Increase in the sensitivity to PLX4720 through inhibition of transcription factor EB-dependent autophagy in BRAF inhibitor-resistant cells

AbstractTranscription factor EB (TFEB)-based gene therapy is a promising therapeutic strategy in treating neurodegenerative diseases by promoting autophagy/lysosome-mediated degradation and clearance of misfolded proteins that contribute to the pathogenesis of these diseases. However, recent findings have shown that TFEB has proinflammatory properties, raising the safety concerns about its clinical application. To investigate whether TFEB induces significant inflammatory responses in the brain, male C57BL/6 mice were injected with phosphate-buffered saline (PBS), adeno-associated virus serotype 8 (AAV8) vectors overexpressing mouse TFEB (pAAV8-CMV-mTFEB), or AAV8 vectors expressing green fluorescent proteins (GFPs) in the barrel cortex. The brain tissue samples were collected at 2 months after injection. Western blotting and immunofluorescence staining showed that mTFEB protein levels were significantly increased in the brain tissue samples of mice injected with mTFEB-overexpressing vectors compared with those injected with PBS or GFP-overexpressing vectors. pAAV8-CMV-mTFEB injection resulted in significant elevations in the mRNA and protein levels of lysosomal biogenesis indicators in the brain tissue samples. No significant changes were observed in the expressions of GFAP, Iba1, and proinflammation mediators in the pAAV8-CMV-mTFEB-injected brain compared with those in the control groups. Collectively, our results suggest that AAV8 successfully mediates mTFEB overexpression in the mouse brain without inducing apparent local inflammation, supporting the safety of TFEB-based gene therapy in treating neurodegenerative diseases.

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RIP3 impedes transcription factor EB to suppress autophagic degradation in septic acute kidney injury

Cell Death and Disease ◽

10.1038/s41419-021-03865-8 ◽

2021 ◽

Vol 12 (6) ◽

Author(s):

Ruizhao Li ◽

Xingchen Zhao ◽

Shu Zhang ◽

Wei Dong ◽

Li Zhang ◽

...

Keyword(s):

Acute Kidney Injury ◽

Transcription Factor ◽

Nuclear Translocation ◽

Kidney Injury ◽

Septic Acute Kidney Injury ◽

Transcription Factor Eb ◽

Autophagic Degradation ◽

Lps Treatment

AbstractAutophagy is an important renal-protective mechanism in septic acute kidney injury (AKI). Receptor interacting protein kinase 3 (RIP3) has been implicated in the renal tubular injury and renal dysfunction during septic AKI. Here we investigated the role and mechanism of RIP3 on autophagy in septic AKI. We showed an activation of RIP3, accompanied by an accumulation of the autophagosome marker LC3II and the autophagic substrate p62, in the kidneys of lipopolysaccharide (LPS)-induced septic AKI mice and LPS-treated cultured renal proximal tubular epithelial cells (PTECs). The lysosome inhibitor did not further increase the levels of LCII or p62 in LPS-treated PTECs. Moreover, inhibition of RIP3 attenuated the aberrant accumulation of LC3II and p62 under LPS treatment in vivo and in vitro. By utilizing mCherry-GFP-LC3 autophagy reporter mice in vivo and PTECs overexpression mRFP-GFP-LC3 in vitro, we observed that inhibition of RIP3 restored the formation of autolysosomes and eliminated the accumulated autophagosomes under LPS treatment. These results indicated that RIP3 impaired autophagic degradation, contributing to the accumulation of autophagosomes. Mechanistically, the nuclear translocation of transcription factor EB (TFEB), a master regulator of the lysosome and autophagy pathway, was inhibited in LPS-induced mice and LPS-treated PTECs. Inhibition of RIP3 restored the nuclear translocation of TFEB in vivo and in vitro. Co-immunoprecipitation further showed an interaction of RIP3 and TFEB in LPS-treated PTECs. Also, the expression of LAMP1 and cathepsin B, two potential target genes of TFEB involved in lysosome function, were decreased under LPS treatment in vivo and in vitro, and this decrease was rescued by inhibiting RIP3. Finally, overexpression of TFEB restored the autophagic degradation in LPS-treated PTECs. Together, the present study has identified a pivotal role of RIP3 in suppressing autophagic degradation through impeding the TFEB-lysosome pathway in septic AKI, providing potential therapeutic targets for the prevention and treatment of septic AKI.

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Contribution of transcription factor EB to adipoRon-induced inhibition of arterial smooth muscle cell proliferation and migration

AJP Cell Physiology ◽

10.1152/ajpcell.00294.2019 ◽

2019 ◽

Vol 317 (5) ◽

pp. C1034-C1047 ◽

Cited By ~ 1

Author(s):

Yun-Ting Wang ◽

Jiajie Chen ◽

Xiang Li ◽

Michihisa Umetani ◽

Yang Chen ◽

...

