Pax6 and SOX2 form a co-DNA-binding partner complex that regulates initiation of lens development

Y Kamachi, M Uchikawa, A Tanouchi, R Sekido, H Kondoh

Research output: Contribution to journalArticle

277 Citations (Scopus)

Abstract

Pax6 is a key transcription factor in eye development, particularly in lens development, but its molecular action has not been clarified. We demonstrate that Pax6 initiates lens development by forming a molecular complex with SOX2 on the lens-specific enhancer elements, e.g., the delta-crystallin minimal enhancer DC5. DC5 shows a limited similarity to the binding consensus sequence of Pax6 and is bound poorly by Pax6 alone. However, Pax6 binds cooperatively with SOX2 to the DC5 sequence, resulting in formation of a high-mobility form of ternary complex in vitro, which correlates with the enhancer activation in vivo. We observed Pax6 and SOX2-interdependent factor occupancy of DC5 in a chromatin environment in vivo, providing the molecular basis of synergistic activation by Pax6 and SOX2. Subtle alterations of the Pax6-binding-site sequence of DC5 or of the inter-binding-sites distance diminished the cooperative binding and caused formation of a non-functional low-mobility form complex, suggesting DNA sequence-guided and protein interaction-induced conformation change of the Pax6 protein. When ectopically expressed in embryo ectoderm, Pax6 and SOX2 in combination activate delta-crystallin gene and elicit lens placode development, indicating that the complex of Pax6 and SOX2 formed on specific DNA sequences is the genetic switch for initiation of lens differentiation.

Original languageEnglish
Pages (from-to)1272-86
Number of pages15
JournalGenes & Development
Volume15
Issue number10
DOIs
Publication statusPublished - 15 May 2001

Keywords

  • Animals
  • Cell Differentiation
  • Cells, Cultured
  • Chick Embryo
  • Crystallins
  • DNA-Binding Proteins
  • Enhancer Elements, Genetic
  • Eye Proteins
  • Gene Expression Regulation, Developmental
  • HMGB Proteins
  • Homeodomain Proteins
  • Lens, Crystalline
  • Nuclear Proteins
  • Paired Box Transcription Factors
  • Protein Binding
  • Protein Structure, Tertiary
  • RNA, Messenger
  • Repressor Proteins
  • SOXB1 Transcription Factors
  • Transcription Factors
  • Transcriptional Activation
  • Transfection

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