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FASEB J. 2019 Oct 26:fj201901705R. doi: 10.1096/fj.201901705R. [Epub ahead of print]

Tackling MARCKS-PIP3 circuit attenuates fibroblast activation and fibrosis progression.

Yang DC1,2,3, Li JM3, Xu J3, Oldham J1,2, Phan SH4, Last JA1,2, Wu R1,2, Chen CH3.

Author information

1
Division of Pulmonary and Critical Care Medicine, Department of Internal Medicine,, University of California-Davis, Davis, California, USA.
2
Department of Internal Medicine, Center for Comparative Respiratory Biology and Medicine, University of California-Davis, Davis, California, USA.
3
Division of Nephrology, Department of Internal Medicine, University of California-Davis, Davis, California, USA.
4
Department of Pathology, University of Michigan School of Medicine, Ann Arbor, Michigan, USA.

Abstract

Targeting activated fibroblasts, including myofibroblast differentiation, has emerged as a key therapeutic strategy in patients with idiopathic pulmonary fibrosis (IPF). However, there is no available therapy capable of selectively eradicating myofibroblasts or limiting their genesis. Through an integrative analysis of the regulator genes that are responsible for the activation of IPF fibroblasts, we noticed the phosphatidylinositol 4,5-bisphosphate (PIP2)-binding protein, myristoylated alanine-rich C-kinase substrate (MARCKS), as a potential target molecule for IPF. Herein, we have employed a 25-mer novel peptide, MARCKS phosphorylation site domain sequence (MPS), to determine if MARCKS inhibition reduces pulmonary fibrosis through the inactivation of PI3K/protein kinase B (AKT) signaling in fibroblast cells. We first observed that higher levels of MARCKS phosphorylation and the myofibroblast marker α-smooth muscle actin (α-SMA) were notably overexpressed in all tested IPF lung tissues and fibroblast cells. Treatment with the MPS peptide suppressed levels of MARCKS phosphorylation in primary IPF fibroblasts. A kinetic assay confirmed that this peptide binds to phospholipids, particularly PIP2, with a dissociation constant of 17.64 nM. As expected, a decrease of phosphatidylinositol (3,4,5)-trisphosphate pools and AKT activity occurred in MPS-treated IPF fibroblast cells. MPS peptide was demonstrated to impair cell proliferation, invasion, and migration in multiple IPF fibroblast cells in vitro as well as to reduce pulmonary fibrosis in bleomycin-treated mice in vivo. Surprisingly, we found that MPS peptide decreases α-SMA expression and synergistically interacts with nintedanib treatment in IPF fibroblasts. Our data suggest MARCKS as a druggable target in pulmonary fibrosis and also provide a promising antifibrotic agent that may lead to effective IPF treatments.-Yang, D. C., Li, J.-M., Xu, J., Oldham, J., Phan, S. H., Last, J. A., Wu, R., Chen, C.-H. Tackling MARCKS-PIP3 circuit attenuates fibroblast activation and fibrosis progression.

KEYWORDS:

AKT signaling; drug efficacy; nintedanib; phospholipids; pulmonary fibrosis

PMID:
31661644
DOI:
10.1096/fj.201901705R

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