatives* / Q000494:pharmacology; D015854:Up-Regulation / Q000187:drug effects; D000099157:Sphingosine Kinase
chemical_list: D002251:Carbon Tetrachloride; D024042:Collagen Type I; D034285:Dynamin II; D008246:Lysophospholipids; D050505:Mutant Proteins; D017853:Phosphotransferases (Alcohol Group Acceptor); D051057:Proto-Oncogene Proteins c-akt; D013110:Sphingosine; D000099157:Sphingosine Kinase; C060506:sphingosine 1-phosphate