Gamma-linolenic acid inhibits hepatic PAI-1 expression by inhibiting p38 MAPK-dependent activator protein and mitochondria-mediated apoptosis pathway

Abstract

Fibrosis is induced by the excessive and abnormal deposition of extracellular matrix (ECM) with various growth factors in tissues. Transforming growth factor beta 1 (TGF-β1), plays a role in inducing apoptosis, modulates fibrosis, and ECM accumulation. Plasminogen activator inhibitor 1 (PAI-1) plays an important role in the development hepatic fibrosis. The overexpression of PAI-1 induces ECM accumulation, the main hallmark of chronic liver diseases. Death of hepatocytes is a characteristic feature of chronic liver disease due to various causes. The TGF-β1-mediated apoptotic pathway is regarded as a promising therapeutic target in hepatic fibrosis. Gamma-linolenic acid (GLA) is of special interest as it possesses anti-fibrosis, anti-inflammatory, and anti-cancer properties. However, the precise mechanism for GLA in chronic liver disease is not still clear. The aim of the present study was to determine whether GLA prevents hepatic PAI-1 expression and apoptosis through the inhibition of TGF-β1-mediated molecular mediators. GLA attenuated TGF-β1-stimulated PAI-1 expression, and inhibited PAI-1 promoter activity in AML12 cells. This effect was mediated by Smad3/4, the p38 pathways. We also found that GLA suppressed TGF-β1-induced apoptotic activation of the Bcl-2 family and caspase family of proteins, which resulted in the inhibition of poly-ADP-ribose polymerase 1 cleavage. GLA ameliorates the pro-fibrotic and pro-apoptotic effects of TGF-β1 in hepatocytes, suggesting GLA exerts a protective effect on hepatocytes and has a therapeutic potential for the treatment of chronic liver disease.

Suppression of Hepatic Epithelial-to-Mesenchymal Transition by Melittin via Blocking of TGFβ/Smad and MAPK-JNK Signaling Pathways

“…In TGF-β1-mediated EMT, the phosphorylated Smad3/4 complex activates the transcription of TGF-β1-mediated genes through interactions with other DNA-binding transcription factors [25]. To determine whether MEL antagonizes the effects of TGF-β1 by interfering with Smad3/4 binding to DNA, we performed an EMSA and supershift assay using a SBE-specific sequence and Smad4 Ab complexes.…”

“…Mitochondrial and cytosolic protein fractions were obtained as previously described [25]. The protein concentration was determined with a Bio-Rad Bradford kit (Bio-Rad Laboratories, Hercules, CA, USA).…”

“…According to our previous studies, DIG Gel Shift Kit (Roche, Mannheim, Germany) was performed to detect Smad binding element (SBE) DNA-binding and Smad4 antibody-binding activity, with the instructions of manufacturer [25,38]. The binding activity of Smad 3/4 in vitro and in vivo nuclear extract was confirmed by EMSA or supershift assay with a DIG-labeled oligonucleotide probe (SBE: 5′-TCG AGA GCC AGA CAA TTA GCC-3′—only sense strands are shown) and Smad4 antibody (Cell signaling).…”

Asiatic acid attenuates methamphetamine-induced neuroinflammation and neurotoxicity through blocking of NF-kB/STAT3/ERK and mitochondria-mediated apoptosis pathway

“…Cytosolic and nuclei protein fractions were obtained as described [ 32 ]. The protein concentration was determined with a Bio-Rad Bradford kit (Bio-Rad Laboratories, CA, USA).…”

“…As described in our previous studies, the DIG Gel Shift Kit (Roche, Mannheim, Germany) was used to detect NF-κB-p65- and STAT3-binding activity, with the instructions of the manufacturer [ 32 , 33 ]. The binding activity of NF-κB-p65 and STAT3 in the METH-induced cells was confirmed by EMSA or supershift assay with a DIG-labeled oligonucleotide (NF-κB: 5′-AGT TGA GGG GAC TTT CCC AGG C-3′, STAT3: 5′-CTT CAT TTC CCG TAA ATC CCT AAA GCT-3′) and NF-κB-p65 and STAT3 antibody (Cell Signaling Technology).…”