RRC ID 61123
Author Kamio K, Azuma A, Usuki J, Matsuda K, Inomata M, Nishijima N, Itakura S, Hayashi H, Kashiwada T, Kokuho N, Atsumi K, Yamaguchi T, Fujita K, Saito Y, Abe S, Kubota K, Gemma A.
Title XPLN is modulated by HDAC inhibitors and negatively regulates SPARC expression by targeting mTORC2 in human lung fibroblasts.
Journal Pulm Pharmacol Ther
Abstract Pathogenesis of idiopathic pulmonary fibrosis (IPF) remains unclear. Secreted protein acidic and rich in cysteine (SPARC) is a matricellular protein that participates in the assembly and turnover of the extracellular matrix, whose expression is regulated by transforming growth factor (TGF)-β1 through activation of mammalian target of rapamycin complex 2 (mTORC2). Exchange factor found in platelets, leukemic, and neuronal tissues (XPLN) is an endogenous inhibitor of mTORC2. However, whether XPLN modulates SPARC expression remains unknown. Herein, we investigated the regulatory mechanisms of XPLN in human lung fibroblasts. Effect of XPLN on mTORC2 activity was evaluated by silencing XPLN in human foetal lung fibroblasts (HFL-1 cells), using small interfering RNA. SPARC expression was quantified by quantitative real-time RT-PCR and western blotting. Fibroblasts were treated with TGF-β1, histone deacetylase (HDAC) inhibitors, entinostat, or vorinostat, to assess their effects on XPLN expression. Moreover, the effect of mTORC1 inhibition on SPARC and XPLN was examined. XPLN depletion stimulated SPARC expression and Akt phosphorylation on Ser473. TGF-β1 treatment down-regulated XPLN via Smad 2/3. XPLN mRNA expression was up-regulated upon treatment with HDAC inhibitors in a concentration-dependent manner, and TGF-β1-induced SPARC expression was reversed by entinostat treatment. mTORC1 inhibition by rapamycin and Raptor depletion stimulated SPARC expression. In conclusion, this is the first study describing the involvement of XPLN in the regulation of SPARC. These findings may help uncover the regulatory mechanisms of the mTORC2-SPARC axis. The up-regulation of XPLN by HDAC inhibitors may be a novel therapeutic approach in patients with IPF.
Volume 44
Pages 61-69
Published 2017-6
DOI 10.1016/j.pupt.2017.03.003
PII S1094-5539(16)30204-8
PMID 28315487
MeSH Benzamides / pharmacology Cells, Cultured Extracellular Matrix / drug effects Extracellular Matrix / metabolism Fibroblasts / drug effects Fibroblasts / metabolism* Gene Silencing Histone Deacetylase Inhibitors / pharmacology* Humans Hydroxamic Acids / pharmacology Idiopathic Pulmonary Fibrosis / physiopathology* Lung / cytology Lung / drug effects Lung / metabolism Mechanistic Target of Rapamycin Complex 2 / metabolism Osteonectin / genetics Pyridines / pharmacology RNA, Small Interfering / administration & dosage Reverse Transcriptase Polymerase Chain Reaction Rho Guanine Nucleotide Exchange Factors / drug effects* Rho Guanine Nucleotide Exchange Factors / genetics Rho Guanine Nucleotide Exchange Factors / metabolism Transforming Growth Factor beta1 / administration & dosage Transforming Growth Factor beta1 / metabolism Up-Regulation Vorinostat
Resource
Human and Animal Cells HFL-I(RCB0521)