Keyword(s):

Cell Proliferation ◽

Transcription Factor ◽

Smooth Muscle ◽

Smooth Muscle Cell ◽

Muscle Cell ◽

Vascular Remodeling ◽

Therapeutic Effects ◽

Transcription Factor Eb ◽

And Migration ◽

Proliferation And Migration

Abnormal vascular smooth muscle cell (SMC) dedifferentiation with increased proliferation and migration during pathological vascular remodeling is associated with vascular disorders, such as atherosclerosis and in-stent restenosis. AdipoRon, a selective agonist of adiponectin receptor, has been shown to protect against vascular remodeling by preventing SMC dedifferentiation. However, the molecular mechanisms that mediate adipoRon-induced SMC differentiation are not well understood. The present study aimed to elucidate the role of transcription factor EB (TFEB), a master regulator of autophagy, in mediating adipoRon’s effect on SMCs. In cultured arterial SMCs, adipoRon dose-dependently increased TFEB activation, which is accompanied by upregulated transcription of genes involved in autophagy pathway and enhanced autophagic flux. In parallel, adipoRon suppressed serum-induced cell proliferation and caused cell cycle arrest. Moreover, adipoRon inhibited SMC migration as characterized by wound-healing retardation, F-actin reorganization, and matrix metalloproteinase-9 downregulation. These inhibitory effects of adipoRon on proliferation and migration were attenuated by TFEB gene silencing. Mechanistically, activation of TFEB by adipoRon is dependent on intracellular calcium, but it is not associated with changes in AMPK, ERK1/2, Akt, or molecular target of rapamycin complex 1 activation. Using ex vivo aortic explants, we demonstrated that adipoRon inhibited sprouts that had outgrown from aortic rings, whereas lentiviral TFEB shRNA transduction significantly reversed this effect of adipoRon on aortic rings. Taken together, our results indicate that adipoRon activates TFEB signaling that helps maintain the quiescent and differentiated status of arterial SMCs, preventing abnormal SMC dedifferentiation. This study provides novel mechanistic insights into understanding the therapeutic effects of adipoRon on TFEB signaling and pathological vascular remodeling.

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Oxidative Stress by Monoamine Oxidase-A Impairs Transcription Factor EB Activation and Autophagosome Clearance, Leading to Cardiomyocyte Necrosis and Heart Failure

Antioxidants and Redox Signaling ◽

10.1089/ars.2015.6522 ◽

2016 ◽

Vol 25 (1) ◽

pp. 10-27 ◽

Cited By ~ 41

Author(s):

Yohan Santin ◽

Pierre Sicard ◽

François Vigneron ◽

Céline Guilbeau-Frugier ◽

Marianne Dutaur ◽

...

Keyword(s):

Oxidative Stress ◽

Heart Failure ◽

Transcription Factor ◽

Monoamine Oxidase ◽

Monoamine Oxidase A ◽

Transcription Factor Eb

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Decorin-evoked paternally expressed gene 3 (PEG3) is an upstream regulator of the transcription factor EB (TFEB) in endothelial cell autophagy

Journal of Biological Chemistry ◽

10.1074/jbc.m116.769950 ◽

2017 ◽

Vol 292 (39) ◽

pp. 16211-16220 ◽

Cited By ~ 19

Author(s):

Thomas Neill ◽

Catherine Sharpe ◽

Rick T. Owens ◽

Renato V. Iozzo

Keyword(s):

Transcription Factor ◽

Endothelial Cell ◽

Upstream Regulator ◽

Transcription Factor Eb

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Deregulated FASN Expression in BRAF Inhibitor-Resistant Melanoma Cells Unveils New Targets for Drug Combinations

Cancers ◽

10.3390/cancers13092284 ◽

2021 ◽

Vol 13 (9) ◽

pp. 2284

Author(s):

Serena Stamatakos ◽

Giovanni Luca Beretta ◽

Elisabetta Vergani ◽

Matteo Dugo ◽

Cristina Corno ◽

...

Keyword(s):

Drug Resistance ◽

Metastatic Melanoma ◽

Mutant Cell ◽

Braf Inhibitor ◽

Cancer Cell Line ◽

Melanoma Cells ◽

Melanoma Progression ◽

Increased Sensitivity ◽

Resistant Cells

Metabolic changes promoting cell survival are involved in metastatic melanoma progression and in the development of drug resistance. In BRAF-inhibitor resistant melanoma cells, we explored the role of FASN, an enzyme involved in lipogenesis overexpressed in metastatic melanoma. Resistant melanoma cells displaying enhanced migratory and pro-invasive abilities increased sensitivity to the BRAF inhibitor PLX4032 upon the molecular targeting of FASN and upon treatment with the FASN inhibitor orlistat. This behavior was associated with a marked apoptosis and caspase 3/7 activation observed for the drug combination. The expression of FASN was found to be inversely associated with drug resistance in BRAF-mutant cell lines, both in a set of six resistant/sensitive matched lines and in the Cancer Cell Line Encyclopedia. A favorable drug interaction in resistant cells was also observed with U18666 A inhibiting DHCR24, which increased upon FASN targeting. The simultaneous combination of the two inhibitors showed a synergistic interaction with PLX4032 in resistant cells. In conclusion, FASN plays a role in BRAF-mutated melanoma progression, thereby creating novel therapeutic opportunities for the treatment of melanoma.

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