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The C-terminal transactivation domain of MITF interacts promiscuously with co-activator CBP/p300

Alexandra D Brown1, Kyle Lynch1, David N Langelaan2

  • 1Department of Biochemistry and Molecular Biology, Dalhousie University, Halifax, NS, B3H 4R2, Canada.

Scientific Reports
|September 26, 2023
PubMed

Insights

The microphthalmia-associated transcription factor (MITF) interacts with CBP/p300 co-activators via its intrinsically disordered C-terminal region. This interaction, involving specific MITF motifs, is crucial for MITF-driven gene transcription in melanocytes and melanoma.

Area of Science:

  • Molecular biology
  • Cellular biology
  • Biochemistry

Background:

  • The microphthalmia-associated transcription factor (MITF) is vital for melanocyte development and function.
  • Dysregulated MITF activity is implicated in diseases like melanoma, where it acts as an oncogene.
  • MITF recruits CREB-binding protein (CBP) and p300 co-activators to gene promoters to enhance transcription.

Purpose of the Study:

  • To characterize the molecular interactions between the MITF C-terminal transactivation domain and the co-activators CBP/p300.
  • To identify the specific regions and motifs within MITF critical for binding to CBP/p300.
  • To understand how these interactions contribute to MITF-mediated gene transcription.

Main Methods:

  • Nuclear Magnetic Resonance (NMR) spectroscopy to analyze protein structure and interactions.
  • Protein pulldown assays to confirm binding between MITF and CBP/p300.
  • Isothermal titration calorimetry (ITC) to quantify binding affinity.
  • Mutagenesis studies to identify key functional motifs in MITF.

Main Results:

  • The C-terminal region of MITF is intrinsically disordered and binds with high affinity to both TAZ1 and TAZ2 domains of CBP/p300.
  • Two conserved motifs within MITF were identified as essential for TAZ2 binding and MITF-dependent transcription.
  • The transactivation capability of the MITF C-terminal region depends on the presence of the N-terminal transactivation domain.

Conclusions:

  • MITF utilizes multiple, redundant interactions within its C-terminal region to bind CBP/p300.
  • These findings elucidate the molecular mechanisms underlying MITF-coactivator interactions.
  • The study provides insights into MITF function in normal melanocytes and its role in melanoma pathogenesis.

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