Hepatic Stellate Cell Selective Disruption of Dynamin-2 GTPase Increases Murine Fibrogenesis through Up-Regulation of Sphingosine-1 Phosphate–Induced Cell Migration

Ruisi Wang, Qian Ding, Thiago M. De Assuncao, Taofic Mounajjed, Jessica Maiers, Changwei Dou, Sheng Cao, Usman Yaqoob, Robert C Huebert, Vijay Shah

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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/fl mice 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/fl mice 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.

Original languageEnglish (US)
Pages (from-to)134-145
Number of pages12
JournalAmerican Journal of Pathology
Volume187
Issue number1
DOIs
StatePublished - Jan 1 2017

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Dynamin II
Hepatic Stellate Cells
Sphingosine
GTP Phosphohydrolases
Cell Movement
Up-Regulation
Receptor Protein-Tyrosine Kinases
Endocytosis
Fibrosis
Liver
Point Mutation
Liver Cirrhosis
Alanine
Lysine
Phosphorylation
Messenger RNA
sphingosine kinase
Wounds and Injuries
Enzymes

ASJC Scopus subject areas

  • Pathology and Forensic Medicine

Cite this

Hepatic Stellate Cell Selective Disruption of Dynamin-2 GTPase Increases Murine Fibrogenesis through Up-Regulation of Sphingosine-1 Phosphate–Induced Cell Migration. / Wang, Ruisi; Ding, Qian; De Assuncao, Thiago M.; Mounajjed, Taofic; Maiers, Jessica; Dou, Changwei; Cao, Sheng; Yaqoob, Usman; Huebert, Robert C; Shah, Vijay.

In: American Journal of Pathology, Vol. 187, No. 1, 01.01.2017, p. 134-145.

Research output: Contribution to journalArticle

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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/fl mice 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/fl mice 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.",
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T1 - Hepatic Stellate Cell Selective Disruption of Dynamin-2 GTPase Increases Murine Fibrogenesis through Up-Regulation of Sphingosine-1 Phosphate–Induced Cell Migration

AU - Wang, Ruisi

AU - Ding, Qian

AU - De Assuncao, Thiago M.

AU - Mounajjed, Taofic

AU - Maiers, Jessica

AU - Dou, Changwei

AU - Cao, Sheng

AU - Yaqoob, Usman

AU - Huebert, Robert C

AU - Shah, Vijay

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