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Characterization of In Vitro Differentiation of Human Primary Keratinocytes by RNA-Seq Analysis
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Characterization of In Vitro Differentiation of Human Primary Keratinocytes by RNA-Seq Analysis

Published on: May 16, 2020

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Receptor-interacting protein kinase 4 and interferon regulatory factor 6 function as a signaling axis to regulate

Mei Qi Kwa1, Jennifer Huynh1, Jiamin Aw2

  • 1From the Oral Health Cooperative Research Centre, Melbourne Dental School, and Bio21 Institute, and Department of Medicine, Royal Melbourne Hospital, The University of Melbourne, Melbourne, Victoria 3010, Australia and.

The Journal of Biological Chemistry
|September 24, 2014
PubMed

Insights

Receptor-interacting protein kinase 4 (RIPK4) directly activates interferon regulatory factor 6 (IRF6), controlling keratinocyte differentiation. RIPK4 mutations impair IRF6 activation, linking to epidermal disorders like Bartsocas-Papas syndrome.

Area of Science:

  • Cell Biology
  • Developmental Biology
  • Genetics

Background:

  • Receptor-interacting protein kinase 4 (RIPK4) and interferon regulatory factor 6 (IRF6) are crucial for keratinocyte differentiation.
  • Mutations in RIPK4 and IRF6 cause developmental epidermal disorders such as Bartsocas-Papas syndrome and popliteal pterygium syndrome.
  • The precise signaling pathways involving RIPK4 and IRF6 in keratinocyte differentiation remain unclear.

Purpose of the Study:

  • To elucidate the direct functional relationship between RIPK4 and IRF6.
  • To define the molecular mechanisms by which RIPK4 regulates IRF6 activity.
  • To investigate the impact of RIPK4 mutations on IRF6 function and their link to epidermal disorders.

Main Methods:

  • Gene promoter reporter assays
  • In vitro kinase assays
  • Coimmunoprecipitation experiments
  • Confocal microscopy
  • Gene knockdown and overexpression studies
  • Mutagenesis-based experiments

Main Results:

  • RIPK4 directly enhances IRF6 trans-activator activity and promotes its nuclear translocation.
  • The RIPK4-IRF6 signaling pathway regulates key keratinocyte differentiation factors, including Grainyhead-like 3 and OVO-like 1.
  • A Bartsocas-Papas syndrome-associated RIPK4 mutation (p.Ile121Asn) abolishes kinase activity, preventing RIPK4-mediated IRF6 activation.
  • Specific serine residues (Ser-413 and Ser-424) in IRF6 are critical for RIPK4-mediated activation.
  • RIPK4's regulation of IRF6 is influenced by the protein kinase C pathway.

Conclusions:

  • RIPK4 directly activates IRF6, establishing a critical signaling axis for keratinocyte differentiation.
  • Impaired RIPK4 kinase activity due to mutations disrupts IRF6 activation, providing a mechanistic link to Bartsocas-Papas syndrome.
  • These findings deepen our understanding of keratinocyte differentiation regulation and the molecular basis of related epidermal disorders.
Keywords:
DifferentiationGrainyhead-like 3Interferon Regulatory Factor 6KeratinocyteOVO-like 1Popliteal PterygiumProtein Kinase C (PKC)Protein PhosphorylationReceptor-interacting Protein Kinase 4Transcription Factor

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