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Identification of Mediators of T-cell Receptor Signaling via the Screening of Chemical Inhibitor Libraries
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Indirubin Inhibits TRAIL-Induced Activation of Death Receptor 5 in Jurkat Cells

Malaney C Young1, Nagamani Vunnam1, Robyn T Rebbeck2

  • 1Department of Biomedical Engineering, University of Minnesota, Minneapolis, MN, USA.

Natural Product Communications
|April 17, 2023
PubMed

Insights

Indirubin inhibits Death Receptor 5 (DR5) signaling by blocking key protein interactions. This discovery offers a potential therapeutic strategy for diseases driven by DR5 overactivation, such as NAFLD and neurodegeneration.

Area of Science:

  • Molecular Biology
  • Pharmacology
  • Biochemistry

Background:

  • Death Receptor 5 (DR5) is a key mediator of apoptosis, implicated in diseases like non-alcoholic fatty liver disease (NAFLD) and neurodegeneration.
  • Overactivation of DR5 signaling contributes to the pathophysiology of several life-threatening conditions, necessitating the development of DR5 antagonists.
  • Understanding DR5 conformational dynamics is crucial for identifying novel therapeutic targets.

Purpose of the Study:

  • To identify FDA-approved compounds that modulate DR5 conformational dynamics using a time-resolved FRET screening platform.
  • To investigate the specific inhibitory mechanisms of identified compounds on DR5-mediated apoptosis.
  • To evaluate the therapeutic potential of identified DR5 antagonists.

Main Methods:

  • Utilized a time-resolved fluorescence resonance energy transfer (FRET) screening platform to monitor DR5 conformational dynamics.
  • Screened a library of 2863 U.S. Food and Drug Administration (FDA)-approved compounds using high-throughput screening (HTS).
  • Assessed the effect of identified compounds on tumor necrosis factor-related apoptosis-inducing ligand (TRAIL)-induced caspase-8 activity, DR5 surface expression, TRAIL binding, Fas-associated death domain (FADD) oligomerization, and cellular FLICE-inhibitory protein (c-FLIP) expression.

Main Results:

  • Identified 13 compounds that modulated FRET between DR5 monomers.
  • Indirubin specifically inhibited TRAIL-induced caspase-8 activity without affecting DR5 surface expression or TRAIL binding.
  • Indirubin demonstrated inhibitory mechanisms by preventing FADD oligomerization and increasing c-FLIP expression.

Conclusions:

  • Indirubin exhibits previously unrecognized properties as a specific inhibitor of DR5 signaling.
  • Indirubin's mechanisms of action involve modulating FADD oligomerization and c-FLIP expression.
  • Indirubin represents a promising candidate for therapeutic development in diseases characterized by DR5 overactivation.
Keywords:
TRAILalkaloiddeath receptor 5high-throughput screeningindirubin

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